Antimicrobial Resistance and Genomic Characterization of Salmonella Infantis from Different Sources.

The epidemiology of Salmonella Infantis is complex in terms of its distribution and transmission. The continuous collection and analysis of updated data on the prevalence and antimicrobic resistance are essential. The present work aimed to investigate the antimicrobial resistance and the correlation among S. Infantis isolates from different sources through the multiple-locus variable-number of tandem repeat (VNTR) analysis (MLVA). A total of 562 Salmonella strains isolated from 2018 to 2020 from poultry, humans, swine, water buffalo, mussels, cattle, and wild boar were serotyped, and 185 S. Infantis strains (32.92%) were identified. S. Infantis was commonly isolated in poultry and, to a lesser extent, in other sources. The isolates were tested against 12 antimicrobials, and a high prevalence of resistant strains was recorded. S. Infantis showed high resistance against fluoroquinolones, ampicillin, and tetracycline, which are commonly used in human and veterinary medicine. From all S. Infantis isolates, five VNTR loci were amplified. The use of MLVA was not sufficient to understand the complexity of the epidemiological relationships between S. Infantis strains. In conclusion, an alternative methodology to investigate genetic similarities and differences among S. Infantis strains is needed.

Assessment of food microbiological indicators applied on poultry carcasses by culture combined MALDI-TOF MS identification and 16S rRNA amplicon sequencing.

Examination of the bacterial contamination on food products is still largely performed by standardized culture methods, though culture-independent methods are suggested as a more reliable approach. Knowledge of the diversity of bacteria isolated from food as well as the impact of the plate incubation conditions applied are still understudied. The impact of incubation at 7 °C and 30 °C on total aerobic bacterial count and diversity, and the performance of ISO methods generally applied in microbiological quality examination were assessed by culture combined MALDI-TOF MS identification and 16S rRNA amplicon sequencing. Examining breast skin of 16 chicken carcasses, no significant impact of the incubation temperature on the total aerobic bacteria level and diversity was detected, limiting the usefulness of additional psychrophilic examination. Bacteria phenotypically similar to Pseudomonas, were identified on selective CFC plates, and on MRS agar plates for lactic acid bacteria, Escherichia coli and Staphylococcus were commonly present. Application of 16S rRNA amplicon sequencing revealed a higher bacterial diversity, but the impact of the DNA extraction kit applied, and the detection of non-viable bacteria should be taken into account to interpret the final outcome.

Evaluation of virulence genes in Yersinia enterocolitica strains using SYBR Green real-time PCR.

Yersinia enterocolitica comprises six biotypes 1A, 1B, 2, 3, 4, and 5. The virulence of the strains belonging to biotypes 1B and 2-5 depends on the presence of both chromosomal and plasmid-borne genes. Strains belonging to biotype 1A do not carry the virulence plasmid pYV. However, they carry other virulence genes, such as ystB and hreP. The aim of this study was to investigate the distribution of yadA, virF, inv, ystA, ystB, myfA, hreP and ymoA virulence genes in Y. enterocolitica strains in order to select the target genes that could be used for the development of a probe-specific real-time PCR to determine the presence of Y. enterocolitica in food samples. A total of 161 Y. enterocolitica strains isolated in eight countries and grouped into biotypes 1A, 2 (serotypes O3, O5 and O9), 3 (serotypes O3 and O9) and 4 (serotype O3) were examined for virulence genes. The most common virulence-associated gene in pathogenic Y. enterocolitica proved to be ystA, which can therefore be considered the best target gene to be amplified in order to evaluate the presence of pathogenic biotypes. By contrast, to identify Y. enterocolitica 1A strains, ystB, which codes for the enterotoxin YstB, can be proposed. This has been found in all non-pathogenic biotypes studied, but never in pathogenic biotypes.

Antimicrobial Resistance of Listeria monocytogenes Strains Isolated in Food and Food-Processing Environments in Italy.

