Prevalence of Nasal Carriage of S aureus in Children

Abstract

Asymptomatic carriage of Staphylococcus aureus is common, particularly in the anterior part of the nasal cavity. Apart from nasal and nasopharyngeal carriage, another frequent site for S aureus colonization is the skin, particularly the inguinal fold, rectum and axilla. The general prevalence of S aureus carriage is around 20-30% as reported by relevant studies in field literature. In children, data on nasal carriage appears to be somewhat similar to the prevalence reported in adults, ranging from 18.12 to 38.5 percent, but there are certain particularities and a wide variability between results from different countries and different studies. To determine the real prevalence of S aureus and MRSA strains, studies should adjust for confounding factors, as described in this article.

Asymptomatic carriage of Staphylococcus aureus is especially common, particularly in the anterior part of the nasal cavity, where a prevalence rate of around 20% has been reported [1]. Available literature data for S aureus nasal colonization in the USA showed a 32.4% prevalence of S aureus and 0.8% for methicillin- resistant S aureus (MRSA) during 2000-2001 [2], with similar data for 2006: 31.6% and 0.84%, respectively [3]. In the UK, data from 1998 identified a 23% prevalence of S aureus (1.5% MRSA) [4] while a study performed in elderly residents care homes performed during 2006- 2009 reported rates of 19-22% [5]. More recent data from a cross-sectional study in 32 206 subjects from nine European countries (Austria, Belgium, Croatia, France, Hungary, Spain, Sweden, the Netherlands, UK) revealed a prevalence of 21.6% for S aureus and 0.28% for MRSA [6].

Apart from nasal and nasopharyngeal carriage, another common site for S aureus colonization is the skin, particularly the inguinal fold [7], rectum and axilla [8]. The bacterial strains can display an altered antibiotic sensitivity profile, particularly in elderly patients, with comorbid diseases, causes of immune suppression, previous antibiotherapy or history of prior hospital admission during the pasts months [9].

In children, data on nasal carriage appears to be somewhat similar to the prevalence reported in adults, but there are certain particularities, better described in the Table below. One particular study identified the main risk factor for MRSA carriage in children as having a parent with MRSA carriage [10].

Data on nasal carriage of S aureus is quite polymorphic and the results of epidemiological studies can vary based on a large number of intrinsic factors, such as: timeline of sample collection, season of sample collection, characteristics of subjects included in the study (data from day care centers, kindergartens, schools, versus data from stay-at-home children), age of study subjects, culture and identification technique, and so on. To determine the prevalence of S aureus and MRSA strains with a higher accuracy, studies should adjust for factors which might have a significant impact on study results, as described above.

Table. Studies describing the prevalence of S aureus and MRSA strains in children.

Table. Studies describing the prevalence of S aureus and MRSA strains in children.