Chapter 22: ID I - Background and Antibacterials by Class Flashcards
Gram positive organisms have a ___ cell wall and stain ___ from the ____ stain
Gram negative organisms have a ___(thick or thin) cell wall and take up ____ counterstain, resulting in what color
thick
dark purple or blueish
Crystal violet
thin
Safranin
Pink or reddish
Which organisms are gram-positive cocci clusters
Staphylococcus spp. (including MRSA and MSSA)
Which organism is a gram-positive rod
Listeria monocytogenes
Which organisms are gram-positive anaerobes
- Peptostreptococcus
- Actinomyces spp.
- Clostridium spp
Which organisms are gram-positive cocci in pairs and chains
- Strep pneumoniae (diplococci)
- Streptococcus spp (including Strep. pyogenes)
- Enterococcus spp (including VRE)
Which organism is a gram-negative cocci
Neisseria spp
Which organisms are gram-negative anaerobes
- Bacteroides fragilis
- Prevotella spp
Which organisms are gram-negative coccobacilli
- Acinetobacter baumannii
- Bordetella pertussis
- Moraxella catarrhalis
Which organisms are gram-negative rods that colonize the gut (enteric)
- Proteus mirabilis
- E. coli
- Klebsiella spp
- Serratia spp
- Enterobacter cloacae
- Citrobacter spp
Which organisms are gram-negative rods that do not colonize the gut
- Pseudomonas aeruginosa
- H. influenzae
- Providencia spp
Which organisms are curved or spiral shaped gram-negative rods
- H. pylori
- Campylobacter spp
- Treponema spp
- Borrelia spp
- Leptospira spp
The higher the MIC value, the more ____-spectrum it is
The lower the MIC value, the more ____-spectrum it is
narrow (choose drugs with high MIC)
broad
What is intrinsic resistance
the resistance is natural to the organism
ex: E.coli is resistant to vanco bc this antibiotic is too large to penetrate the bacterial cell wall of E.coli
What is selection pressure
resistance occurs when antibiotics kill off susceptible bacteria, leaving behind more resistant stains to multiply
What is enzyme inactivation
enzymes produced by bacteria break down the antibiotic
What are extended-spectrum beta-lactamases (ESBLs)
beta-lactamases that can break down all penicillins and most cephalosporins
What are carbapenem-resistant Enterobacteriaceae (CRE)
they are multidrug-resistant (MDR) gram-negative organisms (e.g, Klebsiella spp., E. coli) that produce enzymes (e.g., carbapenemase) capable of breaking down penicillins, most cephalosporins, and carbapenems
What is collateral damage
Unintended consequences of antibiotic use. Antibiotics kill normal, healthy GI flora along with the pathogens they are targeting, resulting in overgrowth or organisms that are resistant to the drug and can lead to superinfections, such as C. diff
Common resistant pathogens
- Remember: Kill Each And Every Strong Pathogen*
- Klebsiella pneumoniae (ESBL, CRE)
- E. coli (ESBL, CRE)
- Acinetobacter baumannii
- Enterococcus faecalis, Enterococcus faecium (VRE)
- Staphylococcus aureus (MRSA)
- Pseudomonas aeruginosa
Which antibiotics inhibit folic acid synthesis
- Sulfonamides
- Timethoprim
- Dapsone
Which antibiotics are cell wall inhibitors
- BL (penicillins, cephalosporins, carbapenems)
- Monobactams (aztreonam)
- Vancomycin, dalbavancin, telavancin, oritavancin
Which antibiotics inhibit protein synthesis
- Aminoglycosides
- Macrolides
- Tetracyclines
- Clindamycin
- Linezolid, tedizolid
- Quinupristin/dalfopristin
Which antibiotics are cell membrane inhibitors
- Polymyxins
- Daptomycin
- Telavancin
- Oritavancin
Which antibiotics are DNA/RNA inhibitors
- Quinolones (DNA gyrase, topoisomerase IV)
- Metronidazole, tinidazole
- Rifampin
Which antibiotics are hydrophilic
Lipophilic?
