Surveillance of methicillin-resistant Staphylococcus aureus, multidrug-resistant Gram-negatives and fungi colonization in the Neonatal Intensive Care Units in the city of Palermo.

Abstract

Introduction Multidrug-resistant organisms are a serious public health problem, particularly in critical hospital wards such as the Neonatal Intensive Care Units (NICUs). Hospitalized neonates are at high risk for healthcare-associated infections leading to higher morbidity and mortality rates, because of their poor immune defences, frequent exposure to antibiotics, invasive procedures and contacts with healthcare-workers. Our study aimed to evaluate the prevalence of colonization by methicillin-resistant Staphylococcus aureus (MRSA), multidrug-resistant Gram-negatives (MDRGNs) and fungi in the five NICUs of the city of Palermo. Methods From February 2014 to January 2015, an active surveillance culture (ACS) program was set up in the five NICUs of Palermo (ARNAS Civico-NICU1, Ingrassia Hospital-NICU2, Villa Sofia-Cervello Hospital-NICU3, Buccheri La Ferla Hospital-NICU4 and AOUP "Paolo Giaccone"-NICU5). From each patient nasal and rectal swabs were monthly collected to look for MRSA, MDRGNs and fungi. Swabs were pre-incubated at 37°C overnight in BHI enrichment broth, and cultured on selective media. Suspected S. aureus colonies were confirmed by cefoxitin susceptibility testing. MDRGNs were selected by antibiotic disk screening and tested to detect extended-spectrum beta-lactamase” (ESBL) and carbapenemase-producing isolates. For fungal detection swabs were directly inoculated on chloramphenicol-Sabouraud dextrose agar plates and incubated at 30°C for 72 hrs. Yeast-like colonies were identified by subculturing on CHROMagar Candida and eventually confirmed by the API20CAUX test. Prevalence rates of colonization of the different NICUs were compared by the chi-square test. Results The average daily number of hospitalized patients was 16 in NICU1, 9 in NICU2, 21 in NICU3, 15 in NICU4, 11 in NICU5. Prevalence of MRSA colonization ranged between 3.6% in NICU3 and 28.8% in NICU4, showing statistically significant differences between the NICUs. Prevalence of colonization by MDRGNs ranged between 53.9% for NICU1 and 14% for NICU4 with statistically significant differences between the NICUs. The most frequently isolated MDRGN organisms were Klebsiella pneumoniae, Escherichia coli and Enterobacter spp., with a prevalence between 1.9% and 57.2% for ESBL-producing and between 0% and 3.5% for carbapenemase-producing isolates. Fungal colonization was never detected in NICU2, whilst the highest prevalence values were 7.2% for C. albicans in NICU4 and 5.9% for non-albicans Candida spp. in NICU5. Statistically significant differences were found. Discussion Spread of multidrug-resistant organisms proved to affect all the NICUs under investigation, with a higher prevalence of MRSA in NICUs 4 and 2 and a higher prevalence of MDRGNs in NICUs 1 and 5. Fungal colonization prevalence was different between the NICUs with NICU4 being more affected by C.albicans and NICU5 by non-albicans Candida spp. These differences could be attributable to different structural and organizational characteristics and the recurrent epidemic spread of some organisms by cross-transmission. The widespread dissemination of MRSA and ESBL producing isolates and the emergence of carbapenem-resistant Enterobacteriaceae require a continuous effort in implementing preventive measures, control interventions and staff training.