Prevalence and distribution of Arcobacter spp. in raw milk and retail raw beef

Arcobacter species in milk contamination: a prevalence-based systematic review and meta-analysis

AIMS

Milk is consumed raw or minimally processed and plays a role in the dissemination of pathogens of public health concerns. The present investigation is aimed at assessing the occurrence of pathogenic Arcobacter species in 2945 milk samples.

METHODS AND RESULTS

Arcobacter data systematically retrieved from five repositories until 20 February 2022 according to PRISMA principles were logit transformed and fitted using a generalized linear mixed-effects model. The between-study heterogeneity was estimated as I2-value. Leave-one-out cross-validation and funnel plot with Egger's tests were used to assess the hardiness and bias in the model. The global prevalence of Arcobacter genus in the milk was 12% [95% confidence interval (CI): 7-19%; I2 = 87.3%, 95% CI: 83.0-90.6%] and no publication bias observed (Egger's test: P = 0.112). Arcobacter genus prevalence in milk was 13% (95% CI: 5-30%), 10% (95% CI: 1-46%), and 9% (95% CI: 4-19%) in Europe, South America, and Asia, respectively. Arcobacter butzleri was the most prevalent [8% (95% CI: 4-13%)], followed by A. cryaerophilus [0.6% (95% CI: 0.2-33.2%)] and A. skirrowii [0.19% (95% CI: 0.03-1.2%)]. Also, species-specific prevalence of A. butzleri, A. cryaerophilus, and A. skirrowii varied continentally, but the test for species-specific/continental differences was not significantly different (P > 0.5).

Genotyping, antibiotic resistance and prevalence of Arcobacter species in milk and dairy products

BACKGROUND

Arcobacter spp. has been considered an emerging foodborne pathogen and a hazard to human health. The dairy chain has been isolated from different sources; nevertheless, data on Arcobacter occurrence in raw milk and dairy products in Iran are still scant.

OBJECTIVE

The present study investigates the prevalence, antimicrobial susceptibility and the presence of virulence genes of Arcobacters species isolated from milk and dairy products.

METHODS

Then, a total of 350 raw milk samples and 400 dairy product samples were collected from dairy supply centers in Isfahan, Iran. Presumptive Arcobacter strains were obtained by enriching samples in Oxoid Arcobacter enrichment broth (AEB) followed by the filtration of enrichment product through 0.45-μm pore size membrane filters laid onto non-selective blood at 30°C under microaerophilic conditions. Molecular identification of Arcobacter cryaerophilus and A. butzleri was performed by Polymerase chain reaction (PCR) amplification of the 16S rRNA gene, followed by sequencing. The disc diffusion method was used to determine the antimicrobial susceptibility of isolates. Targeted resistance and virulence genes were detected using multiplex PCR.

RESULTS

The results show a low recovery rate of Arcobacter spp. in milk. Arcobacters were found in all types of milk, except raw camel milk, but were absent from all dairy products. Arcobacter butzleri was the predominant species in raw milk. Detection of virulence genes shows that all virulence genes targeted were found among A. butzleri, and six (cadF, cj1349, irgA, mviN, pldA, tlyA) were found among A. cryaerophilus. All A. butzleri strains and some A. cryaerophilus strains isolated from milk were resistant to amoxicillin-clavulanic acid and tetracycline. All A. cryaerophilus isolates from milk were susceptible to gentamycin, streptomycin, erythromycin and ciprofloxacin. The distribution of resistance genes in Arcobacter strains in milk shows that all isolates carried tet(O) and bla_OXA-61 genes.

CONCLUSIONS

In conclusion, the results indicate a low recovery rate of Arcobacter spp. in milk and milk products. However, a significant number of Arcobacter strains with putative virulence genes may be potential pathogens for humans and an overall increase in Arcobacter resistance to first-line antibiotics. These results highlight the need for regular surveillance of Arcobacter strains in milk and milk products in Iran.

