- Acid Fast - Ziehl-Neelsen or Kinyoun stains - Cells resistant to staining and decolorization once stained

1. Recognize, isolate, and treat infected persons (Latent and active)

Exam 2 Flashcards by Abbey Barbera

How is MTB transmitted?

Person-to-person via aerosol droplet nuclei

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Who is the reservoir for MTB?

Humans only

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Prosector’s Warts are indicative of inoculation with what disease?

MTB

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MTB largely affects what age ranges?

Infants and older adults (bimodal age distribution)

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MTB manifestations in infants/IMC? (2)

Hematogenous dissemination

2. Meningitis

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MTB manifestations in older pts? (2)

Failure of immune sx

2. +/- reactivation of latent infection

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Infection risk factor for children?

Close contact w/ infected caregiver

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What are the causative agents of TB? (3)

Mycobacterium tuberculosis&raquo_space;
Mycobacterium bovis (Consumption of unpasteurized milk/ contact w/ infected animals)
Mycobacterium africanum (West African Counties, no animal reservoirs, spread by food)

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Strain of Mycobacterium used to make TB, BCG vaccine?

Mycobacterium bovis, given in highly endemic areas

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MTB characteristics (shape, cell wall, oxygen status, motility, heat sensitivity, growth) ?

Bacillus
Mycolic acid
Obligate aerobe
Non-motile
Heat sensitive, killed by pasteurization
Alveolar macrophage

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MTB staining

Acid Fast
Ziehl-Neelsen or Kinyoun stains
Cells resistant to staining and decolorization once stained

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MTB virulence factors

No classic virulence factors or toxin, structure feature create issues for the pt

Mycolic acid
Cord factor - myoside,
Lipoarabinomanna (LAM) - inhibits cell mediated immunity, scavenges ROI

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CXR findings for TB?

Fibrotic and calcified tubercle

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Risk of infection spread w/ latent TB?

No risk

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Are pts w/ latent TB treated?

Yes

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Are pts w/ reactivation or secondary TB infectious?

Yes

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Cause of Miliary Tb? (2)

Lypmhohematogenous spread of primary infection

2. Via latent focus w/ subsequent spread

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Tests for DX of Tb? (5)

XR consistent w/ TB
Skin test reactivity
Sputum stain/broth cx to detect acid fast bacteria
Rapid blood test (release of IFN-Y)
GeneXpert Rapid test for MTB and Rifampin resistance

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Goal of tx for MTB?

Recognize, isolate, and treat infected persons (Latent and active)

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MAC characteristics (shape, cell wall, oxygen status, motility, growth)?

Bacilli
Acid fast, Weakly G+
Aerobic
Ubiquitous (water, soil, plants)
Slow growing

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MAC w/ person-to-person transmission?

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Pt isolation required w/ MAC infection?

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MAC relationship w/ HIV pts?

Opportunistic pathogen. Leading cause of NTM infections in HIV+ pt

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Lady Windermere’s syndrome is associated w/ what TB pathogen?

MAC

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What gender/age range is Lady Windermere's syndrome seen in?

Elderly, non-smoking female

Type of MAC disease in IMC (AIDs) pts?

Disseminated disease (no organ spared)

Findings/tests for NTM for dx? (3)

1. Microscopy reveals acid fast bacteria and culture 2. Must ecxlude other etiologies (Fungi, TB), sterile site isolation 3. CXR w/ + pulmonary lesions 4. Final ID via molecular techniques (PCR to determine 16S rRNA sequence)

MAC tx HIV- pts?

ABX until sputum cultures are negative for 1 yr

MAC tx in HIV + pt w/o infection?

Chemoprophylaxis w/ CD4 < 50 cell/uL, discontinue 3 months after CD4 > 100 cell/uL

MAC tx in HIV+ pt w/ MAC infection

- Lifelong (if w/o immune reconstitution) | - Begin tx for 2 weeks then anti-HIV HAART

Mycobacterium abscessus is especially difficult to treat in what disease population?

MTB pathogenesis?

Granulomas (2-6 weeks post infection) → caseous lesions (fibrotic tubercle) → calcifies & seen on x-ray → disease stops

MTB infection outcomes? (5)

- Immediate resolution (no active TB) - innate immune system (alveolar macrophage) able to clear bacteria - Primary disease - Progressive primary (active) disease - Latent infection (inactive bacteria, - signs/sx, not infectious, treatment necessary) - Endogenous reactivation/secondary TB (+ signs/sx, infectious, insidious, lesions: caseous lesions → TB bacilli to bronchi → hematogenous spread

What is HAART?

Highly acute anti-retroviral therapy

Coryza, cough and conjunctivitis is concerning for what disease?

Measles

Koplick's spots are diagnostic for what disease?

Measles

Mealse rash starts and spreads where?

Head, spread to body

When is a measles pt the sickest?

During rash/ highest fever (3-4 days after prodrome)

Acute symptomatic encephalitis is a complication associated with what disease?

Measles | also some associated w SSPE = subacute sclerosing panencephalitis

What complication is responsible for most deaths in measles pts?

Pneumonia

Is there a healthy carrier state associated with measles?

No, none known

Transmission of measles is via?

Respiratory droplets (highly contagious)

Is measles a disease of adulthood or childhood?

Primarily a disease of childhood (might be changing)

FA test for pt w/ measles will show?

Multinucleated giant cells

Largest preventative measure for measles?

MMR vaccine | also immune globulin BayGam for exposed non-immune subjects

MMR II is what type of vaccine?

Live, attenuated vaccine

Who should never receive MMR vaccine?

Pregnant, IMC

What % of population must be vaccinated to halt measles persistence?

95%

Rubella is also referred to as? (2)

1. German Measles | 2. "little red"

What age group often escaped rubella infection?

Children

Congenital rubella syndrome (CRS) is a complication due to what?

Maternal rubella infection during first trimester (worst prognosis earlier then infection, 1st month > 4th month)

Cataracts, hearing loss, and cardiac defects are sx of what?

Congenital rubella syndrome (CRS)

2 unique properties of HSV?

1. Capacity to invade and replicate in CNS | 2. Ability to establish latent infection

Shallow vesicles on erythematous +/- crusting and ballooning is concerning for?

HSV

Can the primary HSV infection be asymptomatic?

Yes

How does HSV become a latent virus?

Retrograde transport of virus through sensory neurons --> infection of dorsal root ganglia

What is the timeframe for completely clearing an HSV infection from the body?

None. HSV is for life!

Stress, menses, sunlights and nutrition are all triggers for what viral infection?

HSV

If a pt has a larger and more extensive initial outbreak with HSV, will their probability of recrudescence be higher or lower?

Higher

Will recrudescence of HSV occur in the presents of active humoral and cellular immunity?

Yes

Who is the reservoir for HSV?

Humans only

Can you transmitted HSV infection even if asymptomatic?

Yes

Are HSV-1 infection common in early life or later life?

Early life via casual contact

How are HSV-2 infections transmitted?

Sexual contact

Presence of enlarged or fused cells on Tzanck smear is concerning for what disease?

HSV

ACV (Acyclovir) is effective in treating HSV because viral enzyme thymidine kinase phosphorylates the drug for activation and then what?

Halts viral DNA replications b/c it lacks 3'-OH group | Will only get into infected cells when active

Varicella-zoster virus is responsible for what 2 disease states?

1. Chickenpox | 2. Shingles

Asymmetrical vesicular pruritic rash is concerning for what disease?

Chickenpox

Viral infection through conjunctiva or respiratory tract mucosa is concerning for what disease?

Chickenpox

Who is the only reservoir for chickenpox?

Humans

VZV infections peak during what seasons?

Winter-SPring

What age group has the highest incidence of VZV?

5-9 y/o

When is VZV pt most contagious?

1-2 before appearance of lesions and 4-5 days after

Are prodromal VZV present in older children and adults or younger children?

Younger children

VZV rash is primarily located where?

On the trunk

Is aspirin recommended in tx of chickenpox?

No, concerning for Reyes syndrome

TX for Chicken pox?

