A Multicenter, Cross‐Sectional Study on the Prevalence and Risk Factors for Nasal Colonization with<i>Staphylococcus aureus</i>in Patients Admitted to Children’s Hospitals in Switzerland

“…S. aureus nasal carriage decreases in the first year of life (Peacock et al 2003;Lebon et al 2008), but increases again around the age of three, peaking at approximately 50 % in the pre-teen years (Bogaert et al 2004;Datta et al 2008). In children the prevalence of S. aureus appears inversely related to the prevalence of Streptococcus pneumonia (Bogaert et al 2004).…”

Section: Carriage and Colonizationmentioning

confidence: 99%

Infection control of Staphylococcus aureus : spa typing to elucidate transmission

Mernelius¹

2015

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Staphylococcus aureus is a commensal of the human flora, primarily colonizing the anterior nares and throat, but it may also cause infections ranging from mild skin and soft tissue infections to severe diseases such as endocarditis and septicemia. S. aureus is also a major nosocomial problem increasing with the worldwide dissemination of methicillin-resistant S. aureus (MRSA).The main vector for bacterial cross-transmission in healthcare settings is the hands of healthcare workers (HCWs). No S. aureus was detected in the air in this thesis demonstrating that transmission through air is not important. Despite the fact that good compliance with hand hygiene is essential to prevent cross-transmission the compliance is generally less than 50 %.Gold standard to track bacterial transmission in healthcare settings has for long been pulsedfield gel electrophoresis (PFGE), a method that is labor-intensive, lacks consensus protocol and relies on semi-subjective analysis. Molecular typing by sequencing of the hypervariable part of the S. aureus protein A gene (spa typing) has overcome these problems and has shown promising results in epidemiological investigations.The aims of this thesis were to study bacterial transmission with S. aureus colonization of newborn infants as a model and to evaluate spa typing as a molecular tool. Additionally, the influence of compliance with hygiene guidelines on S. aureus transmission was assessed.Analysis of 280 MRSA isolates by spa typing revealed excellent typeability and epidemiological concordance and satisfactory discriminatory power. Additionally, spa typing was considered superior to PFGE thanks to its accessibility, ease of use and rapidity. Also, spa typing results are registered in a global database, facilitating inter-laboratory comparison.The prevalence of S. aureus ranged from 41 % to 66 % in the populations studied and males had the highest colonization rate. Throat was the premier colonization site for adults and transmission from individuals colonized in the throat only was documented, suggesting that throat cultures should be included in S. aureus screening programs. The umbilicus was the premier colonization site for newborn infants. Incubating the swabs in enrichment broth prior to plating increased the prevalence of S. aureus positive samples by 46 %, resulting in prevalence viii ranging from 51 % to 70 % in the populations studied. Thus enrichment prior to plating is necessary to determine more truthful S. aureus colonization rates. There were no indications of an institutional flora, as the colonization rates, spa type distribution and antibiotic resistance prevalence were similar among parents and HCWs.Direct observations and self-reporting by HCWs were both validated as tools for monitoring compliance with hygiene guidelines. The compliance with hygiene guidelines was significantly higher following a 10-point hygiene intervention as compared to baseline. The compliance was also higher three years after the intervention in three of four participating departm...

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“…In the paediatric population, prevalence has been documented in specific countries but, to date, no systematic description of the molecular epidemiology has ever been performed on carriage isolates. In the present study, we performed extensive molecular characterization of MSSA carriage isolates, benefiting from a prospective multicentre Swiss study in children [13]. The analysis revealed an unsuspected genome-content diversity among the S. aureus strains not only across eight participating Swiss children's hospitals, but also within each studied centre.…”

Section: Introductionmentioning

confidence: 97%

Molecular epidemiology of the nasal colonization by methicillin-susceptible Staphylococcus aureus in Swiss children

Megevand

Gervaix

Heininger

et al. 2010

Clinical Microbiology and Infection

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Nasal carriage of Staphylococcus aureus contributes to an increased risk of developing an infection with the same bacterial strain. Genetic regulatory elements and toxin-expressing genes are virulence factors associated with the pathogenic potential of S. aureus. We undertook an extensive molecular characterization of methicillin-susceptible S. aureus (MSSA) carried by children. MSSA were recovered from the nostrils of children. The presence of Panton-Valentine leukocidin (PVL), exfoliatins A and B (exfoA and exfoB), and the toxic-shock staphylococcal toxin (TSST-1) and agr group typing were determined by quantitative PCR. A multiple-locus variable-number of tandem repeat analysis (MLVA) assay was also performed for genotyping. Five hundred and seventy-two strains of MSSA were analysed. Overall, 30% were positive for toxin-expressing genes: 29% contained one toxin and 1.6% two toxins. The most commonly detected toxin gene was tst, which was present in 145 (25%) strains. The TSST-1 gene was significantly associated with the agr group 3 (OR 56.8, 95% CI 32.0-100.8). MLVA analysis revealed a large diversity of genetic content and no clonal relationship was demonstrated among the analysed MSSA strains. Multilocus sequence typing confirmed this observation of diversity and identified ST45 as a frequent colonizer. This broad diversity in MSSA carriage strains suggests a limited selection pressure in our geographical area.

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A Multicenter, Cross‐Sectional Study on the Prevalence and Risk Factors for Nasal Colonization withStaphylococcus aureusin Patients Admitted to Children’s Hospitals in Switzerland

Cited by 13 publications

References 12 publications

Duration of methicillin-resistant Staphylococcus aureus colonization after diagnosis: A four-year experience from southern Sweden

Duration of methicillin-resistant Staphylococcus aureus colonization after diagnosis: A four-year experience from southern Sweden

Infection control of Staphylococcus aureus : spa typing to elucidate transmission

Molecular epidemiology of the nasal colonization by methicillin-susceptible Staphylococcus aureus in Swiss children

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