Salmonella species isolated from animal feed in Iraq.

Of 700 animal feed samples, 32 (4.5%) harbored Salmonella. The highest percentage of contamination was found in sheep feed and local protein. A total of 17 Salmonella serotypes were identified. The most frequent serotypes were Salmonella meleagridis. S. bornum, S. montevideo, and S. drypool. S. bornum was isolated for the first time in Iraq and from both local feed and its ingredients. The common somatic group found was that of Salmonella group C; then came groups E, G, B, and D. Three serotypes (S. enteritidis, S. california, and S. muenchen) seemed to form a link of infection among feed, food, patients, and carriers.     

<Emphasis Type="Italic">Salmonella</Emphasis> Isolated from Animals and Feed Production in Sweden Between 1993 and 1997

This paper presents Salmonella data from animals, feedstuffs and feed mills in Sweden between 1993 and 1997. During that period, 555 isolates were recorded from animals, representing 87 serotypes. Of those, 30 serotypes were found in animals in Sweden for the first time. The majority of all isolates from animals were S. Typhimurium (n = 91), followed by S. Dublin (n = 82). There were 115 isolates from cattle, 21 from broilers, 56 from layers and 18 from swine. The majority of these isolates were from outbreaks, although some were isolated at the surveillance at slaughterhouses. The number of isolates from the feed industry was similar to that of the previous 5-year period. Most of those findings were from dust and scrapings from feed mills, in accordance with the HACCP programme in the feed control programme. It can be concluded that the occurrence of Salmonella in animals and in the feed production in Sweden remained favourable during 1993–97.     

辽宁食源性沙门菌血清型、 耐药谱及PFGE分型特征

目的分析辽宁食源性沙门菌血清型、耐药谱及脉冲场凝胶电泳(PFGE)型别,探讨辽宁沙门菌污染的同源性,为食源性疾病溯源和预警提供基础。方法对辽宁省2015年食品中、食源性疾病中分离的41株沙门菌进行血清学分型、耐药试验、PFGE分子分型,采用Bio Numerics version 6.6软件分析,比较同源性。结果 41株菌分为15个血清型,居前三位的是15株肠炎沙门菌、5株德尔卑沙门菌、5株姆班达卡沙门菌(辽宁省内少见血清型);对41株菌进行15种抗生素的耐药试验,对单一一种抗生素的耐药率为100.0%,其中红霉素97.6%,萘啶酸61.0%,氨苄西林53.7%;41株菌共分为18种PFGE带型,带型分布分散,只有两种优势,一种带型包含20株菌,有14株肠炎沙门菌,6株其他沙门菌,相似度为92.7%~100%;另一种包含5株菌,4株姆班达卡沙门菌,1株鼠伤寒沙门菌,相似度为96.6%~100.0%。结论辽宁省食源性沙门菌的血清型以肠炎沙门菌为主,生肉制品是其主要污染来源;血清型与PFGE图谱带型分布广泛,相同血清型沙门菌的PFGE带型聚集成簇、菌株具有高度同源性;相同PFGE型别的菌株耐药谱一致或相似;沙门菌的耐药情况较严重。     

Prevalence of Salmonella serotypes in environmental waters and their relationships with indicator organisms

The incidence of serotypes of Salmonella in three types of environmental water (sea, river and fresh reservoirs) from north-east Spain was investigated. The study was performed at specific sampling locations during the summer for a period of five years (1992–1996). A total of 823 strains were isolated and 55 different serotypes were identified, 42 were recovered from sea water, 32 from river water and 12 from freshwater reservoirs. The most frequently isolated serotypes coincided with those involved in clinical cases in the area studied. Salmonella enteritidis was the most common (111 isolates), it was found in all types of water, although most predominantly in sea water (16.1% of the isolates). This serotype, together with S. hadar, significantly increased in frequency during the five year study period. The most frequent serotypes in river water and freshwater reservoirs were S. virchow (9.5%) and S. mikawasima (23.8%) respectively. Significant differences were assessed in the indicator organism densities between the samples with serotypes of clinical significance (S. enteritidis, S. infantis, S. typhimurium, S. virchow and S. paratyphi B) and those without clinical significance. Therefore their presence in all environmental waters may be of epidemiological significance.     

