LOs: 17-20 Flashcards Preview

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Flashcards in LOs: 17-20 Deck (32):
1

17 Epidemiology of STIs

20M new infections every year

Young ppl (15-24) account for 50%

Increasing resistance in Neisseria gonorrhea

Increasing sexual transmission of Hepatitis C in the MSM population

2

17 Syndromes of STIs in Females:
Causes:

No symptoms, but at risk for STD

Vaginitis/vaginosis

Cervicitis

Pelvic inflammatory disease

Genital ulcer or vesicle

Papular genital lesions

C. trachomatis (Ct), N. gonorrhoeae (Ng), HPV, HSV, HIV, HBV, others

Yeast (Y), bacterial vaginosis (BV), Trichomonas vaginalis (TV)

C. trachomatis, N. gonorrhoeae, HSV

C. trachomatis, N. gonorrhoeae, Enterobacteriaceae, anaerobic bacteria
HSV, Treponema pallidum, Haemophilus ducreyi

HPV, Molluscum contagiosum, condylomata (CL) (secondary syphilis)

3

17 Syndromes of STIs in Females:
Symptoms/Signs:

No symptoms, but at risk for STD

Vaginitis/vaginosis

Cervicitis

Pelvic inflammatory disease

Genital ulcer or vesicle

Papular genital lesions

None or subtle

Y: itching, redness, clumpy white discharge BV: amine odor, discharge
TV: itching, redness, discharge

Genital discharge, lower abdominal pain, intermenstrual bleeding

Can be subtle
Lower abdominal pain, deep dyspareunia, abnormal bleeding, tenderness on cervical motion

Painful or painless ulcers or vesicles + inguinal lymphadenopathy

HPV: usually subclinical; warts can be cauliflower- like
Molluscum: round, umbilicated papules CL: moist papules accompanied by generalized rash

4

17 Syndromes of STIs in Females:
Treatment:

No symptoms, but at risk for STD

Vaginitis/vaginosis

Cervicitis

Pelvic inflammatory disease

Genital ulcer or vesicle

Papular genital lesions

If known contact with STD, treat according to contact guidelines for index STD regardless of findings.
Otherwise, treat according to results of screening test.

Y: Topical imidazole or oral fluconazole
BV or TV: metronidazole

Give empirical treatment for Ct and Ng.

Treat with antibiotic regimen active against all major causes
Hospitalize if (1) surgical
emergency cannot be ruled out, (2) severe illness, (3) tubo-ovarian abscess, (4) failed oral therapy

HSV: acyclovir Syphilis: benzathine penicillin

HPV: liquid nitrogen, podophyllotoxin, others Syphilis: benzathine penicillin

5

17 Syndromes of STIs in Males:
Causes:

No symptoms, but at risk for STD

Urethritis

Epididymitis

Proctitis

Genital ulcer or vesicle

Papular genital lesions

C. trachomatis (Ct), N. gonorrhoeae (Ng), HPV, HSV, HIV, HBV, others

C. trachomatis (Ct), N. gonorrhoeae (Ng), HSV

C. trachomatis, N. gonorrhoeae, Enterobacteriaceae

C. trachomatis,
N. gonorrhoeae, HSV

HSV, Treponema pallidum, Haemophilus ducreyi

HPV, Molluscum contagiosum, condylomata (CL) (secondary syphilis)

6

17 Syndromes of STIs in Males:
Symptoms/Signs:

No symptoms, but at risk for STD

Urethritis

Epididymitis

Proctitis

Genital ulcer or vesicle

Papular genital lesions

None or subtle
Urethral discharge, dysuria, irritation of distal urethra or meatus

Unilateral scrotal swelling and/or tenderness

Anorectal pain (+
discharge), tenesmus

Painful or painless ulcers or vesicles + inguinal lymphadenopathy

HPV: usually subclinical; warts can be cauliflower- like
Molluscum: round, umbilicated papules CL: moist papules accompanied by generalized rash

7

17 Syndromes of STIs in Males:
Treatment:

No symptoms, but at risk for STD

Urethritis

Epididymitis

Proctitis

Genital ulcer or vesicle

Papular genital lesions

If known contact with STD, treat according to contact guidelines for index STD regardless of findings.
Otherwise, treat according to results of screening test.

