Nosocomial transmission of carbapenem-resistant Klebsiella pneumoniae in an Italian university hospital: a molecular epidemiological study

Aim: To describe the phenotypic and genotypic profiles of Klebsiella pneumoniae carbapenemase-producing K. pneumoniae (KPC-Kp) strains isolated from patients with invasive infections at an Italian university hospital in order to assess the epidemiological trend. Methods: An observational prospective study was undertaken at the University Hospital of Sassari, Italy to detect KPC-Kp strains in patients with invasive bacteraemia. Isolates were identified phenotypically; carbapenemase production was assessed using phenotypic and genotypic methods. Sequencing of blaKPC genes, pulsed-field gel electrophoresis and multi-locus sequence typing were performed. Results: During the period 2015–2017, 46 cases of invasive infection with K. pneumoniae were recorded. Two-thirds (67.4%) of the patients were male, and the mean age was 69.4 years. Most patients had at least one comorbidity (56.5%) and/or had been hospitalized previously (70.5%), 81.8% had current or recent medical device use, and 85.4% had recent antibiotic exposure. The mortality rate was 52.3%. A multi-drug-resistant pattern (including carbapenems, fluoroquinolones, third-/fourth-generation cephalosporins) was shown for all K. pneumoniae isolates. KPC-3 and -2 were produced by all strains. The most common sequence types were 512 (91.3%) and 101 (8.7%), grouped into three clusters (A, A1 and B). Conclusions: A high incidence of KPC-Kp in patients with invasive infections was recorded at an Italian university hospital compared with the incidence measured before 2015. This study confirmed the importance of the KPC-3 carbapenemase variant, as reported by other Italian studies. High mortality and comorbidity rates appear to be associated with KPC-Kp infection.