Clinical significance and molecular characterization of Extended Spectrum -Lactamases (ESBLs) producing escherichia coli associated with Urinary tract infection in Bangladesh

Abstract

Patients having urinary tract infections (UTIs) with multidrug resistance bacteria suffer from various complications. This is due to -lactamase-production by certain group of bacteria. This study was undertaken to explore the molecular mechanisms of drug resistance caused by ESBL-producing Escherichia coli isolated from UTI patients in the Sylhet community of Bangladesh. A total of 100 urine samples from symptomatic UTI patients were used in this study. Twenty three isolates were found to be Klebsiella, which were discarded. Remaining 77 isolates were identified as Escherichia coli by standard methods in the laboratory. Of these isolates, 25 were further confirmed as ESBL-producing Escherichia coli by double disc-diffusion synergy test and these 25 were used in the present study. The patients’ age ranged from 4 to 60 years. The highest age incidence of UTI patients was 21-30 years (28%), followed by 31-40 years (20%), 50 years and above (19%) and 41-50 years (15%). The antibiotic susceptibility test for non-ESBL-producing organisms showed 100% sensitivity to imipenem (IMP) and meropenem (MPM). There were multidrug resistance (MDR) to amoxyclavulanic acid (AMC, 30%), ceftazidime (CAZ, 40%), ceftriaxone (CRO, 35%) and ciprofloxacin (CIP, 60%). Some isolates were sensitive to AMC (70%), CAZ (60%), CRO (65%) and CIP (40%). The ESBL-producing isolates were also 100% sensitive to carbepenems and some were resistant to AMC (76%), CAZ (55%), CRO (66%) and CIP (73%). Serogrouping showed that all ESBL isolates were heterogeneous and did not match with non-ESBL isolates. Nine ESBL isolates could not be typed and they were designated as untypeable. Plasmid profile analysis was done both for ESBL and non-ESBL producing isolates. The plasmid profile showed both ESBL and non-ESBL exhibits high molecular weight plasmids (>140 MDa), which were 68 and 75% respectively. These findings suggest that both ESBL and non-ESBL-producing isolates harbor large size plasmid, indicating that the isolates carry transmissible plasmids and they are responsible for multidrug resistance (MDR) in Sylhet community. The investigations were further carried out about the detection of genes encoding ESBL types by polymerase chain reactions (PCRs). The ESBL positive strains showed blaCTX-M-1 gene (60%), blaOXA-1 gene (41%) and 45% isolates constituted blaTEM-1 gene. PCRs were also done in all these 20 ESBL isolates for virulent genes. Only 2 isolates showed pilus-associated pylonephritis (pap) genes and one isolate showed afrimbial adhesion (afa) gene. Further data analysis revealed that out of 20, 12 (60%) isolates were having single gene, 7 (35%) isolates had double genes and 1 (5%) isolate had triple gene. Interestingly, it was seen that isolates having single gene (60%) were harboring 140 MDa plasmids. These large-sized plasmids are transmissible in the community of Sylhet District. These results suggest that multidrug resistance (MDR) is probably due to TEM-1 gene harboring 140 MDa plasmids in the community. Pulsed-field gel electrophoresis results showed no clonal relatedness among the ESBL isolates. Same findings were found in non-ESBL-producing isolates. In conclusion, the ESBL uropathogenic E. coli isolates were responsible for multidrug resistance (MDR) in the community of Sylhet Town. They also harbor large sized transmissible plasmids and these plasmids are encoded by genes such as TEM-1, OXA-1 and CTX-M-1. It is CTX-M-1 that constitutes the highest percentage (60%) in the district of Sylhet in Bangladesh.