Listeria monocytogenes, along with various other pathogenic bacteria, may show resistance against a broad spectrum of antibiotics. Evaluating the extent of resistance in harmful microorganisms like Listeria monocytogenes holds significant importance in crafting novel therapeutic strategies to mitigate or combat the rise of infections stemming from antibiotic-resistant bacteria. The present work aims to investigate the occurrence of antimicrobial resistance among Listeria monocytogenes strains in meat products (n = 173), seafood (n = 54), dairy products (n = 19), sauces (n = 2), confectionary products (n = 1), ready-to-eat rice dishes (n = 1), and food-processing environments (n = 19). A total of 269 Listeria monocytogenes strains belonging to eight different serovars were tested against 10 antimicrobials. In the classes of antibiotics, most of the strains were resistant antibiotics belonging to the family of ß-lactams (92.94%). High proportions of L. monocytogenes isolates were resistant to oxacillin (88.48%), followed by fosfomycin (85.87%) and flumenique (78.44%). The lowest level of resistance was observed against gentamycin (1.49%). A total of 235 strains (n = 87.36%) showed a profile of multidrug resistance. In conclusion, a high occurrence of resistant and multidrug-resistant strains of Listeria monocytogenes was observed among the examined serotypes isolated from different food sources. This understanding enables the adoption of suitable measures to avert contamination and the spread of resistant bacteria via food.

Detection of pathogenic Vibrio spp. in foods: polymerase chain reaction-based screening strategy to rapidly detect pathogenic Vibrio parahaemolyticus, Vibrio cholerae, and Vibrio vulnificus in bivalve mollusks and preliminary results.

The majority of human diseases attributed to seafood are caused by Vibrio spp., and the most commonly reported species are Vibrio parahaemolyticus, Vibrio vulnificus, and Vibrio cholerae. The conventional methods for the detection of Vibrio species involve the use of selective media, which are inexpensive and simple but time-consuming. The present work aimed to develop a rapid method based on the use of multiplex real-time polymerase chain reaction (PCR) to detect V. parahaemolyticus, V. vulnificus, and V. cholerae in bivalve mollusks. 30 aliquots of bivalve mollusks (Mytilus galloprovincialis) were experimentally inoculated with two levels of V. parahaemolyticus, V. vulnificus, and V. cholerae. ISO 21872-1:2017 was used in parallel for qualitative analysis. The limit of detection of 50% was 7.67 CFU/g for V. cholerae, 0.024 CFU/g for V. vulnificus, and 1.36 CFU/g for V. parahaemolyticus. For V. vulnificus and V. cholerae, the real-time PCR protocol was demonstrated to amplify the pathogens in samples seeded with the lowest and highest levels. The molecular method evaluated showed a concordance rate of 100% with the reference microbiological method. V. parahaemolyticus was never detected in samples contaminated with the lowest level, and it was detected in 14 samples (93.33%) seeded with the highest concentration. In conclusion, the developed multiplex real-time PCR proved to be reliable for V. vulnificus and V. cholerae. Results for V. parahaemolyticus are promising, but further analysis is needed. The proposed method could represent a quick monitoring tool and, if used, would allow the implementation of food safety.

Occurrence and distribution of Salmonella serovars associated with human infection isolated from irrigation waters and food-producing animals in southern Italy: eleven-year monitoring (2011-2021).

Salmonella is one of the main zoonotic agents causing foodborne diseases in Europe. The main reservoirs of the infection are represented by domestic and wild animals, and the infection occurs by direct contact or following the consumption of contaminated food or water. The study aimed to evaluate the presence of Salmonella spp. in food-producing animals and irrigation waters in southern Italy and the serovar distribution. From 2011 to 2021, a total of 473 samples from 6 different animal species (bovine, buffalo, goat, ovine, swine, poultry, and wild boars) and 313 irrigation water samples were collected and analyzed. The overall percentage of positive samples was 56.87% in organs, 50.85% in feces, and 20.45% in irrigation waters. By animal species, the most frequently detected serovar was Salmonella Typhimurium in bovine (17.39%), in buffalo (13.10%) and swine (28.21%), and S. Kentucky (24.78%) in poultry. The subspecies diarizonaeIIIb was frequently detected in goats (40.00%) and ovine (83.33%), while salamaeII (14.12%) and diarizonaeIIIb (11.76%) were frequently isolated in wild boars. In the irrigation water samples, the most frequently detected serovar was S. Napoli (25%). Results revealed that, although in Europe, control strategies aimed at preventing the spread of Salmonella have been implemented, the prevalence of this pathogen in food-producing animals and irrigation waters is high. Considering the risk to public health associated with the contamination of products or foods, more stringent control interventions are needed at primary production and along the food chain.

