Name the organism that causes a pneumonia with: typically upper lobar consolidation; currant jelly sputum; frequent in alcoholics; gram (-), oxidase (-); Bacillus
Klebsiella pneumonia
Give the phylogeny of Klebsiella pneumonia.
Gram negative, oxidase negative bacillus
member of the Enterobacteriacae
Name the organism that causes: coughing and choking spells; Posttussive emesis; CBC shows leukocytosis with high % lymphocytes; encapsulated, gram negative
Bordatella pertussis
Culture Bordatella pertussis on:
Blood agar
Whooping cough (Bordatella pertussis) also causes:
Hypoglycemia; Lymphocytosis; Blockade of immune effector cells; Increased histamine sensitivity
***ADP ribosylates Gi and inhibits it –> cAMP rises
Severe infection in immunocompromised persons consisting of bloody stool and spherical cysts in the stool with up to four nuclei is caused by:
Entamoeba histolytica
Entamoeba histolytica has what ROT?
Fecal-oral
What organism has nuclei with sharp karyosome and fine chromatin spokes?
Entamoeba histolytica
Give the organism:
Severe watery diarrhea in the immunocompromised population; intracellular spheres or arc-spahed merozoites under normal mucosa; Stool cysts are acid-fast and very small (oocysts)
Cryptosporidium Parvum
Infects brush border of the intestine - direct killing of brush border cells
Give the organism: Self-limiting diarrhea that can last weeks to months; Mostly tropical; Stool borne cysts are large and assymetrical (almond-shaped)
Isospora belli
LFA-1, expressed on the surface of WBCs, interacts with ____ to promote the arrest of WBCs on the surface of the endothelium, where they can travel to inflammation sites.
ICAM-1
LFA-1, expressed on the surface of WBCs, interacts with ____ to promote the arrest of WBCs on the surface of the endothelium, where they can travel to inflammation sites.
ICAM-1
CR3 is an integrin that binds to:
fibrinogen, ICAM-1 and iC3b encourages phagocytosis
Name the organism: Gram positive, gamma hemolytic cocci; vancomycin-resistant; grow in high salt environment;
VRE - Vancomycin-resistant enterococci
ie Enterococcus faecium, Enterococcus faecalis
Name the organism: Common in burn victims, catheterized patients, CF patients; gram negative, encapsulated oxidase positive; Bacillus
Pseudomonas aeruginosa
How does Pseudomonas aeruginosa resist aminoglycosides?
Enzymatically inactivate the drug via acetylation
Name the dx: Malformation of the 3rd and 4th pharyngeal pouches leading to thymic aplasia; cardiac anomalies
DiGeorge syndrome lack of mature T- cells lots of fungal infections
DiGeorge syndrome involves what genetic anomaly?
22q11 microdeletion
What accounts for the hypocalcemia seen in DiGeorge syndrome?
Lack of parathyroid glands
Rheumatic fever is what type of hypersensitivity reaction?
Type II (aka cytotoxic) IgG and IgM;
Autoantibodies bind antigens on tissues Strep pyogenes
What is the pathogenesis of rheumatic fever?
Infection with group A strep (Strep pyogenes) –> GAS incited antistreptococcal antibodies which cross-react with antigens of heart, dermis, joints etc.
Valvular heart disease is a common permanent complication.
Give the dx:
Pancarditis; Arthritis; Subcutaneous nodules; Chorea; Erythema marginatum
Rheumatic fever
Group A strep - Strep pyogenes
F+ to F- conjugation conferring antibiotic resistance is especially common in what kinds of bacteria?
Gram negative bacilli
Staph aureus and Pseudomonas aeruginosa are known to confer antibiotic resistance through what mechanism?
Transduction generalized - lytic phage specialized - temperate phage
Hives in type I hypersensitivity reactions are known to release what mediators?
leukotrienes B4, C4, D4; histamine
MG and Graves disease are noncytotoxic forms of what type of hypersensitivity rxn?
Type II
IgG only
Low glucose, and mostly lymphocytes in the CSF means what kind of meningitis?
Fungal ie Cryptococus neoformans
Name the organism:
Monomorphic, encapsulated, yeast; causes meningitis in immunocompromised patients
Cryptococcus neoformans
Rh incompatibility is what kind of hypersensitivity reaction?
Type II
cytotoxic 1st pregnancy no problems,
2nd pregnancy, erythroblastosis fetalis
How do you diagnose candida infection?
Germ tube test
demonstration of pseudohyphae in animal serum
Tx with fluconazole
CAMP test distinguishes between:
Group A and Group B Strep;
tests for bacitracin sensitivity
Identifies a partial hemolytic agent made by Strep agalactiae (group B)
Give the organism:
Beta-hemolytic, inhibited by bacitracin, causes PSGN
Group A strep, most likely Strep pyogenes
Strep pyogenes can cause what type of hypersensitivity reaction?
Type III - circulating immune complexes PSGN
Type II - Rheumatic fever
Herpes simplex encephalitis localizes to what part of the brain?
Temporal lobe
What is the drug of choice for uncomplicated S. pyogenes infection?
Beta lactam drugs, such as penicillins, cephalosporins
Prevent cell wall synthesis, prevent log phase
What drug class is indicated for people who allergic to beta lactams?
Macrolides
Give the organism:
Mini-epidemics; Common in kids; Pseudo-appendicitis; Bloody diarrhea with mucous
Yersinia enterocolitica
Shigella dysenteriae and Entamoeba histolitica share what invasion mechanism?
