Molecular typing of β -lactamase -producing Escherichia coli: Multiple Locus variable number tandem repeat analysis Versus Pulsed-field gel electrophoresis

β -lactamase -producing E. coli is the most important agent causing   urinary tract infections both in community and hospitals. Strain typing including MLVA and PFGE are the most common epidemiologically   tools not only for detecting the cross transmission of nosocomial pathogens but also for determining the source of infection.

The present study was carried of for comparison of discriminatory power of MLVA and PFGE methods. A Total of 230 isolates of E. coli from patients with urinary tract infections were examined for identifying and antimicrobial susceptibility testing MLVA and PFGE methods were used for molecular typing of all isolates.

Out of 230 isolates, 130 ( 56.5%) β -lactamase -producing E. coli isolates were found in this study. The diversity indices of the VNTR loci showed an average diversity of 0.48 and 0.54 for 7-loci and 10-loci respectively. The discriminatory power of PFGE showed a value of 0.87.

Our study showed that PFGE is more discriminatory than MVLA. MLVA is a     PCR- based method and generates unmistakable data, in contrast to PFGE. Optimization of      polymorphic VNTR is essential to improve the discriminatory power of MLVA basis on  geographical region.