My Micro Part 1, USMLE Flashcards
Bacterial structure: Rigid support
Peptidoglycan
Bacterial structure: Major surface antigens (2)
1) Cell wall
2) Outer membrane (G-)
Bacterial structure: Protects against osmotic pressure
Peptidoglycan
Bacterial structure: Site of oxidative and transport enzymes
Plasma membrane
Bacterial structure: Site of endotoxin
Outer membrane (G-)
Bacterial structure: Space between the cytoplasmic membrane and outer membrane in G-
Periplasm
Bacterial structure: Site of lipopolysaccharide
Outer membrane (G-); aka endotoxin
Bacterial structure: Mediate adherence of bacteria to cell surface
Pilus/fimbria
Bacterial structure: Motility
Flagellum
Bacterial structure: Resistant to dehydration, heat, and chemicals
Spore
Bacterial structure: Forms attachment between 2 bacteria during conjugation
Sex pilus
Bacterial structure: Contains genes for antibiotic resistance, enzymes, and toxins
Plasmid
Bacterial structure: Adherence to surfaces, especially foreign surfaces (e.g. indwelling catheters)
Glycocalyx
Bacterial structure: Sugar backbone with peptide side chains cross- linked by transpeptidase
Peptidoglycan
Bacterial structure: Lipoteichoic acid
Cell wall
Bacterial structure: Lipid A
Outer membrane (G-)
Bacterial structure: O polysaccharide
Outer membrane (G-)
Bacterial structure: Phospholipid bilayer
Plasma membrane
Bacterial structure: Contains hydrolytic enzymes, including beta lactamases
Periplasm
Bacterial structure: Component of pilus/fimbria
Glycoprotein
Bacterial structure: Component of flagellum
Protein
Bacterial structure: Components of spore
1) Dipicolinic acid
2) Peptidoglycan
Bacterial structure: Keratin-like coat
Spore
Bacterial structure: DNA
Plasmid
Bacterial structure: Component of capsule
Organized discrete polysaccharide layer EXCEPT B. anthracis
Subunits of bacterial ribosome
30S and 50S
Substances induced by exposure to major surface antigens
TNF and IL-1
Component of cell wall that induces TNF and IL-1
Lipoteichoic acid
Component of outer membrane (G-) that induces TNF and IL-1
Lipid A
Antigen of outer membrane (G-)
O polysaccharide
Component of capsule of B. anthracis
D-glutamate (a polypeptide, not polysaccharide)
Bacterial structure: Composed of loose network of polysacharides
Glycocalyx
Bacterial structure: Unique to G+
Lipoteichoic acid
Bacterial structure: Unique to G-
1) Outer membrane
2) Porin on outer membrane
3) Periplasmic space
G+ rods
1) Bacillus
2) Clostridium
3) Corynebacterium
4) Gardnerella (Gram variable)
5) Lactobacillus
6) Listeria
7) Mycobacterium
8) Propionibacterium
G- zoonotic rods
- ELLAs
1) Batonella
2) Brucella
3) Francisella
4) Pasteurella
Branching filamentous G+ bacteria
1) Actinomyces
2) Nocardia
Weakly acid fast bacteria
Nocardia
Bacteria: Giemsa
Certain Bugs Really Try my Patience
1) Chlamydia (pleomorphic)
2) Borrelia (spirochete)
3) Rickettsia (pleomorphic)
4) Trypanosomes
5) Plasmodium
Bacteria without cell wall
1) Mycoplasma
2) Ureaplasma
Component of membrane of mycoplasma and ureaplasma
Sterols
Component of mycobacterial cell wall responsible for acid fast staining
Mycolic acids
Component of acid fast staining that stains my colic acid
Carbolfuchsin
Means of identification/staining of T. pallidum
1) Dark-field microscopy
2) Fluorescent antibody staining
Bacteria: Lacks classic peptidoglycan because of low muramic acid, rendering beta lactam antibiotics less effective
Chlamydia
Bacteria: PAS
Tropheryma whipplei (Whipple disease)
Bacteria: Ziehl-Neelsen
1) Mycobacteria
2) Nocardia
3) Cryptosporidium oocysts (protozoa)
Bacteria: India ink
Cryptococcus neoformans
Bacteria: Silver stain
1) Fungi (P. jiroveci)
2) Legionella
3) H. pylori
Substance stained by PAS
[PASs the sugar]
Glycogen and mucopolysaccharides
Alternative to Ziehl-Neelsen staining
Auramine-rhodamine stain (inexpensive but less specific)
Alternative to india ink
Mucicarmine
Mucicarmine stains the polysaccharide capsule of C. neoformans what color?
