392. Epidemiology and Treatment Outcome of Gram-Negative Polymicrobial, Gram-Positive Polymicrobial and Mixed Polymicrobial Prosthetic Joint Infection

BACKGROUND: Polymicrobial prosthetic joint infections (PMPJIs) are rare but treatment is usually challenging. Published studies described the PMPJIs without differentiating the component pathogens. We assessed clinical features and treatment outcome among Gram-negative polymicrobial (GNPM), Gram-positive polymicrobial (GPPM) and mixed polymicrobial (MPM) PJIs. METHODS: A retrospective cohort was studied at three Ascension hospitals in Detroit from January 2012 to December 2018. Cases were identified using the International Classification of Diseases, 9th and 10th Revision code specific for PJIs. Patient’s electronic medical records were reviewed. RESULTS: 38 patients with PMPJI with a mean age of 67 years. were identified. 71% patients were female and caucasians. Nineteen (50%) patients had MPM, 16 (42%) had GPPM and 3 had GNPM. Among MPM PJIs, 14 (74%) involved hips, 4 (21%) knee and 1 (5%) ankle joint. Among GPPM PJIs, 7 (44%) involved hips, 8 (50%) knee and 1 (6%) shoulder joints. Among GNPM PJIs, 1 (33%) involved hip and 2 (67%) involved knee joints. 4 (21%), 1 (6%), and 1 (33%) patients had diabetes among MPM, GPPM and GNPM, respectively. Symptom onset of less than a week was noted in 13 (68%), 5 (31%), 3(100%) and of more than 3 weeks in 3 (16%), 7 (43%) and in 0 among MPM, GPPM and GNPM, respectively. 18 (95%), 12 (75%) and 2 (67%) patients presented with pain; 16 (84%), 6 (38%) and 3 (100%) patients had drainage among MPM, GPPM and GNPM, respectively. Among MPM PJIs, 12 (63%) underwent debridement, antibiotics and implant retention (DAIR), 2 (11%) for two stage exchange, 4 (21%) for chronic suppressive therapy and 1 (5%) had an amputation. 6 (58%) were readmitted within 6 months; 3 (50%) required prosthesis removal, 1 (4%) each died, was made hospice and was lost to follow-up. Among GPPM PJIs, 12 (75%) underwent DAIR and 4 (25%) went for two stage exchange. 9 (69%) patients among GPPM PJIs were readmitted in 6 months and 3 (50%) required prosthesis removal. All 3 of GNPM PJIs underwent DAIR and none were readmitted in 6 months. CONCLUSION: Pain and drainage were common presenting symptoms. All GNPM PJIs presented within 1 week of symptoms and were treated successfully with DAIR. MPM and GPPM PJIs had high readmission rates and 6/26 (23%) managed with DAIR required prosthesis removal. DISCLOSURES: All authors: No reported disclosures.