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Applied and Environmental Microbiology, November 2009, p. 6839-6849, Vol. 75, No. 21
0099-2240/09/$08.00+0 doi:10.1128/AEM.00272-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
Diverse Enterotoxin Gene Profiles among Clonal Complexes of Staphylococcus aureus Isolates from the Bronx, New York
,
Avanish K. Varshney,1,
José R. Mediavilla,2,
Natalie Robiou,3
Alice Guh,4
Xiabo Wang,1
Philip Gialanella,4,5
Michael H. Levi,4,5
Barry N. Kreiswirth,2 and
Bettina C. Fries1,4*
Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York,1 Public Health Research Institute, University of Medicine and Dentistry of New Jersey, International Center for Public Health, Newark, New Jersey,2 Fordham University, Bronx, New York,3 Infectious Disease Division of Montefiore Medical Center, Bronx, New York,4 Department of Clinical Microbiology Montefiore Medical Center, Bronx, New York5
Received 3 February 2009/ Accepted 1 September 2009
Staphylococcal enterotoxins (SE) can cause toxin-mediated disease, and those that function as superantigens are implicated in the pathogenesis of allergic diseases. The prevalence of 19 enterotoxin genes was determined by PCR in clinical S. aureus strains derived from wounds (108) and blood (99). We performed spa typing and multilocus sequence typing (MLST) to determine clonal origin, and for selected strains staphylococcal enterotoxin B (SEB) production was measured by enzyme-linked immunosorbent assay. Strains carried a median of five SE genes. For most SE genes, the prevalence rates among methicillin-resistant and methicillin-sensitive S. aureus isolates, as well as wound- and blood-derived isolates, did not differ. At least one SE gene was detected in all except two S. aureus isolates (>99%). Complete egc clusters were found in only 11% of S. aureus isolates, whereas the combination of sed, sej, and ser was detected in 24% of clinical strains. S. aureus strains exhibited distinct combinations of SE genes, even if their pulsed-field gel electrophoresis and MLST patterns demonstrated clonality. USA300 strains also showed considerable variability in SE content, although they contained a lower number of SE genes (mean, 3). By contrast, SE content was unchanged in five pairs of serial isolates. SEB production by individual strains varied up to 200-fold, and even up to 15-fold in a pair of serial isolates. In conclusion, our results illustrate the genetic diversity of S. aureus strains with respect to enterotoxin genes and suggest that horizontal transfer of mobile genetic elements encoding virulence genes occurs frequently.
* Corresponding author. Mailing address: Albert Einstein College of Medicine, Department of Medicine, Microbiology and Immunology, 1300 Morris Park Ave., Bronx, NY 10461. Phone: (718) 430-2365. Fax: (718) 430-8968. E-mail: bettina.fries{at}einstein.yu.edu
Published ahead of print on 11 September 2009.
Supplemental material for this article may be found at http://aem.asm.org/.
A.K.V. and J.R.M. contributed equally to this study.
Applied and Environmental Microbiology, November 2009, p. 6839-6849, Vol. 75, No. 21
0099-2240/09/$08.00+0 doi:10.1128/AEM.00272-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
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