Examining the Veterinary Electronic Antimicrobial Prescriptions for Dogs and Cats in the Campania Region, Italy: Corrective Strategies Are Imperative.

Companion animals are increasingly being recognised as important contributors to the spread of antimicrobial-resistant bacteria. The present work aimed to measure the antimicrobial drug prescribing in dogs and cats in the Campania Region, Italy by analysing the Veterinary Electronic Prescriptions (VEPs) between 2019 and 2020. The medical records associated with antimicrobial drug prescriptions were collected according to the drug administration (systemic or topical) and the rationale for the treatment chosen. In the period under investigation, 166,879 drugs were prescribed of which 129,116 (73.4%) were antimicrobial. A total of 83,965 (65%) antibiotics were prescribed to dogs, 40,477 (31.4%) to cats, and 4674 (3.6%) to other companion animals. In dogs, 90.5% of VEPs prescribed for systemic treatment included an antimicrobial Critically Important or Highly Important or Important for human medicine (WHO, 2018). The most widely prescribed class was fluoroquinolones. The antimicrobials prescribed were mainly metronidazole-spiramycin (29.7%), amoxicillin-clavulanic (19.6%), enrofloxacin and cephalexin in dogs (16.5%) and enrofloxacin (22.6%) and amoxicillin-clavulanic acid (21.4%) in cats. Based on the results, the widespread use of broad-spectrum antimicrobials and the use of molecules for which limitations should be observed according to the EMA guidelines has emerged.

Wild boars as reservoir for Campylobacter and Arcobacter.

Campylobacteriosis is a significant public health concern with Campylobacter jejuni and Campylobacter coli as main causative agents. Moreover, there is an increasing recognition of other pathogenic Campylobacter species and Campylobacter-like organisms as Arcobacter. However, current knowledge on presence of Arcobacter species in wild boars (Sus scrofa) is lacking, and knowledge on Campylobacter species is based on methods favoring growth of thermotolerant species. In this study, fecal samples originating from 76 wild boars hunted in Campania region (Italy) were examined for the presence of Campylobacter(-like) organisms by a culture dependent approach. Three isolation protocols were performed in parallel: Arcobacter-selective agar plates, mCCDA plates and isolation by passive filtration onto non-selective blood agar plates were used as quantitative isolation methods. Enrichment broths, i.e. Arcobacter selective enrichment broth, Preston broth and CAT broth were used for qualitative detection of low levels or stressed Campylobacter(-like) organisms. The Arcobacter and Campylobacter isolates were identified at species level using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and 16S ribosomal RNA (rRNA) sequence analysis. Overall, 41 (53.9%) of the animals excreted Arcobacter or Campylobacter while 38 (50.0%) shed Campylobacter and 8 (10.5%) Arcobacter. Campylobacter lanienae predominated and was isolated from 31 (40.8%) animals. No statistical difference between the age groups or gender with regard to the fecal excretion of Campylobacter(-like) organisms was observed. Thirty animals (39.5%) shed Campylobacter spp. exceeding levels of 10 ³ CFU g-1 feces. As samples were obtained from hunted wild boars intended for consumption, a potential contamination of meat with these bacterial pathogens must be considered.

Late blowing defect in Grottone cheese: detection of clostridia and control strategies.

"Grottone" is a pasta filata hard cheese produced in Campania region from cow's milk and characterized by holes formation due to CO2 development by Propionic Acid Bacteria. The contamination of raw milk with butyric acid-producing spore-forming clostridia represent a major concern for cheese producers since clostridia outgrowth may lead to the cheese late blowing defect during ripening. Detection of clostridial endospores in milk before processing and the use of antimicrobial compounds may represent an important control strategy. The present study is aimed to point out the most suitable procedure for the determination of clostridial spores in dairy samples, and to assess the inhibitory activity of several antimicrobial compounds against Cl. sporogenes. Based on results, MPN counts on Bryant and Burkey medium and CFU on RCM proved to be the most suitable protocols for routine testing. By using these procedures clostridial spores were detected in 10 out 13 milk samples and in all cheeses with late blowing defect. Within antimicrobial compounds, sodium nitrate is still the best choice for preventing late blowing, nevertheless a protective culture of Lacticaseibacillus casei proved to be a promising alternative. Nevertheless, the use of this protective culture in six Grottone cheese productions carried out at farm level, led to unsatisfactory results. Holes' development was hampered likely for an inhibition of the PAB starter and the expected 'Grouviera-type' taste was not perceived by panellists. Based on results, the use of protective cultures needs to be contextualized and interactions with starters needs to be evaluated case by case.

