# A Novel Case of Citrobacter koseri Septic Arthritis in a Native Knee Joint

## TL;DR

This paper reports the first case of Citrobacter koseri septic arthritis in a native knee joint, highlighting its rare occurrence and treatment options.

## Contribution

The first documented case of C. koseri septic arthritis in a native knee caused by hematogenous spread without prior trauma.

## Key findings

- Citrobacter koseri is a rare cause of septic arthritis in native knee joints.
- All identified cases of C. koseri musculoskeletal infections resolved with antibiotic or surgical treatment.
- C. koseri septic arthritis can be effectively treated with newer beta-lactams and cephalosporins.

## Abstract

Citrobacter koseri is a rare cause of septic arthritis in a native knee joint. We present the first recorded case of C. koseri septic arthritis in the native knee from a hematogenous spread resulting from a gastrointestinal illness, along with a review of the literature. A search of PubMed, Embase, OVID, and Google Scholar was conducted. Fifteen cases of musculoskeletal infection were identified, and of these, only six cases involved a septic joint and one case involved a septic knee. None of the recorded adult cases presented hematogenously without prior trauma. All of the cases achieved resolution after either antibiotic treatment alone or in conjunction with surgical treatment. Citrobacter koseri is not a rare cause of infection in general. However, it is not a common cause of septic arthritis, and this may complicate the treatment course as it can be overlooked as a cause of infection. It is essential to obtain a thorough history and a broad differential diagnosis when evaluating septic arthritis as although it may be difficult to identify the infection, C. koseri septic arthritis can be effectively treated with surgery as well as newer generation beta-lactams and cephalosporin antibiotic therapy.