Red
Culture medium/media: H. influenzae
Chocolate agar
Culture medium/media: N. gonorrhea/N. meningitidis
Thayer-Martin
Culture medium/media: B. pertussis
1) Bordet-Gengou
2) Regan-Lowe
Culture medium/media: C. diphtheriae
1) Tellurite agar
2) Loffler medium
Culture medium/media: M. tuberculosis
Lowenstein-Jensen
Culture medium/media: M. pneumoniae
Eaton agar
Culture medium/media: E. coli
EMB
Culture medium/media: Legionella
Charcoal yeast extract agar buffered with cysteine and iron
Culture medium/media: Fungi
Sabouraud agar
Media content: CAP (esp. for H. influenzae)
1) Factor V (NAD)
2) Factor X (hematin)
Media content: Thayer-Martin, inhibits G+
Vancomycin
Media content: Thayer-Martin, inhibits G- except Neisseria
Colistin
Media content: Thayer-Martin, inhibits fungi
Nystatin
Media content: Thayer-Martin
[Very Typically Cultures Neisseria]
1) Vancomycin
2) Trimethoprim
3) Colistin
4) Nystatin
Media content: Bordet-Gengou
Potato
Media content: Regan-Lowe
1) Charcoal
2) Blood
3) Antibiotic
Media content: Eaton agar (esp. for M. pneumoniae)
Cholesterol
Use an O2-dependent system to generate ATP
Aerobes
Aerobes
[Nagging Pests MustBreathe]
1) Nocardia
2) Pseudomonas
3) MycoBacterium tuberculosis
Triggers for reactivation of M. tuberculosis
1) Immunocompromise
2) TNF-alpha inhibitor use
Generally foul smelling (short-chain fatty acids), are difficult to culture, and produce gas in tissue (CO2 and H2); normal flora in GIT
Anaerobes
Anaerobes
[Frankly Can’t Breathe Air]
1) Fusobacterium
2) Clostridium
3) Bacteroides
4) Actinomyces
Anaerobes lack these enzymes, making them susceptible to oxidative damage
1) Catalase
2) Superoxide dismutase
Antibiotics that are ineffective against anaerobes because they require O2 to enter bacterial cell
AminO2glycosides
Rely on host ATP for survival
Obligate intracellular bacteria
Obligate intracellular bacteria
[Really CHilly and COld]
1) Rickettsia
2) Chlamydia
3) Coxiella
Facultative intracellular bacteria
[Some Nasty Bugs May Live FacultativeLY]
1) Salmonella
2) Neisseria
3) Brucella
4) Mycobacteria
5) Legionella
6) Francisella
7) Listeria
8) Yersinia pestis
Significance of spleen in ridding of encapsulated bacteria
Opsonized bacteria are cleared by spleen
Vaccines given for asplenics
1) S. pneumoniae
2) H. influenzae
3) N. meningitidis
T/F A polysaccharide antigen (capsule) alone can be presented to T cells, promoting T cell activation and subsequent class switching
F, conjugated to a carrier protein, enhancing immunogenicity
Pneumococcal polysaccharide vaccine with no conjugated protein
Pneumovax
Urease-positive organisms
[CHuck norris hates PUNKSS]
1) Cryptococcus
2) H. pylori
3) Proteus
4) Ureaplasma
5) Nocardia
6) Klebsiella
7) S. epidermidis
8) S. saprophyticus
Disease associated with recurrent infections with catalase (+) organisms
CGD
Enzyme deficient in CGD
NADPH oxidase
Pigment-producing bacteria: Yellow granules
Actinomyces israelii
Bacterial components that promote evasion of host immune response
Virulence factors
Virulence factor: Binds Fc region of IgG, preventing opsonization and phagocytosis
Protein A
Virulence factor: Secreted by SHiN to colonize respiratory mucosa
IgA protease
Virulence factor: Shares similar epitopes to human cellular proteins (molecular mimicry); possibly underlies the autoimmune response seen in acute rheumatic fever
M protein
Virulence factor: Needle-like protein appendage facilitating direct delivery of toxins from certain gram-negative bacteria to eukaryotic host cell
Injectisome aka type III secretion system
Bacteria: Protein A
S. aureus
Bacteria: M protein
GABHS
Exotoxin vs endotoxin: Gram-positive and gram- negative bacteria
Exotoxin
Exotoxin vs endotoxin: Secreted from cell
Exotoxin
Exotoxin vs endotoxin: Polypeptide
Exotoxin
Exotoxin vs endotoxin: LPS
Endotoxin
Exotoxin vs endotoxin: Encoded in plasmid or bacteriophage
Exotoxin
Exotoxin vs endotoxin: Encoded in bacterial chromosome
Endotoxin
Exotoxin vs endotoxin: High toxicity, low fatal dose
Exotoxin
Exotoxin vs endotoxin: Low toxicity, high fatal dose
Endotoxin
Exotoxin vs endotoxin: Fever, shock, DIC
Endotoxin
Exotoxin vs endotoxin: Induces antibodies called antitoxins (antigenic)
Exotoxin
Exotoxin vs endotoxin: Poorly antigenic
Endotoxin
