Nationwide outbreak of invasive listeriosis associated with consumption of meat products in health care facilities, Germany, 2014–2019

Abstract

Objectives: Invasive listeriosis is a severe foodborne infection caused by Listeria (L.) monocytogenes. The aim of this investigation was to verify and describe a molecular cluster of listeriosis patients and identify factors leading to this outbreak. Methods: Whole genome sequencing and core genome multilocus sequence typing were used for subtyping L. monocytogenes isolates from listeriosis cases and food samples in Germany. Patient interviews and investigational tracing of foodstuffs offered in health-care facilities (HCF), where some of the cases occurred, were conducted. Results: We identified a German-wide listeriosis outbreak with 39 genetically related cases occurring between 2014 and 2019. Three patients died as a result of listeriosis. After identification of HCF in different regions of Germany for at least 13 cases as places of exposure, investigational tracing of food supplies in six prioritized HCF revealed meat products from one company (X) as a commonality. Subsequently the outbreak strain was analysed in six isolates from ready-to-eat meat products and one isolate from the production environment of company X. No further Sigma1 cases were detected after recall of the meat products from the market and closure of company X (as of August 2020). Conclusions: Interdisciplinary efforts including whole genome sequencing, epidemiological investigations in patients and investigational tracing of foods were essential to identify the source of infections, and thereby prevent further illnesses and deaths. This outbreak underlines the vulnerability of hospitalized patients for foodborne diseases, such as listeriosis. Food producers and HCF should minimize the risk of microbiological hazards when producing, selecting and preparing food for patients.

Complete Genome Sequences of Three Clinical Listeria monocytogenes Sequence Type 8 Strains from Recent German Listeriosis Outbreaks

“…Three outbreaks recently detected were caused by PCR serogroup IIa clones belonging to multilocus sequence typing (MLST) sequence type 8 (ST8) (3,4). Using 1,701-locus core-genome MLST (cgMLST), we further assigned cgMLST complex types 1248 (CT1248) (from the outbreak referred to as Alpha1), CT2521 (Sigma1), and CT5004 (Pi4; Table 1) to these clones (3)(4)(5). This report announces the completion of closed genome sequences of one representative strain for each of these outbreaks (Table 1).…”

“…For short-read sequencing, strain 19-05816 was cultivated for 16 h in BHI broth at 37°C. The isolation of chromosomal DNA and library preparation were performed as described previously (4). Sequencing was carried out on a NextSeq sequencer, in 2 Â 150-bp mode, generating 3,318,986 reads.…”

Healthcare-associated foodborne outbreaks in high-income countries: a literature review and surveillance study, 16 OECD countries, 2001 to 2019*

“…So far, literature reviews have covered pathogens responsible for HA-FBO, including Salmonella [6], Listeria monocytogenes [7][8][9] and norovirus [10,11] and focused on microbiological food safety issues in healthcare settings [5,12]. Between 2014 and 2019, a listeriosis outbreak in Germany affected 13 cases who had an inpatient stay in 12 different HCF during the incubation period [13]. In the United Kingdom (UK) in 2019, nine listeriosis cases of which seven died, had consumed sandwiches in seven HCF during the incubation period [14].…”

A Nosocomial Outbreak of Invasive Listeriosis in An Italian Hospital: Epidemiological and Genomic Features

“…Whereas a direct or indirect person-to-person transmission was suggested in some L. monocytogenes nosocomial outbreaks, especially among neonates [ 5 , 15 , 16 ], the majority of transmissions turned out to be linked to contaminated food products such as vegetables [ 17 ], sandwiches [ 18 ], dairy products such as pasteurized milk cheese [ 19 ], ice cream [ 20 ], or milkshakes [ 21 ], meat jelly [ 22 ], or other meat products [ 23 ]. In particular, in 2015 in a Washington State hospital, a case of hospital-acquired listeriosis resulted to be closely related to two previous cases that occurred in the same hospital one year before, and linked to a milkshake machine persistently contaminated despite repeated cleaning and sanitation [ 24 ].…”