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Microbiology Flashcards

1
Q

Difference between Gram+ and Gram- bacterial structure.

A

Gram+:
Produce spores
Cell wall (peptidoglycan) layer much thicker
Lipoteichoic acid in cytoplasmic membrane - induce TNF/IL-1

Gram-:
Outer membrane with endotoxin, OMP, and porins - induce TNF/IL-1
Periplasm containing B-lactamase

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2
Q

Bacteria that do not gram stain.

“These Microbes May Lack Real Color”

A

Treponema
Mycobacteria (high lipid content in cell wall)
Mycoplasma (no cell wall)
Legionella, Rickettsia, Chlamydia (intracellular)

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3
Q

Stain for acid-fast bacteria - Carbolfuchsin positive organisms red because of Mycolic acid (waxy, long-chain fatty acid) in cell wall

A

Ziehl-Neelsen stain

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4
Q

Medium containing Vancomycin (gram+), Trimethoprim (gram-), and Nystatin (fungi).

A

THAYER-MARTIN AGAR

Neisseria (gonorrhoeae, meningitidis)

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5
Q

Medium producing pink fermenting (acid producing) colonies.

A

MACCONKEY AGAR

Lactose-fermenting enterics:
("mcconKEE'S agar")
Klebsiella
E. Coli
Enterobacter
Serratia

Note - Non-lactose fermenters appear white

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6
Q

Medium for fungi growth.

A

Sabourad agar

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7
Q

Common aerobic bacteria.

(“Nagging Pests Must Breathe”)

Note - Culture on reducing media

A

Nocardia
Pseudomonas
MycoBacterium

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8
Q

Common anaerobic bacteria.

“Can’t Breathe Fresh Air”

A

Clostridium
Bacteroides
Fusobacterium
Actinomyces

Normal in GI tract, pathogenic elsewhere

Lack of catalase/superoxide dismutase makes them susceptible to oxidative damage. Resistant to aminoglycosides which require O2 to enter bacterial cell

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9
Q

Obligate intracellular bacteria.

“Really Close Cousins”

A

Rickettsia
Chlamydia
Coxiella

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10
Q

Facultative intracellular bacteria.

“Some Nasty Bugs May Live FacultativeLY”

A 
Salmonella
Neisseria
Brucella
Mycobacterium
Listeria
Francisella
Legionella
Yersinia pestis
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11
Q

Encapsulated bacteria - antiphagocytic virulence requires opsonization and thus are more pathogenic in asplenic patients.

(“Please SHiNE my SKiS”)

A 
Pseudomonas
S. pneumo
HIB
N. meningitidis
E. coli
Salmonella
Klebsiella
gbS
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12
Q

Urease positive organisms - potentiate struvite stones and raise pH of urine.

(“Pee CHuNKSS”)

A 
Proteus
Cryptococcus
H. Pylori
Nocardia
Klebsiella
S. epidermidis
S. saprophyticus
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13
Q

Catalase positive organisms - common infections in patients with chronic granulomatous disease (NADPH oxidase deficiency).

(“New LiBrary SPACES”)

A 
Nocardia
Listeria
Burkholderia cepacia
Staphylococcus
Pseudomonas
Aspergillus
Candida
Enterobacteriaceae (E. coli, Serratia)
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14
Q

Biofilm producing bacteria.

“SErious Vall Producing Hombres”

A

S. epidermidis
Viridans strep (S. mutans, S. sanguinis)
Pseudomonas
HIB

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15
Q

Bacteria producing IgA protease

A

S. pneumo
HIB
Neisseria

Note - Facilitates bacterial adherence to mucosal surface

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16
Q

Bacteria producing TIII secretion system - direct delivery of toxins from certain Gram- bacteria.

A

Pseudomonas
Salmonella
Shigella
E. coli

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17
Q

Methods of chromosomal gene transfer between bacteria.

A

Hfr x F- conjugation (Hfr means F+ plasmid incorporated into host chromosome)

Transposition to plasmid

Transduction (generalized via lytic or specialized via lysogenic)

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18
Q

Bacterial toxins encoded in a lysogenic phase.

“ABCD’S”

A 
group A strep erythrogenic toxin
Botulinum toxin
Cholera toxin
Diphtheria toxin
Shiga toxin
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19
Q

Mechanism of endotoxin induced sepsis (gram- rods) or meningococcemia (gram- cocci; i.e. Neisseria).

Composed of O-antigen, core polysaccharide, and lipid A (toxic) which is released by cell lysis or membrane blebs - heat stable.

A 
Macrophage activation (TLR4):
IL-1/6 = fever
TNF-a = fever, hypotension
Nitric oxide = hypotension

Complement activation:
C3a = histamine (hypotension, edema)
C5a = neutrophil chemotaxis

Tissue factor activation:
Coagulation cascade = DIC

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20
Q

Gram+ lab algorithm.

A

Bacilli:
Aerobic = Listeria, Bacillus, Corynebacterium
Anaerobic = Clostridium

Branching filaments:
Aerobic = Nocardia
Anaerobic = Actinomyces

Cocci (Aerobic):
Catalase test

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21
Q

Gram+ cocci lab algorithm.

A

Catalase- = Streptococcus

Catalase+ = Staphyloccoccus

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22
Q

Gram+ cocci, Catalase+ lab algorithm.

A

Coagulase+ = S. aureus (also b-hemolytic)

Coagulase-, Novobiocin sensitive = S. epidermidis
Coagulase-, Novobiocin resistant = S. saprophyticus

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23
Q

Gram+ cocci, Catalase- lab algorithm.

A

a-hemolysis (partial, green):
Optochin sensitive/bile soluble = S. pneumoniae
Optochin resistant/bole insoluble = Viridans (S. mutans)

b-hemolysis (complete, clear):
Bacitracin sensitive = GAS pyogenes
Bacitracin resistant = GBS agalactiae

y-hemolysis (none, grows in bile):
Growth in NaCl = Enterococcus (E. faecalis)
No growth in NaCl = Nonenterococcus (S. bovis)

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24
Q 
Gram+ cocci in clusters
Catalase+
Coagulase+
b-hemolytic
Golden-yellow pigment
Mannitol fermentation
A

STAPHYLOCOCCUS AUREUS

Causes cellulitis, abscesses, pneumonia following influenza, endocarditis, septic arthritis, and osteomyelitis - Fibrin clot gives predilection for abscesses

Protein A - Binds Fc-IgG inhibiting complement activation and phagocytosis

Produces TSST-1, Exfoliative toxin, Enterotoxin

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25
Q

Fever
Vomiting
Desquamating rash
Septic shock

Elevated AST and ALT
Elevated bilirubin

A

TOXIC SHOCK SYNDROME

TSST-1 superantigen binds MHCII on APCs and T-cell receptor leading to polyclonal CD4+ T-cell activation and cytokine release

Associated with prolonged use of vaginal/nasal packing (S. aureus), or painful skin infections (S. pyogenes).

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26
Q

Nonbloody diarrhea and emesis 2-6 hrs after eating meat, mayonnaise, or custard.

A

S. AUREUS FOOD POISONING

Pre-formed, heat stable, enterotoxin.

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27
Q 
Child with...
Widespread painful erythroderma
Sparing of mucous membranes
Fluid filled blisters
Nikolsky sign
A

S. AUREUS SCALDED SKIN SYNDROME

Exfoliative toxin cleaves Desmoglein-1 (Desmosomes) in epidermis.

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28
Q 
Gram+ cocci in clusters
Catalase+
Coagulase-
Novobiocin sensitive
Urease+
Biofilm producing
Skin flora
A

STAPHYLOCOCCUS EPIDERMIDIS

Infects prosthetics and IV catheters.

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29
Q 
Gram+ cocci in clusters
Catalase+
Coagulase-
Novobiocin resistant
Urease+
Colonizes female genital tract and perineum
A

STAPHYLOCOCCUS SAPROPHYTICUS

2nd most common cause of uncomplicated UTI in young women (1st is e. coli).

