Detection of Plasmid Borne Extended Spectrum Beta Lactamase Enzymes from Blood and Urine Isolates of Gram-Negative Bacteria from a University Teaching Hospital in Nigeria

The present study investigated the occurrence of Extended Spectrum Beta Lactamase (ESBL) enzyme in clinical isolates of Escherichia coli and Klebsiella pneumoniae from Enugu, Nigeria. Ninety-nine clinical strains of gram- negative bacteria comprising of E. coli (69) and K. pneumoniae (30) were isolated from urine and blood samples from Enugu State University Teaching Hospital (ESUTH), Enugu, Nigeria, from April-July 2008. The presence of ESBL was determined using the Double Disc Synergy Test (DDST). To determine whether the ESBL present is plasmid or chromosomally mediated, positive ESBL isolates were grown in 0.1% acridine orange for 18-24 h. The transfer of resistance marker from ESBL-positive strains of Gram-negative organisms to a non-ESBL strain of E. coli was evaluated via conjugation. The ESBL production was detected in 17 (56.6%) isolates of Klebsiella pneumoniae and 41 (59.4%) isolates of E. coli. The results of our study showed that the prevalence of ESBL in ESUTH was high and was plasmid-mediated. Stable transfer of resistance marker of 8 (47%) ESBL-positive E. coli and 1 ( 14.3%) K. pneumoniae to the non-ESBL recipient strain was observed after trans-conjugation. There is apparently high prevalence of ESBL producing strains of E. coli and K. pneumoniae in present study environment and the enzyme genes are plasmid mediated.