Serum survival and plasmid possession by strains of Salmonella enteritidis, Salm. typhimurium and Salm. virchow

Strains of Salmonella enteritidis, Salm. typhimurium and Salm. virchow , carrying different numbers of plasmids, were examined for the ability to multiply in sera. Viable counts were performed to monitor the kinetics of growth of bacteria when in human, chicken and turkey sera. The presence of plasmids in Salm. enteritidis, Salm. typhimurium and Salm. virchow reduced considerably the ability of strains of these serotypes to multiply in serum. SDS-PAGE was used to show that growth of Salm. enteritidis in serum did not involve changes in outer membrane proteins or lipopolysaccharide. It was concluded that the carriage of plasmids may be disadvantageous for the survival in serum of certain common salmonella serotypes.     

Salmonella in surface waters of central New York state.

Six tributary streams and southern Cayuga Lake in central New York state were sampled for the presence of Salmonella on swabs immersed for 4 days. Of a total of 322 swabs, 39% yielded salmonellae. Swabs were cultured in tetrathionate enrichment at 41.5 degrees C. Isolations were made from brilliant green agar. Salmonellae were isolated from many sites on the streams and from some lake sites. Twenty-five serotypes (11 somatic antigen groups) and a distinct biotype of S. typhimurium (H2S negative) were found. Most frequent isolates, in order of decreasing occurrence, were S. typhimurium, S. thompson, S. oranienburg, and S. enteritidis. Several uncommon isolates also appeared. When tested for mouse infectivity, the isolates generally showed little or no virulence. The incidence of clinical salmonellosis among humans was low in the area and the variety of serotypes had not been noted among cattle. The presence of Salmonella in waters ranging in classification from potable to agricultural and industrial indicated the existence of a low level and undefined reservoirs of the bacteria in the region.     

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.     

Salmonella in horses: a source of contamination of horsemeat in a packing plant under federal inspection.

Cecal samples from 270 slaughter horses revealed that 41 samples (15.1%) contained Salmonella. Of 233 horsemeat samples tested, Salmonella was isolated from 62 samples, or 26.6%. Only 2 of 158 human stool specimens from the plant workers revealed Salmonella. Predominant serotypes isolated from the horsemeat were Salmonella enteritidis Good and Anatum, whereas the serotypes Agona and Derby predominated the horse cecal isolates. Preliminary data indicate that the high percentage of meat contamination is surface contamination due to poor slaughtering technique.     

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.     

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.     

Rapid identification of Salmonella typhimurium, S. enteritidis and S. virchow isolates by polymerase chain reaction based fingerprinting methods.

In this study we used and evaluated three rapid molecular typing methods for the identification of three frequent, clinically significant Salmonella serovars on the basis of the ease, simplicity and reproducibility of the chosen methods. We determined the genetic diversity among several isolates of Salmonella enteritidis, S. typhimiurium and S. virchow, and compared them with other enterobacteria by using the repetitive extragenic palindromic (REP) sequences, the enterobacterial repetitive intergenic consensus (ERIC) sequences, and the 16S-23S rDNA intergenic spacer region (ITS 1). The objective was to evaluate their potential application to discriminate among members of the species Salmonella enterica subspecies enterica using the genetic diversity of the group found by genomic fingerprinting. The three different serovars of Salmonella studied gave reproducible and distinguishable profiles using whichever of the above mentioned polymerase chain reaction (PCR) methods assayed. The conserved patterns in each serovar allowed for easy differentiation from other serovars of Salmonella.     

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.     

RAPID IDENTIFICATION AND SEROTYPING OF SALMONELLA ENTERITIDIS

A latex agglutination kit for S. enteritidis was evaluated on 155 field isolates from 29 serotypes from Denmark, All but one of the S. enteritidis isolates were correctly identified by the kit, and none of the isolates of other serotypes tested were identified as S. enteritidis. The results indicate a very high degree of specificity and sensitivity for the SEF14 monoclonal antibody, which forms the basis of the test.     

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.     

