BackgroundThe present study aimed to identify risk factors for preoperative nasal carriage of resistant bacteria - MRSA methicillin-resistant Staphylococcus (S.) aureus, MRSE (methicillin-resistant Staphylococcus epidermidis), and MRCNS (methicillin-resistant coagulase negative staphylococci) in total hip and knee arthroplasty (THA and TKA) patients. MethodsNasal cultures were obtained from 538 patients before THA (262 primary and 26 revision) and TKA (241 primary and 9 revision). These were classified either as methicillin-resistant bacteria (group MR) or methicillin-susceptible bacteria (including culture-negative) (group MS). Patient characteristics were compared between these groups using logistic regression models. ResultsThe resistant bacteria were preoperatively present in 33.1% (178 patients) among all patients. MRSE, MRCNS, and MRSA were detected in 27.5% (148 patients), 3.7% (20 patients), and 1.9% (10 patients). In the unadjusted comparisons of the patient characteristics between the groups MR and MS, a significant difference was found in the percentages of diabetic patients (15.2% vs. 9.2%, P = 0.04); the association remained after the multivariable adjustment for possible risk factors (P < 0.001). In addition, the diabetic patients in the group MR showed a higher percentage of receiving insulin injection than those in the group MS (25.9% vs. 6.1%, P = 0.063), and their mean levels of HbA1c were significantly higher in the group MR than the MS (6.8% vs. 6.4%, P = 0.03). ConclusionsWe identified diabetes as a risk factor for the preoperative nasal carriage of resistant bacteria. Our results suggest that, in order to prevent a surgical site infection (SSI), extra care should be taken in performing joint arthroplasties for diabetic patients, especially using insulin and with high HbA1c levels (≥6.6%) prior to the surgical procedures.