Sx relief - self limited Acyclovir Immune serum VariZig (high risk)

Varivax is the vaccine for what disease?

VZV

IS the VZV vaccine safe in pregnancy?

Will shingles cross midline?

No, unilateral dermatomal distribution

Shingles is recrudescence of what viral infection?

VZV

Searing, burning, stabbing lesions that don't cross midline are concerning for?

Shingles

Most common complication fo shingles?

Postherpetic neuralgia

Can a pt present with shingles but never have had or been vaccinated against chicken pox?

Zostavax and Shingrix are vaccines against what?

Shingles

Is Zostavax or Shingrix a live vaccine?

Zostavax

Is Zostavax or Shingrix given in 2 doses?

Shingrix

Exanthem subitum, roseola infantum/6th disease are caused by what?

Human Herpes Virus-6 (HHV-6)

HHV-6 is dx by what? (2)

1. Detection of AB by EIA | 2. PCR

High fever w.o any obvious sources is concerning for what?

HHV-6

TX of HHV-6 does not require? (3)

1. Isolation 2. Anti-viral therapy 3. Primary preventative measures

Fifth's disease/ Erythema infectiosum is causes by?

Parvovirus B19

Prodrome of this disease is follow by maculopapular rash in "slapped cheeked" appearance?

Parvovirus B19

Arthralgia or arthritis follow maculopapular rash may be concerning for?

Parvovirus B19

Parvovirus B19 is most common in what seasons?

Later winter and spring

Virus that produces warts?

HPV

HPV 6 & II produce anogenital warts or cervical dysplasia and cancer?

Anogenital warts

HPV 16 & 18 produce anogenital warts or cervical dysplasia and cancer?

Cervical dysplasia and cancer?

Age range for Gardasil 9?

M/F 9-45

Dermatophytes require what for growth?

ketatin (hair, skin, nails)

Do dermatophytes infect mucosal surfaces?

What enzymes allows dermatophytes to inhabit keratinized regions of the body>

Keratinase

Dermatophyte test medium (DTM) allows for early detection of infection or can only be used to different source of dermatophyte?

Early detection

Arthroconidium is what?

The infective stage of disease for dermatophytes

Trichophytin is what? (2)

1. Galactomannan peptide | 2. Crude antigen of dermatophytes (CHO component = immediate response, Peptide component = delayed response)

How does 10% potassium hydroxide allow for visualization of fungi?

Digests human tissues, leaving fungal components intact

Dermatophytes utilize nitrogen compounds preferentially over carbs. DTM will turn what color?

Red (alkaline)

Dermatophyte test medium (DTM) is selective and differential for what?

Selective: Cyclohexamide and ABX Differential: fermentation of sugars

Animal pathogens that may be transmitted to people are what?

Zoophilic

Antropholilic Dermatophytes are spread via what transmission?

Human to human

Soil to people transmission is what?

Geophilic

Geophilic dermatophytes will invade non-viable or viable keratinized tissue?

Non-viable

Fungi prefer dry or moist areas of the body?

Moist

Globally where are fungal infections more prevalent?

Tropics

Microconidia, macroconidia and sexual spores are infectious or non-infectious?

Infectious

Fragmented hypheal elements in hair, nails, outer skin are what?

Arthrospores

Lesions with inflamed edges and a central clearings are concerning for what infectious pathogen?

Fungi

Transmission pattern for arthrospores?

Person to persons

Are arthrospores infectious?

Yes

Microconidia is uni or multi cellular?

Uni

Macroconidia is uni or multicellular?

Multi

Classification for an allergic dermal reaction to fungal antigen occurring in areas devoid of organisms

Dermatophytid

Most common dermatophytid?

Athlete's foot

How are dermatophytid reactions spread?

Itching

Will dermatophytid be present at only 1˚ or 1˚ and 2˚ sites?

Only primary

"Id reaction" is associated with what fungal infection?

Dermatophytid

What is an "id reaction" treated as?

An allergy

What is the most common trichophyton species?

T. mentagrophytes

Are trichophyton often fluorescent or not fluorescent?

Not fluorescent

What do all trichophyton species make?

Pencil-shaped macroconidia w/ thin walls

What 3 things do trichophyton produce?

Hyphae (spindle shaped), microconidia, macroconidia

What is the most common causative agent of tinea captitis?

M. canis

What disease is described as mostly a childhood disease that involves the hair and scalp?

Tinea capitis

What are the 2 types of ringworm infections?

Endothrix (infects throughout follicle) | Ectothrix

What infection is associated with certain species producing a black dot ringworm, intense inflammation, scarring/ permanent alopecia, and can be zoonotic?

Tinea capitis

With tinea capitis, infected hair can break off and lead to what?

Alopecia

If a patient presents with itching, peeling, and crackling of the skin in the toe webs/ soles of feet, what should you be concerned about?

Tinea pedis (most prevalent of dermatophytoses)

What are predisposing factors for tinea corporis and tinea cruris?

Diabetes, obesity, excessive perspiration

How are tinea corporis and tinea cruris transmitted?

Direct and indirect contact objects (towels, clothing, bed linens)

What is tinea unguium?

Onychomycosis (ringworm of the nail)

What infection is associated w/ the following: - Finger/ toenails become discolored/ thick - May be mistaken for psoriasis - Usually has fungal involvement (Candida)

Tinea unguium

What are the most commonly encountered opportunistic mycoses?

Candidiases

What infection is associated with colonization of normal flora of the skin and mucous membranes?

Candidiases

What infection is associated with the following: - Absence of competing normal flora - Introduction to abnormal site - "Pathologic" change in microenvironment - Inborn or acquired immune defect - Use of broad-spectrum abx

Candidiases

Although candida albicans does not have many virulence factors, all species are capable of attachment, and what is the most adhesive?

Germ tube more adhesive than yeast cell

How is a Candida infection diagnosed?

Direct microscopic exam - Large G- cells - Yeast cells - Pseudohyphae - True hyphae

Besides direct microscopic exam, how is a Candida infection diagnosed?

Cultures (germ tubes) Histology Serology

What is tinea versicolor aka?

Malassezia furfur

What fungi is described as microscopically having short, unbranched hyphae and somewhat spherical cells and also has yeast like colonies?

Malassezia furfur

If you see a "spaghetti and meatballs" arrangement on a microscopic exam, what fungal infection should you be suspicious of?

Malassezia furfur

What type of GF is required for growth of Malassezia furfur?

Lipophilic (fat, sebaceous glands)

In what populations is Malassezia furfur most commonly found?

Tropics, young adults

What fungal infection is associated with macular patches of depigmented or hyper pigmented skin that may enlarge and can lead to dandruff?

Malassezia furfur

How can Malassezia furfur be identified?

Microscopic exam in skin scrapings, KOH prep

What fungal infection is tinea nigra aka?

Hortaea werneckii

What fungal species is dimorphic and can grow in saturated salt solutions?

Hortaea werneckii

What fungal species is identified as a tropical disease, results in brownish lesions (melanin), and is identified with KOH and microscopy?

Hortaea werneckii

When is a bacterial skin infection considered complicated?

``` Pre-existing wound care Deeper tissues Requires surgery Unresponsive to therapy/ recurrent Associated w/ underlying disease ```

Recurrent infections raise concern over colonization with what?

Resistant bacteria or underlying issues

Although normally inoculum of bacteria (staph) introduced through breaks in skin is not large, what happens if a foreign body (splinter, stitches) is present?

Infectious dose drops dramatically

What disease is associated with the sebaceous follicles and is a noninfectious form of folliculitis?

Acne vulgaris

What is often the initial trigger for acne vulgaris?

Androgen hormones

What bacteria responsible for acne vulgaris is G+, anaerobic rod, and on normal skin flora (sebaceous glands)

Propionibacterium acnes

What does inflammatory acne develop?

When follicular contents rupture into dermis | papule > pustule > nodule

What is the usual cause of Folliculitis?

Staph. aureus

If a pt presents w/ mild pain, itching/ irritation with pustules or nodules surround hair follicles?

Folliculitis

If folliculitis is not responding to tx, what should be performed to r/o other possible causes?

Gram stain | r/o G- etiology or MRSA

What are the 2 primary pathogens responsible for superficial folliculitis?

Staph. aureus and Pseudomonas aeruginosa

Which pathogen is responsible for the majority of abscess-type infections, is G+, and coagulase-+ cocci in clusters? (superficial folliculitis)

Staph. aureus

``` Which pathogen is described by the following: - G- rod - Opportunistic pathogen - Ubiquitous - Pyocyanin/ pyoverdin (superficial folliculitis) ```

Pseudomonas aeruginosa

P. aeruginosa is often the cause of what type of folliculitis?

"Hot tub" folliculitis

If a pt presents 8-48 hrs post exposure to contaminated water and is complaining of an itchy maculopapular rash with some pustules, what is the likely responsible pathogen?