Invasion into the submucosa
Bloody diarrhea with neutrophils
Give the organism: Ulcer with black base; regional lymph node involevement; fever, chills, myalgias and arthralgias
Francisella tularensis - tularemia
Associate undulating fever with:
Brucella
Cowdry bodies
Herpes simplex virus type 1 (HSV-1) encephalitis is the most common cause of sporadic viral encephalitis in the United States.
The diagnosis of viral encephalitis is aided by demonstrating elevated lymphocytes in the cerebrospinal fluid. HSV-1 encephalitis is specific to the temporal lobes of the brain.
Cowdry type A inclusions can be seen in neurons and glia in HSV-1 encephalitis.
EBV Mononucleosis
Infectious mononucleosis is manifested in young adults by fever, malaise, lymphadenopathy, and splenomegaly.
Diagnosis is made by the heterophile antibody test (Monospot). Heterophile-positive mononucleosis is caused by the Epstein-Barr virus (EBV).
Enterococcus - E. faecalis and E. Faecium
Location
GI tract
Enterococcus - E. faecalis and E. Faecium
Gram stain
Gram positive
Enterococcus - E. faecalis and E. Faecium
Bile?
Resistant
Enterococcus - E. faecalis and E. Faecium
Plate on
Can grow on 6.5% NaCl
Enterococcus - E. faecalis and E. Faecium
Virulence factor
B. Faecium resistant to almost every antibiotic we have (VRE)
Faecalis more common;
Faecium more dangerous
Enterococcus - E. faecalis and E. Faecium
Diseases
UTI
Endocarditis
Biliary tree infection
Enterococcus - E. faecalis and E. Faecium
Treatment
If VRE, tx with Linezolid or Tigecycline
Staph aureus
Location
Colonizes nares
Staph aureus
Catalase
pos
Staph aureus
Coagulase
pos
Staph aureus
Hemolysis
Beta-hemolytic
Staph aureus
Appearance
bundle of grapes
Staph aureus
Ferments
Mannitol
Staph aureus
Plate on
looks yellow (aur) on blood agar;
turns mannitol yellow on mannitol salt agar
Staph aureus
Virulence factor
Protein A
Binds IgG
Staph Aureus
Diseases
Inflammatory - pneumonia - patchy infiltrates - most commonly a postviral superinfection
Inflammatory - Septic arthritis
nflammatory - Abscesses
Rapid-onset acute endocarditis - IV drug users - tricuspid valve
Osteomyelitis
Scalded skin syndrome - exfoliative toxin (a protease)
TSS - TSST (superantigen –> cytokine storm)
rapid onset food poisoning - vomiting - ingested preformed toxin Impetigo
Staph aureus
Treatment
If methicillin-sensitive, use a penicillin ie Nafcillin
MRSA - altered penicillin-binding proteins –> resistance –> tx with vancomycin
Staph Epidermidis Location
Infects artificial joints and hardware; indwelling catheters; covers skin as normal flora; prosthetic heart valves
Staph Epidermidis
Gram stain
Pos
Staph Epidermidis
Catalase
Pos
Staph Epidermidis
Coaguluase
Neg
Staph Epidermidis
Urease
Pos
Staph Epidermidis
Novobiocin
Sensitive
Staph Epidermidis
Shape and Appearance
Coccus, clusters
Staph Epidermidis
Virulence Factor
Produces copius adhesive biofilms (polysaccharides)
Coating protects it from immune cells
Staph Epidermidis
Diseases
Most common cause of endocarditis of prosthetic valves
Commonly contaminates blood cultures
Staph Epidermidis
Treatment
Vancomycin;
replace infected prosthesis
Staph Saprophyticus
gram stain
Pos
Staph Saprophyticus
Catalase
Pos
Staph Saprophyticus Coagulase
Neg
Staph Saprophyticus Urease
Pos
Staph Saprophyticus Novobiocin
Resistant
Staph Saprophyticus Shape and Appearance
Coccus, clusters
Staph Saprophyticus Diseases
UTIs in sexually active females
Step Pyogenes (Group A) Gram stain
Pos
Step Pyogenes (Group A) Bacitracin
Sensitive
Step Pyogenes (Group A) Hemolysis
Beta-hemolytic
Step Pyogenes (Group A) Shape and Appearance
Coccus, chains
Step Pyogenes (Group A) Virulence Factors
Encapsulated by hyaluronic acid (non-immunogenic) M protein - highly antigenic - in cell wall - 1. Interferes with opsonization and is anti-phagocytic; 2. Very antigenic and elicits strong humoral response - our antibodies created cross-react with myosin (MOLECULAR MIMICRY) Streptolysin O - Lyses RBCs (beta-hemolytic) Streptokinase - Converts plasminogen to plasmin –> lyses clots DNA-ases (DNAase B) - Depolymerize DNA
Step Pyogenes (Group A) Diseases
Impetigo - honeycrusted Pharyngitis Cellulitis and Erysipela Scarlet fever - strawberry tongue, pharyngitis, widespread rash that spares the face - Strep pyogenic exotoxin (SPE) Toxic-shock-like syndrome (superantigen) - SPE (Spe A and C) Necrotizing fasciitis - SPE (SpeB - protease) Rheumtaic fever - Type II hypersensitivity rxn - M protein - mitral valves –> mitral stenosis - occurs after untreated pharyngitis - JONES criteria: J Joints (polyarthritis) O (heart) valvular damage, myocarditis, pericarditis, N Nodules (subcutaneous) E Erythema marginatum S Sydenham’s chorea PSGN - Type III hypersensitivity rxn - circulating antigen-antibody immune complexes - cola-colored urine and facial swelling from edema - 2-3 weeks after initial infection - can occur after pharyngitis or superficial infection ie impetigo
PSGN
PSGN - Type III hypersensitivity rxn - circulating antigen-antibody immune complexes - cola-colored urine and facial swelling from edema - 2-3 weeks after initial infection - can occur after pharyngitis or superficial infection ie impetigo Early tx with penicillin prevents RF but not PSGN
Rheumatic fever