Presence of enteric bacterial pathogens in meat samples of wild boar hunted in Campania region, southern Italy.

Wild boars can be infected with several foodborne pathogens which may be transmitted to humans through the consumption of their meat, but currently, data of their prevalence are still limited. The present study aimed to evaluate the presence of enteric pathogens in wild boar meat samples killed in the Campania region. Twentyeight wild boar meat samples were analyzed for the detection of Salmonella spp, Y. enterocolitica, Campylobacter spp., and Shiga- Toxigenic E. coli. Salmonella spp. was detected and isolated in ten samples and after serotyping S. Veneziana, S. Kasenyi, S. Coeln, S. Manhattan, S. Thompson, and S. Stanleyville were identified. Twenty-one meat samples were found to be contaminated with Y. enterocolitica; in 6 samples the ystA and ystB genes were detected simultaneously, while in 15 only the ystB gene, which characterizes the bacteria belonging to the biotype 1A, was present. Shiga-Toxin producing E. coli was detected in 12 while Campylobacter spp was never detected. In conclusion, due to the high occurrence of pathogenic bacteria detected, the present research shows that wild boars are important reservoirs for foodborne zoonoses which may be transmitted to livestock and humans. This confirms the importance of controls throughout the wild boar supply chain. In the Campania region, checks are guaranteed by the Veterinarians who work within the "management and control plan for wild boar in the Campania region" which has the twofold objective of containing the increasingly invasive presence of this animal and guaranteeing greater safety, traceability, and transparency in the consumption of meat.

Occurrence and distribution of Salmonella serovars in carcasses and foods in southern Italy: Eleven-year monitoring (2011-2021).

Salmonella is one of the most common agents of foodborne illness. The genus Salmonella includes two species (Salmonella bongori and S. enterica) and six subspecies (enterica I, salamae II, arizonae IIIa, diarizonae IIIb, houtenae IV, and indica VI), each of which contains multiple serotypes associated with animal and human infections. The aim of the study was to evaluate the presence of Salmonella spp. in carcasses of food-producing animals and foods in southern Italy and the serovar distribution among different sources. From 2011 to 2021, a total of 12,246 foods and 982 samples from animal carcasses were collected and analyzed. The overall percentage of positive samples was 5.84% (N = 773) and a significant increase in prevalence was observed by comparing the years 2011-2015 (257, 3.27%) and 2016-2021 (516, 9.61%; p < 0.05). The highest percentage of positive food samples was observed in "Meat and Meat Products" (N = 327/2,438, 13.41%) followed by "Fish and fishery products" (N = 115/1,915, 6.01%). In carcasses, the highest percentage of positive samples was reported from broilers (N = 42/81, 51.85%) followed by buffalo (N = 50/101, 49.50%) and pork (N = 140/380, 36.84%). After typing, the isolates were assigned to the species S. enterica and to the subspecies: enterica (N = 760, 98.32%), diarizonae (N = 8, 1.03%), salamae (N = 3, 0.39%) and houtenae (N = 2, 0.26%). S. Infantis was the most frequently detected (N = 177, 24.76%), followed by S. Derby (N = 77, 10.77%), monophasic S. Typhimurium (N = 63, 8.81%), S. Typhimurium (N = 54, 7.55%), and S. Rissen (N = 47, 6.57%). By comparing the sampling period 2011-2015 with that of 2016-2021, an increase in the prevalence of S. Infantis and monophasic S. Typhimurium and a decrease of S. Typhimurium were recorded (p < 0.05). Thus, present data suggest that, despite the implementation of national and European control strategies to protect against Salmonella, the prevalence of this pathogen in southern Italy is still increasing and a change of national control programs to protect against Salmonella are necessary.

