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
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)
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
4
Q
Medium containing Vancomycin (gram+), Trimethoprim (gram-), and Nystatin (fungi).
A
THAYER-MARTIN AGAR
Neisseria (gonorrhoeae, meningitidis)
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
6
Q
Medium for fungi growth.
A
Sabourad agar
7
Q
Common aerobic bacteria.
(“Nagging Pests Must Breathe”)
Note - Culture on reducing media
A
Nocardia
Pseudomonas
MycoBacterium
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
9
Q
Obligate intracellular bacteria.
“Really Close Cousins”
A
Rickettsia
Chlamydia
Coxiella
10
Q
Facultative intracellular bacteria.
“Some Nasty Bugs May Live FacultativeLY”
A
Salmonella Neisseria Brucella Mycobacterium Listeria Francisella Legionella Yersinia pestis
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
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
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)
14
Q
Biofilm producing bacteria.
“SErious Vall Producing Hombres”
A
S. epidermidis
Viridans strep (S. mutans, S. sanguinis)
Pseudomonas
HIB
15
Q
Bacteria producing IgA protease
A
S. pneumo
HIB
Neisseria
Note - Facilitates bacterial adherence to mucosal surface
16
Q
Bacteria producing TIII secretion system - direct delivery of toxins from certain Gram- bacteria.
A
Pseudomonas
Salmonella
Shigella
E. coli
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)
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
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
20
Q
Gram+ lab algorithm.
A
Bacilli:
Aerobic = Listeria, Bacillus, Corynebacterium
Anaerobic = Clostridium
Branching filaments:
Aerobic = Nocardia
Anaerobic = Actinomyces
Cocci (Aerobic):
Catalase test
21
Q
Gram+ cocci lab algorithm.
A
Catalase- = Streptococcus
Catalase+ = Staphyloccoccus
22
Q
Gram+ cocci, Catalase+ lab algorithm.
A
Coagulase+ = S. aureus (also b-hemolytic)
Coagulase-, Novobiocin sensitive = S. epidermidis
Coagulase-, Novobiocin resistant = S. saprophyticus
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)
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
25
Fever
Vomiting
Desquamating rash
Septic shock
Elevated AST and ALT
Elevated bilirubin
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).
26
Nonbloody diarrhea and emesis 2-6 hrs after eating meat, mayonnaise, or custard.
S. AUREUS FOOD POISONING
Pre-formed, heat stable, enterotoxin.
27
```
Child with...
Widespread painful erythroderma
Sparing of mucous membranes
Fluid filled blisters
Nikolsky sign
```
S. AUREUS SCALDED SKIN SYNDROME
Exfoliative toxin cleaves Desmoglein-1 (Desmosomes) in epidermis.
28
```
Gram+ cocci in clusters
Catalase+
Coagulase-
Novobiocin sensitive
Urease+
Biofilm producing
Skin flora
```
STAPHYLOCOCCUS EPIDERMIDIS
Infects prosthetics and IV catheters.
29
```
Gram+ cocci in clusters
Catalase+
Coagulase-
Novobiocin resistant
Urease+
Colonizes female genital tract and perineum
```
STAPHYLOCOCCUS SAPROPHYTICUS
2nd most common cause of uncomplicated UTI in young women (1st is e. coli).
30
```
Gram+ lancet diplococci
Catalase-
a-hemolytic
Optochin sensitive
Encapsulated
```
STREPTOCOCCUS PNEUMONIAE
31
S. pneumoniae is the most common cause of the following 4 diseases.
```
Pneumonia with rusty colored sputum
Sinusitis
Otitis media
Meningitis (most common in adults)
Sepsis in patients with SCD or asplenia
```
32
```
Gram+ cocci
Catalase-
a-hemolytic
Optochin resistant ("not afraid op-to-chin")
Biofilm producing
Synthesize Dextrans
```
VIRIDANS STREPTOCOCCI
```
Dental caries (S. mutans, S. mitis)
Brain abscesses
Endocarditis at damaged heart valves - dextrans bind fibrin clots (S. sanguinis)
```
33
```
Gram+ cocci
Catalase-
b-hemolytic
Bacitracin sensitive
PYR+
```
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)
34
```
Fever
Circumoral pallor
Strawberry tongue
Sore throat
Blanching, sandpaper-like rash
```
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
35
```
Intense pain out of proportion to rash
Edema
Discoloration
Crepitus
Dishwater like discharge
```
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
36
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)
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
37
```
Gram+ cocci in chains
Catalase-
b-hemolysis
Bacitracin resistant
PYR-
cAMP+
Colonizes vagina
```
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.
38
```
Gram+ cocci
Catalase-
y-hemolysis
No growth in NaCl
Colonizes gut
```
NONENTEROCOCCUS (S. BOVIS)
S. bovis type I (S. gallolyticus) causes bacteremia and subacute endocarditis.
Associated with colon cancer.
