Post-procedural Bacillus cereus septic arthritis in a patient with systemic lupus erythematosus.

Barend Mitton,Nontombi Mbelle,Mohamed Said,Wesley Van Hougenhouck-Tulleken,Roxanne Rule

doi:10.4102/ajlm.v9i1.1119

Abstract

IntroductionBacillus species are often considered as contaminants when cultured from clinical samples. Bacillus cereus may be a pathogen in certain circumstances and is known to cause musculoskeletal infections. This report aims to educate clinicians and clinical microbiology laboratories on B. cereus musculoskeletal infections and to heighten awareness that Bacillus species should not always be dismissed as contaminants.Case presentationWe report the case of a patient who presented to a tertiary hospital in Pretoria, South Africa, in November 2018 with B. cereus septic arthritis and underlying systemic lupus erythematosus (SLE). The isolate would otherwise have been dismissed as a contaminant had it not been for the crucial interaction between the laboratory and the treating clinicians. To our knowledge, this is the first case report of septic arthritis caused by B. cereus in an SLE patient where the organism was cultured from the joint specimen. Identification of the organism was performed using matrix-assisted laser desorption/ionisation mass spectrometry.Management and outcomeDefinitive treatment was with intravenous vancomycin, continued for four weeks, in addition to arthroscopy and management of the underlying SLE. The patient had a good clinical outcome and regained full mobility.ConclusionMusculoskeletal infections, specifically septic arthritis caused by B. cereus, are exceedingly rare infections. Immune suppression, trauma, prosthetic implants and invasive procedures are important risk factors for B. cereus musculoskeletal infections. Close collaboration with a multi-disciplinary team approach will effect the best outcome for complicated patients with B. cereus infections.

Highlights

Bacillus species are often considered as contaminants when cultured from clinical samples
We found 56 cases reported over 25 years, highlighting the rarity of B. cereus musculoskeletal infections and emphasising the difficulty in making a definitive diagnosis
Bacillus species are often regarded as contaminants and receive little attention from the medical community

Summary

Introduction

Bacillus species are often considered as contaminants when cultured from clinical samples. The isolate would otherwise have been dismissed as a contaminant had it not been for the crucial interaction between the laboratory and the treating clinicians To our knowledge, this is the first case report of septic arthritis caused by B. cereus in an SLE patient where the organism was cultured from the joint specimen. As the vast majority of Bacillus species are non-pathogenic and ubiquitous in the environment, many clinical microbiologists and clinicians dismiss Bacillus species cultured from clinical specimens as contaminants This results in a missed diagnosis and inappropriate clinical decision-making. This report aims to educate healthcare workers on Bacillus cereus joint infections and further endeavours to assist healthcare practitioners in distinguishing when this organism should be dismissed as a contaminant and when it should be considered as a pathogen

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