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162 Cards in this Set

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  • Back
These bugs do not Gram stain well (Nm)
(These Rascals May Microscopically Lack Color)

Treponema, Rickettsia, Mycobacteria, Mycoplasma, Legionella, Chlamydia
How are Treponema visualized?
dark field microscopy and fluorescent antibody staining (spirochete--too small to be visualized on G stain)
Why don't Rickettsia gram stain?
Why don't Mycobacteria gram stain? What stain do they require?
high lipid content cell wall requires acid-fast stain
Why don't Mycoplasma gram stain?
no cell wall
Why don't Legionella gram stain? What do they stain with?
primarily intracellular; silver stain
Why don't Chlamydia gram stain?
intracellular, lacks muramic acid in cell wall (remember: EBs and RBs; inclusion bodies stain with iodine)
Mechanism of superantigens?
bind to MHCII and Tcell receptor, activating large number of T cells to stimulate release of IFN-g and IL-2
2 main bugs that make superantigens?
S aureus, S pyogenes
2 impt S. aureus exotoxins? Clinical effects?
TSST-1; toxic shock syndrome (fever, rash, shock)
Enterotoxin; food poisoning

(both can act as superantigens)
Impt S pyogenes exotoxin? Clinical effects?
scarlet fever-erythrogenic toxin; scarlet fever and toxic shock-like syndrome
Bugs that make ADP-ribosylating A-B toxins?
Corynebacteria, E coli, B pertussis, V cholera
Mech of ADP-ribosylating A-B toxins?
interfere w/host cell fn: B(binding) component binds host recep, endocytosis; A(active) component attaches ADP-ribosyl to host protein, altering fn
What does Corynebacteria diphtheriae exotoxin do? Clinical effects?
diphtheria toxin: inactivates elongation factor (EF-2)(similar to pseudomonas exotoxin A); causes pharyngitis and pseudomembrane in throat
What does cholera toxin do? Clinical effects?
cholera enterotoxin: ADP ribosylation of Gs protein stim' AC, inc cAMP, inc pumping Cl and H2O into gut, voluminous rice-water diar
Exotoxins made by enterotoxigenic E coli (ETEC)? Clinical effects?
Heat labile toxin (LT): stim AC (cholera like mech) to inc cAMP
Heat stabile toxin (ST): stim GC to inc cGMP

causes fluid and elec loss, watery diar (traveler's diar)