Give empirical treatment for Ct and Ng.

Give empirical treatment for Ct and Ng, and consider use of agent effective against urinary tract pathogens.

If no indication of HSV, treat empirically for Ct and Ng.
HSV: acyclovir Syphilis: benzathine penicillin

HPV: liquid nitrogen, podophyllotoxin, others Syphilis: benzathine penicillin

8

17 Chlamydia trachomatis:

Biology & Life Cycle
- Type of pathogen
- Encodes...
- Development cycle involves...

Epidemiology

Classification
- Serovars
- Chlamydophila

Pathogenesis
- LGV vs. non-LGV
- Inflammation
- Type of infection

Diagnosis (4)

Treatment
- Normal
- Pregnant
- LGV

- Obligate intracellular pathogen, energy parasite
- Encodes major outer membrane protein
- Extracellular elementary body (EB) & replicative reticulate body (RB): EB prevents fusion of endosome w/ lysosomes, reorganizes into RB, synthesizes DNA/RNA/proteins, fills endosome w/ progeny, transforms into new EBs, infects new cells

Young, African Americans from the south (most asymptomatic)

- Serovars A-K: trachoma, cervicitis, PID, etc.
- Serovars L1-L3: lymphogranuloma venereum (LGV)
- Chlamydophila pneumonia: bronchitis & pneumonia
- Chlamydophila psittaci: zoonotic, pneumonia (psittacosis)

- LGV cause systemic infection in lymphoid tissues, non-LGV confined to mucosal epithelial cells
- Chronic inflammatory process leads to epithelial cell necrosis, fibroblast proliferation, & eventual scar tissue formation
- Casues prolonged & often subclinical infection

- NAAT
- Culture
- Immunofluorescence
- Serology

- Normal: Azithromycin (single dose) or Doxycycline (1 week)
- Pregnant: Azithromycin (single dose) or Amoxicillin (1 week)
- LGV: Doxycycline (3 weeks)

9

17 Chlamydia trachomatis:
Clinical Manifestations:

Infections in Males (5)

Infections in Females

Lymphogranuloma Venereum (LGV)

Infections in Newborns

- Urethritis: dysuria, clear/mucopurulent urethral discharge
- Epididymitis
- Reiter's syndrome: arthritis, urethritis, & conjunctivitis
- Transmission to women
- Pharyngeal/rectal infection

- Urethritis, cervicitis: dysuria/pyuria, cervicovaginal discharge, abdominal pain, intermittent bleeding, dyspareunia, mucopurulent discharge
- Ascending infection: endometritis, salpingitis
- Bartholinitis: infection of Bartholin's ducts
- Pelvic Inflammatory Disease (PID): ascends from vagina & cervix, lower abdominal pain, vaginal discharge, uterine bleeding, dysuria, dyspareunia, nausea, vomiting, fever
- Fitz-Hugh-Curtis syndrome: perihepatitis

- Biovar LGV (L1-L3)
- Small painless papule or ulcer at site of infection (penis or vagina)
- Enlarged painful lymph nodes
- Procitis: rectal damage, anal pruritis, mucoid rectal discharge, fever, rectal pain, tenesmus

- Conjunctivitis: major manifestation, watery purulent ocular discharge, 5-14 days after birth
- Pneumonia: gradually worsening nasal congestion & cough, 4-11 weeks after birth

10

17 Syphilis:

Pathogen
- Causative agent
- Characteristics

Epidemiology
- When most contagious
- Rates

Pathogenesis
- Infection
- Primary Syphilis
- Secondary Syphilis
- Tertiary Syphilis

Diagnosis

Treatment & Prevention
- Primary, Secondary, & Early Latent
- Late Latent & Tertiary
- Neurosyphilis
- Pregnant Women

