Occurrence of Enterobacter aerogenes in Clinical Specimens and its Antimicrobial Resistance

Abstract

This study was carried out in Khartoum state during the period from November 2008 to March 2009, to determine the occurrence and antimicrobial resistance of Enterobacter aerogenes isolated from patients suffering from urinary tract infections and wound infections. Three hundred and thirty nine urine specimens and seventeen wound exudates specimens were collected from patients attending Military Hospital, Omdurman Teaching Hospital and Khartoum Teaching Hospital. Both specimens were cultured on blood and MacConkey's agars. Identification of the isolates was done by colonial morphology, Gram stain and biochemical tests using API E 20. Modified Karby-Bayer diffusion method was adopted to determine the resistance rate of E. aerogenes isolated from urine, to nitrofurantoin, co-trimoxazole, nalidixic acid, amoxyclave and amoxicillin also to determine the resistance rate of E. aerogenes isolated from infected wound, to amikacin, ciprofloxacin, ceftriaxone, ticarcillin and amoxicillin. Minimum inhibitory concentration (MIC) was done to co- trimoxazole, amoxicillin, amikacin, ciprofloxacin and ticarcillin antibiotics by E -test. Of the three hundred and thirty nine urine specimens and seventeen wound exudates specimens examined, 11 (3.1%) E. aerogenes were recovered. 7 (0.6%) of the isolates were recovered from urine specimens and rest 4 (0.3%) were recovered from wound exudates specimens. The results revealed that the antimicrobial resistance of E. aerogenes follows; Co-trimoxazole, ceftriaxone, ticarcillin was as and amoxycillin (100% each), nalidixic acid and amoxyclave (85.7% each), nitrofurantoin (42.8%), amikacin and ciprofloxacin(0%). The result indicated that the MIC, MIC 50, MIC90 of ciprofloxacin were (0.05 to 0.06 μg/ml, 0.05μg/ml and 0.06μg/ml), co-trimoxazole, amoxycillin, and ticarcillin (>240μg each) and amikacin (0.5-1μg/ml, 0.5μg/ml and >30μg/ml). The study concluded that the existence of E. aerogenes in clinical specimens was slightly high compare to other bacteria. The antimicrobial resistance of E. aerogenes to most traditionally used antibiotics was very high.