Listeriosis Outbreak in Dairy Cattle Caused by an Unusual Listeria Monocytogenes Serotype 4b Strain

Abstract

Abstract. A listeriosis outbreak, in dairy cattle, with a high case mortality and acute death after onset of symptoms was investigated using gross pathology and bacteriologic approaches, including molecular characterization of a clinical Listeria monocytogenes isolate. In a herd of 315 animals, 9 animals showed clinical symptoms consistent with listeriosis, including 3 animals that died within 2-4 days after acute onset of clinical signs, 4 animals that were euthanized, and 2 that survived. Initial EcoRI ribotyping and serotyping indicated that this outbreak was caused by an unusual L. monocytogenes serotype 4b strain, which was classified into lineage III. Further characterization of this isolate by DNA sequencing-based subtyping methods indicated that the strain responsible for this outbreak represented a unique genotype as supported by its classification into a new sigB allelic type, which has not been identified previously among .290 isolates, and by compelling phylogenetic evidence. While lineage III isolates are generally rare, they seem to be more common among L. monocytogenes isolates from animals with clinical signs of listeriosis. This is the first report of a particularly severe clinical course of disease associated with infection by a lineage III strain. The high prevalence of Listeria spp., including L. monocytogenes, in the farm environments may favor emergence and evolution of novel, and possibly more virulent, L. monocytogenes strains. Continued monitoring of animal listeriosis cases and outbreaks may not only improve animal health but also aid in the early discovery of newly emerging L. monocytogenes strains.

Ruminant Rhombencephalitis-Associated Listeria monocytogenes Strains Constitute a Genetically Homogeneous Group Related to Human Outbreak Strains

“…PFGE and other molecular subtyping techniques have rarely been used to characterize animal isolates of L. monocytogenes (24)(25)(26)(27)(28). In fact, most isolates of L. monocytogenes from animal clinical cases have been characterized by serotyping and ribotyping (5,20,29).…”

Spatial and Temporal Factors Associated with an Increased Prevalence of Listeria monocytogenes in Spinach Fields in New York State

“…After incubation for 48 h at 35°C (LMPM) and 30°C (MOX), up to four presumptive Listeria colonies were substreaked from LMPM and MOX onto brain heart infusion (BHI) agar plates (Becton Dickinson). The BHI plates were then incubated at 37°C for 24 h. Presumptive Listeria colonies were confirmed by PCR amplification and sequencing of the partial sigB gene as previously described (40)(41)(42). Isolates were identified to the allelic type (AT) by comparison of partial sigB sequences to an internal reference database (Food Safety Laboratory, Cornell University, Ithaca, NY) (40)(41)(42).…”

Validation of a Previously Developed Geospatial Model That Predicts the Prevalence of Listeria monocytogenes in New York State Produce Fields

“…After being incubated for 24 and 48 h, 50 l of each enrichment was streaked onto L. monocytogenes plating medium (LMPM) (Biosynth International, Itasca, IL) and modified Oxford agar (MOX) (Becton Dickinson); the plates were then incubated for 48 h at 35 and 30°C, respectively. Following incubation, up to four presumptive Listeria colonies were substreaked from MOX to LMPM and incubated at 35°C for 48 h. From all LMPM plates, up to four presumptive Listeria colonies were then substreaked onto brain heart infusion (BHI) plates (Becton Dickinson) and then incubated at 37°C for 24 h. The species and sigB allelic type of one presumptive Listeria colony per sample were determined by PCR amplification and sequencing of the partial sigB gene, as previously described (42)(43)(44).…”