- Treponema pallidum
- Treponemes: tapered, thin spiral rods, corckscrew locomotion

- Most contagious during primary & secondary stages
- Rates increasing in men, low socioeconomic, African American, heterosexual population in Southeast

*Infection
- Penetrates abraded skin & mucous membranes or transplacental
- Disseminates to lymphatics & blood stream within hours to days
*Primary Syphilis (Chancre)
- Lesions appear when concentration of ~107 per mg of tissue reached
- Median incubation: 3 weeks
*Secondary Syphilis
- Disseminated stage: greatest number of treponemes are present in body
- Treponemes seen in different tissues especially skin & lymph nodes
*Tertiary Syphilis
- Tertiary lesions consist of gummas, cardiovascular, & CNS disease (CNS invasion can occur at any time)
- Tertiary lesions result in irreversible tissue destruction

- History & physical exam
- Darkfield microscopy
- Serologic tests
-- Non-treponemal tests: non-reactive w/ time, false positives (VDRL, RPR)
-- Treponemal tests: should have standard non-treponemal test to guide decisions (FTA-ABS, MHA-TP)

*Primary, Secondary, & Early Latent
- Benzathine PCN G x 1 dose IM
- Doxycycline twice daily x 14 days (if PCN allergy)
*Late Latent & Tertiary
- 3 doses of Benzathine PCN G at 1 week intervals IM
- Doxycycline twice daily x 28 days (if PCN allergy)
*Neurosyphilis
- Aqueous crystalline PCN G IV x 10-14 days
*Pregnant Women
- ONLY PCN, desensitize if allergic

11

17 Syphilis:
Clinical Manifestations:

Primary Syphilis

Secondary Syphilis

Latent Syphilis

Tertiary Syphilis

Congenital Syphilis

PS
- Primary lesion develops at site of inoculation
- Initially a papule which then ulcerates
- Chancre is painless & has a clear base
- Associated w/ regional lymphadenopathy
- Can be seen in the penis, vagina, perianal/rectal area, & tongue
- Heals spontaneously
- Serologic tests may not be positive

SS
- Typically occurs 2-8 weeks after the disappearance of the chancre
- Rash & lymphadenopathy are the most common manifestations
- Rash will often but not always involve the palms & soles
- Condyloma lata (~10% of cases) are raised, enlarged lesions usually seen in warm, moist areas
- Mucous patches & alopecia may also be seen in ~5% of cases
- Liver & kidney involvement have been reported
- Serologic tests are usually highest at this stage

LS
- Lesions of primary & secondary syphilis resolve even w/o treatment
- At this stage, no lesions are apparent, although lesions of secondary syphilis may occur within the 1st year in 25% of cases
- Early latent: <1 year
- Late latent: ≥1 year
o Not thought to be infectious (except in pregnancy)
o Longer treatment required

TS
- ~30% of untreated pts progress to tertiary syphilis
- Endarteritis of the vaso vasorum of the aorta can lead to aortits & aneurysm formation (usually in the ascending aorta)
- Chronic inflammation of coronary arteries lead to narrowing/stenosis
- Gummatous syphilis is characterized by indolent, destructive lesions of the skin, soft tissue, & bony structures

CS
- Transmission occurs during any stage (higher in P&S)
- Infection can occur at any stage of the pregnancy
- Stillbirth, death soon after birth, physical deformities, neurologic complications
- Neonatal disease: usually premature, hepatic/splenic involvement, rash, pneumonia
- Late onset disease: bone malformation (saddle nose, saber shin), teeth malformation (Hutchinson’s teeth), & neurlogic deficits

12

18 Zoonoses:

Zoonotic Infections

Reservoir

Vector

Transmission

Severity

Control

Xenozoonosis

transmitted from animals to humans

where etiologic agent resides

medium (insect or other) transferring the etiologic agent between the animal reservoir and the human host

via ingestion, animal bites, or arthropod vectors

benign, low-grade infection

difficult due to existence of a mobile animal reservoir, easily spread
- Veterinary medicine
- Sanitary engineering
- Entomologic management
- Wildlife management
- Behavioral changes

transmission of infectious diseases from animal tissue transplantation

13

18 Factors Influencing Zoonoses:

Host (5)