Exotoxin vs endotoxin: Toxoids used as vaccines
Exotoxin
Exotoxin vs endotoxin: No toxoids or vaccines available
Endotoxin
Exotoxin vs endotoxin: Stable at 100C for 1 hour
Endotoxin
Exotoxin vs endotoxin: Destroyed rapidly at 60C
Exotoxin
Exotoxin vs endotoxin: Meningococcemia
Endotoxin
Heat stable enterotoxin
Staphylococcal enterotoxin
Toxin and bacteria: Inactivate elongation factor (EF-2)
1) Diphtheria toxin, C. diphtheriae
2) Exotoxin A, P. aeruginosa
Toxin and bacteria: Inactivate 60S ribosome
1) Shiga toxin, Shigella spp
2) Shiga-like toxin, EHEC O157: H7
Toxin and bacteria: Overactivates adenylate cyclase (increases cAMP) > increases Cl− secretion in gut and H2O efflux
Heat-labile toxin (LT), ETEC
[Labile in the Air (Adenylate cyclase), Stable in the Ground (Guanylate cyclase)]
Toxin and bacteria: Overactivates guanylate cyclase (increases cGMP) > decreases resorption of NaCl and H2O in gut
Heat-stable toxin (ST), ETEC
[Labile in the Air (Adenylate cyclase), Stable in the Ground (Guanylate cyclase)]
Toxin and bacteria: Mimics the adenylate cyclase enzyme (increases cAMP)
Edema toxin, B. anthracis
Toxin and bacteria: Overactivates adenylate cyclase (increases cAMP) by permanently activating Gs > increases Cl− secretion in gut and H2O efflux
Cholera toxin, V. cholerae
Toxin and bacteria: Overactivates adenylate cyclase (increases cAMP) by disabling Gi, impairing phagocytosis to permit survival of microbe
Pertussis toxin, B. pertussis
Toxin and bacteria: Proteases that cleave SNARE
1) Tetanospasmin, C. tetani
2) Botulinum toxin, C. botulinum
Toxin: GI mucosal damage > dysentery
Shiga toxin
Toxin: HUS
1) Shiga toxin
2) Shiga-like toxin
Toxin: Edematous borders of black eschar
Edema toxin of cutaneous anthrax
Toxin: 100-day cough in adults
Pertussis toxin
Toxin: Target Renshaw cells
Tetanospasmin
Toxin: Target NMJ cells
Botulinum toxin
Toxin: Prevents release of inhibitory (GABA and glycine)
Tetanospasmin
Toxin: Prevents release of stimulatory (ACh) signals
Botulinum toxin
Toxin: Spastic paralysis
Tetanospasmin
Toxin: Flaccid paralysis
Botulinum toxin
Toxin, bacteria: Phospholipase (lecithinase) that degrades tissue and cell membranes
Alpha toxin, C. perfringens
Toxin, bacteria: Protein that degrades cell membrane
Streptolysin O, S. pyogenes
ADP ribosylating A-B toxins
1) Diphtheria toxin
2) Exotoxin A
3) Shiga toxin
4) Shiga-like toxin
5) Heat-labile toxin
6) Edema toxin
7) Cholera toxin
8) Pertussis toxin
9) Tetanospasmin
10) Botulinum toxin
T/F EHEC invades host cells
F
Toxin, bacteria: Binds to MHC II and TCR outside of antigen binding site to cause overwhelming release of IL-1, IL-2, IFN-γ, and TNF-α > shock
1) TSST-1, S. aureus
2) Exotoxin A, S. pyogenes
Manifestations of alpha toxin
1) Myonecrosis > gas gangrene
2) Double zone of hemolysis on BAP
Toxin, bacteria: Scalded skin syndrome
Exfoliative toxin, S. aureus
Toxin: Food poisoning caused by S. aureus
Enterotoxin
Host antibodies against this toxin is used to detect rheumatic fever
Streptolysin O (ASO)
T/F ASO is responsible for post streptococcal GN
F
Ability to take up naked DNA (i.e., from cell lysis) from environment (also known as “competence”)
Transformation
Plasmid that contains genes required for sex pilus and conjugation
F+ plasmid
Sex pilus on F+ bacterium contacts F− bacterium. A single strand of plasmid DNA is transferred across the conjugal bridge (also known as the “mating bridge”)
F+ x F- Conjugation
T/F Chromosomal DNA is transferred in F+ x F-conjugation
F
Transfer of plasmid and chromosomal genes
Hfr x F- conjugation
Segment of DNA (e.g., transposon) that can “jump” (excision and reintegration) from one location to another, can transfer genes from plasmid to chromosome and vice versa.
Transposition
A “packaging” event
Generalized transduction
An “excision” event
Specialized transduction
Lytic phage infects bacterium, leading to cleavage of bacterial DNA. Parts of bacterial chromosomal DNA may become packaged in viral capsid. Phage infects another bacterium, transferring these genes.
Generalized transduction
Lysogenic phage infects bacterium; viral DNA incorporates into bacterial chromosome. When phage DNA is excised, flanking bacterial genes may be excised with it. DNA is packaged into phage viral capsid and can infect another bacterium.
