Genomic and Antimicrobial Surveillance of Campylobacter Population in Italian Poultry.

Campylobacter is one of the most common foodborne diseases worldwide with increasing rates of antibiotic resistance. Most cases of campylobacteriosis can be traced back to the consumption of poultry meat. Despite many efforts to reduce contamination in farms and in slaughterhouses, the persistence of this pathogen in poultry products remains a problem. This study aimed to evaluate the genetic diversity and antibiotic resistance of 542 C. jejuni and C. coli in Italian poultry, in the framework of two National Monitoring Programs. Genomes were screened for antibiotic resistance, virulence determinants and contextualized within a global collection of C. jejuni. ST2116, ST2863 and ST 832 were the most prevalent and significantly associated with Italian poultry. A worrying increase in resistance to quinolones, fluoroquinolones and tetracycline was observed in C. jejuni, while an increased occurrence of multidrug resistant (MDR) strains and strains resistant to macrolides was detected in C. coli. Low resistance rates were found for aminoglycosides. Molecular resistance determinants were consistent with the phenotypic resistance for tetracycline and quinolones. In silico analysis revealed 119 genes associated with virulence factors, with a notably higher prevalence of some genes in ST2863 genomes. This study highlights the increased resistance to macrolides and the emergence of MDR strains for C. coli, the genetic basis of AMR and the predominance of two genotypes among Campylobacter strains isolated from the Italian poultry farms.

Genetic diversity of Listeria monocytogenes strains contaminating food and food producing environment as single based sample in Italy (retrospective study).

Human listeriosis outbreaks are often associated with food products, which could be contaminated, at the same time, also by different clones of Listeria monocytogenes. This emphasize the need to type more than one L.monocytogenes isolate found in a single food or environmental sample. The purpose of the present study was to evaluate the presence of different L.monocytogenes strains in food and food production environment in order to understand if there is need to type more isolates from the same sample in case of presence of L.monocytogenes. Between 2011 and 2015, at the Italian National Reference Laboratory for L.monocytogenes, for each positive sample, from two to twenty-three isolates of L.monocytogenes were collected. All the isolates were characterized by conventional serotyping and pulsed field gel electrophoresis (PFGE). Moreover, isolates from the same sample, having indistinguishable PFGE profile, were subjected to whole genome sequencing in order to perform core genome Multi Locus Sequence Typing (cgMLST). Within each sample, more than one serotype and one pulsotype were found in 11.9% and 27.5%, respectively. For indistinguishable PFGE patterns the cgMLST analysis showed 96.2% of concordance demonstrating the added value of new sequencing technologies. This study has demonstrated the need to select and type more than one L.monocytogenes colony in one food or food environmental sample to detect the diversity of L.monocytogenes strains and facilitate downstream investigations and effective source attribution in foodborne outbreak inquiry.

Survival rate of Escherichia coli O157 in artificially contaminated raw and thermized ewe milk in different Pecorino cheese production processes.

Pecorino is a typical Italian cheese, mostly produced in central and southern Italy regions using ewe raw milk and following traditional procedures. The use of raw milk constitutes a risk linked to the potential survival or multiplication of pathogenic microorganisms, as Shiga toxin-producing Escherichia coli (STEC). The aim of this study was to compare different Italian traditional Pecorino production methods to determine if there were any phases that could influence the Escherichia coli O157 survival rate, but also if they could negatively influence lactic acid bacteria survival rate, during the phases of production and ripening. Therefore batches of Pecorino cheese were prepared using different production methods, representing the real and typical cheese production in southern and central Italy regions: 1) heating the milk at 37 °C for about 40 min before curding, 2) heating the milk at 60 °C (thermization) for 13 min, so that the alkaline phosphatase reaction is still positive before curding, 3) cooking curd at 41 °C and 4) at 45 °C, both for 5 min. Our results demonstrated that traditional milk treatments different from pasteurization can help but do not eliminate serious microbiological treats, as E. coli O157, especially if the raw milk is heavily contaminated. The heat treatment at 60 °C applied to raw milk was able to decrease the concentration of E. coli O157 of 1.7 log10CFU/ml and, according to the inactivation slope, it would be further reduced prolonging the heating treatment. The results obtained also showed that, during the Pecorino cheese ripening, E. coli O157 was always enumerable for 60 days, remaining detectable after 90 days of ripening.

Characterization of Salmonella Typhimurium and monophasic Salmonella Typhimurium isolated in Abruzzo and Molise regions, Italy, from 2012 to 2017.

