Abstract
Background
Listeria monocytogenes (Lm) is a foodborne pathogen that can lead to severe pregnancy outcomes. This study reports the clinical and genomic characteristics of a Listeria-mediated stillbirth identified through the Child Health and Mortality Prevention Surveillance (CHAMPS) project in Bangladesh. The Lm-BD-CHAMPS-01 isolate was recovered from the blood and cerebrospinal fluid (CSF) of a male stillborn baby. Maternal history, clinical, and demographic data were collected by the CHAMPS surveillance platform. An expert panel evaluated all reports to determine the role of Lm infection in the causal chain of stillbirth. Genomic characterization included multilocus sequence typing (MLST), core genome MLST (cgMLST), serotyping, and the presence or absence of virulence and stress adaptation genes. Genetic divergence and phylogenetic analyses were conducted to determine the relationship with other reported isolates globally.
Results
The isolate Lm-BD-CHAMPS-01 was identified as a novel cgMLST CT11424. It belonged to ST 308, Serotype 4b, Clonal Complex 1, and Phylogenetic Lineage 1. Key Lm virulence genes facilitating the crossing of the placental barrier, including full-length inlA, LIPI-1, and LIPI-3, were detected. The isolate was closely related to clinical Lm isolates, as determined by Grapetree based on cgMLST. SNP-based phylogenetic analysis found Lm-BD-CHAMPS-01 to be the most distant from other CC1 isolates in the database. Possible sources of infection included the consumption of contaminated raw vegetables or exposure to pigeons.
Conclusions
The virulence profile of the first genome sequence of clinical Lm from Bangladesh, which also caused stillbirth, underscores the understudied nature of this pathogen in the region. Rural healthcare professionals should be aware of Lm infection risks during pregnancy. Pregnant women should be counseled on the dangers of consuming potentially contaminated raw food and exposure to animals or birds to prevent adverse pregnancy outcomes due to Lm infection.