39
```
Gram+ cocci
Catalase-
y-hemolysis
Growth in NaCl
Colonize colon
```
ENTEROCOCCUS (E. FAECALIS)
Causes UTI, subacute IE, and wound infections - Following GI/GU procedures
All Penicillin G resistant - Some Vancomycin resistant (VRE)
40
Gram+ rod
Spore-forming (heat resistant)
Polypeptide D-glutamate (not polysaccharide) capsule
BACILLUS ANTHRACIS
```
Produces Anthrax (Edema) toxin...
Edema factor increases cAMP
Lethal factor (zinc-dependent protease) prevents protein kinase signaling
```
41
Painless papule surrounded by vesicles - Leads to a painless necrotic ulcer with black eschar.
Associated with livestock
CUTANEOUS ANTHRAX
Edema toxin mimics adenylate cyclase increasing cAMP.
42
Flu-like symptoms
```
Rapidly progressing to...
Fever
Pulmonary hemorrhage
Mediastinitis
Shock
```
PULMONARY ANTHRAX (WOOLSORTER'S DISEASE)
Edema toxin mimics adenylate cyclase increasing cAMP.
43
Gram+ rod
Spore-forming (heat resistant)
Associated with food poisoning
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.
44
Gram+ rod
Spore-forming (heat resistant)
Obligate anaerobe
CLOSTRIDIA
C. tetani
C. botulinum
C. perfringens
C. difficile
45
Spastic paralysis
Trismus (lockjaw)
Risus sardonicus (raised eyebrows, open grin)
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.
46
Diplopia, Dysphonia, Dysphagia
Descending flaccid paralysis
Anticholinergic signs
In infants presents as "floppy baby"
BOTULISM
C. botulinum heat-labile exotoxin cleaves SNARE - Blocks release of excitatory Ach at NMJ.
Note - Preformed toxin in canned foods, spores in honey
47
Myonecrosis of wound
Crepitus
Hemolysis (double zone on blood agar)
GAS GANGRENE
C. perfringens a-toxin (Lecithinase phospholipase).
48
Food poisoning (watery diarrhea) from undercooked, standing, or reheated meat.
C. PERFRINGENS
Heat-labile enterotoxin unlike B. cereus and S. aureus which are heat-stable.
49
Diarrhea following Clindamycin/Ampicillin (PPI increases risk)
Pseudomembranes (fibrin deposition) on colonoscopy
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
50
```
Gram+ club-shaped rod
Loeffler's medium
Methylene Blue - Metachromatic granules
Cystine-Tellurite agar - Black colonies
Elek test+ (toxin)
```
CORYNEBACTERIUM DIPHTHERIAE
Produces Diphtheria exotoxin
51
```
Pseudomembranous pharyngitis (gray-white)
Cervical lymphadenopathy
Myocarditis
Arrhythmias
Local neuropathy (soft palate paralysis)
```
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
52
Gram+ rod
Facultative anaerobe (avoids antibodies)
Facultative intracellular
Tumbling motility and rocket tails (actin polymerization)
Lives in unpasteurized dairy products and cold deli meat
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.
53
```
Gram+ branching filamentous
Weakly acid fast
Aerobic
Catalase+
Colonizes soil
```
NOCARDIA
Cutaneous involvement in immunocompetent
TB mimic in immunocompromised (normal PPD)
Brain abscess
Treat with Sulfonamides/TMP-SMX ("SNAP").
54
Gram+ branching filamentous
Anaerobe
Yellow "sulfur" granules (grossly)
Colonizes oropharynx, GU, GI
Note - Sulfur granules become blue with H/E
ACTINOMYCES
Causes...
Orofacial abscesses
PID with IUDs
Treat with Penicillin ("SNAP")
55
```
Acid fast (pink) rods (Gram+ but does not stain)
Facultative intracellular
```
MYCOBACTERIUM
M. tuberculosis
M avium
M leprae
M scrofulaceum (cervical lymphadenitis in children)
M marinum (hand infection in aquarium handlers)
56
```
Causes...
Productive or nonproductive cough
Hemoptysis
Fever
Night sweats
Weight loss
```
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
57
Disseminated non-TB disease in AIDs patients...
Constitutional signs
Diarrhea
Anemia
Hepatosplenomegaly
Elevated AlkP
Elevated LDH
Acid fast culture growing at 41 deg C
M. AVIUM
Prophylaxis with Azithromycin when CD4 < 50
Treat with (Clarithromycin or Azithromycin) + (Ethambutol or Rifabutin)
58
Infection of skin and superficial nerves resulting in a glove and stocking loss of sensation.
Likes cool temperatures and reservoir in Armadillos.
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
59
Gram- lab algorithm.
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
60
Gram- bacilli algorithm.
Lactose fermentation+
Fast = Klebsiella, E. coli
Slow = Serratia
Lactose fermentation-:
Oxidase test
61
Gram - bacilli, non-lactose fermenting algorithm.
