Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
128 Cards in this Set
- Front
- Back
|
what is the toxin in scalded skin syndrome
|
exfoliative toxin A & B (ET A & B)
|
|
|
food poisoning toxin from staph
|
enterotoxin SE (heat stable)
|
|
|
how do you diagnose toxin mediated staph aureus
|
in vitro culture, because they are not in the blood
|
|
|
3 mechanisms by which staph aureus evades host defenses
|
1. protein A
2. coagulase 3. hemolysins, leukocidins |
|
|
what does protein A of staph aureus bind to?
|
binds Fc region of IgG
|
|
|
what 3 mechanisms or enzymes does infectious staph aureus use to deeply invade and reach bloodstream?
|
1. hyaluronidase
2. staphylokinase 3. lipase |
|
|
what does staphylokinase do?
|
lyses formed clots
|
|
|
what does hyaluronidase do?
|
breaks down connective tissue
|
|
|
what is the most severe syndrome of scalded skin syndrome in neonates
|
ritters syndrome -> exfoliative toxin is released systemically after umbilicus is cut
|
|
|
infectious agent in IV drug user who presents with heart failure and tricuspid valve vegetations
|
staph aureus (acute endo)
|
|
|
use 1st generation cephalosporin in what 2 cases?
|
surgical prophylaxis, cellulitis
|
|
|
activity of 3rd generation cephalosporins
|
less active against gram positives, very broad gram negative; efficiently crosses BBB. uses: meningitis and sepsis
|
|
|
pt with chronic granulomatous dz (impaired neutrophil function) are vulnerable to what bug
|
staph aureus
|
|
|
what specific structural feature of ampicillin allows it to cover gram negative bacteria
|
amino group makes this drug more hydrophillic, allowing it to pass through porins in gram negative cell walls, extending spectrum to cover gram negatives
|
|
|
what drug would you use for resistant infections or patients who cannot tolerate penicillins due to penicillin allergy
|
aztreonam
|
|
|
2 side effects of cephalosporins
|
hypersensitivity + disulfiram like reaction
|
|
|
what generation is Keflex?
|
1st generation cephalosporin
|
|
|
what drug is a derivative of ampicillin, a carboxypenicllin, and a bactericidal beta-lactam antimicrobial
|
ticarcillin (ticar)
|
|
|
Ticarcillin (ticar) covers what clinically?
|
most gram negative bacteria, including pseudomonas and most enterobacteriaceae (proteus, enterobacter, serratia)
|
|
|
what do beta-lactamases do?
|
beta-lactamases (penicillinases) cleave the beta-lactam ring of the drug - inactivating it
|
|
|
what is the drug of choice for listeria and enterococcus?
|
ampicillin
|
|
|
what does ampicillin cover clincially?
|
extends spectrum of penicillins to cover gram negative organisms: proteus mirabilis, E coli, Salmonella, H. influeza
|
|
|
what drug do you use to treat Klebsiella?
|
Mezlocillin (Mezlin) or Piperacillin (Pipracil) - both ureidopenicillins, like carboxypenicillin,
|
|
|
aztreonam (azactam) covers what clinically?
|
gram negative, NO effect on gram + or anaerobic bacteria
|
|
|
if a patient has Pseudomonas, a penicillin allergy, and renal insufficiency what do you treat them with?
|
Aztreonam -> covers gram negatives such as pseudomonas and enterobacteriaceae. Not cross allergic with penicillins and not renal toxic like aminoglycosides
|
|
|
amoxicillin + clavulanic acid =
|
augmentin (PO)
|
|
|
piperacillin + tazobactam =
|
zosyn (IV)
|
|
|
ampicillin + sulbactam =
|
unasyn (IV)
|
|
|
function of clavulanic acid
|
binds to and inactivates many b-lactamases, preventing destruction of susceptible b-lactam antibiotics, which include all penicillins except for the semisynthetic penicllinase-resistant generation (nafcillin)
|
|
|
what are the 4 classes of B-lactam antibacterials?
|
penicillins
cephalosporins monobactam carbapenems |
|
|
what are 5 generations of penicillins and their associated drugs
|
1. natural -> penicillin
2. penicillinase-resistant -> nafcillin 3. aminopenicillin -> ampicillin 4. carboxypenicillin -> ticarcillin 5. ureidopenicillin -> mezlocillin |
|
|
what family of b-lactams are susceptible to penicillinase?
|
Only penicillins... Cephalosporins, monobactams, and carbapenems are not
|
|
|
penicillins method of action
|
binds to and inhibits penicillin binding proteins (PBPs) which are transpeptidases that cross-link peptidoglycans, the final step in cell wall synthesis
|
|
|
clinical use of penicillins
|
gram positives: strep and listeria
Spirochetes: drug of choice for syphilis most anaerobes except B.fragilis rarely for gram negatives |
|
|
what is a potential side effect of penicillin
|
drug-induced coombs positive hemolytic anemia (pen attaches to RBC membrane and serve as haptens against which an antibody response can be initiated)
|
|
|
How is pen G given?
