Spectrum and Antimicrobial Susceptibility Pattern of Uropathogens: Indoor Versus Outdoor Isolates

Background and Objectives: The resistance of uropathogens to commonly prescribed antimicrobials is increasing globally. As the susceptibility of uropathogens varies according to place and time, the present study was undertaken to know the local epidemiology and antimicrobial susceptibility patterns (AMSP) of common bacterial uropathogens. This helps in formulating effective empirical treatment.

Methods: This is a prospective observational study, where a total of 3353 consecutive urine specimens over a period of one year in a tertiary care hospital were cultured by semiquantitative method. The pathogens isolated were identified by standard methods and their antimicrobial susceptibility was done by Kirby Bauer disk diffusion method as per Clinical Laboratory Standards Institute (CLSI) guidelines. The data was analyzed by using WHONET 5.6 software.

Results: Of the total 3353 samples, 63% were sterile, 24% showed significant growth, 5.27% showed insignificant growth and 7.45% were collection contaminants. The 812 samples with significant growth yielded 988 bacterial isolates with 814 (82%) gram negative bacilli (GNB) and 174 (18%) gram positive cocci (GPC). Gram negative uropathogens had low susceptibility to ampicillin, cotrimoxazole, norfloxacin and cephalosporins. They had good susceptibility to nitrofurantoin and aminoglycosides like amikacin, gentamicin followed by piperacillin-tazobactam and meropenem. ESBL production was observed amongst 40% of Escherichia coli and 60% of Klebiella pneumoniae isolates. Similarly gram positive uropathogens had low susceptibility to fluoroquinolones like norfloxacin, ciprofloxacin and tetracycline. They had good susceptibility to vancomycin, teicoplanin, linezolid and nitrofurantoin. Amongst the isolates from In Patient department (IPD) 36% of Staphylococcus aureus were MRSA and 2% of Enterococcus were Vancomycin Resistant Entercoccus (VRE).

Conclusion: Local epidemiology and susceptibility pattern of uropathogens should be studied to formulate effective empirical treatment regimen. Our study recommends use of Nitrofurantoin as best antimicrobial for UTI in uncomplicated, non-hospitalised patients. And use of aminoglycosides, or β lactam - βlactamase inhibitor combination agents like piperacillin/tazobactum and cefaperazone-sulbactam in complicated and serious hospitalized patients.