Oxidase-:
H2S production on TSI agar = Salmonella, Proteus
No H2S production on TSI agar = Shigella, Yersinia
Odiaze+:
Pseudomonas
62
```
Gram- bean-shaped diplococci
Aerobic
Glucose fermentation+
Maltose-
Facultative intracellular (neutrophils)
Transmitted sexually or perinatally
```
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)
63
```
Gram- diplococci
Aerobic
Glucose fermentation+
Maltose+
Encapsulated
Facultative intracellular
Transmitted via respiratory or oral secretions
```
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
64
```
Gram- coccobacillus rod
Grown on chocolate agar (V/X)
Grown with S. aureus (V)
Encapsulated (typeable)
Biofilm producing
Transmitted by aerosols
```
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
65
Gram- coccobaccilus
Aerobic
Bordet agar
Lymphocytic infiltrate
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
66
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
LEGIONELLA PNEUMOPHILA
No gram staining due to unique polysaccharide chains on outer membrane
67
```
In a smoker or COPD patient...
Relative bradycardia
Unilateral lobar pneumonia
GI symptoms
CNS symptoms
Hyponatremia !!
Neutrophils with no bacteria
```
LEGIONNAIRES DISEASE (LEGIONELLA)
Pontiac fever is a mild-flu like form
Confirm with urine antigen test
Treat with Macrolide
68
```
Gram- rod
Aerobic
Lactose fermentation-
Oxidase+
Encapsulated
Biofilm producing
Blue-green pigment (Pyocyanin)
Grape-like odor
```
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)
```
69
Treatments for Pseudomonas.
| "CAMPFIRE"
```
Carbapenems
Aminoglycosides
Monobactams
Polymyxin
Fluoroquinolones
thIRd/fourth generation cephalosporins
Extended-spectrum penicillins (piperacillin, ticarcillin)
```
70
Rapidly progressive, necrotizing cutaneous lesion in immunocompromised patients.
ECTHYMA GANGRENOSUM
Pseudomonas bacteremia.
71
```
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)
```
E. COLI
Produces endotoxin
Virulence factors include Fimbriae/P-pili (cystitis, pyelonephritis) and K capsule (pneumonia, meningitis).
72
Strain of e. coli causing invasive dysentery (bloody diarrhea with pus).
EIEC
Invades GI mucosa and causes necrosis and inflammation.
73
Strain of e. coli causing traveler's diarrhea (watery diarrhea).
ETEC
Produces heat-labile/stable enterotoxin - no invasion or inflammation of GI mucosa.
74
Strain of e. coli causing pediatric diarrhea.
EPEC
Adheres to apical surface and flattens villi, preventing absorption.
75
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
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
76
Gram- rod
Lactose fermentation+
Encapsulated
Colonizes GI tract
KLEBSIELLA
Causes...
Lobar antimicrobial aspiration pneumonia with mucoid currant jelly sputum (diabetes, alcoholics)
Nosocomial UTIs
Abscesses (lungs, liver)
77
Gram- comma-shaped rod
Oxidase+
Grows in 42 deg C
Polar flagella
Transmitted fecal-oral
CAMPYLOBACTER JEJUNI
Causes...
Bloody diarrhea
GBS
Reactive arthritis
78
```
Gram- rod
Lactose fermentation-
Oxidase-
H2S production on TSI agar
Facultative intracellular
Flagella (hematogenous dissemination) with antigenic variation
```
SALMONELLA
Requires high inoculum - primarily monocytic response if s. typhi (s. spp. PMNs if disseminated)
Produces endotoxin
S. typhi produces Vi capsule
79
```
Gram- rod
Lactose fermentation-
Oxidase-
No H2S production on TSI agar
No flagella (cell to cell spread only)
```
SHIGELLA
Requires low inoculum - primarily neutrophil infiltration response
Produces endotoxin
Produces Shiga toxin
80
```
Initial constipation
Diarrhea (monocytic infiltrate)
Rose spots on abdomen
Abdominal pain
Hepatosplenomegaly
Fever
Relative bradycardia
```
Transmitted by fecal-oral
TYPHOID FEVER (SALMONELLA TYPHI)
Carrier state with gallbladder colonization
Treat with...
Ceftriaxone or Fluoroquinolone (prolongs fecal excretion)
81
Causes self-limiting gastroenteritis (no antibiotics indicated) - Reservoirs in turtles, poultry, and eggs.
SALMONELLA SPP.
Taken up by M cells and then infects and survives within macrophages
Note - Can cause mesenteric adenitis unlike Shigella
82
Bloody diarrhea with pus (dysentery)
Transmitted by fingers/flies in food/feces
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)
83
Gram- comma-shaped rod
Oxidase+
Grows in alkaline media
Unipolar flagella
VIBRIO CHOLERAE
Toxin over-activates adenylate cyclase (permanently activates Gs) increasing cAMP - Increased Cl-/H2O secretion (rice-water diarrhea)
Treat with oral rehydration
84
```
Gram- rod
Lactose fermentation-
Oxidase-
No H2S production on TSI agar
Facultative intracellular
Transmitted by farm animals
```
YERSINIA ENTEROCOLITICA
Causes...
Acute bloody diarrhea
Pseudo-appendicitis (mesenteric adenitis, terminal ileitis)
Yersinia pestis causes plague
85
```
Gram- comma-shaped rod
Oxidase+
Catalase+
Urease+
Flagellum
```
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
86
Spiral-shaped
Axial filament
Transmitted by water contaminated by animal urine
LEPTOSPIRA INTERROGANS (SPIROCHETE)
87
```
Surfer or patient in the tropics with...
