Sex differences in the risk factors for Staphylococcus aureus throat carriage

Background Male gender and adiposity are considered to be risk factors for Staphylococcus aureus carriage. We tested whether colonization is related to free testosterone (fT) level and adiposity, measured with body mass index (BMI) and body fat percentage (BFP), in healthy adults. Methods Blood sample and throat swabs were taken twice (at 4-week intervals) from healthy men and women aged 18-36 years. fT level, height, weight, and BFP were measured. Participants were classified as persistent carriers, intermittent carriers (excluded from the analyses), and noncarriers. The final sample was 152 participants: 85 men and 67 women. Results BFP, but not BMI, correlated positively with S aureus colonization ( P = .02) in men. BMI became a significant predictor of carriage only when comparing groups within and above norms ( P = .04). There was no relationship for BMI nor BFP in women. Higher fT level was related to persistent carriage ( P = .02) in women, there was no relationship for fT level in men. Conclusion Risk factors for S aureus carriage are sex dependent. Within-sex variation in colonization is related to fT level in women, whereas in men it is related to the amount of body fat.