A rare case of Salmonella Infantis urinary tract infection in a high-risk elderly patient

Abstract

Salmonella spp. are predominantly recognized as enteric pathogens, while urinary tract infection represents a rare extraintestinal manifestation, often indicating underlying host vulnerability. This report describes a case of urinary tract infection in a 63-year-old male with multiple predisposing factors, including chronic hepatitis B and C infection, prolonged immobilization, a grade IV sacral pressure injury, and prior prolonged hospitalization. The patient presented with fever, lethargy, and persistent urinary symptoms. Although initial urine microscopy showed no visible bacteria, subsequent urine culture yielded Salmonella spp. Further identification of the isolate was performed using the API® (Analytical Profile Index) system, which identified it as S. infantis. Simultaneously, blood cultures isolated ESBL-producing Escherichia coli, suggesting a complex systemic co-infection. Antimicrobial susceptibility testing revealed that S. infantis was resistant to ceftriaxone but susceptible to fluoroquinolones. Initial empirical therapy with IV Ceftriaxone was unsuccessful; however, targeted therapy with IV Ciprofloxacin 400mg BD for 14 days led to clinical stabilization within 48 hours. This case highlights the importance of considering atypical pathogens such as S, infantis in urinary tract infections, particularly in high-risk and immunocompromised patients. Early microbiological identification and susceptibility testing are essential for appropriate management and improved clinical outcomes. In conclusion, accurate microbiological diagnosis plays a critical role in the management of unusual urinary tract infections, especially in complex patients with multiple comorbidities.