38 Questions
What is the main difference between cephamycins and other cephalosporins?
Cephamycins contain a 7-alpha-methoxy group, imparting resistance to extended-spectrum beta-lactamases.
How are cephalosporins classified?
By their generation (1–4).
Which of the following bacteria are cephalosporins in the first-generation usually quite active against?
Gram-positive bacteria
Why are cephalosporins generally less susceptible to beta-lactamase destruction than penicillins?
Because they contain a 7-alpha-methoxy group.
Which of the following best describes the potential nephrotoxicity of cephalosporins?
Both A and B
In terms of in vitro incompatibilities, what is an exception when mixing cephalosporins with other drugs?
Mixing with weak bases such as aminoglycosides
What potential interactions of cephalosporins are similar to those of the penicillin group?
Pharmacokinetic interactions
Which laboratory determinations may be altered by the cephalosporins?
ALP and BUN concentrations
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
What should veterinarians do regarding withdrawal times for cephalosporin products used in animals?
Consult FARAD for withdrawal recommendations
Which type of elimination is appreciable for the newer cephalosporins?
Biliary elimination
What may lead to drug accumulation for newer cephalosporins?
Hepatic insufficiency
Which cephalosporins have exceptions in maintaining effective blood concentrations for 6–8 hours?
Ceftiofur, cefpodoxime, and cefovecin
For which type of infections are first-generation cephalosporins particularly useful?
Soft tissue and bone infections
What is ceftiofur approved for in production animals?
Bovine respiratory disease
For what type of infections is ceftiofur not recommended for use in dogs?
Soft-tissue infections
What infections are cephalosporins particularly useful for treating?
Infections involving bacteria resistant to other antimicrobials
What may arise with the use of cephalosporins?
Both allergic reactions and superinfection
What has been reported due to antimicrobial-induced perturbations in GI flora?
Antimicrobial-induced colitis
Which of the following bacterial species is NOT effectively targeted by second-generation cephalosporins?
Pseudomonas aeruginosa
What is the main difference between third-generation and fourth-generation cephalosporins?
Extended spectrum against gram-positive bacteria
Which of the following is a characteristic of cephamycins in comparison to other second-generation cephalosporins?
Efficacy against Pseudomonas aeruginosa
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
What is the primary target of plasmid-mediated beta-lactamases produced by gram-positive bacteria such as Staphylococcus aureus?
Cephalosporinase hydrolysis
What distinguishes ceftiofur, a third-generation cephalosporin, from other cephalosporins?
Similarity in gram-negative spectrum to first-generation cephalosporins
What bacterial strain is specifically mentioned as a target for ceftiofur, a third-generation cephalosporin?
Mannheimia haemolytica
True or False: Second-generation cephalosporins are generally more resistant to beta-lactamases compared with first-generation drugs.
True
True or False: Third- and fourth-generation cephalosporins have a spectrum that includes Pseudomonas and other problematic coliforms.
False
What role does the 7-aminocephalosporanic acid nucleus play in the structure of cephalosporins?
It determines the spectrum of antibacterial activity
Why are extended-spectrum beta-lactamases considered a challenge for third- and fourth-generation cephalosporins?
They can hydrolyze third- and fourth-generation drugs
What is the mechanism of action of extended-spectrum beta-lactamases (ESBLs)?
They hydrolyze the oxyimino side chain on extended-spectrum cephalosporins.
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.
How are ESBLs detected on susceptibility testing?
Resistance to these drugs but susceptibility to clavulanic acid, tazobactam, or sulbactam.
What is a common route of administration for most cephalosporins in animals?
Intravenous (IV) or intramuscular (IM) injection.
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.
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.
What can be inferred about the pharmacokinetics of cephalosporins from the given text?
They have high volume of distribution indicating extensive tissue distribution.
What is a unique feature of ceftiofur compared to other cephalosporins?
It is metabolized to several active metabolites, contributing substantially to efficacy.
Test your knowledge about the various types of inducible beta-lactamases produced by gram-negative organisms, their mediation by plasmids or chromosomal factors, and their hydrolyzing capabilities on penicillins and cephalosporins. Explore the stability of second- and third-generation cephalosporins against beta-lactamases and the increasing identification of extended-spectrum beta-lactamases (ESBLs) in bacteria.
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