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 biofilmrelated 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 2013 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 MRCoNS. Most S. epidermidis (76.9%) isolates were biofilm producer, with statistically significant association between methicillin resistance and biofilm production. Resistance profiles and biofilm formation of coagulase negative staphylococci isolated from clinical specimens in a tertiary care hospital in Palestine Nahed A. Al Laham1, Emad Abou Elkhair2, Abdallah Bashir2, Nahed Abdelateef3 1 Department of Laboratory Medicine, Faculty of Applied Medical Sciences, Al Azhar University-Gaza, Gaza Strip, Palestine. 2 Department of Biology, Faculty of Science, Al Azhar University-Gaza, Gaza Strip, Palestine. 3 The Central Laboratories, Ministry of Health, Gaza Strip, Palestine. Contact information: Dr. Nahed A. Al Laham. Address: Department of Laboratory Medicine, Faculty of Applied Medical Sciences, Al Azhar University-Gaza, P. O. Box 1277, Gaza Strip, Palestine.  nahedallaham@gmail.com The InTernaTIonal arabIc Journal of anTImIcrobIal agenTs ISSN: 2174-9094 2017 Vol. 7 No. 3:4 doi: 10.3823/814 This article is available at: www.iajaa.org / www.medbrary.com 2 Introduction Coagulase-negative staphylococci (CoNS) are now representing one of the major nosocomial pathogens and among the most frequently isolated bacteria in the clinical microbiology laboratories [1-5]. They are responsible for bacteremia, endocarditis, mediastinitis, meningitis and progressive joint destruction mainly in patients with neutropenia, indwelling foreign devices, intravascular catheters or other foreign bodies [1, 3, 4]. The clinical most relevant CoNS are Staphylococcus epidermidis, S. lugdunensis, S. saprophyticus , and S. capitis [6, 7]. Biofilm production by CoNS, specially S. epidermidis , is considered as an important factor in the pathogenesis of implanted medical devices associated infections [1, 2, 8, 9]. Biofilm formation takes place in four successive phases: the attachment of the bacteria to biotic or abiotic surface; the proliferation and accumulation of bacteria in multilayered cell clusters; the growth of biofilm into a thick and structured layer, and finally the detachment and circulation of single cells or cell agglomerates via the bloodstream [1, 2]. Many literature surveys revealed that CoNS showed high resistance against most of the commonly used therapeutic antibacterial agents including methicillin. Irrespective of geographical locations, a worldwide SENTRY study showed that, about 70-75% of CoNS are resistant to methicillin [10]. There is a significant increase in the methicillin-resistant coagulase negative staphylococci (MR-CoNS) infections and these bacteria have recently started to gain resistance to other widely used antibiotics [11-14]. The increased recognition of pathogenic potential of CoNS and emergence of drug resistance among them justify the need to identify various species of CoNS and determine their antibiotic resistance pattern. Epidemiological data about CoNS in Palestine are either scarce or insufficient [15]. To the best of our knowledge, this is the first report describing clinical CoNS infection within the Gaza Strip hospitals. To that end, we conducted this study to determine the frequency of CoNS species isolated from various clinical specimens and to assess their resistance profile to most commonly used antibiotics at Al Shifa hospital in Gaza Strip. Moreover, biofilm forming capacity of S. epidermidis isolates was investigated. Materials and Methods Study design and setting This study was conducted for five months between March and July 2013 at the clinical microbiology laboratory of the largest medical complex hospital