Flu-like symptoms
Myalgia (calves)
Jaundice
Photophobia
Conjunctival suffusion (erythema without exudate)
```
LEPTOSPIROSIS
Weil disease is a severe form (icterohemorrhagic) that also presents with azotemia (kidney dysfunction), hemorrhage, and anemia.
88
Spiral-shaped
Giemsa stain
Axial filament
Transmitted by Ixodes
BORRELIA BURGDORFERI (SPIROCHETE)
89
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
LYME DISEASE
Treat with Doxycycline or Ceftriaxone
90
Spiral-shaped
Dark-field microscopy
Axial filament
TREPONEMA PALLIDUM (SPIROCHETE)
91
Painless chancre
PRIMARY SYPHILIS
Dark-field microscopy on fluid from chancre, or VDRL.
92
Fever
Maculopapular rash (including palms/soles)
Condylomata lata (painless wart-like white lesions)
Lymphadenopathy
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
```
Gummas (chronic granulomas)
Aortitis (vaso vasorum destruction)
Argyll-Robertson pupil (accommodates only)
General paresis
Tabes dorsalis
Broad-based ataxia
Romberg sign
Charcot joint
```
TERTIARY SYPHILIS
For neurosyphilis LP with VDRL, FTA-ABS, PCR
94
Often stillbirth or hydrops fetalis
```
If survives...
Saddle nose
Short maxilla
Notched teeth
Mulberry molars
Saber shins
CN VIII deficits
```
CONGENITAL SYPHILIS
Treat mother before first trimester
95
False-positives on VDRL.
| "VDRL"
Viral infections (EBV, hepatitis)
Drugs
Rheumatic fever
Lupus/Leprosy
96
Flu-like syndrome after treating syphilis.
JARISCH-HERXHEIMER REACTION
Killer bacteria release toxins.
97
Gray vaginal discharge
Fishy smell
No inflammation
Nonpainful
```
Clue cells (vaginal epithelium covered with bacteria)
pH > 4.5
```
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
Rash spreading from wrists/ankles to palms/soles
Headache
Fever
Vector is tick
Giemsa stain
ROCKY MOUNTAIN SPOTTED FEVER
Rickettsia rickettsii
Treat with Doxycycline
99
Central rash spreading out - spares palms and soles
Vector is lice
TYPHUS
Rickettsia typhus/prowazekii
Treat with Doxycycline
100
Flu-like symptoms
Monocytes with morulae (mulberry-like cytoplasmic inclusions)
Vector is tick
EHRLICHIOSIS
Treat with Doxycycline
101
Flu-like symptoms
Granulocytes with morulae (mulberry-like cytoplasmic inclusions)
Vector is tick
ANAPLASMOSIS
Treat with Doxycycline
102
```
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
Q FEVER
Coxiella burnetti - Obligate intracellular parasite requires cell media to grow
Treat with Doxycycline
103
Cytoplasmic inclusions seen on Giemsa or fluorescent antibody stain.
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
```
Causes...
Reactive arthritis (Reiter syndrome)
Follicular conjunctivitis
Nongonococcal urethritis/PID
Neonatal pneumonia
Neonatal conjunctivitis
```
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
Small, painless ulcers on genitals
| Swollen, painful inguinal lymph nodes (ulcerating)
LYMPHOGRANULOMA VENEREUM
Treat with Doxycycline.
106
```
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
MYCOPLASMA ATYPICAL PNEUMONIA
Treat with Macrolides, Doxycycline, or Fluoroquinolones
107
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)
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
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
BLASTOMYCOSIS
Forms granulomatous nodules and causes...
Pneumonia
Disseminate to skin/bone
Fluconazole or Itraconazole if local
Amphotericin B if systemic
109
Mold with hyphae in cold
Thick-walled spherules in heat
Spherules filled with endospores - much larger than RBC
Common in SW US dust
COCCIDIOMYCOSIS
Causes...
Flu-like illness
Dissemination to skin (erythema nodosum), bone (arthralgias), and meninges
Fluconazole or Itraconazole if local
Amphotericin B if systemic
110
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
PARACOCCIDIOIDOMYCOSIS
Chronic cutaneous or mucocutaneous ulcers - can progress to lung and lymph nodes
111
Infections caused by dermatophytes - Microsporum, Trichophyton, Epidermophyton
Branching septate hyphae on KOH with blue fungal stain
```
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
Well demarcated hyper or hypopigmented salmon-colored lesions on the trunk
"Spaghetti and Meatballs" appearance on KOH
TINEA (PITYRIASIS) VERSICOLOR
Malassezia spp. (yeast) causes degradation of lipids producing acids that damage melanocytes.
Treat with Ketoconazole with Selenium Sulfide lotion
113
White dimorphic yeast
Pseudohyphae with budding/blastoconidia when cold
Germ tubes when warm
Note - Colonizes oral cavity (sputum contaminant)
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
Treatment for candidiasis (vaginal, oral/esophageal, systemic).
