1363. Most Psoas Abscesses are Pyogenic; not Tuberculous: Experience from South India

Abstract

Abstract Background It is a common belief that psoas abscess in patients from developing countries like India are mostly tubercular in origin. However, most of the diagnosis of a tubercular psoas abscess are based on radiological features and are not confirmed microbiologically. It is possible that many cases of pyogenic psoas abscesses are misdiagnosed as tubercular due to lack of good quality microbiology lab facilities in developing nations. We studied the microbiology of psoas abscess in patients admitted to KIMSHealth, a tertiary care hospital in Kerala, South India. Methods Clinical details of patients with a diagnosis of psoas abscess over a 6-year period (2015 – 2020) were retrieved from electronic medical records. Microbiological investigations done included bacterial culture of the pus, fungal culture, mycobacterial culture, cartridge based nucleic acid amplification test for Mycobacterium tuberculosis and blood cultures. Results 21 patients who had complete clinical details were included. 15 of them were males and the median age was 58 years. Diabetes mellitus was the most common comorbidity (52%). Fever (61.9%) and back pain (52.4%) were the most common symptoms. The abscess was left sided in 11 patients, right sided in 7 and bilateral in 3. Vertebral involvement was present in 9 patients while hip joint was involved in 3 patients. A microbiological diagnosis was made in 14 patients (66%). Most commonly isolated organism was Staphylococcus aureus (8 patients,MSSA:6, MRSA:2) followed by E.coli (3)and Klebsiella pneumoniae (2). Blood cultures were positive in 5 patients. Anti-tuberculous therapy was started in only one patient, which was based on characteristic histopathology and negative bacterial cultures. Rest of the culture negative cases were also treated as pyogenic abscesses with antibiotics. Surgical drainage was done for 7 patients and pig tail drainage for 3 patients, while percutaneous aspiration was done for 9 patients. All 19 patients who followed up had clinical resolution, while two were lost to follow-up. Conclusion Contrary to what is believed, we observed that most psoas abscesses are pyogenic in origin. Our observations reiterates diligent microbiological investigations in all cases of psoas abscess to avoid empiric anti-tuberculous therapy. Disclosures All Authors: No reported disclosures