The role of a monthly active surveillance programme for multidrug-resistant Gram-negative bacteria in a neonatal intensive care unit: impact evaluation of preventive measures

Background: Antimicrobial resistance is a public health threat. Neonatal Intensive Care Unit (NICU) patients are particularly at risk, due to the large use of invasive devices and antimicrobial treatment. Since 2014 an active surveillance program of multidrug-resistant organisms is in place in the five NICUs of Palermo, Italy. High prevalence of multidrug-resistant Gram-negative bacteria (MDR-GNB) carriage observed in one NICU suggested the need of a long-lasting approach to achieve effective control of MDR-GNB circulation. Materials/methods: Rectal swabs were obtained every month from each hospitalized new-born. Samples were enriched in liquid cultures, plated in McConkey Agar with three antimicrobial discs (amoxicillin-clavulanate, meropenem, ceftazidime). Resistant colonies were isolated, identified and submitted for antimicrobial susceptibility testing and ESBL detection. Molecular characterization of MDR-GNB was performed using pulsed-field gel electrophoresis (PFGE). From November 2017 multiple intervention measures were done: - Strengthening of sample collection for two months; - Stakeholders meetings; - Standardized protocols for antimicrobial therapy and common procedures. Prevalence of MDR-GNB carriage between the pre-intervention (November 2016-October 2017) and the post-intervention period (November 2017-October 2018) was compared by chi-square test. Clinical features were analysed in a subgroup of patients to identify possible risk factors. All associated variables with p-values <0.25 were included in a multivariate logistic regression model. P<0.05 was considered significant. Results: 39 patients were included in the 2 months of strengthened microbiological surveillance. MDR-GNB and ESBL-Klebsiella pneumoniae (KP) were detected in rectal swabs (34.8%; 23.2%), nasal swabs (24.6%; 14.5%), oral swabs (14.5%; 5.4%), milk samples (32.1%; 17.9%) soother swabs (30.8%; 17.9%). ESBL-KP was also detected from a sub-intensive room surface. Thirteen ESBL-KP strains isolated from clinical and environmental samples showed identical or closely related PFGE patterns suggesting a common origin for all tested strains. Prevalence of MDR-GNB and ESBL-KP carriage after intervention significantly decreased compared to the year before (61.1% vs 20.6%; p<0.001 and 94.5% vs 53.8%; p<0.001). Admission in post-intervention period significantly reduced the risk of MDR-GNB carriage (OR=0.15, p=0.01). Conclusions: MDR-GNB broadly circulate in NICU setting, can colonize different body sites and spread by various vehicles. Cooperation between epidemiologist and clinicians can effectively reduce diffusion of antimicrobial-resistant bacteria.