Changing Pattern of Human Listeriosis, England and Wales, 2001–2004

Disease has reemerged, mainly in patients ≥60 years of age with bacteremia

Genomic epidemiology of the clinically dominant clonal complex 1 in the Listeria monocytogenes population in the UK

Listeria monocytogenes is a food-borne pathogen, typically affecting the elderly, immunocompromised patients and pregnant women. The aim of this study was to determine the population structure of L. monocytogenes clonal complex 1 (CC1) in the UK and describe the genomic epidemiology of this clinically significant CC. We interrogated a working dataset of 4073 sequences of L. monocytogenes isolated between January 2015 and December 2020 from human clinical specimens, food and/or food-production environments. A minimum spanning tree was reconstructed to determine the population structure of L. monocytogenes in the UK. Subsequent analysis focused on L. monocytogenes CC1, as the cause of the highest proportion of invasive listeriosis in humans. Sequencing data was integrated with metadata on food and environmental isolates, and information from patient questionnaires, including age, sex and clinical outcomes. All isolates either belonged to lineage I (n=1299/4073, 32%) or lineage II (n=2774/4073, 68%), with clinical isolates from human cases more likely to belong to lineage I (n=546/928, 59%) and food isolates more likely to belong to lineage II (n=2352/3067, 77%). Of the four largest CCs, CC1 (n=237) had the highest proportion of isolates from human cases of disease (CC1 n=160/237, 67.5 %; CC121 n=13/843, 2 %; CC9 n=53/360, 15 %; CC2 n=69/339, 20%). Within CC1, most cases were female (n=95/160, 59%, P=0.01771) and the highest proportion of cases were in people >60 years old (39/95, 41%, P=1.314×10−6) with a high number of them aged 20–39 years old (n=35/95, 37%) most linked to pregnancy-related listeriosis (n=29/35, 83%). Most of the male cases were in men aged over 60 years old (40/65, 62%), and most of the fatal cases in both males and females were identified in this age group (42/55, 76%). Phylogenetic analysis revealed 23 5 SNP single linkage clusters comprising 80/237 (34 %) isolates with cluster sizes ranging from 2 to 19. Five 5 SNP clusters comprised isolates from human cases and an implicated food item. Expanding the analysis to 25 SNP single linkage clusters resolved an additional two clusters linking human cases to a potential food vehicle. Analysis of demographic and clinical outcome data identified CC1 as a clinically significant cause of invasive listeriosis in the elderly population and in women of child-bearing age. Phylogenetic analysis revealed the population structure of CC1 in the UK comprised small, sparsely populated genomic clusters. Only clusters containing isolates from an implicated food vehicle, or food processing or farming environments, were resolved, emphasizing the need for clinical, food and animal-health agencies to share sequencing data in real time, and the importance of a One Health approach to public-health surveillance of listeriosis

Dynamics of Salmonella enterica and antimicrobial resistance in the Brazilian poultry industry and global impacts on public health

Non-typhoidal Salmonella enterica is a common cause of diarrhoeal disease; in humans, consumption of contaminated poultry meat is believed to be a major source. Brazil is the world’s largest exporter of chicken meat globally, and previous studies have indicated the introduction of Salmonella serovars through imported food products from Brazil. Here we provide an in-depth genomic characterisation and evolutionary analysis to investigate the most prevalent serovars and antimicrobial resistance (AMR) in Brazilian chickens and assess the impact to public health of products contaminated with S. enterica imported into the United Kingdom from Brazil. To do so, we examine 183 Salmonella genomes from chickens in Brazil and 357 genomes from humans, domestic poultry and imported Brazilian poultry products isolated in the United Kingdom. S. enterica serovars Heidelberg and Minnesota were the most prevalent serovars in Brazil and in meat products imported from Brazil into the UK. We extended our analysis to include 1,259 publicly available Salmonella Heidelberg and Salmonella Minnesota genomes for context. The Brazil genomes form clades distinct from global isolates, with temporal analysis suggesting emergence of these Salmonella Heidelberg and Salmonella Minnesota clades in the early 2000s, around the time of the 2003 introduction of the Enteritidis vaccine in Brazilian poultry. Analysis showed genomes within the Salmonella Heidelberg and Salmonella Minnesota clades shared resistance to sulphonamides, tetracyclines and beta-lactams conferred by sul2, tetA and blaCMY-2 genes, not widely observed in other co-circulating serovars despite similar selection pressures. The sul2 and tetA genes were concomitantly carried on IncC plasmids, whereas blaCMY-2 was either co-located with the sul2 and tetA genes on IncC plasmids or independently on IncI1 plasmids. Long-term surveillance data collected in the UK showed no increase in the incidence of Salmonella Heidelberg or Salmonella Minnesota in human cases of clinical disease in the UK following the increase of these two serovars in Brazilian poultry. In addition, almost all of the small number of UK-derived genomes which cluster with the Brazilian poultry-derived sequences could either be attributed to human cases with a recent history of foreign travel or were from imported Brazilian food products. These findings indicate that even should Salmonella from imported Brazilian poultry products reach UK consumers, they are very unlikely to be causing disease. No evidence of the Brazilian strains of Salmonella Heidelberg or Salmonella Minnesota were observed in UK domestic chickens. These findings suggest that introduction of the Salmonella Enteritidis vaccine, in addition to increasing antimicrobial use, could have resulted in replacement of salmonellae in Brazilian poultry flocks with serovars that are more drug resistant, but less associated with disease in humans in the UK. The plasmids conferring resistance to beta-lactams, sulphonamides and tetracyclines likely conferred a competitive advantage to the Salmonella Minnesota and Salmonella Heidelberg serovars in this setting of high antimicrobial use, but the apparent lack of transfer to other serovars present in the same setting suggests barriers to horizontal gene transfer that could be exploited in intervention strategies to reduce AMR. The insights obtained reinforce the importance of One Health genomic surveillance

