From the Research
The recommended surveillance duration for asymptomatic patients potentially exposed to Listeria monocytogenes is typically 70 days from the time of exposure. During this period, patients should be monitored for symptoms such as fever, muscle aches, nausea, diarrhea, headache, stiff neck, confusion, or balance problems. No prophylactic antibiotics are recommended for asymptomatic exposed individuals. If symptoms develop, immediate medical evaluation is warranted, including blood cultures and possibly cerebrospinal fluid analysis, followed by appropriate antibiotic therapy (typically ampicillin or a combination of ampicillin and gentamicin for confirmed infections) 1. This extended surveillance period is necessary because Listeria has one of the longest incubation periods among foodborne pathogens, ranging from 3 to 70 days, with a median of 21 days. The bacterium's ability to cross the blood-brain barrier and placental barrier makes it particularly dangerous for pregnant women, newborns, elderly individuals, and immunocompromised patients, who should be monitored more closely during this period.
Some key points to consider during surveillance include:
- Monitoring for symptoms and immediate medical evaluation if they develop
- No prophylactic antibiotics for asymptomatic individuals
- Antibiotic therapy with ampicillin or a combination of ampicillin and gentamicin for confirmed infections
- Close monitoring of high-risk groups, including pregnant women, newborns, elderly individuals, and immunocompromised patients
It's essential to note that the surveillance duration is based on the longest incubation period reported, which is up to 70 days, as mentioned in the study published in 2022 1. This study highlights the importance of prolonged surveillance to ensure the detection of potential infections, particularly in high-risk populations.
In terms of antibiotic resistance, studies have shown that Listeria monocytogenes strains can exhibit resistance to various antibiotics, including penicillin and ampicillin 2, 3. However, the most recent and highest-quality study should guide treatment decisions, and in this case, ampicillin or a combination of ampicillin and gentamicin remains the recommended treatment for confirmed infections.
Overall, the recommended surveillance duration and treatment approach prioritize minimizing morbidity, mortality, and improving quality of life for individuals potentially exposed to Listeria monocytogenes.