Overrepresentation of the toxic shock syndrome toxin-1 gene among eldery men with bacteremic bone and joint infections caused by Staphylococcus aureus

• Staphylococcus aureus is a leading causative agent of Gram-positive septicemia. In recent years, there have been indications that both the severity and the number of staphylococcal infections have increased. In order to study the presence of genes encoding exfoliative toxins (eta/etb), Panton-Valentine leucocidin (lucS-PV-lucF-PV), and toxic shock syndrome toxin-1 (tst) in invasive isolates over time and space, 528 blood isolates of S. aureus collected during the years 2000-2012 from two Swedish university hospitals were investigated.  Age, gender and diagnosis of patients were registered, and the antibiotic susceptibility was tested. Toxin genes were detected with PCR, and the genetic relatedness was assessed with pulsed-field gel electrophoresis and whole genome sequencing. Blood cultures positive for S. aureus increased with 57.6% during the study period. Ninety-six of the isolates (18.2%) carried 97 toxin genes (one isolate carried both eta and etb). All isolates except one (PVL-producing and methicillin-resistant) were fully susceptible to the tested antibiotics. Most frequent was tst (79.4%), followed by eta (12.4%), lucS-PV-lucF-PV (7.2%), and etb (1.0%). The typical tst-positive patient was a male aged 55-74 years with a bone or joint infection. Tst-positive isolates exhibited a clear clonality, and that was independent of year and hospital. Most common was ST30-t012. To summarize, bacteremia caused by S. aureus increased during the study period, but the frequency of four important staphylococcal toxins and the antibiotic susceptibility remained low. To screen for these toxins is only cost-effective in Swedish patients with a typical clinical presentation.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Infektionsmedicin (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Infectious Medicine (hsv//eng)

Nyckelord

Mikrobiologi

Microbiology

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vet (ämneskategori)

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