Non-Susceptibility Trends Among Methicillin-Resistant Coagulase-Negative Staphylococci Isolated From Blood Cultures

Coagulase-negative staphylococci are a significant cause of hospital-acquired bacteremias. There is an increase of infections induced by methicillin-resistant strains, with growing resistance to other antibiotics. The aim of the study was to analyze the resistance of methicillin-resistant coagulase-negative staphylococci isolated from hemocultures in a five-year period. The study was carried out in the microbiology laboratory of the Institute for Pulmonary Diseases of Vojvodina, from 2008 to 2013. Coagulase-negative staphylococci were isolated from 196 hemocultures. Susceptibility tests were performed using the disc diffusion method. Of 196 coagulase-negative staphylococci, 122 (62.2%) were resistant to methicillin, of which 112 (91.8%), 105 (86.1%), 103 (84.4%), 88 (72.1%) were resistant to erythromycin, gentamicin, ciprofloxacin and clindamycin, respectively. All strains were susceptible to vancomycin and linezolid. Multiple resistance was registered in 100 (82%) strains. The most common resistance pattern was gentamicin-erythromycin-clindamycin-ciprofloxacin. Multiple resistance was established in a significant percentage of methicillin-resistant strains.