Gram-Negative Bacterial Beta-Lactamases Quiz

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What is the main difference between cephamycins and other cephalosporins?

Cephamycins are classified by generation (1–4).

Cephamycins contain a 7-alpha-methoxy group, imparting resistance to extended-spectrum beta-lactamases. (correct)

Cephamycins are more effective against gram-negative bacteria.

Cephamycins have a broader spectrum of activity.

How are cephalosporins classified?

By their generation (1–4). (correct)

By their pharmacokinetic characteristics.

By their resistance to beta-lactam destruction.

By their source (natural vs semisynthetic) and spectra.

Which of the following bacteria are cephalosporins in the first-generation usually quite active against?

Gram-positive bacteria (correct)

Enterococcus spp

Anaerobic bacteria

Gram-negative bacteria

Why are cephalosporins generally less susceptible to beta-lactamase destruction than penicillins?

Because they contain a 7-alpha-methoxy group. Signup and view all the answers

Which of the following best describes the potential nephrotoxicity of cephalosporins?

Both A and B Signup and view all the answers

In terms of in vitro incompatibilities, what is an exception when mixing cephalosporins with other drugs?

Mixing with weak bases such as aminoglycosides Signup and view all the answers

What potential interactions of cephalosporins are similar to those of the penicillin group?

Pharmacokinetic interactions Signup and view all the answers

Which laboratory determinations may be altered by the cephalosporins?

ALP and BUN concentrations Signup and view all the answers

In the US, under what circumstances is extralabel drug use (ELDU) of cephalosporins prohibited?

When deviations from the approved dose and treatment duration are made Signup and view all the answers

What should veterinarians do regarding withdrawal times for cephalosporin products used in animals?

Consult FARAD for withdrawal recommendations Signup and view all the answers

Which type of elimination is appreciable for the newer cephalosporins?

Biliary elimination Signup and view all the answers

What may lead to drug accumulation for newer cephalosporins?

Hepatic insufficiency Signup and view all the answers

Which cephalosporins have exceptions in maintaining effective blood concentrations for 6–8 hours?

Ceftiofur, cefpodoxime, and cefovecin Signup and view all the answers

For which type of infections are first-generation cephalosporins particularly useful?

Soft tissue and bone infections Signup and view all the answers

What is ceftiofur approved for in production animals?

Bovine respiratory disease Signup and view all the answers

For what type of infections is ceftiofur not recommended for use in dogs?

Soft-tissue infections Signup and view all the answers

What infections are cephalosporins particularly useful for treating?

Infections involving bacteria resistant to other antimicrobials Signup and view all the answers

What may arise with the use of cephalosporins?

Both allergic reactions and superinfection Signup and view all the answers

What has been reported due to antimicrobial-induced perturbations in GI flora?

Antimicrobial-induced colitis Signup and view all the answers

Which of the following bacterial species is NOT effectively targeted by second-generation cephalosporins?

Pseudomonas aeruginosa Signup and view all the answers

What is the main difference between third-generation and fourth-generation cephalosporins?

Extended spectrum against gram-positive bacteria Signup and view all the answers

Which of the following is a characteristic of cephamycins in comparison to other second-generation cephalosporins?

Efficacy against Pseudomonas aeruginosa Signup and view all the answers

Why are third- and fourth-generation cephalosporins designed to be increasingly resistant to beta-lactamases?

To extend the spectrum of activity against gram-negative bacteria Signup and view all the answers

What is the primary target of plasmid-mediated beta-lactamases produced by gram-positive bacteria such as Staphylococcus aureus?

Cephalosporinase hydrolysis Signup and view all the answers

What distinguishes ceftiofur, a third-generation cephalosporin, from other cephalosporins?

Similarity in gram-negative spectrum to first-generation cephalosporins Signup and view all the answers

What bacterial strain is specifically mentioned as a target for ceftiofur, a third-generation cephalosporin?

Mannheimia haemolytica Signup and view all the answers

True or False: Second-generation cephalosporins are generally more resistant to beta-lactamases compared with first-generation drugs.

True Signup and view all the answers

True or False: Third- and fourth-generation cephalosporins have a spectrum that includes Pseudomonas and other problematic coliforms.

False Signup and view all the answers

What role does the 7-aminocephalosporanic acid nucleus play in the structure of cephalosporins?

It determines the spectrum of antibacterial activity Signup and view all the answers

Why are extended-spectrum beta-lactamases considered a challenge for third- and fourth-generation cephalosporins?

They can hydrolyze third- and fourth-generation drugs Signup and view all the answers

What is the mechanism of action of extended-spectrum beta-lactamases (ESBLs)?

They hydrolyze the oxyimino side chain on extended-spectrum cephalosporins. Signup and view all the answers

What is a notable feature of the standard cephalosporins in terms of their penetration into the central nervous system?

They poorly penetrate the ocular humor. Signup and view all the answers

How are ESBLs detected on susceptibility testing?

Resistance to these drugs but susceptibility to clavulanic acid, tazobactam, or sulbactam. Signup and view all the answers

What is a common route of administration for most cephalosporins in animals?

Intravenous (IV) or intramuscular (IM) injection. Signup and view all the answers

What is a notable feature of cefovecin in terms of its elimination half-life in cats?

It has a long elimination half-life of 5.5-6.9 days. Signup and view all the answers

What does it mean that third- or fourth-generation cephalosporins are often able to penetrate the blood-brain barrier?

They achieve good penetration into the CSF. Signup and view all the answers

What can be inferred about the pharmacokinetics of cephalosporins from the given text?

They have high volume of distribution indicating extensive tissue distribution. Signup and view all the answers

What is a unique feature of ceftiofur compared to other cephalosporins?

It is metabolized to several active metabolites, contributing substantially to efficacy. Signup and view all the answers