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Results reveal that low-molecular-weight DNA synthesized by retron reverse transcriptase of Salmonella enterica is double-stranded with single-stranded overhangs unlike the more commonly produced single-stranded DNA by procaryotes. Data indicate that the plasmid containing three open reading frames confers phage resistance onto the host cell independent of double-stranded DNA synthesis.

Although Campylobacter jejuni is the pathogen responsible for the most common foodborne illness, tracing of the infection source remains challenging due to its highly variable genome. Therefore, one of the aim of the study was to compare three genotyping methods (MLST, PFGE, and mP-BIT) to determine the most effective genotyping tool. C. jejuni strains were divided into 4 clusters based on strain similarity in the cgMLST dendrogram. Subsequently, the dendrograms of the 3 tested methods were compared to determine the accuracy of each method compared to the reference cgMLST method. Moreover, a cost-benefit analysis has showed that MLST had the highest inverse discrimination index (97%) and required less workflow, time, fewer consumables, and low bacterial sample quantity. PFGE was shown to be obsolete both because of its low discriminatory power and the complexity of the procedure. Similarly, mP‑BIT showed low separation results, which was compensated by its high availability. Therefore, our data showed that MLST is the optimal tool for genotyping C. jejuni. Another aim was to compare the antimicrobial resistance to ciprofloxacin, erythromycin, and tetracycline in C. jejuni strains isolated from human, water, air, food, and animal samples by two gene sequence-based prediction methods and to compare them with the actual susceptibility of C. jejuni strains using the disc diffusion method. Both tools, ResFinder and RGI, synchronously predict the antimicrobial susceptibility of C. jejuni and either can be used., (© 2023. The Author(s).)

Aims: The purpose of the study was to evaluate the occurrence of Campylobacter jejuni and Campylobacter coli in the aquatic environment based on the water origin, seasonality and physico-chemical properties., Methods and Results: The occurrence of C. jejuni and C. coli was determined in waste (29) or surface (56) waters in four different seasons. The air and water temperatures were measured during sampling and chemical analyses of water samples for ammonium, chloride, chlorine, nitrite, nitrate, phosphate and iron were performed. The thermotolerant Campylobacter spp. were more frequently detected in wastewater (59%; 17 positive samples) compared to surface water (38%; 21 positive samples), with the highest rate in autumn (67% of samples positive) and with a higher C. coli occurrence than C. jejuni (31% vs. 26%). Ammonium (above 0.2 mg/L) and chloride ion concentrations (above 60 mg/L) favour C. jejuni. Similarly, C. coli occurrence in water was supported by ammonium (above 0.2 mg/L), chloride (above 60 mg/L) and in addition by phosphate ion concentrations (below 0.7 mg/L)., Conclusions: Campylobacter presence in water is influenced by physico-chemical parameters such as concentrations of ammonium and chloride ions., Significance and Impact of the Study: Water environment is an alternative source of Campylobacter. The concentration of ammonium and chloride ions can be used as a basis for successful prediction of the potential occurrence of C. jejuni and C. coli in wastewater and surface water in future., (© 2021 The Authors. Journal of Applied Microbiology published by John Wiley & Sons Ltd on behalf of Society for Applied Microbiology.)

Microbiota can significantly contribute to colorectal cancer initiation and development. It was described that E. coli harbouring polyketide synthase (pks) genes can synthetize bacterial toxin colibactin, which was first described by Nougayrede's group in 2006. E. coli positive for pks genes were overrepresented in colorectal cancer biopsies and, therefore, prevalence and the effect of pks positive bacteria as a risk factor in colorectal cancer development is in our interest. Interestingly, pks gene cluster in E. coli shares a striking 100% sequence identity with K. pneumoniae, suggesting that their function and regulation are conserved. Moreover, K. pneumoniae can express a variety of virulence factors, including capsules, siderophores, iron-scavenging systems, adhesins and endotoxins. It was reported that pks cluster and thereby colibactin is also related to the hypervirulence of K. pneumoniae. Acquisition of the pks locus is associated with K. pneumoniae gut colonisation and mucosal invasion. Colibactin also increases the likelihood of serious complications of bacterial infections, such as development of meningitis and potentially tumorigenesis. Even though K. pneumoniae is undoubtedly a gut colonizer, the role of pks positive K. pneumoniae in GIT has not yet been investigated. It seems that CRC-distinctive microbiota is already present in the early stages of cancer development and, therefore, microbiome analysis could help to discover the early stages of cancer, which are crucial for effectiveness of anticancer therapy. We hypothesize, that pks positive K. pneumoniae can be a potential biomarker of tumour prevalence and anticancer therapy response., (Copyright © 2021 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