Rheumtaic fever - Type II hypersensitivity rxn - M protein - mitral valves –> mitral stenosis - occurs after untreated pharyngitis - JONES criteria: J Joints (polyarthritis) O (heart) valvular damage, myocarditis, pericarditis, N Nodules (subcutaneous) E Erythema marginatum S Sydenham’s chorea Early tx with penicillin prevents RF but not PSGN
JONES Criteria for rheumatic fever
JONES criteria: J Joints (polyarthritis) O (heart) valvular damage, myocarditis, pericarditis, N Nodules (subcutaneous) E Erythema marginatum S Sydenham’s chorea
ASO titers and Strep A
ASO titers can tell us if a pt has recently had a Strep A infection (ab’s to Streptolysin O)
Strep Agalactiae (Group B) Diseases
1 cause of meningitis in neonates Sepsis in neonates Pneumonia
Strep Agalactiae (Group B) Bacitracin
Bacitracin resistant; CAMP positive
Strep Agalactiae (Group B) Hemolysis
Beta-hemolytic
Strep Agalactiae (Group B) Virulence Factor
polysaccharide capsule
Strep Agalactiae (Group B) Location
Vaginal canal (test at 35wk)
Interstitial opacities on chest x-ray are common in
Atypical pneumonia Legionella species, Mycoplasma pneumoniae, and Chlamydia pneumoniae
Tx atypical pneumonia
macrolides (azithromycin, clarithromycin) or doxycycline. Beta-lactams (penicillins, cephalosporins) are ineffective in the treatment of this condition since the organism lack peptidoglycan.
The Dieterle silver stain is used to identify
Legionella pneumophila Smokers, alcoholics Elderly, immunocomprimised
The Quellung reaction is a technique used to identify the capsular serotype of
Streptococcus pneumoniae
Requirement for cysteine is a characteristic of four genera of bacteria:
Francisella, Legionella, Brucella, and Pasteurella
Requirement for factors X and V is characteristic of:
Haemophilus
acid-fast oocysts 4-6 microns in diameter; AIDS patient
Cryptosporidium The most common causes of diarrhea in AIDS include Microsporidium, Cryptosporidium, Cytomegalovirus, Salmonella, Campylobacter and AIDS enteropathy.
Genetic shift
When viruses from animals and man infect a single cell and accidentally reassort the segments of their genomes, drastic changes in the virus can occur (genetic shift) causing pandemics.
Genetic Drift
Accumulated mutations in the RNA genome cause genetic drift, necessitating yearly revaccination against the current influenza strains.
Phylogeny: Influenza virus
Orthomyxoviridae, 8 segments ss RNA Negative sense
Toxoplasmosis in infants
chorioretinitis, intracranial calcifications, and encephalitis leading to hydrocephalus, possibly resulting in mental retardation, seizures, blindness, deafness, and death.
Hydrops fetalis is a common consequence of fetal infection with:
Parvovirus B19 infects immature erythrocytes
Patent ductus arteriosus and pulmonary stenosis are aspects of
congenital rubella syndrome, caused when rubella virus crosses the placenta.
ring-enhancing lesions in the brain, and in an AIDS patient, this is extremely suggestive of infection with:
Toxoplasma gondii
Most common mode of transmission for toxo
The most common means of transmission of toxoplasmosis in the United States is the ingestion of cysts from undercooked pork.
How can toxo present in AIDS patients?
Toxoplasma necrotizing encephalitis is very common among AIDS patients.
How does Chagas affect the heart?
Cardiac involvement manifests with ventricular dilatation and congestive heart failure secondary to myocyte necrosis and fibrosis. In Chagas disease, any type of atrial or ventricular arrhythmia may occur.
Yersinia pestis Vector
Flea Bubonic plague
Rickettsia prowazekii Vector
Louse Epidemic typhus
Trypanosoma Cruzi
Trypanosoma cruzi is an intracellular protozoan that localizes mainly in the heart and nerve cells of the myenteric plexus, leading to acute myopericarditis as well as chronic fibrosing myocarditis as well as dysmotility of hollow organs, such as the esophagus, colon, and ureter.
Listeriosis Treatment
The treatment of choice is intravenous administration of ampicillin or penicillin, often in combination with an aminoglycoside. Trimethoprim-sulfamethoxazole has been used successfully in patients with penicillin allergy.
Silver stain to diagnose
Silver stain (choice D) is used to diagnose Pneumocystis jiroveciipneumonia. Silver-staining cysts in bronchial alveolar lavage fluids or biopsy is diagnostic for Pneumocystis jirovecii.
Use the Tzanck smear to diagnose
Tzanck smear (choice E) is used to diagnose herpesvirus infections. It involves touching a slide or coverslip to a lesion to lift off the multinucleated giant cells caused by the infection.
Strep toxin in scarlet fever
The fever and rash in this disease are due to the production of pyrogenic exotoxins A-C, which are phage-encoded.
C. perfringens toxin
Lethicinase
Pneumonic plague can manifest with
Pneumonic plague can manifest with chest pain, difficulty breathing, and a productive cough that can be blood-tinged.
Congenital rubella syndrome
Congenital rubella syndrome also consists of patent ductus arteriosus, pulmonary stenosis, microcephaly, cataracts, and deafness.
How to identify entamoeba histolytica
The trophozoite of E. histolytica can be identified by the “cart-wheel” distribution of chromatin in the nucleus and the presence of ingested red blood cells.