Isolation of Arcobacter spp. and identification of isolates by multiplex PCR from various domestic poultry and wild avian species

Purpose

The purpose of the present study was to determine the extent and seasonal prevalence of Arcobacter spp. in domestic poultry and wild birds in the Kars region of Turkey using multiplex polymerase chain reaction (m-PCR).

Methods

In this study, 1570 samples were collected from domestic poultry and wild avian species. The numbers of collected samples were as follows: 182 fecal samples from chickens, geese, and turkeys from family farms in the Kars region in Turkey; 1089 cloacal swab samples from chickens, geese, ducks, turkeys, and quails from family farms in this region; and 299 fecal samples from wild pigeons, crows, and owls in the same region.

Results

Arcobacter spp. were isolated from 17.43%, 35.77%, 3.63%, 6.87%, and 3.33% of the cloacal swab samples obtained from geese, ducks, chickens, turkeys, and quails, respectively. In the stool samples, Arcobacter spp. were isolated from 9.62%, 13.33%, and 4% of chicken, goose, and turkey samples, respectively. In wild birds, the isolation rates of Arcobacter spp. were 6.6%, 12.15%, and 0% in pigeons, crows, and owls, respectively. Using m-PCR, among 171 Arcobacter spp. isolates obtained from poultry and wild birds, 67, 78, 24, and 2 were identified as Arcobacter cryaerophilus, Arcobacter butzleri, Arcobacter skirrowii, and Arcobacter cibarius, respectively.

Conclusions

Both poultry and wild avian species exhibited variable rates of Arcobacter species positivity. The presence of Arcobacter spp. in the digestive tracts of healthy poultry and wild birds may serve as a potential reservoir for the dissemination of these microbes in the environment and their transmission to other animals and humans.

Arcobacter butzleri: Up-to-date taxonomy, ecology, and pathogenicity of an emerging pathogen

Arcobacter butzleri, recently emended to the Aliarcobacter butzleri comb. nov., is an emerging pathogen causing enteritis, severe diarrhea, septicaemia, and bacteraemia in humans and enteritis, stillbirth, and abortion in animals. Since its recognition as emerging pathogen on 2002, advancements have been made in elucidating its pathogenicity and epidemiology, also thanks to advent of genomics, which, moreover, contributed in emending its taxonomy. In this review, we provide an overview of the up-to-date taxonomy, ecology, and pathogenicity of this emerging pathogen. Moreover, the implication of A. butzleri in the safety of foods is pinpointed, and culture-dependent and independent detection, identification, and typing methods as well as strategies to control and prevent the survival and growth of this pathogen are provided.

Large genetic diversity of Arcobacter butzleri isolated from raw milk in Southern Italy

Arcobacter butzleri is a zoonotic foodborne pathogen able to cause enteric and extraintestinal diseases. Its occurrence in foodstuff is well recognized worldwide but data on its presence in foods from Southern Italy are scarce. In this study the results on the occurrence and genotyping of Arcobacter spp. in bulk milk samples collected in Southern Italy are reported. Out of 484 samples, 64 (13.2%) resulted positive for the presence of Arcobacter spp. Using Real Time PCR but as few as 31.2% of these samples turned out as positive by using the cultural method, showing an overall prevalence of 4.1%. All isolates were identified as A. cryaerophilus using the biochemical identification whilst the sequencing of the atpA gene revealed that all the isolates were A. butzleri. Among the confirmed isolates, 16 different Sequence Types (ST) were identified using the Multi Locus Sequence Typing (MLST), 14 (87.5%) of which were previously unreported. Our survey reveals the presence of A. butzleri in bulk tank milk from Southern Italy and highlights the discrepancy between the two approaches used both for the detection (i.e., real time PCR vs cultural method) and the identification (i.e., biochemical test vs aptA sequencing) of Arcobacter spp In addition, a large genetic diversity among the isolates was detected and this makes the identification of source of the infections very challenging in outbreaks investigation.

