# Bone and Joint Infections in Tropical Settings: High Prevalence of Gram-Negative Bacilli and Implications for Empirical Therapy

## TL;DR

This study shows that tropical bone and joint infections are often caused by drug-resistant bacteria, suggesting a need for updated antibiotic guidelines in these regions.

## Contribution

The study identifies a high prevalence of Gram-negative bacilli in tropical bone and joint infections and evaluates antibiotic effectiveness in this context.

## Key findings

- Gram-negative bacilli accounted for 41% of isolates in tropical bone and joint infections.
- Cefazolin showed lower in vitro efficacy compared to cefepime and piperacillin-tazobactam for treating these infections.
- Local surveillance systems are recommended to guide empirical antibiotic treatment in tropical settings.

## Abstract

Bone and joint infections (BJIs) are increasingly reported worldwide, but data on their epidemiology remain limited in tropical settings. We aimed to characterize the causative agents of BJIs and their resistance patterns, in order to inform empirical antibiotic in our tropical setting.

This 6-year retrospective study included all adults with a first microbiologically confirmed episode of BJI between January 2019 and December 2024 at the Guadeloupe University Hospital, a tertiary care center in the Caribbean.

A total of 312 patients with BJI were included. Among the 449 isolates recovered, Gram-negative bacilli (GNB) were predominant (41%), including AmpC β-lactamase–producing Enterobacterales (13%, 59/449) and Pseudomonas aeruginosa (9%, 39/449). Methicillin-resistant Staphylococcus aureus accounted for 3% (13/449). At least one GNB was identified in 31% of native septic arthritis (27/88), 33% of spondylodiscitis (9/27), 38% of prosthetic joint infections (27/71), 47% of osteosynthesis-associated infections (48/103), and 52% of osteomyelitis (12/23). Factors independently associated with GNB infection were a history of bite/scratch wound, contact with soil/vegetation and lower limb infection. Cefazolin provided limited likelihood of in vitro adequacy against causal pathogens in native septic arthritis episodes (74%, as compared to 92% for both cefepime and piperacillin-tazobactam). Lower rates were observed in cases of osteosynthesis-associated and prosthetic joint infections (48%–68%, as compared to 62%–75% for third-generation cephalosporins, 79%–80% for cefepime and 80%–86% for piperacillin–tazobactam).

Our findings highlight the prominent role of GNBs in tropical BJI and support the implementation of local surveillance systems to guide empirical treatment strategies.