|
IM or IV
|
|
|
treat syphilis with what drug?
|
penicillin
|
|
|
major potential side effect of ampicillin?
|
C. Diff
|
|
|
what does nafcillin cover clinically?
|
staph and strep infections (cellulitis)
only class of penicillins that is active against staph in absence of b-lactamase inhibitor |
|
|
nafcillin mechanism of action
|
binds to PBP and inhibits cell wall synthesis, however it has bulky hydrophobic R group that prevents b-lactamase from leaving beta lactam ring and is therefore a penicillinase-resistant penicillin
|
|
|
prototype carbapenem
|
imipenem
|
|
|
of all ABX, what has the broadest spectrum and is highly beta-lactamase resistant?
|
Imipenem
|
|
|
imipenem is used clinically to cover?
|
empiric coverage of virtually all bacteria, except: MRSA and VRE
|
|
|
SE of imipenem in pt with renal dysfunction
|
seizures
|
|
|
prototype monobactam
|
aztreonam
|
|
|
is imipenem cross allergic with penicillin
|
yes
|
|
|
what b-lactam abx is not cross allergic with penicillin?
|
aztreonam
|
|
|
what are inherently resistant to cephalosporins?
|
enterococci
|
|
|
First generation cephalosporins coverage includes?
|
gram positives (staph and strep); some gram negatives --> used in surgical prophylaxis and cellulitis
|
|
|
what are the 2 subclasses that 2nd gen cephalosporins are used to treat
|
1. respiratory (cefuroxime) has activity against H.influenzae, M.catarrhalis
2. GI/GU (cefotetan) activity against anaerobes, used to treat peritonitis, diverticulitis, and mixed aerobic-anaerobic infections (B.fragilis etc) |
|
|
3rd gen cephalosporins cover what?
|
very broad gram negative coverage, cross BBB, use for meningitis and sepsis
|
|
|
what are 2 side effects of cephalosporins
|
bleeding and disulfiram reactions
|
|
|
methicillin SE
|
interstitial nephritis and rash
|
|
|
MRSA mechanism of resistance
|
alteration in penicillin binding protein
|
|
|
What criteria is used to diagnose Rheumatic fever?
|
JOnes Criteria
|
|
|
What are the 5 major criteria for Jones criteria?
|
1. carditis
2. polyarthritis 3. sydenham's chorea 4. erythema marginatum rash 5. subcutaneous nodules |
|
|
what are the 5 minor criteria of jones criteria?
|
1. fever
2. arthralgia 3. elevated ESR or CRP 4. prolonged PR interval 5. + streptococcal antibody |
|
|
strep pyogenes infections
|
pharyngitis and skin infections (impetigo, erysipelas, cellulitis)
|
|
|
tx of strep pyogenes
|
pen G
|
|
|
how is imipenem degraded and what can be used with it to inhibit this?
|
imipenem is rapidly degraded by renal dehydropeptidase, cilastatin inhibits renal dehydropeptidase
|
|
|
gentamicin (garamycin) mechanism of action
|
aminoglycoside bactericidal antimicrobial -> enters bacteria by O2-dependent active transport, binds to 30S ribosomal subunit, and inhibits protein synthesis by 1. interfering with formation of initiation complex 2. inducing misreading of of mRNA & 3. causing breakup of polysomes
|
|
|
gentamicin is synergistic with beta-lactam ABX? True or False
|
TRUE -> they increase permeability of cell wall to aminoglycosides
|
|
|
clinical use of gentamicin
|
tx of serious gram negative infections... used for synergy with b-lactam abx or vanco for serious gram positive infections
|
|
|
3 major SEs of gentamicin
|
1. irreversible ototoixicity
2. reversible nephrotoxicity (acute tubular necrosis) 3. neruomuscular blockade and resp peralysis due to inhibition of prejunctional release of Ach and postjunctioal sensitivity to Ach |
|
|
Streptomycin is active against
|
mycobacteria (limited use due to ototoxicity) but multi-drug resistant M.tuberculosis has caused new interest
|
|
|
what is related to aminoglycosides that can be used in treating gonorrhea
|
spectinomycin
|
|
|
Doxycyclines mechanism of action
|
tetracycline antimicrobial -binds to 30S ribosomal subunit and prevents access to aminoacyl tRNA to its acceptor site on the mRNA. Must be imported via energy-dependent active transport
|
|
|
Main clinical use of doxycycline
|
1. rickettsial infections (rocky mountain spotted fever) and chlaymdial infections
2. alternative tx for spirochtes (syphilis, lympe dz, leptospirosis) 3. alternative to macrolides and fluoroquinolones for atypical pneumonia 4. tx for multidrug resistand plasmodum falciparum malaria |
|
|
SE of doxycycline
|
GI irritation
Tooth discoloration in kids under 7 Fatty liver in pregnant woman |
|
|
What drug should tetracycline not be given with?
