Listeria monocytogenes is a gram positive bacterium that causes listeriosis. It is one of the six species of the Listeria genus.
Listeriosis can manifest itself as sepsis, meningitis, encephalitis, intrauterine infections and spontaneous abortions in pregnant women. The onsets of these diseases are usually preceded by persistent fever or gastrointestinal symptoms such as nausea, vomiting and diarrhea.
Listeria monocytogenes is more prone to affect target populations such as pregnant women, newborn infants, immunocompromised individuals on corticosteroids, patients with cancer and other chronic diseases and the elderly. Normally, healthy people can also be infected by Listeria monocytogenes causing minimal gastrointestinal symptoms.
Reservoirs of Listeria monocytogenes are present in the environment, human and animal populations. Transmission of the disease causing bacteria can occur through:
The incubation period for listeriosis is variable and ranges from 3 to 70 days, with the median incubation period being three weeks.
The best method to diagnose a Listeria infection is to isolate the bacteria from body fluids such as Cerebrospinal fluid, blood, gastric secretions among others.
A full course of antibiotic treatment with either penicillin or ampicillin with aminogycosides is a good treatment plan. In penicillin resistant individuals, a third generation cephalosporins or Trimethoprin-Sulfamethoxazole combination is usually prescribed.