Pseudomonas aeruginosa

A furuncle (boil) is an abscess caused involving a hair follicle and surrounding tissue caused by what pathogen?

S. aureus

What are clusters of furuncles with subcutaneous connections that extend into the dermis and subcutaneous tissue?

Carbuncles

What other sxs might accompany carbuncles?

Fever and prostrations

What populations are more commonly affected by furuncles and carbuncles?

Obese, immunocompromised, diabetic, elderly

If furuncles or carbuncles are > 5mm, do not resolve w/ drainage, are spreading, or occur in IMC/ subjects at risk of endocarditis, how are they treated?

Abx (effective against MRSA) | More aggressive combo therapy with rifampin if + fever/ multiple

What condition is a superficial skin infection with crusting or bullae and what is the most common pathogen cause?

Impetigo | Cause= steph, strep (or both)

What is the deeper, ulcerative form of impetigo?

Ecthyma

Moist environment, poor hygiene or chronic nasopharyngeal carriage of agents are RF's for what disease?

Impetigo/ ecthyma

If a pt presents with clusters of vesicles that rupture and crust over around the nose and mouth, what should you be concerned for?

Non-bullous impetigo

What is the #1 cause of non-bullous impetigo?

S. aureus (with MRSA in 20%) | Strep. pyogenes co-infects frequently

In bullous impetigo, exfoliative toxin that disrupts epidermal cell connections results in vesicles enlarging to form what?

Bacteria-colonized fluid-filled bullae

What is the most common pathogen involved with bullous impetigo and what role does the toxin play?

S. aureus (specific strains) | Toxin does not disseminate beyond local sites of infection

A severe form of impetigo featuring deep invasion of the dermis caused by the same agent producing non-bullous impetigo is known as what?

Ecthyma

Lesions with hard crust that is deeper and thicker than impetigo underlying ulcerated tissue is known as what?

Ecthyma

Staphylococcal scalded skin syndrome is aka?

Ritter's disease

Acute and extensive epidermolysis due to action of staph toxin (exfoliation) that splits the skin just beneath the granule cell layer is what?

Staphylococcal scalded skin syndrome

Why are the bullae in Staphylococcal scalded skin syndrome sterile (no bacteria or leukocytes)?

Due to toxin

Positive Nikolsky's sign, skin peels easily, and desquamated areas look scalded fits the description for what condition?

Staphylococcal scalded skin syndrome

Is the mortality rate for scaled skin syndrome high or low?

Low

Erythema and edema to R LE (unitlateral) the appears deep w/in the dermis and has less distinct borders is concerning for erysipelas or cellulitis?

Cellulitis

Superficial cellulitis (erythema with raised lesions) w/ focal dermal involvement and distinct borders is concerning for what?

Erysipelas (st. Anthony's Fire)

Most common pathogen for erysipelas?

Group A, B-hemolytic Streptococci, Strep pyogenes

How do erysipelas spread once dermis is infected?

Superficial lymphatic vessels

Will you always be able to pinpoint the source of cellulitis infection?

No, wound may not be evident

HEET (heat, erythema, edema, tenderness) is the hallmark for what bacterial skin infection?

Cellulitis

When treating cellulitis should you assume the infection is caused by a single pathogen?

No, may be mixed etiology

Why should NSAIDs be avoided in the treatment of cellulitis?

Can mask pain of developing myonecrosis (something more serious than cellulitis)

What is a warning sign that cellulitis infection might be necrotizing fascitis?

Out of proportion pain

Cellulitis pathogen associated w/ cat bite?

Pasteurella multocida

Redness, swelling warmth, pain + what signs/sx would make you concerned for a MRSA infection? (4)

1. Fluctuance (evidence of fluid) 2. Yellow/white center 3. Central point (head) 4. Draining pus or ability to aspirate pus w/ syringe

What gene can you screen for that might tell if you are Methicillin resistant?

MecA

Infections of the epidermis? (3)

1. Erysipelas 2. Impetigo 3. Follicutlits

Infections of the dermis? (3)

1. Ecthyma 2. Furunculosis 3. Cabunculosis

Infection of the superficial fascia? (1)

Cellulitis

Infection of the subQ tissue and fascia? (1)

Necrotizing fasciitis

Infection of the muscles? (1)

Myonecrosis (clostridial and nonclostridial)

Why is it difficult to dx NF w/o surgical intervention?

Initially overlying tissues appear unaffected

Why is muscle tissue spared from NF infection?

Generous blood supply

Type 1 NF pathogens are most common. What disease state disease state puts you at increased risk?

If you have a hx of surgery, previous abscess or GI perforation are you at risk for Type 1 or Type 2 NF infection?

Type 1

Flesh eating bacteria or streptococcal gangrene more common in abdominal/groin area or the extremities?

Extremities

Pain out of proportion and skin color changes w/ bullae within 3-5 day of onset is concerning for?

Necrotizing fasciitis

What differentiates NF from cellulitis?

Failure to respond to ABX (cellulitis will respond w/in 24-48hrs to abx)

What is the tx for NF?

Surgical debridement/apmutation w/ IV ABX

Presence of no true pus, but brownish exudate and pain out of proportion/ rapid progression is concerning for?

Gas gangrene is most caused by what pathogen?

Clostridium perfringens type A (90%) | - spore forming, G+, anaerobic bacillus

Gas gangrene primarily affects what tissue?

Muscle

Gas gangrene is also known as?

Clostridial myonecrosis

Skin that is tense/edematous, intensely tender, and crepitant (due to H2 gas) with bronze appearance is concerning for?

Gas gangrene

Rapid onset of pain ≤24 hrs following anaerobic cell/spore infection is concerning for?

Gas gangrene

Gram stain of tissue biopsy for gas gangrene will show what?

Muscle necrosis , gram variable rods, and tissue destruction

Hyperbaric oxygen therapy, surgery, and IV abx are tx for what dermal infection?

Clostridial myonecrosis

Causative agents for toxic shock syndrome? (2)

Staph aureus and strep pyogenes

Fever and sunburn like rash to entire body is concerning for what?

TSS

Early presentation for Strep TSS?

Soft tissue inflammation at site of skin infection

True or False: Pt's w/ strep TSS are usually bacteremic and have NF?

True

Enterotoxin type B superantigen is associated with strep or staph TSS?

Staph

True or false: Pt's with staph TSS are otherwise healthy w/ no pre-existing skin infections?

True

Which pathogen of TSS is associated with tampon use?

Staph

What pathogen is a burrowing mite that is the most serious of the mites, a close relative of ticks, and leads to scabies, crusted scabies, mange, and seven year itch?

Sarcoptes scabiei

What is the morphology of Sarcoptes scabiei?

Small mite w short legs

Is a male or female Sarcoptes scabiei fertilized on the skin surface, burrows into the epidermis, and completes its life cycle in 5 weeks then dies in the burrow?

Female

Does a male or female Sarcoptes scabiei have a shorter life span and remains on the skin surface or produces a shallow burrow?

Male

Where are the eggs of Sarcoptes scabiei laid and how soon after incubation do larva emerge?

Under the skin | Larva emerge after 4 days

How long after Sarcoptes scabiei hatch do adult mites develop?

2 weeks

How long after someone is infested with Sarcoptes scabiei does it take for sxs (itching) to develop?