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30
Q 
Gram+ lancet diplococci
Catalase-
a-hemolytic
Optochin sensitive
Encapsulated
A

STREPTOCOCCUS PNEUMONIAE

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31
Q

S. pneumoniae is the most common cause of the following 4 diseases.

A 
Pneumonia with rusty colored sputum
Sinusitis
Otitis media
Meningitis (most common in adults)
Sepsis in patients with SCD or asplenia
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32
Q 
Gram+ cocci
Catalase-
a-hemolytic
Optochin resistant ("not afraid op-to-chin")
Biofilm producing
Synthesize Dextrans
A

VIRIDANS STREPTOCOCCI

Dental caries (S. mutans, S. mitis)
Brain abscesses
Endocarditis at damaged heart valves - dextrans bind fibrin clots (S. sanguinis)
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33
Q 
Gram+ cocci
Catalase-
b-hemolytic
Bacitracin sensitive
PYR+
A

GROUP A STREPTOCOCCI/GAS (S. PYOGENES)

Causes pharyngitis, cellulitis, impetigo, and erysipelas.

Pharyngitis may result in rheumatic fever or glomerulonephritis, while Impetigo only results in glomerulonephritis (self-limiting).

Produces…
Exotoxin A
Streptolysin O (RBC lysis, ASO titers)
M protein (binds protein H to prevent opsonization)

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34
Q 
Fever
Circumoral pallor
Strawberry tongue
Sore throat
Blanching, sandpaper-like rash
A

SCARLET FEVER

S. pyogenes Exotoxin A superantigen binds MHCII on APCs and T-cell receptor leading to polyclonal CD4+ T-cell activation and cytokine release

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35
Q 
Intense pain out of proportion to rash
Edema
Discoloration
Crepitus
Dishwater like discharge
A

NECROTIZING FASCIITIS

S. pyogenes Exotoxin A superantigen binds MHCII on APCs and T-cell receptor leading to polyclonal CD4+ T-cell activation and cytokine release

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36
Q

Major criteria for acute rheumatic fever

Note - Antibodies to S. pyogenes M protein enhance host defence but give rise to rheumatic fever (type II hypersensitivity)

A

J<3NES

With positive ASO…

Joints (polyarthritis)
<3 (endocarditis/MR, myocarditis, pericarditis)
Nodules (subcutaneous)
Erythema marginatum
Sydenham chorea

Minor criteria include fever and elevated ESR

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37
Q 
Gram+ cocci in chains
Catalase-
b-hemolysis
Bacitracin resistant
PYR-
cAMP+
Colonizes vagina
A

GROUP B STREPTOCOCCI/GBS (S. AGALACTIAE)

Causes pneumonia, meningitis, and sepsis in babies.

Produces CAMP factor which enlarges area of hemolysis formed by S. aureus.

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38
Q 
Gram+ cocci
Catalase-
y-hemolysis
No growth in NaCl
Colonizes gut
A

NONENTEROCOCCUS (S. BOVIS)

S. bovis type I (S. gallolyticus) causes bacteremia and subacute endocarditis.

Associated with colon cancer.

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39
Q 
Gram+ cocci
Catalase-
y-hemolysis
Growth in NaCl
Colonize colon
A

ENTEROCOCCUS (E. FAECALIS)

Causes UTI, subacute IE, and wound infections - Following GI/GU procedures

All Penicillin G resistant - Some Vancomycin resistant (VRE)

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40
Q

Gram+ rod
Spore-forming (heat resistant)
Polypeptide D-glutamate (not polysaccharide) capsule

A

BACILLUS ANTHRACIS

Produces Anthrax (Edema) toxin...
Edema factor increases cAMP
Lethal factor (zinc-dependent protease) prevents protein kinase signaling
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41
Q

Painless papule surrounded by vesicles - Leads to a painless necrotic ulcer with black eschar.

Associated with livestock

A

CUTANEOUS ANTHRAX

Edema toxin mimics adenylate cyclase increasing cAMP.

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42
Q

Flu-like symptoms

Rapidly progressing to...
Fever
Pulmonary hemorrhage
Mediastinitis
Shock
A

PULMONARY ANTHRAX (WOOLSORTER’S DISEASE)

Edema toxin mimics adenylate cyclase increasing cAMP.

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43
Q

Gram+ rod
Spore-forming (heat resistant)
Associated with food poisoning

A

BACILLUS CEREUS

Produces preformed, heat stable toxin (Cereulide) causing reheated rice syndrome (results in spore germination).

N/V within 1-5 h of rice and pasta, or watery non-bloody diarrhea within 8-18 h.

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44
Q

Gram+ rod
Spore-forming (heat resistant)
Obligate anaerobe

A

CLOSTRIDIA

C. tetani
C. botulinum
C. perfringens
C. difficile

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45
Q

Spastic paralysis
Trismus (lockjaw)
Risus sardonicus (raised eyebrows, open grin)

A

TETANUS

C. tetani Tetanospasmin cleaves SNARE - Blocks spinal cord release of inhibitory neurotransmitters (GABA, Glycine)

Prevent with vaccine. Treat with antitoxin, diazepam for spasms, and wound debridement.

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46
Q

Diplopia, Dysphonia, Dysphagia
Descending flaccid paralysis
Anticholinergic signs
In infants presents as “floppy baby”

A

BOTULISM

C. botulinum heat-labile exotoxin cleaves SNARE - Blocks release of excitatory Ach at NMJ.

Note - Preformed toxin in canned foods, spores in honey

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47
Q

Myonecrosis of wound
Crepitus
Hemolysis (double zone on blood agar)

A

GAS GANGRENE

C. perfringens a-toxin (Lecithinase phospholipase).

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48
Q

Food poisoning (watery diarrhea) from undercooked, standing, or reheated meat.

A

C. PERFRINGENS

Heat-labile enterotoxin unlike B. cereus and S. aureus which are heat-stable.

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49
Q

Diarrhea following Clindamycin/Ampicillin (PPI increases risk)

Pseudomembranes (fibrin deposition) on colonoscopy

A

C. DIFFICILE

Enterotoxin A - Recruits and activates neutrophils leading to inflammation and diarrhea

Cytotoxin B - Inactivates Rho-regulatory proteins leading to cytoskeletal actin depolymerization causing necrosis and pseudomembrane formation

Toxin PCR assay for diagnosis

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50
Q 
Gram+ club-shaped rod
Loeffler's medium
Methylene Blue - Metachromatic granules
Cystine-Tellurite agar - Black colonies
Elek test+ (toxin)
A

CORYNEBACTERIUM DIPHTHERIAE

Produces Diphtheria exotoxin

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51
Q 
Pseudomembranous pharyngitis (gray-white)
Cervical lymphadenopathy
Myocarditis
Arrhythmias
Local neuropathy (soft palate paralysis)
A

DIPHTHERIA

Exotoxin inhibits protein synthesis via ADP-ribosylation of EF-2 - required for peptide chain translocation

Note - Vaccine is IgG against exotoxin B subunit preventing clinical sequelae

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52
Q

Gram+ rod
Facultative anaerobe (avoids antibodies)
Facultative intracellular
Tumbling motility and rocket tails (actin polymerization)
Lives in unpasteurized dairy products and cold deli meat

A

LISTERIA MONOCYTOGENES

Causes amnionitis, septicemia, spontaneous abortions, and granulomatosis infantiseptica in pregnant women.

Causes meningitis in the immunocompromised, young, or elderly - only mild gastroenteritis in healthy individuals.

Treat with Ampicillin.

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53
Q 
Gram+ branching filamentous
Weakly acid fast
Aerobic
Catalase+
Colonizes soil
A

NOCARDIA

Cutaneous involvement in immunocompetent
TB mimic in immunocompromised (normal PPD)
Brain abscess

Treat with Sulfonamides/TMP-SMX (“SNAP”).

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54
Q

Gram+ branching filamentous
Anaerobe
Yellow “sulfur” granules (grossly)
Colonizes oropharynx, GU, GI

Note - Sulfur granules become blue with H/E

A

ACTINOMYCES

Causes…
Orofacial abscesses
PID with IUDs

Treat with Penicillin (“SNAP”)

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55
Q 
Acid fast (pink) rods (Gram+ but does not stain)
Facultative intracellular
A

MYCOBACTERIUM

M. tuberculosis
M avium
M leprae
M scrofulaceum (cervical lymphadenitis in children)
M marinum (hand infection in aquarium handlers)

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56
Q 
Causes...
Productive or nonproductive cough
Hemoptysis
Fever
Night sweats
Weight loss
A

M. TUBERCULOSIS

Cord Factor/Trehalose creates “Serpentine Cord” in virulent M tuberculosis strains - Inhibits macrophage maturation and induces release of TNF-a

Sulfatides inhibit fusion of lysosomes to phagosomes - Allows for intracellular survival

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57
Q

Disseminated non-TB disease in AIDs patients…

Constitutional signs
Diarrhea
Anemia
Hepatosplenomegaly

Elevated AlkP
Elevated LDH
Acid fast culture growing at 41 deg C

A

M. AVIUM

Prophylaxis with Azithromycin when CD4 < 50

Treat with (Clarithromycin or Azithromycin) + (Ethambutol or Rifabutin)

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58
Q

Infection of skin and superficial nerves resulting in a glove and stocking loss of sensation.

