cell wall agents drug chart + hw answers

kuhl antibiotics drug chart exam 1

what determines spectrum

cell-wall penetration/permeability

type of PBP
affinity for the PBP

PBP concentration

how are most cell wall agents destroyed

gastric acid — unless acid-stable or oral ester prodrug

what cell wall agent is acid stable

penicillin VK

which cell wall agents are not renally eliminated

ceftriaxone and nafcillin/oxacillin

resistance mechanisms

beta lactamases (primary), altered PBPs, reduced porin permeability, efflux pumps

what does cross reactivity track

R1 side chain (not beta lactam ring)

what are class effects of beta lactams

severe delayed reactions — SJS, TEN, DRESS, acute generalized exanthematous pustulosis

which drugs have highest incidence of drug-induced immune hemolytic anemia

cefotetan and ceftriazone

what can prolonged use of beta lactams cause

C diff diarrhea, pseudomembranous colitis, increased INR on warfarin

what is the spectrum of natural penicillins

narrow — covers some gram (+), very little gram (-) coverage

what is the biggest weakness of the natural penicillins

highly susceptible to beta lactamases — why every other penicillin class exists

what drug class/drug covers all stages of syphilis

penicillin G benzathine IM (natural penicillin)

what is unique about benzathine and procaine formulations of natural penicillins

repository IM depots — drug is stored and released slowly (once a week to once a month dosing)

which natural penicillin is acid stable

penicillin VK — only PO natural penicillin

which natural penicillin is used for neurosyphilis and why

penicillin G IV — bc IM benzathine does not reach the CNS

what happens when penicillins and probenecid are taken together

tubular secretion blocked → no penicillin excretion → higher penicillin levels

boxed warning for benzathine IM

not for IV use — cardiorespiratory arrest and death

risk of natural penicillins at high doses

seizures — use with caution in seizure patients

what is a caution/risk with penicillin VK

carries a potassium load — can lead to hyperkalemia at high doses in renally impaired → do not use in patients with poor kidney function

what is a reaction that can occur when treating syphilis with a natural penicillin

jarisch-herxheimer — fever/chills hours after first dose

not an allergy

what natural penicillins are not interchangeable for the treatment of syphilis

bicillin CR and bicillin LA — CR has procaine which under-doses the benzathine (so do not use for syphilis)

what is the only recommended syphilis treatment in pregnancy

benzathine penicillin G — desensitize an allergic patient, don’t class switch

what is the spectrum of aminopenicillins

moderate — some gram (+) and improved coverage of gram (-)

still beta lactamase liable unless combined with a beta lactamase inhibitor

what does adding clavulanate or sulbactam do to aminopenicillins

restores coverage of “bugs” that produce beta lactamase and anaerobes — improves overall coverage of the drug

what covers enterococcus faecalis

ampicillin + gentamicin

what does no generation of cephalosporin cover

enterococci

why is the spectrum of aminopenicillins broader than natural penicillins

greater outer-membrane penetration + higher PBP affinity

which aminopenicillin has higher PO bioavailability

amoxicillin > ampicillin

what is a benefit of ampicillin’s poor oral absorbtion

drug stays in the gut → good for GI infections

what is a common reaction with aminopenicillins when given during EBV/mononucleosis

non-allergic maculopapular rash — not an allergy

what is a side effect of amox/clav (augmentin)

cholestatic hepatitis

are aminopenicillins ok in pregnancy

yes — among the preferred antibiotics

what is the spectrum of anti-staphylococcal penicillins

narrow — gram (+) only (no MRSA)

bulky side chain resists penicillinase

do anti-staphylococcal penicillins have MRSA activity

no — penicillinase resistant drugs do not matter bc MRSA is resistant bc of PBP2a

how are nafcillin and oxacillin eliminated

biliary/hepatically

which anti-staphylococcal penicillin is PO

dicloxacillin — take on an empty stomach

what are some side effects of nafcillin/oxacillin

thrombophlebitis, increased AST/ALT, bone marrow suppression (neutropenia)

not bolded in chart so probs don’t need to know

what is a unique side effect of nafcillin

hypokalemia — drug acts like a non-reabsorbable anion at distal tubule → sodium reabsorbed in kidney, potassium excreted in urine

what side effect is more common in anti-staphylococcal penicillins than other penicillins

interstitial nephritis

what does nafcillin induce

CYP3A4 → decrease warfarin INR → loss of anticoagulation

what is the spectrum of zosyn

broad — gram (+), gram (-), pseudomonas, and anaerobes (poorly covers ESBL)

what is zosyn commonly used for

hospital acquired and polymicrobial infections

what does zosyn poorly cover

ESBL producers

why is zosyn given as extended/prolonged infusions

because it is time-dependent killing — want to raise %fT>MIC

what component of zosyn is renal dose adjustment based on

piperacillin

how much of piperacillin goes through biliary excretion

20-30% (but mainly renal secretion)

what effect does zosyn have on coagulation

causes prolonged bleeding time and platelet dysfunction — independent of warfarin use

what antibiotic can cause cholestatic jaundice and superinfection

zosyn

what is a caution for zosyn’s formulation

high sodium load — use caution in heart failure or patients with sodium restriction