The natural environment and water are among the sources of Campylobacter jejuni and Campylobacter coli . A limited number of protocols exist for the isolation of campylobacters in poorly filterable water. Therefore, the goal of our work was to find a more efficient method of Campylobacter isolation and detection from wastewater and surface water than the ISO standard. In the novel rapid culture method presented here, samples are centrifuged at high speed, and the resuspended pellet is inoculated on a filter, which is placed on Campylobacter selective mCCDA agar. The motile bacteria pass through the filter pores, and mCCDA agar suppresses the growth of background microbiota on behalf of campylobacters. This culture-based method is more efficient for the detection and isolation of Campylobacter jejuni and Campylobacter coli from poorly filterable water than the ISO 17995 standard. It also is less time-consuming, taking only 72 h and comprising three steps, while the ISO standard method requires five or six steps and 144-192 h. This novel culture method, based on high-speed centrifugation, bacterial motility, and selective cultivation conditions, can be used for the detection and isolation of various bacteria from water samples.

Background: In order to estimate the prevalence of plasmid borne colistin resistance and to characterize in detail the mcr -positive isolates, we carried out a sentinel testing survey on the intestinal carriage of plasmid-mediated colistin-resistant Enterobacteriaceae in hospitalized patients. Methods: Between June 2018 and September 2019, 1922 faecal samples from hospitalised patients were analysed by selective culture in presence of colistin (3.5 mg/L), and in parallel by direct detection of the mcr-1 to mcr-8 genes by qPCR. The mcr -positive isolates were characterised by whole-genome sequencing. Results: The prevalence of the mcr-1 gene was 0.21% ( n = 4/1922); the mcr-2 to 8 genes were not detected. The mcr-1 gene was found to be localised in the IncX4 ( n = 3) and IncHI2 ( n = 1) plasmid type. One Escherichia coli isolate was susceptible to colistin due to the inactivation of the mcr-1 gene through the insertion of the IS2 element; however, the colistin resistance was inducible by culture in low concentrations of colistin. One human mcr-1 positive E. coli isolate was related genetically to the mcr-1 E. coli isolate derived from turkey meat of Czech origin. Conclusions: mcr -mediated colistin resistance currently poses little threat to patients hospitalised in Czech healthcare settings. The presence of the mcr-1 gene in the human population has a possible link to domestically produced, retail meat.

The aim of our study was to determine complete nucleotide sequence of mcr-1- carrying plasmids from Enterobacterales isolates recovered from domestic and imported raw retailed meat and compare them with plasmids available at the GenBank sequence database. A set of 16 plasmids originating from Escherichia coli ( n = 13), Klebsiella pneumoniae ( n = 2), and Citrobacter braakii ( n = 1) were analyzed. In our previous study, data from whole genome sequencing showed that mcr-1 gene was located on plasmids of different incompatibility groups (IncHI2, IncI2, and IncX4). The IncI2 ( n = 3) and IncX4 ( n = 8) plasmids harbored mcr-1.1 gene only, whereas IncHI2 sequence type 4 plasmids ( n = 5) carried large multidrug resistance (MDR) regions. MDR regions of IncHI2 plasmids included additional antimicrobial resistance genes conferring resistance to β-lactams ( bla TEM-1 ), aminoglycosides [ aadA1, aadA2 , and aph(6)-Id ], macrolides [ mef (B)], tetracycline ( tetA, tetR ), and sulphonamides ( sul1, sul2 , and sul3 ). Likewise, IncHI2 plasmids carried several insertion sequences including IS 1 , IS 3 , IS 26 , IS 1326 , and IS Apl1 . In conclusion, our findings confirmed the involvement of IncX4, IncI2, and IncHI2 plasmids in the dissemination of mcr-1.1 gene in several environmental niches, as in samples of retail meat originating from different geographical regions. In contrast to IncX4 and IncI2, IncHI2 plasmids were more diverse and carried additional genes for resistance to heavy metals and multiple antimicrobials., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Zelendova, Papagiannitsis, Valcek, Medvecky, Bitar, Hrabak, Gelbicova, Barakova, Kutilova, Karpiskova and Dolejska.)