Likes cool temperatures and reservoir in Armadillos.

A

M. LEPROSY (HANSEN DISEASE)

Lepromatous
Diffuse distribution with lion-like facies
Communicable and lethal
Low cell-mediated immunity with humoural Th2 response

Tuberculoid
Few hypoesthetic, hairless skin plaques
High cell-mediated immunity with Th1 response

Treatment
Dapsone + Rifampin
Add Clofazimine for Lepromatous form

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59
Q

Gram- lab algorithm.

A

Diplococci (Aerobic):
Maltose+ = N meningitidis
Maltose- = N gonorrhoeae, Moraxella

Coccobacilli:
HIB, Bordella pertussis

Comma-shaped rods (Oxidase+):
Grows in 42 deg C = Campylobacter jejuni
Grows in alkaline media = Vibrio cholerae
Urease+ = H. pylori

Bacilli:
Lactose fermentation test

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60
Q

Gram- bacilli algorithm.

A

Lactose fermentation+
Fast = Klebsiella, E. coli
Slow = Serratia

Lactose fermentation-:
Oxidase test

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61
Q

Gram - bacilli, non-lactose fermenting algorithm.

A

Oxidase-:
H2S production on TSI agar = Salmonella, Proteus
No H2S production on TSI agar = Shigella, Yersinia

Odiaze+:
Pseudomonas

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62
Q 
Gram- bean-shaped diplococci
Aerobic
Glucose fermentation+
Maltose-
Facultative intracellular (neutrophils)
Transmitted sexually or perinatally
A

NEISSERIA GONORRHOEAE

Causes Gonorrhea, Septic arthritis, Conjunctivitis (neonatal), PID, and Fitz-Hugh-Curtis syndrome

Virulence factors include Fimbriae and Pilus protein - Antigenic variation allows for reinfection

Treat with Ceftriaxone (+Azithromycin or Doxycycline for Chlamydia)

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63
Q 
Gram- diplococci
Aerobic
Glucose fermentation+
Maltose+
Encapsulated
Facultative intracellular
Transmitted via respiratory or oral secretions
A

NEISSERIA MENINGITIDIS

Causes…
Meningitis
Meningococcemia (petechial hemorrhages, gangrene)
Waterhouse-Friderichsen syndrome (adrenal insufficiency DIC, septic shock)

Treat with Ceftriaxone or Penicillin G

Close contact prophylaxis with Ceftriaxone or Ciprofloxacin or Rifampin

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64
Q 
Gram- coccobacillus rod
Grown on chocolate agar (V/X)
Grown with S. aureus (V)
Encapsulated (typeable)
Biofilm producing
Transmitted by aerosols
A

HAEMOPHILUS INFLUENZAE

Causes epiglottitis, meningitis, otitis media, pneumonia (“haEMOPhilus”)

Capsule (type B) uses PRP to bind factor H and degrade C3b

Vaccine allows binding of C3b to Fc region of IgG - Not degraded by factor H

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65
Q

Gram- coccobaccilus
Aerobic
Bordet agar
Lymphocytic infiltrate

A

BORDETELLA PERTUSSIS

Causes whooping cough - catarrhal URI, paroxysmal (whooping, emesis), and convalescent stage

Produces Pertussis toxin - Over-activates adenylate cyclase (disables Gi) increasing cAMP impairing phagocytosis

Note - Increased cAMP increases serum Insulin

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66
Q

Silver stain rod (Gram- but does not stain)
Grown on charcoal (L-Cysteine)
Transmitted by aerosols from water source
Facultative intracellular
No person-person transmission

A

LEGIONELLA PNEUMOPHILA

No gram staining due to unique polysaccharide chains on outer membrane

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67
Q 
In a smoker or COPD patient...
Relative bradycardia
Unilateral lobar pneumonia
GI symptoms
CNS symptoms
Hyponatremia !!
Neutrophils with no bacteria
A

LEGIONNAIRES DISEASE (LEGIONELLA)

Pontiac fever is a mild-flu like form

Confirm with urine antigen test
Treat with Macrolide

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68
Q 
Gram- rod
Aerobic
Lactose fermentation-
Oxidase+
Encapsulated
Biofilm producing
Blue-green pigment (Pyocyanin)
Grape-like odor
A

PSEUDOMONAS AERUGINOSA

Causes...
Pneumonia (ventilator)
UTIs
Osteomyelitis
Otitis externa
Skin infections (burn victims, hot-tub folliculitis)
Bacteremia/Ecthyma Gangrenosum
Produces...
Endotoxin
Exotoxin A (inactivates EF-2)
Elastase
PLC (degrades cell membrane)
Pyocyanin (generates ROS)
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69
Q

Treatments for Pseudomonas.

“CAMPFIRE”

A 
Carbapenems
Aminoglycosides
Monobactams
Polymyxin
Fluoroquinolones
thIRd/fourth generation cephalosporins
Extended-spectrum penicillins (piperacillin, ticarcillin)
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70
Q

Rapidly progressive, necrotizing cutaneous lesion in immunocompromised patients.

A

ECTHYMA GANGRENOSUM

Pseudomonas bacteremia.

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71
Q 
Gram- rod
Encapsulated
Lactose fermentation+
Indole+
Catalase+
b-galactosidase+ (lactose = glucose + galactose)
Pink on MacConkey's agar
Green sheen on EMB (other lactose fermenters black)
A

E. COLI

Produces endotoxin

Virulence factors include Fimbriae/P-pili (cystitis, pyelonephritis) and K capsule (pneumonia, meningitis).

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72
Q

Strain of e. coli causing invasive dysentery (bloody diarrhea with pus).

A

EIEC

Invades GI mucosa and causes necrosis and inflammation.

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73
Q

Strain of e. coli causing traveler’s diarrhea (watery diarrhea).

A

ETEC

Produces heat-labile/stable enterotoxin - no invasion or inflammation of GI mucosa.

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74
Q

Strain of e. coli causing pediatric diarrhea.

A

EPEC

Adheres to apical surface and flattens villi, preventing absorption.

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75
Q

Strain of e. coi causing…
Non-invasive dysentery (erythrocytes in stool)
HUS (anemia with schistocytes, thrombocytopenia, ARF)

Transmitted by undercooked meat and raw leafy vegetables

A

EHEC (O157:H7)

Shiga-like toxin (SLT) inactivates 60s ribosome (removes adenine from rRNA) enhancing cytokine release - Microthrombi form on damaged renal endothelium

Unlike other e. coli does not ferment sorbitol

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76
Q

Gram- rod
Lactose fermentation+
Encapsulated
Colonizes GI tract

A

KLEBSIELLA

Causes…
Lobar antimicrobial aspiration pneumonia with mucoid currant jelly sputum (diabetes, alcoholics)
Nosocomial UTIs
Abscesses (lungs, liver)

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77
Q

Gram- comma-shaped rod
Oxidase+
Grows in 42 deg C
Polar flagella

Transmitted fecal-oral

A

CAMPYLOBACTER JEJUNI

Causes…
Bloody diarrhea
GBS
Reactive arthritis

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78
Q 
Gram- rod
Lactose fermentation-
Oxidase-
H2S production on TSI agar
Facultative intracellular
Flagella (hematogenous dissemination) with antigenic variation
A

SALMONELLA

Requires high inoculum - primarily monocytic response if s. typhi (s. spp. PMNs if disseminated)

Produces endotoxin
S. typhi produces Vi capsule

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79
Q 
Gram- rod
Lactose fermentation-
Oxidase-
No H2S production on TSI agar
No flagella (cell to cell spread only)
A

SHIGELLA

Requires low inoculum - primarily neutrophil infiltration response

Produces endotoxin
Produces Shiga toxin

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80
Q 
Initial constipation
Diarrhea (monocytic infiltrate)
Rose spots on abdomen
Abdominal pain
Hepatosplenomegaly
Fever
Relative bradycardia

Transmitted by fecal-oral

A

TYPHOID FEVER (SALMONELLA TYPHI)

Carrier state with gallbladder colonization

Treat with…
Ceftriaxone or Fluoroquinolone (prolongs fecal excretion)

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81
Q

Causes self-limiting gastroenteritis (no antibiotics indicated) - Reservoirs in turtles, poultry, and eggs.