Specialized transduction
Genes for these 5 bacterial toxins are encoded in a lysogenic phage
[ABCDE]
1) Shiga-like toxin
2) Botulinum toxin
3) Cholera toxin
4) Diphtheria toxin
5) Erythrogenic toxin of S. pyogenes
Differentiates staph from strep
Catalase
Staph (+)
Strep (-)
Differentiates S. aureus from S. epidermis and saprophyticus
Coagulase
S. aureus (+)
Differentiates S. epidermis from saprophyticus
Novobiocin sensitivity
Epidermidis, sensitive
Saprophyticus, resistant
Alpha hemolytic strep
S. pneumoniae
Viridans strep
Beta hemolytic bacteria
1) S. pyogenes
2) S. agalactiae
3) S. aureus
4) L. monocytogenes
Gamma hemolytic strep
Group D enterococcus (faecalis and faecium)
Group D nonenterococcus (bovis)
Differentiates S. pneumoniae from viridans strep
1) Optochin sensitivity (pneumoniae is sensitive)
2) Bile solubility (pneumoniae is bile soluble)
3) Capsule (pneumoniae has capsule)
Differentiates S. pyogenes from agalactiae
Bacitracin sensitivity (pyogenes is sensitive)
Differentiates Group D enterococcus from nonenterococcus
Growth in 6.5% NaCl (enterococcus grows)
Lancefield Group A strep
S. pyogenes
Lancefield Group B strep
S. agalactiae
Lancefield Group D strep
Enterococci and nonenterococci
Common characteristic growth of Group D streptococci
Growth in bile
Bacteria: Meningitis in newborns
1) Group B strep
2) L. monocytogenes
MRSA is resistant to
1) Methicillin
2) Nafcillin
Mechanism of resistance of MRSA
Altered PBP
Toxin and bacteria: Associated with prolonged use of vaginal tampons or nasal packing
TSST-1, S. aureus
A toxic shock– like syndrome associated with painful skin infection
S. pyogenes TSS
T/F Staphylococcal enterotoxin is preformed
T
Incubation period of S. aureus food poisoning
2-6 hours
Toxin responsible for abscess formation of S. aureus
Coagulase
Bacteria: Adherent biofilms in prosthetic devices
S. epidermidis
Bacteria: Most common cause of uncomplicated UTI in young women
E. coli
Bacteria: Second most common cause uncomplicated UTI in young women
S. saprophyticus
Bacteria: Normal skin flora that contaminates blood cultures
S. epidermidis
T/F S. aureus commonly colonizes the nares
T
S. aureus superantigen
TSST-1
Lancet-shaped, gram-positive, encapsulated diplococci
S. pneumoniae
S. pneumoniae is the most common cause of
MOPS
1) Meningitis
2) Otitis media in children
3) Pneumonia
4) Sinusitis
Bacteria: Rusty sputum
S. pneumoniae
Bacteria: Ventilator-associated pneumonia
P. aeruginosa
Bacteria: Sepsis in sickle cell disease and splenectomy
S. pneumoniae
T/F S. pneumoniae is non-virulent without capsule
T
Bacteria: Normal flora of oropharynx that cause dental caries
Viridans, S. mutans
[Viridans live in the MOUTH because they are not afraid op-to-chin (of-the-chin)]
Bacteria: Normal flora of oropharynx that cause subacute bacterial endocarditis at damaged heart valves
Viridans, S. sanguinis
Bacteria: Erysipelas
S. pyogenes
Bacteria: Scarlet fever
S. pyogenes
Bacteria: Colonizes vagina and may cause pneumonia, meningitis and sepsis in babies
S. agalactiae
Bacteria: Club-shaped
C. diphtheriae
Bacteria: TSS-like syndrome
S. pyogenes
Bacteria: Necrotizing fasciitis
S. pyogenes
Bacteria: Produces CAMP factor, which enlarges the area of hemolysis formed by S. aureus
S. agalactiae
Bacteria: PYR (+)
S. pyogenes
Criteria for rheumatic fever
Jones criteria
Major criteria for rheumatic fever
JONES
1) Joints
2) Carditis
3) Nodules
4) Erythema marginatum
5) Sydenham chorea
More commonly precedes post streptococcal GN: Impetigo vs pharyngitis
Impetigo
Bacteria: Sandpaper-like texture of skin
S. pyogenes (scarlet fever)
Bacteria: Strawberry tongue
S. pyogenes (scarlet fever)
Bacteria: Hippurate (+)
S. agalactiae
When to screen pregnant women for group B strep
35-37 weeks AOG
Management for pregnant women with (+) group B strep colonization on culture
Intrapartum Penicillin
T/F Enterococci are normal colonic flora
T
Normal colonic flora that cause subacute endocarditis
Enterococci
T/F Enterococci can cause UTI
T
T/F Enterococci can cause biliary tract infections
T
Subgroup of enterococci that are an important cause of nosocomial infection
Vancomycin-resistant enterococci
Group D nonenterococcus that can cause subacute bacterial endocarditis and associated with colon Ca
S. bovis
G+ rods with metachromatic (blue and red) granules
C. diphtheriae
Spore-forming bacteria (3)
1) Bacillus
2) Clostridium
3) Coxiella
(+) Elek test
C. diphtheriae
Phase of bacterial growth wherein spores can be formed
End of stationary phase (nutrients are limited)
T/F Spores have metabolic activity
F
How to kill spore-forming bacteria
Autoclave at 121C for 15 minutes
Causes antibiotic-associated colitis
C. difficile
Causes gas gangrene
C. perfringens
Also known as St. Anthony’s Fire