Environmental adaptation of Listeria monocytogenes is a complex process involving various mechanisms that can contribute to their survival in the environment, further spreading throughout the food chain and the development of listeriosis. The aim of this study was to analyze whole-genome sequencing data in a set of 270 strains of L. monocytogenes derived from human listeriosis cases and food and environmental sources in order to compare the prevalence and type of genetic determinants encoding cadmium, arsenic, and benzalkonium chloride resistance. Most of the detected genes of cadmium (27.8%), arsenic (15.6%), and benzalkonium chloride (7.0%) resistance were located on mobile genetic elements, even in phylogenetically distant lineages I and II, which indicates the possibility of their horizontal spread. Although no differences were found in the prevalence of these genes between human and food strains, they have been detected sporadically in strains from the environment. Regarding cadmium resistance genes, cadA1C1_ Tn 5422 predominated, especially in clonal complexes (CCs) 121, 8, and 3 strains. At the same time, qacH_ Tn 6188 -encoding benzalkonium chloride resistance was most frequently detected in the genome of CC121 strains. Genes encoding arsenic resistance were detected mainly in strains CC2 (located on the chromosomal island LGI2) and CC9 (carried on Tn 554 ). The results indicated a relationship between the spread of genes encoding resistance to cadmium, arsenic, and benzalkonium chloride in certain serotypes and CCs and showed the need for a more extensive study of L. monocytogenes strains to better understand their ability to adapt to the food production environment., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Gelbicova, Florianova, Hluchanova, Kalova, Korena, Strakova and Karpiskova.)

Background: Travellers were recognized as a risk cohort that can be colonized by mcr-1-mediated colistin-resistant Enterobacteriaceae. We aimed to investigate the carriage of mcr-mediated colistin resistance in Enterobacteriaceae in Czech travellers or expatriates residing temporarily in the Czech Republic., Methods: Between August 2018 and September 2019, the stool samples were cultured in enrichment broth. The enriched cultures were tested for the presence of the mcr-1-8 genes and inoculated onto selective agar with colistin. Colistin-resistant Enterobacteriaceae were tested for the presence of the mcr-1-8 genes; the mcr-positive isolates were characterised by whole genome sequencing., Results: From the 177 stool samples, 15 colistin-resistant Enterobacteriaceae isolates were cultured (7.9%); two of the E. coli isolates carried the mcr-1 gene (1.1%). In the E. coli multilocus sequence type (ST) 156, the mcr-1 gene was located in an ISApl1-mcr-1-orf-ISApl1 (Tn6330) and incorporated into the chromosome; in the E. coli ST23 isolate, the mcr-1 gene was harboured by the plasmid IncX4. Both of the mcr-1 positive E. coli isolates were multidrug-resistant and one isolate was an extended-spectrum β-lactamase producer (bla CTX-M-27 )., Conclusion: Patients with an international travel history should be monitored for the carriage of the mcr-1 gene in order to prevent its dissemination into healthcare settings., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

