Characterization of extended spectrum β-lactamase producing bacteria isolated from urinary tract infections

Abstract

Background: A unique challenge for clinical microbiologists, clinicians, infection control professionals is to deal with extended-spectrum β-lactamase (ESBL) producing pathogens. Objectives: The study was aims to isolate ESBL producing bacteria from urine samples of Urinary Tract Infection (UTI)-patients and to analyses their phenotypic and genotypic characteristics. Methods: A total of 90 urine samples from UTI patients were collected from Enam Medical College Hospital and Gonoshastha Medical College Hospital, Savar, Dhaka, Bangladesh; between May-2012 to August-2012. A total 75gram negative isolates were retrieved and screened for ESBL production by the Double Disk Diffusion Synergy Test (DDST). Isolates with ESBL phenotype were further characterised by antibiotic susceptibility testing, PCR and sequencing of β-lactamase genes. Results: Cultural and biochemical assay combined with 16S rRNA gene based phylogenetic identification confirmed that Escherichia spp. were predominant pathogens associate with UTI (41%), and the rest were distributed within the genus Enterobacter spp. 26%, Klebsiella spp. 21%, and Pseudomonas spp.10%. Total 31 isolates were phenotypically confirmed as ESBLs through DDST. The multidrug resistant (MDR) and ESBL producing bacteria showed high resistance to cefotaxime (96%), cefixime (90%) and imipenem (32%). PCR reaction was carried out targeting the genes blaTEM, blaCTX. Dominant ESBL class was CTX-M (65%) followed by TEM (52%). All ESBL isolates except 7 possesses multiple plasmids indicating possibility of both chromosomal and plasmid inheritance of ESBLs. Conclusions: This study shows a high prevalence of ESBL producing MDR in UTI patients among these two hospitals of Bangladesh indicating the necessity of alternative therapeutic intervention.