Genomic Characterization of Arcobacter butzleri Isolated From Shellfish: Novel Insight Into Antibiotic Resistance and Virulence Determinants

Arcobacter (A.) butzleri is an emerging pathogenic microorganism, whose taxonomy has been recently suggested to be emended to the Aliarcobacter (Al.) butzleri comb. nov. Despite extensive taxonomic analysis, only few fragmented studies have investigated the occurrence and the prevalence of virulence and antibiotic resistance determinants of this species in strains isolated from shellfish. Herein we report for the first time the whole genome sequencing and genomic characterization of two A. butzleri strains isolated from shellfish, with particular reference to the antibiotic, heavy metals and virulence determinants. This study supported the taxonomic assignment of these strains to the Al. butzleri species, and allowed us to identify antibiotic and metal resistance along with virulence determinants, also additional to those previously reported for the only two A. butzleri strains from different environments genomically characterized. Moreover, both strains showed resistance to β-lactams, vanocomycin, tetracycline and erythromycin and susceptibility to aminoglycosides and ciprofloxacin. Beside enlarging the availability of genomic data to perform comparative studies aimed at correlating phenotypic differences associated with ecological niche and geographic distribution with the genetic diversity of A. butzleri spp., this study reports the endowment of antibiotic and heavy metal resistance and virulence determinants of these shellfish-isolated strains. This leads to hypothesize a relatively high virulence of A. butzleri isolated from shellfish and prompt the need for a wider genomic analysis and for in vitro and in vivo studies of more strains isolated from this and other ecological niches, to unravel the mechanism of pathogenicity of this species, and the potential risk associated to their consumption.

Arcobacter spp. in bovine milk: An emerging pathogen with potential zoonotic risk

The aim of the present study was to assess the prevalence and genetic characteristics of Arcobacter spp. in bovine bulk tank milk produced in Apulia Region (Italy). Samples collected from 396 dairy farms, after enrichment in a selective broth, were subjected to an Arcobacter genus - specific Real Time PCR. Positive broths, previously filtered, were seeded on Karmali, MCCD and Columbia Blood Agar plates; presumptive Arcobacter spp. colonies were identified using an amplification and sequencing method and then characterized by Multi-Locus Sequence Typing (MLST). Prevalence of Arcobacter spp. in bovine milk samples was 5% (20/396); A. butzleri was the only isolated species, in agreement with previous studies that reported A. butzleri as the most commonly recovered species in milk and dairy products. MLST analysis of the 20 A. butzleri strains identified 81 alleles and 16 STs. Consistent with previous studies, MLST revealed a high level of heterogeneity between the A. butzleri isolates and confirmed the high discriminatory power of this method and its suitability for epidemiological investigations. This study confirmed the importance of raw milk as a possible source of Arcobacter spp. for humans.

Arcobacter: an emerging food-borne zoonotic pathogen, its public health concerns and advances in diagnosis and control - a comprehensive review

Arcobacter has emerged as an important food-borne zoonotic pathogen, causing sometimes serious infections in humans and animals. Newer species of Arcobacter are being incessantly emerging (presently 25 species have been identified) with novel information on the evolutionary mechanisms and genetic diversity among different Arcobacter species. These have been reported from chickens, domestic animals (cattle, pigs, sheep, horses, dogs), reptiles (lizards, snakes and chelonians), meat (poultry, pork, goat, lamb, beef, rabbit), vegetables and from humans in different countries. Arcobacters are implicated as causative agents of diarrhea, mastitis and abortion in animals, while causing bacteremia, endocarditis, peritonitis, gastroenteritis and diarrhea in humans. Three species including A. butzleri, A. cryaerophilus and A. skirrowii are predominantly associated with clinical conditions. Arcobacters are primarily transmitted through contaminated food and water sources. Identification of Arcobacter by biochemical tests is difficult and isolation remains the gold standard method. Current diagnostic advances have provided various molecular methods for efficient detection and differentiation of the Arcobacters at genus and species level. To overcome the emerging antibiotic resistance problem there is an essential need to explore the potential of novel and alternative therapies. Strengthening of the diagnostic aspects is also suggested as in most cases Arcobacters goes unnoticed and hence the exact epidemiological status remains uncertain. This review updates the current knowledge and many aspects of this important food-borne pathogen, namely etiology, evolution and emergence, genetic diversity, epidemiology, the disease in animals and humans, public health concerns, and advances in its diagnosis, prevention and control.

