Real-Time Whole-Genome Sequencing for Surveillance of Listeria monocytogenes, France.

During 2015-2016, we evaluated the performance of whole-genome sequencing (WGS) as a routine typing tool. Its added value for microbiological and epidemiologic surveillance of listeriosis was compared with that for pulsed-field gel electrophoresis (PFGE), the current standard method. A total of 2,743 Listeria monocytogenes isolates collected as part of routine surveillance were characterized in parallel by PFGE and core genome multilocus sequence typing (cgMLST) extracted from WGS. We investigated PFGE and cgMLST clusters containing human isolates. Discrimination of isolates was significantly higher by cgMLST than by PFGE (p<0.001). cgMLST discriminated unrelated isolates that shared identical PFGE profiles and phylogenetically closely related isolates with distinct PFGE profiles. This procedure also refined epidemiologic investigations to include only phylogenetically closely related isolates, improved source identification, and facilitated epidemiologic investigations, enabling identification of more outbreaks at earlier stages. WGS-based typing should replace PFGE as the primary typing method for L. monocytogenes.

Incidence of listeriosis and related mortality among groups at risk of acquiring listeriosis.

BACKGROUND: Listeriosis is a foodborne disease of significant public health concern that primarily affects persons with recognized underlying conditions or diseases that impair cell-mediated immunity. The degree of risk posed by the different underlying conditions is crucial to prioritize prevention programs that target the highest risk populations. METHODS: We reviewed cases of listeriosis reported in France from 2001 to 2008. Numbers of cases and deaths were tabulated by age and underlying condition. Measures of the impact of specific underlying conditions on the occurrence of listeriosis were calculated. For estimating the total number of persons living with specific diseases, we applied prevalence estimates of these diseases to the French population. Underlying conditions were ranked by the degree to which they increased the risk of listeriosis. RESULTS: From 2001 to 2008, 1959 cases of listeriosis were reported in France (mean annual incidence 0.39 per 100,000 residents). Compared with persons <65 years with no underlying conditions, those with chronic lymphocytic leukemia had a >1000-fold increased risk of acquiring listeriosis, and those with liver cancer; myeoloproliferative disorder; multiple myeloma; acute leukemia; giant cell arteritis; dialysis; esophageal, stomach, pancreas, lung, and brain cancer; cirrhosis; organ transplantation; and pregnancy had a 100-1000-fold increased risk of listeriosis. CONCLUSIONS: To be effective and acceptable to physicians and patients, listeriosis prevention strategies should be targeted based on evidence of increased risk. Stringent dietary guidance, to avoid specific foods with a high risk for Listeria contamination, should be targeted to pregnant women and to others at highest risk of listeriosis.

[Epidemiology of bacterial meningitis in France in 2002]. / Epidémiologie des méningites bactériennes en France en 2002.

In France, two sources of data, the mandatory notification and the hospital laboratory network EPIBAC, allow the health authorities to monitor the incidence of bacterial meningitis. In 2002 around 1,500 cases were estimated in France. The more common microorganisms were: Streptococcus pneumoniae 49% (incidence 1.19/100,000), Neisseria meningitidis 33% (incidence 0.83) and Streptococcus agalactiae (Streptococcus B) 11% (incidence 0.27). Listeria monocytogenes accounted for 4% of the cases (incidence 0.11) and Haemophilus influenzae accounted for 3% (incidence 0.08). Trends in incidence showed an increase of meningococci meningitis since 1996, a steady decrease of H. influenzae and Listeria meningitis since 1992, and a quasi stable number of pneumococci meningitis, streptococci B meningitis and tuberculosis meningitis in the last 10 years. The impact of preventive measures on the incidence of Listeria meningitis and H. influenzae b meningitis has been clearly demonstrated through the dramatic decrease of meningitis due to these microorganisms.