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Pregnancy-related listeriosis in Israel may be linked to epidemic clones
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In Israel, the high incidence of pregnancy-related listeriosis may be caused by specific epidemic clones disseminating in the country, according to recent findings.
In a retrospective cohort study, researchers reviewed data from the National Listeria Reference Laboratory, the Ministry of Health Epidemiological Bureau and records from the clinical microbiology labs from all hospitals in Israel to identify all Listeria monocytogenes infections in the country during a 10-year period.
The researchers identified pregnancy-related listeriosis when clinical specimens of hospitalized pregnant women revealed L. monocytogenes isolates. Cases in which L. monocytogenes was identified in neonates (up to 60 days after birth) were also identified as pregnancy-related. For all cases determined to be pregnancy-related listeriosis, the researchers recorded the demographics, comorbid conditions, trimester at diagnosis, treatment and outcome.
From the National Listeria Reference Laboratory, the investigators obtained isolates of pregnancy-related listeriosis and analyzed them using pulsed-field gel electrophoresis (PFGE).
The researchers identified 166 pregnancy-related listeriosis cases, which equaled an annual incidence of five to 25 cases per 100,000 births. Cases in which infection was identified in the second trimester were frequently associated with fetal death (54.2%), whereas cases identified in the third trimester were more often linked to preterm labor and abnormal fetal heart rate (52.3%, P=.001). The viability of the fetus was low in second-trimester cases (29.2%) and was significantly higher (93.8%) in the third trimester. The chances of fetal survival were found to increase by 33% (OR=1.331, 95% CI, 1.189-1.489) with each additional week of pregnancy. Only one case of maternal death was documented. In pregnancy-related cases, L. monocytogenes serotype 4b was more common than in non-pregnancy-associated cases (79.5% vs. 61.3%, P=.011). PFGE analysis revealed that 35.7% of pregnancy-related cases between 2001 and 2007 were attributable to a single pulsotype, a clone closely related to the gastroenteritis-associated HPB2262, and to the invasive USA ScottA L. monocytogenes strains.
“In this study we reported the first comprehensive survey from Israel regarding pregnancy-related listeriosis, and it is one of the largest cohorts in the literature,” the researchers wrote. “Obviously, the high rates of cases may suggest an urgent need for prevention action, including education of pregnant women on avoiding unsafe food, food hygiene and decontamination.”
Disclosure: The researchers report no relevant financial disclosures.
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