Occurrence, genetic diversity and antibiotic resistance of Arcobacter sp. in a dairy plant

AIMS

The aim of this study was to evaluate the occurrence, diversity and resistance to antibiotics of Arcobacter sp. in a dairy plant samples.

METHODS AND RESULTS

A total of 75 samples from dairy plant surfaces and materials and several food products collected in different steps of the cheese production process were analysed by culture, under aerobic and microaerobic atmospheric conditions, and by enrichment molecular detection. Isolates were identified and genotyped by ERIC-PCR, and their susceptibility to nine antibiotics was evaluated by agar dilution. Global prevalence of Arcobacter sp. was 42·7%, where 20 of the 42 food samples analysed were positive for A. butzleri by both culture and molecular detection, one for A. marinus by culture and one for A. cryaerophilus by molecular detection only; 10 of the 30 analysed materials and plant surfaces were positive for A. butzleri. All A. butzleri isolates were resistant to nalidixic acid and showed high resistance rates to ampicillin (56·2%) and cefotaxime (97·9%), being all strains susceptible to gentamicin and erythromycin.

CONCLUSIONS

Contamination of dairy plant environment with A. butzleri and its progression along cheese production process were observed, however, the cheese ripening process may have a relevant role in the reduction of the contamination.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study showed the presence of Arcobacter sp. in a dairy plant, displaying its high prevalence and genetic diversity and highlighting its high resistance rates. The data obtained could contribute to further acknowledge the Arcobacter food contamination as a potential health hazard.

Occurrence of putative virulence genes on Arcobacter butzleri isolated from three different environmental sites throughout the dairy chain

AIMS

This comparative study investigated the occurrence of cadF, cj1349, ciaB, pldA, tlyA, hecA, hecB, mviN, irgA and IroE genes in 212 Arcobacter butzleri isolated from three different environmental sites linked to the dairy chain (farms, industrial and artisanal dairy plants) located in three Italian regions (Lombardy, Emilia-Romagna and Calabria).

METHODS AND RESULTS

According to the presence of these genes, different pathotypes (P-types) were determined. The main genes detected were ciaB, mviN, tlyA, cj1349, pldA and cadF, while the least common genes were iroE, hecA, hecB and irgA. TlyA, irgA, hecA, hecB and iroE, which were significantly more frequent in isolates recovered in industrial dairy plants. Twelve P-types were detected. The occurrence of the most frequently detected P-types (P-types 1, 2, 3 and 5) differed significantly (P < 0·001) in relation to both the environmental site and geographical area of isolation. The highest diversity in P-types was observed in industrial dairy plants and in the Calabria region.

CONCLUSIONS

The results of this study show a correlation between the occurrence of putative virulence genes and virulence genotype variability depending on the environmental site and geographical origin of the isolates.

SIGNIFICANCE AND IMPACT OF THE STUDY

The present study provides insights into the similar distribution of putative virulence genes in a dairy chain and other sources' isolates and also into a geographical distribution of some P-types. We have shown that industrial dairy plants may represent an environmental site favouring a selection of the isolates with a higher pathogenetic pattern.

