Uncommon Salmonella Infantis Variants with Incomplete Antigenic Formula in the Poultry Food Chain, Italy.

Uncommon Salmonella Infantis variants displaying only flagellar antigens phenotypically showed identical incomplete antigenic formula but differed by molecular serotyping. Although most formed rough colonies, all shared antimicrobial resistances and the presence of usg gene with wild-type Salmonella Infantis. Moreover, they were undistinguishable wild-type Salmonella Infantis by whole-genome sequencing.

Monophasic Variant of Salmonella Typhimurium 4,[5],12:i:- (ACSSuGmTmpSxt Type) Outbreak in Central Italy Linked to the Consumption of a Roasted Pork Product (Porchetta).

The monophasic variant of S. Typhimurium 4,[5],12:i:- (MVST) is the third most commonly reported Salmonella serovar involved in human infections (8.8%) in the EU and ranks after S. Enteritidis (54.6%) and S. Typhimurium (11.4%). In Italy, in contrast, the MVST has achieved peculiar epidemiological and ecological success which has allowed it to be, since 2011, the serovar most frequently isolated from humans. In the summer of 2022, a foodborne outbreak of the MVST involving 63 people occurred in the Marche Region (Central Italy). A common food exposure source among some human cases was a roasted, ready-to-eat (RTE) pork product, porchetta, which is a typical product of Central Italy. This paper describes the results of investigations conducted to clarify this outbreak. The porchetta was produced by a local manufacturing plant and distributed to at least two local retail stores, one of which was the retail outlet for the manufacturing plant. The MVST was isolated from surface samples collected at the porchetta manufacturing plant and at both local retail stores via bacterial analysis, and the porchetta sampled at one store contained the MVST. These data confirm this type of RTE pork product can be a source of Salmonella infection in humans.

A multi-center validation study on the discrimination of Legionella pneumophila sg.1, Legionella pneumophila sg. 2-15 and Legionella non-pneumophila isolates from water by FT-IR spectroscopy.

This study developed and validated a method, based on the coupling of Fourier-transform infrared spectroscopy (FT-IR) and machine learning, for the automated serotyping of Legionella pneumophila serogroup 1, Legionella pneumophila serogroups 2-15 as well as their successful discrimination from Legionella non-pneumophila. As Legionella presents significant intra- and inter-species heterogeneities, careful data validation strategies were applied to minimize late-stage performance variations of the method across a large microbial population. A total of 244 isolates were analyzed. In details, the method was validated with a multi-centric approach with isolates from Italian thermal and drinking water (n = 82) as well as with samples from German, Italian, French, and British collections (n = 162). Specifically, robustness of the method was verified over the time-span of 1 year with multiple operators and two different FT-IR instruments located in Italy and Germany. Moreover, different production procedures for the solid culture medium (in-house or commercial) and different culture conditions (with and without 2.5% CO2) were tested. The method achieved an overall accuracy of 100, 98.5, and 93.9% on the Italian test set of Legionella, an independent batch of Legionella from multiple European culture collections, and an extra set of rare Legionella non-pneumophila, respectively.

Whole-Genome Sequence of Salmonella enterica Serovar Bispebjerg from Turkey Reveals Its Pathogenic Potential.

We report the genome sequence of a Salmonella enterica subsp. enterica serovar Bispebjerg strain that was isolated from a turkey flock in 2011. The genome analysis of the strain, a rare and multihost serovar, revealed its pathogenic potential due to antimicrobial resistance and a plethora of Salmonella pathogenicity islands and virulence factors.

A Strong Evidence Outbreak of Salmonella Enteritidis in Central Italy Linked to the Consumption of Contaminated Raw Sheep Milk Cheese.

Salmonellosis is the second most commonly reported gastrointestinal infection in humans after campylobacteriosis, and an important cause of foodborne outbreaks in the EU/EEA. The vast majority (72.4%) of the salmonellosis foodborne outbreaks reported in EU in 2019 were caused by Salmonella Enteritidis, even if their total number due to this serovar decreased. In spring 2020, a foodborne outbreak of S. Enteritidis occurred in the Marche region (Central Italy), involving 85 people. The common exposure source was a cheese, pecorino "primo sale", produced with raw sheep milk. The cheese batches were produced by two local dairies, with a livestock production facility, also including a sheep farm, being part of one dairy. Bacteriological analysis of samples collected allowed the detection of S. Enteritidis in animal faeces, environmental samples, raw-milk bulk tanks and milk taken from single animals. These data confirm that, despite the scarce scientific evidence, S. Enteritidis can infect sheep and be shed into the animals' milk. Hence, this is a real risk for public health when unpasteurized milk is used in production of such cheese. The present paper describes the results of the investigations conducted to clarify this outbreak.

The Interplay between Campylobacter and the Caecal Microbial Community of Commercial Broiler Chickens over Time.