```
Vaginal = Topical Azole
Oral/Esophageal = Nystatin, Fluconazole, or Caspofungin
Systemic = Fluconazole, Caspofungin, or Ampho B
```
115
Fungal hyphae
Hyphae branching at acute angles
Conidia (radiating flower-like chains) at end of conidiophore
ASPERGILLUS FUMIGATUS
116
```
Immunocompromised patient with...
Fever
Chest pain
Cough
Dyspnea
Hemoptysis
```
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
Hypersensitivity response in patients with asthma and cystic fibrosis - Causes bronchiectasis and eosinophilia.
ALLERGIC BRONCHOPULMONARY ASPERGILLOSIS (ABPA)
Diagnose with serologic testing and skin hypersensitivity
118
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
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
Broad ribbon-like hyphae
No septae
Right angle branching
MUCOR/RHIZOPUS SPP
120
```
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
MUCORMYCOSIS
Proliferate in blood vessel walls and penetrate cribriform plate to enter brain
Surgical debridement with IV AmphoB
121
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
PNEUMOCYSTIS PNEUMONIA
Pneumocystis jirovecii (yeast-like fungus)
Prevent with TMP-SMX when CD4 < 200. Treat with TMP-SMX or Pentamidine
122
Local pustule or ulcer with nodules along draining lymphatics (ascending lymphangitis) - may disseminate if immunocompromised.
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
Protozoa causing...
Bloating
Flatulence
Foul-smelling fatty diarrhea
Villous atrophy with crypt hyperplasia
Cysts in water
GIARDIASIS
Giardia lamblia - Diagnose with multinucleated ellipsoid cysts in stool
Treat with Metronidazole
124
```
Protozoa causing...
Bloody diarrhea (dysentery)
RUQ pain
Liver abscess (anchovy paste exudate)
Flask shaped ulcers
```
Cysts in water
AMEBIASIS
Entamoeba histolytica - Diagnose with serology, trophocytes with engulfed RBCs in cytoplasm, or multinucleated cysts in stool
Treat with Metronidazole or Iodoquinol (asymptomatic)
125
Protozoa causing severe diarrhea in HIV patient
Non-ulcerative inflammation
Basophilic clusters on mucosa
Oocytes in water
CRYPTOSPORIDIUM
Diagnose with oocyst on acid-fast stain
Prevent by filtering water
Treat with Nitazoxanide (immunocompetent only)
126
Protozoa causing...
In neonates triad of...
Chorioretinitis
Hydrocephalus
Intracranial calcifications
In AIDs patients...
Ring-enhancing lesions on MRI
TOXOPLASMOSIS
Toxoplasma gondii - cysts in meat, oocyte in cat feces
Diagnose with serology, or tachyzoite on biopsy
Treat with TMP-SMX/Pyrimethamine
127
Protozoa causing rapidly fatal meningoencephalitis
Transmitted by fresh-water and enters CNS via cribriform plate
NAEGLERIA FOWLERI
Diagnose with amoebas in LP
Treat with Ampho B
128
```
Protozoa causing...
Enlarged lymph nodes
Recurring fever (antigenic variation)
Somnolence
Coma
```
Transmitted by the Tsetse fly
Giemsa stain
AFRICAN SLEEPING SICKNESS
Trypanosoma brucei (antigenic variation) - diagnose with trypomastigotes in blood smear
Suramin for fever
Melarsoprol if CNS penetration (somnolence)
129
```
Protozoa causing...
Fever
Headache
Anemia
Splenomegaly
```
Transmitted by Anopheles
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
```
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)
BABESIOSIS
Treat with Atovaquone + Azithromycin
Note - If severe (e.g. asplenic patients) may present with ARDS, DIC
131
Protozoa causing...
Acutely unilateral periorbital swelling
Dilated cardiomyopathy with apical atrophy
Megacolon
Megaesophagus
Transmitted by Reduviid bug
Giemsa stain
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
Protozoa causing...
Spiking fevers
Hepatosplenomegaly
Pancytopenia
Transmitted by sandfly
VISCERAL LEISHMANIASIS
Cutaneous form presents with only skin ulcers
Leishmania donovani - diagnose with macrophages containing amastigotes
Treat with Sodium Stibogluconate or AmphoB
133
```
Protozoa causing...
Frothy, green vaginal discharge
Foul smelling
Inflammation (strawberry cervix)
Itching and burning
```
pH > 4.5
Motile trophozoites on wet mount
TRICHOMONAS VAGINITIS
Treat with Metronidazole - also treat partners (STI)
134
Intestinal nematode infection causing anal pruritus
Transmission is fecal-oral
PINWORMS
Enterobius vermicularis - diagnosed by eggs on tape test
Treat with Bendazoles (Pyrantel Pamoate if pregnant)
135
Intestinal nematode infection with obstruction of ileocecal valve
Transmission is fecal-oral
GIANT ROUNDWORM
Ascaris lumbricoides - diagnosed by eggs in feces
Treat with Bendazoles
136
Intestinal nematode infection causing vomiting, diarrhea, and epigastric pain (mimics peptic ulcer) - may result in autoinfection and shock
Transmission is cutaneous
STRONGYLOIDES
Diagnosed with rhabditiform (non-infectious) in the stool
Treat with Ivermectin
137
Intestinal nematode infection causing...