A

SALMONELLA SPP.

Taken up by M cells and then infects and survives within macrophages

Note - Can cause mesenteric adenitis unlike Shigella

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82
Q

Bloody diarrhea with pus (dysentery)

Transmitted by fingers/flies in food/feces

A

SHIGELLOSIS

Mucosal invasion via intracellular host actin polymerization

Shiga toxin (ST) inactivates 60S ribosome by removing adenine from rRNA leading to GI mucosal damage, and also cytokine release (HUS)

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83
Q

Gram- comma-shaped rod
Oxidase+
Grows in alkaline media
Unipolar flagella

A

VIBRIO CHOLERAE

Toxin over-activates adenylate cyclase (permanently activates Gs) increasing cAMP - Increased Cl-/H2O secretion (rice-water diarrhea)

Treat with oral rehydration

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84
Q 
Gram- rod
Lactose fermentation-
Oxidase-
No H2S production on TSI agar
Facultative intracellular
Transmitted by farm animals
A

YERSINIA ENTEROCOLITICA

Causes…
Acute bloody diarrhea
Pseudo-appendicitis (mesenteric adenitis, terminal ileitis)

Yersinia pestis causes plague

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85
Q 
Gram- comma-shaped rod
Oxidase+
Catalase+
Urease+
Flagellum
A

HELICOBACTER PYLORI

Risk factor for ulcer disease, gastric adenocarcinoma, and MALT lymphoma

Urease produces ammonia to allow survival in antrum of stomach during chemotaxis to mucus/epithelium

Diagnosed by urea breath test or fecal antigen testing. Treat with Amoxicillin or Metronidazole + Clarithromycin + PPI

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86
Q

Spiral-shaped
Axial filament
Transmitted by water contaminated by animal urine

A

LEPTOSPIRA INTERROGANS (SPIROCHETE)

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87
Q 
Surfer or patient in the tropics with...
Flu-like symptoms
Myalgia (calves)
Jaundice
Photophobia
Conjunctival suffusion (erythema without exudate)
A

LEPTOSPIROSIS

Weil disease is a severe form (icterohemorrhagic) that also presents with azotemia (kidney dysfunction), hemorrhage, and anemia.

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88
Q

Spiral-shaped
Giemsa stain
Axial filament
Transmitted by Ixodes

A

BORRELIA BURGDORFERI (SPIROCHETE)

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89
Q

Early:
Flu-like symptoms
Localized erythema migrans

Disseminated secondary lesions
Carditis with AV block
Bilateral facial nerve (Bell) palsy
Migratory/transient myalgia/arthralgia

Late:
Disseminated encephalopathies
Chronic arthritis

A

LYME DISEASE

Treat with Doxycycline or Ceftriaxone

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90
Q

Spiral-shaped
Dark-field microscopy
Axial filament

A

TREPONEMA PALLIDUM (SPIROCHETE)

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91
Q

Painless chancre

A

PRIMARY SYPHILIS

Dark-field microscopy on fluid from chancre, or VDRL.

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92
Q

Fever
Maculopapular rash (including palms/soles)
Condylomata lata (painless wart-like white lesions)
Lymphadenopathy

A

SECONDARY SYPHILIS

Confirm with dark-field microscopy, or VDRL/RPR (sensitive, responsive) followed by FTA-ABS (specific, life-long)

May progress to serologically positive, asymptomatic latent phase

93
Q 
Gummas (chronic granulomas)
Aortitis (vaso vasorum destruction)
Argyll-Robertson pupil (accommodates only)
General paresis
Tabes dorsalis
Broad-based ataxia
Romberg sign
Charcot joint
A

TERTIARY SYPHILIS

For neurosyphilis LP with VDRL, FTA-ABS, PCR

94
Q

Often stillbirth or hydrops fetalis

If survives...
Saddle nose
Short maxilla
Notched teeth
Mulberry molars
Saber shins
CN VIII deficits
A

CONGENITAL SYPHILIS

Treat mother before first trimester

95
Q

False-positives on VDRL.

“VDRL”

A

Viral infections (EBV, hepatitis)
Drugs
Rheumatic fever
Lupus/Leprosy

96
Q

Flu-like syndrome after treating syphilis.

A

JARISCH-HERXHEIMER REACTION

Killer bacteria release toxins.

97
Q

Gray vaginal discharge
Fishy smell
No inflammation
Nonpainful

Clue cells (vaginal epithelium covered with bacteria)
pH > 4.5
A

BACTERIAL VAGINOSIS

Caused by Gardnerella vaginalis (gram variable, pleomorphic)

Amine whiff test (with KOH) produces fishy odor

Treat with Metronidazole or Clindamycin - not sexually transmitted to partners

98
Q

Rash spreading from wrists/ankles to palms/soles
Headache
Fever

Vector is tick
Giemsa stain

A

ROCKY MOUNTAIN SPOTTED FEVER

Rickettsia rickettsii

Treat with Doxycycline

99
Q

Central rash spreading out - spares palms and soles

Vector is lice

A

TYPHUS

Rickettsia typhus/prowazekii

Treat with Doxycycline

100
Q

Flu-like symptoms

Monocytes with morulae (mulberry-like cytoplasmic inclusions)

Vector is tick

A

EHRLICHIOSIS

Treat with Doxycycline

101
Q

Flu-like symptoms

Granulocytes with morulae (mulberry-like cytoplasmic inclusions)

Vector is tick

A

ANAPLASMOSIS

Treat with Doxycycline

102
Q 
Fever
Constitutional signs
Pneumonia
Retro-orbital headache
Thrombocytopenia
Transaminitis
Normal leukocyte count
Culture negative endocarditis

Transmitted by aerosolized spores from cattle/sheep waste - No arthropod vector

A

Q FEVER

Coxiella burnetti - Obligate intracellular parasite requires cell media to grow

Treat with Doxycycline

103
Q

Cytoplasmic inclusions seen on Giemsa or fluorescent antibody stain.

A

CHLAMYDIAE

Elementary body enters cell via endocytosis, transforms into reticulate body to replicate by fusion

Chlamydial cell wall lacks peptidoglycan (reduced muramic acid) making B-lactams less effective

104
Q 
Causes...
Reactive arthritis (Reiter syndrome)
Follicular conjunctivitis
Nongonococcal urethritis/PID
Neonatal pneumonia 
Neonatal conjunctivitis
A

CHLAMYDIA TRACHOMATIS

Chlamydia pneumoniae and psittaci cause atypical pneumonia (aerosolized)

Types A/B/C cause follicular conjunctivitis and chronic infection, types D-K cause everything else

Treat with Azithromycin

105
Q

Small, painless ulcers on genitals

Swollen, painful inguinal lymph nodes (ulcerating)

A

LYMPHOGRANULOMA VENEREUM

Treat with Doxycycline.