Isolation and identification of Arcobacter species from environmental and drinking water samples

Water plays an important role in the transmission of Arcobacter spp. to animals and humans. The aim of this study was to isolate and characterize Arcobacter spp. from 115 different water samples (66 sewage, 25 rivers, 16 spring water, and 8 drinking water) in Izmir, Turkey. In total, 41 samples (35.7 %) were found positive for Arcobacter spp. by the genus-specific PCR. Arcobacter butzleri was detected in 39 out of 115 samples (33.9 %) including 24 sewage, 13 rivers, and 2 spring water. The remaining Arcobacter spp. (n = 2) isolates could not be identified by m-PCR and 16S rRNA gene sequencing. Based on the phenotypic characterization, most of the Arcobacter species (87.8 %) indicated weak catalase activity. In addition, there were differences in phenotypic patterns among isolated species during growth at 37 °C under microaerobic and aerobic conditions, in the presence of 2 % (39/41) and 3.5 % (32/41) NaCl and 0.04 % TTC (39/41) and on MacConkey agar (38/41). The results of this study indicated that environmental water samples are common sources for Arcobacter spp. Therefore, effective control measures should be taken to protect human health.

Multilocus sequence typing of Arcobacter butzleri isolates collected from dairy plants and their products, and comparison with their PFGE types

AIMS

The present study aimed to determine, by multilocus sequence type (MLST), the heterogeneity level of Arcobacter butzleri isolates and to compare MLST and pulsed-field gel electrophoresis (PFGE) in terms of discriminatory power (DI) as well as unidirectional and bi-directional concordance.

METHODS AND RESULTS

Arcobacter butzleri isolates (N = 133) from dairy products and environmental samples, collected from dairy plants, were characterized by MLST and PFGE with SacII and classified in 29 sequence types (STs), 47 PFGE and 62 type strains (TS). Among the 119 alleles, 19 were previously unreported and the same for all the STs but two. A significant linkage disequilibrium was detected when the complete ST data set was analysed The DIs of MLST, PFGE and their combination were 0·937, 0·953 and 0·965 respectively. The adjusted Wallace coefficients between MLST and PFGE as well as PFGE and MLST were 0·535 and 0·720 respectively; the adjusted Rand coefficient was 0·612.

CONCLUSIONS

The A. butzleri studied population showed recombination to some degree. PFGE showed a DI higher than MLST. Both methods presented good concordance. The TS analysis seems to show persistence of the same strain on time and possible cross-contaminations between food and environmental sites.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study provides insights in the A. butzleri population found in raw milk, cheese, and dairy production plants. The data suggest that MLST and PFGE genotypes correlate reasonably well, although their combination results in optimal resolution.

Global Distribution and Prevalence of Arcobacter in Food and Water

The emerging foodborne and waterborne pathogen, Arcobacter, has been linked to various gastrointestinal diseases. Currently, 19 species are established or proposed; consequently, there has been an increase in the number of publications regarding Arcobacter since it was first introduced in 1991. To better understand the potential public health risks posed by Arcobacter, this review summarizes the current knowledge concerning the global distribution and the prevalence of Arcobacter in food and water. Arcobacter spp. were identified in food animals, food-processing environments and a variety of foods, including vegetables, poultry, beef, dairy products, seafood, pork, lamb and rabbit. A wide range of waterbodies has been reported to be contaminated with Arcobacter spp., such as wastewater, seawater, lake and river water, drinking water, groundwater and recreational water. In addition, Arcobacter has also been isolated from pets, domestic birds, wildlife, zoo and farm animals. It is expected that advancements in molecular techniques will facilitate better detection worldwide and aid in understanding the pathogenicity of Arcobacter. However, more extensive and rigorous surveillance systems are needed to better understand the occurrence of Arcobacter in food and water in various regions of the world, as well as uncover other potential public health risks, that is antibiotic resistance and disinfection efficiency, to reduce the possibility of foodborne and waterborne infections.

Arcobacter butzleri, Arcobacter cryaerophilus, and Arcobacter skirrowii Circulation in a Dairy Farm and Sources of Milk Contamination