Surveillance of Human Cases of Salmonellosis, Campylobacteriosis, Listeriosis, and Hepatitis A in Campania (Southern Italy): Seven-Year Monitoring (2013-2019).

Foodborne infections cause illness and death every year worldwide. The aim of this study was to describe trends in 2013-2019 in the occurrence of human cases of salmonellosis, campylobacteriosis, listeriosis, and hepatitis A in the Campania region. Human case data were provided by the National Surveillance System of disease and were grouped by year, province, age group, and sex. Moreover, the number of people hospitalized was recorded. In the Campania region, the total number of confirmed human cases for the diseases investigated was 1924, with Hepatitis A and the Salmonellosis as the first most reported (1009 and 825 cases, respectively). The incidence rates of gastroenteritis under study were lower than those in Italy and European Union in the same period, with the exception of Hepatitis A whose incidence was higher than that recorded in Italy. Data on hospitalizations pointed out the onset of severe forms of infection also for listeriosis and campylobacteriosis, whose incidence was very low (27 and 63 cases, respectively). Unfortunately, no information on the foods implicated is available. Although probably underestimated, gastroenteritis due to foodborne agents still represents a burden in Campania, and continuous monitoring and implementation of the currently available regional surveillance system is required.

Evaluation of microbial contamination of different pork carcass areas through culture-dependent and independent methods in small-scale slaughterhouses.

Routine evaluation of the slaughter process is performed by the enumeration of the aerobic colony count, Enterobacteriaceae and Salmonella spp. on the carcass through destructive or non-destructive methods. With non-destructive methods, bacteria are counted from a minimum area of 100 cm2 in different sampling sites on the pork carcasses, and the results of these investigated areas are pooled to one value for the complete carcass evaluation (a total of 400 cm2). However, the composition of the bacterial community present on the different sampling areas remains unknown. The aim of the study was to characterize the microbial population present on four areas (ham, back, jowl and belly) of eight pork carcasses belonging to two different slaughterhouses through culture-dependent (Matrix-assisted laser desorption/ionization time-of-flight Mass Spectrometry MALDI-TOF MS, combined with 16S rRNA gene sequencing) and complementary culture-independent (16S rRNA amplicon sequencing) methods. The presence of Salmonella spp. and Y. enterocolitica was additionally assessed. Using MALDI-TOF MS, Staphylococcus, Pseudomonas, and Escherichia coli were found to dominate the bacterial cultures isolated from the 8 carcasses. Based on the 16S rRNA amplicon sequencing analyses however, no specific genus clearly dominated the bacterial community composition. By using this culture-independent method, the most abundant genera in microbial populations of the ham, back, jowl and belly were found to be similar, but important differences between the two slaughterhouses were observed. Thus, present data suggests that the indigenous bacterial population of individual animals is overruled by the microbial population of the slaughterhouse in which the carcass is handled. Also, our data suggests that sampling of only one carcass area by official authorities may be appropriate for the evaluation of the hygienic status of the carcasses and therefore of the slaughter process.

The Influence of Broilers' Body Weight on the Efficiency of Electrical Stunning and Meat Quality under Field Conditions.

Water-bath stunning represents the most-applied stunning system in poultry slaughtering, but within the European Union, specific indications on electric parameters that should be used, such as voltage, are missing. The objective of this study was to evaluate the efficiency of two commercially available types of electrical equipment (A and B) on broilers with different live body weights and the influence of the tested parameters on meat quality. Experimental trials in a European Union-approved slaughterhouse were carried out using two different stunners. 6600 broilers, divided into three weight groups, were stunned applying different protocols based on the same current frequencies and intensity but different voltages. The state of unconsciousness (presence of corneal reflex and wings flapping) and post-mortem defects (pectoral hemorrhages and dark meat) were evaluated by blinded trained operators. The presence of corneal reflex and petechiae were the most reported consciousness signs and post-mortem injuries, respectively. Different weights played an important role within stunner A, registering statistical differences (p < 0.01) among groups. Considering injuries, an inverse relationship between body weight and lesions was found. The results highlighted the effectiveness of both stunning systems applying the best combination of electrical parameters considering the weight of the animal and ensuring its well-being.