Campylobacter is the most frequent foodborne zoonotic bacteria worldwide, with chicken meat being overwhelmingly the most important reservoir for human infections. Control measures implemented at the farm level (i.e., biosecurity or vaccination), which have been successfully applied to limit other pathogens, such as Salmonella, have not been effective in reducing Campylobacter occurrence. Thus, new approaches are needed to fully understand the ecological interactions of Campylobacter with host animals to effectively comprehend its epidemiology. The objective of this study was to analyse longitudinally the gut microbiota composition of Campylobacter-infected and non-infected farms to identify any difference that could potentially be indicative of gut colonization by Campylobacter spp. Differences in the colonization rate and timing were observed at the farms that became positive for Campylobacter jejuni over the investigated time points, even though in positive tests, the occurrence of Campylobacter jejuni gut colonization was not observed before the second week of the life of the birds. Significant differences were observed in the abundances of specific bacterial taxa between the microbiota of individuals belonging to farms that became Campylobacter positive during the study and those who remained negative with particular reference to Bacteroidales and Clostridiales, respectively. Moreover, Campylobacter colonization dramatically influenced the microbiota richness, although to a different extent depending on the infection timing. Finally, a key role of Faecalibacterium and Lactobacillus genera on the Campylobacter microbial network was observed. Understanding the ecology of the Campylobacter interaction with host microbiota during infection could support novel approaches for broiler microbial barrier restoration. Therefore, evidence obtained through this study can be used to identify options to reduce the incidence of infection at a primary production level based on the targeted influence of the intestinal microbiota, thus helping develop new control strategies in order to mitigate the risk of human exposure to Campylobacter by chicken meat consumption.

Genome Sequence of a Persistent Campylobacter jejuni Strain, 2016-IZSVE-19-111250.

In this report, we present the whole-genome sequence of a Campylobacter jejuni strain isolated recursively for the last 3 years from an Italian poultry farm.

Characterizing Salmonella enterica Serovar Choleraesuis, var. Kunzendorf: A Comparative Case Study.

Different Salmonella serovars generally display different antigenic formulae, but there are some exceptions. For instance, the same antigenic formula, 6,7:c:1,5, is shared by Salmonella enterica serovar, Paratyphi C, Typhisuis, and Choleraesuis. Moreover, three biotypes have been described within the S. Choleraesuis serovar. A distinction among such biotypes can only be based on biochemical behaviors (biotyping) posing serious concerns when rapid characterization is required. The study of an outbreak of severe epizootic salmonellosis in wild boars occurred in Italy between 2012 and 2014 and the typing of the isolates recovered from the outbreak were used to test different approaches for serovar identification. A number of 30 S. Choleraesuis var. Kunzendorf isolates from the outbreak were typed by means of four different methods to derive serovar and biotype: (i) slide agglutination method followed by biochemical tests, (ii) suspension array xMAP® Salmonella Serotyping Assay (SSA), (iii) whole genome sequencing (WGS) and data analysis using SeqSero tool, and (iv) WGS and data analysis using Salmonella TypeFinder tool. Slide agglutination, xMAP® SSA and WGS, followed by SeqSero analysis, are methods that infer the serovars according to the White-Kauffmann-Le Minor (WKL) scheme, based exclusively on antigens. Using these methods, isolates with incomplete antigenic formulae could be misleadingly excluded from an outbreak. On the contrary, WGS followed by Salmonella TypeFinder data analysis, which predicts the serotype on the basis of Multilocus sequence typing (MLST), might be able to cluster together isolates belonging to the same outbreak irrespective of the antigenic formula. Results suggest the benefit of routine use of a combination of in silico MLST and antigenic formula analysis to solve specific ambiguous case studies for outbreak investigation purposes.

Evaluation and quantification of antimicrobial residues and antimicrobial resistance genes in two Italian swine farms.

Antimicrobial resistance genes (ARGs) are considered emerging environmental pollutants, posing potential risks for human and animal health: the misuse of antimicrobials in food-producing animals could favour the maintenance and spread of resistances in bacteria. The occurrence of ARGs in Italian swine farming - which has specific characteristics - was investigated in order to explore resistance spread dynamics. Two farrow-to-finish pig farms were longitudinally monitored: faecal samples from animals and environmental samples were collected. DNA was extracted and tetA, ermB, qnrS and mcr1 ARGs were analysed by qPCR for their ability to confer resistance to highly or critically important antimicrobials (CIAs). Moreover, 16SrDNA gene was analysed to assess bacterial abundance. ermB and tetA genes were found in animal samples and manure samples. On the contrary, mcr1 was exclusively found in weaners, while qnrS occurred in all animal categories but sows and finishers. Among the analysed genes, ermB and tetA showed the highest absolute and relative abundances. Our results indicate that ermB and tetA ARGs are widely disseminated in the explored farms, suggesting efficient maintenance among bacteria and persistence in the environment. Interestingly, the presence of qnrS and mcr1, limited to just a few animal categories, highlights inefficient dissemination of these genes in the farm environment, in particular for mcr1, a stable plasmid gene conferring resistance to the last-resort antimicrobial, colistin. Paying close attention only to the finishing phase would have hampered the discovery of resistances to CIAs at farm level, which we instead identified thanks to an intensive longitudinal monitoring programme.