[Causative agents of intravenous catheter-related infections and their antibiotic susceptibilities]

Intravenous catheterization can lead to colonization as well as a broad spectrum of infections ranging from catheter site infections to catheter-related blood stream infections (CRBSIs). The aim of this study was to evaluate the distribution of causative agents and their antibiotic susceptibility patterns in CRBSIs and catheter site infections along with the colonization rates and colonizing microorganisms in Zonguldak Karaelmas University Hospital, Turkey. The results of cultures from catheter tips and/or intracatheter blood cultures and simultaneously taken peripheral blood cultures were sent to medical microbiology laboratory and were retrospectively investigated for 201 patients hospitalized between September 2007 and September 2009. The catheter tips were cultured by semi-quantitative and quantitative culture methods. Blood cultures from the catheters and peripheral veins were performed in BACTEC 9120 (Becton Dickinson, USA) blood culture systems. The antibiotic susceptibility tests were done by Kirby-Bauer disk diffusion method according to the guidelines of the Clinical and Laboratory Standards Institute (CLSI). Out of 201 patients included, 28 (13.9%) had CRBSIs and 13 (6.4%) had catheter site infections while colonization was defined for 55 (27.3%) patients. Of 28 patients with CRBSIs, Acinetobacter spp. were isolated from 11 including five carbapenem-resistant strains, methicillin-resistant coagulase-negative staphylococci (MRCNS) from eight, methicillin-susceptible coagulase-negative staphylococci (MSCNS) from two, Klebsiella pneumoniae from two patients and one of each patient's cultures yielded methicillin-resistant Staphylococcus aureus (MRSA), carbapenem-resistant Pseudomonas aeruginosa, Enterococcus spp., Escherichia coli and MRCNS + Enterococcus faecium. Of 13 patients with catheter site infections, five MSCNS, two methicillin-susceptible S.aureus (MSSA), two E.coli, and one of each K.pneumoniae, MRCNS, Enterococcus spp., K.pneumoniae + P.aeruginosa were isolated. No resistance to vancomycin and teicoplanin were detected among the staphylococci isolated from CRBSIs and catheter site infections. The distribution of the 55 colonizing microorganisms were as follows; 18 MSCNS, 18 MRCNS, four Acinetobacter spp., five K.pneumoniae, three E.coli, two MSSA, and one of each MRSA, P.mirabilis, P.aeruginosa, Corynebacterium spp., Candida albicans. In this study, the predominant microorganism isolated from CRBSIs was Acinetobacter spp., followed by coagulase-negative staphylococci. This unexpected distribution of the agents was related to the Acinetobacter spp. that have gained endemic potential following an Acinetobacter outbreak in our hospital in 2006. We emphasize that it is critical for any individual hospital to assess periodically the distribution and susceptibility profiles of isolates obtained from catheter-related infections to set out rational empirical treatment strategies.