Prosthetic joint infection (PJI) is an uncommon but serious complication after total hip and total knee arthroplasty. While two-stage revision is often considered the gold standard, DAIR (debridement, antibiotics, and implant retention) is used as a less morbid option for selected patients. The authors aimed to determine whether microbiologic etiology influences DAIR success, with particular emphasis on fungal, antibiotic-resistant, and culture-negative PJIs, and to identify organism-specific predictors that could inform treatment strategy.
This was a single-center retrospective chart review approved by the institutional review board (IRB #2021H0358). The cohort included patients treated for PJI after total hip arthroplasty (THA) or total knee arthroplasty (TKA) between 01/01/2016 and 06/20/2025 who underwent DAIR as the primary procedure for infection. Patients were identified using ICD-10 diagnosis codes and then screened to meet a modified Musculoskeletal Infection Society (MSIS) definition for PJI. Cases were excluded if the primary procedure for PJI was incision and debridement (I&D), single-stage revision, explant only, or explant and spacer. Index arthroplasty for primary malignancy or bone sarcoma were also excluded.
Culture results were categorized by status (culture-positive vs culture-negative), fungal versus non-fungal, polymicrobial status, antibiotic-resistant status, and gram-negative/gram-positive classification. Institutional laboratory practices included holding aerobic and anaerobic cultures for at least 14 days, fungal cultures for 28 days, and acid-fast cultures for 42 days. The Microbiology Department flagged potential contaminants; contaminated specimens were not considered culture-positive. Antimicrobial regimens were determined by the treating surgeon and infectious disease team; culture-negative cases received, at minimum, broad-spectrum coverage for gram-positive and gram-negative organisms.
Data abstracted into the institutional PJI database included demographics (age, sex), laterality, infection chronicity, procedure type (THA or TKA), body mass index (BMI), smoking status, medical comorbidities, MSIS laboratory elements available at the center, and culture data as described above. Outcome success was defined according to Delphi consensus as eradication of infection without recurrence or the need for further surgical intervention for infection. Charlson Comorbidity Index (CCI) was used to quantify comorbidity burden for subgroup analyses.
Logistic regression analyses were used to evaluate associations between treatment success and microbiologic characteristics. Additional regression assessed relationships between fungal PJI and patient comorbidities. Odds ratios (ORs), 95% confidence intervals (CIs), and P values were reported for associations of interest.
The study evaluated 173 PJIs treated with DAIR. Overall, infection eradication was achieved in 66.5% of cases. Key organism-specific findings included:
Fungal pathogens were significantly associated with DAIR failure compared with non-fungal organisms (OR 0.06, 95% CI 0.011–0.31, P = 0.001).
Culture-negative infections were more likely to achieve eradication than culture-positive infections (OR 3.91, 95% CI 1.43–10.69, P = 0.008).
Antibiotic-resistant organisms and gram-positive pathogens were associated with lower success rates; the report indicates these associations without supplying additional numerical breakdowns beyond those cited for fungal and culture-negative groups.
Polymicrobial infections did not show a significant difference in eradication success compared with single-organism infections (P = 0.92).
Fungal PJIs constituted 8% of the cohort. Patients with fungal infection demonstrated a higher comorbidity burden, with a median Charlson Comorbidity Index of 4 versus 2 for non-fungal cases (P = 0.0496). The strong association between fungal etiology and DAIR failure supports a distinct risk profile for these patients.
Findings indicate that microbiologic etiology meaningfully influences DAIR outcomes. The markedly lower likelihood of eradication when fungal organisms are involved, and the poorer outcomes associated with antibiotic-resistant and gram-positive pathogens, suggest pathogen-informed decision-making is important when selecting candidates for DAIR versus alternative surgical strategies such as implant exchange or staged revision. Conversely, culture-negative PJIs in this cohort were more likely to be successfully treated with DAIR.
These observations support the practice of incorporating microbiologic risk stratification into preoperative planning and postoperative surveillance. The study also underscores that antimicrobial choices were individualized by treating teams, and that institutional laboratory practices (including extended fungal culture holds) may affect pathogen detection and classification.
This analysis is limited by its retrospective, single-center design and reliance on a modified MSIS definition (synovial CRP was not available and therefore omitted). The study reports outcomes for a specific institutional population with defined culture-hold practices; these factors may limit generalizability. The authors noted that the underlying database contains potentially identifiable information and is restricted by institutional policies; data access requests were directed to a named contact in the original report. Funding and competing interest statements indicated no specific funding and no declared competing interests.
In this single-center retrospective cohort of 173 PJIs treated with DAIR, overall eradication occurred in two-thirds of cases. Fungal organisms and antibiotic-resistant pathogens were associated with significantly lower rates of infection eradication, while culture-negative infections had higher odds of successful DAIR. These results support pathogen-specific risk stratification when considering DAIR and suggest that alternative surgical management or intensified follow-up may be warranted for high-risk organisms.