Listeria monocytogenes outbreak – serendipity or emerging threat?

Document Type





Background: Listeria monocytogenes is a facultative, catalase positive, anaerobic, gram-positive bacillus resulting in an infection known as listeriosis. It is one of the many neglected zoonotic diseases. Developing countries with low socio-economic status rely on animals especially cattle for their economy, have higher incidence rates of this disease. The infection spreads via bloodstream causing bacteremia and later may cause serious complications like meningitis. The disease is more common in immune compromised individuals including pregnant females, extremes of ages and those on chemotherapy, and steroids. Listeriosis is markedly under reported hence the true number of affected cases is not known.
Material and Methods: We are describing six cases of Listeria monocytogenes infection in a tertiary care hospital in Karachi, Pakistan. Blood cultures and body fluid sample - cerebrospinal fluid were collected from these patients and tested for infection.
Results: Out of these six cases, five patients had active bacteremia resulting in positive blood cultures. Two of these five patients had positive cerebrospinal fluid (CSF) for Listeria monocytogenes infection as well. One patient only had CSF polymerase chain reaction (PCR) positive without bacteremia.
Conclusions: Few cases of human Listeria monocytogenes infection are reported from Pakistan. In Aga khan University hospital, we identified six cases of Listeria monocytogenes infection in two weeks. We actively managed and studied the clinical course in affected patients. The risk factors were identified and patients were called for follow up. This study emphasizes on the development of prompt measures to prevent future incidences like these by identifying risk factors and disease process.


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Publication (Name of Journal)

Infectious diseases journal of Pakistan