Risk factors and outcomes of emerging Listeria monocytogenes infection in Pakistan: Insights from a tertiary care hospital

BACKGROUND: Listeria monocytogenes is a Gram-positive rod responsible for listeriosis. It has emerged as a significant foodborne pathogen and has been implicated in numerous outbreaks worldwide often present with bacteremia and may progress to severe manifestations such as meningoencephalitis, particularly in immunocompromised individuals and the elderly. Maternofetal infection is associated with worse pregnancy outcomes. The objective of this study is to assess the risk factors, clinical features, and outcomes of patients admitted with Listeria monocytogenes infection at a tertiary care Centre in Karachi, Pakistan. METHODS: A retrospective study was conducted over 7 years and included all patients with culture-proven listeriosis. Comorbid conditions, clinical presentation, treatment, and outcomes were recorded and analyzed. RESULTS: A total of 63 patients diagnosed with Listeria monocytogenes infection were included in the study. There was a female predominance (n = 44, 69.8%), with a median age of 53(32.0, 67.0) years. Diabetes mellitus was the most common comorbidity (n = 27, 42.9%). Among high-risk groups, 14 (22.6%) patients were pregnant, 10 (15.9%) were on immunosuppressive therapy, and another 10 (15.9%) were classified as elderly. The predominant presenting symptoms included fever (n = 47, 74.6%) and central nervous system involvement (n = 28, 44.4%), mainly meningoencephalitis. All patients received antibiotic therapy with either ampicillin or meropenem for a mean duration of 16.7 ± 8.4 days. The overall mortality rate was11.1%.(n = 7). CONCLUSION: Listeriosis was observed not only in the elderly but also in middle-aged individuals with underlying risk factors, as well as in pregnant women.Improved environmental hygeine, early diagnosis, and timely treatment are essential to improving outcomes, particularly in pregnancy-related cases. Public education, healthcare provider training, and community-level preventive strategies are critical for effective management and control of listeriosis.