High occurrence of staphylococcal toxins among S. aureus isolated from children with cystic fibrosis

Abstract number: 1733_1032

Alexandrou-Athanasoulis H., Petinaki E., Nikolaou S., Doudounakis S., Sergounioti A., Maniatis A., Pangalis A.

Objectives:S. aureus exerts its pathogenicity by production of staphylococcal toxins such as toxic-shock syndrome toxin (TSST-1), Panton-Valentine leucocidin, enteroto-xins etc. In this study, the occurrence of staphylococcal toxins in S. aureus stains isolated from children with cystic fibrosis was evaluated.

Material and Methods: A total of 65 S. aureus were collected between 1/1/2005 and 30/6/2006 from sputum of 65 children with cystic fibrosis (CF), aged 6.9y SD±3.7. Cultures were performed using conventional methods, while the identification of isolates was done by Gram-stain, catalase and Dnase-activity. Antimicrobial susceptibility to various antimicrobial agents was tested by the automated VITEK 2 system and the Kirby-Bauer method according to CLSI recommendations. Methicillin resistance was confirmed by the PB2a detection (Slidex bioMérieux). The detection of genes coding the toxins TSST-1, PVL, and enterotoxins (seu, sei, seg, sen, seo) was assessed by PCR. A total of 100 S. aureus, collected from different specimens of patients free cystic fibrosis were also examined.

Results: All 65 isolates were MRSA. The great majority of isolates expressed a sensitive phenotype (only resistance to oxacillin); only twelve isolates were resistant to more than three different antimicrobial agents. All isolates were found to carry at least one gene of the enterotoxin gene cluster (egc), including the genes sem, sei, seg, sen, seo; 42.5% were found to carry entire the egc operon with the co-existence of tsst-1 gene. However, none isolate was found to carry the PVL-gene. Among S. aureus from patients free cystic fibrosis, 13.7% were found to carry entire the egc operon with the co-existence of tsst-1 gene, while the presence of PVL-gene was detected in 20% of isolates.

Conclusions: These results clearly indicate that S. aureus from cystic fibrosis are potentially more virulent than other S. aureus isolates.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Location: ICC, Munich, Germany
Presentation type:
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