The prevalence of Listeria species in different food items of animal and plant origin in Ethiopia: a systematic review and meta-analysis

Prevalence, Antimicrobial Resistance, and Characterization of Listeria Spp. Isolated from Various Sources in Ethiopia: A Comprehensive Review

Listeriosis is an important foodborne zoonotic disease affecting humans and animals in Ethiopia. This review aims to synthesize the epidemiology, prevalence, distribution, and antimicrobial resistance of Listeria species in the country. The literature reveals a widespread occurrence of Listeria infection in humans, animals, and food products, with an average prevalence of 21.6% for Listeria species and 6.9% for L. monocytogenes. Three sequence types (STs) of L. monocytogenes (2, 145, and 18) and twelve STs of L. innocua (1489, 1619, 603, 537, 1010, 3186, 492, 3007, 1087, 474, 1008, and 637) were reported from milk and dairy products. Contamination rates ranged from 4.1% to 42.9% across livestock, dairy, slaughterhouses, and processing facilities, indicating faults in production practices. Sporadic human listeriosis outbreaks have occurred since 1967, causing meningitis, perinatal infections, and deaths, with recent studies showing L. monocytogenes isolation in up to 10.4% of febrile patients, confirming foodborne transmission. Non-pathogenic Listeria species were also common on farms and in facilities. Ovine listeriosis poses a threat to Ethiopia's sheep and goat industries, with over 40% seroprevalence in some herds. Comprehensive control measures across the food chain are needed to curb contamination and protect public health. Isolates from various foods show antibiotic resistance to first-line agents but susceptibility to others like gentamicin and cephalosporins. In conclusion, this review synthesizes evidence on Listeria distribution in Ethiopia's food system and disease burden, highlighting the need for improved food safety policies and awareness.

Comparison of prevalence, characterization, antimicrobial resistance and pathogenicity of foodborne Listeria monocytogenes in recent 5 years in Japan

This study investigated the prevalence, serotype, antimicrobial resistance (AMR), virulence potential, and biofilm formation of Listeria monocytogenes isolated in 2022 in Japan and compared their profiles with those of isolates in 2012 and 2017. A total of 85 chicken samples were randomly collected from different supermarkets in Fukuoka in 2022. L. monocytogenes were isolated by conventional method and characterized by MALDI-TOF MS. Among 85 samples tested in 2022, 9 (10.6%) were positive for L. monocytogenes and 17 strains were isolated from the positive samples. The isolates were serotyped as 1/2b (41.2%), 3a (29.4%), 3b (23.5%) and 1/2a (5.9%). Antimicrobial susceptibility tests of the 2022 isolates showed susceptibility to majority of the antibiotics, except cefoxitin, oxacillin, and fosfomycin. Compared to the previous surveillance results, the prevalence of L. monocytogenes in 2022 (10.6%) was significantly lower (p < 0.05) than those of the isolates in 2017 (24%) and 2012 (52.9%). The distribution of serotypes 1/2a and 1/2b decreased over time, and serotype 4b was not detected in the 2022 isolates. The proportion of multidrug resistant strains in 2022 (16.7%) was significantly lower than those in 2012 (46.7%) and 2017 (82.6%). Moreover, a total of 36 isolates (12 isolates/ year) were used to detect the virulence genes (hlyA, plcA, clpC, and inlA) and biofilm-forming capacity. Most of the isolates from different years harboured four virulence genes. The biofilm formation of the 2022 isolates was significantly weaker (p < 0.05) than those of the 2012 and 2017 isolates. Thus, despite the low rates of contamination in chicken meat and AMR of the isolates, virulent L. monocytogenes contamination in food should still be acknowledged.

Genetic diversity and known virulence genes in Listeria innocua strains isolated from cattle abortions and farm environment

Listeria innocua is considered as non-pathogenic bacteria living in an environment although several cases of immunocompromised humans and ruminant listeriosis infections have been reported. Previously, L. innocua was identified as a potential pathogen and virulence in association with L. monocytogenes PrfA dependent virulence (LIPI-1) gene cluster was demonstrated in hemolytic L. innocua. L. innocua usually considered non-pathogenic versus pathogenic L. monocytogenes and L. ivanovii because of the main virulence gene loss. There are limited studies and reports available about L. innocua-caused illness in cattle. A total of 18 STs were identified in cattle abortions while 17 STs in the farm environment with majority of STs were present in both abortions and environmental samples. Genome sequencing showed that in one farm identical L. innocua clones were represented in water, feed, soil, and faeces sample groups, suggesting that animals most likely through the faecal shedding may remain as the main source of L. innocua in a farm environment. Out of all L. innocua isolates PrfA-dependent virulence genes were not found in aborted foetuses isolates and environmental L. innocua isolate groups; however, in 20% of isolates a complete LIPI-3 pathogenicity island encoding listeriolysin S was identified. In this study, we demonstrated that genetically diverse L. innocua clones were widely distributed in cattle farm environment and certain isolates had a significant pathogenicity potential for cattle, thus causing adverse health effects, including abortions.