Nm: Labile like the Air, Stable like the Ground
Exotoxin made by Bordetella pertussis? Clinical effects?
stims AC, causes whooping cough; inhib chemokine recep, causes lymphocytosis
Clostridium perfringes exotoxin? Clin effects?
alpha toxin (lecithinase): lysis of RBCs and endoth cells, causes gas gangrene
C. tetani exotoxin? Clin effects?
tetanospasmin: blocks release of inhib NTs (GABA, gly), causes tetanus, lockjaw
C. botulinum exotoxin? Clin effects?
botulinum toxin: blocks release of ACh, anti-chol sx, flaccid paralysis (esp in CNs); spores found in canned food, honey; floppy baby synd
Bacillus anthracis toxin? Clin effects?
anthrax toxin: 1 toxin in the complex is an AC; causes edema and cell death
Shigella exotoxin? Clin effects?
Shiga toxin, cleaves host rRNA, enhances cytokine release, causes HUS, dysentery
What other organism makes shiga-like toxin? Clin effects?
E coli EHEC, 0157:H7; bloody diar, like dysentery, HUS
Impt (non-superantigen) exotoxin of S pyogenes?
Streptolysin O: lyses RBCs; is ASO ab in rheum fever
What 3 pathways does endotoxin activate?
macrophages, complement (alt path), Hageman factor (coag cascade)
What are the effects of activated macrophages (by endotoxin)?
inc IL-1 -> fever
inc TNF -> fever, hemorr necrosis
inc NO -> hypotension (shock)
What are the effects of activated complement pathway (by endotoxin)?
inc C5a -> neutrophil chemotax
inc C3a -> hypotens, edema
What is the effect of activated Hageman factor (by endotoxin)?
activated coag cascade -> DIC
Is endotoxin heat stable?
What sugar does meningococci ferment?
maltose and glucose
What sugar does gonococci ferment?
glucose only
3 impt pigment producing bacteria? What color pigments?
S aureus (yellow/gold)
Pseudomonas (blue/green)
Serratia marcescens (red-thing maraschino cherries)
Impt G+ cocci
Staph, strep
Impt G+ cat+ cocci
Staph: aureus, epidermidis, saprophyticus
G+ cat+ coag+
S aureus
G+ cat+ coag-
S epid, S sapro
G+ cat+ coag- novobiocin sensitive
S epidermidis
G+ cat+ coag- novobiocin resistant
S saprophyticus
lab algorithm for GAS
G+ cocci, cat-, beta-hem, bacitracin sens
lab algorithm for GBS
G+ cocci, cat-, beta hem, bacitracin resistant
lab algorithm for viridans strep
G+ cocci, cat-, alpha hem, optochin R (no capsule)
lab algorithm for strep pneumo
G+ cocci, cat-, alpha hem, optochin S (capsule), +quellung
G+ cocci, cat-, gamma hem?
peptostreptococcus (anaerobe)
enterococcus (alpha or gamma hem)
G+ rods
Corynebacteria, Clostridium, Bacillus, Listeria, Actinomyces
which G+ rods are anaerobes?
clostridium, actinomyces
G- cocci
N meningitidis, N gonorrhoeae
G- cocci, maltose fermenter
N men
G- cocci, malt non ferm
N gon
G- rods, lactose nonfermenters
Shig, Salm, Prot, Pseudomonas, Yersinia
G- rods, lact nonferm, oxidase+
G- rods, lact nonferm, oxidase-
shig, salm, prot
G- rods, lact fast fermenters
Kleb, E coli, Enterobacter
G- rods, lact slow fermenters
Citrobacter, Serratia, Others
G- coccobacilli
H flu, Pasturella, brucella, B pertussis
H flu cult media?
choc agar w/ factors V(NAD) and X(hematin)
N gon
B pertussis
Bordet-Gengou (potato) agar
C diphtheria
Tellurite plate, Loffler's medium, blood agar
lowenstein-jensen agar
lactose-fermenting enterics
pink on MacConkey's
charcoal yeast extract agar buffered with inc iron and cysteine
Sabouraud's agar
Congo red stain
amyloid; apple green birefringence in polarized light (because of beta pleated sheets)
Borrelia, Plasmodium, trypanosomes, Chlamydia
PAS (periodic acid-Schiff)
stains glycogen, mucopolysaccharides; used to dx Whipple's ds
acid-fast bact
India ink
Cryptococcus neoformans
silver stain
fungi, PCP, legionella
Conjugation? Type of cell? Type of DNA?
direct cell to cell transfer; prok; chrom or plasmid
Transduction? Type of cell? Type of DNA?
phage mediated cell to cell transfer; prok; any gene (in generalized transduction)
Transformation? Type of cell? Type of DNA?
purified DNA taken up by a cell; prok or euk; any DNA
Transposition? Type of cell? Type of DNA?
DNA transfer to same or another chrom or plasmid w/in a cell; prok or euk; DNA sequences ("jumping genes")
What toxins are lysogenic?
(genetic code for toxin encoded in lysogenic phage)
Botulinum toxin, Cholera toxin, Diphtheria, Erythrogenic toxin (S pyog)
impt obligate aerobes? (Nm)
Nagging Pests Must Breathe; P AERuginosa is an AERobe

Nocardia, Pseudomonas, Mycobacterium TB (like the apices), Bacillus
Pseudomonas aeruginosa, common presentations?
(aerobic), in burn wounds, nosocomial pneumonia, and pneumonia in CF pts
impt obligate anaerobes?
Clostridiu, bacteroides, actinomyces
biochemical characteristics of anaerobes?
lack catalase and/or superoxide dismutase, thus are susceptible to oxidative damage
general characteristics of anaerobes?
foul smelling (short chain fatty acids), hard to culture, produce gas in tissue (CO2 and H2)
where are anaerobes normal flora?
GI tract
what antibiotics are ineffective a/g anaerobes?
aminoglycosides (b/c they require O2 to enter into bacterial cell)
Obligate intracellular bugs (Nm)
Stay inside (cells) when its Really Cold

Rickettsia, Chlamydia
Facultative intracellular bugs (Nm)
Some Nasty Bugs May Live FacultativeLY