Serotyping and Evaluation of Antimicrobial Resistance of Salmonella Strains Detected in Wildlife and Natural Environments in Southern Italy.

Wild animals are potential vectors of antibiotic-resistant bacteria in the environment. The present study aimed to investigate the occurrence of antimicrobial resistance among Salmonella serovars isolated from wildlife and the environment in Italy. A total of 164 Salmonella isolates were analyzed, and six different subspecies and 64 serovars were detected. High proportions of Salmonella isolates proved resistant to streptomycin (34.1%), followed by trimethoprim-sulfamethoxazole (23.2%), tetracycline (17.7%), ciprofloxacin (14.63%) and ampicillin (11.59%). By source, the lowest level of resistance was observed in Salmonella serovars isolated from a water environment, while antimicrobial resistance was frequent in strains collected from shellfish, reptiles and birds. Multidrug-resistant strains were recovered from seafood (n = 11), mammals (n = 3) and water (n = 1). Three S. Typhimurium monophasic variant strains showed asimultaneous resistance to ampicillin, streptomycin, tetracycline and trimethoprim-sulfamethoxazole, which represents a recognized alert resistance profile for this serovar. These data indicate the environmental dissemination of resistant strains due to anthropogenic activities, which, in southern Italy, probably have a higher impact on marine ecosystems than on terrestrial ones. Moreover, as most of the animals considered in the present study are usually consumed by humans, the presence of resistant bacteria in them is a matter of great concern.

Detection and quantification of Campylobacter in foods: New analytic approaches to detect and quantify Campylobacter spp. in food samples.

The aim of the present study was to develop rapid qualitative and quantitative methods based on the use of Real-Time PCR and Droplet Digital PCR (ddPCR), in order to have reliable techniques to detect and quantify Campylobacter spp. in food samples. The gene 16S-rRNA was used as specific target for Campylobacter spp. Real- Time PCR evaluation assay and a not competitive internal control was ushered in it. To investigate the selectivity of the method, 26 Campylobacter strains and 40 non-Campylobacter strains were tested and in order to verify the application of Real- Time PCR method, 5 pork meat samples were experimentally inoculated with a Campylobacter jejuni strain. Subsequently, dilutions with a bacterial load of Campylobacter jejuni within 10-106 CFU/mL were chosen for the optimization of the ddPCR assay. Lastly, a total of 54 naturally contaminated foods samples were analyzed through molecular (Real-Time PCR and ddPCR) and traditional methods. The Real-Time PCR protocol demonstrated to amplify only the Campylobacter spp. strains and when Campylobacter jejuni was experimentally inoculated in meat samples the pathogen was always detected. The ddPCRs assay allowed to quantify a level of contamination of 10 CFU/mL, but it was unable to quantify levels of 105 - 106 CFU/mL. Lastly, Campylobacter spp. was never detected in the 54 samples tested. In conclusion, the novel analytic approach proposed, based on an initial screening of the samples with Real-Time PCR and then on quantification of Campylobacter spp. with a ddPCR on those positive, represents a quick monitoring tool and, if used correctly, it would allow the implementation of food safety.

Exposure to Bacillus cereus in Water Buffalo Mozzarella Cheese.

Bacillus cereus is a spoilage bacterium and is recognized as an agent of food poisoning. Two food-borne illnesses are caused by B. cereus: a diarrheal disease, associated with cytotoxin K, hemolysin BL, non-hemolytic enterotoxin and enterotoxin FM, and an emetic syndrome, associated with the cereulide toxin. Owing to the heat resistance of B. cereus and its ability to grow in milk, this organism should be considered potentially hazardous in dairy products. The present study assessed the risk of B. cereus poisoning due to the consumption of water buffalo mozzarella cheese. A total of 340 samples were analyzed to determine B. cereus counts (ISO 7932:2005); isolates underwent molecular characterization to detect the presence of genes encoding toxins. Eighty-nine (26.1%) samples harbored B. cereus strains, with values ranging from 2.2 × 102 to 2.6 × 106 CFU/g. Isolates showed eight different molecular profiles, and some displayed virulence characteristics. Bacterial counts and the toxin profiles of isolates were evaluated both separately and jointly to assess the risk of enteritis due to B. cereus following the consumption of buffalo mozzarella cheese. In conclusion, the results of the present study showed that the risk of poisoning by B. cereus following the consumption of this cheese was moderate.