First infestation = weeks | Re-infection = 24 hours

What causes the majority of clinical issues (intensely pruritic eruption that is worse at night) with Sarcoptes scabiei?

Burrowing

What pathogen has an incubation period of 1 month and results in crusted scaling lesions that are intensely pruritic, with lesions having hundreds to thousands of mites?

Sarcoptes scabiei- crusted (Norwegian) scabies

What population is readily infected w/ crusted scabies?

HIV

What condition is similar to Norwegian scabies, but the lesions may be blood filled?

Pediatric scabies

How is scabies most commonly spread?

Direct person contact (STI) | Crowded living conditions

How are scabies identified?

Apply mineral oil, scrape lesion and visualize microscopically (look for whole mite or mite parts, eggs, or fecal pellets in burrows)

What is the pathogen responsible for pubic lice/ "crabs"?

Phthirus pubis

How does Phthirus pubis infected the pubic area?

Nits (eggs) cemented to hair, adults bite and feed in pubic area

How is Phthirus pubis transmitted and identified?

Transmitted by sexual contact or contaminated bedding | ID by visualizing louse or nit

What is the pathogen responsible for pediculosis?

Pediculus humans

What pathogen is a vector for epidemic typhus?

Pediculus humans

What pathogen is a nit cemented to a fiber in clothing or human hair and has an egg-to-egg cycle that takes about 3 weeks?

Pediculus humans

If a pt presents with bite irritation (parasite is bloodsucking), "vagabonds disease" (years of infestation) and darkened, thickened skin, what should you be concerned about?

Pediculus humans/ pediculosis

How is P. humanus spread?

Easily- crowded conditions, conditions where clothing cannot be changed often

What pathogen is 1-4mm in length, laterally compressed, and has short spikes on its legs that allow attachment to the host?

Pulex irritans (human flea)

What does Pulex irritans need to survive?

Blood (it is a parasite)

What do Pulex irritans inject during a blood meal?

Saliva that initiates an allergic response

What is the main manifestation of an infection w Pulex irritans?

Rash

What is a tick-borne disease via a brown dog tick (AZ)?

Rocky Mountain Spotted Fever

What pathogen is responsible for Rocky Mountain Spotted Fever?

Rickettsia rickettsii

What pathogen is described as G-, obligate intracellular, non-motile, and pleomorphic and can cause a potentially fatal disease if not tx in the first few days of sxs?

Rickettsia rickettsii

During what time of year is Rocky Mountain Spotted Fever seen more frequently?

Summer months (peak in June and July)

If a pt presents w hx of a painless bite and didn't notice sxs until 2-14 days post bite, what disease should you be concerned about?

Rocky Mountain Spotted Fever

What parts of the body does Rickettsia rickettsii invade?

Endothelial cells that line blood vessels

What early sxs and sudden onset sxs are seen with Rocky Mountain Spotted Fever?

Early sxs are non-specific | Sudden onset sxs = fever, HA

What 2 types of rash are seen with Rocky Mountain Spotted Fever?

1. small, flat, pink non-itchy spots (macules) | 2. red to purple spotted petechial rash +/- pinpoint hemorrhages

Which type of Rocky Mountain Spotted Fever rash will likely be seen on wrists, forearms, ankles and spreads to trunk, palms and soles 2-5 days post infection?

small, flat, pink non-itchy spots (macules)

Which type of Rocky Mountain Spotted Fever rash will likely be seen after 6 days post infection, and is a sign of late infection/ severe disease?

red to purple spotted petechial rash

If you suspect a pt is infected with Rocky Mountain Spotted Fever, do you wait to treat until receiving laboratory confirmation?

No- most successful if tx initiated w/i first 5 days

Why is Rocky Mountain Spotted Fever a difficult disease to deal with?

Similarity to other diseases | Difficult to detect until disease is in late stages

Why are diagnostic tests not a good option for Rocky Mountain Spotted Fever?

Detectable antibody titers are not visible for 7-10 days post infection

What is the gold standard for dx of Rocky Mountain Spotted Fever?

Indirect immunofluorescence w/ a R. rickettsii antigen (2 samples 2-4 weeks apart)

What pathogen is responsible for African sleeping sickness?

Trypanosoma brucei

What pathogen is responsible for Chagas disease?

Trypanosoma cruzi

What pathogen is responsible for Leishmaniasis?

Leishmania spp.

What disease is prevalent in Mexico, Central America, and South America, is considered a neglected parasitic infection (NPI) by the CDC in the US and is associated w survivors that typically exhibit altered organ function?

Chagas disease

What is the vector for Chagas disease?

Triatomine bugs ("kissing bugs")

What parasitic protozoan is transmitted through feces of the triatomine bug, blood transfusions, organ transplants, and congenital?

Trypanosoma cruzi

What happens once the trypomastigote (T. cruzi) enters near the inoculation site?

It differentiates into amastigotes

What happens to the amastigotes (T. cruzi) once differentiated into?

Replicate by binary fission in cells, differentiate, and release into circulation to rupture host cells

What are the key characteristics of the acute stage of Chagas disease?

Asx to mild manifestation Non-specific signs/ sxs, +/- Chagoma Romanas sign- swelling of eyelid near entry site

What are the key characteristics of the chronic stage of Chagas disease?

Pseudocysts of amastigotes in cells (muscles and nerves affected, degeneration and necrosis) Chronic inflammation Cardiac > intestinal complications

How long can the infection with Chagas disease be asx?

Years, or even for life

How is Chagas disease diagnosed?

Parasite under microscopy- blood smear (acute) or biopsy (chronic) Serological tests

