Background & objectives: Extensive use of antibiotics has added to the escalation of antibiotic resistance. This study was undertaken to evaluate the association, if any between antibiotic use and resistance in a hospital setting, and also detect the predominant mechanism of antibiotic resistance in Escherichia coli and Klebsiella pneumoniae over a period of 10 years.
Methods: In a retrospective study of 10 years, a total of 77,618 blood culture samples from 2000 to 2009 from indoor patients were screened and those yielding E. coli and K. pneumoniae were included in the study. Antibiotic susceptibility records as well as the percentage of ESBL producers were noted. A total of 423 isolates of 2009 were also screened for AmpC and carbapenemase production. Antibiotic consumption data of 10 years were analysed.
Results: ESBL producing E. coli increased from 40 per cent in 2002 to 61 per cent in 2009, similarly there was a significant (P<0.05) rise in resistance to cefotaxime (75 to 97%), piperacillin-tazobactum (55- 84%) and carbapenem (2.4-52%) in K. pneumoniae. A significant (P<0.05) association was observed between resistance and consumption of carbapenem and piperacillin and tazobactum consumption in K. pneumonia.
Interpretation & conclusions: Our study demonstrated a rise in consumption and resistance to broad spectrum antimicrobial agents and also established an association between consumption and resistance to these antibiotics. Over a period of 10 years, the emergence of pan-resistance in K. pneumoniae could be due to the production of carbapenemases whereas ESBL production was the common mechanism of resistance in E. coli. This study warrants a directed effort towards continued surveillance and antibiotic stewardship to minimize selection pressure and spread.