How does Trich present?
Trichomonas vaginalis is a sexually transmitted protozoan that causes a frothy, yellow-green, malodorous vaginal discharge. It is a flagellated protozoan and has corkscrew motility on a wet mount.
Pertussis Toxin
Pertussis toxin (A and B component), which ADP ribosylates Gi (thus inhibiting the negative regulator of adenylate cyclase) leading to increased cAMP. Multiple effects are produced by interrupting activities regulated by cAMP. As a result, it causes: Increased insulin production leading to hypoglycemia Lymphocytosis promotion Blockade of immune effector cells Increased histamine sensitivity
Lymphogranuloma venereum:
The primary lesion is usually a self-healing papule or shallow ulcer. Painful, enlarged, abscessed lymph nodes termed “buboes” contain stellate abscesses. The causative organism is Chlamydia trachomatis. In contrast, granuloma inguinale (caused by Klebsiella granulomatis) is characterized by painless ulcers.
Phylogeny Parvovirus B19
Naked Smallest DNA virus ssDNA
Parvovirus B19 Mode of transmission
Respiratory droplets; Vertical transmission (TORCH)
Parvovirus B19 Diseases
Slapped cheek disease aka Fifth disease aka Erythema Infectiosum Fever –> rash on face –> lacey rash spreads down body Adults: joint pain, transient aplastic anemia (SCD)
Parvovirus B19 can cause what in SCD patients?
Aplastic anemia - adipocytes in bone marrow have a cobweb look
Mothers who contract Parvovirus B19 during the first or second trimesters of pregnancy fear what complication?
Hydrops fetalis
Phylogeny CMV
DNA replicate inside nucleus Herpesvirus family (CMV remains latent in B and T cells and macrophages)
What is the most common fetal viral infection?
CMV - mostly asymptomatic; biggest cause of mental retardation and sensorineural hearing loss in children blueberry muffin rash, hepatosplenomegaly, jaundice intracranial calcifications (like toxo) –> seizures ventriculomegaly hearing loss
Which trimester of pregnancy is associated with the highest risks of congenital CMV?
Second hydrops fetalis possible
CMV tx
Ganciclovir, Foscarnet when UL97 gene mutation
How does CMV present in immunocompetent?
Mono But Monospot is negative
Phylogeny Poxvirus
Largest knownn DNA virus Makes own envelope replicates completely in the cytoplasm; has a special DNA-dependent RNA polymerase
What kind of inclusions dows Poxvirus form?
Guarnieri inclusion bodies - sites of replication in the cytoplasm
What shape is associated with poxvirus?
Dumbbell shaped core
How to tell the lesions in smallpox apart from the lesions in chicken pox
Chicken pox lesions all of different ages; Small pox lesions all the same age
Molloscum contagiosum is caused by:
Poxvirus
Diffuse molloscum contagiosum infection in adults suggests
HIV infection
Phylogeny Papillomavirus
dsDNA naked
High yield Papillomaviruses
1-4 - verruca vulgaris - cutaneous common wart; 6, 11 - laryngeal papillomatosis, a recurrent respiratory papillomatosis (children), vertical (at birth) - anogenital warts, “condyloma acuminata” 16, 18, 31, 33 - anogenital squamous cell carcinomas
Condyloma LATA
Syphilis
HPV vaccine covers
6, 11, 16, 18 inactivated subunit vaccine
Most common STD
HPV
HPV E6 and E7
proteolysis tumor suppressors and growth checkpoints by Rb (E7) and p53 (E6)
If post-coital bleeding, think
Cervical cancer Invasive cervical/penile cancer is an AIDS defining illness
Phylogeny Treponema Pallidum
Spirochete
What is needed for direct vizualization of Treponema Pallidum?
Darkfield microscopy Use VDRL or RPR screening tools, use FTA-ABS specifically for treponema
Maculopapular rash occurs on palms and soles weeks to months after infection - organism?
Treponema pallidum - Secondary syphilis along with condyloma lata on mucous membranes
Aortitis of ascending thoracic aorta –> “tree barking” appearance
Part of tertiary syphilis Destroys vasa vasorum - aneurism formation Along with tabes dorsalis, gummas, Argyll-Robertson pupil
Tabes dorsalis involves what part of the spinal cord?
Posterior
Saber shins - anterior bowing of tibia; saddle nose; Notched incisors and molars with enamel outgrowths; Deafness
Congenital syphilis
Jarisch-Herxheimer Reaction
Dying spirochetes releasing stuff activating cytokines fever and chills
Phylogeny Leptospira
Spirochete Hawaii excreted in urine of animals
Flu-like symptoms, fever, conjunctival suffusion, no exudate, renal dysfx jaundice from liver damage
WEILS disease - leptospirosis seeds many organs
Borrelia burgdorferi Geographic distribution
Northeastern US
Borrelia burgdorferi Vector
Ixodes scapularis - transmits Lyme, Babesiosis and Erlichiosis
How to visualize Borellia
Giemsa stain Wright’s stain
Stage 2 Lyme disease
bilateral facial nerve palsy myocarditis –> heart block
Stage 3 Lyme disease
arthritis of large joints - migratory polyarthritis; memory difficulty, or lymphocytic meningitis
Treat severe or later presentations of Lymes with
Ceftriaxone
Rickettsia use eukarytic host:
NAD+ and CoA for replication
Phylogeny All Rickettsiae
weakly gram negative coccobacillary obligate intracellular
Use Weil-Felix agglutination test to identify:
Rickettsia
Ricketssia Prowazekii rash
Starts on trunk and spreads outwards; Spares hands, feet, and head
Ricketssia Prowazekii Population
POW Military recruits Louse poops on skin, we scratch
Ricketssia Prowazekii Disease
Epidemic typhus rampant outbreak arthralgia, myalgia, pneumonia, rash, encephalitis, coma
Rickettsia Rickettsii How to visualize
Giemsa stain
Rickettsia Rickettsii Transmission
Dermacentor tick - direct biting
Rickettsia Rickettsii Rash
incubation period 2-14 days; Extremeties, working to trunk
Rickettsia Rickettsii Disease
RMSF Rash, headache, fever, myalgias
Phylogeny Neisseria gonorrheae
gram-negative, oxidase-positive diplococcus.