Roles of diet and the acid tolerance response in survival of common Salmonella serotypes in feces of finishing pigs

The persistence of Salmonella in the environment is an important factor influencing the transmission of infection in pig production. This study evaluated the effects of acid tolerance response (ATR), organic acid supplementation, and physical properties of feed on the survival of a five-strain Salmonella mixture in porcine feces held at 4 and 22°C for 88 days. Acid-adapted or non-acid-adapted nalidixic acid-resistant Salmonella strains were used to inoculate feces of pigs fed four different diets, which consisted of a nonpelleted, finely ground meal feed or a finely ground, pelleted feed that was left unsupplemented or was supplemented with K-diformate. Organic acid supplementation and physical properties of feed markedly influenced Salmonella survival, but the effects were highly dependent on storage temperature; survival was unaffected by ATR. The most pronounced effects were observed at 22°C, a temperature similar to that of finishing pig houses. The supplementation of meal diets with K-diformate significantly reduced the duration of survival (P < 0.1) and increased rates of decline (P < 0.0001) of salmonellae in feces compared to survival in feces of pigs fed unsupplemented meal. The pelleting of feed, compared to feeding meal, significantly reduced (P < 0.1) the duration of survival in feces held at 22°C. Only minor effects of feed form and acid supplementation on survivor numbers were observed at 4°C. Differences in the fecal survival of Salmonella could not be related to diet-induced changes in fecal physiochemical parameters. The predominant survival of S. enterica serovar Typhimurium DT193 and serotype 4,[5],12:i:- in porcine feces demonstrates the superior ability of these serotypes to survive in this environment. Fecal survival and transmission of Salmonella in pig herds may be reduced by dietary approaches, but effects are highly dependent on environmental temperature.     

Use of Fourier transform infrared spectra of crude bacterial lipopolysaccharides and chemometrics for differentiation of Salmonella enterica serotypes

AIMS: To evaluate Fourier transform infrared spectroscopy (FTIR) and chemometrics for differentiating intact cells and crude lipopolysaccharide (LPS) extracts from Salmonella serotypes. METHODS AND RESULTS: Intact cells and crude LPS extracts from six different Salmonella enterica serotypes (Typhimurium, Enteritidis, Thomasville, Brandenburg, Hadar and Seftenberg) were used. The crude Salmonella LPS extracts were visualized using deoxycholic acid-polyacrylamide gel electrophoresis (DOC-PAGE) and appeared heterogeneous on the gel with two exceptions: S. Enteritidis and S. Brandenburg, and S. Thomasville and S. Seftenberg. Canonical variate analysis (CVA) of spectra of crude LPS extracts provided 100% correct classification. CVA of spectra of intact cells was not useful for classifying the Salmonella serotypes, having only 47 and 50% correct classifications in the 1200-900 and 4000-700 cm(-1) regions respectively. These data were confirmed by greater Mahalanobis distances between crude LPS spectra than intact cell spectra. CONCLUSIONS: CVA of FTIR spectra of crude LPS extracts from Salmonella serotypes provided a 100% correct serotype classification. SIGNIFICANCE AND IMPACT OF THE STUDY: This study suggests that the FTIR analytical procedure provides chemical detail as well as a better separation of Salmonella serotypes using spectra of crude LPS extracts than analysis using DOC-PAGE.     

The ecology of Salmonella serotypes in a wild marsupial (the quokka Setonix brachyurus) in a disturbed environment

Previous studies have shown that the quokka (Setonix brachyurus: Marsupialia) experiences a very extensive proliferation of Salmonella infections on Rottnest Is. (Western Australia) in association with seasonal starvation in a disturbed environment. The study reported here examined the distribution of the serotypes involved, the interaction of Salmonella with other hosts, and the resulting environmental contamination. In the quokka, the serotypes were found to be significantly non-random in their distribution between areas (regardless of a seasonal cycle of infection rate in some areas) and between seasons. No one serotype showed a particular affinity for the quokka in the most adverse season. Study of the largest deviations showed that they could have been due to local amplification of particular serotypes in other hosts. It was not generally possible to distinguish the native and exotic serotypes as groups, and each serotype needed to be studied in terms of its own ecology. Environmental contamination is extensive due to proliferation of Salmonella in quokkas, but the interactions with other hosts were found to be important in determining the local distribution of serotypes. The results of this study are discussed in terms of the significance of the distribution of Salmonella in natural and disturbed areas in Western Australia, and of management of the problems created by proliferation of Salmonella in the Rottnest Is. quokka.     