The microaerophilic pathogen Campylobacter jejuni is a leading bacterial cause of human gastroenteritis in developed countries. Even though it has a reputation as a fastidious organism, C. jejuni is widespread and can be easily isolated from various animals, food, and environmental sources. It is suggested that an ability to form biofilms is probably necessary for the survival of C. jejuni under harsh environmental conditions. The first step required for successful biofilm formation is adhesion to a suitable surface. Therefore, in this work, the degree of adhesion was evaluated, followed by characterization and quantification of biofilms using confocal laser scanning microscopy (CLSM). A total of 15 isolates of C. jejuni were used in the experiments (12 isolates from surface and waste waters, 1 human clinical, 1 food and 1 ACTT BAA-2151 collection strain, all samples originated from the Czech Republic). Regardless of the sample origin, all C. jejuni isolates were able to adhere to the polystyrene surface within 30 min, with the number of attached cells increasing with the time of incubation. The resulting data showed that all isolates were able to form complex voluminous biofilms after 24 h of cultivation. The average amount of biovolume ranged from 3.59 × 10 6 µm 3 to 17.50 × 10 6 µm 3 in isolates obtained from different sources of water, 16.79 × 10 6 µm 3 in the food isolate and 10.92 × 10 6 µm 3 in the collection strain. However, the highest amount of biomass was produced by the human clinical isolate (25.48 × 10 6 µm 3 ). Similar to the quantity, the architecture of the biofilms also differed, from a rugged flat monolayer of cells to large clustered structures. Further, all isolates were tested for the presence of the luxS gene, as the luxS /AI-2 (autoinducer-2) quorum sensing pathway has been previously connected with enhanced biofilm formation. Two isolates originated from surface waters did not possess the luxS gene. These isolates formed thinner and sparser biofilms lacking the presence of significant clusters. However, the ability to adhere to the surface was preserved. The sequencing of the luxS -containing fragments shown a high similarity of the luxS gene among the isolates., (Copyright © 2020 Shagieva, Teren, Michova, Strakova, Karpiskova and Demnerova.)

We investigated the occurrence of plasmid-mediated colistin resistance in Enterobacteriaceae in turkey meat produced in the Czech Republic as well as in turkey meat imported into the Czech Republic from other European Union countries. Seventeen samples of raw turkey meat from the Czech Republic (n = 4), Hungary (n = 2), Poland (n = 6) and Germany (n = 5) were cultured in peptone water at 37 °C overnight and the enriched cultures were tested for the presence of mcr-1-5 genes. PCR-positive enriched cultures were inoculated onto selective agar with colistin (3.5 mg/L). A minimal inhibitory concentration (MIC) of colistin was determined by using the broth microdilution method in PCR-positive isolates. In addition, a macrorestriction analysis was performed using XbaI endonuclease. Of 17 meat samples, 12 samples from Poland (6/6), Germany (3/5) and the Czech Republic (3/4) proved positive for the presence of the mcr-1 gene. Forty-two isolates carrying the mcr-1 gene were obtained: Escherichia coli (n = 39) revealing 32 distinct XbaI profiles and Klebsiella pneumoniae (n = 3) with 2 distinct XbaI profiles. The minimal inhibitory concentration (MIC) of the mcr-1 positive isolates was as follows: 4 mg/L (n = 28), 8 mg/L (n = 12), 32 mg/L (n = 1) and 64 mg/L (n = 1). The high prevalence (70.6%; 12/17 samples) of mcr-1-mediated colistin-resistant Enterobacteriaceae found in the turkey meat samples analysed in this study, builds on previously published evidence that poultry, and their products, represent a substantial risk for the dissemination of plasmid-mediated colistin resistance in Europe.

Here, we describe two plasmids carrying mcr-4.3 in two Acinetobacter baumannii strains isolated from imported food and a clinical sample. The comparative analysis of these plasmids, with two other plasmids reported in the NCBI database, highlighted the common origin of the plasmidic structure carrying mcr-4.3 This is the first case of the mcr-4.3 gene in a A. baumannii strain isolated from a clinical case in Europe. We hypothesize that food import is initiating the spread in Czech Republic., (Copyright © 2019 American Society for Microbiology.)