Chlamydia trachomatis Phylogeny
non-Gram staining intracellular pathogen
Neisseria gonorrheae Treatment
Treat Neisseria gonorrhoeae with dual therapy of ceftriaxone plus azithromycin.
Treatment Tularemia
Streptomycin
Phylogeny Francisella tularensis
a gram-negative coccobacillus facultative intracellular –> can spread in body
Mode of transmission Francisella tularensis
Tick Direct handling of rabbits Can be aerosolized
Francisella tularensis Disease
Painful ulcer at infection site –> macrophages –> lymph nodes –> caseating necrosis; regional lymphadenopathy
Brucella Reservoir
Farm animals
Brucella At risk populations
Veterinarians, ranchers, farmers, recent consumption of milk or cheese products
Phylogeny Brucella
Facultative intracellular –> macrophages –> can travel throughout the reticuloendothelial system gram negative
Brucellosis symptoms
fever, chills, anorexia undulating fever hepatosplenomegaly osteomylelitis (chronic)
Brucellosis Treatment
Doxycycline and rifampin adjunctive therapy
Pneumocystis jirovecii Transmission
Respiratory droplets
Pneumocystis jirovecii Infection in immunocompetent
Asymptomatic
Pneumocystis jirovecii What kind of pneumonia
Diffuse, interstitial pneumonia Ground glass appearance in both lungs NO productive cough
Pneumocystis jirovecii Diagnosis
Bronchoalveolar lavage –> methamine silver stain Oval shaped
Phylogeny Herpes simplex 2
Double-stranded DNA, enveloped with nuclear membrane, icosahedral
The coagulase test is used to differentiate
The coagulase test (choice B) is used to differentiate Staphylococcus aureus from the other staphylococcus species. Staphylococcus aureus is coagulase-positive; the others are coagulase-negative.
Strep pneumo and Strep viridans Hemolysis
Alpha-hemolytic (green hue)
Optochin Strep pneumo
Optochin sensitive
Phylogeny and shape Strep pneumo
Lancet shaped diplococci Gram positive Bile soluble Capsule
Strep pneumo Disease
Lobar pneumonia Lower lobes Rust-colored sputum MOPS - Meningitis, Otitis Media, Pneumonia, Sinusitis
Strep pneumo Virulence factor
Protease that cleaves IgA –> mucosal invasion
Strep pneumo At risk population
SCD pts
Strep pneumo Treatment
Ceftriaxone, Macrolides
Strep pneumo Vaccine
for adults - 23 valent, only IgM response; for kids - 7 valent, IgG response
When is spore formation most occurring?
In the growth curve of bacteria, toxins build up in the stationary phase The stationary phase will be the time of maximal spore production
Phylogeny RSV
RSV is a paramyxovirus with negative single-stranded RNA, helical shape, and an envelope.
Mode of transmission Paramyxoviruses - RSV and measles
Respiratory droplets
Measles Symptoms
Rubeola Paramyxovirus 4 Cs: Cough, coryza (runny nose), conjunctivitis, Koplik spots; fever then, maculopapular rash starting on ears, neck then rest of body, itchy, then rash becomes confluent then SSPE 5-15 years later
Measles Virulence Factors
HA - RBCs stick together in test tubes Fusion protein - formation of syncitia (multinucleated giant cells)
Use what vitamin to reduce morbidity in measles?
Vitamin A
Parotitis, Orchitis
Mumps Paramyxovirus Complication - meningitis
Mumps Virulence factors
HA - RBCs stick together in test tubes Fusion protein - formation of syncitia (multinucleated giant cells) NA
Pathogenesis RSV
RSV Paramyxovirus Attached to G protein in respiratory endothelium Pneumonia, Bronchiolitis Fusion protein
Treatment RSV
Ribavirin don’t use in pregnant women and children Use Palivizumab for kid prophylaxis
Croup
Paramyxovirus aka Laryngotracheobronchitis
Croup Virulence factors
HA - RBCs stick together in test tubes Fusion protein - formation of syncitia (multinucleated giant cells) NA
Chickenpox Complications
Chickenpox may be complicated by secondary bacterial infection, pneumonia, systemic spread (immunosuppressed patients), neurologic involvement (rare), Reye syndrome (rare), and/or hemolytic anemia (rare)
Bacteria that commonly produce pneumonia that develops in the context of influenza include:
S. aureus, Haemophilus influenzae, and Streptococcus pneumoniae. Of these, S. aureus is the most destructive to lung tissue and likely to cause cavitary lesions. S. aureus is a gram-positive, catalase-positive, coagulase-positive coccus.
Treatment of symptomatic neurocysticercosis
Treatment of symptomatic neurocysticercosis involves the use of albendazole, praziquantel, or both with or without corticosteroids.
Mode of transmission Cystercercosis
Cysticercosis is a parasitic infection caused by the larval cysts of the tapeworm Taenia solium. Patients acquire the infection by ingesting the eggs, either through ingestion of human feces-contaminated water or food or by autoinfection of a person infected with the adult worm who transmits the eggs from the perianal area to the mouth via contaminated fingers.