Erysipelas
Means by which erysipelas rapidly spreads and invades
Lymphatics
T/F Diazepam can be given for muscle spasms caused by C. tetani
T
T/F Botulinum toxin is preformed
T
T/F Botulinum toxin is heat-stable
F
T/F In babies, ingestion of preformed botulinum toxin causes floppy baby syndrome
F, ingestion of SPORES in honey
Toxin: C. difficile
1) Toxin A
2) Toxin B
Toxin: C. difficile, enterotoxin, binds
to the brush border of the gut
Toxin A
Toxin: C. difficile, cytotoxin, causes cytoskeletal disruption via actin depolymerization > pseudomembranous colitis > diarrhea
Toxin B
Pseudomembranous colitis is often due to antibiotic use especially ___
1) Clindamycin
2) Ampicillin
C. difficile, diagnostic modality
Detection of one or both toxins in STOOL by PCR
C. difficile, treatment
1) Metronidazole
2) Oral vancomycin
Lesion of cutaneous anthrax
PAINLESS papule surrounded by vesicles > PAINLESS necrotic ulcer with black eschar
Flu-like symptoms that rapidly progress to fever, pulmonary hemorrhage, mediastinitis, and shock
Pulmonary anthrax (inhalation of spores)
Bacteria: Reheated rice syndrome
B. cereus
T/F B. cereus: Keeping rice warm results in germination of spores and enterotoxin formation
T
B. cereus food poisoning, incubation period before nausea and vomiting
1-5 hours
B. cereus, toxin
Cereulide
T/F Cereulide is preformed
T
B. cereus food poisoning, incubation period before watery, nonbloody diarrhea, and GI pain
8-18 hrs
Bacteria: Cold deli meats
L. monocytogenes
Transmission of L. monocytogenes to newborns
1) Transplacental
2) Vaginal during birth
Long branching filamentous bacteria, normal oral flora
Actinomyces
Long branching filamentous bacteria, found in soil
Nocardia
Form “rocket tails” (via actin polymerization) that allow intracellular movement and cell-to-cell spread across cell membranes, thereby avoiding antibody
L. monocytogenes
Oral/facial abscesses that drain through sinus tracts
Actinomyces
Caused by nocardia in immunocompromised individuals
Pulmonary infections
Caused by nocardia after trauma in immunocompetent individuals
Cutaneous infections
Actinomyces, treatment
Pencillin [SNAP]
Nocardia, treatment
Sulfonamides [SNAP]
Only G+ organism to produce endotoxin
L. monocytogenes
Amnionitis, septicemia, and spontaneous abortion in pregnant women
L. monocytogenes
T/F BCG causes false negative PPD
F, false POSITIVE
Cause false negative PPD
1) Anergic individuals (steroids, malnutrition, immunocompromised)
2) Sarcoidosis
Granulomatosis infantiseptica
L. monocytogenes
L. monocytogenes causes this disease in healthy individuals
Mild gastroenteritis
L. monocytogenes causes this disease in immunocompromised individuals
Meningitis
T/F Mild GE caused by L. monocytogenes is self-limited
T
Treatment for L. monocytogenes in infants, immunocompromised, and elderly
Ampicillin
Diagnostic modality for M. tuberculosis that has fewer false positives from BCG vaccination
IGRA (Interferon-γ release assay)
MOTT that causes disseminated, non-TB disease in AIDS
M. avium-intracellulare
Prophylaxis for M. avium-intracellulare is given to patients when
CD4+ count less than 50 cells/mm3
Prophylaxis for M. avium-intracellulare (drug)
Azithromycin
Produced by virulent strains of mycobacteria, inhibiting macrophage maturation and induces release of TNF-alpha
Cord factor
Found on mycobacteria, inhibiting phagolysosomal fusion
Sulfatides
Mycobacterium that causes cervical lymphadenitis in children
M. scrofulaceum
Mycobacterium that causes hand infection in aquarium handlers
M. marinum
T/F All mycobacteria are acid fast
T
Mycobacterium that infects skin and superficial nerves—“glove and stocking” loss of sensation
M. leprae
T/F M. leprae cannot be grown in vitro
T
Reservoir that can be used to grow M. leprae
Armadillos
2 forms of Hansen disease
1) Lepromatous
2) Tuberculoid
Form of Hansen Disease: Presents diffusely over skin, with leonine facies
Lepromatous
Form of Hansen Disease: Limited to a few hypothetic, hairless skin plaques
Tuberculoid
Form of Hansen Disease: High cell-mediated immunity, largely Th1
Tuberculoid
Form of Hansen Disease: Highly communicable
Lepromatous
Form of Hansen Disease: Low cell-mediated immunity, largely humoral Th2
Lepromatous
Treatment for Tuberculoid Hansen Disease
Dapsone + Rifampin
Treatment for Lepromatous Hansen Disease
Dapsone + Rifampin + Clofazimine
Differentiates N. meningitides from N. gonorrheae
Maltose fermentation (meningitidis ferments)
Coccoid rods (2)
1) H. influenzae
2) B. pertussis
3) Pasteurella
4) Brucella
Comma-shaped, oxidase (+)
1) C. jejuni
2) V. cholerae
3) H. pylori
Darting motility
C. jejuni
Comma-shaped, grows in 42C
C. jejuni
Comma-shaped, grows in alkaline media
V. cholerae
Comma-shaped, produces urease
H. pylori
Fast lactose fermenters