Salmonella enteritidis temperature-sensitive mutants protect mice against challenge with virulent Salmonella strains of different serotypes

The protection conferred by temperature-sensitive mutants of Salmonella enteritidis against different wild-type Salmonella serotypes was investigated. Oral immunization with the single temperature-sensitive mutant E/1/3 or with a temperature-sensitive thymine-requiring double mutant (E/1/3T) conferred: (i) significant protection against the homologous wild-type Salmonella strains; (ii) significant cross-protection toward high challenge doses of S. typhimurium. Significant antibody levels against homologous lipopolysaccharide and against homologous and heterologous protein antigens were detected in sera from immunized mice. Moreover, a wide range of protein antigens from different Salmonella O serotypes were recognized by sera from immunized animals. Besides, primed lymphocytes from E/1/3 immunized mice recognized Salmonella antigens from different serotypes. Taken together, these results indicate that temperature-sensitive mutants of S. enteritidis are good candidates for the construction of live vaccines against Salmonella.     

Population structure of Salmonella investigated by amplified fragment length polymorphism

AIMS: This study was undertaken to investigate the usefulness of amplified fragment length polymorphism (AFLP) in determining the population structure of Salmonella. METHODS AND RESULTS: A total of 89 strains were subjected to AFLP analysis using the enzymes BglII and BspDI, a combination that is novel in Salmonella. Both species S. bongori and S. enterica and all subsp. of S. enterica were represented with emphasis on S. enterica subsp. enterica using a local strain collection and strains from the Salmonella Reference Collection B (SARB). The amplified fragments were used in a band-based cluster analysis. The tree resulting from the subgroup analysis clearly separated all subgroups with high bootstrap values with the species S. bongori being the most distantly related of the subgroups. The tree resulting from the analysis of the SARB collection showed that some serotypes are very clonal whereas others are highly divergent. CONCLUSIONS: AFLP clearly clustered strains representing the subgroups of Salmonella together with high bootstrap values and the serotypes of subspecies enterica were divided into polyphyletic or monophyletic types corresponding well with multilocus enzyme electrophoresis (MLEE) and sequence-based studies of the population structure in Salmonella. SIGNIFICANCE AND IMPACT OF THE STUDY: AFLP with the enzyme combination BglII and BspDI allows discrimination of individual strains and provides evidence for the usefulness of AFLP in studies of population structure in Salmonella.     

Presence of Salmonella as a risk to public health in the Caribbean zone of Colombia

Salmonella is frequently involved in diarrhoeal disease throughout the world and is disseminated mainly by food, polluted waters or infected food-handlers. In Colombia, the serotypes of Salmonella and their distribution in food have not been characterized. Therefore, the objective was to establish the epidemiology of Salmonella in the Caribbean zone. Six hundred thirty-six samples were obtained in fast food outlets located in city squares or markets of Barranquilla (n=245), Montería (n=222), Sincelejo (n=87) and Cartagena (n=82). Salmonella was isolated by the conventional methods recommended by the United States Food and Drug Administration. Briefly, 25 g of each sample was inoculated in 225 ml of broth. Twenty-four hours later, a 1 ml aliquot was inoculated onto selective media for Salmonella. Suspicious colonies were identified by conventional biochemical tests and confirmed by conventional serology for Salmonella detection. Forty-seven Salmonella serotypes were isolated from meat (40%), sausage (25%), cheese (13%), pig (13%), chicken (4.2%) and egg 'arepas' (4.2%). The serologic characterization indicated the following serotypes: S. Anatum (26%), S. Newport (13%), S. Typhimurium (9%), S. Gaminara (9%) and S. Uganda (9%). No statistically significant Salmonella isolations among 4 socioeconomic categories were observed (p=0.05). However, differences were observed when rates were compared for Salmonella by food type for socioeconomic categories 1, 2 and 3 (p<0.05), categories 2 and 3 did not show differences between them (p>0.05).     