- BL
- AMG
- Glycopeptides
- Daptomycin
- Polymyxins
- Quinolones
- Macrolides
- Rifampin
- Linezolid
- Tetracyclines
Lipophilic antibiotics have a (large/small) volume of distribution, giving them (excellent/poor) tissue penetration, whereas hydrophilic antibiotics have a (large/small) volume of distribution, giving them (excellent/poor) tissue penetration
Lipophilic - large Vd = excellent tissue penetration
Hydrophilic - small Vd = poor tissue penetration
Hydrophilic antibiotics are eliminated ____
Lipophilic antibiotics are metabolized ____
renally, possibly causing nephrotoxicity or accumulation of drug
hepatically, possibly causing hepatotoxicity and DDI
Hydrophilic antibiotics have (high/low) intracellular concentrations, meaning they (are/are not) active against atypical pathogens.
Lipophilic antibiotics have (high/low) intracellular concentrations, meaning they (are/are not) active against atypical pathogens.
Hydrophilic - low intracellular concentrations; they are not active against atypical pathogens
Lipophilic - high intracellular concentrations; they are active against atypical pathogens
(Hydrophilic or lipophilic) antibiotics have increased clearance and/or distribution in sepsis
Hydrophilic (consider loading doses and aggressive dosing in sepsis)
Hydrophilic agents have (excellent/poor) bioavailability.
Lipophilic agents have (excellent/poor) bioavailability.
Hydrophilic- poor
Lipophilic- excellent
Which antibiotic classes have concentration dependent killing
Drugs with concentration dependent killing can be dosed
AMG, quinolones, daptomycin
less frequently and in higher doses to maximize the concentration above the MIC (large dose, long interval)
Which antibiotic class has time-dependent killing
Drugs with time-dependent killing can be dosed
BL
more frequently or administered for a longer duration to maximize the time above the MIC (e.g., extending the infusion time from 30 min to 4 hrs or administering as a continuous infusion)
Beta-lactam MOA
inhibit bacterial cell wall synthesis by binding to penicillin-binding proteins (PCPs), which prevents the final step of peptidoglycan synthesis in bacterial cell walls
Aminopenicillins combined with beta-lactamase inhibitors (clavulanate, sulbactam, and tazobactam) have added activity against
MRSA, gram negative bacteria [e.g., Haemophilius, Neisseria, Proteus, E. coli, & Klebsiella (HNPEK)] & gram-negative anaerobes (B. fragilis)
piperacillin-tazobactam covers
- Gram-positive bacteria (streptococci, MSSA, Enterococci)
- Gram-positive anaerobes (mouth flora)
- more resistant strains of Haemophilius, Neisseria, Proteus, E. coli, & Klebsiella (HNPEK)
- Gram negative anaerobes (B. fragilis)
- Expanded coverage of other GNB, including Citrobacter, Acinetobacter, Providencia, Enterobacter, Serratia (CAPES)
- PsA
Which penicillins are Natural penicillins, brand and route of admin
Penicillin V Potassium
Penicillin G Benzathine (Bicillin L-A) - IM
Not for IV use; can cause cardio-respiratory arrest and death
Which penicillins are aminopenicillins, brand and route
Amoxicillin - tab, susp, cap, chew
Amoxicillin/clavulanate (Augmentin) - tab, susp, chew
Ampicillin - cap, susp, inj
Ampicillin/Sulbactam (Unasyn) - inj
Which penicillins are antistaphylococcal penicillins
When are they preferred
Dicloxacillin, Nafcillin, Oxacillin
MSSA soft tissue, bone and joint, endocarditis and bloodstream infections
Do not require renal dose adj
Penicillin CI
CrCl < 30 mL/min: do not use ER oral forms of amoxicillin and Augmentin or 875 mg strength of Augmentin
Penicillin side effects
Seizures (with accumulation), GI upset, diarrhea, rash (including SJS/TEN)
Which Antistaphylococcal PCN is a vesicant & what should be done if extravasation occurs
vesicant is an agent (such as a chemical weapon) that induces blistering
Nafcillin
Use cold packs and hyaluronidase injections
Which drug can increase the levels of beta-lactams by interfering with renal excretion
Probenacid
All penicillins should be avoided in patients with BL allergy except:
- Treatment of syphilis during pregnancy (all pts)
- HIV patients with poor compliance/follow-up - desensitize and treat with benzathine PCN
Which PCN is first line for strep throat and mild non-purulent skin infections (no abscess)
