Change in antibiotic susceptibility pattern of common oral antibiotics in Escherichia coli in urinary isolates: An eleven-year retrospective study

Introduction: Urinary Tract Infection (UTI) is the leading cause of bacterial infections. Billions of dollars are spent on a yearly basis to treat it empirically and fruitful results cannot be obtained unless we direct our efforts to a judicious choice of antibiotics and means to avoid the increasing bacterial resistance.1, 2, 3, 7 We observed the duration after which an organism showed significant change in antibiotic susceptibility (considering 20% as a significant change). This analysis aids us in knowing when we can expect an organism to acquire resistance to a particular antibiotic and hence increasing the effectiveness in the management of UTIs, with reduced risk of resistance.
Methodology: 10891 urinary isolates of Escherichia coli were collected from1st January 2002 to 31st December 2012. Samples were collected by convenient sampling and both inpatient and outpatient samples were included.
Results: The resistance pattern of four common oral antibiotics was collected in this study. Average Percentage resistance to Ampicillin, Amoxicillin-clav, Ciprofloxacin, and Trimethoprim-Sulfamethazole were found to be 84%, 41%, 58% and 66.7% respectively. Ampicillin and Amoxicillin-calv did not show much change in resistance over the 11 year period.
Conclusion: Significantly high resistance is noted to all commonly use oral antibiotics for urinary tract infection, and strict measures need to be taken to avoid this. Ampicillin and Amoxicillin-calv did not show significant change in resistance pattern throughout the 11 year period. Hence, they can be used for relatively longer period of time as an empirical therapy in low resistance areas without the need to check yearly for change in susceptibility pattern.