Virulence Characteristics and Distribution of the Pathogen Listeria ivanovii in the Environment and in Food

Listeria ivanovii and L. monocytogenes, are the only pathogenic species of the genus Listeria and share many virulence factors and mechanisms of pathogenicity. L. ivanovii shows host tropism towards small ruminants and rodents and much lower virulence for humans compared to L. monocytogenes. However, severe infections caused by L. ivanovii, resulting in bacteremia, abortion and stillbirth, occasionally occurred in immunocompromised persons and in pregnant women, while in immunocompetent hosts L. ivanovii can cause gastroenteritis. In this review, the updated knowledge on virulence aspects and distribution of L. ivanovii in the environment and in food is summarized. Recent research on its virulence characters at genome level gave indications on how pathogenicity evolved in this bacterial species. As for L. monocytogenes, L. ivanovii infections occurred after the ingestion of contaminated food, so an overview of reports regarding its distribution in food products was carried out to obtain indications on the categories of foods exposed to contamination by L. ivanovii. It was found that a wide variety of food products can be a source of this microorganism and that, like L. monocytogenes, L. ivanovii is able to persist in the food production environment. Studies on its ability to grow in enrichment and isolation media suggested that its occurrence in nature might be underestimated. Moreover, virulence varies among strains for differences in virulence character regulation, presence/absence of genetic regions and the possible instability of a Listeria pathogenicity genomic island, LIPI-2, which is unique to L. ivanovii. We can conclude that L. ivanovii, as a possible pathogen for animals and humans, requires more focused investigations regarding its occurrence in the environment and in food and on intra-species variability of pathogenic potential.

The prevalence of Listeria monocytogenes in meat products in Brazil: A systematic literature review and meta-analysis

Listeria monocytogenes, a foodborne pathogen that causes human listeriosis, is commonly found in meat products. This study aimed to estimate the prevalence of L. monocytogenes in a variety of Brazilian meat products, using a meta-analysis of data from the literature. A total of 29 publications from five databases, published between January 1, 2009, and December 31, 2019, were included in the study. Estimated by the random-effects model, the combined prevalence of L. monocytogenes was 13%, ranging from 0 to 59%. The combined prevalence of L. monocytogenes was 14% and 11% for raw meat and ready-to-eat (RTE) meat, respectively. The prevalence of L. monocytogenes was higher in the swine species' meat products and the Southeast region of Brazil. Regarding the type of establishment, it was the retail market that presented the highest combined prevalence rate (19%). The most prevalent serotypes of L. monocytogenes were 4b, 1/2a, 1/2b, and 1/2c. The knowledge of differences in the prevalence levels of L. monocytogenes in different meat products can guide in its efficient control by the competent authorities and by industry.

Selected Livestock-Associated Zoonoses as a Growing Challenge for Public Health

The aim of this paper is to review the most significant livestock-associated zoonoses. Human and animal health are intimately connected. This idea has been known for more than a century but now it has gained special importance because of the increasing threat from zoonoses. Zoonosis is defined as any infection naturally transmissible from vertebrate animals to humans. As the frequency and prevalence of zoonotic diseases increase worldwide, they become a real threat to public health. In addition, many of the newly discovered diseases have a zoonotic origin. Due to globalization and urbanization, some of these diseases have already spread all over the world, caused by the international flow of goods, people, and animals. However, special attention should be paid to farm animals since, apart from the direct contact, humans consume their products, such as meat, eggs, and milk. Therefore, zoonoses such as salmonellosis, campylobacteriosis, tuberculosis, swine and avian influenza, Q fever, brucellosis, STEC infections, and listeriosis are crucial for both veterinary and human medicine. Consequently, in the suspicion of any zoonoses outbreak, the medical and veterinary services should closely cooperate to protect the public health.