Resistance profiles and biofilm formation of coagulase negative staphylococci isolated from clinical specimens in a tertiary care hospital in Palestine
Background: Coagulase-negative staphylococci (CoNS) represent one of the major resistant nosocomial pathogens where its biofilm-related infections often fail to respond to antibiotic chemotherapy. Here, we studied the resistance profiles and biofilm formation in CoNS isolates from clinical specimens at Al Shifa hospital in Gaza, Palestine. Methods: This study was carried out from March to July 2016 and included 81 clinical isolates. Identification and antibiotic susceptibility testing were performed using VITEK-2 system. The presence of nuc and mecA genes was performed using multiplex PCR. Qualitative and quantitative biofilm assays were performed using standard methods. Results: Of the 81 clinical CoNS isolates, S. haemolyticus was the most common species (34, 42%), followed by S. epidermidis (26, 32.1%) and S. saprophyticus (13, 16%). The majority of isolates (83.9%) were from surgery, ICUs, pediatrics and medicine wards and the most common source was pus (28, 34.6%). Antibiotic resistance was highest against aminoglycosides, β-lactams, carbapenems, cephalosporins, fluoroquinolones, fosfomycin and macrolides. Though, no resistance was detected against rifampicin, vancomycin, teicoplanin, nitrofurantoin, linezolid and mupirocin. The antibiotic resistance among MR-CoNS was significantly higher than that among MS-CoNS. Nearly 88.9% of isolates were multidrug resistant with higher percentage among MR-CoNS. Most S. epidermidis (76.9%) isolates were biofilm producer, with statistically significant association between methicillin resistance and biofilm production. Conclusions: High rates of antibiotic resistance were found among CoNS to commonly used antibiotics and the majority were methicillin and multidrug resistance. Most S. epidermidis isolates were biofilm producer. These results justified the necessity for national programs and measures to monitor and manage the usage of antibiotics in the Palestinian hospitals and community.