KEE
1) Klebsiella
2) E. coli
3) Enterobacter
Slow lactose fermenters
CS
1) Citrobacter
2) Serratia
Lactose non-fermenter, oxidase (+)
Pseudomonas
Differentiates lactose non-fermenters, oxidase (-)
H2S production (TSI agar)
Produce H2S on TSI
SPY
Salmonella
Proteus
Yersinia
Does not produce H2S on TSI
Shigella
Weak lactose fermenter
Serratia
Growth of lactose fermenters on EMV
Purple/black
Gonococci vs meningococci: No vaccine due to antigenic variation of pilus proteins
Gonococci
Gonococci vs meningococci: Septic arthritis
Gonococci
Gonococci vs meningococci: Waterhouse-Friderichsen syndrome
Meningococci (meningococcemia)
Gonococci vs meningococci: Fitz-Hugh-Curtis syndrome
N. gonorrheae
Mode of transmission of gonococci
1) Sexual
2) Perinatal
Mode of transmission of meningococci
Respiratory and oral secretions
N. gonorrhea, disease caused in neonates
Neontal conjunctivitis
N. gonorrhea, prevents neonatal transmission
Erythromycin ointment
N. meningitidis, prophylaxis for close contacts
1) Rifampin
2) Ciprofloxacin
3) Ceftriaxone
N. gonorrheae, treatment
Ceftriaxone + azithromycin or doxycycline for possible chlamydial coinfection
N. meningitidis, treatment
Ceftriaxone or Pen G
H. influenzae, transmission
Aerosol
Legionella, diagnosis
Antigen detection from urine
Legionella, electrolyte abnormality
Hyponatremia
Legionella, transmission
Aerosol FROM ENVIRONMENTAL SOURCE (no person to person transmission)
Bacteria that can be grown with H. influenzae and provide Factor V through hemolysis of RBC
S. aureus
Causes epiglotitis in children seen as thumb sign on lateral neck radiograph
H. influenzae
H. influenzae, mucosal infection, treatment
Amoxicillin
H. influenzae, meningitis, treatment
Ceftriaxone
H. influenzae, prophylaxis for close contact with person with H. influenzae meningitis
Rifampin
T/F H. influenzae causes flu
T
Legionella, treatment
Macrolide or quinolone
Severe pneumonia (often unilateral and lobar), fever, GI and CNS symptoms
Legionnaire’s disease
Mild flu-like syndrome caused by Legionella
Pontiac fever
Grape-like odor
P. aeruginosa
Endotoxin vs exotoxin: Produced by P. aeruginosa
Both
Swimmer’s ear
P. aeruginosa
E. coli virulence factors: Cystitis and pyelonephritis
Fimbriae
E. coli virulence factors: Pneumonia and neonatal meningitis
Capsule
E. coli virulence factors: Septic shock
LPS
E. coli strain: Clinical manifestations similar to Shigella
EIEC
E. coli strain: Traveler’s diarrhea
ETEC
E. coli strain: Heat-stable and heat-labile toxins
ETEC
E. coli strain: Adheres to apical surface, flattens villi, prevents absorption, hence causes diarrhea in children
EPEC
E. coli strain: Shiga-like toxin
EHEC
E. coli strain: Dysentery
EHEC
E. coli strain: HUS
EHEC
Distinguishes EHEC from other E. coli
Does not ferment Sorbitol
Used for multi-drug resistant Pseudomonas
1) Colistin
2) Polymyxin B
Wound infection in burn victims
P. aeruginosa
Lobar pneumonia in alcoholics and diabetics
Klebsiella
Major cause of bloody diarrhea especially in children
C. jejuni
Pet feces, contaminated milk, pork
Yersinia enterocolitica
Ecthyma gangrenosum
P. aeruginosa
Cause pseudoappendicitis (right lower abdominal pain due to mesenteric adenitis and/or terminal ileitis)
Y. enterocolitica
Lyme disease
Borrelia burgdorferi
Chronic pneumonia in cystic fibrosis patients
P. aeruginosa, due to mucoid polysaccharide capsule > biofilm formation
Rapidly progressive, necrotic cutaneous lesion caused by Pseudomonas bacteremia. Typically seen in immunocompromised patients.
Ecthyma gangrenosum
HUS triad
1) Anemia
2) Thrombocytopenia
3) Acute renal failure due to micro thrombi formation
RBC morphology in HUS
Schistocytes
Currant jelly sputum
Klebsiella
Transmission of C. jejuni
Fecal-oral
a) Person-to-person
b) Contact with infected animals (dogs, cats, pigs)
Aspiration pneumonia
Klebsiella
Cause reactive arthritis (antecedent infections) (2)
1) C. jejuni
2) C. trachomatis (Reiter syndrome)
Abscess in lungs and liver
Klebsiella
Reservoir of Salmonella spp
Humans and animals EXCEPT S. typhi (humans only)
Salmonella vs Shigella: Hematogenous spread
Salmonella spp
Salmonella vs Shigella: Inactivated by gastric acid, hence large inoculum required
Salmonella spp
Salmonella vs Shigella: Antibiotics PROLONGS duration of fecal excretion
Salmonella spp
Vi capsule
S. typhi
Immune response (predominant cell): S. typhi
Monocytes
Immune response (predominant cell): Salmonella other than typhi
PMN
Immune response (predominant cell): Shigella
PMN
GI manifestation: S. typhi
Constipation followed by diarrhea
GI manifestation: Salmonella other than typhi
Bloody diarrhea
Rose spots on abdomen
S. typhi
Bacillary dysentery
Shigella
Forms of vaccine for S. typhi
1) Oral (live attenuated)
2) IM (capsular polysaccharide)
