Colonization with Staphylococcus aureus in Swedish nursing homes: A cross-sectional study

Background: Screening for bacterial colonization among risk populations could provide better estimates of the volume of the bacteria-related disease reservoir and the level of antimicrobial resistance, than do conventional laboratory reports. Methods: Two hundred and one participants at 10 Swedish nursing homes were screened for colonization with Staphylococcus aureus between January and October 2009. Of the 201 participants, 61 (30%) were male. The median age was 86 y. All participants were systematically sampled from the nasal mucosa, the pharyngeal mucosa, the groin, and active skin lesions, if any. Results: Ninety-nine of 199 participants (50%) were colonized with S. aureus. The colonization rate was 34% for the nose, 35% for throat, 10% for groin, and 54% for active skin lesions. An antibiotic-resistant S. aureus isolate was identified in 8.5% of all participants regardless of colonization status. A total of 24 resistant isolates were detected, and 21 of these were resistant to fluoroquinolones. There was no case of colonization with methicillin-resistant S. aureus (MRSA). Conclusions: The presence of resistant isolates was generally low, and the greater part of the resistance was fluoroquinolone-related. To achieve reasonable precision, screening programmes of this kind must include samples from both the nose and throat, and, although low, the prevalence of antimicrobial resistance in Swedish nursing homes still calls for reflection on how to use the fluoroquinolones wisely.