Bartonella henslae
In the immunocompromised patient, it can cause bacillary angiomatosis, which is the vascular proliferative form of infection and can affect any organ system, although it most commonly affects the skin and subcutaneous tissue.
Bartonella henslae Phylogeny
Gram negative Zoonotic
Bartonella henslae Special stain
Warthin-Starry stain (a silver stain)
Bartonella henslae Diseases
Cat scratch disease - fever, regional (axillary) lymph nodes) Bacillary angiomatosis - immunocomprimised - vascular lesions in addition to the above
Bartonella henslae Treatment
Doxycycline in immunocomprimised Azithromycin in cat scratch disease if severe, otherwise, self-limiting
Neisseria gonorrhoeae Virulence Factor
Pili mediate attachment, protection from phagocytosis, antigenic variation, and adherence.
Legionella Culture
Facultative intracellular pathogen; requires cysteine and iron in media (provided in buffered charcoal yeast extract [CYE]). This medium also contains antimicrobial drugs including colistin and vancomycin to inhibit the growth of other Gram-negative and Gram-positive bacteria, respectively.
Diagnosis SSPE
EEG (periodic activity), marked elevation of immunoglobulins in CSF, and alteration of the white matter of both hemispheres and the brain stem. Symptoms develop gradually and consist of behavioral changes, myoclonus, ataxia, ocular abnormalities, spasticity, and coma.
Immunosuppressed patients with owl’s-eye inclusion bodies in cells in urine sediment:
CMV
Painful, soft ulcer on the genitals:
Haemophilus ducreyi.
Haemophilus ducreyi Phylogeny
a pleomorphic, gram-negative rod that displays a characteristic pattern (“school of fish”) on Gram-stained slides.
Haemophilus ducreyi Plate on
It grows on chocolate agar or on whole blood agar with a satellite phenomenon (around Staphylococcus aureus).
Site specific recombination
Site-specific recombination is the integration of one DNA molecule into another DNA molecule with which it has no homology except for a small site on each DNA.
Acute HBV infection is characterized by
a positive serology for HBsAg, HBeAg, and anti-HBc-IgM antibody, but absence of HBsAb and HBeAb.
Diseases that can cause reactive arthritis
Shigella, Salmonella, Yersinia, Campylobacter, Chlamydia
Catalase
Abscesses are commonly produced by catalase-positive organisms. Catalase is an enzyme that converts hydrogen peroxide into water and oxygen. Hydrogen peroxide is one of the toxic oxygen compounds generated by the action of NADPH oxidase in phagocytes and it acts as the substrate for myeloperoxidase. Producing catalase, therefore, allows bacteria to survive longer intracellularly. Catalase-positive organisms include the staphylococci, Pseudomonas, Candida, Aspergillus, and the Enterobacteriaceae.
Viruses with segmented genome:
ROBA (Reoviridae, Orthomyxoviridae, Bunyaviridae, Arenaviridae)
HSV-1 Phylogeny
Herpesviridae: double-stranded icosahedral DNA viruses with nuclear membrane envelope
H. Pylori Pathogenesis
Urease production raises the pH of the stomach and allows invasion of the stomach lining
Clostridium perfringens Hemolysis
Double zone of hemolysis on blood agar
Clostridium perfringens Phylogeny
Obligate anaerobe gram pos
Clostridium perfringens Treatment
IV Pen G
Clostridium perfringens Toxin
Alpha toxin works on cell membrane (RBC –> hemolysis)
Clostridium perfringens Food Poisoning
Late onset
Actinomyces israelii Phylogeny
Branching (filamentous) rod Gram pos Obligate anaerobe Normal flora of the oral cavity
Nocardia Phylogeny
Obligate aerobe Gram pos Filamentous rod
Actinomyces israelii Disease
Cervicofacial actinomyces infection draining sulfur sinus tracts
Actinomyces israelii
Pen G
Legionella Phylogeny
Use silver stain, but technically gram neg Oxidase pos
Legionella Plate on
Buffered charcoal yeast extract with cysteine and iron added
Legionella Diseases
Pontiac fever Legionnaires disease - smokers, atypical pneumonia - patchy infiltrate w/ consolidation of 1 lobe, neurologic symptoms, diarrhea, HIGH fever *hyponatremia*
Legionella Diagnose
Urine antigen test sputum culture
Legionella Treatment
Macrolides, fluoroquinolones better
Histoplasma capsulatum Location
Midwest and southish cave, farm
Histoplasma capsulatum Transmission
Inhalation
Histoplasma capsulatum Diagosis`
KOH prep culture rapid serum/urine antigen test- ovoid bodies are macrophages filled with histoplasma
Histoplasma capsulatum Size
Smaller than RBC
Histoplasma capsulatum Dimorphic
Mold in the cold Yeast in the heat
Histoplasma capsulatum Diseases
Pneumonia - granulomas - cavitary lesions and calcified lesions with fibrotic scarring Can be asymptomatic Erythema nodosum
Histoplasma capsulatum In Immunocomprimised
Dissemination to liver and spleen - calcifications Skin and neuro findings
Histoplasma capsulatum Treatment
Mild - Azole - Fluconazole, Ketoconazole Severe - Amphotericin B
Blastomyces Dermatitidis Location
Great Lakes, Ohio River Valley, some souther US
Blastomyces Dermatitidis Treatment
Mild - Azole - Fluconazole, Ketoconazole Severe - Amphotericin B
Blastomyces Dermatitidis Diseases
Hazy lung CXR - patchy alveolar infiltrate Can be acute or chronic Asymptomatic possible
Blastomyces Dermatitidis Dimorphic
Yes
Blastomyces Dermatitidis Transmission
Inhalation of spores
Blastomyces Dermatitidis Appearance
Broad based budding
Blastomyces Dermatitidis Size
Same size as RBC
Blastomyces Dermatitidis Immunocomprimised
Osteomyelitis Skin problems
Blastomyces Dermatitidis Diagnosis