Pathogen (5)

- Improved diagnostics
- Recreational travel to rural areas
- International travel
- Population displacement due to warfare
- Homelessness

- High population of reservoir host
- New reservoir or transmission cycle
- Global climate change
- Translocation of reservoir host & ectoparasties
- Newly emerged or recognized organism

14

18 Hantavirus:

Biological Characteristics

Reservoirs

Transmission

Virulence Factors

Pathogenesis

Symptoms

Diagnosis

Treatment

Prevention

BC
- Bunyavirus
- Spherical, nucleocapsid, enveloped, (-) RNA
- Have viral-specific transcriptase
- Buds from golgi w/ 2 glycoproteins

R
- Urine, saliva, & feces of rodents (esp deer mice)

T
- Breathing in aerosols containing infectious material

VF
- 2 envelope glycoproteins determine host range (esp endothelial cells)
- Multiply infect host, excreted, survive dehydration

P
- Lasting immunity
- Invades respiratory route, replicates, spreads to heart/gut/liver/kidney/CNS
- T cell infiltrate w/o necrosis

S
- Fever, headache, malaise, myalgia, diarrhea
- Death from pulmonary edema (respiratory failure) & renal shutdown

D
- History/exposure
- Viral RNA

T
- IV fluid, Dialysis

P
- Avoid rodent infested areas

15

18 Rabies Virus:

Biological Characteristics

Reservoirs

Virulence Factors

Pathogenesis

Symptoms

Diagnosis

Treatment

Prevention

BC
- Rhabdovirus
- 1 single-stranded (-) RNA, helical capsid, nucleocapsid, envelope
- Large bullet shaped virions

R
- Dogs, cats, pets, skunks, raccoons, foxes, bats

VF
- Neuronal tropism
- Targets ACh receptor

P
- Animal bites muscle, spreads to CNS, migrates to organs (esp salivary glands)

S
- Abnormal sensation at bite site
- Confusion, lethargy, paresis, increased salivation, irrational aggressive actions,
- Hydrophobia, seizures, paralysis, coma, encephalitis, death

D
- History
- Anti-rabies IgM, IgG
- Nuchal skin biopsy, saliva testing
- Confirmed in suspected animal by direct fluorescent antibody test of brain tissue

T
- Post-exposure rabies prophylaxis (PEP): wound cleansing, human rabies immune globulin (HRIG), HDCV

P
- Pre-exposure immunization w/ HDCV

16

18 Rickettsia rickettsii:

Biological Characteristics

Reservoirs

Transmission

Most Common Disease

Virulence Factors

Pathogenesis

Symptoms

Diagnosis

Treatment

Prevention

BC
- Rickettsiaceae
- Obligate intracellular pathogens
- Too small to gram stain but gram(-) structure

R
- Ticks of Dermacentor species

T
- Arthropod vectors (tick bite)
- Transovarial transmission from femal eto offspring
- Ticks feeding on small mammals

MCD
- Rocky Mountain Spotted Fever (throughout North & South America)

VF
- Direct actin reorganization (filopodia enhances spread)
- Phospholipases, proteases, and membrane peroxidation result in host cell damage
- Energy parasites

P
- Introduced by bite of adult tick (or crushing)
- Spread via lymph/blood
- Invades many mammalian cells but mainly vascular endothelium
- Lysis of endothelial cells leads to rupture of capillaries & small vessels

S
- Rash localized to extremities
- Fever, malaise, severe frontal headache, myalgia and vomiting
- Abdominal pain, diarrhea, conjunctivitis, mental confusion, meningitis, respiratory difficulties, renal
dysfunction, and/or myocarditis
- Lysis of endothelial cells leads to endothelitis

D
- History/exposure
- Culture
- Immunostaining
- Weil-Felix test w/ Proteus vulgaris antigens