Microcytic anemia
Cutaneous larva migrans (pruritic, serpiginous rash)
Transmission is cutaneous
HOOKWORM
Ancylostoma duodenale or Necator americanus
Treat with Pyrantel pamoate or Bendazoles
138
```
Intestinal nematode infection causing...
Fever
N/V
Periorbital edema
Myalgia
```
Transmission is fecal-oral and by undercooked pork
TRICHINOSIS
Trichinella spiralis
Treat with Bendazoles
139
Nematode causing...
Myocarditis
Seizures
Liver damage
Transmission is fecal-oral
VISCERAL LARVA MIGRANS
Toxocara canis - migrate to blood through intestinal wall
Treat with Bendazoles
140
Nematode causing...
Black skin nodules
Loss of elastic fibers
Blindness
Transmission by female blackfly
RIVER BLINDNESS
Onchocerca volvulus
Treat with Ivermectin
141
Nematode causing...
Swelling in skin
Worm in conjunctiva
Transmission by horse/deer fly
LOA LOA
Treat with Diethylcarbamazine
142
Nematode invading lymph nodes and causes inflammation, which blocks lymphatic vessels and eventually causes elephantiasis
Transmission by female mosquito
WUCHERERIA BANCROFTI
Treat with Diethylcarbamazine
143
Cestode causing...
Intestinal tapeworm
Cysticercosis
Transmission by larvae in undercooked pork
Transmission by eggs from human feces
TAENIA SOLIUM
Treat with Praziquantel
144
Cestode causing megaloblastic anemia (vit B12 deficiency)
Transmission by larvae in raw freshwater fish
DIPHYLLOBOTHRIUM LATUM
Treat with Praziquantel
145
Cestode causing hydatid cysts in liver
Eggshell calcifications on microscopy
Transmission by eggs from dog feces, lives in sheep
ECHINOCOCCUS GRANULOSUS
Treat with Albendazole - Inject cyst with Ethanol/NaCl before removal to prevent Anaphylaxis
146
```
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
SCHISTOSOMA
Note - Periportal pipestem fibrosis is pathognomonic
Treat with Praziquantel
147
Trematode causing biliary tract inflammation leading to pigmented gallstones and cholangiocarcinoma.
Transmission is by undercooked fish
CLONORCHIS SINENSIS
Treat with Praziquantel
148
Mites that burrow into the stratum corneum and cause serpiginous burrows in webspace of hands and feet, and intense pruritus.
SARCOPTES SCABIEI
Treat with Permethrin cream - also treat close contacts
149
Blood sucking insects causing intense pruritus, pink macules, and papules in intertriginous regions.
PEDICULUS HUMANUS/PHTHIRUS PUBIS
150
Live attenuated vaccines - Humoral and cell-mediated immunity (no booster) but avoid in immunocompromised patients.
```
MMR (give to HIV if not AIDs)
Chickenpox
Influenza (intranasal)
Sabin polio (oral)
Rotavirus
Smallpox
Yellow fever
BCG
```
151
Killed (inactivated) vaccines - Humoral immunity only
Rabies
Influenza (IM)
Salk polio (IM)
HAV
Note - Tetanus/Diptheria/Botulism are toxoid vaccines
152
Subunit vaccines.
```
HBV
HPV
Pertussis
HiB
PCV
Meningococcal
```
153
DNA viruses
| "HHAPPPPy"
```
Hepadna (partially ds, circular)
Herpes
Adeno
Pox
Parvo (ssDNA, "parvo a virus")
Papilloma (circular)
Polyoma (circular)
```
154
Flesh-colored papule with central umbilication.
MOLLUSCUM CONTAGIOSUM
Poxvirus - Only DNA virus with own DNA-dependent RNA polymerase thus only DNA virus replicating outside of the nucleus
155
```
Year-round virus causing...
Febrile pharyngitis
Acute hemorrhagic cystitis
Pneumonia
Conjunctivitis
Watery diarrhea
```
ADENOVIRUS
156
Virus causing...
Progressive multifocal leukoencephalopathy (PML)
BK virus (targets kidneys) in transplant patients
POLYOMAVIRUS
157
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)
PARVOVIRUS
Note - Infects erythrocyte progenitors in bone marrow via blood group P antigen
158
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
HSV-1
Most common cause of sporadic encephalitis - viral meningitis more common with HSV-2
Valacyclovir (prodrug - better oral availability)
159
Virus causing...
Varicella-Zoster
Encephalitis
Pneumonia
Transmitted by respiratory secretions
Note - As part of TORCH causes limb hypoplasia, cutaneous scarring, chorioretinitis, and cataracts
VARICELLA-ZOSTER (HHV-3)
Latent in dorsal root and trigeminal ganglion - HSV-2 latent in sacral ganglion
Famciclovir
160
```
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
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
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
CYTOMEGALOVIRUS (HHV-5)
Latent in mononuclear cells, basophilic owl eye inclusions on smear
Note - prophylaxis with Valganciclovir in transplant patients
162
Virus causing...
