74 - Septic arthritis and Lyme arthritis Comparisons in a “Lyme-transitional” Region

Poster Number: 74
Publication Number: 74.1287

Background: Lyme disease (LD) is the most commonly reported vector borne disease in the United States. Recently we have seen an exponential increase Lyme disease rates in Ohio. These changes are possibly secondary to the expanding range of blacklegged tick populations as a result of climate changes. As we started to see changes in LD rates, we have observed several children admitted with Lyme arthritis (LA) manifestations who underwent surgical procedures in addition to diagnostic joint fluid aspirations.

Objective: We wanted to identify differences between septic arthritis (SA) and Lyme arthritis patients in a region with increasing LD rates, and then to compare clinical, laboratory manifestations and outcomes of LA with and without surgical intervention.

Design/Methods: This study was done as part of a quality improvement project at our Children’s Hospital. All patients with concerns for an infectious arthritis are admitted to our infectious diseases unit. The study period was between January 1, 2020, to August 1, 2023. EMRs were reviewed for demographic information, clinical presentation, length of stay (LOS), antibiotics used, diagnostic tests, surgeries/procedures, follow up visits by infectious diseases and orthopedic surgery. Only patients with culture and/or PCR proven bacterial arthritis were included in the SA group. Lyme serologies and available synovial PCRs were reviewed. Two-tailed p-values < 0.05 were used to determine significance.

Results: Of the 74 patients, 29 patients were diagnosed with SA, 45 had LA (Table 1). Increase in LA was observed since 2021. LA patients were older with predominantly knee involvement. Fever was more common on admission among SA patients. There was no significant difference in reported pain and swelling of the joints. There was no significant difference between LA and SA patients for admission inflammatory markers, or synovial WBC counts. LA patients undergoing surgical washouts had elevated CRP, synovial WBC counts and delayed Lyme testing in comparison to the others that did not have surgical washouts. 27 (60 %) of LA patients were initially treated with anti-staphylococcal antimicrobial agents and 7 (18%) were discharged home on no or inappropriate antibiotics. Surgical procedures decreased since the second half of 2022.

Conclusion(s): Both LA and SA patients presented with joint effusion, elevated inflammatory markers and elevated synovial WBC counts creating ambiguity. The changes in epidemiology, diagnostic ambiguity and delayed results for diagnostic testing have been associated with possibly unnecessary operative interventions and increased length of stay.