Environmental matrices and food products are hypothesized to be sources of Cronobacter spp. The severity of neonatal infections, increasing number of cases in elderly and immunocompromised individuals, as well as isolation of Cronobacter spp. from clinical materials demands that more attention should be paid to Cronobacter spp. detection and occurrence of the bacteria in food products. Here, a total of 175 samples of ready-to-eat vegetables, frozen vegetables, and sprouted seeds were collected during a period of 1 year and examined for the presence of Cronobacter spp. using a cultivation method with two different sample preparations and real-time polymerase chain reaction (qPCR). In total, Cronobacter spp. were detected in 22.3% of tested samples using cultivation. In comparison, direct qPCR detected Cronobacter spp. in 37.7% of these samples (p < 0.01; Fisher's exact test) and the numbers of genome equivalents per gram reached 10 8 in some samples of sprouts. Cronobacter spp. were isolated from 51.4%, 37.2%, and 5.2% samples of sprouts, frozen vegetables, and cut green leaves/salads, respectively. Using qPCR, the most frequently contaminated sample types were sprouts (91.4%) and frozen vegetables (60.5%), whereas the rate of positivity for cut green leaves/salads was, in comparison, only 8.2% (p < 0.01; χ 2 -test for independence). PRACTICAL APPLICATION: This study provided valuable information on the occurrence of Cronobacter spp. in ready-to-eat vegetables using cultivation and qPCR. Cronobacter spp. are emerging opportunistic pathogens that can be present in food of plant origin. Cronobacter spp. were isolated from sprouts, frozen vegetables, and cut green leaves/salads, and the numbers of genome equivalents per gram reached 10 8 in some samples of sprouts., (© 2018 Institute of Food Technologists®.)

Staphylococcus aureus is a major food-borne pathogen due to the production of enterotoxin and is particularly prevalent in contaminated milk and dairy products. The lactic acid bacteria (LAB) are widely used as biocontrol agents in fermented foods which can inhibit pathogenic flora. In our work, we investigated the influence of three strains of LAB (Lactobacillus plantarum, Streptococcus thermophilus and Enterococcus durans) on the relative expression of three enterotoxin genes (sea, sec, sell) and eight virulence and/or regulatory genes (sarA, saeS, codY, srrA, rot, hld/RNAIII, agrA/RNAII, sigB) in two S. aureus strains (MW2 and Sa1612) in TSB and reduced-fat milk (1.5 %) at 30 °C over a 24-h period. The tested LAB and S. aureus strains proved to be mutually non-competitive or only slightly competitive during co-cultivation. In addition, under the above-mentioned conditions, differential gene expression between the S. aureus MW2 and Sa1612 strains was well documented. S. aureus growth was changed in mixed culture with LAB; however, its effect on the repression of sea and sec expression correlated with production of these virulence factors. In comparison, the presence of LAB strains generally inhibited the expression of sec, sell, sarA, seaS, agrA/RNAII and hld/RNAIII genes. The effect of LAB strains presence on the expression of sea, codY, srrA, rot and sigB genes was medium, time, LAB and S. aureus strain specific. SEA and SEC production was significantly reduced in milk compared to TSB in pure culture. After the 24-h cultivation, S. aureus MW2 and Sa1612 SEC production was 187 and 331 times lower in milk compared to TSB, respectively (0.07 and 0.39 ng/mL in milk, versus 13.1 and 129.2 ng/mL in TSB, respectively). At the same time S. aureus MW2 and Sa1612 SEA production was 77 and 68 times lower in milk compared to TSB, respectively (0.99 and 0.17 ng/mL in milk, versus 76.4 and 11.5 ng/mL in TSB, respectively). This study has revealed new insights into the interaction between S. aureus and LAB (L. plantarum, S. thermophilus, E. durans) on the level of the expression and/or production of S. aureus enterotoxins, regulatory and virulence genes in different media, including milk. This study provides data which may improve the quality of food production.

