What is Microbiology - Listeriosis

​Listeriosis

Listeriosis is a form of infection which is caused by listeria monocytogenes. 

Listeriosis may appear to be asymptomatic mostly in immuno competent adult. Fetal listeriosis may lead to stillborn birth and spontaneous abortion. Fetal listeriosis may lead to pneumonia, meningitis and granulomatosis infantiseptica ( septicemia). 

The common mode of transmission is via contamination of the food such as contaminated cheese, milk, meat, seafood and poultry.  Person to person spread such as nosocomial transmission by hospital staff, infection of the uterus and colonization of the birth canal may also lead to transmission of listeria monocytogenes infection. 

Listeria monocytogenes may invade the endothelial cells of the placenta in a pregnant women which lead to transplacental spread of  listeria monocytogenes infection. 

In immunocompromised individual ( organ transplant recipient or chemotherapy ) adult bacterial meningitis may occur due to infection by listeria monocytogenes.

Listeria monocytogenes is a gram positive rod which able to survive ( intracellular growth) at low temperature. Contamination of the food still occur if the food is stored at the refrigerator. 

Listeria monocytogenes has two virulence factors which are listeriolysin O and internalin that facilitate the invasion of the host cell. Listeriolysin O will allow listeria monocytogenes to escape form the endosome. Listeriolysin O is a pore forming toxin. Listeria monocytogenes has a tumbling motility.

Internalin will promote endocytosis by binding to the host cell.