Even though dairy cows are known carriers of Arcobacter species and raw or minimally processed foods are recognized as the main sources of human Arcobacter infections in industrialized countries, data on Arcobacter excretion patterns in cows and in milk are scant. This study aimed to identify potentially pathogenic Arcobacter species in a dairy herd and to investigate the routes of Arcobacter transmission among animals and the potential sources of cattle infection and milk contamination. A strategy of sampling the same 50 dairy animals, feed, water, and milk every month for a 10-month period, as well as the sampling of quarter milk, animal teats, the milking environment, and animals living on the farm (pigeons and cats), was used to evaluate, by pulsed-field gel electrophoresis (PFGE), the characteristic patterns in animals, their living environment, and the raw milk they produced. Of the 463 samples collected, 105 (22.6%) were positive for Arcobacter spp. by culture examination. All the matrices except quarter milk and pigeon gut samples were positive, with prevalences ranging from 15 to 83% depending on the sample. Only three Arcobacter species, Arcobacter cryaerophilus (54.2%), A. butzleri (34.2%), and A. skirrowii (32.3%), were detected. PFGE analysis of 370 isolates from positive samples provided strong evidence of Arcobacter circulation in the herd: cattle likely acquire the microorganisms by orofecal transmission, either by direct contact or from the environment, or both. Water appears to be a major source of animal infection. Raw milk produced by the farm and collected from a bulk tank was frequently contaminated (80%) by A. butzleri; our PFGE findings excluded primary contamination of milk, whereas teats and milking machine surfaces could be sources of Arcobacter milk contamination.

Insights in the pathogenesis and resistance of Arcobacter: A review

Arcobacter genus currently comprises 18 recognized species, among which Arcobacter butzleri, Arcobacter cryaerophilus and Arcobacter skirrowii have been associated with human and animal disease. Although these organisms, with special emphasis A. butzleri, are emerging as clinical pathogens, several aspects of their epidemiology and virulence are only starting to be clarified. In vitro human and animal cell culture assays have been used to show that several Arcobacter species can adhere to and invade eukaryotic cells, induce an immune response and produce toxins that damage host cells. In addition, data from genome sequencing highlighted several potential markers that may be helpful candidates for the study and understanding of these mechanisms; however, more work is necessary to clarify the molecular mechanisms involved in Arcobacter virulence. Arcobacter can be considered a relatively robust organism showing to be able to survive in adverse conditions, as the ones imposed by food processing and storage. Moreover, these bacteria have shown increased antibiotic resistance, along with high multidrug resistance. In this review, we seek to update the state-of-the-art concerning Arcobacter distribution, its interaction with the host, the trends of antibiotic resistance, its ability to survive, and finally the use of natural antimicrobials for control of Arcobacter.

Arcobacter butzleri in sheep ricotta cheese at retail and related sources of contamination in an industrial dairy plant

This study aimed to evaluate Arcobacter species contamination of industrial sheep ricotta cheese purchased at retail and to establish if the dairy plant environment may represent a source of contamination. A total of 32 sheep ricotta cheeses (1.5 kg/pack) packed in a modified atmosphere were purchased at retail, and 30 samples were collected in two sampling sessions performed in the cheese factory from surfaces in contact with food and from surfaces not in contact with food. Seven out of 32 samples (21.9%) of ricotta cheese collected at retail tested positive for Arcobacter butzleri at cultural examination; all positive samples were collected during the same sampling and belonged to the same batch. Ten surface samples (33.3%) collected in the dairy plant were positive for A. butzleri. Cluster analysis identified 32 pulsed-field gel electrophoresis (PFGE) patterns. The same PFGE pattern was isolated from more than one ricotta cheese sample, indicating a common source of contamination, while more PFGE patterns could be isolated in single samples, indicating different sources of contamination. The results of the environmental sampling showed that A. butzleri may be commonly isolated from the dairy processing plant investigated and may survive over time, as confirmed by the isolation of the same PFGE pattern in different industrial plant surface samples. Floor contamination may represent a source of A. butzleri spread to different areas of the dairy plant, as demonstrated by isolation of the same PFGE pattern in different production areas. Isolation of the same PFGE pattern from surface samples in the dairy plant and from ricotta cheese purchased at retail showed that plant surfaces may represent a source of A. butzleri postprocessing contamination in cheeses produced in industrial dairy plants.

