Detection of enterotoxin genes seg , seh , sei , and sej and of a novel aroA genotype in Jordanian clinical isolates of Staphylococcus aureus Waseem El-Huneidi, Salwa Bdour, Adel Mahasneh 4 Department of Biological Sciences, Faculty of Science, University of Jordan, Amman, Jordan Received 27 July 2005; accepted 7 April 2006 Abstract The presence of staphylococcal enterotoxin (SE) genes (seg , seh , sei , and sej ) and the correlation of their prevalence with the genotypes were studied in 100 clinical isolates of Staphylococcus aureus . Polymerase chain reaction (PCR) of SE genes indicated that 39% of the isolates were enterotoxigenic. Thirty-seven percent of the total isolates were seg positive, whereas 24% and 4% were sei and seh positive, respectively. All isolates containing sei were positive for seg , whereas sej gene was not detected. Genotyping by PCR-restriction fragment length polymorphism analysis of the aroA gene revealed that 39% of the isolates were type A and 11% were type B, and 50% displayed a novel (N) genotype. The presence of the enterotoxin genes was independent ( P b 0.05) of the genotypes of the tested S. aureus isolates. This study has demonstrated that the seg was the most dominant enterotoxin gene and that the enterotoxigenic Jordanian S. aureus isolates belong to different genotypes, and N genotype was predominant. D 2006 Elsevier Inc. All rights reserved. Keywords: Enterotoxin seg; seh and sei genes; S. aureus ; Genotyping; aroA gene 1. Introduction Staphylococcus aureus is one of the most common causes of nosocomial and community-acquired infections (Archer, 1998). Such infections are often acute and pyrogenic and, if untreated, may spread to the surrounding tissues and meta- static sites (Lowy, 1998). S. aureus produces a wide variety of toxic proteins such as toxic shock syndrome toxin 1, exfoliative toxins, and enterotoxins (Becker et al., 2003; Jarraud et al., 1999). Staphylococcal enterotoxins (SE) are low-molecular weight proteins (molecular weight, 26 900–29 600 Da) that are usually divided into the classic (SEA to SEE) and newly described (SEG to SER and SEU) enterotoxins (Fueyo et al., 2005; Letertre et al., 2003; Llewelyn and Cohen, 2002). Various methods have been developed for the detection of the enterotoxins and related genes. Polymerase chain reaction (PCR) proved to be a useful tool for the rapid and reliable detection of such genes (Becker et al., 1998; Johnson et al., 1991; Tamaparu et al., 2001). The enterotoxin genes are not distributed uniformly among S. aureus strains (Becker et al., 2003; Nashev et al., 2004; Omoe et al., 2002). Genetic variation among these strains occurs in both enterotoxin and core genes (Becker et al., 2003; Jarraud et al., 2002; Moore and Lindsay, 2001). Therefore, the relationship between the distribution of these genes and the S. aureus genetic background has been studied by many investigators using different genotyping methods (Fueyo et al., 2001; Jarraud et al., 2002; Moore and Lindsay, 2001; Naffa et al., 2006). In many countries, S. aureus geno- typing has become part of an ongoing surveillance systems and an important tool in the study of strain origin, clonal relatedness, and epidemiology of outbreaks (Byun et al., 1997; Tambic et al., 1999). These genotyping methods include pulsed-field gel electrophoresis (Chiou et al., 2000; Schlichting et al., 1993), multilocus sequencing typing (Maiden et al., 1998; van Leeuwen et al., 2003), random amplification of polymorphic DNA (RAPD) (Fueyo et al., 2001; Saulnier et al., 1993), and PCR-restriction fragment length polymorphism (PCR-RFLP) analysis of the protein A gene (spa)(Shopsin et al., 1999), coagulase gene (Hookey et al., 1998), and aroA gene (Marcos et al., 1999). However, the PCR-RFLP analysis of the aroA gene (which encodes 5-enolpyruvylshikimate-3-phosphate synthase) allows a quick, easy, and reasonable discrimination among S. aureus strains (Marcos et al., 1999). 0732-8893/$ – see front matter D 2006 Elsevier Inc. All rights reserved. doi:10.1016/j.diagmicrobio.2006.04.002 4 Corresponding author. Tel.: +962-6-5355000; fax: +962-6-5348932. E-mail address: amahasneh@ju.edu.jo (A. Mahasneh). Diagnostic Microbiology and Infectious Disease 56 (2006) 127 – 132 www.elsevier.com/locate/diagmicrobio