Risk factor for MALT lymphoma
H. pylori
H. pylori, most common initial treatment
Triple therapy: Amoxicillin (Metronidazole if with Penicillin allergy) + Clarithromycin + PPI
Carrier state with gallbladder colonization
S. typhi
Common sources include poultry, eggs, pets, and turtles
Salmonella other than typhi
Shigella spp that causes most severe disease (produces most toxin)
S. dysenteriae
Shigella spp that causes least severe disease (produces least toxin)
S. sonnei
Key pathogenic mechanism of Shigella
Invasion (toxin)
S. typhi, treatment
Ceftriaxone or fluoroquinolone
Biggest spirochete
Borrelia
Flu-like symptoms, myalgias, jaundice, photophobia with conjunctival suffusion (erythema without exudate)
Leptospirosis
Icterohemorrhagic leptospirosis
Weil disease
Ixodes deer tick is vector for (3)
1) Borrelia
2) Anaplasma
3) Babesia
Natural reservoir of Borrelia
Mouse
Facial nerve palsy (typically bilateral), arthritis, cardiac block, erythema chronic migrans
Borrelia burgdorferi
Borrelia burgdorferi, treatment
Ceftriaxone
Doxycycline
Prevalent among surfers and in tropics (i.e. Hawaii)
Leptosipra interrogans
Jaundice and azotemia from liver and kidney dysfunction, fever, hemorrhage, and anemia
Weil disease
Lesion, primary syphilis
Painless chancre
Lesion, secondary syphilis
Maculopapular rash and condylomata lata
Lesion, tertiary syphilis
Gumma
T/F Latent phase of syphilis is characterized by ⊕ serology without symptoms
T
Stage of syphilis: Disseminated disease
Secondary
Stage of syphilis: Aortitis due to vasa vasorum destruction
Tertiary
Stage of syphilis: Tabes dorsalis
Tertiary
Stage of syphilis: Argyll Robertson pupil
Tertiary
Diagnosis of neurosyphilis
CSF VDRL and PCR
Placental transmission of syphilis, trimester
After first trimester
Clinical manifestations of congenital syphilis
1) Facial abnormalities (rhagades - linear scars at angle of mouth, saddle nose, notched Hutchinson teeth, mulberry molars, short maxilla)
2) Saber shins
3) CN VIII deafness
Antibody detected by VDRL
Anti-cardiolipin
False (+) VDRL
1) Viral infection (mono, hepatitis
2) Drugs
3) Rheumatic fever
4) Lupus and leprosy
Cat scratch disease
Bartonella
Relapsing fever
Borrelia recurrentis
Undulant fever
Brucella
Bloody diarrhea from exposure to puppies and livestock
Campylobacter
Parrots
Chlamydia psitacci (psittacosis)
Jarisch-Herxheimer reaction
T. pallidum (release of endotoxin from killed bacteria)
Aerosols of cattle/sheep amniotic fluid
Coxiella burnetti
Vector of Ehrlichia chaffeensis
Ambylomma (Lone Star tick)
Tularemia
Francisella tularensis
Epidemic typhus
Rickettsia prowazekii
Rocky Mountain spotted fever
Rickettsia rickettsii
Endemic typhus is aka
Murine typhus
Endemic typhus
Rickettsia typhi
Plague
Yersinia pestis
Ticks, rabbits, deer fly
Francisella tularensis
Rat flea (Xenopsylla cheopsis)
Rickettsia typhi (endemic typhus)
Human body louse (Pediculus humanus humanus)
Rickettsia prowazeki (epidemic typhus)
Dermacentor (dog tick)
Rickettsia rickettsii (dog tick)
Rats and prairie dogs are reservoir
Yersinia pestis
T/F Gardnerella vaginalis is sexually transmitted
F
Treatment for ALL rickettsial diseases and vector-borne illness
Doxycycline
Rash in palms and soles (3)
1) Coxsackie A (hand, foot, and mouth disease
2) Secondary syphilis
3) Rocky mountain spotted fever
Rash of rocky mountain spotted fever typically starts at
Wrists and ankles
Rash of typhus typically starts at
Centrally, with sparing of palms and soles
Monocytes with morulae (berry-like inclusions) in cytoplasm
Ehrlichiosis
Granulocytes with morula in cytoplasm
Anasplasmosis
Most common cause of culture negative endocarditis
Coxiella burnetti
Elementary and reticulate bodies
Chlamydia
Chlamydia morphology that is infectious and enters cells via endocytosis
Elementary body
[Enfectious, Enters cell, Endocytosis]
Chlamydia morphology that replicates in cell by fission and reorganizes
Reticulate body
[Replicate, Reorganize into elementary bodies]
Atypical “walking” pneumonia; x-ray looks worse than patient
Mycoplasma pneumoniae
Mimic TB (granuloma formation)
Systemic mycoses
Bird or bat droppings
Histoplasma capsulatum
Chronic infection, cause blindness due to follicular conjunctivitis
Chlamydia trachomatis (Type A-C)
Neonatal pneumonia, stacatto cough; neonatal conjunctivitis; PID
Chlamydia trachomatis (Type D-K)
Lymphogranuloma venereum
Chlamydia trachomatis (Type L1-3)
Swollen, painful inguinal lymph nodes that ulcerate are known as
Buboes
Pneumoniaw with hight tiger of cold agglutinins (IgM) that can lyse RBCs
Mycoplasma pneumoniae
Mycoplasma pneumoniae, treatment
1) Macrolides
2) Fluoroquinolones
3) Doxycycline
Dimorphic fungi morphology: Cold
Fungi
Dimorphic fungi morphology: Heat
Yeast
