Frequency of Isolation of Enterobacter Species from a Variety of Clinical Specimens in a Teaching Hospital in Nigeria

Purpose: To determine the frequency of occurrence of Enterobacter species and their antibiogram from clinical specimens of blood, cerebrospinal fluid, urine and wound obtained from University of Benin Teaching Hospital, Benin City, Nigeria.Methods: Specimens were obtained from patients who were seen at the various units of the hospital during the period January 2008 to June 2010. The total number of specimens was 6632, and were obtained from 1678 adult males, 2010 adult females and 2944 children. The specimens were collected prior to commencement of antibiotic therapy, and cultured immediately using standard bacteriological methods. Growths were identified by colonial morphology and characteristics, and biochemical reactions. Antimicrobial sensitivity test was performed according to Kirby-Bauer disc diffusion method as per Clinical and Laboratory Standards Institute (CLSI) recommendation. The control organism was a sensitive strain of Eschrichia coli (NCTC 10418).Results: Two species of Enterobacter, namely, E. aerogenes (104; 97.2 %) and E. sakazakii (3; 2.8 %) were isolated from the four types of clinical specimens, accounting for 1.6 % of all the samples. Sensitivity to antibacterials was as follows: ceftazidime (55.0 %), ofloxacin (53.3 %) and amoxicillin clavulanate (48.3 %). They were strongly resistant to the other antibiotics used in the study, especially the cephalosporins. There was no significant difference in infection rate among the age groups (p > 0.05). However, there was significant difference (p < 0.05) between isolates from cerebrospinal fluid, on the one hand, and those from wound, urine and blood, on the other hand. Conclusion: The rate of isolation of Enterobacter species in the health facility was low. Remarkable drug resistance of the organisms make them clinically significant pathogens.Keywords: β-Lactam antibiotics, Opportunistic infections, Bacterial resistance, Enterobacter species