Listeriolysin O antibodies detection in pregnant women: results from an Italian pilot study

Listeriosis is a rare infection affecting primarily pregnant women, the elderly and individuals with a weakened immune system and is caused by the ubiquitous bacterium Listeria monocytogenes. Infection during pregnancy can cause severe consequences especially for the fetus, leading to sepsis, premature delivery, stillbirth and miscarriage.

A pilot observational study has been conducted in order to establish the prevalence of seroconversion of specific antibodies against a peculiar toxin belonging to L. monocytogenes, listeriolysin O (LLO), in a population of pregnant women from Senigallia (Central Italy) and to find correlations between anti-LLO antibodies seropositivity and health and nutritional information. A total of 60 women were screened for anti-LLO antibody positivity and interviewed during their pregnancies. Statistical analyses were performed to evaluate antibody prevalence in serum samples and potential risk factors.

The seroprevalence resulted 18% (95% CI, 8.2 - 27.7%), corresponding to 11 pregnant women. Categorical principal component analysis and hierarchical cluster analysis revealed a significant correlation between anti-LLO positivity and gastrointestinal pain events and vomit, fever and diarrhea episodes, and a possible association with consumption of pre-cooked meal. No significant correlation was observed in women with a previous miscarriage or with miscarriage cases in their families.

Findings from this pilot study will be used to design a wider study focused on the prevalence of Listeria-specific antibodies in pregnant women and could allow to the identification of nutritional and behavioral habits related to Listeria infection which could lead to significant clinical implications.