NAPLEX — Infectious Disease flashcards

10 of 80 cards free to study here · 1 topic · the whole deck is built into Willys

Antibacterial spectra, toxicities and interactions, C. difficile, empiric UTI, pneumonia, meningitis and neutropenic fever, dental prophylaxis, STIs and doxy-PEP, antifungals, antivirals, HIV treatment and PrEP, and TB drug toxicities — with no doses.

Get the app All PTCB PTCE / NAPLEX decks

Learn deck · part of PTCB PTCE / NAPLEX · written against: Top-drug lists and federal pharmacy law as of 2026; PTCE content outline effective 6 January 2026. Updated 2026-10-10.

Study the free sample

10 cards from the deck as they are. Flip, rate yourself, filter by topic; your progress stays in this browser.

The 10 sample cards as a list

Which pharmacodynamic parameter best predicts beta-lactam efficacy, and how does that shape the way they are infused?

Time above the MIC (the fraction of the dosing interval that free drug stays above the minimum inhibitory concentration). This is why beta-lactams are given frequently or as extended or continuous infusions rather than as large infrequent doses.
Infectious Disease › Beta-Lactams
How does MRSA resist beta-lactams, and which cephalosporin is still active against it?

The mecA gene encodes an altered penicillin-binding protein, PBP2a, with low affinity for almost all beta-lactams. Ceftaroline binds PBP2a and is the classic anti-MRSA cephalosporin; ceftobiprole (US-approved in 2024) is also active against MRSA.
Infectious Disease › Beta-Lactams
A patient with a non-severe amoxicillin allergy needs a cephalosporin. What drives the risk of cross-reactivity?

Cross-reactivity is low overall and depends mainly on similar R1 side chains, not the shared beta-lactam ring. Cephalexin and cefadroxil share a side chain with amoxicillin and ampicillin, so a cephalosporin with a dissimilar side chain, such as cefazolin or ceftriaxone, is preferred.
Infectious Disease › Beta-Lactams
A patient on valproate for epilepsy is started on meropenem. What is the danger?

Carbapenems cause a rapid, profound fall in valproate levels that raising the valproate dose may not overcome, risking breakthrough seizures. The combination is avoided, and another antibiotic or antiseizure drug is used.
Infectious Disease › Beta-Lactams
Which important gram-negative pathogens are not covered by ertapenem, unlike other carbapenems?

Pseudomonas aeruginosa and Acinetobacter, and it is also weak against enterococci. Ertapenem suits community-acquired infections, but meropenem or imipenem is needed when Pseudomonas is a concern.
Infectious Disease › Beta-Lactams
Why is ceftriaxone avoided in jaundiced newborns, and which IV fluids must never be given with it in neonates?

Ceftriaxone displaces bilirubin from albumin, raising the risk of bilirubin encephalopathy in hyperbilirubinemic neonates. In neonates it is also contraindicated with calcium-containing IV solutions, because fatal ceftriaxone–calcium precipitates have formed in lungs and kidneys.
Infectious Disease › Beta-Lactams
Why is aztreonam usually safe in a patient with an IgE-mediated penicillin allergy, and which exception applies?

Aztreonam is a monobactam with very little cross-reactivity with penicillins. The exception is a ceftazidime allergy, because aztreonam and ceftazidime share an identical side chain.

Watch out: aztreonam covers only aerobic gram-negative bacteria.
Infectious Disease › Beta-Lactams
Which beta-lactams have activity against Pseudomonas aeruginosa?

Piperacillin–tazobactam, cefepime, ceftazidime, aztreonam, meropenem and imipenem (plus newer combinations such as ceftolozane–tazobactam). Ceftriaxone, cefazolin and ertapenem do not cover it.

Example: in high-risk febrile neutropenia, one of these (cefepime, piperacillin–tazobactam or meropenem) is started within the first hour, without routine vancomycin.
Infectious Disease › Beta-Lactams
An older patient with worsening kidney function becomes confused and develops myoclonus while on cefepime. What should be suspected?

Cefepime-induced neurotoxicity, including encephalopathy and nonconvulsive status epilepticus, which is more likely when the dose is not adjusted for renal function. Stopping the drug or adjusting for kidney function usually reverses it.
Infectious Disease › Beta-Lactams
Why must penicillin G benzathine never be given intravenously?

It is a long-acting intramuscular suspension, and inadvertent IV injection has caused cardiorespiratory arrest and death. It carries a boxed warning restricting it to deep IM injection.
Infectious Disease › Beta-Lactams

Unlock the whole deck

You are studying a free 10-card sample. All 80 cards of NAPLEX — Infectious Disease, the other 12 PTCB PTCE / NAPLEX decks, and spaced-repetition scheduling are built into Willys. 14-day free trial, then $14.99 a year.

Get the app

In Willys, tap Exam Library at the top of your Decks (or Browse Exam Library… under the + button), find the exam on its shelf or by search, tick it and tap Add.

More PTCB PTCE / NAPLEX decks

Top Drugs: Brand ↔ Generic, Part 1 Top Drugs: Brand ↔ Generic, Part 2 Interactions, Adverse Effects & Counseling Cloze: Top Drugs & Counseling PTCB Practice: Sig Codes, Law & Safety Practice Questions: PTCB & Top Drugs Cardiovascular and Renal Endocrine and GI Pulmonary, Oncology and Immunology CNS, Psychiatry and Pain Practice Questions, Part 1 Practice Questions, Part 2

← All PTCB PTCE / NAPLEX decks, with the study guide and topic outline.

About these cards

Review status: Second-reader reviewed, with corrections applied.

Checked against:

NABP NAPLEX competency statements (topic outline only; no text copied)
Checked against FDA prescribing information and standard pharmacotherapy references (reference only; no text copied)
Checked against the IDSA/SHEA C. difficile guideline (2021 focused update), the ATS/IDSA community-acquired pneumonia guideline (2019) and its ATS update (2025), the IDSA/ESCMID uncomplicated cystitis and pyelonephritis guideline (2010), the AAAAI/ACAAI drug allergy practice parameter (2022), the ASHP/IDSA/PIDS/SIDP vancomycin monitoring consensus (2020), CDC STI Treatment Guidelines (2021) and doxy-PEP recommendations (2024), CDC PrEP guidance, the 2021 AHA scientific statement on endocarditis prophylaxis, and ATS/CDC/IDSA tuberculosis treatment guidance (reference only; no text copied)
Neutropenic fever example checked against the IDSA 2010 fever and neutropenia guideline as summarized in a 2019 US book chapter (Baluch and Shewayish, "Neutropenic Fever", in Velez et al., eds, Infections in Neutropenic Cancer Patients; PMC7120136), the ASCO/IDSA 2018 outpatient fever and neutropenia guideline, and the eviQ (Cancer Institute NSW) neutropenic fever protocol (reference only; no text copied).

These are independent study notes written for Willys. They are not official exam material, may contain mistakes, and are no substitute for your course, your teacher or the exam owner's own publications. Found an error? Tell us — corrections ship as a new version of the deck.

Not clinical guidance. These cards prepare you for an exam. Never use them to make decisions about a patient's care: follow current guidelines, prescribing information and your institution's policies. The decks contain no doses.

Use of these pages is covered by our Terms of Use.