KOH prep Culture Urine antigen test
Coccidiodes Immitis Location
California and southwestern US
Coccidiodes Immitis Treatment
Mild - Azole - Fluconazole, Ketoconazole Severe - Amphotericin B
Coccidiodes Immitis Diseases
“San Jaquin Valley fever” Asymptomatic Self limited acute pneumonia Some cavities or conodules on CXR (not always) Erythema nodosum = robust immune response = only seen in healthy people
Coccidiodes Immitis Size
larger than RBC
Coccidiodes Immitis Transmission
Inhalation of spores in dust; Earthquakes are risk factors
Coccidiodes Immitis Dimorphism
Mold in cold Spherules of endospores in heat
Coccidiodes Immitis Immunocomprimised
Skin Osteomyelitis Meningitis
Coccidiodes Immitis Diagnosis
KOH prep Culture Serology for ab titers (as with all fungi)
Paracoccidiodes Brasilliensis Location
Brazil, South America
Paracoccidiodes Brasilliensis Size and Appearance
Captains wheel Much bigger than RBC
Paracoccidiodes Brasilliensis Treatment
Mild - Azole - Fluconazole, Ketoconazole Severe - Amphotericin B
Paracoccidiodes Brasilliensis Diseases
Cervical lymphadenopathy –> lungs, granulomas, mucosal ulcers in mouth
Paracoccidiodes Brasilliensis Dimorphic
Yes
Paracoccidiodes Brasilliensis Transmission
Respiratory droplets
Malassezia furfur Disease
Pityriases versicolor - dermatologic annoyance (not itchy) - lipid degradation destroys melanocytes - stays in stratum corneum
Malassezia furfur Appearance
Spaghetti and meatballs on KOH prep
Malassezia furfur Location
hot and humid conditions
Malassezia furfur Immunocomprimised
Neonates and TPN
Malassezia furfur Treatment
Selenium sulfate
Naegleria fowleri
Naegleria fowleri is a free-living amoeba found in warm, freshwater lakes. Diving into such lakes causes changes in pressure that can force the organism through the cribriform plate and result in the production of necrotic lesions spreading from the olfactory lobes. The tissue form of the organism is a flagellated trophozoite.
Lipid A
Gram-negative septic shock is caused by endotoxin (lipopolysaccharide, LPS) in the outer membrane of gram-negative organisms. Lipid A is the toxic component of LPS. Endotoxin acts by direct stimulation of macrophages to secrete large amounts of IL-1, IL-6 and TNF-alpha, which will then cause excessive vasodilation and ultimately, shock.
Generalized transduction
The mechanism involving transfer of bacterial DNA from cell to cell using a lytic phage as a vector is called generalized transduction.
Conjugation
Conjugation is one of the three methods whereby DNA is transferred from one cell to another. In this process, there is a gene transfer from donor (F+ or Hfr cell) to recipient (F– cell) during cell-to-cell contact. The sex pili (genes on F factor) play a role in establishing cell-to-cell contact. Then a single strand (or a portion thereof) of the double helix of DNA is transferred from the donor (or male) cell to the recipient or female cell. Chromosomal genes transferred in by conjugation have to be stabilized by homologous recombination (in an Hfr X F– cross).
Cause of malignant otitis externa
Pseudomonas aeruginosa causes malignant otitis externa, which is a severe necrotizing infection of the external ear canal. Infection tends to spread to the mastoid bone, temporal bone, sigmoid sinus, base of the skull, meninges, and brain. Patients at increased risk include the elderly, people with diabetes, and the immunocompromised.
Ecthyma gangrenosum
Ecthyma gangrenosum is a black, necrotic skin lesion that is seen in septicemic patients. Pseudomonas aeruginosa
On biopsy, the characteristic appearance is crescent-shaped protozoa adjacent to the brush border. Organism?
Giardia
PJP How to visualize
The sample is then submitted to the direct fluorescent antibody test or stained with Gomori methenamine silver stain to visualize the organisms.
How does Protein A (staph aureus) work?
Protein A inhibits opsonization by binding to the Fc component of IgG
Syphilis Diagnosis
During secondary syphilis, VDRL is the best test to order for this patient. It must then be confirmed by the FTA-ABS. During primary syphilis, biopsy of a chancre is examined with darkfield microscopy. During tertiary syphilis, a specific treponemal serologic test such as the FTA-ABS or microhemagglutination test is necessary because the VDRL will frequently revert to negative in this phase.
Poxvirus
All DNA viruses are icosahedral, except for Poxviruses, which are described as brick-shaped complexes. Poxvirus DNA is enveloped. All DNA viruses replicate their DNA in the nucleus, except for Poxvirus, which replicates in the cytoplasm via a virion-associated transcriptase.
Ascaris lumbricoides
Ascaris lumbricoides infection, the only helminth infection caused by a cylindrical white worm of this remarkably large size. It is acquired directly, with no intermediate host, from fecal contamination from other human beings, and the stage of the life cycle that is transmitted is the egg. The eggs hatch into larvae in the intestine. The larvae penetrate the intestinal wall and migrate to the lungs, at which time they can cause pulmonary symptoms. The larvae are then swallowed, and mature and mate in the gastrointestinal tract, where they lay eggs that can be passed on to another person. Most infections are asymptomatic, but early infection may be marked by respiratory symptoms (cough, dyspnea, wheezing) and fever. In later stages, gastrointestinal symptoms are often prominent,
short, germinating hyphae on the germ-tube test.
