STUDIES ON β-LACTAMASE PRODUCING AND ANTIBACTERIAL ACTIVITY OF CLINICALLY ISOLATED BRANHAMELLA CATARRHALIS

Abstract

Branhamella catarrhalis (B. catarrhalis) belong to the family Neisseriaceae. B. catarrhalis was found in 50 strains from nasopharynx and middle ear secretion.
β-lactamase producing strains were detected by PC G, CEZ acidometric method and nitrocefin chromogenic method.
Sixty-four per cent (32 strains) of clinically isolated B. catarrhalis 50 strains were β-lactamase producing.
The efficacy of seven antibiotics were analyzed by an agar dilution method against clinical isolates consiting β-lactamase positive and negative B. catarrhalis 50 strains.
Both β-lactamase positive and negative strains of B. catarrhalis showed a wide range of MICs with the IO⁶ cells/ml, inoculum.
The MIC values of ampicillin for β-lactamase positive strains ranged from 3.13 to≥100μg/ml, showing its peak at 6.25μg/ml.
While those for β-lactamase negative strains were all less than 3.13μg/ml. The β-lactamase positive B. catarrhalis strains were most sensitive to the cephems (CTRX, CMX), GM and OFLX.