Public Health England (PHE) has issued guidance on listeriosis for healthcare professionals (HCPs). The guidance comes after Greenyard Frozen UK recalled a number of frozen vegetable products in early July 2018 due to the possible presence of Listeria monocytogenes, a rare cause of food poisoning. Listeria rarely causes invasive infection in healthy individuals and most will either be asymptomatic, and some may experience mild self-limiting diarrhoea and abdominal cramps.
However, some factors may increase the risk for invasive infection, including pregnancy, extremes of age (neonates and >60 years of age), preexisting clinical conditions, and use of immunosuppressive medications. In such individuals, invasive disease may manifest as sepsis, encephalitis, meningitis, which may or may not be preceded by febrile gastroenteritis and carries a mortality rate of 20%-30%.
Fever, severe body ache, headache and febrile gastroenteritis may be suggestive of invasive disease. Blood culture is the most reliable detection method. Cerebrospinal fluid/joint fluid analysis or PCR may alternatively be used for diagnosis. Pregnant women are at a much higher risk for invasive infection. Maternal infections may be asymptomatic or present with nonspecific influenza-like symptoms. However, foetal and neonatal infections are often dangerous and could result in foetal loss, preterm labour, neonatal sepsis, meningitis and death.
Invasive infection must be treated with intravenous antibiotics according to the local hospital antimicrobial policy. First-line antibiotics include amoxicillin with or without gentamicin as per the clinical presentation. Cotrimoxazole (trimethroprim/sulfamethoxazole) is a preferred option in nonpregnant individuals sensitive to penicillin, whereas vancomycin or meropenem are alternatives for pregnant individuals sensitive to penicillin, although caution must be exercised. Chloramphenicol is not recommended due to lower reliability and risk for treatment failures.