High fever with febrile seizures for several days
Followed by diffuse macular rash starting on the trunk
Transmitted by oral secretions
HHV-6/7
Roseola infantum/exanthem subitum - Infects lymphocytes
163
Virus causing...
| Dark/violaceous plaques or nodules (vascular proliferations) in an HIV/AIDS or transplant patient
HHV-8
Kaposi sarcoma (endothelial cells)
164
Detection of multinucleated giant cells caused by HHVs.
TZANCK SMEAR
For HSV-1, HSV-2, and VZV
165
Enveloped DNA viruses - others are infective even when naked.
("HHaPpppy")
Herpes
Hepadna
Pox
166
+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")
```
Retro
Toga
Flavi
Corona (common cold, SARS, MERS)
Hepe
Calici (Noro)
Picorna
```
167
Segmented viruses.
| "BOAR"
Bunyavirus
Orthomyxovirus
Arenavirus
Reovirus
168
Picornaviruses.
| "PERCH"
```
Polio
Echo - Aseptic meningitis
Rhino - Common cold (uniquely not enterovirus)
Coxsackie
HAV
```
169
High fever
Black vomitus
Jaundice
Transmitted by Aedes mosquito
YELLOW FEVER (FLAVIVIRUS/ARBOVIRUS)
Eosinophilic apoptotic globules on liver biopsy
Other flavivirus include Dengue
170
Causes acute watery diarrhea during the winter - Incidence reduced due to vaccination
ROTAVIRUS (REOVIRUS)
Only dsRNA virus
Villous destruction with atrophy leads to decreased absorption of Na and renal K wasting
171
Viral cause of influenza - at risk for fatal bacterial superinfection (S. aureus, S. pneumoniae, HIB).
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
```
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
```
RUBELLA (TOGAVIRUS)
173
```
Seal-like barking cough
Inspiratory stridor
Pulsus paradoxus (>10 drop in SBP on inspiration)
```
Steeple sign on XR
CROUP/PARAINFLUENZA (PARAMYXOVIRUS)
Surface F protein causes respiratory epithelial cells to fuse and form multinucleated cells
174
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)
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
```
Virus causing...
Parotitis
Orchitis
Aseptic meningitis
Pancreatitis
```
May result in sterility
MUMPS (PARAMYXOVIRUS)
Surface F protein causes respiratory epithelial cells to fuse and form multinucleated cells
176
Virus causing bronchiolitis/pneumonia in babies - predominant during winter
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
Initially fever and malaise weeks to months after bite (bat, raccoon, skunk)
Later agitation, photophobia, hydrophobia, and hypersalivation
Eventually paralysis, coma, and death
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
```
Virus causing...
Abrupt onset high fever
Diarrhea
N/V
Myalgia
```
May progress to DIC, diffuse hemorrhage, and shock
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
Virus causing hemorrhagic fever and pneumonia.
HANTAVIRUS (BUNYAVIRUS)
180
Naked RNA viruses.
"CPR to a naked HIPpie"
Calici (Noro)
Picorna (PERCH)
Reo (Rota)
Hepe (HEV)
181
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
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
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)
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
```
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
HCV (FLAVI)
Lack of 3'-5' exonuclease proofreading increases antigenic variation
Note - May result in cryoglobulinemia vasculitis (arthralgia, myalgia, purpura)
184
Enveloped
Parenteral, sexual, perinatal transmission
Superinfection with HBV worsens prognosis
Requires presence of HBV to make viral envelope
HDV (DELTA)
185
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
HEV (HEPE)
186
HBsAg
HBeAg
anti-HBc IgM
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
anti-HBc IgM
| anti-HBe
Window period
188
HBsAg
HBeAg
anti-HBc IgG
Chronic transmissible infection
189
HBsAg
anti-HBc IgG
anti-HBe
Chronic non-transmissible infection
190
anti-HBs
anti-HBc IgG
anti-HBe
Recovery
191
anti-HBs
Immunized
192
Function of HIV genes...
env
gag
pol
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
Host receptors used for HIV binding.
```
CD4
Macrophage CCR5 (early) or T cell CXCR4 (late)
```
Homozygous CCR5 mutation instills immunity
194
HIV diagnosis protocol.
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
Time course of untreated HIV infection (CD4/viral load).
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
Common infections in HIV patients with CD4 < 500.
Cryptosporidium
Bartonella (bacillary angiomatosis = PMN infiltration)
HHV-8 (kaposi = lymphocytic infiltration)
Candida (thrush = scrapable)
EBV (oral hairy leukoplakia = unscrapable)
HPV (anal SSC)
197
Common infections in HIV patients with CD < 200.
Pneumocystis
HIV dementia
JC virus (PML)
198
Common infections in HIV patients with CD < 100.
```
Aspergillosis
Cryptococcosis
Histoplasmosis
Toxoplasmosis
Candida esophagitis
Mycobacterium avium
EBV (non-Hodgkin's, CNS lymphoma)
CMV (retinitis, esophagitis, colitis, pneumonitis, encephalitis)
```
199
Mechanism of prion disease.
