Hormonal Contraceptive Use and Persistent Staphylococcus aureus Nasal Carriage
ABSTRACT Background. Human nares colonized with Staphylococcus aureus are the most important reservoir for this pathogen. We studied the influence of sex and hormonal contraceptive use on persistent S. aureus nasal carriage.Methods. We conducted a cohort study in healthy volunteers and determined carriage status at baseline and again at follow-up by using the results of 2 swab samples at each time point. We applied logistic regression to analyze associations of interest.Results. At baseline, 266 of 1180 volunteers (22.5%) were classified as persistent nasal carriers. Compared with women not using hormonal contraceptives, women taking reproductive hormones (odds ratio [OR]. 1.88; 95% confidence interval [CI], 1.29-2.75; P = .001) and men (OR., 1.57; 95% CI, 1.08-2.28; P = .02) were more likely to be persistent carriers. These associations remained stable after adjusting for known risk factors of nasal carriage. Women taking hormonal contraceptives and being persistent carriers at baseline were more likely to remain carriers after a median follow-up time of 70 days than women not using such medication (OR, 3.25; 95% CI, 1.44-7.34; P = .005). No patterns of association could be observed between persistent carriage among women and type of progestin or dose of estrogen used. Assuming causality and using estimates from multivariable logistic regression, we approximated that 20% (95% CI, 2.4%-34.9%) of persistent nasal carriage among women represented by our sample is attributable to hormonal contraception (population-attributable fraction).Conclusions. The widespread use of hormonal contraception may substantially increase the human S. aureus reservoir with potential impact on S. aureus infection and transmission.
Infection Control and Hospital Epidemiology 09/2014; 35(9):1192-1194. DOI:10.1086/677627 · 3.94 Impact Factor
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ABSTRACT: Nasal carriage of Staphylococcus aureus is a risk factor for infection, yet the bacterial determinants required for carriage are poorly defined. Interactions between S. aureus and other members of the bacterial flora may determine colonisation and were inferred in previous studies using correlated species distributions. However, traits mediating species interactions are often polymorphic, suggesting that understanding how interactions structure communities requires a trait-based approach. We characterised S. aureus growth inhibition by the culturable bacterial aerobe consortia of 60 nasal microbiomes, revealing intraspecific variation in growth inhibition and that inhibitory isolates clustered within communities that were culture-negative for S. aureus. Across microbiomes, the cumulative community-level growth inhibition was negatively associated with S. aureus incidence. To fully understand the ecological processes structuring microbiomes it will be crucial to account for intraspecific variation in the traits mediating species interactions.Infection and Immunity 06/2014; 82(9). DOI:10.1128/IAI.02025-14 · 4.16 Impact Factor
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ABSTRACT: Objective: The findings from truly randomized community-based studies on Staphylococcus aureus nasal colonization are scarce. Therefore we have examined point prevalence and risk factors of S. aureus nasal carriage in a non-hospitalized population of Braunschweig, northern Germany. Methods: A total of 2026 potential participants were randomly selected through the resident's registration office and invited by mail. They were requested to collect a nasal swab at home and return it by mail. S. aureus was identified by culture and PCR. Logistic regression was used to determine risk factors of S. aureus carriage. Results: Among the invitees, 405 individuals agreed to participate and 389 provided complete data which was included in the analysis. The median age of the participants was 49 years (IQR: 39-61) and 61% were females. S. aureus was isolated in 85 (21.9%; 95% CI: 18.0-26.2%) of the samples, five of which were MRSA (1.29%; 95% CI: 0.55-2.98%). In multiple logistic regression, male sex (OR = 3.50; 95% CI: 2.01-6.11) and presence of allergies (OR = 2.43; 95% CI: 1.39-4.24) were found to be associated with S. aureus nasal carriage. Fifty five different spa types were found, that clustered into nine distinct groups. MRSA belonged to the hospital-associated spa types t032 and t025 (corresponds to MLST CC 22), whereas MSSA spa types varied and mostly belonged to spa-CC 012 (corresponds to MLST CC 30), and spa-CC 084 (corresponds to MLST CC 15). Conclusion: This first point prevalence study of S. aureus in a non-hospitalized population of Germany revealed prevalence, consistent with other European countries and supports previous findings on male sex and allergies as risk factors of S. aureus carriage. The detection of hospital-associated MRSA spa types in the community indicates possible spread of these strains from hospitals into the community.PLoS ONE 09/2014; 9(9):e107937. DOI:10.1371/journal.pone.0107937 · 3.53 Impact Factor