Candida albicans
Hyphae with rosettes of microconidia
the environmental form for Sporothrix schenckii. This fungus causes rose-gardener’s disease, which is a cutaneous mycetoma associated with traumatic implantation while gardening.
bacteria that are capable of natural transformation include:
Haemophilus influenzae, Streptococcus pneumoniae species, and Neisseria species.
progressive multifocal leukoencephalopathy (PML)
progressive multifocal leukoencephalopathy (PML), which is a rapidly progressive demyelinating disorder in which the JC virus (a polyomavirus) infects oligodendroglial cells in the brain. The eosinophilic inclusions represent accumulations of JC virus. PML occurs in about 1% of AIDS patients, and is the AIDS-defining illness in half of the patients who develop the condition. Symptoms include aphasia, hemiparesis, cortical blindness, ataxia, and conjugate gaze abnormalities. The condition can progress to quadriparesis and coma. There is no effective treatment for this disorder. JC virus is ubiquitous and seropositivity reaches about 70% by adulthood. Thus, reactivation is seen with immunosuppressed hosts. JC infections are usually asymptomatic in immunocompetent individuals.
Toxo treatment
sulfadiazine and pyrimethamine
The most common bacterial pathogens of conjunctivitis include
Haemophilus influenzae, Staphylococcus aureus, Streptococcus pneumoniae, and Moraxella spp.
Haemophilus influenzae Plate on
Haemophilus influenzae requires factors X and V: growth on chocolate agar
Hepatitis E infection in _________ has a high mortality.
pregnant women
Hep E virus
single-stranded, positive-sense RNA.
All RNA positive viruses replicate in the:
Cytoplasm
There is an important association between colon cancer and endocarditis due to
Streptococcus bovis. S. bovis is a group D Streptococcus whose cell wall has glycerol teichoic acid.
Corneybacterium diptheriae Plate on
Tellurite and Loeffler’s media
Corneybacterium diptheriae Plate on
Tellurite and Loeffler’s media; Elek’s test to see if the strain is toxic
Adenovirus #1 cause of
tonsillitis
Adenovirus phylogeny
DNA naked
Adenovirus transmission
respiratory droplets; fecal-oral
Adenovirus transmission
respiratory droplets; fecal-oral
Adenovirus Population
Close quarters public pools kids
Adenovirus Diseases
hemorrhagic cystitis tonsillitis conjunctivitis
Window period
During the “window period” of hepatitis B infection, neither hepatitis B surface antigen (HBsAg) nor its antibody (HBsAb) can be detected in the serum of the patient. This is due to precipitation of antigen-antibody complexes in their zones of equivalence and, thereby, their removal from the circulation. Serologic tests conducted during the window period will be positive for HBcAb and HBeAb.
Symptoms and cause of infective endocarditis
acute infective endocarditis secondary to intravenous drug use, as evidenced by the bruising in the right antecubital fossa. Peripheral cutaneous or mucocutaneous lesions of infective endocarditis include petechiae, splinter hemorrhages, Janeway lesions, Osler’s nodes, and Roth spots. Patients with infective endocarditis can also have septic embolic, including pulmonary embolic, which would show up as patchy infiltrates in both lungs. The most common cause of acute bacterial endocarditis is Staphylococcus aureus.
Trypanosoma Brucei
Disease
African sleeping sickness - Coma
Parasite: lymphadenopathy, recurrent fevers
Trypanosoma Brucei
Vector
Tse Tse Fly
Trypanosoma Brucei
Location
West and South Africa
Trypanosoma Brucei
Diagnosis
Trypomastigotes seen on blood smear
Trypanosoma Brucei
Description
Variable surface glycoproteins undergoing constant antigenic variation, enabling chronic infection
Motile, single flagella
Trypanosoma Brucei
Treatment
Suramin for peripheral blood infection
Melarsoprol for CNS infection - highly toxic side effect profile
Naegleria Fowleri
Location
Lakes, freshwater, standing water
Naegleria Fowleri
Diseases
Rapidly fatal meningioencephalitis
Trophozoite enters CNS through cribiform plate
Naegleria Fowleri
Diagnosis
Lumbar puncture
Naegleria Fowleri
Treatment
Amphotericin B
Babesiosis
Symptoms
Hemolytic anemia
Hemoglobinuria
Jaundice
Irregularly cycling Fevers
*most are asymptomatic
Babesia
Vector
Ixodes tick
Babesia
At risk population
SCD patients
HIgher risk of severe disease
Babesia
Diagnosis
Thick blood smear;
Maltese cross appearance in RBCs made of trophozoites
Babesia
Location
Northeastern US
Babesia
Treatment
Atovaquone;
Azithromycin
Leishmania donovani
Location
Mediterranean, Middle East, Africa
Leishmania braziliensis
Host
Humans, other vertebrates
sandFly - vector
Leishmania braziliensis
Disease
Cutaneous leishmaniasis
ulcers
Leishmania braziliensis
Diagnosis
Amastigote is intracellular form seen within macrophages;
Requires aspirates from lymph node, spleen, skin lesions
Leishmania donovani
Disease
Visceral leishmaniasis aka black fever aka kala-azar
Fatal if untreated
Pancytopenia
Hepatosplenopegaly, fever, weakness
Leishmaniasis
Treatment
Stibogluconate for cutaneous
Ampho B for visceral
