Susceptibility pattern of Escherichia coli associated urinary tract infection: a comparison between spinal cord and nosocomial induced UTIs

Abstract number: 1733_622

Khorvash F., Mostafavizadeh K., Mobasherizadeh S., Javadi A., Behjati M.

Evolving resistant uropathogenes have been associated with the elevated risk of morbidity and mortality, both in nosocomial and spinal cord (SCI) associated urinary tract infections (UTI). Both of these complicated UTIs have concomitant risk factors for UTI confliction, as urinary catheterisation, probable poor hygiene, prolonged or intermittent antibiotic consumption and others. Regarding to this susceptibility, antibiotic resistance emerges, so more clinicoepidemiological studies are needed to facilitate empirical therapy and decrease time and costs toward diagnosis and treatment.

Method and Material: During 18 months period of this study (2005 and early 2006) 100 and 80 E. coli specimens from cases of diagnosed nosocomial UTI and spinal cord injury associated (SCI) UTI have been isolated by standard microbiological methods respectively. MIC of 10 antibiotics on isolated bacteria was determined by gradient concentration method (E-Test^®; AB BIODISK Co. Sweden). Quality control was tested by E. coli ATCC 25922. Data was analysed by SPSS 13 and Whonet 5 software.

Results: Antibiotic resistant uropathogenes were more prevalent among nosocomial UTIs rather than SCI associated UTI (P < 0.05). According to break point used for susceptibility meet CLSI M7-A6 (Clinical and Laboratory Standard Institute) criteria, resistance of isolated E. coli in nosocomial and SCI associated UTIs was 13.9% and 5.9% in amikacin (P < 0.01), 65% and 40.5% in ceftazidim (P < 0.05), 69.8% and 32.4% in ceftriaxone (P < 0.005), 50% and 41.2% in ciprofloxacin (P < 0.05), 56.9% and 13.6% in gentamicin (P < 0.005), 2.1% and 0% in imipenem (P < 0.005), 3.9% and 0% in meropenem (P < 0.005), 73.6% and 63.6% in trimethoprim/Sulfamethoxazole (P < 0.05) respectively. Only resistance to nalidixic acid was mildly higher in SCI E. coli (79.1%, 73.6%). MIC₅₀ of all antibiotics were higher in nosocomial E. coli (p < 0.05).

Conclusion: Despite more risk factors for antibiotic resistant E. coli in SCI population, the emerged antibiotic resistant E. coli was more diagnosed in nosocomial UTIs. Although this difference can be attributed to the hospital environment, more studies are needed to uncover the causes of these findings.