My Micro Part 1, USMLE Flashcards by Jonathan Paul Ladera

Bacterial structure: Rigid support

Peptidoglycan

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Bacterial structure: Major surface antigens (2)

1) Cell wall

2) Outer membrane (G-)

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Bacterial structure: Protects against osmotic pressure

Peptidoglycan

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Bacterial structure: Site of oxidative and transport enzymes

Plasma membrane

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Bacterial structure: Site of endotoxin

Outer membrane (G-)

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Bacterial structure: Space between the cytoplasmic membrane and outer membrane in G-

Periplasm

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Bacterial structure: Site of lipopolysaccharide

Outer membrane (G-); aka endotoxin

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Bacterial structure: Mediate adherence of bacteria to cell surface

Pilus/fimbria

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Bacterial structure: Motility

Flagellum

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Bacterial structure: Resistant to dehydration, heat, and chemicals

Spore

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Bacterial structure: Forms attachment between 2 bacteria during conjugation

Sex pilus

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Bacterial structure: Contains genes for antibiotic resistance, enzymes, and toxins

Plasmid

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Bacterial structure: Adherence to surfaces, especially foreign surfaces (e.g. indwelling catheters)

Glycocalyx

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Bacterial structure: Sugar backbone with peptide side chains cross- linked by transpeptidase

Peptidoglycan

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Bacterial structure: Lipoteichoic acid

Cell wall

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Bacterial structure: Lipid A

Outer membrane (G-)

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Bacterial structure: O polysaccharide

Outer membrane (G-)

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Bacterial structure: Phospholipid bilayer

Plasma membrane

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Bacterial structure: Contains hydrolytic enzymes, including beta lactamases

Periplasm

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Bacterial structure: Component of pilus/fimbria

Glycoprotein

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Bacterial structure: Component of flagellum

Protein

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Bacterial structure: Components of spore

1) Dipicolinic acid

2) Peptidoglycan

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Bacterial structure: Keratin-like coat

Spore

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Bacterial structure: DNA

Plasmid

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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

[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

[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

[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

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

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

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

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

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

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

Normal colonic flora that cause subacute endocarditis

Enterococci

T/F Enterococci can cause UTI

T/F Enterococci can cause biliary tract infections

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

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/F Botulinum toxin is preformed

T/F Botulinum toxin is heat-stable

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

B. cereus food poisoning, incubation period before nausea and vomiting

1-5 hours

B. cereus, toxin

Cereulide

T/F Cereulide is preformed

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

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

Mycobacterium that infects skin and superficial nerves—“glove and stocking” loss of sensation

M. leprae

T/F M. leprae cannot be grown in vitro

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

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

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

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

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

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

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

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

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