106
Q 
Insidious onset of...
Malaise
Nonproductive cough
Low-grade fever
Erythema multiforme
Patchy or diffuse interstitial infiltrates on CXR
High titer cold agglutinins (IgM)
SJS

Culture grown on Eaton agar with cholesterol
Pleomorphic with no cell wall, membrane, capsule so Gram stain/Penicillin resistant

Common among military recruits and prisoners

A

MYCOPLASMA ATYPICAL PNEUMONIA

Treat with Macrolides, Doxycycline, or Fluoroquinolones

107
Q

Mold with hyphae in cold
Numerous oval yeast within macrophages in heat
Smaller than RBC

Common among river valleys
Reservoir is bird or bat droppings (caves)

A

HISTOPLASMOSIS

Causes…
Granulomatous lung disease with calcified nodes (e.g. TB)
Hepatosplenomegaly (reticuloendothelial system)
Painful oral ulcers

Fluconazole or Itraconazole if local
Amphotericin B if systemic

Note - Itraconazole prophylaxis if HIV+, CD4 < 150, and in endemic area

108
Q

Mold with hyphae in cold
Large, round yeast with doubly refractile wall in heat
Single broad-based budding - same size as RBC

Common in the east third of US

A

BLASTOMYCOSIS

Forms granulomatous nodules and causes…
Pneumonia
Disseminate to skin/bone

Fluconazole or Itraconazole if local
Amphotericin B if systemic

109
Q

Mold with hyphae in cold
Thick-walled spherules in heat
Spherules filled with endospores - much larger than RBC

Common in SW US dust

A

COCCIDIOMYCOSIS

Causes…
Flu-like illness
Dissemination to skin (erythema nodosum), bone (arthralgias), and meninges

Fluconazole or Itraconazole if local
Amphotericin B if systemic

110
Q

Multiple blastoconidia in cold
Budding yeast with captain wheel’s formation (cells covered in budding blastoconidia) in heat
Much larger than RBC

Common in Latin America

A

PARACOCCIDIOIDOMYCOSIS

Chronic cutaneous or mucocutaneous ulcers - can progress to lung and lymph nodes

111
Q

Infections caused by dermatophytes - Microsporum, Trichophyton, Epidermophyton

Branching septate hyphae on KOH with blue fungal stain

A 
Tinea capitis - alopecia and scaling
Tinea corporis - scaling rings with central clearing (ringworm)
Tinea cruris - no central clearing
Tinea pedis - interdigital or moccasin
Tinea unguium - onychomycosis

Treat with topical Terbinafine or oral Griseofulvin

112
Q

Well demarcated hyper or hypopigmented salmon-colored lesions on the trunk

“Spaghetti and Meatballs” appearance on KOH

A

TINEA (PITYRIASIS) VERSICOLOR

Malassezia spp. (yeast) causes degradation of lipids producing acids that damage melanocytes.

Treat with Ketoconazole with Selenium Sulfide lotion

113
Q

White dimorphic yeast
Pseudohyphae with budding/blastoconidia when cold
Germ tubes when warm

Note - Colonizes oral cavity (sputum contaminant)

A

CANDIDA ALBICANS

Diaper rash
Thrush
Vulvovaginitis (diabetes, antibiotic use)
Chronic mucocutaneous candidiasis
Endocarditis (IVDU)
Disseminated candidiasis (indwelling catheters)

Note - IE/Disseminated candida due to neutropenia (e.g. malignancy) rather than T-cell deficiency (e.g. HIV)

114
Q

Treatment for candidiasis (vaginal, oral/esophageal, systemic).

A 
Vaginal = Topical Azole
Oral/Esophageal = Nystatin, Fluconazole, or Caspofungin
Systemic = Fluconazole, Caspofungin, or Ampho B
115
Q

Fungal hyphae
Hyphae branching at acute angles
Conidia (radiating flower-like chains) at end of conidiophore

A

ASPERGILLUS FUMIGATUS

116
Q 
Immunocompromised patient with...
Fever
Chest pain
Cough
Dyspnea
Hemoptysis
A

INVASIVE ASPERGILLOSIS

May grow on food and produce Aflatoxins - Inhibit p53 and lead to HCC

Treat with IV AmphoB, Voriconazole, or Caspofungin

Note - May also form fungus balls (colonization) in pre-existing cavities (e.g. TB)

117
Q

Hypersensitivity response in patients with asthma and cystic fibrosis - Causes bronchiectasis and eosinophilia.

A

ALLERGIC BRONCHOPULMONARY ASPERGILLOSIS (ABPA)

Diagnose with serologic testing and skin hypersensitivity

118
Q

Narrow budding yeast with thick capsules - not dimorphic
Soil and pigeon droppings along western US

Culture on Sabouraud agar
India ink makes clear halo
Mucicarmine highlights red inner capsule
Latex agglutination most specific for capsule

A

CRYPTOCOCCUS NEOFORMANS

Aerosolized (HIV) - Cryptococcosis (lung)
Disseminated - Meningoencephalitis

Only pathogenic fungus with antiphagocytic capsule

Treat with IV AmphoB with Flucytosine for 2 weeks, then oral Fluconazole

119
Q

Broad ribbon-like hyphae
No septae
Right angle branching

A

MUCOR/RHIZOPUS SPP

120
Q 
In a ketoacidotic diabetic or neutropenic patient...
Headache
Facial pain
Black necrotic eschar on face
Cranial nerve involvement

Rhinocerebral abscess, frontal lobe abscess, or cavernous sinus thrombosis on MRI

A

MUCORMYCOSIS

Proliferate in blood vessel walls and penetrate cribriform plate to enter brain

Surgical debridement with IV AmphoB

121
Q

Diffuse interstitial pneumonia in AIDs patient

Disc-shaped yeast on Methenamine silver stain (lung biopsy or lavage)

Diffuse, bilateral ground-glass opacities on CXR/CT

A

PNEUMOCYSTIS PNEUMONIA

Pneumocystis jirovecii (yeast-like fungus)

Prevent with TMP-SMX when CD4 < 200. Treat with TMP-SMX or Pentamidine

122
Q

Local pustule or ulcer with nodules along draining lymphatics (ascending lymphangitis) - may disseminate if immunocompromised.

A

SPOROTRICHOSIS (ROSE GARDENER’S DISEASE)

Sporothrix schenckii - Dimorphic fungus (mold with hyphae in cold, cigar-shaped budding yeast in heat)

Treat with Itraconazole or Potassium Iodide

123
Q

Protozoa causing…
Bloating
Flatulence
Foul-smelling fatty diarrhea

Villous atrophy with crypt hyperplasia
Cysts in water

A

GIARDIASIS

Giardia lamblia - Diagnose with multinucleated ellipsoid cysts in stool

Treat with Metronidazole

124
Q 
Protozoa causing...
Bloody diarrhea (dysentery)
RUQ pain
Liver abscess (anchovy paste exudate)
Flask shaped ulcers

Cysts in water

A

AMEBIASIS

Entamoeba histolytica - Diagnose with serology, trophocytes with engulfed RBCs in cytoplasm, or multinucleated cysts in stool

Treat with Metronidazole or Iodoquinol (asymptomatic)

125
Q

Protozoa causing severe diarrhea in HIV patient
Non-ulcerative inflammation
Basophilic clusters on mucosa

Oocytes in water

A

CRYPTOSPORIDIUM

Diagnose with oocyst on acid-fast stain

Prevent by filtering water
Treat with Nitazoxanide (immunocompetent only)

126
Q

Protozoa causing…

In neonates triad of…
Chorioretinitis
Hydrocephalus
Intracranial calcifications

In AIDs patients…
Ring-enhancing lesions on MRI

A

TOXOPLASMOSIS

Toxoplasma gondii - cysts in meat, oocyte in cat feces

Diagnose with serology, or tachyzoite on biopsy

Treat with TMP-SMX/Pyrimethamine

127
Q

Protozoa causing rapidly fatal meningoencephalitis

Transmitted by fresh-water and enters CNS via cribriform plate

A

NAEGLERIA FOWLERI

Diagnose with amoebas in LP

Treat with Ampho B

128
Q 
Protozoa causing...
Enlarged lymph nodes
Recurring fever (antigenic variation)
Somnolence
Coma

Transmitted by the Tsetse fly
Giemsa stain

A

AFRICAN SLEEPING SICKNESS

Trypanosoma brucei (antigenic variation) - diagnose with trypomastigotes in blood smear

Suramin for fever
Melarsoprol if CNS penetration (somnolence)

129
Q 
Protozoa causing...
Fever
Headache
Anemia
Splenomegaly

Transmitted by Anopheles

A

MALARIA

P vivax/ovale = 48 h fever cycle with hypnozoite in liver
P malariae = 72 h fever cycle
P falciparum = severe/irregular fever cycle and occlusion of capillaries in brain (cerebral malaria), kidneys, and lung

Diagnose with trophozoite ring within RBC - divides and releases as merozoites

Before treatment test for G6PD deficiency as malarial drugs induce oxidative stress

130
Q 
Protozoa causing...
Fever
Fatigue/Myalgia
Hemolytic anemia
Thrombocytopenia
Transaminitis
Ring or Maltese Cross on wright/giemsa stain

Transmitted by Ixodes tick (co-infection with Lyme)