Penicillin VK
Which PCNs are first line for acute otitis media & dose
Amoxicillin (80-90 mg/kg/day), Augmentin (90 mg/kg/day)
Which PCN is DOC for infective endocarditis ppx before dental procedures & dose
Amoxicillin (2 grams PO x 1, 30-60 min before procedure)
Which PCN is used in H. pylori treatment
Amoxicillin
Which PCN is first line for sinus infections (if an antibiotic is indicated)
Augmentin (use the lowest dose of clavulanate to decrease diarrhea)
Which PCN is DOC for syphilis & dose
PCN G Benzathine 2.4 million units IM x1
As a class, cephalosporins are not active against
Enterococcus spp
First-generation cephalosporins
Cefazolin
Cephalexin
Second-generation cephalosporins
Cefuroxime
Cefotetan (Cefotan)
Third-generation group 1 cephalosporins
Third–generation group 2 cephalosporin & brand name
Cefdinir
Ceftriaxone (no renal adj)
Cefotaxime
Ceftazidime (Fortaz)
Fourth-generation cephalosporin & coverage
Cefepime
broad gram-negative activity (PsA)
Fifth-generation cephalosporin & brand & coverage
Ceftaroline fosamil (Teflaro)
similar broad gram-negative activity to ceftriaxone, but broad-gram positive activity
It is the ONLY BL THAT COVERS MRSA
Ceftriaxone CI
hyperbilirubinemic neonates (causes biliary sludging, kernicterus); concurrent use with calcium-containing IV products in neonates < / = 28 days old
Cefotetan contains a side chain, which can increase the risk of ____ and cause a ____ reaction
bleeding
disulfuram-like reaction with alcohol ingestion
Cephalosporin SE
Seizures (with accumulation), GI upset, diarrhea, rash
Which cephalosporin comes as a chewable tab
Cefixime
Ceftazidime/avibactam covers some
CRE
Which cephalosporins should be separated by 2 hours from short-acting antacids
Cefuroxime, cefpodoxime
Which cephalosporin is commonly used for skin infections (MSSA) and strep throat
Cephalexin (outpatient)
Which cephalosporin is commonly used in acute otits media
Cefuroxime
Which cephalosporins are commonly used in CAP
Outpatient (oral):
Cefuroxime, Cefdinir
Inpatient (parenteral):
Ceftriaxone, Cefotaxime
Which cephalosporins are commonly used in surgical ppx
Cefazolin, Cefotetan & cefoxitin (colorectal procedures)
Which cephalosporins are commonly used in sinus infection (if antibiotic is indicated)
Outpatient (oral):
Cefuroxime, Cefdinir
Which cephalosporins are commonly used in spontaneous bacterial peritonitis and pyelonephritis
Ceftriaxone, Cefotaxime
Which two cephalosporins are active against PsA
Ceftazidime
Cefepime
Carbapenems are very broad-spectrum antibiotics that are generally reserved for:
They do not have coverage for
MDR gram-negative infections (active against ESBL-producing bacteria, & PsA, except ertapenem)
atypical pathogens, MRSA, VRE, C. diff, Stenotrophomonas
Ertapenem does not have coverage for
PsA, Acinetobacter, or Enterococcus (remember PEA)
All carbapenems are ___ only
IV
Common uses of carbapenems
- Polymicrobial infections (e.g., diabetic foot infection)
- Empiric therapy when resistant organisms are suspected
- Resistant PsA or Acinetobacter infections (except ertapenem)
Which drug is a monobacam & brand name
When can it be used
Coverage?
Aztreonam (Azactam)
When a BL allergy is present since it makes cross-reactivity with a BL allergy unlikely
G- organisms, including PsA
No gram + or anaerobic activity
Aminoglycosides coverage
GNB (including PsA)
Gentamycin and streptomycin are used for synergy in combination with a BL or vanco when treating G+ infections
Traditional dosing of AMG uses ___ doses ___ frequently
Extended interval dosing of AMG uses ___ doses ___ frequently
lower doses more frequently (e.g., Q8H if renal function is normal)
higher doses (to attain higher peaks) less frequently (e.g, once daily if renal function is normal)
Extended interval dosing has been shown to decrease nephrotoxicity and cost (but it is not clinically superior to traditional dosing)
Which drugs are AMGs
Gentamycin, tobramycin, amikacin, streptomycin, plazomicin
If patients are underweight, use ___ for AMG dosing
If patients are obese, use ___ for AMG dosing
TBW
AdjBW
Traditional IV dosing of gentamicin and tobramycin
Renal dose adjustment for CrCl >/= 60 mL/min in AMG traditional dosing
1-2.5 mg/kg/dose
Q8H