What is involved with prevention and control of Chagas disease?

``` Insecticides/ housing improvements Bednets Screening of blood donors Testing of organ, tissue, cell donors Screening of newborns/ children of infected mothers for early dx/ tx ```

Viral infection that causes infectious mononucleosis (IM)?

EBV

EBV is linked to what form of cancer?

Burkitt's lymphoma

IM is a B or T cell infection?

B cell. Induces polyclonal expansion of lymphocytes

Sore throat, symmetrical lymphadenopathy, and fever +/- hepatomegaly is concerning for what?

Downey cells (atypical lymphcytes) appear in the circulation for pt's infected with what disease?

In IM does B cells or T cells generate most of the pt's sx?

T cells

Transmission pattern for EBV?

Person to person

Peak incidence of EBV causing IM?

17-25 yrs

Early infection w/ EBV in a pt from regions of Africa is concerning for what?

Burkitt's Lymphoma

Presence of what type of antibodies are help dx EBV IM?

Heterophile AB

Why might the monospot test give a false negative?

Age-specific reactivity. Less useful in kids so use IgM anti virus capsid antigen serology

When treating IM pt with penicillin you must warn them about?

Penicillin reaction rash

Which virus, CMV or EBV, DOES NOT produce heterophile antibodies?

CMV

What populations are most at risk for CMV?

IMC, transplant pts, infections occurring during pregnancy

Does MMR provided lifelong immunity to mumps for all recipients?

Not for egg or neomycin sensitive pts. Pts that have been vaccinated are still getting the disease.

How is mumps controlled?

Vaccination

Borrelia burgdorferi is the pathogen for what disease?

Lyme disease

Pt presents with erythema migrans/red bulls eye rash. What stage of lyme disease are you suspecting?

Stage 1: Acute localized disease

Flu sx, brief asymmetric arthritis attaches and/or secondary annular skin lesions may be concerning for what stage of lyme disease?

State 2: Subacute disseminated disease

Chronic lyme disease is easier or harder to treat?

Hard the further the disease process

Chronic lyme disease (stage 3) is associated with primarily what sx?

Musculoskeletal. | Arthritis attacks become more persistent and last long

What general location of the US has the highest reported cases of lyme disease?

Vector for lyme disease?

Tick vector (deer or black-legged)

Ticks exhibit what type of behavior?

Questing behavior

Lyme disease reservoir hosts?

Small mammals and birds

What form of the black legged tick causes large portion of infections in humans?

Nymphal

Serology test for lyme disease?

EIA w/ western blot follow up if positive (positive by 4th week of infection)

What disease states might cause false positive on lyme disease serology test?

Syphilis, mono, SLE, RA, oral infection w/ spirochetes

How can you prevent lyme disease?

Control and avoidance of vector contact (Deet, tick checks following outdoor activity)

Post TX Lyme Disease Syndrome is chronic or will improve with time?

Most should improve with time

Source of Hep A and Hep E?

Feces

Route of transmission for Hep A and E?

Fecal-oral

Are Hep A and E a chronic infections?

No | A= infectious

Source of Hep B, C, and D?

Blood/blood-derived body fluids B= serum C= transfusion-associated

Route of transmission for Hep B, C, and D?

Percutaneous, permucosal

Is Hep B a chronic or acute infections?

Chronic

True or false: Hep C and D are chronic infections?

true

Hep A will have IgM antibody on ELISA, True or False?

True

HAV prevention measures? (5)

1. Hand washing 2. Avoidance of contaminated food/water 3. Post exposure prophylaxis 4. Vaccine 5. Education

Which Hepatitis virus is infectious cause of primary hepatocellular carcinoma?

Chronic HBV

Presence of double walled Dane particle is indicative of infectious or non-infectious form of Hep B?

Infectious

Largest reservoir for HBV?

Chronic hepatitis pts

Are HBeAg positive pts at risk of transmitting HBV infection?

Yes

What are newborns vaccinated against HBV?

90% of infections become chronic

IgG and anti-HBc indicated past or present HBV infection?

Past

Rapid Hepatitis virus test detect what type of HBV antigen?

Surface

Is HBV a self limited disease for most adults?

Yes, no specific curative tx exisits

Do tx for chronic HBV result in a cure?

No only inhibit viral replications, prevent liver damage progression

True or false, Subunit vaccine is available for HBV?

True

True or false: immunoglobulin is available for HBV prophylaxis?

True

Which form of hepatitis requires presence of chronic HBV and superinfection?

HDV

HDV will increase or decrease the severity of HBV?

Increase

Pts with chronic HBV are a reservoir for what disease?

HDV

Positive delta antigen on ELISA is indicative of what hepatitis infection?

HDV (but must also have active HBV)

True or false: HBV vaccine will protect against HBV and HDV?

True

Form of hepatitis associated with needle sticks and M/M unprotected sex?

Hep B

Form of hepatitis that most often occurs post transfusion?

Hep C

Establishment of chronic infection is the hallmark for what form of hepatitis?

HCV

True or false HCV often does not progress to cirrhosis and liver failure

False. It often does!

Serologic tests will show increased or decreased anti-HCV over time?

Increased

Acute HCV will most often develop into what disease?

Chronic

Factors that promotes HCV infection progression? (5)

1. Alcohol use 2. Infection at age ? 40 3. Male sex 4. Hep B co-infection 5. HIV co-infection

What is dx of HCV difficult?

chronic state and acute phase viremic patients often escape detection

TX for HCV ?

Direct acting antiviral agents (DAAs) , possibly curable

Are combination regiments the same for all 6 HCV genotypes?

No, vary with virus genotype

If HBV and HVC co infection which form usually dominates and is thus treated first?

HCV

DAA tx that eliminates HCV will: 1. Eliminate HBV? 2. Activate HBV?

Activate

True or false: because HCV tends to suppress HBV activity, we are not sure how often the two viruses are found together?

True

HCV prevention? (2)

1. Blood screening | 2. Effect to ID compensated, unrecognized infections

What are the two leading causes for liver transplant?

Cirrhosis and hepatocellular carcinoma

Will life transplant be curative for HBV and HCV confection?

Yes

Is a liver transplant pt at risk for recurrent infection?

Yes, if no edu/lifestyle change AND b/c IMC

Pt presents w non-specific sore throat and swollen lymph glands mimicking a mono-like condition... what are you concerned for?

Initial HIV infection

When is HIV in a period of high transmission risk?

Early stages when pt unaware they are HIV- infected (high levels of virus in circulation)

All pts with HIV are considered what?

Life-long carriers and continually infectious

When is AIDS (stage 3 HIV) diagnosed? | What are CD4 T cell levels at?

When severe damage to immune system is evident | CD4 T cells < 200 uL

AIDS defining conditions emerge as what declines?

Immune system function

What disease is associated w/ Kaposi's sarcoma, pneumocystis pneumonia, MAC infection, severe CMV disease, cryptosporidiosis, and candidiasis?

AIDS

What defines the "fast" HIV disease course class?

3 years or less to AIDS

What defines the "intermediate" HIV disease course class?

AIDS emergence ~ 1 decade post infection

What defines the "long term non-progressors" HIV disease course class?

> 10 yrs (under 5% of cases)

What pathogenic agents has the following characteristics: - Human retrovirus - RNA genome - Enveloped - Reverse transcriptase

HIV/ AIDS

AIDS is now considered to be a probable what that has entered human populations?

Zoonosis (animal disease)- contact via primates/ bushmeat

What has sequencing of the HIV/ AIDS viral genome revealed?

A focus in African and entry of HIV into human populations several times

How is HIV/ AIDS most commonly spread?

STIs

What are 3 myths about HIV?

Polio vaccine = source of HIV-1 Pt zero Deliberate spread

How can HIV-1 become a latent disease?

Entry into T/B memory cells (reverse transcription)

How does HIV exhibit cytopathic effects?

TH cell loss = immunosuppression Formation of "swarms" *mechanism of viral killing uncertain*

Is you notice Gohn lesions and ipsilateral calcified hilar lymph nodes on CXR, what is this concerning for?

Ranke complex, concerning for healed primary TB

What are the 3 most common HIV routes of transmission?

1. sexual contact 2. parenteral (IV drug use, needle sticks) 3. perinatal

Is HIV-1 or HIV-2 more common worldwide? | Is HIV-1 or HIV-2 less easily transmitted?

HIV-1 = worldwide, HIV-2 = W Africa | HIV-2 less easily transmitted, exhibits slower progression to AIDS, resistant to NNRTIs

What is the progression pattern of HIV?

1. Infection 2. Free replication 3. Pt ab response 4. Latent virus changes and no longer immune

What is the goal of HIV tx?

Keep virus @ low levels and keep from killing CD4 lymphocytes

What 2 steps are used for dx of HIV? (HIV ab)

1. EIA screen (general) | 2. Western blot

What designates an HIV + test on Western blot for CDC?

2 cross-reacting bands

What is the role of direct tests for HIV?

Determine how much virus is present | Protect blood supply (donated blood screened)

Which direct test is able to detect and quantify the HIV virus?

Nucleic acid test (NAT)

Why should you do direct tests and not just AB tests for HIV?

Early disease may not have ab yet

What is the general tx for HIV but what is important to know about it?

Tx = combo of antiviral agents, but NOT curative

What 3 types of antiviral agents are included in combo treatment for HIV?

Reverse transcriptase inhibitors Protease inhibitors Fusion-penetration inhibitors

What is the role of viral load tests for HIV pts?

Tests amount of HIV in blood Watch trend of counts Run frequently if early in disease

Why does HIV impact cognitive function?

Neuron damage

What is the best control method for HIV?

Prevention/ education

Anti-retroviral therapies drive virus levels to undetectable levels... why is this important?

Undetectable = un-transmissible

What are new strategies for ending HIV transmission?

PrEP if at risk | Early ID/ therapeutic tx

How is malaria transmitted?

Plasmodia from salivary glands of Anopheles female mosquito

What are the Malaria important species, and which are the 2 most common?

``` Plasmodium vivax (most common) P. falciparum (most common) P. malariae P. ovale P. knowlesi ```

What are the 2 phases of malaria life cycle, contributing to its ability to evade host defenses?

Human phase and mosquito phase

How is the malaria life cycle initiated in humans?

Injected of Plasmodium sporozites (motile forms) in saliva

How do sporozoites divide once they migrate to the liver?

Asexual division = schizogony

What is the name of the life cycle form released from the schizogony phase of the malaria life cycle?