|
penicillin and tetracycyline are antagonistic
|
|
|
Demeclocycline has adverse effect of ?
|
causing nephrogeneic diabetes insipidus by acting as ADH antagnoist - > therefore used to treat SIADH
|
|
|
neomycins mechanism of action is similar to that of what drug
|
gentamicin
|
|
|
what bacteria are inherently resistant to neomycin/gentamicin and why?
|
anaerobes are inherently resistant because they lack the O2-dependent active transport
|
|
|
what are 2 main clinical applications of neomycin
|
1. topical abx for bowel surgery; drug is administered PO and is not well absorbed from GI tract
2. tx of hepatic encephalopathy: decreases amount of bacteria in the gut, therefore decreases ammonia levels in the blood and decreases encephalopathy |
|
|
mechanism of neomycin
|
enters via O2dependent active transport, binds to 30S ribosomal subunit, inhibits protein synthesis
|
|
|
neomycin is rarely active against gram +s, except in combo with
|
b-lactam or vancomycin
|
|
|
clinical use of tetracycline
|
acne
|
|
|
3 ABX - 30S inhibitors
|
buy AT 30 - CELL for 50
A (aminoglycosides-> NAG) T (tetracycline -> Doxy) doxycycline gentamicin neomycin |
|
|
3 ABX - 50S inhibitors
|
chloramphnicol
clindamycin erythromycin |
|
|
2 antimetabolites
|
sulfonamides
trimethoprim |
|
|
mechanism of action of clindamycin
|
binds to 50S subunit of bacterial ribosomes; suprresses protein syntehsis by disrupting formation of 70S initiation complex and by inhibiting amionacyl translocation step of peptide bond synthesis
|
|
|
clinical use of clindamycin
|
gram positive cocci
anaerobes (except C.Diff) |
|
|
what drug is used to treat aspiration pneumonia and lung abscesses
|
clindamycin - over metronizdazole because superior penetration into lung tissue and activity against gram + anaerobes
|
|
|
major and minor SE of clindamycin
|
pseudomembranous colitis
GI irritation |
|
|
clinical use of Linezolid
|
50S protein synthesis inhibitor that acts against highly resistant gram positive organisms such as MRSA and VRE
|
|
|
What are 2 drugs used to treat MRSA & VRE that act via 50S
|
1. linezolid
2. quinupristin/dalfopristin (synercid) |
|
|
Chloramphenicol mechanism of action
|
binds to 50S subunit of bacteria ribosome, blocks peptidyl transferase, stops protein synthesis
|
|
|
clinical uses of chloramphenicol
|
1. 3 types of meninigitis in people intolerant to b-lactams (meningococcal, pneumococcal, h. influenza)
2. topical tx of eye infeciton |
|
|
SE of chloramphenicol
|
1. bone marrow suppression (dose related and reversible) -> due to inhibition of mitochondrial protein synthesis in bone marrow cells
2. aplastic anemia (worst!) idiosyncratic and dose independent 3. gray baby syndrome -> fatal toxicity in neonates |
|
|
Does chloramphenicol cross BBB? placenta?
|
YES to both
|
|
|
protoype macrolide
|
erythromycin
|
|
|
erythromycin mechanism of action
|
macrolide antimicrobial that inhibits protein synthesis by binding reversibly to 50S ribosomal subunit -> inhibits translocation step of protein synthesis where tRNA -amino acid complex moves from acceptor site to peptidyl site on ribosome
|
|
|
erythromycin is the drug of choice for what?
|
cornebacterial infections (diptheria)
|
|
|
name 3 clinical uses of erythromycin
|
1. community acquired pneumonia (mycoplasma and legionella)
2. chlamydial infections 3. strep or pneumo infections in pen-allergic pts 4. corynebacterial infections |
|
|
SE of erythromycin
|
GI effects (Anorexia/n/V)
cholestatic hepatitis |
|
|
s. mutans causes what local infection
|
dental caries
|
|
|
s. intermedius causes what local infection
|
brain or abdominal abscess
|
|
|
S. mutans or S. intermedius can attach to heart valves how?
|
Viridans streptococci have the unique ability to synthesize dextrans from glucose, which allows them to adhere to fibrin-platelet aggregates at damaged heart valves. This mechanism underlies their ability to cause subacute valvular heart disease following their introduction into the bloodstream (e.g., following tooth extraction).