Antimicrobial Susceptibility Testing for Salmonella Serovars Isolated from Food Samples: Five-Year Monitoring (2015-2019).

The continuous collection and analysis of updated data on the antimicrobic resistance among bacterial strains represent the essential core for the surveillance of this problem. The present work aimed to investigate the occurrence of antimicrobial resistance among Salmonella serovars isolated in foods in 2015-2019. A total of 178 Salmonella strains belonging to 39 serovars were tested against 10 antimicrobials. High proportions of Salmonella isolates were resistant to tetracycline (n = 53.9%), ciprofloxacin (n = 47.2%), ampicillin (n = 44.4%), nalidixic acid (n = 42.7%), and trimethoprim-sulfamethoxazole (n = 38.8%). Different resistance rates were recorded among the different serotypes of Salmonella, and S. Infantis, exhibited the highest resistance to antibiotics. A high percentage of strains isolated from poultry, pork, and bovine were resistant to at least one or two antimicrobials. Resistant and multidrug-resistant (MDR) strains were also recorded among the isolates from molluscan shellfish; however, the occurrence of resistant Salmonella strains isolated from this source was significantly lower compared with those reported for poultry, pork, and bovine. The high levels of resistance reported in the present study indicate a potential public health risk. Consequently, additional hygiene and antibiotic stewardship practices should be considered for the food industry to prevent the prevalence of Salmonella in foods.

Microbiological, rheological and physical-chemical characteristics of bovine meat subjected to a prolonged ageing period.

The aim of this study was to evaluate the effects of a long ageing period on the microbiological, rheological and physicalchemical characteristics of bovine beef. For the trial n. 3 Marchigiana bovine breed (live weight of 760 kg approximately), slaughtered at 34 months were chosen and the loin muscles were undergone to a prolonged ageing process. The analytical determinations performed were: pH and aw values, texture profile analysis, Warner-Bratzler shear force, colour (CIE L*a*b*), centesimal analysis, total bacterial count, Enterobacteriaceae, Listeria monocytogenes, yeasts and moulds. The results indicate that extended ageing has a negative effect on weight loss but, by the means of the standardization of dry aging parameters, reduce lipid oxidation and improve tenderness.

Characterization of Salmonella Typhimurium and its monophasic variant 1,4, [5],12:i:- isolated from different sources.

In order to characterize the most commonly detected Salmonella serotypes, we tested 124 isolates of S. Typhimurium and 89 isolates of the monophasic variant of S. Typhimurium (S. 1,4, [5],12:i:-) for their antimicrobial susceptibility by means of the Kirby-Bauer disk-diffusion method, and for the detection of 19 genes (four Phage Markers (g13, Sieb, eat, g8), ten prophage-related virulence genes (gipA, gtgB, nanH, gogB, grvA, sopE, sspH1, sspH2, sodC1, gtgE), and five plasmid-borne virulence genes (spvC, pefA, mig5, rcK, srgA)) by means of PCR-based assays. A total of 213 strains were analyzed from, humans (n = 122), animals (n = 25), food (n = 46), and irrigation water (n = 20). S. Typhimurium isolates showed higher variability, in both their resistance profiles and molecular typing, than S. 1,4, [5],12:i:-. Strains from irrigation water displayed significantly higher susceptibility to antibiotics than those from the other sources. Resistance to ampicillin, streptomycin, sulfonamide, and tetracycline was the most commonly detected resistance profile (R-type), being in serovar S. 1,4, [5],12:i:-, frequently associated to resistance to other antimicrobials. Significant differences in genetic profiles in the two abovementioned Salmonella serotypes were found. None of the plasmid-borne virulence genes investigated were detected in S. 1,4, [5],12:i:- isolates, while those genes, characterized 37.9% of the S. Typhimurium strains. Differences in the prevalence of some molecular targets between the two Salmonella serotypes deserve further study. Importantly, the grvA gene was found exclusively in S. Typhimurium strains, whereas sopE, sodC, gtgB, and gipA were mainly detected, with a statistically significant difference, in S. 1,4, [5],12:i:- isolates.