The Cronobacter genus (previously known as Enterobacter sakazakii) comprises seven species (Cronobacter sakazakii, Cronobacter malonaticus, Cronobacter muytjensii, Cronobacter turicensis, Cronobacter dublinensis, Cronobacter universalis and Cronobacter condimenti)which cause serious infections in neonates and immunocompromised people.Most of the documented outbreaks of these bacteria have been associated with consumption of contaminated powdered infant formula. The plant environment is considered to be the natural habitat of these bacteria. Therefore, a total number of 563 samples of vegetables, fruit, water and environmental swabs were collected from local farms and supermarkets in the Czech Republic and investigated for the presence of Cronobacter spp. The obtained 45 isolates (8.0%) were further characterized by phenotyping (antimicrobial resistance, capsule and pigment production) and genotyping (fusA sequencing,MLST, PCR-serotyping) methods. Most of the Cronobacter isolates (42.2%) were identified as C. sakazakii, followed by C. turicensis (31.1%), C. dublinensis (22.2%), C. malonaticus (2.2%) and C. universalis (2.2%). The 25 identified sequence types, out of which 17 were unique for only one strain, indicated a high diversity of strains. C. sakazakii sequence type 4 (ST 4), which has been associated with many cases of meningitis, was isolated only in one case. A strong association of C. turicensis and C. dublinensis with the plant environment can be deduced from our results.

We investigated the presence and epidemiological relatedness of Salmonella isolates from a wastewater treatment plant (WWTP) in Brno, Czech Republic and from nestlings of black-headed gulls (Chroicocephalus ridibundus) at the Nove Mlyny waterworks, situated 35 km downstream from the WWTP. During 2012, we collected 37 wastewater samples and 284 gull cloacal swabs. From wastewater samples, we obtained 89 Salmonella isolates belonging to 19 serotypes. At least one resistant strain was contained in 89% of those samples. Ten different serotypes of Salmonella were detected in 38 young gulls, among which 14 (37%) were resistant to antimicrobials. Wastewater isolates were mostly resistant to sulphonamides and tetracycline, gull isolates to tetracycline and ampicillin. We detected the occurrence of blaTEM-1,tet(A), tet(B), tet(G), sul1, sul2, sul3, floR and strA resistance genes. For the first time, we identified a class 1 integron with the dfrA12-orfF-aadA2 gene cassette in S. Infantis. Using pulsed-field gel electrophoresis, we confirmed the presence of identical clusters of S. Agona, S. Enteritidis PT8, S. Infantis and S. Senftenberg in wastewater and black-headed gulls, thus indicating the possibility of resistant Salmonella isolates spreading over long distances in the environment., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Objectives: The objective of this study was to investigate the silver gull as an indicator of environmental contamination by salmonellae and carbapenemase-producing Enterobacteriaceae (CPE) in south-east Australia., Methods: A total of 504 cloacal samples were collected from gull chicks at three nesting colonies in New South Wales, Australia [White Bay (n = 144), Five Islands (n = 200) and Montague Island (n = 160)] and were examined for salmonellae and CPE. Isolates were tested for carbapenemase genes and susceptibility to 14 antibiotics. Clonality was determined by PFGE and MLST. Genetic context and conjugative transfer of the carbapenemase gene were determined., Results: A total of 120 CPE of 10 species, mainly Escherichia coli (n = 85), carrying the gene blaIMP-4, blaIMP-38 or blaIMP-26 were obtained from 80 (40%) gulls from Five Islands. Thirty percent of birds from this colony were colonized by salmonellae. Most isolates contained the gene within a class 1 integron showing a blaIMP-4-qacG-aacA4-catB3 array. The blaIMP gene was carried by conjugative plasmids of variable sizes (80-400 kb) and diverse replicons, including HI2-N (n = 30), HI2 (11), A/C (17), A/C-Y (2), L/M (5), I1 (1) and non-typeable (6). Despite the overall high genetic variability, common clones and plasmid types were shared by different birds and bacterial isolates, respectively., Conclusions: Our data demonstrate a large-scale transmission of carbapenemase-producing bacteria into wildlife, likely as a result of the feeding habits of the birds at a local waste depot. The isolates from gulls showed significant similarities with clinical isolates from Australia, suggesting the human origin of the isolates. The sources of CPE for gulls on Five Islands should be explored and proper measures applied to stop the transmission into the environment., (© The Author 2015. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy.)