what drug combined with zosyn can cause increased nephrotoxicity

vancomycin

what are interactions with piperacillin

warfarin — increased bleeding risk

vecuronium — prolonged neuromuscular blockade

methotrexate — increased toxicity

what is the spectrum of pivmecillinam

narrow — gram (-) enterobacterales only

what is pivmecillinam used for

uncomplicated UTI only

what is the structure of pivmecillinam

pivaloyl ester prodrug — hydrolyzed into mecillinam for oral absorption

what PBP does pivmecillinam bind

PBP2 — different than every other penicillin

what are serious/rare AEs of pivmecillinam

SJS, TEN, DRESS, acute generalized exanthematous pustulosis

contraindications for pivmecillinam

primary or secondary carnitine deficiency — pivaloyl ester depletes carnitine (already don’t have enough in your body and now its taking even more)

porphyria

what is the spectrum of sulbactam/durlobactam

narrow — acinetobacter baumannii-calcoaceticus complex (ABC) only

what does sulbactam/durlobactam treat

hospital-acquired and ventilator-associated pneumonia (HABP/VABP) caused by ABC complex

describe the different components of sulbactam/durlobactam

sulbactam — active antibacterial agent

durlobactam — beta lactamase inhibitor

what monobactam is new as of 2025

aztreonam/avibactam

what is the spectrum of monobactams

gram (-) bacilli only — no (+) or anaerobic activity

what is the niche of monobactams

beta lactam that can be used in severe penicillin allergy

describe the components of aztreonam/avibactam

avibactam — covers serine beta lactamases

aztreonam — stable to metallo-beta lactamases

targets MBL producers

what about the structure of monobactams make them stable to beta lactamases and non-cross reactive

monocyclic ring (no fused second ring)

what is a unique formulation of monobactams

inhalation — for cystic fibrosis

monobactam side effects

phlebitis, increased liver enzymes, thrombocytopenia, GI hemorrhage, hepatitis, oto and nephrotoxicity, angioedema

what is a major, common (14.5%) side effect of aztreonam/avibactam

liver injury — monitor LFTs

what allergy are monobactams not okay to use in

ceftazidime — has an identical side chain, cross-allergy!!!

what can a monobactam + aminoglycoside cause

increased nephro and ototoxicity

what is the spectrum of 1st gen cephalosporins

gram (+) cocci but never enterococci or MRSA, limited gram (-)

which generation of cephalosporins has the best MSSA coverage

1st gen cephalosporins

which 1st gen cephalosporin should be used with caution in patients with history of seizure

cefazolin

what antibiotic should not be given with the BCG vaccine

1st gen cephalosporins — could decrease efficacy of the vax

what is a contraindication for cephalexin

use with dofetilide — ceph inhibits the renal cationic secretion → increase dofetilide conc → torsades

what is the spectrum of 2nd gen cephalosporins

less gram (+), more gram (-) than 1st gen

which 2nd gen cephalosporins are the cephamycins

cefoxitin and cefotetan — only cephalosporins with anaerobic coverage

what are cefoxitin and cefotetan used for

intra-abdominal and gynecologic surgical prophylaxis

which 2nd gen cephalosporin has good CNS penetration

cefuroxime

what is the structure of cefuroxime axetil

oral ester prodrug — tab vs suspension are not bioequivalent

what is a component of some cefuroxime and cefprozil formulations

phenylalanine

which 2nd gen cephalosporin carries a disulfiram like reaction with alcohol

cefotetan

which 2nd gen cephalosporin can increase INR

cefotetan — monitor PT/INR

why can cefotetan cause disulfiram rxn and increased INR

methylthiotetrazole (MTT/NMTT) side chain — inhibits vit K epoxide reductase

which 2nd gen cephalosporin carries a higher risk of hemolytic anemia

cefotetan

which 2nd gen cephalosporin can cause a serum-sickness reaction

cefaclor

what is an important counseling point of cefotetan

avoid alcohol during therapy and for several days after therapy — disulfiram like reaction

what is the spectrum of 3rd gen cephalosporins

broad — gram (+) varies by agent, improved gram (-)

which 3rd gen cephalosporins are anti-pseudomonal

ceftazidime and ceftolozane/tazobactam

what are ceftazidime/avibactam and ceftolozane/tazobactam reserved for

multi-drug resistant gram (-)

how is ceftriaxone excreted

biliary/hepatically

what allows for once daily dosing of ceftriaxone

no dose adjustment (biliary excretion not renal) + long half life

which 3rd gen cephalosporins are ester prodrugs

cefpodoxime proxetil and cefuroxime axetil

what are the conditions contraindicated on the label in neonates for ceftriaxone

1. <28 days old receiving (or expecting) calc containing IV solutions — fatal lung/kidney precipitate

2. hyperbilirubinemic neonates — kernicterus

how is ceftriaxone used in practice in neonates

avoided in those receiving calcium or elevated bilirubin

which cephalosporin is used in neonates when ceftriaxone must be avoided

cefepime

what is an absolute no in ceftriaxone administration

co-adminstered with calcium containing IV solution through a Y site

what is the spectrum for 4th gen cephalosporins

broad — gram (+) and gram (-) including pseudomonas

what is the niche for 4th gen cephalosporins

febrile neutropenia and nosocomial pneumonia

what is zidebactam

diazabicyclooctane — binds PBP2, so part of its effect is beta lactamse independent