Isolation and identification of E. cowanii from powdered infant formula in NICU and determination of antimicrobial susceptibility of isolates

ABSTRACT

Enterobacter cowanii is a genus of common gram-negative, facultatively anaerobic, rod-shaped, non-spore-forming bacterium of the Enterobacteriaceae family. This organism can be potentially a powdered infant milk formula-borne opportunistic pathogen. The aim of this study was to isolate and identify E. cowanii from consumed powdered infant formula milk [PIF] in intensive care units [NICU] and to determine antimicrobial susceptibility patterns of this bacterium. E. cowanii was isolated according to FDA method in 125 samples of PIF milk purchased from drug stores between Jun 2011 and March 2012. For final confirmation, biochemical tests embedded in API-20E system were used. The drug susceptibility test was performed using the disc diffusion method according to CLSI recommendations. Out of the 125 PIF samples investigated, 4 [3.2%] samples were positive for E. cowanii. All four isolates from PIF samples were uniformly susceptible to imipenem, meropenem, ceftazidime, ciprofloxacin, and colistin. Fifty percent of isolates were resistant to ampicillin, amoxicillin, and cotrimoxazole. Analysis of the results indicated that complementary studies are necessary to clarify the possible role of E. cowanii as a food contaminant, in common NICU infections and high risk groups including persons with underlying disease and immunocompromised individuals