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Listeria spp. is a diverse genus of Gram-positive bacteria commonly present in the environment while L. monocytogenes and L. ivanovii are well known human and ruminant pathogens. The aim of the present study was to reveal the prevalence and genetic diversity of L. monocytogenes and other Listeria spp. and to identify the factors related to the abundance of pathogen at cattle farms. A total of 521 animal and environmental samples from 27 meat and dairy cattle farms were investigated and the genetic diversity of L. monocytogenes isolates was studied with WGS. The prevalence of Listeria was 58.9%, while of L. monocytogenes it was −11%. The highest prevalence of L. monocytogenes was found in the environment—soil samples near to manure storage (93%), mixed feed from the feeding trough and hay (29%), water samples from farms drinking trough (28%) and cattle feces (28%). Clonal complexes (CC) of CC37 (30%), CC11 (20%) and CC18 (17%) (all IIa serogroup) were predominant L. monocytogenes clones. CC18, CC37 and CC8 were isolated from case farms and CC37, CC11 and CC18 from farms without listeriosis history. Only one hypervirulent CC4 (1%) was isolated from the case farm. Sequence types (STs) were not associated with the isolation source, except for ST7, which was significantly associated with soil (p &lt, 0.05). The contamination of soil, feeding tables and troughs with L. monocytogenes was associated with an increased prevalence of L. monocytogenes at farms. Our study indicates the importance of hygienic practice in the prevention of the dissemination of L. monocytogenes in the cattle farm environment.

The aim of the present study was to detect the prevalence and antimicrobial resistance of fecal indicators and major foodborne pathogens in feces of calves and to identify the factors associated with increased prevalence of resistant bacteria on farms. Altogether, 180 rectal swabs were collected from 18 farms in Latvia. Samples were investigated to detect the prevalence and antimicrobial resistance of Escherichia coli, Enterococcus spp., Listeria monocytogenes, Yersinia enterocolitica, Salmonella spp., Staphylococcus aureus, and Campylobacter spp. Among all, 64% (74/110) of commensal E. coli, 100% (78/78) Enterococcus faecalis and 96% (22/23) Enterococcus faecium isolates were resistant at least to one antibiotic. The prevalence of extended-spectrum β-lactamase (ESBL)/AmpC-producing E. coli were 11.1% (20/180) with blaCTX-M, blaTEM, and blaCMY genes identified. Campylobacter jejuni (12.8%, 23/180) and Campylobacter coli (2.8%, 5/180) were the most resistant to tetracycline (61%, 14/23; 100%, 5/5) and fluoroquinolones (61%, 14/23; 100%, 5/5). Prevalence of L. monocytogenes was 0.6% (1/180) and S. aureus 1.7% (3/180). All samples were Salmonella and Y. enterocolitica negative. Farm size, bought calves, contact with other calves, and antimicrobial treatment of cows were associated with increased prevalence of resistant E. coli and Enterococcus spp. Despite the low overall usage of antimicrobials in Latvia, the high rates of antimicrobial resistance in fecal indicators and Campylobacter, in addition to the high prevalence of ESBL-producing E. coli, highlights the necessity for the prudent use of antimicrobials in dairy farms in Latvia.

Listeria monocytogenes can cause disease in humans and in a wide range of animal species, especially in farm ruminants. The aim of the study was to determine the prevalence and genetic diversity of L. monocytogenes related to 1185 cattle abortion cases in Latvia during 2013–2018. The prevalence of L. monocytogenes among cattle abortions was 16.1% (191/1185). The seasonality of L. monocytogenes abortions was observed with significantly higher occurrence (p &lt, 0.01) in spring (March–May). In 61.0% of the cases, the affected cattle were under four years of age. L. monocytogenes abortions were observed during the third (64.6%) and second (33.3%) trimesters of gestation. Overall, 27 different sequence types (ST) were detected, and four of them, ST29 (clonal complex, CC29), ST37 (CC37), ST451 (CC11) and ST7 (CC7), covered more than half of the L. monocytogenes isolates. Key virulence factors like the prfA-dependent virulence cluster and inlA, inlB were observed in all the analyzed isolates, but lntA, inlF, inlJ, vip were associated with individual sequence types. Our results confirmed that L. monocytogenes is the most important causative agent of cattle abortions in Latvia and more than 20 different STs were observed in L. monocytogenes abortions in cattle.

Background Campylobacter is the main cause of bacterial gastroenteritis worldwide. The main transmission route is through consumption of food contaminated with Campylobacter species or contact with infected animals. In Latvia, the prevalence of campylobacteriosis is reported to be low (4.6 cases per 100,000 population in 2016). Aim To determine prevalence, species spectrum and antimicrobial resistance (AMR) of Campylobacter spp. in Latvia, using data from various livestock and human clinical samples. Methods We analysed data of Campylobacter microbiological monitoring and AMR (2008 and 2014–16) in Latvia. Data from broilers, poultry, pigs, calves and humans were used to determine prevalence of Campylobacter. Additionally, 45 different origin isolates (22 human) were sequenced on the Illumina MiSeq platform; for each isolate core genome multilocus sequence typing was used and relevant antimicrobial resistance mechanisms were identified. Results Overall, Campylobacter prevalence in was 83.3% in pigs, 50.2% in broilers, 16.1% in calves and 5.3% in humans; C. jejuni was the predominant species in all sources except pigs where C. coli was main species. High level of resistance in Campylobacter were observed against fluoroquinolones, tetracycline and streptomycin, in most of sequenced isolates genetic determinants of relevant AMR profiles were identified. Conclusions In Latvia, prevalence of Campylobacter in livestock is high, especially in pigs and broilers; prevalence in poultry and humans were lower than in other European countries. AMR analysis reveals increase of streptomycin and tetracycline resistant broiler origin C. jejuni strains. WGS demonstrates a high compliance between resistance phenotype and genotype for quinolones and tetracyclines.