Multidrug resistance to antibacterial drugs of Salmonella enterica subsp. enterica strains isolated in Poland in the 1998-1999 period]

A total of 510 Salmonella enterica subsp. enterica strains representing 56 serotypes, isolated from human stool specimens during 1998-2000 in sanitary-epidemiological units in Poland were tested for their susceptibility by a standard disk diffusion method for: ampicillin, cefotaxime, chloramphenicol, tetracycline, streptomycin, gentamicin, kanamycin, nalidixic acid, ciprofloxacin, furazolidone, cotrimoxazole, sulfonamides and trimethoprim. For 201 of the investigated strains, belonging to 5 most common isolated serotypes (S. Enteritidis, S. Typhimurium, S. Hadar, S. Infantis and S. Virchow) the minimal inhibitory concentrations (MICs) for the aforementioned antibiotics, as well as for amoxicillin with clavulanian were determined. Selected strains were screened for production extended spectrum b-lactamases (ESBLs). It was observed that 42.9% of Salmonella enterica subsp. enterica strains were resistant to 2 or more antibiotics, with the highest prevalence of MDR strains among serotypes Typhimurium, Hadar and Virchow. Resistance to ampicillin, streptomycin, tetracycline, nalidixic acid, furazolidone and sulphonamides was observed most frequently. Over 93% of S. Virchow strains were resistant to furazolidone. No strains resistant to ciprofloxacin were detected according to the NCCLS guidelines, but 31.3% of isolates exhibiting reduced ciprofloxacin susceptibility (MICs ranging between 0.125 and 0.5 mg/l). Two strains S. Mbandaka and Salmonella group D (variant motility--) were resistant to cefotaxime and probably produced ESBL.     

Salmonella serotypes isolated from human enteric processes in Recife, Pernambuco, during 1978-1980

From 13,196 faecal cultures made in Recife-Pernambuco during the period from 1978 to 1980, 1,720 strains of Salmonella were isolated. Serological typing on 1,387 of the isolates recognized 63 serotypes, 73.18% of which belonged to group B. The prevalent serotypes adding up to 1,231 strains (88.75% of the total of the isolates) were: S. typhimurium, S. saint-paul, S. poona, S. derby, S. agona, S. newport, S. oranienburg, S. infantis, S. tshiongwe and S. ndolo.     

Loop-mediated isothermal amplification for the rapid detection of Salmonella

Loop-mediated isothermal amplification (LAMP) assay detected Salmonella within 60 min. The 220 strains of 39 serotypes of Salmonella subsp. enterica and 7 strains of Salmonella enterica subsp. arizonae were amplified, but not 62 strains of 23 bacterial species other than Salmonella. The sensitivity of the LAMP assay was found to be >2.2 cfu/test tube using nine serotypes. The specificity was similar to that of a PCR assay, but the sensitivity of LAMP was greater. Both fluorescence and turbidity were able to detect the products in the LAMP assay. S. enteritidis in a liquid egg sample artificially inoculated with the organism was detected by the LAMP assay at 2.8 cfu/test tube, although negative by PCR assay. These results indicate that the LAMP assay is a rapid, specific and sensitive detection method for Salmonella.     

Prevalence, enumeration, serotypes, and antimicrobial resistance phenotypes of salmonella enterica isolates from carcasses at two large United States pork processing plants

The objective of this study was to characterize Salmonella enterica contamination on carcasses in two large U.S. commercial pork processing plants. The carcasses were sampled at three points, before scalding (prescald), after dehairing/polishing but before evisceration (preevisceration), and after chilling (chilled final). The overall prevalences of Salmonella on carcasses at these three sampling points, prescald, preevisceration, and after chilling, were 91.2%, 19.1%, and 3.7%, respectively. At one of the two plants, the prevalence of Salmonella was significantly higher (P < 0.01) for each of the carcass sampling points. The prevalences of carcasses with enumerable Salmonella at prescald, preevisceration, and after chilling were 37.7%, 4.8%, and 0.6%, respectively. A total of 294 prescald carcasses had Salmonella loads of >1.9 log CFU/100 cm(2), but these carcasses were not equally distributed between the two plants, as 234 occurred at the plant with higher Salmonella prevalences. Forty-one serotypes were identified on prescald carcasses with Salmonella enterica serotypes Derby, Typhimurium, and Anatum predominating. S. enterica serotypes Typhimurium and London were the most common of the 24 serotypes isolated from preevisceration carcasses. The Salmonella serotypes Johannesburg and Typhimurium were the most frequently isolated serotypes of the 9 serotypes identified from chilled final carcasses. Antimicrobial susceptibility was determined for selected isolates from each carcass sampling point. Multiple drug resistance (MDR), defined as resistance to three or more classes of antimicrobial agents, was identified for 71.2%, 47.8%, and 77.5% of the tested isolates from prescald, preevisceration, and chilled final carcasses, respectively. The results of this study indicate that the interventions used by pork processing plants greatly reduce the prevalence of Salmonella on carcasses, but MDR Salmonella was isolated from 3.2% of the final carcasses sampled.     

