These cross-sectional studies reported the occurrence, genetic characteristics, and factors associated with the distribution of Listeria species on cattle farms and beef abattoirs in Gauteng Province, South Africa. A total of 328 samples (faeces, feeds, silage, and drinking water) were collected from 23 cattle farms (communal, cow-calf, and feedlot), and 262 samples (faeces, carcass swabs, and effluents) from 8 beef abattoirs (low throughput and high throughput) were processed using standard bacteriological and molecular methods to detect Listeria species. The factors associated with the prevalence of Listeria species were investigated, and multiplex polymerase chain reaction (mPCR) was used to determine Listeria species, the pathogenic serogroups, and the carriage of eight virulence-associated genes by Listeria monocytogenes. The overall prevalence of Listeria species in cattle farms was 14.6%, comprising Listeria innocua (11.3%), Listeria monocytogenes (3.4%), Listeria welshimeri (0.0%) compared with 11.1%, comprising Listeria innocua (5.7%), Listeria monocytogenes (4.6%), Listeria welshimeri (0.8%) for beef abattoirs. Of the three variables (area, type of farm/abattoir, and sample type) investigated, only the sample types at abattoirs had a significant (P < 0.001) effect on the prevalence of L. innocua and L. welshimeri. The frequency of distribution of the serogroups based on 11 L. monocytogenes isolated from farms was 72.7% and 27.3% for the serogroup 1/2a-3a and 4b-4d-4e, respectively, while for the 12 L. monocytogenes isolates recovered from abattoirs, it was 25%, 8.3%, 50% and 16.7% for the serogroup 1/2a-3a, 1/2b-3b, 1/2c-3c, and 4b-4d-4e respectively (P < 0.05). All (100%) isolates of L. monocytogenes from the farms and abattoirs were positive for seven virulence genes (hlyA, inlB, plcA, iap, inlA, inlC, and inlJ). The clinical and food safety significance of the findings cannot be ignored.

Listeria monocytogenes is an opportunistic foodborne pathogen. It can resist stress conditions by adapting through the production of biofilms, which represents a serious problem for the food industry. It is classified into 14 serotypes, although only four (1/2a, 1/2b, 1/2c, and 4b) account for 89.0-98.0% of listeriosis cases worldwide. The objective of this study was to detect and serotype L.monocytogenes isolated from different food matrices from processing plants in Argentina. In the period 2016-2021, 1832 samples (meat, ready-to-eat foods, ice cream, dairy foods, and frozen vegetables) were analyzed, of which 226 (12.34%) isolates compatible with L.monocytogenes were detected. At the same time, environmental and surface samplings were performed in processing plants for ready-to-eat foods, sausages and dairy products, where environmental contamination with L.monocytogenes was detected in numerous critical points of the process, yielding a positivity rate of 22.7%. The molecular analysis of serogroups was performed, where it was observed that serogroup IIb was the most frequent with 66.5% (n=107), and in descending order IIc with 22.3% (n=36), and IIa (n=9) and IVb (n=9) with 5.6%. The serogroup mostly isolated in environmental monitoring was IIb. This work highlights the importance of the detection and serotyping of L.monocytogenes for taking actionable measures and identifying outbreaks, and is the first study in Argentina to describe an extensive study in food matrices.

An outbreak of meningococcal disease with a case-fatality rate of 30% and caused by predominantly serogroup W of Neisseria meningitidis began in Chile in 2012. This outbreak required a case-control study to assess determinants and risk factors for infection. We identified confirmed cases during January 2012-March 2013 and selected controls by random sampling of the population, matched for age and sex, resulting in 135 case-patients and 618 controls. Sociodemographic variables, habits, and previous illnesses were studied. Analyses yielded adjusted odds ratios as estimators of the probability of disease development. Results indicated that conditions of social vulnerability, such as low income and overcrowding, as well as familial history of this disease and clinical histories, especially chronic diseases and hospitalization for respiratory conditions, increased the probability of illness. Findings should contribute to direction of intersectoral public policies toward a highly vulnerable social group to enable them to improve their living conditions and health.