Listeriosis Outbreaks and Associated Food Vehicles, United States, 1998-2008

Emerging Infectious Diseases (Impact Factor: 7.33). 01/2013; 19(1):1-9. DOI: 10.3201/eid1901.120393
Source: PubMed

ABSTRACT Listeria monocytogenes, a bacterial foodborne pathogen, can cause meningitis, bacteremia, and complications during pregnancy. This report summarizes listeriosis outbreaks reported to the Foodborne Disease Outbreak Surveillance System of the Centers for Disease Control and Prevention during 1998-2008. The study period includes the advent of PulseNet (a national molecular subtyping network for outbreak detection) in 1998 and the Listeria Initiative (enhanced surveillance for outbreak investigation) in 2004. Twenty-four confirmed listeriosis outbreaks were reported during 1998-2008, resulting in 359 illnesses, 215 hospitalizations, and 38 deaths. Outbreaks earlier in the study period were generally larger and longer. Serotype 4b caused the largest number of outbreaks and outbreak-associated cases. Ready-to-eat meats caused more early outbreaks, and novel vehicles (i.e., sprouts, taco/nacho salad) were associated with outbreaks later in the study period. These changes may reflect the effect of PulseNet and the Listeria Initiative and regulatory initiatives designed to prevent contamination in ready-to-eat meat and poultry products.

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    ABSTRACT: Background Genome subtyping approaches could provide useful epidemiological information regarding food pathogens. However, the full genomic diversity of strains that show similar subtyping results has not yet been completely explored. Most subtyping methods are based on the differences of only a portion of the genome. We investigated two draft genome sequences of Listeria monocytogenes strain F2-382 and NIHS-28, which have been identified as closely related strains by subtyping (identical multi-virulence-locus sequence typing and multiple-locus variable number tandem repeat analysis sequence types and very similar pulsed-field gel electrophoresis patterns), despite their different sources.ResultsTwo closely related strains were compared by genome structure analysis, recombination analysis, and single nucleotide polymorphism (SNP) analysis. Both genome structure analysis and recombination analysis showed that these two strains are more closely related than other strains, from a whole-genome perspective. However, the analysis of SNPs indicated that the two strains differ at the single nucleotide level.Conclusion We show the relationship between the results of genome subtyping and whole-genome sequencing. It appears that the relationships among strains indicated by genome subtyping methods are in accord with the relationships indicated by whole-genome analysis. However, our results also indicate that the genetic distance between the closely related strains is greater than that between clonal strains. Our results demonstrate that subtyping methods using a part of the genome are reliable in assessing the genetic distance of the strains. Furthermore, the genetic differences in the same subtype strains may provide useful information to distinguish the bacterial strains.
    BMC Microbiology 12/2014; 14(1):309. DOI:10.1186/s12866-014-0309-0 · 2.98 Impact Factor
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    ABSTRACT: Contaminated produce has been identified as the cause of several listeriosis outbreaks in recent years. Listeria monocytogenes is widely distributed in the environment and complete prevention of produce contamination is therefore challenging. Mitigation options that reduce contamination on produce are valuable, especially for produce commodities that are commonly consumed fresh or minimally processed. We performed a systematic review and meta-analysis of the available peer-reviewed literature to evaluate the efficacy of liquid fresh produce wash compounds in reducing produce contamination with L. monocytogenes, and derive quantitative estimates of treatment efficacy for a variety of common liquid fresh produce wash compounds. Treatment efficacy differed considerably across produce commodities, with liquid fresh produce wash compounds generally showing considerably greater efficacy for some tested commodities than for other commodities. Most but not all of the evaluated liquid fresh produce wash compounds were significantly more effective in reducing L monocytogenes contamination than water alone, with mean reductions in L. monocytogenes levels ranging from less than 1 log(10) cfu to more than 5 log(10) cfu. Liquid fresh produce wash compounds are therefore a possible tool for reducing contamination with L. monocytogenes, for certain produce commodities.
    Food Control 12/2014; 46:430-440. DOI:10.1016/j.foodcont.2014.06.011 · 2.82 Impact Factor
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    ABSTRACT: Background. In 2011, a multistate outbreak of listeriosis linked to contaminated cantaloupes raised concerns that many pregnant women might have been exposed to Listeria monocytogenes. Listeriosis during pregnancy can cause fetal death, premature delivery, and neonatal sepsis and meningitis. Little information is available to guide healthcare providers who care for asymptomatic pregnant women with suspected L. monocytogenes exposure. Methods. We tracked pregnancy-associated listeriosis cases using reportable diseases surveillance and enhanced surveillance for fetal death using vital records and inpatient fetal deaths data in Colorado. We surveyed 1,060 pregnant women about symptoms and exposures. We developed three methods to estimate how many pregnant women in Colorado ate the implicated cantaloupes, and we calculated attack rates. Results. One laboratory-confirmed case of listeriosis was associated with pregnancy. The fetal death rate did not increase significantly compared to preoutbreak periods. Approximately 6,500–12,000 pregnant women in Colorado might have eaten the contaminated cantaloupes, an attack rate of ∼1 per 10,000 exposed pregnant women. Conclusions. Despite many exposures, the risk of pregnancy-associated listeriosis was low. Our methods for estimating attack rates may help during future outbreaks and product recalls. Our findings offer relevant considerations for management of asymptomatic pregnant women with possible L. monocytogenes exposure.
    Infectious Diseases in Obstetrics and Gynecology 02/2015; 2015. DOI:10.1155/2015/201479

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