Salmonella Isolated from Animals and Feedstuffs in Sweden during 1988-1992

The present paper surveys the number of Salmonella isolations in animals and feedstuffs in Sweden during 1988–1992. It is the eighth in a series of reports published by the National Veterinary Institute (NVI) since 1949. During the period referred to, 602 outbreaks of Salmonella were reported in animals, both domestic and wild. Compared with the previous 5-year period there was a 20% reduction in the number of outbreaks (760). Fifty-six different serotypes were reported, 19 of which had never been isolated in any animal in Sweden previously. A temporary increase in the number of outbreaks in poultry was seen in 1991 following an extended sampling before slaughter of layers. A remarkably high prevalence (38%) of Salmonella was observed in snakes in the wild. In 1990, the end-point testing of feeds was replaced by an approach based on HACCP (Hazard Analysis Critical Control Point) principles for the monitoring of feed mills. Significantly higher number of Salmonella positive samples were found by using this technique compared with the previous analysis of finished feed. It is concluded that the adopted Salmonella control program has contributed to a reduced number of Salmonella outbreaks in animals in Sweden.     

Structure of salmonellal transmissive resistance to antibiotics]

The structure of transmissive resistance to antibiotics was studied in 1260 Salmonella strains of 57 serotypes and R-plasmid resistance was found in the representatives of 13 (31.6 per cent) serotypes. The transmissive resistance correlated with multiple resistance to 4--10 antibiotics. The rate of occurrence of the transmissive R-plasmids was markedly higher in the bipathogenic serotypes. The structure of the R-plasmid resistance was most pronounced and diverse in S. typhimurium. It was usually revealed simultaneously with registration of the hospital infection. The plasmid with the determinants of resistance to erythromycin and benzylpenicillin was found only in this serotype. The nature of resistance and spectrum of transmissive resistance to antibiotics in Salmonella may serve as an additional epidemiological feature of the strains.     

Diversity of Salmonella strains isolated from the aquatic environment as determined by serotyping and amplification of the ribosomal DNA spacer regions

Salmonella species are pathogenic bacteria often detected in sewage, freshwater, marine coastal water, and groundwater. Salmonella spp. can survive for long periods in natural waters, and the persistence of specific and epidemic strains is of great concern in public health. However, the diversity of species found in the natural environment remains unknown. The aim of this study was to investigate the diversity of Salmonella strains isolated from different natural aquatic systems within a Mediterranean coastal watershed (river, wastewater, and marine coastal areas). A total of 574 strains isolated from these natural environments were identified by both conventional serotyping and the ribosomal spacer-heteroduplex polymorphism (RS-HP) method (M. A. Jensen and N. Straus, PCR Methods Appl. 3:186-194, 1993). More than 40 different serotypes were found, and some serotypes probably mobilized from widespread animal-rearing activities were detected only during storm events. These serotypes may be good indicators of specific contamination sources. Furthermore, the RS-HP method based on the PCR amplification of the intergenic spacer region between the 16S and 23S rRNA genes can produce amplicon profiles allowing the discrimination of species at both serotype and intraserotype levels. This method represents a powerful tool that could be used for rapid typing of Salmonella isolates.     