Prevalence and antimicrobial susceptibility of Arcobacter species in cow milk, water buffalo milk and fresh village cheese

In this study, the presence of Arcobacter spp. was examined in cow milk (n=50), water buffalo (WB) milk (n=50) and fresh village cheese (n=50) samples. The 16S rDNA-RFLP method was used for the identification of Arcobacter spp. The disc diffusion method was used to investigate the susceptibility of all strains identified to 18 different antimicrobial substances. The most commonly isolated Arcobacter species were found to be Arcobacter butzleri (38.89%), Arcobacter cryaerophilus (22.23%) and Arcobacter skirrowii (11.12%) in cow milk; A. cryaerophilus (33.33%), Arcobacter cibarius (20.83%) and A. butzleri (12.50%) in WB milk; and A. skirrowii (28.57%), A. butzleri (21.43%) and A. cryaerophilus (14.29%) in fresh village cheese. This is the first study to identify the presence of Arcobacter nitrofigilis, Arcobacter cloacae, Arcobacter halophilus, Arcobacter bivalviorum and A. cibarius species in analyzed samples. It was found that all of the A. cryaerophilus (n:16) isolates were resistant to cefoperazone, cloxacillin and penicillin G; all of the A. skirrowii (n:12) and A. butzleri (n:10) isolates were resistant to cefoperazone, tetracycline, ampicillin, erythromycin, cloxacillin and penicillin G. It was concluded that cow milk, WB milk and fresh village cheese samples are an important source of Arcobacter species and pose a risk to public health.

Short communication: occurrence of Arcobacter species in industrial dairy plants

The present study investigated the presence of Arcobacter spp. in industrial dairy plants. Between February and September 2013, pasteurized milk used for cheesemaking, processing and cleaning water, cheese, and environmental samples from different plant sites, including surfaces in contact or not in contact with food, were sampled. A total of 126 samples were analyzed by the cultural method and isolates were identified by multiplex PCR. Arcobacter spp. were isolated from 22 of 75 environmental samples (29.3%): of them, 22.7% were surfaces in contact with food and 38.7% surfaces not in contact with food. A total of 135 Arcobacter spp. isolates were obtained; of these, 129 and 6 were identified as Arcobacter butzleri and Arcobacter cryaerophilus, respectively. All food processing water and pasteurized milk samples were negative for Arcobacter species. We were not able to determine the primary source of contamination, but the isolation of both A. butzleri and A. cryaerophilus in surfaces in contact with food before and during manufacturing suggests that Arcobacter spp. are not or are only partially affected by routine sanitizing procedures in the industrial dairy plants studied. The efficacy of sanitizing procedures should be evaluated and further studies are needed to determine whether certain Arcobacter strains persist for long periods of time in industrial dairy plants and whether they can survive in different types of cheese in cases of postprocessing contamination.

Occurrence and genetic diversity of Arcobacter butzleri in an artisanal dairy plant in Italy

The present study aimed to investigate the presence, distribution, and persistence of Arcobacter spp. in an artisanal dairy plant and to test the isolates to determine their different genotypes in the processing plant and in foods. Samples were collected in an artisanal cheese factory on four occasions between October and December 2012. Food samples (raw milk, ricotta cheese, mozzarella cheese, and conditioning liquid), water samples, and environmental samples were analyzed by the culture method; isolates were identified by multiplex PCR and genotyped by pulsed-field gel electrophoresis (PFGE) analysis. Arcobacter butzleri was isolated from 29 out of 59 samples (46.6%), 22 of which were from environmental samples and 7 of which were from food samples. Cluster analysis divided the strains into 47 PFGE patterns: 14 PFGE clusters and 33 unique types. Our findings indicate that the plant harbored numerous A. butzleri pulsotypes and that the manual cleaning and sanitation in the studied dairy plant do not effectively remove Arcobacter. The recurrent isolation of A. butzleri suggests that the environmental conditions in the dairy plant constitute a good ecological niche for the colonization of this microorganism. In some cases, the presence of indistinguishable strains isolated from the same facilities on different sampling days showed that these strains were persistent in the processing environment.

