Fatal S. aureus hemorrhagic pneumonia: genetic analysis of a unique clinical isolate producing both PVL and TSST-1.

In 2008, an unusual strain of methicillin-sensitive Staphylococcus aureus (MSSA68111), producing both Panton-Valentine leukocidin (PVL) and toxic shock syndrome toxin-1 (TSST-1), was isolated from a fatal case of necrotizing pneumonia. Because PVL/TSST-1 co-production in S. aureus is rare, we characterized the molecular organization of these toxin genes in strain 68111. MSSA68111 carries the PVL genes within a novel temperate prophage we call ФPVLv68111 that is most similar, though not identical, to phage ФPVL--a phage type that is relatively rare worldwide. The TSST-1 gene (tst) in MSSA68111 is carried on a unique staphylococcal pathogenicity island (SaPI) we call SaPI68111. Features of SaPI68111 suggest it likely arose through multiple major recombination events with other known SaPIs. Both ФPVLv68111 and SaPI68111 are fully mobilizable and therefore transmissible to other strains. Taken together, these findings suggest that hypervirulent S. aureus have the potential to emerge worldwide.

Necrotizing haemorrhagic pneumonia proves fatal in an immunocompetent child due to Panton-Valentine Leucocidin, toxic shock syndrome toxins 1 and 2 and enterotoxin C-producing Staphylococcus aureus.

UNLABELLED: Panton-Valentine leucocidin (PVL) toxin-producing strains of Staphylococcus aureus (S. aureus) are associated with skin abscesses and furunculosis, with necrotizing pneumonia being a relatively rare problem. Here, we describe a fatal case of necrotizing pneumonia in a 14-year-old child who presented initially with sore throat and pyrexia. He deteriorated rapidly, developing hypotension, multiple organ failure and purpura fulminans. S. aureus was isolated from the tracheal aspirate, which was found to be positive for PVL, toxic shock syndrome toxins (TSST) 1 and 2 and staphylococcal enterotoxin C (SEC). It was postulated that purpura fulminans and toxic shock syndrome were a result of the abovementioned exotoxins. CONCLUSION: This case highlights the emergence of PVL-positive community-acquired S. aureus infection and association of purpura fulminans with superantigens. Practitioners should be aware of this illness in order to initiate appropriate treatment.

Diagnostic particle agglutination using ultrasound: a new technology to rejuvenate old microbiological methods.

Microbial antigen in clinical specimens can be detected rapidly by commercial test-card latex agglutination, but poor sensitivity is a potential difficulty. Antigen detection by immuno-agglutination of coated latex micro-particles can be enhanced in comparison with the conventional test-card method in both rate and sensitivity by the application of a non-cavitating ultrasonic standing wave. Antibody-coated micro-particles suspended in the acoustic field are subjected to physical forces that promote the formation of agglutinates by increasing particle-particle contact. This report reviews the application of ultrasound to immuno-agglutination testing with several commercial antibody-coated diagnostic micro-particles. This technique is more sensitive than commercial card-based agglutination tests by a factor of up to 500 for fungal cell-wall antigen, 64 for bacterial polysaccharide and 16 for viral antigen (in buffer). The detection sensitivity of meningococcal capsular polysaccharide in patient serum or CSF has been increased to a stage where serotyping by ultrasound-enhanced agglutination is comparable to that achievable with the PCR, but is available more rapidly. Serum antigen concentration as measured by ultrasonic agglutination has prognostic value. Increasing the sensitivity of antigen detection by increasing the acoustic forces that act on suspended particles is considered. Employing turbidimetry to measure agglutination as part of an integrated ultrasonic system would enable the turnover of large numbers of specimens. Ultrasound-enhanced latex agglutination offers a rapid, economical alternative to molecular diagnostic methods and may be useful in situations where microbiological and molecular methods are impracticable.