Antimicrobial susceptibility and molecular epidemiology of extended -spectrum β -lactamase producing Escherichia coli in Kerman, 2014

Introduction and Objectives: Extended-spectrum beta-lactamases (ESBLs) are the major cause of resistance to beta-lactam antibiotics such as penicillins, cephalosporins, and monobactams. The main objective of this study was to investigate the prevalence, possible types of ESBL genes and antibiotic resistant patterns among clinical isolates of E. coli and determination clonal relationship among E. coli in Kerman.Materials and Methods: A total of 127 clinical isolates of E. coli collected between October 2013 to October 2014, at four University Hospitals in Kerman city. Antibiotic susceptibility test was done by disc diffusion method. Phenotypic identification for ESBL production was confirmed by double disc synergy test. ESBL-positive isolates were screened for bla TEM, bla CTX-M, and bla SHV genes by PCR (polymerase chain reaction). UPGMA cluster analysis revealed high genetic diversity among E. coli isolates, which indicated lack of any significant genetic relatedness.Results: The ESBLs were found in (38. 5%) of isolates. Among 49 ESBL-producing E. coli isolates, 8.16% harbored all the three bla genes. The bla TEM was the predominant (93.8%) gene followed by bla CTX-M (87.7%) and bla SHV (6.1%). Resistances of ESBL isolates to other antibiotics were measured: ampicillin (77.5%), piperacillin (71.5%), co-trimoxazol (71.4%), while no resistance was observed for imipenem.Conclusion: Our study showed high ESBL incidence, with CTX-M as the emerging strain in our hospitals. By studying the profiles of MLVA it can be concluded that E. coli isolates have high heterogeneity.

Keywords:

Escherichia coli , broad-spectrum beta-lactamases (ESBL) , antibiotic resistance , clonal examination , MLVA