T
- Doxycycline (early stages)

P
- Public awareness

17

18 Borrelia burgdorferi:

Biological Characteristics

Reservoirs

Transmission

Most Common Disease

Virulence Factors

Pathogenesis

Symptoms

Diagnosis

Treatment

Prevention

BC
- Spirochetes, endoflagella ("corckscrew"), thin, darkfield microscopy
- Gram(-) structure

R
- Rodents
- In Southern New England, Mid Atlantic states, & coastal/wooded California & Oregon

T
- Tick vector (Ixodes: larva, nymph, adult)

MCD
- Lyme disease

VF
- Osps (surface lipoproteins, differentially expressed, important for attachment/adhesins)
- Plasmids for Osp expression

P
- Injected during tick bite (needs >48 hours to transfer spirochetes)
- Local replication, widespread dissemination
- Local inflammatory reaction
- Early: bull's eye expanding rash, malaise, fatigue, headache, fever, chills, myalgia
- Early-Disseminated: cranial neuropathy, meningitis, radiculoneuropathy, iritis, encrotizing retinis, cardiac dysfunction
- Late: oligoarthritis, dermatologic syndromes, neurologic demylination

D
- History
- Culture
- Serologic tests
- 2-tiered approach: immunoassay or immunoluorescent assay + Western immunoblot (confirm positive testing)

T
- Early: doxycycline, amoxicillin
- Late: IV ceftriaxone

P
- Environmental modifications
- Personal protection
- Tick checks

18

19 Clues to when an infection/outbreak may be due to intentional exposure

large epidemic with severe illness and high death rate among
people who are otherwise fairly healthy

likely presenting symptoms would be respiratory

if an organism was identified that wasn’t normally present in that part of the country or the world

simultaneous outbreaks around the country or organisms with an unusual pattern of antibiotic resistance

19

19 Biological threat from category A agents

Easily obtained & spread

High mortality

Public panic

Likely to cause fatal disease

20

19 Anthrax:

Microbiology

Vector

Transmission

Clinical Features

Virulence Factors

Treatment

Contagious?

Other

M
- Bacillus anthracis
- Gram positive, spore-forming bacilli
- Non-hemolytic, medusa's head/come'ts tail

V
- Livestock

T
- Exposure to infected animals/products
- Injection drug users
- Handling rums made of animal skins
- No person-to-person

CF
- Cutaneous (95%): exposure of abraded skin to spores, purpitic painless papule, black eschar, enlarged lymph nodes
- Inhalational (5%): flu-like, mediastinal widening, hemorrhagic mediastinitis, hemorrhagic meningitis
- GI (sporadic): uncooked meat, GI symptoms

VF
- Capsule (antiphagocytic, polyglutamic acid)
- Exotoxins
-- Edema toxin (affects cell function)
-- Lethal toxin (affects signal transduction)

T
- Cutaneous: doxycycline or ciprofloxacin
- Inhalational/GI: Ciprofloxacin, linezolid, Meropenem (meningitis), Clindamycin (no meningitis)
- Post-exposure prophylaxis: vaccine, doxycycline, levofloxacin, ciprofloxacin
- Raxibacumab
- Pleural effusion drainage
- Vaccine

C
- No

O
- Amerithrax 2001 attacks

21

19 Tularemia:

Microbiology

Vector

Transmission

Clinical Features

Virulence Factors

Treatment

Contagious?

Other

M
- Francisella tularensis
- Gram negative cocco-bacillus
- Facultative intracellular pathogen
- Doesn't take many organisms to cause disease

V
- Rabbits, Ticks, Flies

T
- Tick bite
- Contaminated animal products or water
- No person-to-person transmission

CF
- Ulceroglandular, Pharyngeal, Pneumonic, Oculoglandular, Typhoidal, Glandular

VF
- Capsule
- FPI

T
- Streptomycin
- Also gentamicin & doxycycline
- No vaccine

C
- No

O
- Martha’s Vineyard

22

19 Plague:

Microbiology

Vector

Clinical Features

Virulence Factors

Treatment

Contagious?

