Outbreak of<i>Listeria monocytogenes</i>infections linked to a pasteurized ice cream product served to hospitalized patients

Rietberg, Krista; Lloyd, John; Melius, Beth; Wyman, Peter A.; Treadwell, Reagan; Olson, Gina; Kang, Mi-Gyeong; Duchin, Jeffrey S.

doi:10.1017/s0950268815003039

Cited by 26 publications

(32 citation statements)

References 7 publications

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“…An environmental isolate from Company A and an environmental isolate from Company B were collected in early 2015 as Company B purchased dairy ingredients from Company A [7, 8]. Isolates were also collected in November 2015 from the patient, the ice cream that remained in and were dispensed from the milkshake maker in Hospital X, and the environmental samples from different areas (e.g., side walls of internal parts and nozzle assembly) of the milkshake maker.…”

Section: Methodsmentioning

confidence: 99%

“…A 2010–2015 multistate listeriosis outbreak was linked to contaminated ice cream manufactured in the southern United States [6]. In late 2014, a different listeriosis outbreak in Washington State, unrelated to the 2010–2015 multistate outbreak, occurred in a hospital (Hospital X) in the Pacific Northwest of the United States, involving patients hospitalized for other medical conditions prior to exposure to milkshakes made from contaminated ice cream mixes manufactured in a company (Company A) [7]. Following the investigation of the Washington State outbreak, intensive cleaning and sanitizing were conducted in the facility and hospital kitchen, although cleaning of the soft serve shake freezer took extra efforts, because milkshake was made inside the machine and disassembly was required for thorough cleaning [7].…”

Section: Introductionmentioning

confidence: 99%

“…In late 2014, a different listeriosis outbreak in Washington State, unrelated to the 2010–2015 multistate outbreak, occurred in a hospital (Hospital X) in the Pacific Northwest of the United States, involving patients hospitalized for other medical conditions prior to exposure to milkshakes made from contaminated ice cream mixes manufactured in a company (Company A) [7]. Following the investigation of the Washington State outbreak, intensive cleaning and sanitizing were conducted in the facility and hospital kitchen, although cleaning of the soft serve shake freezer took extra efforts, because milkshake was made inside the machine and disassembly was required for thorough cleaning [7]. In November 2015, another patient from Hospital X, hospitalized for other conditions prior to exposure to L. monocytogenes , was linked to contaminated milkshakes by pulsed-field gel electrophoresis (PFGE) [8].…”

Section: Introductionmentioning

confidence: 99%

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Whole genome sequencing analyses of Listeria monocytogenes that persisted in a milkshake machine for a year and caused illnesses in Washington State

Pérez-Osorio

Wang

et al. 2017

BMC Microbiol

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BackgroundIn 2015, in addition to a United States multistate outbreak linked to contaminated ice cream, another outbreak linked to ice cream was reported in the Pacific Northwest of the United States. It was a hospital-acquired outbreak linked to milkshakes, made from contaminated ice cream mixes and milkshake maker, served to patients. Here we performed multiple analyses on isolates associated with this outbreak: pulsed-field gel electrophoresis (PFGE), whole genome single nucleotide polymorphism (SNP) analysis, species-specific core genome multilocus sequence typing (cgMLST), lineage-specific cgMLST and whole genome-specific MLST (wgsMLST)/outbreak-specific cgMLST. We also analyzed the prophages and virulence genes.ResultsThe outbreak isolates belonged to sequence type 1038, clonal complex 101, genetic lineage II. There were no pre-mature stop codons in inlA. Isolates contained Listeria Pathogenicity Island 1 and multiple internalins. PFGE and multiple whole genome sequencing (WGS) analyses all clustered together food, environmental and clinical isolates when compared to outgroup from the same clonal complex, which supported the finding that L. monocytogenes likely persisted in the soft serve ice cream/milkshake maker from November 2014 to November 2015 and caused 3 illnesses, and that the outbreak strain was transmitted between two ice cream production facilities. The whole genome SNP analysis, one of the two species-specific cgMLST, the lineage II-specific cgMLST and the wgsMLST/outbreak-specific cgMLST showed that L. monocytogenes cells persistent in the milkshake maker for a year formed a unique clade inside the outbreak cluster. This clustering was consistent with the cleaning practice after the outbreak was initially recognized in late 2014 and early 2015. Putative prophages were conserved among prophage-containing isolates. The loss of a putative prophage in two isolates resulted in the loss of the AscI restriction site in the prophage, which contributed to their AscI-PFGE banding pattern differences from other isolates.ConclusionsThe high resolution of WGS analyses allowed the differentiation of epidemiologically unrelated isolates, as well as the elucidation of the microevolution and persistence of isolates within the scope of one outbreak. We applied a wgsMLST scheme which is essentially the outbreak-specific cgMLST. This scheme can be combined with lineage-specific cgMLST and species-specific cgMLST to maximize the resolution of WGS.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Whole genome sequencing analyses of Listeria monocytogenes that persisted in a milkshake machine for a year and caused illnesses in Washington State

Pérez-Osorio

Wang

et al. 2017

BMC Microbiol

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“…This recommendation is despite pasteurized dairy-based ice cream products being implicated in two recent Listeria outbreaks in the United States. [6–7]. …”

mentioning

confidence: 99%

“…A PHSKC investigation of the initial 2014 outbreak determined that a locally produced, commercial pasteurized ice cream mix, was the source of the L. monocytogenes outbreak [7]. The 2014 outbreak resulted in the recall of all products produced by the ice cream manufacturer, temporary closure of the manufacturer, and suspension of shake freezer machine use at the hospital [7].…”

mentioning

confidence: 99%

Hospital-acquired listeriosis linked to a persistently contaminated milkshake machine

et al. 2017

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SUMMARY One case of hospital-acquired listeriosis linked to milkshakes produced in a commercial-grade shake freezer machine that remained contaminated following a previous outbreak of listeriosis associated with a pasteurized, dairy-based ice cream product at the same hospital despite repeated cleaning and sanitation. Healthcare facilities should be aware of the potential for prolonged Listeria contamination of food service equipment. In addition, healthcare providers should consider counseling persons who have an increased risk for Listeria infections regarding foods that have caused Listeria infections. The prevalence of persistent Listeria contamination of commercial-grade milkshake machines in healthcare facilities and the risk associated with serving dairy-based ice cream products to hospitalized patients at increased risk for invasive L. monocytogenes infections should be further evaluated.

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Dairy production: microbial safety of raw milk and processed milk products

Ntuli

Sibanda

Elegbeleye

et al. 2023

Present Knowledge in Food Safety

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Outbreak ofListeria monocytogenesinfections linked to a pasteurized ice cream product served to hospitalized patients

Cited by 26 publications

References 7 publications

Whole genome sequencing analyses of Listeria monocytogenes that persisted in a milkshake machine for a year and caused illnesses in Washington State

Whole genome sequencing analyses of Listeria monocytogenes that persisted in a milkshake machine for a year and caused illnesses in Washington State

Hospital-acquired listeriosis linked to a persistently contaminated milkshake machine

Dairy production: microbial safety of raw milk and processed milk products

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