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.
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ABSTRACT: Staphylococcus aureus nasal carriage is a well-defined risk factor of infection with this bacterium. The increased risk of S. aureus infection in nasal carriers is supported by the fact that the strains isolated from both colonization and infection sites are indistinguishable in most of the cases. Persistent nasal carriage seems to be associated with an increased risk of infection and this status could be defined now in clinical routine by using one or two quantitative nasal samples. There is evidence for supporting the detection of nasal carriage of S. aureus in patients undergoing cardiac surgery and in those undergoing hemodialysis in order to implement decolonization measures. More studies are needed to determine which carriers have the highest risk of infection and why decolonization strategies failed to reduce S. aureus infection in some other groups of patients.Expert Review of Anticancer Therapy 11/2013; · 3.22 Impact Factor
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ABSTRACT: To determine the long-term carriage pattern, strain relatedness and incidence of subsequent infections among methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) carriers, we screened 154 high school students for nasal carriage of S. aureus at 8 occasions during 11 months. Persistent carriage was defined as positive cultures in ≥7 occasions. Two consecutive isolates from the same subject comprised a pair, and strain relatedness was determined for each pair by molecular typings. Of 1232 nasal swab cultures obtained in 8 occasions, 323 (26.2%) were positive for S. aureus. The isolates consisted of 45 (3.7%) MRSA and 278 (22.6%) MSSA respectively from 12 and 63 subjects. Thirty-five (77.8%) MRSA isolates harbored a type IV or VT staphylococcal chromosomal cassette mec. Among 154 subjects, 52 (33.8%) were intermittent carriers. Persistent carriage was identified in 23 (14.9%) subjects and the incidence was not significantly different for MRSA carriers and MSSA carriers (3/12 [25%] versus 20/63 [31.7%], P =.7449). The MRSA and MSSA isolates were respectively comprised of 33 and 215 strain pairs. Of them, indistinguishable genotype was identified in 33 (100%) MRSA pairs and 173 (80.5%) MSSA pairs (P = .0053). Five subjects developed cellulitis and the incidence was higher for MRSA carriers (2/12, 16.7%) than for MSSA carriers (1/63, 1.58%, P = .0632) and non-carriers (2/79, 2.56%, P = .0828). In conclusion, the long-term carriage pattern in healthy individuals was similar for MRSA and MSSA. MRSA carriers were more likely to carry a single strain with a trend toward higher chance of developing cellulitis compared to MSSA carriers.Journal of clinical microbiology 05/2013; · 4.16 Impact Factor
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ABSTRACT: Observational studies have reported an inverse association between serum 25-hydroxyvitamin D (25OHD) concentrations and Staphylococcus aureus nasal carriage; however, clinical trials of vitamin D supplementation are lacking. To assess the effect of vitamin D3 supplementation on persistent S. aureus nasal carriage we conducted a randomized, double-blind, placebo-controlled trial among 322 healthy adults. Participants were given an oral dose of either 200 000 IU vitamin D3 for each of 2 months, followed by 100 000 IU monthly or placebo in an identical dosing regimen, for a total of 18 months. Nasal swabs for S. aureus culture and serum for 25OHD measurement were obtained at baseline, 6, 12 and 18 months of study. The mean baseline concentration of 25OHD was 72 nM (SD 22 nM). Vitamin D3 supplementation increased 25OHD levels which were maintained at >120 nM throughout the study. Nasal colonization by S. aureus was found in 31% of participants at baseline. Persistent carriage, defined as those that had positive S. aureus nasal cultures for all post-baseline swabs, occurred in 20% of the participants but vitamin D3 supplementation was not associated with a reduction in persistent carriage (OR = 1.39, 95% CI 0.63-3.06). Risk factor analysis showed that only gender was significantly associated with carriage, where women were less likely to be carriers than men (relative risk 0.83, 95% CI 0.54-0.99). Serum 25OHD concentrations were not associated with the risk of carriage. In conclusion, monthly administration of 100 000 IU of vitamin D3 did not reduce persistent S. aureus nasal carriage.Clinical Microbiology and Infection 07/2013; · 4.58 Impact Factor