ABSTRACT
Background: beta-lactam antibiotics have often been used together with vancomycin, and this treatment has been a common combination for long time, beta - lactam-induced vancomycin-resistant methicillin-resistant Staphylococcus aureus [MRSA; BIVR] is a subtype of MRSA, which is otherwise vancomycin susceptible that shows vancomycin resistance in the presence of beta -lactam antibiotics
Objective: In our study, we aimed to characterize and evaluate the antimicrobial profile of BIVR isolated from Mansoura University Hospitals [MUH] and prove the association between usage of fi-lactam antibiotics and BIVR development
Patients and Methods: We studied 40 MRSA strains, identified by detection of MeCA gene and they were selected to be vancomycin sensitive with minimum inhibitory concentration [MIC] [< 2microg/ml] by subjecting these strains to simplified population analysis, p-lactamase activity was tested by nitrocefin test. BIVR strains were subjected to time kill study
Results: eight of 40 MRSA strains isolated from different nosocomial infections in MUH were BIVR [20.0%]. Wound infection is the common infection from which BIVR strains were isolated [75.0]. Only one strain [12.5%] of BIVR strains is J3 lactamase producer, while the majority of non-BIVR strains were fi lactamase producer [93.8%] [P<0.05]
Conclusion: BIVR phenomenon is induced only in the presence of fi-lactam antibiotics, proving that BIVR cells seem to have a low level of fi-lactamase activity compared with that ofnon-BIVR MRSA