Merozoites

What stage of the malaria life cycle is the vaccine target?

Sprorozoites

What do merozoites infect?

Other liver cells or RBCs (erythrocytic cycle)

Once in the RBC, merozoites enlarges and undergoes a differentiation into what?

Ring trophozoite (uninucleate)

As trophozoites age, what can they develop into?

Amoeboid trophozoites

In the malaria life cycle, a single nucleus can also divide to produce what?

Schizont

Erythrocytic schizonts are multinucleated cells that produce what?

Erythrocytic merozoites

After an infected RBC ruptures and merozoites escape to invade new cells, what happens?

Schizogony begins again or gametogony (sexual cycle) is initiated

What leads to sexual reproduction within the mosquito? | malaria life cycle

Erythrocytic merozoites develop into gametocytes, which are then taken up by mosquito

Sporozoites produced in the mosquito and traveling to the salivary glands of the mosquito contribute to treatment difficulty?

Exchange of DNA allowing the mosquito to change and gain drug resistance

What does the malaria organism consume?

Hemoglobin

Release of pyrogenic waste from rupture of RBCs travel to hypothalamus and cause what?

Increased thermal set point = fever and chills (sxs)

If a pt presents with episodes of 1-2 hours of severe shivering and high fever following it, what is the cause? (Malaria)

TNF release (inflammation) after pyrogen travels to hypothalamus

What is one of the first signs of malaria?

Anemia due to RBC destruction

Why is malaria difficult to treat?

Mimics other diseases

What 2 things can provide a pt with malaria resistance? What forms are they specifically resistant to?

Sickle cell anemia (all forms) | Lack of Duffy antigen (P. vivax)

What is the malaria vaccine and what is the issue with it?

RTS, S (Mosquirix) | Low efficacy

What are the reservoirs for malaria?

Humans and simians

What role will climate change play in the spread of malaria?

Increasing land mass and population being exposed to disease | Organism can survive in areas it didn't used to be able to

Plasmodium vivax is aka what?

Vivax malaria, benign tertian malaria

Why is Plasmodium vivax is seldom fatal?

Infects young erythrocytes (receptor no longer available once erythrocyte ages)

Pt prevents with relapse of malaria infection 3-5 years after initial disease. What organism are you concerned about and what is the reason for the relapse?

Plasmodium vivax | Activation of liver hypnozoites

If Plasmodium vivax is microscopically evaluated, what should you see?

Enlarged infected RBCs with Schuffner's dots

How is infection with Plasmodium vivax controlled?

Protection from mosquitos (nettings, insecticides, repellants)

What malaria organism has the capability to infect any age RBC?

Plasmodium falciparum (malignant tertian malaria)

Rapid multiplication and high parasite numbers lead to what sxs?

High fever/ Blackwater fever

Pt presents w/ high levels of free Hgb in urine. What are you concerned about and what might this lead to?

Blackwater fever | Concerned for autoimmune rxn w destruction of kidney tissue

RBCs infected with Falciparum malaria stick to capillary linings leading to what?

Capillary obstruction

Pt presents with cold skin temp but high internal malaria. What should you be concerned about?

Algid malaria (releated to Plasmodium falciparum)

How can Plasmodium falciparum be distinguished from Plasmodium vivax?

Plasmodium falciparum is non relapsing due to lack of hypnozoite stage and absence of Schuffners dots on microscopic eval

Pt presents w/ hx of mosquito bite and signs of necrosis, hemorrhages, extreme fever, mania, convulsions, and is at risk of death. What is the infecting species and what type of malaria are you concerned about?

Plasmodium falciparum | Cerebral malaria

Gastric falciparum malaria from the Plasmodium falciparum species leads to what sxs?

Frequent vomiting

On microscopic eval of blood of a malaria infected pt you see erythrocytes with double or multiple ring stages, crescent shaped gametocytes, and Maurer's clefts. What organism are you concerned about?

P. falciparum

On microscopic eval of blood of a malaria infected pt you see young trophozoites and gametocytes but not schizonts in the periphery. What infecting organism are you concerned about?

P. falciparum

How is P. falciparum controlled?

Protection from mosquitos (nettings, insecticides, repellants)

What malaria organism has the following characteristics: Infects older RBCs Paroxysms every 4th day Zoonotic from primate reservoirs

P. malariae

On microscopic eval of blood of a malaria infected pt you see trophozoites (basket and band shaped) and schizonts (rosette shaped). What infecting organism are you concerned about?

P. malariae

What malaria organism has the following characteristics: Similar to vivax malaria Relapses common Common to W coast of Africa

P. ovale

What malaria organism has the following characteristics: Zoonotic May be life-threatening if heavy parasite burden Common to SE Asia

P. knowlesi

Why is medication targeting Duffy antigen becoming less effective?

Increasingly independent binding to Duffy antigen

What is the main cause of drug resistance for malaria organisms?

Efflux pumps

What is the causative agent of Babesiosis (Nantucket island fever)

Babesia microti

What does Babesia microti infect?

RBCs

When do you have increased transmission of Babesia microti?

Warmer months/ summer

Lack of ability to test for Babesia microti in the blood leads to issues why?

Transmission through blood donation

What is the vector for Babesia microti?

Deer tick

Pt presents w small pinpoint lesions and are diagnosed w anemia. What organism should you be suspicious of?

Babesia microti

Babesia microti often presents with a co-infection of what disease?

Lyme disease

If under microscopic examination you note a "cross like" morphology in RBCs, what infecting organisms should you be concerned for?

Babesia microti

How is infection with Babesia microti controlled?

Insect repellants when outdoors

How did water treatment plants affect infection with polio?

Shifted from infants getting infected (fewer complications) to children getting infected

What disease affects the brain stem and cerebellum?

Rabies

What disease affects the cerebral cortex and cerebellum?

Creutzfeldt-Jakob encephalitis

What is the only disease that you vaccinate after exposure for?

Rabies

What disease affects the anterior horn cells and bulbar motor nuclei?

Poliomyelitis

What disease is associated with asymmetric flaccid paralysis?

Poliomyelitis

What causes asymmetric flaccid paralysis seen with poliomyelitis?

Destruction of motor neurons in spinal cord

What is the virus responsible for poliovirus?

Picorna virus

What are the 5 main clinical syndromes of the polio virus infection?

1. Inapparent infection (most common) 2. Abortive illness 3. Nonparalytic poliomyelitis 4. Paralytic poliomyelitis 5. Post polio syndrome

What is the rarest/ more severe manifestation of the polio virus infection?

Paralytic poliomyelitis

What device is used for pts with paralytic poliomyelitis to continue breathing?

Iron lung

What polio syndrome is associated with muscle weakness, pain and fatigue in paralyzed polio pts?

Post polio syndrome (30 yrs post) | Only in paralyzed pts

In a pt with post polio syndrome, has the latent polio virus returned?

No, remaining motor units of CNS react to overuse and fail

How can polio be prevented?

Inactivated polio vaccine (IPV) (Salk) | Live polio vaccine, trivalent oral polio vaccine (OPV)

Does the inactivated polio vaccine prevent infection?

No, prevents disease/ paralysis (not infection)

Why is the live polio vaccine (OPV) no longer used in the US?

Possibility for back mutation to wild type

Why is it important to continue to vaccinate against polio?

The polio virus is still present in some countries

What is the cause of the newest/ uncontrolled strain of polio?

Circulating vaccine-derived polioviruses (cVDPVs)

What arbovirus is the most concerning in the US and how is it transmitted?

West Nile virus | Vector= mosquito, tick

What is the reservoir for West Nile virus?

Animals

Are humans active hosts for arbovirus (West Nile virus)?

No (dead end hosts)

What is the most concerning agent of disease for arbovirus?

Flavivirdae group (yellow fever group)

What is important in the treatment/ prevention of arbovirus?

Break chain of transmission

Pt presents w fever, HA, vertigo, photophobia, nausea, vomiting, confusion/ personality changes, focal/ general seizures. What are you concerned for?

Arbovirus

What serious complication is caused by WNV?