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。     

Selection of methods of detecting lactose-fermenting Salmonella strains and evaluating their usefulness for diagnostic studies

Salmonella rods of subspecies I, lactose-fermenting were first isolated in Poland in 1980. They were isolated from a plus sample taken from a brain abscess of a child. Next strains were isolated from faeces of newborn and hospitalized children. Growth characteristic of colonies of lactose-fermenting Salmonella strains on selective-differentiating media (Mac Conkey's Levine, SS, So?tys) recommended for inoculation of clinical material resembled Escherichia coli. So far these type of colonies were omitted in diagnostic examinations. Lactose-fermenting variants showed on Bismuth sulfate agar "Difco" (WB) typical for Salmonella growth pattern. They grew on this medium after 48 hr of incubation in a form of black, medium sized colonies, with some metallic brilliance and characteristic blackening of the medium undercolonies. Precise knowledge of biochemical properties of lactose-fermenting Salmonella allows to supplement so far used diagnostic scheme with additional tests permitting differentiation of lactose-fermenting variants of Salmonella from the other members of Enterobacteriaceae family. Taking into consideration biochemical variants in diagnostic procedure i.e. lactose-fermenting Salmonella, allowedns to isolate in the years 1983-1985 lactose-positive strains in 1305 out of 2773 (47%) individuals positive for S. agona. In 1987, 246 persons (28.3%) out of 869 with lactose-fermenting Salmonella of various serotypes were simultaneously infected with lactose-negative variant. Lactose-fermenting strains of Salmonella belonged most frequently to the following genera: S. agona, S. enteritidis, S. oranienburg, S. typhimurium, and S. goldcoast. It was found that the modified diagnostic procedure makes possible the isolation and the identification of lactose-positive varians of Salmonella.     

Etiological structure of salmonellosis and the serotype passage of salmonellae isolated in separate regions of the USSR in 1980-1982

At the period of 1980-1982 the isolation of salmonellae belonging to 394 serovars was registered in the USSR. Of these, 116 Salmonella serovars were registered in the USSR for the first time. 12 dominating serovars constituted 83.1% of salmonellae isolated from humans, 99% of salmonellae isolated from animals and 70% of all salmonellae isolated from different environmental objects. S. typhimurium was the predominant serovar, found to determine 50% of cases of Salmonella infection. The isolation rate of S. infantis and S. virchow was shown to increase. The existence of definite ecological relationships between infective agents isolated from different sources was established.     

Antagonistic effects of intestinal Lactobacillus isolates on pathogens of chicken

L.Z. JIN, Y.W. HO, N. ABDULLAH, M.A. ALI AND S. JALALUDIN. 1996. Twelve Lactobacillus strains isolated from chicken intestine, which demonstrated a strong and moderate capacity to adhere to the ileal epithelial cells in vitro , were used to investigate their inhibitory ability against five strains of salmonella, i.e. Salmonella enteritidis 935/79, Salm. pullorum, Salm. typhimurium, Salm. blockley and Salm. enteritidis 94/448, and three serotypes of Escherichia coli , viz. E. coli O1 : K1, O2 : K1 and O78 : K80. The results showed that all the 12 Lactobacillus isolates were able to inhibit the growth of the five strains of salmonella, and the three strains of E. coli in varying degrees. Generally, they were more effective in inhibiting the growth of salmonella than E. coli . Inhibition of the pathogenic bacteria was probably due to the production of organic acids by the Lactobacillus isolates.     

Immunomagnetic separation as an alternative to enrichment broths for Salmonella detection

One hundred and twenty foodstuffs were tested for the enrichment of Salmonella species by immunoseparation. The foodstuffs covered six groups: raw chicken, prawns, skimmed milk powder, herbs and spices, cocoa powder and animal feed. Half of the food samples were spiked with one Salmonella species: Salm. ealing, Salm. enteritidis, Salm. give, Salm. typhimurium or Salm. virchow . Comparison of Salmonella recovery with standard methods (selenite cystine broth, tetrathionate broth and Rappaport-Vassiliadis broth) was carried out. Immunoseparation gave similar numbers of true positives to the standard enrichment methods in a short time period. Only immunoseparation isolated Salmonella species from spiked garlic granules demonstrating the possible recovery of sublethally injured cells.     

