Antibiogram and Plasmid profiling of clinical multidrug resistant Escherichis coli

Abstract

Introduction: Multiple antibiotic resistances among common bacterial pathogens have been established as an alarming public health problem elsewhere. This study was aimed to explore prevalence of Extended-spectrum beta-lactamase (ESBL) producers among multi drug resistant (MDR) and plasmid profiling patterns of Escherichia coli isolated in Kathmandu Model hospital, Nepal over three months period.

Methods: Altogether 49 isolates were randomly selected among the reported MDR E. coli and retested for the susceptibility pattern and ESBL production by Kirby- Bauer disc diffusion test. Minimum Inhibitory Concentration of the isolates towards (fluro) quinolones was determined by agar dilution method. Plasmids from isolates were extracted by alkaline lysis method.

Results: All isolates were completely resistant to Amoxycillin but sensitive to Imipenem. A very high prevalence (44, 89.8%) of ESBL was detected. Most of the isolates were resistant to commonly uses antibiotics such as Quinolones, Tetracyclines and Cotrimoxazole. Among Quinolones, the Minimum Inhibitory Concentration (MIC) range for Nalidixic acid, Ciprofloxacin and Ofloxacin were 512->4093, 8-4096 and 1-256 µg/ml respectively. All 31 (63.3%) plasmid- harboring isolates contained a>33.5 kb sized plasmid. Among them, seven isolates possessed multiple (2 – 7) plasmids. Overall, twelve different resistance patterns were observed among the bacteria. Based on the patterns, the high molecular weight plasmid seemed to contain most of the resistance genes.

Conclusion: It is suspected that multi drug resistance and ESBL production in E. coli with resistance to Quinolones may be due to their high molecular weight plasmids. So, continuous antibiotic susceptibility test and surveillance of the plasmid and chromosome of E. coli is essential as plasmid analysis has been applied to determine the evolution and spread of antibiotic resistance among isolates.