Which organism should rapid beta-lactamase testing be performed on before initiating antimicrobial therapy?

Which organism should rapid beta-lactamase testing be performed on before initiating antimicrobial therapy?

• A. Serratia marcescens
• B. Haemophilus influenzae
• C. Staphylococcus epidermidis
• D. Streptococcus pyogenes

Answer: (B)

Beta-lactamase testing is used to quickly identify if the organism can inactivate beta-lactam antibiotics, guiding initial therapy before full susceptibility results are known. Haemophilus influenzae commonly produces beta-lactamase, which cleaves the beta-lactam ring and makes drugs like ampicillin ineffective. A rapid test that detects this enzyme helps clinicians choose an alternative regimen (such as amoxicillin-clavulanate or a cephalosporin) from the start. The other organisms listed are less routinely assessed this way before therapy: some may have other resistance mechanisms, and penicillin remains reliably effective against Streptococcus pyogenes, while beta-lactamase testing is not typically decisive or necessary for them in the same way as with H. influenzae.

Beta-lactamase testing is used to quickly identify if the organism can inactivate beta-lactam antibiotics, guiding initial therapy before full susceptibility results are known. Haemophilus influenzae commonly produces beta-lactamase, which cleaves the beta-lactam ring and makes drugs like ampicillin ineffective. A rapid test that detects this enzyme helps clinicians choose an alternative regimen (such as amoxicillin-clavulanate or a cephalosporin) from the start. The other organisms listed are less routinely assessed this way before therapy: some may have other resistance mechanisms, and penicillin remains reliably effective against Streptococcus pyogenes, while beta-lactamase testing is not typically decisive or necessary for them in the same way as with H. influenzae.