Guest posting: Dr Jonathan Ash, Infectious Diseases Registrar, John Hunter Hospital, Newcastle, NSW. 

A recent single centre retrospective case series from Switzerland examined the clinical characteristics, microbiology and treatment of 97 patients with small native joint septic arthritis. The paper highlights significant differences in the pathogenesis of small joint septic arthritis compared to large joints, and shows that rapid de-escalation from intravenous to oral antibiotics in this group can be done safely, negating the need for prolonged hospital admissions or outpatient intravenous antibiotic programs.

The patients included had established septic arthritis in either the wrist or small joints of the hand, based on operative and microbiological findings and exclusion of alternative diagnoses. Baseline demographics showed a comparatively young patient group, with median age of 52 years, of which 52% had no significant co-morbidities. The cause of infection was exogenous in 89% of cases, mostly due to trauma (65%) and animal bites (20%), with only 11% resulting from haematogenous spread,  in stark contrast to large joint infections.

With respect to microbiology, rates of Staphylococcus aureus infection were similar to that in large joints (38%), however Gram negative organisms were slightly more common (20%). Interestingly, the administration of empiric antibiotics prior to biopsy samples did not have a significant impact on whether a positive culture was obtained.

The most important aspect of this paper was in respect to antibiotic treatment which differed markedly to usual practice for large joint septic arthritis. The transition from IV to oral antibiotics occurred within 3-5 days in the majority of cases, with a mean total duration of antibiotics of 14 days (IQR 12-28 days), where,  with a median 2.3 month follow-up, infection resolution was 100%!  84% of isolated organisms were susceptible to amoxicillin+clavulanate, of significance given current piperacillin+tazobactam shortages.

Reference

Meier R, Wirth T, Hahn F, Vögelin E, Sendi P. Pyogenic Arthritis of the Fingers and the Wrist: Can We Shorten Antimicrobial Treatment Duration? Open Forum Infectious Diseases. 2017;4(2).

Image credit: http://www.gponline.com/clinical-review-septic-arthritis/article/1022220