Soil and water are suggested to represent pivotal niches for the transmission of Listeria monocytogenes to plant material, animals, and the food chain. In the present study, 467 soil and 68 water samples were collected in 12 distinct geological and ecological sites in Austria from 2007 to 2009. Listeria was present in 30% and 26% of the investigated soil and water samples, respectively. Generally, the most dominant species in soil and water samples were Listeria seeligeri, L. innocua, and L. ivanovii. The human- and animal-pathogenic L. monocytogenes was isolated exclusively from 6% soil samples in regions A (mountainous region) and B (meadow). Distinct ecological preferences were observed for L. seeligeri and L. ivanovii, which were more often isolated from wildlife reserve region C (Lake Neusiedl) and from sites in proximity to wild and domestic ruminants (region A). The higher L. monocytogenes detection and antibiotic resistance rates in regions A and B could be explained by the proximity to agricultural land and urban environment. L. monocytogenes multilocus sequence typing corroborated this evidence since sequence type 37 (ST37), ST91, ST101, and ST517 were repeatedly isolated from regions A and B over several months. A higher L. monocytogenes detection and strain variability was observed during flooding of the river Schwarza (region A) and Danube (region B) in September 2007, indicating dispersion via watercourses., (Copyright © 2014, American Society for Microbiology. All Rights Reserved.)

Cross-contamination via equipment and the food-processing environment has been implicated as the main cause of Listeria monocytogenes transmission. The aim of this study, therefore, was to determine the occurrence and potential persistence of L. monocytogenes in 19 European cheese-processing facilities. A sampling approach in 2007-2008 included, respectively, 11 and two industrial cheese producers in Austria and the Czech Republic, as well as six Irish on-farm cheese producers. From some of the producers, isolates were available from sampling before 2007. All isolates from both periods were included in a strain collection consisting of 226 L. monocytogenes isolates, which were then typed by serotyping and pulsed-field gel electrophoresis (PFGE). In addition, metabolic fingerprints from a subset of isolates were obtained by means of Fourier-transform infrared (FTIR) spectroscopy. PFGE typing showed that six processing environments were colonized with seven persistent PFGE types of L. monocytogenes. Multilocus sequence typing undertaken on representatives of the seven persisting PFGE types grouped them into distinct clades on the basis of country and origin; however, two persistent strains from an Austrian and an Irish food processor were shown to be clonal. It was concluded that despite the fact that elaborate Hazard Analysis and Critical Control Point concepts and cleaning programs are applied, persistent occurrence of L. monocytogenes can take place during cheese making. L. monocytogenes sanitation programs could be strengthened by including rapid analytical tools, such as FTIR, which allow prescreening of potentially persistent L. monocytogenes contaminants.

We report on a coinfection of Mycobacterium avium subsp. avium and Salmonella enterica serotype Typhimurium var. Copenhagen phage type DT2 in pigeons from one flock, from which squabs were occasionally consumed by humans. Triplex quantitative real-time PCR and culture methods were used for M. a. avium detection in livers and culture method was used for the detection of Salmonella sp. in samples of liver and caecum of 33 examined birds. M. a. avium was detected in a total of 31 (93.9%) and Salmonella Typhimurium in a total of 11 (33.3%) pigeons. Coinfection with both pathogens was found in 10 (30.3%), infection with Salmonella Typhimurium alone in 1 (3.0%), and infection with M. a. avium alone in 21 (63.7%) pigeons. Neither pathogen was detected in one pigeon. There was no difference in clinical symptoms exhibited by pigeons infected by M. a. avium and/or Salmonella Typhimurium. All Salmonella Typhimurium isolates were sensitive to all 15 antimicrobials tested. According to these results we emphasize good heat treatment of consumed squabs.

A case of fatal salmonellosis in a Eurasian eagle-owl (Bubo bubo) from Bursa Province (northwestern Turkey) is described. The organs of the bird were examined histopathologically and microbiologically. Macroscopic and microscopic findings were consistent with a Salmonella infection. Salmonella enterica subspecies enterica serovar Enteritidis (S. Enteritidis) phage type (PT) 21b was isolated from the liver and spleen in pure culture and from the intestine. The isolate was susceptible to amoxycillin/clavulanic acid, ampicillin, chloramphenicol, gentamicin, kanamycin, tetracycline, and trimethoprim/sulphamethoxazole. This is the first report of an isolation of salmonellae from a wild bird species from Turkey and the first time S. Enteritidis PT21b has been reported from Turkey.