A

BABESIOSIS

Treat with Atovaquone + Azithromycin

Note - If severe (e.g. asplenic patients) may present with ARDS, DIC

131
Q

Protozoa causing…
Acutely unilateral periorbital swelling

Dilated cardiomyopathy with apical atrophy
Megacolon
Megaesophagus

Transmitted by Reduviid bug
Giemsa stain

A

CHAGAS DISEASE

Trypanosoma cruzi (antigenic variation) - diagnose with trypomastigote in blood smear

Treat with Benznidazole or Nifurtimox (“CRUZIng in my BENZ with a FUR coat on”)

132
Q

Protozoa causing…
Spiking fevers
Hepatosplenomegaly
Pancytopenia

Transmitted by sandfly

A

VISCERAL LEISHMANIASIS

Cutaneous form presents with only skin ulcers

Leishmania donovani - diagnose with macrophages containing amastigotes

Treat with Sodium Stibogluconate or AmphoB

133
Q 
Protozoa causing...
Frothy, green vaginal discharge
Foul smelling
Inflammation (strawberry cervix)
Itching and burning

pH > 4.5
Motile trophozoites on wet mount

A

TRICHOMONAS VAGINITIS

Treat with Metronidazole - also treat partners (STI)

134
Q

Intestinal nematode infection causing anal pruritus

Transmission is fecal-oral

A

PINWORMS

Enterobius vermicularis - diagnosed by eggs on tape test

Treat with Bendazoles (Pyrantel Pamoate if pregnant)

135
Q

Intestinal nematode infection with obstruction of ileocecal valve

Transmission is fecal-oral

A

GIANT ROUNDWORM

Ascaris lumbricoides - diagnosed by eggs in feces

Treat with Bendazoles

136
Q

Intestinal nematode infection causing vomiting, diarrhea, and epigastric pain (mimics peptic ulcer) - may result in autoinfection and shock

Transmission is cutaneous

A

STRONGYLOIDES

Diagnosed with rhabditiform (non-infectious) in the stool

Treat with Ivermectin

137
Q

Intestinal nematode infection causing…
Microcytic anemia
Cutaneous larva migrans (pruritic, serpiginous rash)

Transmission is cutaneous

A

HOOKWORM

Ancylostoma duodenale or Necator americanus

Treat with Pyrantel pamoate or Bendazoles

138
Q 
Intestinal nematode infection causing...
Fever
N/V
Periorbital edema
Myalgia

Transmission is fecal-oral and by undercooked pork

A

TRICHINOSIS

Trichinella spiralis

Treat with Bendazoles

139
Q

Nematode causing…
Myocarditis
Seizures
Liver damage

Transmission is fecal-oral

A

VISCERAL LARVA MIGRANS

Toxocara canis - migrate to blood through intestinal wall

Treat with Bendazoles

140
Q

Nematode causing…
Black skin nodules
Loss of elastic fibers
Blindness

Transmission by female blackfly

A

RIVER BLINDNESS

Onchocerca volvulus

Treat with Ivermectin

141
Q

Nematode causing…
Swelling in skin
Worm in conjunctiva

Transmission by horse/deer fly

A

LOA LOA

Treat with Diethylcarbamazine

142
Q

Nematode invading lymph nodes and causes inflammation, which blocks lymphatic vessels and eventually causes elephantiasis

Transmission by female mosquito

A

WUCHERERIA BANCROFTI

Treat with Diethylcarbamazine

143
Q

Cestode causing…
Intestinal tapeworm
Cysticercosis

Transmission by larvae in undercooked pork
Transmission by eggs from human feces

A

TAENIA SOLIUM

Treat with Praziquantel

144
Q

Cestode causing megaloblastic anemia (vit B12 deficiency)

Transmission by larvae in raw freshwater fish

A

DIPHYLLOBOTHRIUM LATUM

Treat with Praziquantel

145
Q

Cestode causing hydatid cysts in liver
Eggshell calcifications on microscopy

Transmission by eggs from dog feces, lives in sheep

A

ECHINOCOCCUS GRANULOSUS

Treat with Albendazole - Inject cyst with Ethanol/NaCl before removal to prevent Anaphylaxis

146
Q 
Trematode causing...
Dermatitis
Intestinal obstruction
Hepatosplenomegaly
Portal HTN
Hematuria
Hydronephrosis/Pyelonephrosis
Katayama fever (allergic)

Chronically…
Fibrosis of bowel, bladder, liver
Squamous cell carcinoma of bladder
Pulmonary hypertension

Transmission is cutaneous, lives in snails

A

SCHISTOSOMA

Note - Periportal pipestem fibrosis is pathognomonic

Treat with Praziquantel

147
Q

Trematode causing biliary tract inflammation leading to pigmented gallstones and cholangiocarcinoma.

Transmission is by undercooked fish

A

CLONORCHIS SINENSIS

Treat with Praziquantel

148
Q

Mites that burrow into the stratum corneum and cause serpiginous burrows in webspace of hands and feet, and intense pruritus.

A

SARCOPTES SCABIEI

Treat with Permethrin cream - also treat close contacts

149
Q

Blood sucking insects causing intense pruritus, pink macules, and papules in intertriginous regions.

A

PEDICULUS HUMANUS/PHTHIRUS PUBIS

150
Q

Live attenuated vaccines - Humoral and cell-mediated immunity (no booster) but avoid in immunocompromised patients.

A 
MMR (give to HIV if not AIDs)
Chickenpox
Influenza (intranasal)
Sabin polio (oral)
Rotavirus
Smallpox
Yellow fever
BCG
151
Q

Killed (inactivated) vaccines - Humoral immunity only

A

Rabies
Influenza (IM)
Salk polio (IM)
HAV

Note - Tetanus/Diptheria/Botulism are toxoid vaccines

152
Q

Subunit vaccines.

A 
HBV
HPV
Pertussis
HiB
PCV
Meningococcal
153
Q

DNA viruses

“HHAPPPPy”

A 
Hepadna (partially ds, circular)
Herpes
Adeno
Pox
Parvo (ssDNA, "parvo a virus")
Papilloma (circular)
Polyoma (circular)
154
Q

Flesh-colored papule with central umbilication.

A

MOLLUSCUM CONTAGIOSUM

Poxvirus - Only DNA virus with own DNA-dependent RNA polymerase thus only DNA virus replicating outside of the nucleus

155
Q 
Year-round virus causing...
Febrile pharyngitis
Acute hemorrhagic cystitis
Pneumonia
Conjunctivitis
Watery diarrhea
A

ADENOVIRUS

156
Q

Virus causing…
Progressive multifocal leukoencephalopathy (PML)
BK virus (targets kidneys) in transplant patients

A

POLYOMAVIRUS

157
Q

Virus causing…
Erythema infectiosum - Slapped cheeks rash followed by lacy reticular rash
Pure RBC aplasia with arthritis in adults
Aplastic crisis in SCD (pure anemia)
Hydrops fetalis (RBC destruction)

A

PARVOVIRUS

Note - Infects erythrocyte progenitors in bone marrow via blood group P antigen

158
Q

Virus causing…
Gingivostomatitis (primary; severe oropharynx)
Keratoconjunctivitis
Herpes labialis (reactivation; cold sore)
Herpetic whitlow
Erythema multiforme
Temporal lobe encephalitis

Transmitted by respiratory and oral secretions, or intrapartum

A

HSV-1

Most common cause of sporadic encephalitis - viral meningitis more common with HSV-2

Valacyclovir (prodrug - better oral availability)

159
Q

Virus causing…
Varicella-Zoster
Encephalitis
Pneumonia

Transmitted by respiratory secretions

Note - As part of TORCH causes limb hypoplasia, cutaneous scarring, chorioretinitis, and cataracts

A

VARICELLA-ZOSTER (HHV-3)

Latent in dorsal root and trigeminal ganglion - HSV-2 latent in sacral ganglion

Famciclovir

160
Q 
Virus causing...
Fever
Hepatosplenomegaly
Pharyngitis
Cervical lymphadenopathy
Atypical lymphocytosis
Increased risk of Burkitt lymphoma
Increased risk of nasopharyngeal carcinoma

Transmitted by respiratory and oral secretions

A

EPSTEIN-BARR VIRUS MONONUCLEOSIS (HHV-4)

Infects B cells via CD21 and causes clonal proliferation- Atypical lymphocytes (reactive cytotoxic T cells) on peripheral smear

Diagnose with monospot test detects heterophile antibodies by agglutination

Avoid contact sports until resolution due to risk of splenic rupture

161
Q

Virus causing…
Monospot (agglutination) negative mononucleosis
Pneumonitis in transplant patients
Esophagitis, Colitis, and Retinitis in AIDS patients
SJS

Transmitted by sexual contact, oral secretions, urine, and transplant

A

CYTOMEGALOVIRUS (HHV-5)

Latent in mononuclear cells, basophilic owl eye inclusions on smear

Note - prophylaxis with Valganciclovir in transplant patients

162
Q

Virus causing…
High fever with febrile seizures for several days
Followed by diffuse macular rash starting on the trunk

Transmitted by oral secretions

A

HHV-6/7

Roseola infantum/exanthem subitum - Infects lymphocytes

163
Q

Virus causing…

Dark/violaceous plaques or nodules (vascular proliferations) in an HIV/AIDS or transplant patient

A

HHV-8

Kaposi sarcoma (endothelial cells)

164
Q

Detection of multinucleated giant cells caused by HHVs.