Salmonellosis is currently the second most common zoonosis in European Union but in the 6-years periods, between 2012 and 2017, there has been a significant decrease trend in the yearly number of infections caused by Salmonella. In Italy, S. Typhimurium and monophasic S. Typhimurium represent the most prevalent serotypes. In this paper, we investigated these two serovars isolated from 2012 to 2017 in Abruzzo and Molise regions. A set of 345 strains isolated from human sporadic cases, surface water, food and animals were collected and analyzed. Monophasic S. Typhimurium strains were found to be resistant to streptomycin, sulfisoxazole, ampicillin, tetracycline and nalidixic acid, while S. Typhimurium isolates showed high levels of resistance to tetracycline, sulfisoxazole and ampicillin. The 5-loci Multilocus Variable-Number Tandem Repeat Analysis (MLVA) identified 88 genotypes (GT), six of which were common for the two serovars. Several MLVA profiles were shared by human and non-human isolates. MLVA had sufficient typing resolution for epidemiological studies of S. Typhimurium but demonstrated poor discriminatory in trace-back study of monophasic S. Typhimurium.

The prevalence, characterisation, and antimicrobial resistance of Yersinia enterocolitica in pigs from Central Italy.

Widely spread in nature, Yersinia enterocolitica (YE) is a foodborne pathogen of major health and economic significance in developed countries. The aim of this study is to analyse YE strains isolated from 400 slaughtered pigs from the Abruzzo region, Italy, using biochemical tests and a multiplex polymerase chain reaction PCR detecting 6 chromosomal genes (ystA, irp2, 16s, ail, inv, hemR) and one plasmid-borne virulence gene (yadA). Antimicrobial susceptibility was evaluated and pulsed-field gel electrophoresis (PFGE) was also performed in order to assess phylogenetic diversity. In total, 56 samples of porcine tonsils (14%) were found to be positive for the presence of pathogenic YE. All YE belonged to the pathogenic bioserotype 4/O:3. All YE samples were positive for the chromosomal virulence genes ystA, ail, and inv, whereas results for the presence of yadA and hemR were variable. This study found that YE isolates were resistant to ampicillin (100%), streptomycin (26.79%), sulfisoxazole (19.65%), tetracycline (16.08%), nalidixic acid (14.30%), and chloramphenicol (10.72%). The strains characterised by PFGE showed a high similarity. This study demonstrates the usefulness of multiplex polymerase chain reaction (PCR) compared with conventional phenotypic assays for the identification of pathogenic YE isolates and the limitations of PFGE for the molecular typing of YE bioserotype 4/O:3.

Detection and characterisation of potentially pathogenic species of Vibrio in the Vibrata river, Abruzzo Region, Italy.

This study aimed to isolate, define the genetic profile, assess potential pathogenicity and evaluate the seasonal distribution of Vibrio cholerae, Vibrio parahaemolyticus, and Vibrio vulnificus strains isolated from the Vibrata river (Abruzzo Region, Italy) during a monitoring period of one year. Detection was performed according to ISO/TS 21872-1-2:2007. Species identification and characterisation were achieved using molecular methods. Vibrio spp. were detected in 50% (23) of the water samples. In particular, V. cholerae, V. parahaemolyticus, and V. vulnificus were isolated in 18 (39.1%), 4 (8.7%), and 2 (4.3%) samples, respectively. All V. parahaemolyticus strains were tdh gene negative, 75% were positive for trh gene. In 30 V. cholerae isolates, the polymerase chain reaction (PCR) assay for detecting virulence and regulatory genes (ctxA, toxR, tcpA, ompU, hlyA, tcpI, zot, and stn/sto) revealed 6 genotypes associated to different levels of pathogenicity. Pulsed-field gel electrophoresis (PFGE) characterisation of the V. cholerae strains identified 13 different pulsotypes. A greater degree of similarity was shown for strains isolated in the same period of the year. Results of our study reveal a potential health risk associated with the waters of the Vibrata river, which are used for irrigation and next to the swimming areas of Abruzzo coastline.

Model proficiency testing scheme for serological diagnosis of Brucellosis: interlaboratory study.

A model interlaboratory testing scheme was developed by the Italian National Reference Laboratory for Brucellosis. This scheme was planned for both qualitative (Rose Bengal Plate Test; RBPT) and quantitative (Complement Fixation Test; CFT) serological tests and involved a total of 42 laboratories. In the preparation of this scheme, reference was made to general protocols and guidelines and to methods reported in the literature, which were applicable to analytical chemistry laboratories. Six field sera from naturally infected animals, one positive serum at a titer below the European Union (EU) positivity threshold, and 5 sera positive at titers between 20 and 851 International Units of Complement Fixation Test (IUCFT)/mL plus one negative serum were used to produce a panel of test sera. To evaluate laboratory performances in the quantitative test for each tested sample examined, z-scores based on robust summary statistics (the median and normalized interquartile range) were used. To evaluate overall laboratory performance, 2 types of combined z-scores were used: Rescaled Sum of Scores and Sum of Squared Scores. In the case of the qualitative test (RBPT), results were analyzed by a Bayesian approach. A Beta distribution, based on the result of each laboratory, was calculated and used to estimate the probability of each laboratory giving a correct result and its uncertainty.