INTERNATIONAL JOURNAL OF AGRICULTURE & BIOLOGY 1560–8530/2007/09–6–800–806 http://www.fspublishers.org Detection of Methicillin/Oxacillin Resistant Staphylococcus aureus Isolated from Some Clinical Hospitals in Cairo Using Meca/Nuc Genes and Antibiotic Susceptibility Profile ABEER A. RUSHDY 1 , MOHAMED S. SALAMA† AND AMAL S. OTHMAN Botany Department, Faculty of Girls for Art, Science and Education and †Science, Ain Shams University, Cairo, Egypt 1 Corresponding author’s e-mail: elsaadawy@link.net ABSTRACT This study reports the detection of methicillin/oxacillin-resistant Staphylococcus aureus (MRSA/ORSA) strains and generation of antibiogram profile of S. aureus clinical isolates from three Egyptian hospitals. PCR amplification, spot inoculation and oxacillin disc diffusion tests were applied to compare their MRSA/ORSA detection abilities. From 200 bacterial isolates tested, 83 (41.5%) were confirmed as S. aureus of which 51 (61.45%) were oxacillin resistant (ORSA). Out of 51 isolates 26 had single resistance (oxacillin resistance), while 25 had double resistance (oxacillin & methicillin) resistance (MRSA/ORSA). Antibiotic susceptibility, of all isolates, to seven different antibiotic groups was tested. Quinolones and aminoglycosides were the most effective groups, 45.1% of the isolates were susceptible to vancomycin. However, 27.5% of the isolates were multidrug resistant, against many of the available antibiotics and thus there is an urgent need for alternative antibiotics. Using the PCR assay, 26 ORSA isolates were found to have nuc gene and 25 MRSA/ORSA had mec A and nuc genes. Their amplification on agarose gel revealed the presence of nuc gene at 276 bp and for mec A gene at 533 bp. The sequencing of both genes was done and sequence allignment of both genes showed 99% and 97% homology between mec A and nuc genes, respectively. Key Words: S. aureus; MRSA/ORSA; Methicillin resistant; mec A/nuc genes; Antibiotic-susceptibility INTRODUCTION Staphylococcus aureus is the causal agent of most of the staphylococcal diseases and is currently a versatile microbial pathogen that has evolved resistance to all antibiotic classes (Jomaa et al., 2006; Cockfield, 2007). It is associated with serious community-acquired and nosocomial infections (Day et al., 2001; Berger-Bachi, 2002). Its high level of adaptation to hospital environments has been deeply facilitated by the acquisition of methicillin resistance, an evolutionary step that converted S. aureus to one of the most common nosocomial pathogen nowadays (Oluwatuyi et al., 2004; Saxena & Panhotara, 2005). The global spread of methicillin-resistant S. aureus (MRSA) constitutes one of the most serious contemporary challenges to the treatment of hospital-acquired infections (Szczepanik et al., 2007). MRSA carries a uniquely effective antibiotic resistance mechanism that can protect the microorganisms against all members of ß-lactam antibiotics. Compounding the problem is the striking ability of MRSA to acquire resistance to other groups of antimicrobial agents, which makes infections caused by these pathogens very difficult to manage and costly to treat (Crisόstomo et al., 2001; Hiramatsu et al., 2002; Aires De Sousa & De Lencastre, 2004). Currently, vancomycin is accepted worldwide as the last armament against MRSA infections (Hiramatsu 2001; Robinson & Enright, 2004). Un-fortunately, clinical isolates of vancomycin-resistant S. aureus have been reported recently (Centers for Disease Control & Prevention, 2004). The emergence of S. aureus isolates resistant to vancomycin and other wide range of structurally un-related antibiotics have elevated MRSA into a multidrug-resistant 'Superbug", making it more dangerous than ever in a hospital environment and also recently, in the healthy community (Norazah et al., 2003; Lu et al., 2005). The objective of the present study was to detect and identify the multidrug and non-multidrug methicillin/ oxacillin resistant S. aureus (MRSA & ORSA) from three hospitals in Egypt using antibiotic disc diffusion method. The study also aimed at the identification of specific genes responsible for resistance to oxacillin and to methicillin using the PCR technique. MATERIALS AND METHODS Clinical specimens. Two hundred swab samples were collected in 2003 on mannitol salt broth medium from different hospital departments; 126 swab samples from Intensive Care Units of Neurosurgery, Chest and Cardiac Surgery and Cardiovascular department of Al-Hussein University Hospital, 54 samples from Orthopedic department of Sayed Galall-University Hospital and 20 from the medical laboratory of Dar El-Shefa Hospital. Samples were taken from, patients, nurses and workers and indoor environment of the three hospitals.