ABSTRACT
Extended spectrum beta- Lactamase producing klebsiella [ESbetaL-KP] is an important cause of nosocomial infections in neonatal intensive care units [NICUs]. We conducted a prospective cohort study in the NICU, Mansoura University Children's Hospital, over a period of twelve months starting from June 2005 to May 2006, to assess the incidence of ESbetaL-KP, identify the frequency of SHV-1 and SHV-2 gene acquisition among ESbetaL-KP isolates, and the risk factors associated with ESbetaL-KP infection. Antimicrobial susceptibility was determined by, phenotypic confirmation of ESbetaL production was done by the double-disk synergy test [DDST] and Etest. Genetic detection of SHV-1 and SHV-2 genes in ESbetaL-KP isolates was done by polymerase chain reaction [PCR] and restriction fragment length polymorphisms [RFLP]. Risk factors associated with ESbetaL-KP infection were analyzed by both univariate and multiple logistic regression methods. Three hundred and ninety-eight neonates were enrolled in the study cohort. The overall nosocomial infection incidence rate was 36.6%. Klebsiella species was the commonest organism [27 among 138 bacterial isolates [19.6%]]. Eighteen klebsiella isolates [66.7%] exhibited phenotypic ESbetaL- resistance patterns. PCR amplicons from the 18 ESbetaL-KP isolates were subjected to RFLP analysis which revealed the presence of SHV-2 in all 18 isolates [100%], SHV-1 gene in 8 strains [44.4%]. Independent risk factors for ESbetaL-KP infection were: mechanical ventilation [odds ratio [OR]: 4.18, 95% confidence intervals [CI]: 1.57 -11.00]; birth weight < 1500 g [OR: 3.19, CI: 1.22 - 8.30]; duration of hospitalization > 15 days [OR: 4.09, CI: 1.17-14.40]; total parenteral nutrition [TPN] [OR: 4.93, CI: 1.12 - 21.70]; and prior use of oxyimino-antibiotics [OR: 4.87, CI: 1.10 -21.50]. Neonates infected with ESbetaL-KP higher mortality [27.8%] compared to other neonates [11%] [P=0.04]
Conclusion: This study confirms the high incidence of ESbetaL-KP in our NICU and further demonstrates the role of genes coding for SHV-1 and SHV-2 enzymes in clinical and environmental isolates. Independent risk factors for acquisition of ESbetaL-KP were mechanical ventilation; birth weight 15 days; and prior exposure to oxyimino antibiotics. Neonates infected with ESbetaL-KP experienced increased mortality compared to other neonates