Encephalitis

What population is typically affected by WNV?

Older pts

What time of year is WNV most prevalent?

Summer/ fall (higher mosquito activity)

Does WNV have the potential to cause viral encephalitis?

Yes

What test is used for the dx of WNV?

MAC-ELISA (look for IgM antibody)

In pts with yellow fever, dengue, Japanese encephalitis St Louis encephalitis viruses, what should you beware of when performing tests such as MAC-ELISA?

Antigenic cross reactions

Vaccination against yellow fever and/ or Japanese encephalitis may induce what?

Long-lasting positive IgM titers (for 9 mos past vaccine) | *travel hx important*

What test is best for dx of Zika?

RT-PCR

For all arboviruses besides Zika, what is the best dx test?

IgM ELISA

How is infection w arbovirus prevented?

Interrupt chain of transmission

What is the major concern w Zika virus?

Teratogenic potential and GBS

What are most US cases of Zika virus associated with?

Travel

How can Zika virus be prevented?

Mosquito avoidance and pt edu (including potential to transmit as STI)

What is the target of rabies disease?

Salivary glands

Only touch with rabid animal can cause what?

Cryptic rabies

What affected organism exhibits a "furious" excitatory phase?

Dogs only | Humans experience anxiety and apprehension hydrophobia

Pt presents w mild fever, pharyngitis, HA, and abnormal sensations such as pain and burning. What should you be concerned for?

Rabies

What phase of rabies is characterized by coma, hypotension, and possible death?

Paralytic phase

How is rabies dx'd?

Exposure to bite + sxs

In what case do you always treat/ should you be especially cautious for with regards to rabies?

Contact w a bat

Microscopy shows a "bullet shaped" organisms. What should you be concerned about?

Rabies

What "tx" for rabies has failed as often as it has succeeded?

"Milwaukee" protocol

How is rabies prevented in animals?

Prophylactic vaccination in companion/ herd animals

How is rabies treated in humans?

Vaccine (HDCV) + hyperimmune serum after contact w reservoir animal

What are the 2 broad categories of CNS infections?

Meningitis and encephalitis

What CNS infection is defined as inflammation resulting from an infection within the subarachnoid space?

Meningitis

What CNS infection is defined as inflammation in the parenchyma?

Encephalitis

What organism-dependent skin complication can occur from CNS infections?

Abscess formation

What time frame defines acute v chronic meningitis?

``` Acute = hours to several days Chronic = ≥ 4 weeks (w over exaggerated immune response) ```

What is the danger with respiratory pathogens?

Can enter blood and cause CNS infection

Why has the cause of bacterial meningitis infections shifted from H. influenzae to S. pneumoniae?

Vaccine against H. influenzae | S. pneumoniae is cause of resp infections which lead to CNS infections

Why has the incidence of meningitis declined significantly over time?

Vaccines | Screening of pregnant women for GBS (group B strep)

What can manifest as an "aseptic" case of meningitis (and classified as virus) due to difficulty in making a positive ID of pathogen?

Bacterital meningitis

Which type of meningitis is usually caused by organisms able to colonize the resp tract?

Community acquired

Which type of meningitis results after iatrogenic procedures or in patients with altered immune status and often GI/ skin pathogens?

Hospital acquired

What is step 1 in pathogenesis of bacterial meningitis? 1. 2. Entry into blood stream 3. Penetration of BBB 4. Release of inflammatory cytokines 5. WBC diapedesis into CSF 6. Increased permeability of BBB 7. Exudation of serum 8. Edema, increased intracranial pressure, altered BF

Mucosal colonization

What is step 2 in pathogenesis of bacterial meningitis? 1. Mucosal colonization 2. 3. Penetration of BBB 4. Release of inflammatory cytokines 5. WBC diapedesis into CSF 6. Increased permeability of BBB 7. Exudation of serum 8. Edema, increased intracranial pressure, altered BF

Entry into blood stream

What is step 3 in pathogenesis of bacterial meningitis? 1. Mucosal colonization 2. Entry into blood stream 3. 4. Release of inflammatory cytokines 5. WBC diapedesis into CSF 6. Increased permeability of BBB 7. Exudation of serum 8. Edema, increased intracranial pressure, altered BF

Penetration of BBB

What is step 4 in pathogenesis of bacterial meningitis? 1. Mucosal colonization 2. Entry into blood stream 3. Penetration of BBB 4. 5. WBC diapedesis into CSF 6. Increased permeability of BBB 7. Exudation of serum 8. Edema, increased intracranial pressure, altered BF

Release of inflammatory cytokines

What is step 5 in pathogenesis of bacterial meningitis? 1. Mucosal colonization 2. Entry into blood stream 3. Penetration of BBB 4. Release of inflammatory cytokines 5. 6. Increased permeability of BBB 7. Exudation of serum 8. Edema, increased intracranial pressure, altered BF

WBC diapedesis into CSF

What is step 6 in pathogenesis of bacterial meningitis? 1. Mucosal colonization 2. Entry into blood stream 3. Penetration of BBB 4. Release of inflammatory cytokines 5. WBC diapedesis into CSF 6. 7. Exudation of serum 8. Edema, increased intracranial pressure, altered BF

Increased permeability of BBB

What is step 7 in pathogenesis of bacterial meningitis? 1. Mucosal colonization 2. Entry into blood stream 3. Penetration of BBB 4. Release of inflammatory cytokines 5. WBC diapedesis into CSF 6. Increased permeability of BBB 7. 8. Edema, increased intracranial pressure, altered BF

Exudation of serum

``` What is step 8 in pathogenesis of bacterial meningitis? 1. Mucosal colonization 2. Entry into blood stream 3. Penetration of BBB 4. Release of inflammatory cytokines 5. WBC diapedesis into CSF 6. Increased permeability of BBB 7. Exudation of serum 8. ```

Edema, increased intracranial pressure, altered BF

What is the most common pathway for a pathogen gaining access to the CNS?

Invasion of the bloodstream and seeding of the CNS

Besides invasion of the bloodstream and seeding of the CNS, what are the other 2 pathways for a pathogen gaining access to the CNS?

Retrograde neuronal pathway | Direct contiguous spread

What allows fluid, WBCs and other immune components to enter the blood during a CNS infection?

"Leaky" blood vessels

What is the classic triad of sxs for CNS infections?

Fever, HA, neck stiffness

What would you expect to see with CSF glucose levels in a pt with a CNS infection?

Decreased; organism uses as energy source

Neonatal meningitis can be caused by what factors?

Neonatal or maternal factors

What are the most important signs/ sxs seen with neonatal bacterial meningitis?

Bulging fontanelle, high pitched cry, hypotonia, paradoxic irritability

What is paradoxic irritability seen with neonatal bacterial meningitis?

Quiet when stationary and crying when held

How can neonatal bacterial meningitis be classified that differentiates it from meningitis seen in adults?

