Escherichia coli infection in Polish neonatology ICUs in 2009 to 2012

Introduction

The aim of our study was the analysis of the epidemiology of infections caused by ECO in Polish NICUs and their resistance to antibiotics, with particular reference to their impact on the safety of infants with very low birth weight, and their relationship to the care of women who are pregnant and in labour. The routes of transmission of ECO strains were also evaluated.

Methods

Continuous prospective infection surveillance was conducted in 2009 to 2012 in five NICUS and included 1,768 newborns whose birth weight was lower than 1,500 g.

Results

The incidence of ECO infections was 5.4% and 2.0/1,000 patient- days. The occurrence of ECO infections depended significantly on the NICU and ranged from 3.9 to 17.9%. Multivariate analysis that took into account the combined effect of demographic data (gender, gestational age and birth weight) and place of birth (NICUs, where the baby was born) showed that only the place of hospitalisation had a significant effect on the ECO infection risk. The highest levels of resistance among all ECO isolates were observed against ampicillin (88.8%) and amoxicillin/clavulanic acid (62.2%). ECO isolates showed very different pulsotypes and dominant epidemic clones were not detected. Cluster analysis based on PFGE of the 90 isolates showed 71 unique types, some of which were less than 70% similar, suggesting a genotypically variable population. Isolates that have identical pulsotypes usually were derived from the same patient (as in the case of 11 isolates) or were isolated from different patients of the same NICU in the same period of time (in the case of seven isolates). The location of the NICU and the site of the isolation did not appear to have a correlation in the cluster analysis

Conclusion

Unfortunately, the presented data indicate that antibiotic prophylaxis in the presence of symptoms such as chorioamnionitis and PROM did not help to reduce the risk of ECO infection in the group of examined infants. In addition, multivariate analysis demonstrated only one significant risk factor for ECO infection among infants with a birth weight <1,500 g; that is, the impact of the NICU. Epidemiology of ECO infections clearly indicated that observed cases of infections have no connection with the horizontal transmission (thus no proof of a link between the observed ECO infections with possible negligence in hand hygiene or excessive congestion on NICUs). This is confirmed by the fact that no epidemic clones were observed (DEC-2011/01/D/ N27/00104).