|
|
|
what is a systemic infection caused by strep viridans
|
Subacute bacterial endocarditis
|
|
|
pathophys of dental carries
|
S. mutans binds to pellicle of teeth -> bacteria ferments sugars into lactic acid -> lactic acid demineralizes tooth enamel -> dental carries
|
|
|
pt has meningitis with penicillin allergy - > tx with what drug emperically?
|
chloramphenicol
|
|
|
gray baby syndrome is caused as a side effect of what drug
|
chloramphenicol - liver enzyme (UDP glucoronlytransferase) can't metabolize drug and its stays in body and they turn gray
|
|
|
most common cause of meningitis in 60+ yrs:
|
S. pneumo
gram - rods listeria |
|
|
common causes of pneumonia in 40-65 yrs
|
S. pneumo
H. influenza Legionella |
|
|
common causes of pneumonia in 65+ yrs
|
S. pneumo
gram - rods H. influenza |
|
|
Strep Pneumo evades host by what mechanisms
|
IgA protease
capsule (escapes phagocytosis) |
|
|
tetracycline SE's
|
1. GI upset, teeth discoloration, bone deformity in children, Fnaconi's syndrome (aminoaciduria, phosphaturia, acidosis, gylcosuria); photosensitivity; dizziness
|
|
|
what 2 drugs cause Subacute Bacterial Endocarditis
|
Strep viridans and Enterococci -> colonize valves damaged by Group A strep (rheumatic fever)
|
|
|
on PE you see Janeway lesions - this is pathonemonic of what - what would cause this ?
|
janeway lesions are pathonemonic for infeciton endocarditis
Acute - Staph aureus Subacute -Strep viridans and Enterococci |
|
|
what test differentitates b/w Strep pneumo and Strep viridans
|
optochin
Sensitive = s. pneumo Resistant = s. mutans, intermedius |
|
|
leading infectious agent in osteomyelitis in kids and adults
|
staph aureus
|
|
|
test to differentiate b/w staph saprophyticus and staph epidermidis
|
novobiocin
sensitive = S. epidermidis resistant = S saprophyticus |
|
|
tx of UTI in pt whos gram stain shows coag -, novobiocin resistant
|
TMP-SMX
tx for staph sap UTI or cystitis |
|
|
what infection is caused by indwelling medical devices - and how does this infectious agent do so
|
staph epidermidis
polysaccharide capsule allows adherence to inserted medical devices |
|
|
Pt with endocarditis and recent (30 days) heart valve replacement -> infectious agent is?
|
endocarditis with a prosthetic heart valve
<60 days = S. epi >60 days = Strep viridans |
|
|
what test differentiates GAS and GBS
|
bacitracin
sensitive = GAS (pyogenes) resitant = GBS (agalactiae) |
|
|
do GAS have pili
|
yes!
|
|
|
Virulence factors of GAS
|
1. streptokinase (fibrinolysis)
2. M protein (resists phagocytosis) 3. hyaluronidase (breaks down CT) 4. DNase (digest DNA) |
|
|
what infectious agent will cause an increase in ASO+
|
Strep:
ASO = anti-streptolysin O antibodies |
|
|
infectious agent from skin infection that 3 wks later causes HTN, periorbital edema, and hematuria
|
Strep pyognes infection -> glomerulonephritis (ASO antibodies generated immune complexes that deposit in BM of kidney)
|
|
|
pt presents with "sandpaper" rash that begins on trunk and spreads outward, and a very red tongue -> infectious agent?
|
Strep pyogenes -> scarlet fever
*S. pyogenes pharyngitis causing systemic release of pyrogenic exotoxin A,B,C -> ferver -> rash and strawberry tongue |
|
|
Necrotizing fascitis caused by GAS -> what is the toxin
|
exotoxin B (protease)
|
|
|
3 presentations of GBS
|
neonatal meningitis, neonatal pneumonia, neonatal sepsis
|
|
|
pregnant woman who tests positive for S. agalactiae - how do you treat or do you?
|
yes. prophylaxis (ampicillin)
|
|
|
this infectious agent is the 2nd most common cause of nosocomial infections in the US
|
enterococcus faecalis - all strains resistant to cephalosporins and some to vanco
|
|
|
old man develops UTI after being in hospital for 5 days and being treated with cephalosporins, what is unique about infectious agent?
|
Enterococcus faecalis
grows in 40% bile, capsule prevents bile salt degradation, resistant to cephalosporins and is known to cause UTI, biliary tract infection, and SBE |
|
|
+ quellung reaction is significant for what bacteria?
|
strep pneumo
|
|
|
Asplenic patients are especially susceptible to pneumonia because unable to remove Ab-coated organisms... therefore what would you give them?
|
pneumovax - vaccine with capsular polysaccharides
Strep pneumo |
