# Prospective Comparative Analysis of Simultaneous Microbiological Assessment in Septic Revision Arthroplasty: Can We Rely on Standard Diagnostics?

## TL;DR

This study compares microbiological results from two labs in septic joint revision surgery, finding significant inconsistencies that could affect treatment decisions.

## Contribution

The study reveals inconsistencies in pathogen detection between accredited labs, highlighting the need for standardized protocols in diagnosing joint infections.

## Key findings

- 62.5% of patients showed consistent results between the two laboratories.
- 37.5% of patients had diverging results, with 12 cases showing a partly different pathogen spectrum.
- Discrepancies led to changes in antibiotic treatment for 12.5% of patients.

## Abstract

Background: Microbial analyses of tissue samples are of paramount importance for diagnostic and therapeutic purposes in the course of septic revision arthroplasty. Isolation and identification of the causative pathogens pave the way for successful treatment of periprosthetic joint infections, which necessitates a reliable microbiological workup. It is unknown if there are inconsistencies in pathogen detection and differentiation between accredited laboratories in the context of septic revision arthroplasty. Methods: Tissue samples of forty consecutive patients undergoing septic total hip and knee revision surgery were sent to two different accredited and certified laboratories and tested for pathogen growth and bacterial differentiation. Results: Each institution analyzed 200 specimens. Twenty-five patients (62.5%) showed consistent results between laboratories. Diverging results were observed in 15 of 40 patients (37.5%). Of these, three individuals showed pathogen growth in only one laboratory. In 12 patients with discrepant results, laboratory analyses revealed a partly different pathogen spectrum. With regard to clinical impact and infection eradication, the respective differences implicated a therapeutic response by a change of the administered postoperative antibiotic treatment in five (12.5%) of the patients. The kappa correlation coefficient indicated a slight value in terms of data consistency between institutions (k = 0.227, p = 0.151). Conclusions: The majority of evaluated samples show comparable results with regard to microbiological evaluation. Nevertheless, a substantial number of specimens were classified differently. The observed discrepancies pose a challenge for postoperative decision-making. Against this background, standardized microbiological protocols remain mandatory for a conclusive clinical implication to eradicate PJI.