Background/Purpose: In recent years, joint replacement surgery (JRS) has become increasingly common. Prosthetic joint septic arthritis (PJSA) may complicate JRS in up to 1% of cases. As is true for other types of infections (e.g. cellulitis, pneumonia), the microbiologic causes of PJSA may change over time. Early, effective therapy of PJSA may be enhanced by improving our knowledge on the major causes of PJSA. In this study we aimed to determine the trends in the organisms associated with PJSA.

Methods: We conducted a retrospective study including all patients 18 and older with surgically-treated, culture-positive PJSA admitted to a single tertiary medical center in Boston between the years of 1997-2015. We excluded cases of culture negative SA, native joint SA, osteomyelitis and septic bursitis. Patients with prosthetic joint arthritis were considered culture-positive if pathogenic bacteria were isolated from synovial fluid, blood cultures or synovial biopsy.

Results:

We identified 190 patients with culture- positive PJSA. The most commonly identified organisms over the study period were: Methicillin sensitive Staphylococcus aureus (MSSA) (34.2%), coagulase negative Staphylococci (CoNS) (18.9%), methicillin resistant Staphylococcus aureus (MRSA) (13.2%) and group B Streptoccocus (GBS) (11.6%). When our cohort of patients was divided into 5 years intervals, a significant change in the rates of MRSA related PJSA was observed: 7.7% in 1997-2002, 28.9% in 2003-2008, 9.7% in 2009-2014, p value = 0.005.

Over the study period 12.6% of the patients presented with early PJSA (JRS<=42 days), 26.8% with delayed PJSA (365>JRS>42 days) and 54.2% with late PJSA (JRS>365 days). A trend toward a significant increase in GBS related late PJSA was observed (early GBS related PJSA= 4.2% delayed GBS related PJSA =5.9% late GBS related PJSA= 17.5%, p value=.060). Enterococcus, Pseudomonas aeruginosa and Streptococci Viridins were not isolated in the early PJSA group.

Conclusion: Similar to other studies we showed that MSSA, CoNS and MRSA are the top three causes of PJSA. The novel observations of our study include the falling incidence of MRSA in recent years, the higher rates of GBS in late PJSA and the absence of Enterococci and Pseudomona Aeruginosa in early PJSA.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/organisms-associated-with-prosthetic-joint-septic-arthritis-over-the-past-two-decades-data-from-a-single-tertiary-medical-center-located-in-the-northeastern-united-states/