As part of a standardization project, an interlaboratory trial including 15 laboratories from 13 European countries was conducted to evaluate the performance of a noproprietary polymerase chain reaction (PCR)-based method for the detection of Salmonella on artificially contaminated chicken rinse and pig swab samples. The 3 levels were 1-10, 10-100, and 100-1000 colony-forming units (CFU)/100 mL. Sample preparations, including inoculation and pre-enrichment in buffered peptone water (BPW), were performed centrally in a German laboratory; the pre-PCR sample preparation (by a resin-based method) and PCR assay (gel electrophoresis detection) were performed by the receiving laboratories. Aliquots of BPW enrichment cultures were sent to the participants, who analyzed them using a thermal lysis procedure followed by a validated Salmonella-specific PCR assay. The results were reported as negative or positive. Outlier results caused, for example, by gross departures from the experimental protocol, were omitted from the analysis. For both the chicken rinse and the pig swab samples, the diagnostic sensitivity was 100%, with 100% accordance (repeatability) and concordance (reproducibility). The diagnostic specificity was 80.1% (with 85.7% accordance and 67.5% concordance) for chicken rinse, and 91.7% (with 100% accordance and 83.3% concordance) for pig swab. Thus, the interlaboratory variation due to personnel, reagents, thermal cyclers, etc., did not affect the performance of the method, which will be proposed as part of a developing international PCR standard.

Bacterial retron reverse transcriptases are unusual enzymes which utilise the same RNA molecule as a template and also as a primer for initiation of the reverse transcription. Except for their relatively frequent presence in Myxococcus spp., they are considered as quite rare proteins. However, in this study we proved that retron reverse transcriptase is frequently found in certain serovars of Salmonella enterica. Using polymerase chain reaction (PCR), in strains of serovar Typhimurium, the rrtT (retron reverse transcriptase Typhimurium) gene was detected in 158 out of 175 tested field strains. On the other hand, in none of the 18 tested serovar Enteritidis strains the rrtT was detected in their genome. Detailed computer analysis allowed us to predict the sequence of msDNA and to propose that the final msDNA is free of any RNA. Furthermore, we predict that there are at least three different classes of retron reverse transcriptases.

Salmonella enterica serovar Enteritidis (S. Enteritidis) possesses plasmids of different sizes and roles. Besides the serovar-specific virulence plasmid present in most field strains, S. Enteritidis can harbour plasmids of low molecular mass whose biological role is poorly understood. We therefore sequenced plasmid pC present in S. Enteritidis strains belonging to phage type PT14b. The size of plasmid was determined to be 5,269 bp and it was predicted to encode four open reading frames (ORFs). The first two ORFs were found (initial 3,230 bp) to be highly homologous to rom and mbeA genes of ColE1 plasmid of Escherichia coli. Proteins encoded by the other two ORFs were 99% homologous to a restriction methylase and restriction endonuclease encoded by plasmid pECO29 of a field strain of E. coli. Using insertional mutagenesis we confirmed experimentally that the plasmid pC-encoded restriction modification system was functional and could explain the high resistance of S. Enteritidis PT14b strains to phage infection.

The Czech Republic is a country in central Europe with a population of about 10 million inhabitants. Salmonellosis is the most commonly reported infectious intestinal disease. Until 1989 about 10 000 cases were reported each year, and similar numbers of S

Computer-assisted restriction endonuclease analysis of plasmid DNA in field strains of Salmonella enterica serovar Enteritidis (S. enteritidis) is described. The procedure consists of plasmid DNA purification, its digestion with restriction endonuclease TaqI, electrophoresis, charge-coupled device camera scanning of the gels, and an analysis of the restriction patterns with the software Gel Manager. The system allowed us to analyse, in detail, results of plasmid profiling in more than 600 field strains of S. enteritidis. In addition to plasmid-free and virulence plasmid only containing strains, 15 additional plasmid types were detected. All the images and detailed protocols are available at the Web site http://www.clark.cz/vri/salmon.htm.