Escherichia coli in septic arthritis: prevalence and antibiotics susceptibility patterns.

Background and objectives: Septic arthritis (SA) is an orthopedic emergency mainly caused by bacteria. SA due to Escherichia coli (E. coli) is rare with a poor prognosis. This study aimed to assess the occurrence and antibiotic resistance patterns of E. coli in SA patients in Quetta, Balochistan, Pakistan.

Materials and methods: A cross-sectional study was conducted from March 2021 to December 2023. 220 samples were collected from SA patients from tertiary care hospitals. Joint aspirates (2ml) and blood (5ml) were analyzed for microbial and hematological examination.

Results: There were 5.45% samples positive, and 94.5% negative for E. coli. SA due to E. coli was more common in male (6.2%) than female (4.6%) patients with the knee being the most affected joint (6.3%). E. coli was more common in patients aged 41-60 years (7.7%), lower socioeconomic (6.9%), and illiterate (8.6%) patients. Suspected patients showed a significant increase in the levels of white blood cells (WBC), C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR), notably, these levels were further elevated in E. coli-positive patients. The polymerase chain reaction (PCR) based identification of E. coli showed clear bands of 204bp of the 16S rRNA gene. Sequence analysis using the Basic Local Alignment Search Tool found high similarity with pathogenic E. coli from Egypt and China. The identified E. coli strain showed significant resistance to common antibiotics: amoxicillin, amoxicillin-clavulanate, ceftriaxone, sulfamethoxazole/trimethoprim, gentamicin, tetracycline, and erythromycin.

Conclusion: Antibiotic resistance in E. coli from SA patients suggests the need for accurate antibiotic selection to ensure prompt treatment.