The only dimorphic fungi that is not yeast in tissue
Coccidioidomycosis (spherule in tissue)
Outbreaks in military recruits and prisons
Mycoplasma pneumoniae
Systemic mycoses, treatment for LOCAL infection
Fluconazole or itraconazole
Systemic mycoses, treatment for systemic infection
Amphotericin B
T/F Systemic mycosis = person-to-person transmission
F
Systemic mycoses (4)
1) Histoplasmosis
2) Blastomycosis
3) Coccidioidomycosis
4) Paracoccidioidomycosis
Systemic mycosis: Broad-based budding
Blastomycosis
Systemic mycosis: Smaller than RBCs and found within macrophages
Histoplasmosis
Systemic mycosis: Same size as RBCs
Blastomycosis
Systemic mycosis: T/F Can disseminate to bone and skin
T
Systemic mycosis: Captain’s wheel morphology, much larger than RBCs
Paracoccidioidomycosis
Systemic mycosis: Case rate increase after earthquakes as spores are thrown into air resulting in lung spherules
Coccidioidomycosis
Systemic mycosis: Latin America
Paracoccidioidomycosis
Systemic mycosis: San Joaquin valley fever
Coccidiodomycosis
Systemic mycosis: Desert bumps and desert rheumatism
Coccidioidomycosis
Cutaneous mycoses
1) Dermatophytes (MET: Microsporum, Epidermophyton, Trichophyton)
2) Tinea versicolor
Clinical name given to dermatophyte (cutaneous fungal) infections
Tinea
Branching septate hyphae visible on KOH preparation with blue fungal stain
Dermatophytes
T/F Tinea capitis is associated with lymphadenopathy
T
Ringworm with central clearing
Tinea corporis
Tinea that often does not show central clearing
Tinea cruris
3 varieties of tinea pedis
1) Interdigital
2) Moccasin distribution
3) Vesicular
Most common variety of tinea pedis
Interdigital
T/F Tinea versicolor is a dermatophyte
F
Degradation of lipids produces acids that damage melanocytes and cause hypopigmented and/or pink patches
Tinea versicolor
Tinea versicolor treatment
Selenium sulfide
No rash. No vector. Causative organism can survive outside in its endospore form.
Coxiella burnetti
Endocarditis in IV drug users
Candida
Candida treatment: Vaginal candidiasis
Topical azole
Candida treatment: Oral/esophageal candidiasis
1) Nystatin
2) Fluconazole
3) Caspofungin
Candida treatment: Systemic candidiasis
Amphotericin B
Fungal infection in CGD
Aspergillus fumigatus (invasive aspergillosis)
Fungal infection in asthma and cystic fibrosis
Aspergillus fumigatus (allergic bronchopulmonary aspergillosis, ABPA)
Heavily encapsulated yeast
C. neoformans
Fungal infection in ketoacidotic diabetic and/or neutropenic patients (e.g., leukemia)
Mucor and Rhizopus
Fungal infection that presents as diffuse, bilateral ground-glass opacities on CXR/CT
P. jiroveci
Fungus ball in lung cavities especially after TB infection
Aspergillus fumigatus (aspergilloma)
Soil and pigeon droppings
C. neoformans
Aflatoxins
Aspergillus fumigatus
“Soap bubble” lesions in brain
C. neoformans
Septate hyphae that branch at 45-degree angle
Aspergillus fumigatus
Opportunistic fungal infections
1) C. albicans
2) A. fumigatus
3) C. neoformans
4) Mucor and Rhizopus
5) P. jirovecii
6) S. schenckii
T/F Aspergillus are dimorphic
F
Eucalyptus trees
C. neoformans
C. neoformans, mode of transmission
Inhalation
Fungi proliferate in blood vessel walls, penetrate cribriform plate, and enter brain; rhinocerebral, frontal lobe abscess; cavernous sinus thrombosis
Mucor and Rhizopus
Disc-shaped yeast forms on methenamine silver stain of lung tissue
P. jiroveci
P. jiroveci, treatment/prophylaxis
TMP-SMX
When to start prophylaxis for P. jiroveci
CD4+ less than 200 cells/mm3
Dissemination of S. schenckii
Lymphatic
S. schenckii treatment
1) Itraconazole
2) KI
Bloating, flatulence, foul-smelling, fatty diarrhea (often seen in campers/hikers)
Giardiasis
Severe diarrhea in AIDS
Cryptosporidium
Transmission: Giardia lamblia
Cysts in water
Transmission: E. hystolytica
Cysts in water
Transmission: Cryptosporidium
Oocysts in water
Black necrotic eschar on face
Mucor and Rhizopus
Treatment, nucor and rhizopus
Surgical debridement
Amphotericin B
Diagnosis: G. lamblia
Trophozoites or cysts in stool
Diagnosis: E. hystolytica
1) Serology
2) Trophozoites with RBCs in cytoplasm
3) Cysts (up to 4 nuclei)
Diagnosis: Cryptosporidium
Acid fast oocysts
Treatment: G. lamblia
Metronidazole
Treatment: E. hystolytica, symptomatic
Metronidazole
Treatment: E. hystolytica, asymptomatic cyst passer
Iodoquinol
Prevention, Cryptosporidium
Filter water supplies
Protozoa that cause CNS infections
1) Toxoplasma gondii
2) Naegleria fowleri
3) Trypanosoma brucei
Congenital toxoplasmosis triad
1) Choriotetintis
2) Hydrocephalus
3) Intracranial calcification
Cysts in meat (most common); oocysts in cat feces; crosses placenta
T. gondii
African sleeping sickness
T. brucei
Tsetse fly
T. brucei
Ring-enhancing lesions on CT/MRI
T. gondii