A

TZANCK SMEAR

For HSV-1, HSV-2, and VZV

165
Q

Enveloped DNA viruses - others are infective even when naked.

(“HHaPpppy”)

A

Herpes
Hepadna
Pox

166
Q

+ssRNA viruses - Do not require own RNA-dependent RNA polymerase (like -ssRNA viruses) to be infectious while naked

Most are also icosahedral capsid (-ssRNA helical)

(“RETRO TOGA party with FLAVa flav drinking CORONA and HEavy CALIfornia PICkles”)

A 
Retro
Toga
Flavi
Corona (common cold, SARS, MERS)
Hepe
Calici (Noro)
Picorna
167
Q

Segmented viruses.

“BOAR”

A

Bunyavirus
Orthomyxovirus
Arenavirus
Reovirus

168
Q

Picornaviruses.

“PERCH”

A 
Polio
Echo - Aseptic meningitis
Rhino - Common cold (uniquely not enterovirus)
Coxsackie
HAV
169
Q

High fever
Black vomitus
Jaundice

Transmitted by Aedes mosquito

A

YELLOW FEVER (FLAVIVIRUS/ARBOVIRUS)

Eosinophilic apoptotic globules on liver biopsy

Other flavivirus include Dengue

170
Q

Causes acute watery diarrhea during the winter - Incidence reduced due to vaccination

A

ROTAVIRUS (REOVIRUS)

Only dsRNA virus

Villous destruction with atrophy leads to decreased absorption of Na and renal K wasting

171
Q

Viral cause of influenza - at risk for fatal bacterial superinfection (S. aureus, S. pneumoniae, HIB).

A

ORTHOMYXOVIRUS

RNA virus that does not replicate in cytoplasm (other is retrovirus)

Hemagglutinin promotes viral entry, Neuraminidase promotes progeny virion release

Genetic shift (reassortment) more deadly than genetic drift (random mutations)

Note - Antibodies against Hemagglutinin prevent reinfection by same serotype

172
Q 
Virus causing...
Fever
Postauricular lymphadenopathy
Polyarthralgia
Forschheimer spots on soft palate
Pink coalescing macules begin at head and move down and form fine desquamating truncal rash
A

RUBELLA (TOGAVIRUS)

173
Q 
Seal-like barking cough
Inspiratory stridor
Pulsus paradoxus (>10 drop in SBP on inspiration)

Steeple sign on XR

A

CROUP/PARAINFLUENZA (PARAMYXOVIRUS)

Surface F protein causes respiratory epithelial cells to fuse and form multinucleated cells

174
Q

Virus causing…
Prodromal fever with cough, coryza, conjunctivitis
Koplik spots on buccal mucosa
Maculopapular rash starting at head/neck and spreading downward

May eventually result in subacute sclerosing panencephalitis (SSPE)

A

MEASLES/RUBEOLA (PARAMYXOVIRUS)

Surface F protein causes respiratory epithelial cells to fuse and form multinucleated cells

Vit A supplementation can reduce morbidity and mortality

175
Q 
Virus causing...
Parotitis
Orchitis
Aseptic meningitis
Pancreatitis

May result in sterility

A

MUMPS (PARAMYXOVIRUS)

Surface F protein causes respiratory epithelial cells to fuse and form multinucleated cells

176
Q

Virus causing bronchiolitis/pneumonia in babies - predominant during winter

A

RSV (PARAMYXOVIRUS)

Surface F protein causes respiratory epithelial cells to fuse and form multinucleated cells

Palivizumab (monoclonal antibody against F protein) for RSV pneumonia in premature infants

177
Q

Initially fever and malaise weeks to months after bite (bat, raccoon, skunk)

Later agitation, photophobia, hydrophobia, and hypersalivation

Eventually paralysis, coma, and death

A

RABIES VIRUS (RHABDOVIRUS)

Targets Nicotinic Ach receptors

Bullet-shaped with Negri (cytoplasmic inclusions) bodies in Cerebellar Purkinje cells or Hippocampal Pyramidal cells

Postexposure prophylaxis with wound cleaning, killed vaccine, and rabies immunoglobulin - start while observing if high risk animal

178
Q 
Virus causing...
Abrupt onset high fever
Diarrhea
N/V
Myalgia

May progress to DIC, diffuse hemorrhage, and shock

A

EBOLA (FILOVIRUS)

Targets endothelial cells, phagocytes, and hepatocytes

Diagnosed with RT-PCR. Treat with isolation and supportive care

Other filovirus includes Marburg hemorrhagic fever

179
Q

Virus causing hemorrhagic fever and pneumonia.

A

HANTAVIRUS (BUNYAVIRUS)

180
Q

Naked RNA viruses.

“CPR to a naked HIPpie”

A

Calici (Noro)
Picorna (PERCH)
Reo (Rota)
Hepe (HEV)

181
Q

Lack envelope so not destroyed by the gut
Fecal-oral transmission, Shellfish
Acute or asymptomatic infection
No carrier state

Hepatocyte swelling
Monocyte infiltration
Councilman (eosinophilic apoptotic) bodies
Hepatocyte hyperplasia with resolution

Note - Aversion to smoking

A

HAV (PICORNA)

IgM if acute infection, IgG if prior infection or vaccination

Note - Histology may appear in all cases of acute viral hepatitis (e.g. HBV, HCV)

182
Q

Enveloped
Parenteral, sexual, perinatal transmission

Acutely Fever, Arthralgia, Urticarial vasculitic rash, Lymphadenopathy, Hepatomegaly (tender), and Transaminitis (>10x normal)

Long incubation
Minority progress to HCC
Carrier state common

Granular pale eosinophilic cytoplasm (ground-glass)
Nodular regeneration if chronic

Note - Proliferative phase results in CD8+ mediated liver damage, while integrative phase increases risk of HCC (p53 silencing)

A

HBV (HEPADNA)

Viral polymerase completes dsDNA upon entry
Host RNA polymerase transcribes mRNA for proteins
Viral polymerase also reverse transcribes RNA to DNA for progeny genome

Note - Viral polymerase is reverse transcriptase (both DNA and RNA dependent DNA polymerase)

Note - Eosinophilic cytoplasm due to HBsAg within hepatocytes

183
Q 
Enveloped
Parenteral transmission
Long incubation may progress to cirrhosis/HCC
Majority develop chronic infection
Carrier state common

Lymphoid aggregates
Focal macrovesicular steatosis
Nodular regeneration if chronic

Note - No reverse transcriptase so no integration into host genome

A

HCV (FLAVI)

Lack of 3’-5’ exonuclease proofreading increases antigenic variation

Note - May result in cryoglobulinemia vasculitis (arthralgia, myalgia, purpura)

184
Q

Enveloped
Parenteral, sexual, perinatal transmission
Superinfection with HBV worsens prognosis

Requires presence of HBV to make viral envelope

A

HDV (DELTA)

185
Q

Lack envelope so not destroyed by gut
Fecal-oral transmission
Short incubation with fulminant hepatitis in pregnancy
High mortality during pregnancy but no HCC risk
No carrier state

Patchy necrosis

A

HEV (HEPE)

186
Q

HBsAg
HBeAg
anti-HBc IgM

A

Acute HBV

Women who deliver with HBeAg will have infants with high viral load/HBeAg but normal lab findings due to immune tolerance, and have a >90% chance of becoming chronically infected - treat with HBV-vaccine and immune globulin

187
Q

anti-HBc IgM

anti-HBe

A

Window period

188
Q

HBsAg
HBeAg
anti-HBc IgG

A

Chronic transmissible infection

189
Q

HBsAg
anti-HBc IgG
anti-HBe

A

Chronic non-transmissible infection

190
Q

anti-HBs
anti-HBc IgG
anti-HBe

A

Recovery

191
Q

anti-HBs

A

Immunized

192
Q

Function of HIV genes…
env
gag
pol

A

env = gp120 (attachment to host CD4+ T cell) and gp41 (fusion and entry)

gag = p24 (capsid) and p17 (matrix) proteins

pol = reverse transcriptase, protease, integrase

Note - env mutations responsible for avoidance of humoral response, and pol mutations responsible for resistance to HAART

193
Q

Host receptors used for HIV binding.

