An immunocompetent patient presenting with severe septic arthritis due to Ralstonia pickettii identified by molecular-based assays: a case report

INTRODUCTION: Ralstonia pickettii is an infrequent pathogen of invasive infections in healthy individuals. The microorganism is supposed to be of relatively low virulence, but can cause infections, mainly of the respiratory tract, in immunocompromised and cystic fibrosis patients. Ralstonia pickettii has also been associated with hospital outbreaks related to contamination of products used for medical care and laboratory diagnosis. CASE PRESENTATION: We report here a case of septic arthritis due to Ralstonia pickettii in a female diabetic patient. The microorganism was identified from the synovial fluid by molecular-based methods, while the conventional synovial and blood cultures proved to be negative. The patient was treated by intravenous ceftazidime with complete remission of her symptoms; she was discharged 3 weeks after admission in a very good health. At follow-up examination 3 weeks later, she was still in good health condition without any sign of arthritis of the right knee and afebrile. CONCLUSION: In culture negative serious bacterial infections, as septic arthritis, the use of molecular-based techniques might be of outmost importance as additional and rapid diagnostic tools for the identification of the causative agent allowing a prompt and appropriate antimicrobial therapy and a favourable outcome.