High serum 25-hydroxyvitamin D is associated with a low incidence of stress fractures.

Low serum 25-hydroxyvitamin D [25(OH)D] concentrations are associated with hip fractures, but the dose-response relationship of serum 25(OH)D with risk of stress fractures in young women is unknown. This nested case-control study in a cohort of female Navy recruits was designed to determine whether those with low prediagnostic serum 25(OH)D concentrations had greater risk of stress fracture. Sera were drawn in 2002-2009 from 600 women who were diagnosed subsequently with stress fracture of the tibia or fibula and 600 matched controls who did not experience a stress fracture. The 25(OH)D concentration was measured using the DiaSorin radioimmunoassay method. Controls were individually matched to cases on race (white, black, or other), length of service (±30 days), and day blood was drawn (±2 days). There was approximately half the risk of stress fracture in the top compared with the bottom quintile of serum 25(OH)D concentration (odds ratio [OR] = 0.51, 95% CI 0.34-0.76, p ≤ 0.01). The range of serum 25(OH)D in the lowest quintile was 1.5 to 19.7 (mean 13.9) ng/mL, whereas in the highest it was 39.9 to 112 (mean 49.7) ng/mL. It is concluded that there was a monotonic inverse dose-response gradient between serum 25(OH)D and risk of stress fracture. There was double the risk of stress fractures of the tibia and fibula in women with serum 25(OH)D concentrations of less than 20 ng/mL compared to those with concentrations of 40 ng/mL or greater. A target for prevention of stress fractures would be a serum 25(OH)D concentration of 40 ng/mL or greater, achievable with 4000 IU/d of vitamin D(3) supplementation.

Increasing rates of community-acquired methicillin-resistant Staphylococcus aureus infections among HIV-infected persons.

Community-acquired (CA) methicillin-resistant Staphylococcus aureus (MRSA) rates have rapidly increased in the general population; however, little data on recent incidence rates and risk factors of CA-MRSA infections among HIV patients appear in the literature. A retrospective study was conducted from 1993 through 2005 among patients at a large HIV clinic. Trends in CA-MRSA infection incidence rates, clinical characteristics and risk factors for CA-MRSA were evaluated. Seven percent of our cohort developed a CA-MRSA infection during the study period. The rate of CA-MRSA infections among HIV-infected population significantly increased since 2003, with an incidence of 40.3 cases/1000 person-years in 2005, which was 18-fold higher than the general population served at our facility. In all, 90% of infections were skin/soft tissue infections with a predilection for buttock or scrotal abscess formation; 21% of patients experienced a recurrent infection. Risk factors included a low CD4 count at the time of infection (odds ratio [OR] per 100 CD4 cells 0.84, P = 0.03), high maximum log(10) HIV viral load (OR 4.54, P<0.001), recent use of beta-lactam antibiotics (OR 6.0 for receipt of two prescriptions, P<0.001) and a history of syphilis (OR 4.55, P = 0.01). No patient receiving trimethoprim-sulfamethoxazole prophylaxis developed a CA-MRSA infection. Over the study period, CA-MRSA accounted for an increasing percentage of positive wound cultures and Staphylococcus aureus isolates, 37% and 65%, respectively, during 2005. In conclusion, CA-MRSA infections have rapidly increased among HIV-infected patients, a group which has a higher rate of these infections than the general population. Risk factors for CA-MRSA among HIV-infected patients include low current CD4 cell count, recent beta-lactam antibiotic use and potentially high-risk sexual activity as demonstrated by a history of syphilis infection.