Molecular Epidemiological Analysis of Cryptosporidium Isolates from Humans and Animals by Using a Heteroduplex Mobility Assay and Nucleic Acid Sequencing Based on a Small Double-Stranded RNA Element

Two extrachromosomal double-stranded RNA (dsRNA) elements occur in Cryptosporidium parvum. A heteroduplex mobility assay (HMA) was developed for the rapid characterization of sequence diversity in a 173-bp fragment of the small dsRNA element of Cryptosporidium with either a natural sequence from Cryptosporidium meleagridis or a synthetic sequence as reference DNA. The 173-bp fragment was generated from 265 samples of whole feces (242 from humans and 18 from livestock with C. parvum genotype 1 or 2, 4 from humans with Cryptosporidium felis, and 1 from a human with C. meleagridis). The HMA method identified 21 patterns in C. parvum (8 in genotype 1, 12 in genotype 2, and a type common to both genotypes), 4 patterns in C. felis, and 1 pattern in C. meleagridis. All patterns were confirmed as distinct by DNA sequencing. For genotype 1, a single HMA type was found in 89% of samples: 64 of 65 cases from three waterborne outbreaks, all 16 cases from eight intrafamilial outbreaks, and 17 of 28 sporadic cases. Among the remaining 11 sporadic cases due to genotype 1, seven other HMA types were detected. For genotype 2, a single HMA type was found in 72% of samples: 36 of 43 cases from three waterborne outbreaks, 11 of 15 cases from seven intrafamilial outbreaks, 44 of 75 sporadic cases, and all 18 samples from livestock. Within the intrafamilial outbreaks, two other HMA types were identified: the same HMA type was detected in samples from cases within the same outbreak. Among the sporadic cases due to genotype 2, 10 additional HMA types were detected

Assessment of the Microbiological Quality of Meat Pies from Retail Sale in England 2013.

Outbreaks of foodborne illness caused by Bacillus cereus and Listeria monocytogenes in England associated with meat pie consumption were detected in 2012. To obtain baseline data for pies unrelated to outbreaks, 862 samples of ready-to-eat meat pies were collected at retail or from catering facilities in England in 2013 and examined to enumerate food-poisoning bacteria and indicator organisms using Organization for Standardization (ISO) methods for Listeria spp. including L. monocytogenes (ISO 11290), Clostridium perfringens (ISO 21528), coagulase-positive staphylococci including Staphylococcus aureus (ISO 6888), Bacillus spp. including B. cereus (ISO 1737), Escherichia coli (ISO 16649), Enterobacteriaceae (ISO 21528), and aerobic colony counts (ACCs; ISO 4833). Microbiological quality was satisfactory in 94% of samples, borderline in 5%, and unsatisfactory in 1%. The proportion of pies from markets that were borderline or unsatisfactory significantly increased, and the proportion of borderline or unsatisfactory pies from supermarkets significantly decreased. Among the refrigerated (0 to 15°C) pies, microbiological quality significantly decreased in pies stored at >8°C and further significantly decreased at in pies stored at ambient temperature (>15 to 25°C). Samples collected at 25 to 40°C had the highest proportion of borderline or unsatisfactory results, but results improved in pies stored at >40°C. The most common cause for borderline or unsatisfactory results was elevated ACCs (5% of all samples). Within the individual microbiological parameters, borderline or unsatisfactory results resulted from elevated Enterobacteriaceae or Bacillus levels (10 samples for each), C. perfringens levels (2 samples), and S. aureus or E. coli levels (1 sample each). L. monocytogenes was recovered from one pie at <10 CFU/g. A literature review revealed a range of microbiological hazards responsible for food poisoning and meat pie consumption, and surveillance data from 1992 to 2012 from England indicated that C. perfringens was the most commonly reported cause of outbreaks of foodborne illness

Disease Presentation in Relation to Infection Foci for Non-Pregnancy-Associated Human Listeriosis in England and Wales, 2001 to 2007▿

Listeriosis is a rare but severe food-borne disease, affecting unborn or newly delivered infants, the elderly, and the immunocompromised. The epidemiology of listeriosis in England and Wales changed between 2001 and 2007, with more patients ≥60 years old presenting with bacteremia (but without central nervous system [CNS] involvement). In order to explain this increase and understand the altered disease presentation, clinical, microbiological, and seasonal data on bacteremic cases of Listeria monocytogenes infection identified through national surveillance were compared with those for patients with CNS infections. Logistic regression analysis was applied while controlling for age. Bacteremic patients, who presented more frequently with gastrointestinal symptoms, were more likely to have underlying medical conditions than CNS patients. This was most marked in patients with malignancies, particularly digestive organ malignancies. Treatment to reduce stomach acid secretion modified the effect of nonmalignant underlying conditions on outcome, i.e., patients with an underlying condition who were not taking acid-suppressing medication were equally likely to have a bacteremic or a CNS infection. However, this type of therapy did not modify the effect of malignancies on the likelihood of having a bacteremic or a CNS infection. The increase in the incidence of human listeriosis among patients ≥60 years old in England and Wales between 2001 and 2007 appears to have occurred in those with cancer or other conditions whose treatment included acid-suppressing medication. Therefore, this vulnerable patient group needs specific dietary advice on avoiding risk factors for listeriosis