Other

M
- Yersinia pestis
- Gram negative bacillus
- Bipolar staining, "safety pin"

V
- Rodents, Fleas

CF
- Bubonic: most common, fevers, chills, weakness, headache, painful swollen lymph nodes
- Pneumonic: infection of lungs, fever, cough, difficulty breathing, bloody sputum
- Septicemic: generalized (bloodstream)

VF
- LPS,
- Type III secretion system
- Plasminogen activator

T
- Streptomycin
- Also gentamicin, doxycycline, ciprofloxacin (also for PEP)

C
Yes

O
SW US

23

19 Smallpox:

Microbiology

Vector

Transmission

Clinical Features

Treatment

Contagious?

M
- Variola major/minor
- Orthopox virus

V
- Human as only host
- Eradicated

T
- Most contagious from onset of rash until scabs have healed
- Droplet nuclei, direct contact, fomites

CF
- Centrifungal rash
- Lesions of same age
- Contagious after rash appears

T
- Cidofovir
- Isolation in a negative pressure room
- Vaccine: Dryvax (calf skin, before 2001) & ACAM (in vero, current)
-- Contraindications: immunodeficiency, skin condition, pregnancy
-- Adverse reactions: eczema, vaccinia, encephalitis

C
Yes

24

19 VHFs:

Microbiology

Vector

Transmission

Clinical Features

Treatment

Vaccine

Contagious?

Other

M
- RNA viruses

V
- Rodents for arena viruses

T
- Animals: aerosol, urine, feces, fomites (objects), saliva and ocular exposure
- Humans: contact with blood and body fluids

CF
- Fever, severe illness, petechiae, unexplained bleeding
- Shock

T
- Ribavirin for arenaviruses

C
- Yes

O
- Africa

25

20 Clinical Microbiology Laboratory:

Priorities (2)

Challenges (3)

- Accurate diagnosis
- Speed

- Managing large numbers of samples per day
- Managing individual samples
- Maintaining accuracy w/ quality control

26

20 Staining:

Examples

Advantages

Disadvantages

Gram stain, acid-fast stain, India ink preparation

Rapid, inexpensive

Lower sensitivity, not specific

27

20 Culture (bacteria):

Examples

Advantages

Disadvantages

MacConkey agar, eosin methylene blue (EMB)

high sensitivity, more information

overnight, not species-specific

28

20 Culture (virus):

Examples

Advantages

Disadvantages

cytopathic effect, immunofluorescent staining

specific identification

Slow, expensive, difficult to grow

29

20 Biochemicals:

Examples

Advantages

Disadvantages

tests on colonies (catalase, oxidase, PYR test), culture tests (tubes, API strips, Vitek cards)

species-specific

ambiguous for atypical behavior, expense

30

20 Antigen Testing:

Examples

Advantages

Disadvantages

PBP2a agglutination (MRSA); influenza and RSV rapid antigen tests

fast

low sensitivity

31

20 Nucleic acid amplification testing (NAAT):

Examples
- Rapid TB diagnostic
- Multiplex PCR
- 16S rRNA sequencing

Advantages

Disadvantages

- Rapid TB diagnostic (developing world, high sensitivity)
- Multiplex PCR (in parallel, rapid, qualitative)
- 16S rRNA sequencing (primers for conserved sequences, detecs unknown pathogens)

rapid, specific, quantitative

cost, labor, technically challenging, contamination, slow if sample sent to reference lab

32

20 Mass Spectrometry:

Components

Examples
- PLEX-ID
- Vitek MS

Advantages

Disadvantages

i. vaporization (ion source)
ii. measure mass-to-charge ratio (mass analyzer)
iii. abundance of molecule (mass detector)

- PLEX-ID: measures PCR, distinguishes by nucleotides
- Vitek MS: measures proteins, distinguishes peaks

rapid, general, direct from patient sample

overnight, sample prep, expense, sensitivity