# Treatment failure and associated risk factors for periprosthetic-joint infections caused by streptococci versus other etiologies: a single-center retrospective cohort study

## TL;DR

This study found that streptococcal joint infections have similar treatment failure rates as other infections, but certain types like Streptococcus dysgalactiae and specific treatments like DAIR are linked to higher failure risks.

## Contribution

Identified specific risk factors for treatment failure in streptococcal periprosthetic-joint infections compared to other pathogens.

## Key findings

- Streptococcal periprosthetic-joint infections had a 23% treatment failure rate, similar to other pathogens (21%).
- Streptococcus dysgalactiae and DAIR treatment were significantly associated with higher failure rates in streptococcal infections.
- Streptococcal etiology alone was not significantly linked to treatment failure.

## Abstract

There is no consensus on the antibiotic course or type of surgical treatment in streptococcal periprosthetic-joint infections (PJIs). We aimed to compare the treatment failure rate at 2 years of PJIs caused by streptococci to PJIs caused by other pathogens and identify factors associated with failure.

It was a single-center retrospective cohort study conducted between 2009 and 2019. We included all patients aged ≥ 18 years undergoing treatment for hip or knee PJI with a 2-year follow-up. We analyzed the treatment failure rate at 2 years of streptococcal PJIs versus PJIs caused by other pathogens with failure defined as a non-successful treatment using the Delphi-based international multidisciplinary consensus of success. We also analyzed factors associated with failure including streptococcal etiology and type of treatment.

We included 404 patients; 62 (15%) had a streptococcal PJI, of which 14 (23%) exhibited treatment failure at 2 years. The treatment failure rate was similar to that for PJIs caused by other pathogens (21%, 71/342) (P = 0.78). Streptococci were not associated with failure (OR = 1.55, 95% CI 0.62–3.89, P = 0.35). However, Streptococcus dysgalactiae (OR = 9.45, 95% CI 1.37–65.46, P = 0.02) and debridement, antibiotics and implant retention (DAIR) (OR = 9.31, 95% CI 1.80–48.20, P = 0.008) were associated with failure among patients with a streptococcal PJI.

The treatment failure rate of streptococcal PJIs was similar to that for PJIs caused by other pathogens. However, Streptococcus dysgalactiae and DAIR were factors associated with failure among patients with a streptococcal PJI. Our results suggest that streptococcal PJIs, especially Streptococcus dysgalactiae PJIs, should be surgically treated more aggressively with an implant exchange.