OXA-48-producing Klebsiella pneumoniae in a neonatal intensive care unit in Palermo, Italy

Abstract

Objectives Surveillance cultures are of great importance to detect the emergence of multidrug resistant (MDR) bacteria in high-risk settings and prevent the occurrence of colonization and clinical infection cases. We report the isolation of OXA-48-harbouring Klebsiella pneumoniae sequence type (ST) 530 in a Neonatal Intensive Care Unit (NICU) in Palermo, Italy. Methods Since June 2009, a routine surveillance protocol is in place in the NICU of the University Hospital of Palermo, including nasal and rectal swabs obtained on a weekly basis to monitor the prevalence of colonization by methicillin- resistant Staphylococcus aureus, MDR Gram-negatives and glycopeptide-resistant enterococci. Enteric colonization by antibiotic-resistant Gram negatives is assessed by culturing overnight broth-enriched rectal swabs onto MacConkey agar plates with disks of meropenem (10 mg) and ceftazidime (30 mg). Colonies growing within antibiotic inhibition zones are subcultured, biochemically identified and submitted to antimicrobial susceptibility testing by disk diffusion method and E-test and to ESBL detection according with the European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines. Beta-lactamase genes are identified by polymerase chain reaction (PCR) amplification and sequencing. Multilocus sequence typing (MLST) is performed and STs are determined using the K. pneumoniae MLST database (http://www.pasteur.fr/recherche/genopole/PF8/mlst/Kpneumoniae.html). Results In September 2013 an isolate of OXA-48 carbapenemase producing K. pneumoniae was identified from a newborn admitted from another hospital. Antimicrobial susceptibility testing showed susceptibility to 3rd and 4th generation cephalosporins and to aminoglycosides, intermediate suceptibility to imipenem and meropenem and resistance to ertapenem. PCR amplification tested positive for blaOXA-48 gene, and negative for other beta-lactamase genes. The isolate was identified as K. pneumoniae ST530 by MLST. The patient stayed in the NICU for five weeks, and OXA-48 K. pneumoniae colonization was confirmed at every weekly screening. During the last two weeks a second newborn tested positive for K. pneumoniae with a similar antimicrobial resistance pattern, which was confirmed to belong to ST530. Infection control prevention measures were strenghtened. The two colonized patients were discharged in mid-October and no further cases were detected. Conclusions Carbapenem-resistant Enterobacteriaceae are an emerging threat in Europe, particularly in the Mediterranean basin. The frequent horizontal transmission of plasmid-related resistance genes among different strains and species is allowing the epidemic diffusion of such MDR organisms in Europe in the last years. The remarkable potential for causing invasive infections and the limited therapeutic options associated with high mortality rates are of great concern. The implementation of surveillance programmes and infection control measures particularly in high-risk settings should be considered an essential strategy for public health interventions.