Salmonella, Neisseria, Brucella, Mycobacterium, Listeria, Francisella, Legionella, Yersinia
Impt encapsulated bact?
Strep pneumo, H flu (esp B serotype), N men, Kleb pneumo
What does a pos quellung rxn indicate?
if encapsulated bug is present, capsule swells when specific anticapsular antisera are added
Impt spore forming bact?
G+ soil bugs (eg Bacillus anthracis, Clostridium perfringes, C. tetani)
Impt alpha-hemolytic bugs?
strep pneumo (cat-, optochin s), viridans strep (cat-, optochin r)
impt beta-hemolytic bugs?
staph aureus (cat+, coag+)
GAS (cat-, bacitracin s)
GBS (cat-, bacitracin r)
listeria monocytogenes (tumbling motility, meningitis in newborns, unpast milk)
what does catalase do?
degrades H2O2 (an antimicrob product of PMNs, and a substrate for myeloperoxidase)
coag pos staph? vs coag neg staph?
aureus vs epidermidis & saprophyticus
impt staph aureus (surface) virulence factor?
protein A: binds Fc-IgG, inhib comp fixation and phag
s aureus, inflam mediated ds?
skin infections, organ abscesses, pneumonia (often following viral flu, w/cavitations), acute endocarditis, osteomyelitis
s aureus, toxin mediated ds', and associated toxins?
toxic shock synd (TSST-1 (superant)), scalded skin synd (exfoliative toxin), rapid-onset food poisoning (enterotoxins)
GAS: major surface virulence factor?
M protein (inhib' opson, but Ab to M prot enhances host defenses)
GAS: pyogenic infections?
pharyngitis, skin infect (cellulitis, impetigo, nec fasc)
GAS: toxigenic infections?
toxic shock syndrome, scarlet fever
GAS: immunologic infections?
glomerulonephritis (following pharyngitis or skin infec)
rheumatic fever (following pharyngitis)
Sx of rheumatic fever? (Nm)
No "rheum" for SPECCulation
Subcut nodules, Polyarthritis, Erythema marginatum, Chorea, Carditis
Strep pneum is most common cause of: (Nm)
S pneumo MOPS are Most OPtochin Sensitive

Meningitis, Otitis media (in kids), Pneumonia, Sinusitis
s pneumo, 2 major virulence factors
IgA protease (allows mucosal colonization), capsule
which type of strep is assoc w/ "rusty" sputum, sepsis in sickle cell anemia and splenectomy?
GBS diseases?
pneumonia, meningitis, sepsis (mainly in babies)
enterococcal ds'?
UTIs and subacute bact endocarditis (SBE)
can you treat enterococci with pen G?
no! Pen G resistant; use aminoglycoside + vanc, except for VRE!
staph epidermidis ds'?
UTIs and SBE; infects prosthetics and catheters; component of normal skin flora; contaminates blood cultures
viridans strep lab diag?
alpha hem, optochin r (not afraid of-the-chin)
main types of viridans strep and their ds'?
strep mutans (dental caries)-normal oral flora
strep sanguis (SBE)
ID: G+, spore-forming, obligate anaerobic bacilli?
C. tetani toxin?
exotoxin blocks release of inhib NTs (glycine) from Renshaw cells in spinal cord -> tetanic paralysis (spastic)
C. botulinum toxin?
preformed, heat labile toxin , blocks release of ACh -> flaccid paralysis, floppy baby synd (honey)
C. perfringes toxin?
alpha toxin (lecithinase), causes myonecrosis, hemolysis, gas gangrene
C. difficile toxins? what condition do they cause?
enterotox (exotoxin A): fluid s/c and intest hemor
cytotoxin (exotoxin B): mucosal damage

pseudomembranous colitis
common antibiotics that cause pseudomembranous colitis?
amp (pen->inhib peptid cross linking), clinda (lincosamide->inhib 50S)
what do you treat pseudomemb colitis (C diff) with?
ID: G+ rods, w/long branching filaments resembling fungi (2 org')
Actinomyces and Nocardia
characteristic ds of actinomyces israelii?
oral/facial abscesses w/ yellow "sulfer granules" in sinus tracts
characteristic ds of nocardia?
pulm infection (w/abscesses) in immunocomp pts
how do you distinguish actinomyces from nocardia?
actinomyces: G+ anaerobe, sulfer granules have non acid fast rods
nocardia: G+ aerobe, weakly acid fast
Tx for actinomyces and nocardia? (Nm)

Sulfonamides (inhib DNA synth by folate inhib) for Nocardia
Actinomyces, use Penicillin (or Amp)
+surgery (both)
what are G- bugs resistant to?
generally, G- outer membrane layer inhib' entry of PEN G and VANC
(exception: N men suscept to Pen G)
but, may be susceptible to pen derivatives such as amp
Meningococci vs Gonococci:
maltose fermentation?
vaccine available?
mening: capsule, +maltose ferm, vaccine avail <2yo
gonococci: no capsule, -maltose ferm, no vaccine
gonococcal ds'?
gonorrhea, PID, septic arthritis, neonatal conjunctivitis, pharyngitis
meningococcal ds'?
meningitis, meningococcemia (purpura, DIC), Waterhouse-Friderichsen syndrome (DIC and bilat adrenal necrosis)
N gon tx?
ceftriaxone (+ doxy for chlamydial coverage)
N men tx? prophylaxis?
Pen G (or broad-spec cephalosporins--eg ceftriax)

prophylactic rifampin
H flu ds'? (Nm)

