Outbreak of nosocomial bacteremias, caused by Enterobacter gergoviae and Enterobacter aerogenes, in the neonatal intensive care unit, case - control study

In this case-control study we describe epidemiological characteristics and evaluate risk factors for bacteremias caused by a rare human pathogen Enterobacter gergoviae, and Enterobacter aerogenes, among neonates in the intensive care unit, under conditions of nosocomial outbreak.Crude rate of bacteremias was 16 per 1000 admissions. Bacteremias most commonly occurred between 7th to 30th day of hospitalization and were 1.9 times more frequent in males than females. The following risk factors were significantly associated with the development of bacteremias: a) colonization or infection of neonates prior to the onset of bacteremia with Enterobacter spp. (OR=3.4, 95%CI=1.2-9.9) or non-Enterobacter spp. (OR=7.9, 95%CI=1,2-52.5); b) use of antimicrobial drugs most notably ceftazidime (OR = 7.8, 95% CI = 1.6.-38.6), or amikacin (OR = 7.5, 95% CI = 2.8-19.9); and c) invasive interventions: mechanical ventilation (OR = 4.7, 95% CI = 1.6-13.5), umbilical catheterization (OR = 3.1, 95% CI = 1.1-13.3), or nasogastric tube insertion (OR = 3.8, 95% CI = 1.8-8). These results show that some previously described risk factors for developing Enterobacter bacteremia were equally applicable in the case of Enterobacter gergoviae infections.In addition, the report represents an important contribution to establishing E. gergoviae as a relevant human pathogen with epidemiological potential, as it is the first case-control report in the region and one of a few in the world, analyzing outbreaks of bacteremias in the neonatal intensice care unit (ICU) caused by E. gergoviae.