A 
CD4
Macrophage CCR5 (early) or T cell CXCR4 (late)

Homozygous CCR5 mutation instills immunity

194
Q

HIV diagnosis protocol.

A

ELISA (sensitive)
Western blot confirmation (specific)
Follow with viral load testing

Often falsely negative in first 1-2 months (require surface protein), and falsely positive in neonates (anti-gp120 crosses placenta)

AIDs if CD4 < 200 or HIV with AIDs-defining condition

195
Q

Time course of untreated HIV infection (CD4/viral load).

A

Primary infection (flu-like):
Normal, but declining CD4
High viral load

Clinical latency:
Slight initial recovery, but declining CD4
Stable viral load

Final phase/AIDs:
Rapid drop in CD4
Rapid increase in viral load

196
Q

Common infections in HIV patients with CD4 < 500.

A

Cryptosporidium
Bartonella (bacillary angiomatosis = PMN infiltration)
HHV-8 (kaposi = lymphocytic infiltration)
Candida (thrush = scrapable)
EBV (oral hairy leukoplakia = unscrapable)
HPV (anal SSC)

197
Q

Common infections in HIV patients with CD < 200.

A

Pneumocystis
HIV dementia
JC virus (PML)

198
Q

Common infections in HIV patients with CD < 100.

A 
Aspergillosis
Cryptococcosis
Histoplasmosis
Toxoplasmosis
Candida esophagitis
Mycobacterium avium
EBV (non-Hodgkin's, CNS lymphoma)
CMV (retinitis, esophagitis, colitis, pneumonitis, encephalitis)
199
Q

Mechanism of prion disease.

A

Transformation of a-helical PrPc (prion) to b-pleated PrPsc - resistant to proteases

200
Q

Common causes of pneumonia in children.

“Runts May Cough Sputum”

A

RSV
Mycoplasma
Chlamydia
S. pneumo

GBS in neonates

201
Q

Common causes of pneumonia in alcoholics.

A

Klebsiella

Anaerobes (Peptostrep, Fusobacterium, Bacteroides)

202
Q

Common causes of pneumonia in IVDU.

A

S. pneumo

S. aureus

203
Q

Common causes of meningitis in neonates.

A

GBS
E. coli
Listeria

204
Q

Common causes of meningitis in children and adults (< 6 y/o).

A 
S. pneumo
N. meningitidis
Enterovirus/Picorna (Echo, Coxsackie)
HSV-2 (HSV-1 = encephalitis)
HIB if unvaccinated

Ceftriaxone + Vancomycin (+ Acyclovir if HSV suspected)

205
Q

Common causes of meningitis in elderly (> 60 y/o).

A

S. pneumo
GNR
Listeria

Ceftriaxone + Vancomycin + Ampicillin

206
Q 
Meningitis with...
High opening pressure
High PMNs
High protein
Low glucose
A

Bacterial meningitis

207
Q 
Meningitis with...
High opening pressure
High lymphocytes
High protein
Low glucose
A

Fungal/TB meningitis

208
Q 
Meningitis with...
Normal or high opening pressure
High lymphocytes
Normal or high protein
Normal glucose
A

Viral meningitis

Note - HSV often presents with RBCs in CSF

209
Q 
Most common cause of osteomyelitis in...
Normal
SCD
Joint replacement
IVDU
Cat and dog bites
A 
S. aureus
Salmonella
S. epidermidis
Pseudomonas, Candida
Pasteurella
210
Q

Causes of UTI with…
Green metallic sheen on EMB (most common)
Sexually active women
Urease+, large mucoid capsule, nosocomial
Nosocomial and drug resistant
Urease+, swarming on agar, nosocomial, struvite stones
Blue-green pigment and fruity odor

A 
E. coli
E. coli > S. saprophyticus
Klebsiella
Serratia (red pigment), Enterococcus
Proteus
Pseudomonas
211
Q

Thick, white cottage cheese vaginal discharge
Inflammation

Pseudohyphae on wet mount (KOH prep)
pH normal (< 4.5)
A

CANDIDA VULVOVAGINITIS

Previous antibiotic use allows Candida to overgrow Lactobacillus

Treat with Clotrimazole cream or Fluconazole

212
Q

Neonate with…
Cataracts
Hearing loss
PDA (also pulmonary stenosis, septal defects)

A

CONGENITAL RUBELLA

213
Q 
Neonate with...
Seizures
Periventricular calcifications
Hearing loss
Hepatomegaly
A

CONGENITAL CYTOMEGALOVIRUS

214
Q

Oval-shaped vesicles on palms and soles

Vesicles and ulcers in oral mucosa

A

COXSACKIEVIRUS (HAND-FOOT-MOUTH)

Also causes...
Aseptic meningitis
Herpangina
Myocarditis
Pericarditis
215
Q

Painful genital ulcer with grey exudate/ragged borders

Inguinal adenopathy

A

CHANCROID

Haemophilus ducreyi

Treat with Azithromycin

216
Q

Causes of condylomata acuminta.

A

HPV-6 and HPV-11

217
Q 
Fever
Purulent cervical discharge
Adnexal tenderness
Cervical motion tenderness (chandelier sign)
Leukocytosis
Elevated ESR
A

PELVIC INFLAMMATORY DISEASE (ACUTE SALPINGITIS)

If outpatient treat with Ceftriaxone + Doxycycline (avoid if pregnant)

If inpatient treat with IV Cefotetan + Doxycycline or Clindamycin + Gentamicin

218
Q

Common causes of decubitus ulcers and surgical wounds.

A

S aureus

Anaerobes (Bacteroides, Fuso)

219
Q

Common causes of intravascular catheter infections.

A

S aureus
S epidermidis
Enterobacter

220
Q

Produce Hyaluronidase for spread through ground substance

A

Staph
GAS
C. Diff

221
Q

Progeny viruses contain unchanged parental genome but capsid proteins from other strains - phenotypic change in that generation only

A

PHENOTYPIC MIXING

Reassortment is when the progeny have altered parental genomes as well due to genomic exchange between two segmented viruses infecting the same cell

222
Q

Sexually active young woman…
Arthritis
Dermatitis
Tenosynovitis

A

DISSEMINATED GONORRHEA

223
Q

Painless serpigenous ulcerative lesions
No lymphadenopathy
Gram negative intracytoplasmic cysts

A

GRANULOMA INGUINALE (DONOVANOSIS)

Klebsiella Granulomatosis

224
Q

Flu-like illness
Severe myalgia
Retro-orbital pain
Rash

Transaminitis
Leukopenia
Thrombocytopenia
Positive tourniquet test

Transmitted by Aedes

A

DENGUE HEMORRHAGIC FEVER (FLAVIVIRUS)

Secondary infection with a different serotype - Primary mostly asymptomatic

225
Q

Bacteria in…
Cat bites
Dog bites
Human bites

A

Pasteurella, Bartonella Henselae (lymphangitis)
Pasteurella, Strep, S. aureus
Anaerobes, Strep, Eikenella

Treat with Augmentin

226
Q

Mechanism of acute liver failure in mushroom ingestion

A

Amatoxin - Inhibition of RNA Pol II

227
Q

Satellite phenomenon

A

when H influenzae type b grows on a culture around S. aureus because it produced V factor or NAD+

228
Q

cholera toxin mechanism

A

activates adenylate cyclase
increases Cl efflux and decreased Na reabs
mucin ejection from goblet cells

–> watery diarrhea

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