Abstract
Background Staphylococcus aureus is an important cause of infection, particularly in persons colonized with this organism. This study compared the annual prevalence and microbiological characteristics of methicillin-resistant S. aureus (MRSA) nasal colonization in Taiwanese children from 2004 through 2009. Risk factors for MRSA were determined for the overall study period.MethodsChildren from birth to ≤14 years of age presenting for health maintenance visits or attending 1 of 57 kindergartens were recruited. Nasal swabs were obtained, and a questionnaire was administered. The prevalence and microbiological characteristics of MRSA colonization were also calculated for two 3-year periods: 2004–2006 and 2007–2009.ResultsCultures of the anterior nares were positive for S. aureus in 824 (25.8%) of the 3,200 children, and MRSA colonization was found in 371 (11.6%) children. The prevalence of S. aureus colonization decreased from 28.1% in 2004–2006 to 23.3% in 2007–2009 (p<0.01), whereas the prevalence of MRSA colonization increased from 8.1% to 15.1% during this period (p<0.0001). Multivariate analysis revealed that the independent risk factors for MRSA carriage were different for male and female children, and also among age groups. Most MRSA isolates belonged to sequence type 59 (ST59) (86.3%); however, a multiresistant MRSA clone with ST338 background emerged in 2007–2009. Ten (62.5%) of the 16 MRSA isolates expressed the genotypic profile ST338/staphylococcal cassette chromosome mec VT/Panton-Valentine leukocidin-positive/staphylococcal enterotoxin B-positive, and differed only in their antimicrobial susceptibility patterns.ConclusionThe prevalence of nasal colonization by MRSA increased among healthy Taiwanese children from 2004–2006 to 2007–2009, despite an overall decrease in the prevalence of nasal colonization by S. aureus. A multiresistant MRSA clone characterized as ST338 was identified from these children.
Highlights
Staphylococcus aureus is a common human pathogen of skin infections and invasive diseases in all age groups, such as pneumonia, osteomyelitis, and endocarditis, in healthcare and community settings [1]
CA-methicillin-resistant S. aureus (MRSA) strains were thought to lack an association with healthcare settings and to have unique microbiologic characteristics such as limited antibiotic resistance, different exotoxin gene profiles (e.g., Panton-Valentine leukocidin, PVL), and smaller staphylococcal cassette chromosome mec (SCCmec) type IV [9]
In Taiwan, MRSA strains of sequence type 59 (ST59), determined by multilocus sequence typing (MLST) and carrying type IV or a variant, type VT SCCmec elements, were found to be the major strains of CAMRSA [13,14,15,16,17,18]
Summary
Staphylococcus aureus is a common human pathogen of skin infections and invasive diseases in all age groups, such as pneumonia, osteomyelitis, and endocarditis, in healthcare and community settings [1]. CA-MRSA strains were thought to lack an association with healthcare settings and to have unique microbiologic characteristics such as limited antibiotic resistance (except to b-lactam antimicrobial agents), different exotoxin gene profiles (e.g., Panton-Valentine leukocidin, PVL), and smaller staphylococcal cassette chromosome mec (SCCmec) type IV [9]. These epidemic strains have been shown to be transmitted in healthcare settings and to exhibit emerging resistance to non-b-lactam agents [10,11,12]. Risk factors for MRSA were determined for the overall study period
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