E. Coli Case Study

“STUDY OF VIRULENCE FACTORS AND ANTIBIOTIC SENSITIVITY PATTERN IN ESCHERICHIA COLI STRAINS ISOLATED FROM EXTRAINTESTINAL INFECTIONS”
INTRODUCTION

Escherichia coli (E. coli) is one of the most important members of the family Enterobacteriaceae and a commensal in the human intestinal tract. (1) As a commensal it contributes to the maintenance of health of a person. However, E.coli when enters into unnatural sites, can cause variety of conditions such as urinary tract infections, wound infections, bacteraemia, meningitis and other soft tissue infections. (2, 3)
Of the different organisms known to cause urinary tract infections (UTI), E. coli is the most predominant pathogen being isolated in 70 – 90% of cases. It has been accepted that UTI

Therefore, the treatment of E.coli infections is increasingly becoming difficult. It is necessary to know the antibiotic susceptibility pattern of pathogenic E.coli to select the correct antibiotic(s) for the proper treatment of the infections. (5)
E.coli is a Gram negative, motile, nonsporing, lactose fermenting bacillus. The ability of E.coli to cause extraintestinal infections depends largely on several virulence factors, which help in survival of E.coli under adverse conditions present in those

Those which aggregated with salt particles and formed clumps were considered hydrophobic. E.coli grown on MacConkey agar plates were inoculated into 1 ml of Phosphate buffer saline (PBS) at pH 6.8 and turbidity was matched with McFarland tubes 6 or 7 to get a colony count of 5x109 colonies/ ml. Different molar concentrations of ammonium sulphate namely 0.625M, 1.25M and 2.5M were prepared. One loopful (10µl) of bacterial suspension made in PBS was mixed with equal volume of ammonium sulphate solutions of different molarity on a clean glass slide and observed for one minute while rotating. The highest dilution of ammonium sulphate solution giving visible clumping of bacteria was noted as the salt aggregation test value. E.coli strains that had SAT value ≤ 1.25 M were considered