Enterotoxicity and genetic variation among clinical Staphylococcus aureus isolates in Jordan

Abstract

A total of 100 Jordanian clinical Staphylococcus aureus isolates was analysed for the presence of the enterotoxin genes sea, seb, sec, sed and see using multiplex PCR. Twenty-three isolates (23 %) were potentially enterotoxigenic. The prevalence of sea, sec and sea plus sec among the total clinical isolates was 15, 4 and 4 %, respectively. None of the isolates harboured sed, seb or see genes. S. aureus isolates were subjected to DNA fingerprinting by randomly amplified polymorphic DNA (RAPD) analysis to test whether isolates harbouring the toxin genes were genetically clustered. A total of 13 genotypes was identified at a 47 % similarity level. Genotypes I and V accounted for the largest number of enterotoxigenic isolates (19 %). This study has demonstrated the genetic diversity of Jordanian clinical S. aureus isolates and shown that the presence of the toxin genes is not genotype specific. INTRODUCTIONStaphylococcus aureus produces a variety of extracellular toxins and virulence factors that contribute to its pathogenic potential. Some S. aureus strains produce pyrogenic exotoxins, such as staphylococcal enterotoxins (SEs) and toxic shock syndrome toxin-1 (Sharma et al., 2000). SEs are a group of single-chain, low-molecular-mass proteins that are similar in composition and biological activity but differ in antigenicity (Fueyo et al., 2001). Several serologically distinct SEs have been recognized, comprising the classical SEs (SEA to SEE) (Dinges et al., 2000;Becker et al., 2003) and the newly described SEs (SEG to SER and SEU) (Su & Wong, 1995;Jarraud et al., 2001;Letertre et al., 2003).The enterotoxins of S. aureus can be detected by their biological activity, by immunoassays and by PCR (McLauchlin et al., 2000). The prevalence of enterotoxigenic clinical S. aureus isolates has been reported in different countries by many investigators (Mehrotra et al., 2000;Fueyo et al., 2001;Becker et al., 2003). There are no published reports on the prevalence of these genes in Jordanian S. aureus isolates.Accurate and rapid typing of S. aureus strains is crucial to the control of infectious strains. Numerous typing methods have been described (Frénay et al., 1994;Kluytmans et al., 1995;Yoshida et al., 1997;van Leeuwen et al., 2003); among these is randomly amplified polymorphic DNA (RAPD) analysis, which has been found to be a simple, rapid and effective method for genotyping of S. aureus (Tambic et al., 1997).The purpose of this study was to investigate (i) the prevalence of the classical enterotoxin genes in Jordanian clinical isolates of S. aureus, (ii) the genetic variation among these isolates using RAPD analysis and (iii) the genotype specificity of the classical enterotoxin genes. METHODSBacterial strains. This study used 100 clinical S. aureus isolates that were collected and identified by biochemical tests during a previous study (Al-Zu'bi et al., 2004). These isolates were obtained from various clinical specimens submitted to the microbiology laboratory of Jordan University Hospital, Amman, Jordan. In all assays,...

Antibiograms, toxin profiling and molecular typing of Staphylococcus aureus isolates from two tertiary hospitals in Jordan

“…However, these results appeared to be completely different from results reported by Peles et al [45] who reported that only 15% of S. aureus isolated from milk samples in Hungary harbored at least one toxin gene indicating the low prevalence of toxin genes in non-pathogenic S. aureus isolated from milk samples. However, the results appeared different from those reported by Naffa et al [23] who showed that only 23% of the clinical isolates exhibited at least one toxin gene. The exceptionally high prevalence of toxin genes among the tested isolates in this study could be due to the nature of the tertiary hospitals in which most of the patients are referred from primary health care establishments.…”

“…The statistical program SPSS, version 20 (IBM, USA) was used for the analysis. A 0.17 and 0.30 similarity was calculated for AluI and CfoI respectively, using the method of Naffa et al [23], and was used as a discriminating threshold to define homologous clusters. Table 4 shows that 158 S. aureus isolates (63.2 %) exhibited resistance to oxacillin, while only 154 of the isolates (61.6%) were resistant to cefoxitin.…”

Occurrence of Methicillin Resistant and Enterotoxigenic Staphylococcus aureus in Traditional Cheeses in the North West of Iran

“…There are frequent reports of prevalence of S. aureus in extensively used traditional cheeses [5, 6]. Staphylococcal Enterotoxins (SEs), the main causatives for food poisoning, are a group of single chain, low molecular mass proteins and are produced during all phases of growth [7]. Based on serological classification, to date several SEs have been recognized such as SEA, SEB, SEC, SED, and SEE [8].…”

Phenotypic and Genotypic Characterization ofStaphylococcus aureusStrains from Italian Dairy Products

“…Random amplification of polymorphic DNA (RAPD PCR) has been applied extensively to distinguish different isolates of S. aureus [11, 12]. However, there is little information on the RAPD method for typing S. aureus strains isolated from dairy products.…”