# The proportion of chronic periprosthetic joint infection patients with Candida isolates

## TL;DR

This study estimates that Candida fungi are involved in about 5% of joint infections, with higher rates in chronic cases that don't respond to treatment.

## Contribution

The study introduces a novel method to adjust for underreporting biases in fungal joint infection data using imputation techniques.

## Key findings

- Candida involvement in PJI was estimated at 5.1% after adjusting for under-ascertainment biases.
- Chronic refractory PJI cases had a likely Candida incidence exceeding 10%.
- Adjustment methods revealed a wide range of 1.4% to 13.6% for Candida-associated PJI.

## Abstract

Introduction: Fungal periprosthetic joint infection (PJI) has historically been reported in 1 %–2 % of cases, with Candida species accounting for most isolates. However, the true incidence is likely underestimated. Standard aerobic and anaerobic culture techniques have limited sensitivity for detecting fungi, single positive fungal cultures are often excluded or inconsistently classified, culture-negative infections may mask low-burden fungal pathogens, and polymicrobial cultures may obscure the contribution of fungal organisms. The objective of this study was to quantify the burden of potentially unrecognized fungal involvement and provide a more accurate estimate of the incidence of Candida-associated PJI. Methods: Following a systematic literature search, we performed a quantitative sensitivity analysis using imputation with informative missingness odds ratios (IMORs). Reported Candida cases were adjusted for four predefined sources of under-ascertainment: single positive cultures, negative cultures, polymicrobial cultures, and variability in fungal culture sensitivity. Results: 23 studies met inclusion criteria, reporting a total of 28 253 PJI patients, of whom 590 had Candida involvement (2.1 %; range 0.9 %–10.1 %). After imputation for missing data, the estimated proportion of PJI cases involving Candida ranged from 1.4 %–13.6 %, with a mean of 5.1 %. The odds ratios for known risk factors for chronic refractory PJI exceeded 2.0, suggesting the proportion of Candida in this population likely exceeds 10 %. Conclusion: The involvement of Candida in PJI is likely underreported. The adjusted incidence is approximately 5 % across all PJI cases. Among patients with chronic refractory PJI, especially those that have failed multiple surgeries, the incidence of Candida PJI is approximately 10 %. Level of Evidence: Level III.