Which antibiotics should not be tested or reported for Enterococcus species in routine susceptibility testing?

Which antibiotics should not be tested or reported for Enterococcus species in routine susceptibility testing?

• A. Aminoglycosides
• B. Cephalosporins
• C. Clindamycin
• D. Vancomycin

Answer: (B)

Cephalosporins should not be tested or reported for Enterococcus in routine susceptibility testing because these bacteria have intrinsic resistance to this class. The activity of cephalosporins against Enterococcus is consistently poor, and results would not reliably reflect any clinical benefit or guide effective therapy. Testing them would be misleading, so laboratories omit them from routine panels. In contrast, testing other antibiotics remains clinically meaningful. Aminoglycosides are considered because Enterococcus can exhibit high-level resistance that negates bactericidal synergy with cell-wall–active agents, so checking for this resistance informs combination therapy. Vancomycin is routinely tested due to the serious concern of vancomycin-resistant Enterococcus. Clindamycin testing may be used in certain contexts where susceptibility can influence treatment, though it’s not the primary agent for Enterococcus infections.

Cephalosporins should not be tested or reported for Enterococcus in routine susceptibility testing because these bacteria have intrinsic resistance to this class. The activity of cephalosporins against Enterococcus is consistently poor, and results would not reliably reflect any clinical benefit or guide effective therapy. Testing them would be misleading, so laboratories omit them from routine panels.

In contrast, testing other antibiotics remains clinically meaningful. Aminoglycosides are considered because Enterococcus can exhibit high-level resistance that negates bactericidal synergy with cell-wall–active agents, so checking for this resistance informs combination therapy. Vancomycin is routinely tested due to the serious concern of vancomycin-resistant Enterococcus. Clindamycin testing may be used in certain contexts where susceptibility can influence treatment, though it’s not the primary agent for Enterococcus infections.