Molecular phylogenetic typing of pandemic isolates of Salmonella enteritidis

Salmonella enteritidis is now the most common Salmonella serovar in many countries. We have used cloned DNA probes to analyze genome interrelationships between strains chosen to represent the current S. enteritidis pandemic, and included designated type strains of the seven subspecies of Salmonella in order to compare the levels of discrimination of probes. DNA sequence divergence and rearrangements were analyzed in and around the rfa, fim and umuDC loci, and around insertion sites of the Salmonella-specific DNA insertion element, IS200. The S. enteritidis isolates showed a high degree of genome homogeneity. Chromosomal genetic loci exhibited characteristic DNA sequence divergence between subspecies of Salmonella, but no intraserovar divergence or difference with the subspecies I type strain was observed for S. enteritidis. The locus umuDC was not found in S. enteritidis. S. enteritidis contains a conserved and a variable site of insertion of insertion sequence IS200 and the analysis of DNA rearrangements around the second of these sites showed that three distinct evolutionary lines or races exist within pandemic isolates associated with human gasteroenteritis. IS200 profiles of a range of U.K. isolates of the epidemic phage type PT4 showed that all belonged to a single clonal line.     

A comparison of Salmonella serotypes isolated from New Zealand sea lions and feral pigs on the Auckland Islands by pulsed-field gel electrophoresis

The Salmonella serotypes S. Cerro and S. Newport were isolated from New Zealand sea lions (Phocarctos hookeri) and feral pigs on the Auckland Islands in the New Zealand subantarctic region. The isolates were typed by pulsed-field gel electrophoresis using Xba1 as the restriction enzyme. The isolates were indistinguishable, which suggests that Salmonella infection cycles between sea lions and pigs in this environment. Apart from a previous isolation from a single New Zealand fur seal (Arctocephalus forsteri), S. Newport has not been recorded in any animals from New Zealand, but it is associated with gastroenteritis in humans. Contamination of the marine environment by human waste is a possible source of infection for marine mammals and warrants further investigation.     

Prevalence of Serotypes of Salmonella

The distribution of species and serotypes of Salmonella among 2,498 cultures which were isolated in the United States and its territories is presented. These isolates were received for examination during the 12-month period between October 1, 1966 and September 30, 1967. These and other data obtained from the Salmonella Surveillance Summaries for the past five years indicate that a relatively small number of species and serotypes of Salmonella are regularly isolated from diagnostic specimens. Of approximately 1,300 presently known Salmonella species and serotypes, 33 account for almost 90% of the isolates reported from humans and approximately 80% of the isolates from nonhuman sources. The 50 most prevalent species and serotypes account for 97% of the isolates from humans. An abbreviated antigenic schema based on these 50 species and serotypes of Salmonella, in conjunction with adequate biochemical tests, permits complete bacteriological characterization of the common Salmonella     

Typing of Salmonella enteritidis of different phage types of PCR fingerprinting

Fifty-nine isolates of Salmonella spp. were typed by PCR fingerprinting using three single primers: ERIC2, M13 and OPS-19. First, their discrimination power in a group of nine different serotypes were studied and considerable differences in the band patterns were obtained. Further, a panel of 51 isolates of Salmonella enteritidis with eight different phage types were analysed with the three primers. The discriminating power increased by combining the patterns of the three primers, and in this case it was possible to distinguish between some phage types of Salm. enteritidis , but not all of them were differentiated.     

Aquarium pets as a source of antibiotic-resistant salmonellae.

Thirteen serotypes of Salmonella isolated from imported ornamental aquarium frogs, snails, and their waters were shown to be multi-drug-resistant. Among the resistances exhibited were resistance to gentamicin, sulfamethoxazole-trimethoprim, cephalothin, and nalidixic acid. Frog isolates displayed eight different patterns and snails isolates had two different resistance patterns. The most common serotype, Salmonella typhimurium, was resistant to 18 antibacterials while other salmonellae were resistant to 9 to 16 antibacterials. Resistances in S. typhimurium and S. bovis-morbificans were conjugative and a number of R plasmids participated in the resistance. The plasmid-mediated resistance in S. typhimurium was stable and the levels of resistance conferred were markedly higher than in the other salmonellae tested. Resistance of other serotypes was non-conjugative and resistance to the beta-lactam antibiotics was unstable.