One-step triplex high-resolution melting analysis for rapid identification and simultaneous subtyping of frequently isolated Salmonella serovars

Salmonellosis is one of the most important food-borne diseases worldwide. For outbreak investigation and infection control, accurate and fast subtyping methods are essential. A triplex gene-scanning assay was developed and evaluated for serotype-specific subtyping of Salmonella enterica isolates based on specific single-nucleotide polymorphisms in fragments of fljB, gyrB, and ycfQ. Simultaneous gene scanning of fljB, gyrB, and ycfQ by high-resolution melting-curve analysis of 417 Salmonella isolates comprising 46 different serotypes allowed the unequivocal, simple, and fast identification of 37 serotypes. Identical melting-curve profiles were obtained in some cases from Salmonella enterica serotype Enteritidis and Salmonella enterica serotype Dublin, in all cases from Salmonella enterica serotype Ohio and Salmonella enterica serotype Rissen, from Salmonella enterica serotype Mbandaka and Salmonella enterica serotype Kentucky, and from Salmonella enterica serotype Bredeney, Salmonella enterica serotype Give, and Salmonella enterica serotype Schwarzengrund. To differentiate the most frequent Salmonella serotype, Enteritidis, from some S. Dublin isolates, an additional single PCR assay was developed for specific identification of S. Enteritidis. The closed-tube triplex high-resolution melting-curve assay developed, in combination with an S. Enteritidis-specific PCR, represents an improved protocol for accurate, cost-effective, simple, and fast subtyping of 39 Salmonella serotypes. These 39 serotypes represent more than 94% of all human and more than 85% of all nonhuman Salmonella isolates (including isolates from veterinary, food, and environmental samples) obtained in the years 2008 and 2009 in Austria.     

Allele-specific PCR method based on rfbS sequence for distinguishing Salmonella gallinarum from Salmonella pullorum: serotype-specific rfbS sequence polymorphism

Cloning and sequence analysis of rfbS gene identified two polymorphic nucleotides, one at position 598 (Salmonella gallinarum-specific) and other at position 237 (Salmonella pullorum-specific). Based on S. gallinarum-specific nucleotide found at position 598, an allele-specific PCR method was developed for serotype-specific detection of S. gallinarum. This PCR method was able to discriminate pure cultures of S. gallinarum from S. pullorum and other Salmonella serotypes from serogroup D in less than 3 h. Serotype-specific detection of S. gallinarum was possible in less than 24 h when the PCR was applied on the presumptive Salmonella colonies obtained after overnight incubation of selective media plates streaked with the clinical material from diseased chickens. As little as 100 pg of genomic DNA could be detected with S. gallinarum-specific primers; no PCR product was detected in non-S. gallinarum serotypes of serogroup D and other closely related non-salmonella organisms. This rfbS allele-specific amplification assay is specific, reproducible and less time consuming than the standard bacteriological methods used to detect S. gallinarum and could be an effective molecular tool for rapid definitive diagnosis of fowl typhoid in the areas of endemicity where fowl typhoid infection exists.     

Antimicrobial resistance of Salmonella spp. from pigs at slaughter in Spain in 1993 and 2001

AIM: To compare the incidence of antimicrobial resistance among Salmonella serotypes isolated in a pig slaughterhouse in Zaragoza (Spain) during 1993 and 2001. METHODS AND RESULTS: A total of 168 isolates representing 10 serotypes were examined by disc diffusion method using 17 antibiotics. Data showed that the majority of the strains were resistant to streptomycin (97%), sulfadiazine (93.4%) and tetracycline (83.3%). A large proportion of the collection was multidrug resistant (MDR, resistance to four or more antibiotics) with a greater incidence in 2001. The findings imply an increasing incidence of MDR amongst S. Typhimurium, and all S. Typhimurium-definitive phage type (DT) 104 isolates were resistant to ampicillin, chloramphenicol, streptomycin, sulphonamide and tetracycline (R-ACSSuT). This resistance phenotype had spread among other phage and serotypes. Salmonella Ohio was also a MDR serotype and this is not a serotype normally associated with drug resistance. CONCLUSIONS: A large proportion of the strains were MDR and this showed that pork products could be a potential vehicle of MDR Salmonella food-borne infections. SIGNIFICANCE AND IMPACT OF THE STUDY: The findings may have significant public health consequences and could contribute to the development of useful practices aimed at limiting the transmission of MDR Salmonella serotypes through the food chain.