Illness Severity in Community-Onset Invasive Staphylococcus aureus Infection and the Presence of Virulence Genes

Abstract

Background. It is uncertain whether particular clones causing invasive community-onset methicillin-resistant and methicillin-sensitive Staphylococcus aureus (cMRSA/cMSSA) infection differ in virulence.Methods. Invasive cMRSA and cMSSA cases were prospectively identified. Principal component analysis was used to derive an illness severity score (ISS) from clinical data, including 30-day mortality, requirement for intensive hospital support, the presence of bloodstream infection, and hospital length of stay. The mean ISS for each S. aureus clone (based on MLST) was compared with its DNA microarray-based genotype.Results. Fifty-seven cMRSA and 50 cMSSA infections were analyzed. Ten clones caused 82 (77%) of these infections and had an ISS calculated. The enterotoxin gene cluster (egc) and the collagen adhesin (cna) gene were found in 4 of the 5 highest-ranked clones (ST47-MSSA, ST30-MRSA-IV[2B], ST45-MSSA, and ST22-MRSA-IV [2B]) compared with none and 1 of the lowest 5 ranked clones, respectively. cMSSA clones caused more severe infection than cMRSA clones. The lukF/lukS Panton-Valentine leukocidin (PVL) genes did not directly correlate with the ISS, being present in the second, fourth, and 10th most virulent clones.Conclusions. The clinical severity of invasive cMRSA and cMSSA infection is likely to be attributable to the isolates' entire genotype rather than a single putative virulence determinant such as PVL.

Clinical and molecular characteristics of invasive community-acquired Staphylococcus aureusinfections in Chinese children

“…Our previous study also revealed that ST59 was the dominant clone in children from the mainland of China, which was in agreement with the results reported by Taiwan [20]. However, no dominant clone has been detected yet for invasive MSSA isolates throughout the world [21],[22]. …”

Outcomes and Treatment of Chronic Methicillin-ResistantStaphylococcus aureusDiffers by Staphylococcal Cassette Chromosomemec(SCCmec) Type in Children With Cystic Fibrosis

“…However, outcomes associated with different SCCmec types have not been addressed in CF patients with chronic lung infections, and SCCmec status is not currently used in clinical care. Nonetheless, because SCCmec II encodes for more antibiotic resistance genes [18,19], there may be a poor response to oral antibiotics or choices may be limited; thus, the question arises whether knowledge of the SCCmec type would be relevant to care.…”

Successful management of Panton-Valentine leukocidine-positive necrotising pneumonia and A/H1N12009influenzavirus coinfection in adult

“…The association of the PVL with virulence remains controversial. Indeed, several studies describe PVL as an independent indicator of virulence10 17 and other authors attribute the virulence of S. aureus to the isolates’ entire genotype 18 19. All data suggest that the PVL contributes to the S. aureus pathogenesis but the importance of PVL in virulence must be elucidated.…”