Community-associated Staphylococcus aureus infections and nasal carriage among children: molecular microbial data and clinical characteristics

Abstract

An increasing number of infections caused by community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) carrying the Panton-Valentine leukocidin (PVL) genes was recently identified in Greece. In the present study, 170 patients with S. aureus infections and 123 uninfected children (<15 years old) who had been tested for nasal carriage were evaluated during a 2-year period. The MecA, PVL and superantigen family genes, and MRSA clones, were investigated by molecular methods. Sites of infection and laboratory findings for patients were recorded. The results were compared and statistically analysed. Among 123 uninfected children 73 (59%) carried S. aureus, including four MRSA strains. Of these, three MRSA and three methicillin-sensitive S. aureus (MSSA) strains were PVL-positive (p <0.0001). Ninety-six patients (96/170) exhibited skin and soft-tissue infections (SSTIs), and 74 exhibited invasive infections. The incidence of staphylococcal infections increased during July to September each year. In total, 110 S. aureus isolates were PVL-positive (81 from SSTIs and 29 from invasive infections, p <0.0001). Ninety-nine out of 106 MRSA (93%) isolates from 170 patients carried the PVL genes (p <0.0001); 97 belonged to the clonal complex CC80. Leukocyte and polymorphonuclear cell counts were higher among children with MRSA infections (p <0.005). MSSA predominated among patients with invasive infections (43/74), and carried mainly genes of the superantigen family. Children <5 years of age showed a higher risk of MRSA infection. The present study demonstrates that infections due to PVL-positive CA-MRSA spread easily among children, and SSTIs can lead to invasive infections. Nasal colonization may be an additional factor contributing to the emergence of CA-MRSA.

Nasal Colonization of and Clonal Transmission of Methicillin-Susceptible Staphylococcus aureus among Chinese Military Volunteers

“…In contrast, MRSA colonization had significantly geographic distribution variations. MRSA nasal carriage rates are higher in developed countries, such as the United States (2,5,7,9,11,15,19,29,34), where soldiers who were nasal carriers of MRSA strains had a 10-fold-greater risk of clinical infection than nasal MSSA carriers in a longitudinal study (11). Other countries, such as Australia and Turkey, have had relatively rare MRSA colonization reported (21,28).…”

“…Numerous studies of S. aureus nasal carriage have been carried out in various geographic regions in the United States and the Netherlands (2,5,7,21,23,27,28,41). Cross-section surveys of nasal carriage prevalence and transmission mechanisms in special healthy populations are beneficial in assessing risk factors associated with S. aureus infections (2,8,13,26,(32)(33)(34)(35). Military facilities provide unique opportunities for studying S. aureus nasal colonization and transmission (11,19,52).…”

Lack of methicillin-resistant Staphylococcus aureus nasal carriage among patients at a primary-healthcare unit in Porto Alegre, Brazil

“…The most common site for S. aureus carriage is the nose, and nasal carriage of CA-MRSA strains is associated with a higher incidence of clinical infection 9,10,12 . Prevention of staphylococcal infections and reduction of the spread of CA-MRSA are of great importance 12 .…”

Toxin Profiling of Staphylococcus aureus Strains Involved in Varicella Superinfection

“…A major finding in this study is the high frequency of mecA, the gene conferring methicillin resistance: 19 (33%) of the 58 S. aureus isolates were mecA positive. In Europe, MRSA strains account for less than 5% of pediatric S. aureus isolates in the community setting (20,44) and for less than 11% of isolates from SSTI patients in France (10). Sixteen of the 19 MRSA isolates belonged to known C-MRSA clones.…”