What is the most cost-effective strategy for nasal screening and Staphylococcus aureus decolonization in patients undergoing total hip arthroplasty?

BACKGROUND: To reduce periprosthetic joint infection after total hip arthroplasty (THA), several nasal screening and decolonization strategies for methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive Staphylococcus aureus (MSSA) have been performed. These include universal decolonization (UD; i.e., no screening and decolonization for all patients), universal screening and target decolonization (US; i.e., screening for all patients and decolonization for bacterial positive patients), and target screening and decolonization (TS; i.e., screening and decolonization for high-risk populations only). Although TS is the most cost-effective strategy, useful risk factors must be identified. The purpose of this study was to evaluate the presence of predictive factors that enable the TS strategy to be successfully implemented and to compare the costs of each strategy. METHODS: A total of 1654 patients scheduled for primary or revision THA (1464 female, 190 male; mean age 64 years) were screened prior to surgery for bacterial colonization of the nasal mucosa. Risk factors for positive MRSA and S. aureus (including both MRSA and MSSA) tests were analyzed according to the following parameters: sex, age ≥ 80 years, body mass index ≥ 30 kg/m2, antibiotic use within 3 years, corticosteroid use, serum albumin < 3.5 g/dL, glomerular filtration rate < 50 mL/min, presence of brain, thyroid, cardiac, or pulmonary disease, diabetes, asthma, smoking status, and whether revision surgery was performed. The average cost of each strategy was calculated. RESULTS: In total, 29 patients (1.8 %) tested positive for MRSA and 445 (26.9 %) tested positive for S. aureus. No parameters were identified as independent risk factors for MRSA and only female sex was identified as a risk factor for S. aureus (p = 0.003; odds ratio: 1.790; 95 % confidence interval: 1.210-2.640). The average cost of each strategy was 1928.3 yen for UD, 717.6 yen for US, and 717.6 yen for TS (for eradicating MRSA), and 1928.3 yen for UD, 1201.6 yen for US, and 1160.4 yen for TS (for eradicating S. aureus). CONCLUSIONS: No useful predictive parameters for implementing the TS strategy were identified. Based on cost implications, US is the most cost-effective strategy for THA patients.

Can sterility of stripped iodophor-impregnated plastic adhesive drape be maintained at the time of incision closure in total hip arthroplasty?

OBJECTIVE: The aim of this study was to analyze the contamination rates of the skin under the iodophor-impregnated plastic adhesive drape (IOD) at the time of incision closure in total hip arthroplasty (THA). METHODS: A total of 225 patients undergoing primary THA (28 men, 197 women; mean age=65 years; age range=30-85) were included in this study. After asepsis using a solution of 1% chlorhexidine with 83% alcohol by volume, the surgical site was painted with a 10% povidone-iodine solution, and IOD was attached tautly at the start of surgery. Swabs of the surgical site were collected as follows: swab A from the skin before IOD application, swab B from the surface of the IOD at the time of incision closure, and swab C from the skin after peeling back the IOD. The obtained samples were promptly sent for microbiological analysis. The contamination rate was determined for swabs A, B, and C, and the contamination rate of swab C was compared with that of swabs A and B, and the bacterial species were identified. RESULTS: Positive cultures were seen in 8 cases (3.6%) for swab A, 10 cases (4.4%) for swab B, and 22 cases (9.8%) for swab C. The contamination rate of swab C was significantly higher than that of swabs A (p=0.008) and B (p=0.028). Coagulase-negative Staphylococcus (n=10) and Cutibacterium acnes (n=7) were the most frequently cultured microorganisms from swab C. CONCLUSION: In THA, the contamination rate of the skin after peeling off the IOD before incision closure was higher than that of the skin immediately after sterilization with povidone-iodine and higher than that on the IOD at the time of incision closure. The detected bacterial species were considered clinically significant pathogens. Preventive measures against infection, such as minimizing stripping of the IOD or re-sterilizing bare skin after IOD stripping, should be instituted in consideration of these findings when performing THA using IOD.

Redundant and Distinct Roles of Secreted Protein Eap and Cell Wall-Anchored Protein SasG in Biofilm Formation and Pathogenicity of Staphylococcus aureus.

Chronic and fatal infections caused by Staphylococcus aureus are sometimes associated with biofilm formation. Secreted proteins and cell wall-anchored proteins (CWAPs) are important for the development of polysaccharide-independent biofilms, but functional relationships between these proteins are unclear. In the present study, we report the roles of the extracellular adherence protein Eap and the surface CWAP SasG in S. aureus MR23, a clinical methicillin-resistant isolate that forms a robust protein-dependent biofilm and accumulates a large amount of Eap in the extracellular matrix. Double deletion of eap and sasG, but not single eap or sasG deletion, reduced the biomass of the formed biofilm. Mutational analysis demonstrated that cell wall anchorage is essential for the role of SasG in biofilm formation. Confocal laser scanning microscopy revealed that MR23 formed a rugged and thick biofilm; deletion of both eap and sasG reduced biofilm ruggedness and thickness. Although sasG deletion did not affect either of these features, eap deletion reduced the ruggedness but not the thickness of the biofilm. This indicated that Eap contributes to the rough irregular surface structure of the MR23 biofilm and that both Eap and SasG play roles in biofilm thickness. The level of pathogenicity of the Δeap ΔsasG strain in a silkworm larval infection model was significantly lower (P < 0.05) than those of the wild type and single-deletion mutants. Collectively, these findings highlight the redundant and distinct roles of a secreted protein and a CWAP in biofilm formation and pathogenicity of S. aureus and may inform new strategies to control staphylococcal biofilm infections.