Epiglottitis, Meningitis, Otitis media, Pneumonia
most virulent H flu capsular type?
Hib (type B)
H flu virulence factors?
capsule, IgA protease
cult H flu on? (Nm)
kid w/flu, go to the five(V) and dime(X) to get choc

choc agar w/factor V(NAD) and X(hematin)
H flu meningitis or epiglottitis tx? prophylaxis?
ceftriaxone or cefotaxime (broad spec beta-lactamase resistant cephalos)
rifampin in close contacts
what does H flu vaccine contain? age given?
type B capsular polysaccharide conjugated to diphtheria toxoid or other protein; given b/t 2 and 18mos of age
what is the key metabolite that raises hypothalamic thermostat?
PGE2 (endog pyrogens cause inc arach acid, w/inc AA metabolites)
Enterobacteriaceae: serology (what antigens present)?
O antigen (somatic; part of LPS)
K antigen (capsular; antiphag; in Kleb and Salm)
H antigen (flagellar; except in Kleb & Shig--nonmotile)
gram __?
all ferment __?
oxidase __?
G-, all ferment glucose, oxidase-
non-lactose fermenters?
Shig, Salm, Yersinia -- more pathogenic than lactose ferm
Proteus (not so pathogenic)
lactose fermenters?
(pink on MacConkey)
Kleb, Ecoli, Enterobacter, Citrobacter, Serratia
facultative intracellular enterobacteriaceae?
salm, yersinia
Klebsiella causes: (Nm)
3 A's: Aspiration pneumonia, Abscesses in lungs, in Alcoholics

opportunistic, severe lobar pneumonia in alcholics, diabetics, COPD, and nosocomial UTIs
Klebsiella sputum?
red currant jelly
Salm vs Shig:
antibiotic response?
both: non lact ferm, invade mucosal, can cause bloody diar
Salm: motile, can invade further, dissem hematogenously; sx of salm can be prolonged by antibiotics, typically w/monocyte response, less virulent (10^5), animal reservoir
Shig: more virulent (10^1), no anim reservoir, transmitted by Food, Fingers, Feces, Flies
shigella toxin? mech? ds'?
shiga toxin; inhib prot synth by cleaving host rRNA; causes shigellosis (bacillary dysentery), may cause HUS
yersinia enterocolitica: common transmiss? ds'? what can it mimic?
usu transmiss via pet feces, contam milk, pork; enterocolitis (clinically indisting from shig or salm); can mimic Crohn's or appendicitis
contaminated seafood?
Vibrio parahaemolyticus or V. vulnificus
reheated rice?
Bacillus cereus
meats, mayo, custard; w/abrupt onset & offset
S aureus
reheated meat (double zone of hemolysis)
Clostridium perfringes
bulging cans, honey
Clostridium botulinum
undercooked meat
E coli O157:H7
poultry, meat, eggs
bugs causing bloody diarrhea
Campy, Salm, Shig, EHEC, EIEC, Yers, C diff, Entaemoeba histolytica
bugs causing watery diarrhea
ETEC, vibrio cholerae, C perfringes, protozoa (giardia, cryptosporidium (in imm-comp)), viruses (roto, adeno, noro)
cAMP inducing toxins
-vibrio cholerae toxin: activates Gs (rice-water diar)
-pertussis toxin: disables Gi, stim' AC (whooping cough); also inhib chemokine receptor, causing lymphocytosis
-Ecoli(heat labile toxin): stim AC
-Bacillus anthracis toxin: edema factor, =AC
which cAMP inducers act via ADP-ribosylation (to permenantly activate AC)
cholera toxin, pertussis toxin, E coli toxin
stain and cult for Legionella pneumophila?
silver stain, charcoal yeast extract w/iron and cysteine
(G stains poorly)
legionella ds?
legionnaire's ds: atypical pneumonia (dry, nonproduc cough)
pontiac fever (self-lim febrile illness w/o pneumonia)
legionella transmiss?
water sources (eg AC systems), no person-to-person transmiss
legionella tx?
erythromycin (or azith) (can penetrate into WBCs)
main pathogenesis of legionella?
intracellular survival
mycoplasma pneumoniae ds?
primary atypical walking pneumonia (mild interstitial)
mycoplas pneumoniae dx? culture media?
high titer of cold agglutinins (IgM); grown on Eaton's agar
at risk pop for mycoplasma pneumonia?
military barracks, prisons; common in young adults
mycoplasma cell wall/membrane characteristics?
no cell wall (therefore pen resistant); only bacterial membrane containing cholesterol
mycoplasma pneumonia tx?
tetra or erythro (resistant to beta-lactams!)