Emergence of extended spectrum beta lactamase mediated resistance in neonatal septicemia

This study was carried out in microbiology department of Gulbarga university, Gulbarga to find out the frequency of extended spectrum beta lactamase (ESbL) producing gram-negative bacilli isolated from neonatal septicemic cases. This study was carried out from Oct 2001 to June 2004. A total of 471 consecutive Gram-negative bacilli were recovered during the study period from blood samples. Extended spectrum beta lactamase detection in gram-negative isolates was carried out by double disk synergistic method on Mueller Hinton agar. A susceptibility disk containing amoxicillin-clavulanate was placed as the inhibitor of beta lactamase in the center of the plate, and cefotaxime, ceftazidime, ceftriaxone and aztreonam disks were placed 30 mm (center to center) from the amoxicillin-clavulanate disk. Enhancement of the zone of inhibition of the oxyimino-lactam caused by the synergy of the clavulanate in the amoxicillin-clavulanate disk was considered as evidence of ESbL production. Escherichia coli ATCC 25922 and K. pneumoniae ATCC 700603 were used as control strains. The frequency of ESbL producing gram-negative bacilli among the neonatal septicemic cases was 22.7%.