Central venous catheter-associated bloodstream infection and colonisation of insertion site and catheter tip. What are the rates and risk factors in haematology patients?

Skin colonisation is an important source for central venous catheter (CVC) colonisation and infection. This study intended to identify risk factors for skin colonisation prior to CVC placement (baseline colonisation) and within 10 days after CVC insertion (subsequent colonisation), for CVC-tip colonisation and for bloodstream infection (BSI). Within a randomised clinical trial, data of 219 patients with haematological malignancies and inserted CVC (with a total of 5,501 CVC-days and 4,275 days at risk) in two university hospitals were analysed. Quantitative skin cultures were obtained from the insertion site before CVC placement and at regular intervals afterwards. CVC-tip cultures were taken on CVC removal and data collection was performed. Statistical analysis included linear and logistic regression models. Age was an independent risk factor for colonisation prior to CVC placement (baseline colonisation). Independent risk factors for subsequent colonisation were baseline colonisation and male gender. High level of subsequent skin colonisation at the insertion site was a predictor of CVC-tip colonisation, and a predictor of BSI. High level of skin colonisation predicts catheter tip colonisation and possibly subsequent infection. Sustained reduction of bacterial growth at the CVC insertion site is therefore indispensable. Male patients are at particular risk for skin colonisation and may be a target population for additional insertion-site care before and during catheterisation.

IS26-Mediated Transfer of bla NDM-1 as the Main Route of Resistance Transmission During a Polyclonal, Multispecies Outbreak in a German Hospital.

One of the most demanding challenges in infection control is the worldwide dissemination of multidrug-resistant (MDR) bacteria in clinical settings. Especially the increasing prevalence of carbapenemase producing Gram-negative pathogens poses an urgent threat to public health, as these enzymes confer resistance to almost all ß-lactam antibiotics including carbapenems. In this study, we report a prolonged nosocomial outbreak of various NDM-1-producing Enterobacterales species due to clonal spread and cross-species exchange of plasmids and possibly transposons. Between July 2015 and September 2017, a total of 51 carbapenemase-positive isolates were collected from 38 patients and three environmental sources in a single German hospital. Combining molecular typing methods and whole genome sequencing, the metallo-ß-lactamase gene bla NDM-1 was found to be present in 35 isolates of which seven additionally carried the carbapenemase gene bla KPC-2. Core genome MLST (cgMLST) revealed different clusters of closely related isolates of Escherichia coli, Klebsiella pneumoniae, Citrobacter freundii, Morganella morganii or Enterobacter cloacae indicating clonal spread. The detailed reconstruction of the plasmid sequences revealed that in all outbreak-associated isolates blaNDM-1 was located on similar composite transposons, which were also very similar to Tn125 previously described for Acinetobacter baumannii. In contrast to Tn125, these structures were flanked by IS26 elements, which could facilitate horizontal gene transfer. Moreover, the identical plasmid was found to be shared by E. coli and M. morganii isolates. Our results highlight the importance of detailed genome-based analyses for complex nosocomial outbreaks, allowing the identification of causal genetic determinants and providing insights into potential mechanisms involved in the dissemination of antibiotic resistances between different bacterial species.