Throat swabs should be included in S. aureus screening programs

By Nikki Withers, medwireNews Reporter

Performing throat swabs, in addition to nasal swabs, in Staphylococcus aureus screening programs may improve rates of detection, suggest study findings.

"Our data confirm that nasal screening will identify the majority of S. aureus carriers. However, nearly one third of our S. aureus carriers would have been missed had we not collected throat swabs," say Tara Smith (University of Iowa, USA) and team.

Previous studies have identified the anterior naris as the most common location for S. aureus colonization, and thus the most appropriate location for screening swabs. However, recent studies have cast doubt on this practice.

To investigate further, the researchers combined the results of two cross-sectional studies to evaluate the location of S. aureus colonization in individuals outside of the healthcare setting.

A total of 340 participants were included in the study. The mean age of the participants was 39.3 years and 75.9% were female.

In all, 103 (30.3%) of participants were S. aureus carriers, including 31 (30.1%) exclusive throat carriers, 44 (42.7%) exclusive nose carriers, and 28 (27.2%) carriers at both sites.

This, say Smith et al, indicates that a substantial proportion of positive participants would have tested negative had throat cultures not been included.

Throat colonization was much more prevalent in the younger participants; 28.1% of the participants aged less than 30 years were throat carriers compared with 7.1% of those over 30 years of age.

"Interestingly, we did not observe the same trend for nasal colonization; exclusive nasal colonization rates were consistent across age groups," says the research team.

Non-White race was found to be a predictor of both exclusive throat and nasal carriage (odds ratio=4.91 and 5.14, respectively).

Sampling season was also associated with exclusive nasal carriage, with a significantly higher prevalence in samples collected during the spring and summer months, whereas there was no significant association between sampling season and exclusive throat carriage.

"Our findings suggest that including a throat swab in addition to a nasal swab could play an important role in the success of active surveillance cultures programs and population-based surveys, particularly when administered to community residents with limited exposure to health care," concludes the team in the American Journal of Infection Control.

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