Selective agents and Campylobacter jejuni In selective media for isolating Campylobacter jejuni from stool, which of the following chemotherapeutic agents are typically included at low levels to suppress competing flora without inhibiting Campylobacter growth?

Introduction / Context:
Campylobacter jejuni is a fastidious, microaerophilic pathogen frequently isolated from diarrheal stool. Because stool contains abundant competing flora, selective media incorporate antimicrobial agents that inhibit commensals while allowing C. jejuni to grow.

Given Data / Assumptions:

• Common selective formulations include Skirrow, Butzler, and Campy-BAP media.
• These media often contain vancomycin, polymyxin B (or colistin), and trimethoprim among other agents (for example, amphotericin B, cephalothin depending on recipe).
• Campylobacter jejuni exhibits relative resistance to these agents at the concentrations used in the media.

Concept / Approach:
The question asks which agents “may affect” recovery. In practice, they are deliberately added to affect the mixed microbiota by suppressing them, yet they do not significantly inhibit Campylobacter at selective doses. Therefore, all three named agents are part of standard Campylobacter selective supplements. The best match is “All of these.”

Step-by-Step Solution:
Recall standard selective supplement components for Campylobacter media.Match listed drugs: vancomycin (targets Gram-positives), polymyxin (targets many Gram-negatives), trimethoprim (blocks folate pathway; low impact on Campylobacter at used doses).Conclude that all are used to shape the flora and support Campylobacter recovery.Choose “All of these.”

Verification / Alternative check:
Commercial dehydrated media inserts list these antimicrobials in Campylobacter selective supplements; recovery is improved versus nonselective plates.

Why Other Options Are Wrong:

• D: “None of these” is false; these agents are intentionally included.
• Any single-agent choice is incomplete because typical recipes use a combination.

Common Pitfalls:
Assuming every antimicrobial in a medium targets the pathogen; in selective media, additives primarily suppress competitors without harming the target organism.

Final Answer:
All of these