Prevalence and genetic diversity of arcobacter in food products in the north of Spain

The bacterial contamination of food products can cause serious public health problems. Interest in Arcobacter contamination has increased due to the relationship between these bacteria and human enteritis. We studied the prevalence and genetic diversity of Arcobacter species at the retail level in the province of Alava in Basque Country, Spain. The results showed a high genetic diversity and indicated the regular presence of the main Arcobacter spp. associated with human enteric illness in food products. Arcobacter butzleri, Arcobacter cryaerophilus, and Arcobacter skirrowii were detected with an overall prevalence close to 40% and were isolated from 15 (42.8%) fresh cow's milk samples, 12 (73.3%) shellfish samples, 11 (55%) chicken samples, 2 (10%) pork samples, and 1 (5%) beef sample. The results indicate the need to investigate the impact of Arcobacter spp. on public health.

Survival of Arcobacter butzleri during production and storage of artisan water buffalo mozzarella cheese

Water buffalo mozzarella cheese (WBMC) is a fresh stretched cheese produced from whole chilled buffalo milk. Although pasteurization of milk and the use of defined starter cultures are recommended, traditional technology involving unpasteurized milk and natural whey cultures is still employed for WBMC production in Italy. The purpose of this study was to assess the behavior of Arcobacter butzleri during WBMC production and storage under different temperature conditions (5, 10, and 20 °C). Raw milk was experimentally inoculated with one reference strain and two isolates of A. butzleri, and the count was monitored during WBMC production and storage. The bacterial count of A. butzleri decreased during curd ripening (from 7.83 log colony-forming units (CFU)/g to 4.14 log CFU/g in about 4 h) and a further decrease (>4 log CFU/g) was observed at the end of curd stretching. During storage testing, A. butzleri was never detected by direct plating, whereas it was recovered from 12 of the total 162 WBMC until the end of storage testing by enrichment. The results revealed that A. butzleri is able to survive during WBMC production and storage at different temperature conditions. Consequently, traditional WBMC produced from raw milk could represent a potential source of Arcobacter infection for humans.

Presence of Campylobacter and Arcobacter species in in-line milk filters of farms authorized to produce and sell raw milk and of a water buffalo dairy farm in Italy

The objectives of this study were to investigate the presence of Campylobacter spp. and Arcobacter spp. in dairy herds authorized for the production and sale of raw milk and in a water buffalo dairy farm, and to test the antimicrobial susceptibility of the isolates. A total of 196 in-line milk filters were collected from 14 dairy farms (13 bovine and 1 water buffalo) for detection of Campylobacter spp. and Arcobacter spp. by microbiological culture. For each farm investigated, 1 isolate for each Campylobacter and Arcobacter species isolated was tested using the Etest method (AB Biodisk, Solna, Sweden) to evaluate the susceptibility to ciprofloxacin, tetracycline, chloramphenicol, ampicillin, erythromycin, and gentamicin. A total of 52 isolates were detected in 49 milk filters in 12 farms (85.7%) out of 14 and the isolates were identified as Campylobacter jejuni (6), Campylobacter hyointestinalis ssp. hyointestinalis (8), Campylobacter concisus (1), Campylobacter fetus ssp. fetus (1), Arcobacter butzleri (22), and Arcobacter cryaerophilus (14). The small number of isolates tested for antimicrobial susceptibility precludes any epidemiological consideration but highlights that all Campylobacter isolates were susceptible to macrolides, which are the first-choice drugs for the treatment of campylobacteriosis, and that resistance to fluoroquinolones and tetracycline was detected; for Arcobacter isolates, resistance to ampicillin and chloramphenicol was detected. The sale of raw milk for human consumption by self-service automatic vending machines has been allowed in Italy since 2004 and the presence of C. jejuni in in-line milk filters confirms that raw milk consumption is a significant risk factor for human infection. The high occurrence of emerging Campylobacter spp. and Arcobacter spp. discovered in dairy farms authorized for production and sale of raw milk represents an emerging hazard for human health.