Trends in Klebsiella pneumoniae strains isolated from the bloodstream in a teaching hospital in southern Italy.

Klebsiella pneumoniae is a common nosocomial pathogen involved in many infectious diseases such as bacteraemia, urinary and respiratory tract infections. It is responsible for the rise in morbidity and mortality rates since most clinical isolates exhibit resistance to several antibiotics. Moreover, the epidemiology of these nosocomial infections is variable across countries and regions. From January 2015 to December 2017 we retrospectively analysed the bloodstream infections caused by K. pneumoniae strains in hospitalised patients with the aim of studying the temporal trends of wild type (WT), multi-drug resistant (MDR), extended drug resistant (XDR), pan-drug resistant (PDR) and carbapenem-resistant (CR) strains. In all, 439 K. pneumoniae isolates from 356 patients were collected from all units of the Policlinico of Bari. The majority of clinical isolates were collected from the intensive care unit (125, 28.47%), haematology (34, 7.74%), rehabilitation (27, 6.15%) and cardiac surgery wards (25, 5.69%). Moreover, the majority of the isolates were classified as CR (325, 74.03%, 95%CI: 69.61-78.19) and XDR (255, 58.09%, 95%CI: 53.31-62.72). Annual prevalence rates and monthly counts were analysed using the Chi Squared test for trends and the Poisson regression with multiple p-value correction according to Benjamini and Hochberg's procedure. The annual relative frequencies of the XDR and CR K. pneumoniae isolates decreased significantly from 63.37% to 48.44% and from 78.48% to 63.28% respectively, while WT K. pneumoniae significantly increased from 13.95% to 23.44%. Poisson regression analysis confirmed the presence of a decreasing monthly trend for the XDR and CR K. pneumoniae count series. In order to control the spread of antibiotic resistance, more inclusive surveillance data will be needed to either confirm these results or improve antibiotic stewardship measures.