Hyperthermia +/- GI disturbance

What are the predominant agents of neonatal bacterial meningitis, and are they G+ or G-?

``` Streptococcus agalactiae (G+) (GBS) E. coli (G-) Listeria monocytogenes (G+) ```

Screening pregnant mothers for GBS and routine abx prophylaxis for culture + women contributes to what?

Prevention of neonatal bacterial meningitis

Does a child who survives neonatal bacterial meningitis have long term effects?

Yes, usually permanent defects

What is the most common cause of neonatal bacterial meningitis?

Streptococcus agalactiae (GBS)

Which causative agent of neonatal bacterial meningitis will display gray-white colonies with a narrow zone of beta-hemolysis on microscopy?

S. agalactiae (GBS)

When do most cases of neonatal bacterial meningitis caused by S. agalactiae occur?

Transmitted during delivery (remainder acquired postpartum)

Capsular polysaccharide, hyaluronidase, collagenase, and hemolysin are virulence factors for what pathogen? (dangerous bc neonates are IMC)

S. agalactiae (GBS)

When can S. agalactiae (GBS) be seen in adults?

IMC

With early onset neonatal bacterial meningitis, are maternal obstretric complications common or uncommon?

Common

When do sxs develop with with early onset neonatal bacterial meningitis?

During first 5 days of life

What type of neonatal bacterial meningitis is characterized by bacteremia, pneumonia, and meningitis?

Early onset

What type of neonatal bacterial meningitis leads to systemic effects (bone/ joint infections, bacteremia w meningitis) and is often fatal?

Late onset

How is infected by S. agalactiae diagnosed?

Lab tests detect CAMP factor (only works 25% of the time)

How is S. agalactiae definitely diagnosed?

Isolation from blood, CSF

Source of E. coli (causing bacterial meningitis) is rectal colonization of mother's vagina and NOT what?

An endogenous infection

What is the morphology of E. coli?

G- encapsulated bacillus

What is the most common cause of bacterial meningitis, is most common agent in elderly, and is most common with recurrent meningeal infections?

S. pneumoniae

What is the morphology of H. influenzae (causing bacterial meningitis)?

Non-motile, G- coccobacillus

What causative agent of bacterial meningitis displays a usual pattern of several days of mild antecedent infection followed by deterioration, signs and sxs of meningitis?

H. influenzae

What is the morphology of L. monocytogenes (causing bacterial meningitis)?

G+ motile coccobacillus, non-fastidious, facultative IC pathogen

What pathogen causing bacterial meningitis is common in foodstuffs?

L. monocytogenes

What temps allows survival of L. monocytogenes?

Low temps (freezer, refrigerator)

What pathogen is considered the "exception" because it is not commonly a resp infection and is more common in summer?

L. monocytogenes

What are the 2 primary virulence factors of L. monocytogenes?

Lipopolysaccharide-like surface component | Listeriolysin O

What virulence factor of L. monocytogenes has the following characteristics: Antiphagocytic Presumably responsible for induction of complement- depdendent hemolytic antibodies

Lipopolysaccharide-like surface component

What virulence factor of L. monocytogenes has the following characteristics: Disrupts phagolysosome membrane Inhibits antigen processing Induces apoptosis

Listeriolysin O

Why is pathogenesis listeriosis dangerous in an IMC host?

IMC cannot eliminate = IC and EC multiplication and systemic disease

What are the 2 main clinical manifestations of listeriosis?

Sepsis and meningitis

If you note "tumbling" motility in hanging drop preparation of a pathogen, what should you be concerned for?

Listeriosis

How is listeriosis diagnosed?

DNA probe technology

What is the causative agent of meningococcal meningitis?

Neisseria meningitidis

What pathogen has a morphology that is fastidious, G-, kidney bean-shaped diplococcus and encapsulated?

Neisseria meningitidis

What is the most important serogroup of Neisseria meningitidis?

Who is the only reservoir for Neisseria meningitidis and what does infection require?

Humans | Close contact

Pt presents with a skin rash consisting of petechiae and pink macules that is widespread and erupted within hours. What are you concerned for?

Meningococcemia

If you note a + tumbler test in which the pts rash does NOT change color (aka is non-blanching), what should you be concerned about?

Meningococcal meningitis

Thayer-Martin agar is selective for what pathogen due to presence of antibiotics?

Meningococcal meningitis

Why don't you give a group B vaccine with the A,C,Y,W135 vaccine on the same day in the same arm for prevention of Meningococcal meningitis?

Causes autoimmune rxn

What is the pathogenesis for reactivation/ secondary TB after progression from caseous lesions with necrosis?

Erode and discharge TB bacilli into bronchi (infectious) > erode blood vessel > hematogenous spread

What are the following used for? Purified MTB protein derivative (PPD) in skin test Boosters id'd by 2nd administration BCG and NTM false pos

Serial screening programs to id latent TB

How does infection w MAC occur?

Infection through contaminated water or food

When can measles be especially severe?

Malnourished and/or vitamin A deficient persons

How does measles cause encephalitis?

Viremia, dissemination to other tissues by monocytes

What disease multiples in respiratory epithelium and lymph nodes?

Measles

What are the 4 stages of measles?

1. Incubation period (10-14 days) 2. Prodromal stage 3. Rash 4. Resolution

At what point do you have resolution of measles?

Rise in antibody titers, viremia stops, rash fades in same order it appears

Who are the only known hosts of measles?

Humans and monkeys

When is the measles vaccine given?

``` Initiation before school entry 1st dose = 15 mos 2nd dose = 4-6 yrs Monovalent measles vaccine if under 15 mos and high exposure likelihood Booster sometimes required ```

How is rubella treated?

Symptomatic relief MMR Intravenous immunoglobulin (IVIG) "last ditch effort" if exposure of non-immune mother in 1st trimester

How is continued spread of HSV halted?

Cell and humoral immune processes (disseminates if absent)

Besides spreading via contact with vesicular fluid, saliva, and secretions, how else can HSV be spread?

Asx shedding possible

Where does the chickenpox virus replicate?

Regional lymph nodes (4-6 days) | Liver and spleen (secondary viremia at 10-14 days)

Who gets the zostavax vaccine?

Pts over 50 yo | High potency vaccine

What is the treatment for parvovirus?

``` Sx relief (non-steroidal anti-inflammatory agents) Immunoglobulin available for anemia patients ```

What topical tx is used for folliculitis?

Clindamycin ointment or benzoyl peroxide

What type of spores are microconidia and macroconidia?

Asexual

What dermatophytid species is the most common cause of tinea capitis, fluoresces when examined with a wood lamp and produce hyphae, micro/ macroconidia (large, spindle shaped, multicellular, thick walled)?

Microsporum species

What are the 3 most common pathogens responsible for Tinea pedis, Tinea corporis, Tinea cruris, and Tinea unguium?

E. floccosum, T. mentgrophytes, T. rubrum | Also M. canis for corporis, cruris, capitis

How can recurrent furuncles be prevented?

Liquid soap containing chlorhexidine/ isopropyl alcohol and maintenance abx

How can impetigo and ecthyma be managed?

Hygiene, wash with soap and water, topical abx ointment

How is scalded skin syndrome treated?

Prompt dx and therapy w penicillinase- resistant anti-staph abx

If scalded skin syndrome is extensive, how should it be treated?

Treat as for burns

How is erysipelas treated?

Oral or IV abx targeted against most likely agent

Is type 1 NF mono or poly microbic?

Type 1 = poly | Type 2 = mono

Is type 1 or 2 "flesh eating bacteria"/ strep gangrene?

Pt presents with a thick pink/ purple fluid filled bullae on leg that is not tender. What are you concerned for?

What promotes split and invasion of nearby tissue in pts with NF?

Production of exotoxins and insoluble H2 gas

On surgery, infected muscle is dark red to black, non-contractile and does not bleed when cut. What should you be concerned for?

Clostridial myonecrosis

What is the treatment for Lyme disease?

Sx: amoxicillin or doxycycline for 10-21 days

What are the 4 possible courses of viral hepatitis?

1. Subclinical and anicteric 2. Typical acute icteric hepatitis 3. Fulminant hepatitis 4. Chronic hepatitis

Which course of viral hepatitis is associated with a high fatality rate?

Fulminant hepatitis

How is the subclinical and anicteric course of viral hepatitis recognized?

Seroconversion

What does the incubation period of typical acute icteric hepatitis course represent?

Dose dependent range

While the prodrome or pre-icteric phase of hepatitis is marked by fatigue, malaise, and anorexia, what is the icterus phase marked by?

Dark urine, jaundice, hepatomegaly, elevation of serum enzymes

What phase of the typical acute icteric hepatitis course includes disappearance of jaundice and other sxs?

Convalescent phase

What is the treatment for HAV?

Bed rest, reduction of activities, hydrated, good nutrition, avoid hepatotoxins

When should a pt with HAV be hospitalized?

If IV fluids needed or there is evidence of deteriorating liver function

What are the following HBV antigens associated with? HBsAg HBcAg HBeAg

HBsAg- surface antigen HBcAg- core antigen HBeAg- surface antigen + pt infectious

HBV replicates almost exclusively where?

In the liver

Who is Colleen's best friend?

Abbey <3

Exam 2 Flashcards

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