Methicillin-susceptible, non-multiresistant methicillin-resistant and multiresistant methicillin-resistant Staphylococcus aureus infections: a clinical, epidemiological and microbiological comparative study

Abstract

Non-multiresistant methicillin-resistant Staphylococcus aureus (nmMRSA) infections are emerging worldwide and are often community-associated. This prospective case-cohort study compares features of 96 nmMRSA clinical isolates with 96 matched multiresistant MRSA (mMRSA) and 192 matched methicillin-susceptible S. aureus (MSSA) clinical isolates. Seventy-four percent of nmMRSA infections were healthcare-associated. nmMRSA infections were much more likely to involve skin and soft tissue (skin and soft tissue infections; SSTIs) and were much less likely to be treated appropriately with antibiotics than MSSA or mMRSA infections. Panton-Valentine leukocidin (PVL) genes were detected in 55% of nmMRSA, 16% of MSSA and 2% of mMRSA isolates. Independent of the methicillin-resistance phenotype, 59% of PVL-positive SSTIs presented as furunculosis compared to only 10% of PVL-negative SSTIs. Patients with PVL-positive infections were much younger than patients with PVL-negative infections. The proportion of PVL-positive infections peaked in the 10-29 years old age group, followed by a linear decline.

A Histidine-to-Arginine Substitution in Panton-Valentine Leukocidin from USA300 Community-Acquired Methicillin-Resistant Staphylococcus aureus Does Not Impair Its Leukotoxicity

“…Altogether, these data suggest that the PVLs produced by each CA-MRSA and MSSA lineage are equally leukotoxic. This in vitro observation is in accordance with clinical observations that PVLs impact on the severity of human skin and soft tissue infections, necrotizing pneumonia, and bone and joint infections regardless of the genetic background and the mecA status of the isolated strains (3,11,20).…”

Panton-Valentine Leukocidin-Positive Staphylococcus aureus in Ireland from 2002 to 2011: 21 Clones, Frequent Importation of Clones, Temporal Shifts of Predominant Methicillin-Resistant S. aureus Clones, and Increasing Multiresistance

“…CC/ST59-MRSA-V is among the predominant CA-MRSA clones in some northern European countries (21). In contrast, similar to in the present study, ST93-MRSA-IV has only been reported sporadically in Europe (21,53) but is the dominant pvl-positive MRSA strain in Australia, where it has spread into health care facilities (54). Increasing reports of outbreaks of pvl-positive MRSA, particularly in NICUs, highlights the ability of these strains to spread among vulnerable patient groups in hospitals (24,25,47,48).…”

Incidence, Risk Factors, and Outcomes of Panton-Valentine Leukocidin-Positive Methicillin-Susceptible Staphylococcus aureus Infections in Auckland, New Zealand

“…However, other studies that used a methodology similar to that of our study reported much lower prevalence rates, ranging from 7 to 12% (13,21,29). In Auckland, PVL-positive MSSA was strongly associated with the diagnosis of SSTI; 48% of all MSSA isolates associated with SSTI were lukSF-PV positive.…”