Transformation of a-helical PrPc (prion) to b-pleated PrPsc - resistant to proteases
200
Common causes of pneumonia in children.
| "Runts May Cough Sputum"
RSV
Mycoplasma
Chlamydia
S. pneumo
GBS in neonates
201
Common causes of pneumonia in alcoholics.
Klebsiella
| Anaerobes (Peptostrep, Fusobacterium, Bacteroides)
202
Common causes of pneumonia in IVDU.
S. pneumo
| S. aureus
203
Common causes of meningitis in neonates.
GBS
E. coli
Listeria
204
Common causes of meningitis in children and adults (< 6 y/o).
```
S. pneumo
N. meningitidis
Enterovirus/Picorna (Echo, Coxsackie)
HSV-2 (HSV-1 = encephalitis)
HIB if unvaccinated
```
Ceftriaxone + Vancomycin (+ Acyclovir if HSV suspected)
205
Common causes of meningitis in elderly (> 60 y/o).
S. pneumo
GNR
Listeria
Ceftriaxone + Vancomycin + Ampicillin
206
```
Meningitis with...
High opening pressure
High PMNs
High protein
Low glucose
```
Bacterial meningitis
207
```
Meningitis with...
High opening pressure
High lymphocytes
High protein
Low glucose
```
Fungal/TB meningitis
208
```
Meningitis with...
Normal or high opening pressure
High lymphocytes
Normal or high protein
Normal glucose
```
Viral meningitis
Note - HSV often presents with RBCs in CSF
209
```
Most common cause of osteomyelitis in...
Normal
SCD
Joint replacement
IVDU
Cat and dog bites
```
```
S. aureus
Salmonella
S. epidermidis
Pseudomonas, Candida
Pasteurella
```
210
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
```
E. coli
E. coli > S. saprophyticus
Klebsiella
Serratia (red pigment), Enterococcus
Proteus
Pseudomonas
```
211
Thick, white cottage cheese vaginal discharge
Inflammation
```
Pseudohyphae on wet mount (KOH prep)
pH normal (< 4.5)
```
CANDIDA VULVOVAGINITIS
Previous antibiotic use allows Candida to overgrow Lactobacillus
Treat with Clotrimazole cream or Fluconazole
212
Neonate with...
Cataracts
Hearing loss
PDA (also pulmonary stenosis, septal defects)
CONGENITAL RUBELLA
213
```
Neonate with...
Seizures
Periventricular calcifications
Hearing loss
Hepatomegaly
```
CONGENITAL CYTOMEGALOVIRUS
214
Oval-shaped vesicles on palms and soles
| Vesicles and ulcers in oral mucosa
COXSACKIEVIRUS (HAND-FOOT-MOUTH)
```
Also causes...
Aseptic meningitis
Herpangina
Myocarditis
Pericarditis
```
215
Painful genital ulcer with grey exudate/ragged borders
| Inguinal adenopathy
CHANCROID
Haemophilus ducreyi
Treat with Azithromycin
216
Causes of condylomata acuminta.
HPV-6 and HPV-11
217
```
Fever
Purulent cervical discharge
Adnexal tenderness
Cervical motion tenderness (chandelier sign)
Leukocytosis
Elevated ESR
```
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
Common causes of decubitus ulcers and surgical wounds.
S aureus
| Anaerobes (Bacteroides, Fuso)
219
Common causes of intravascular catheter infections.
S aureus
S epidermidis
Enterobacter
220
Produce Hyaluronidase for spread through ground substance
Staph
GAS
C. Diff
221
Progeny viruses contain unchanged parental genome but capsid proteins from other strains - phenotypic change in that generation only
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
Sexually active young woman...
Arthritis
Dermatitis
Tenosynovitis
DISSEMINATED GONORRHEA
223
Painless serpigenous ulcerative lesions
No lymphadenopathy
Gram negative intracytoplasmic cysts
GRANULOMA INGUINALE (DONOVANOSIS)
Klebsiella Granulomatosis
224
Flu-like illness
Severe myalgia
Retro-orbital pain
Rash
Transaminitis
Leukopenia
Thrombocytopenia
Positive tourniquet test
Transmitted by Aedes
DENGUE HEMORRHAGIC FEVER (FLAVIVIRUS)
Secondary infection with a different serotype - Primary mostly asymptomatic
225
Bacteria in...
Cat bites
Dog bites
Human bites
Pasteurella, Bartonella Henselae (lymphangitis)
Pasteurella, Strep, S. aureus
Anaerobes, Strep, Eikenella
Treat with Augmentin
226
Mechanism of acute liver failure in mushroom ingestion
Amatoxin - Inhibition of RNA Pol II
227
Satellite phenomenon
when H influenzae type b grows on a culture around S. aureus because it produced V factor or NAD+
228
cholera toxin mechanism
activates adenylate cyclase
increases Cl efflux and decreased Na reabs
mucin ejection from goblet cells
--> watery diarrhea
