Which group of organisms should be screened for B-lactamase production prior to susceptibility testing?

The screening for β-lactamase production is essential for Enterococcus spp. because these organisms are known to produce various types of β-lactamases that can inactivate β-lactam antibiotics. This characteristic allows them to exhibit resistance to the usual penicillins and can significantly affect treatment outcomes. Therefore, it is critical to test for β-lactamase production in Enterococcus spp. before conducting susceptibility testing to ensure appropriate antibiotic choices and to understand the organism’s resistance mechanisms.

In contrast, Streptococcus pneumoniae is not typically associated with β-lactamase production, and susceptibility testing is generally already well-established for this organism based on its known susceptibility profile. Group B streptococci also do not commonly produce β-lactamases and are typically susceptible to penicillin. Planococcus spp., while less commonly encountered in clinical settings, do not generally exhibit β-lactamase production and are not a primary focus for screening in the context of β-lactam susceptibility testing. Thus, the emphasis on Enterococcus spp. is critical for guiding effective antimicrobial therapy.