Evaluation of Trimethoprim-sulphamethoxazole Compound in Treatment of Salmonella Infections

Fifty patients suffering from infections caused by various salmonella species were treated with trimethoprim-sulphamethoxazole compound. Twenty-three had enteric fever and two were biliary carriers of Salmonella typhi. The other 25 suffered from infections caused by salmonella species other than S. typhi or S. paratyphi B. Twenty-one of the patients with enteric fever responded clinically to the drug, one failed treatment, and one died. Two patients suffering from typhoid fever relapsed and three temporarily excreted S. typhi in stools following treatment. One of the typhoid carriers was successfully treated. All patients with infections caused by salmonella species other than S. typhi or S. paratyphi B responded to treatment but 17 continued to excrete the organism in their stools after the course of trimethoprim-sulphamethoxazole compound. Four patients developed rashes during therapy and two became anaemic.     

Reference collection of strains of the Salmonella typhimurium complex from natural populations

A collection of 72 reference strains of the Salmonella typhimurium complex of clones recovered from a variety of hosts and environmental sources in diverse geographic locations has been established for use in studies of variation in natural populations. Included are strains of the serovars S. typhimurium, S. saintpaul, S. heidelberg, S. paratyphi B (including variety java) and S. muenchen. The strains, which have been characterized by enzyme electrophoresis for allelic variation in 24 chromosomal structural genes and represent 48 distinctive multilocus genotypes (electrophoretic types or ETs), exemplify the full range of genotypic variation in the S. typhimurium complex. Evolutionary genetic relationships among the ETs are indicated in a phylogenetic tree generated by the neighbour-joining method from a matrix of Nei's standard genetic distance.     

6种沙门菌单克隆抗体的制备和效能评价

目的：制备稳定、特异、高亲和性的分别针对甲型副伤寒沙门菌、乙型副伤寒沙门菌、丙型副伤寒沙门菌、肠炎沙门菌、伤寒沙门菌和猪霍乱沙门菌的单克隆抗体。方法：用甲醛灭活的菌液抗原免疫BALB／c小鼠,取脾细胞与SP2／0骨髓瘤细胞融合;用灭活的菌液包被酶标板,ELISA筛选阳性克隆株,建立细胞系;选取高效分泌杂交瘤细胞,常规制备腹水并纯化,进行单抗特异性与亲和性评价。结果：筛选得到分泌6种沙门菌相应单克隆抗体的杂交瘤细胞株,获得高亲和性单抗;所有单抗与大部分病原菌（包括7种沙门菌、3株志贺菌、2株李斯特菌、4株致病性大肠杆菌、2株霍乱弧菌）无交叉反应,但由于同类型O抗原的广泛分布,抗乙型副伤寒沙门菌单抗与鼠伤寒沙门菌、抗伤寒沙门菌单抗与肠炎沙门菌有明显的交叉反应。结论：沙门菌单抗的制备,为感染性腹泻的监测、诊断奠定了基础。     

The chromosome of Salmonella paratyphi A is inverted by recombination between rrnH and rrnG.

Salmonella paratyphi A, a human-adapted bacterial pathogen, causes paratyphoid enteric fever. We established the genome map of strain ATCC 9150 by the use of four endonucleases, XbaI, I-CeuI, AvrII (= BlnI), and SpeI, which generated 27, 7, 19, and 38 fragments, respectively; the sum of the fragments in each case indicates a genome size of ca. 4,600 kb. With phage P22, we transduced Tn10 insertions in known genes from Salmonella typhimurium LT2 to S. paratyphi A ATCC 9150 and located these insertions on the S. paratyphi A chromosome through the XbaI and AvrII sites in Tn10 and through the increased size of the SpeI fragment bearing a Tn10. Compared with the maps of other Salmonella species, the S. paratyphi A genomic map showed two major differences: (i) an insertion of about 100 kb of DNA between rrnH/G and proB and (ii) an inversion of half the genome between rrnH and rrnG, postulated to be due to homologous recombination between the rrn genes. We propose that during the evolution of S. paratyphi A, the first rearrangement event was the 100-kb insertion, which disrupted the chromosomal balance between oriC and the termination of replication, forcing the rrnH/G inversion to restore the balance. The insertion and the inversion are both present in all 10 independent wild-type S. paratyphi A strains tested.     

Delayed hypersensitivity in murine salmonellosis: specificity of footpad reaction in mice infected with rough mutants of Salmonella typhimurium

Delayed type (footpad) hypersensitivity (DTH) in BALB/c mice immunized with rough mutant strains of Salmonella typhimurium LT2 was examined. Injection of live organisms of an Rb mutant TV148 strain induced DTH in mice, while injection of the heat-killed organisms did not. The mice immunized with live organisms of the Ra, Rb, Rc, Rd, and Re mutant strains showed positive footpad reactions to the heat-killed cell antigen of LT2 (wild type) strain. The mice immunized with the Rb mutant strain also showed positive footpad swellings in response to heat-killed cell antigens of S. paratyphi A, S. paratyphi B, S. typhi, S. enteritidis, and S. cholerae-suis. Furthermore, positive reactions to antigens of Escherichia coli and Shigella flexneri were seen in the TV148-immunized mice, but the mice did not respond to heat-killed organisms of Pseudomonas aeruginosa or Staphylococcus aureus. The cross-reactive footpad reaction to E. coli could be transferred adoptively with T cells prepared from the spleens of TV148-immunized mice into syngeneic recipients. These results suggest that the cross-reactive DTH antigen(s) is widely distributed among related organisms such as Shigella and Escherichia.     

Genetics of Sensitivity of Salmonella Species to Colicin M and Bacteriophages T5, T1, and ES18

Nearly all of 62 strains of Salmonella paratyphi B were sensitive to colicin M and phage T5 but resistant to phages T1 and ES18 and to colicin B. All tested S. typhimurium strains were resistant to colicin M and phage T5, and many were sensitive to phage ES18. A rough S. typhimurium LT2 strain given the tonA region of Escherichia coli or S. paratyphi B became sensitive to colicin M and phage T5. We infer that the tonA allele of S. paratyphi B, like that of E. coli, determines an outer membrane protein that adsorbs T5 and colicin M but not phage ES18, whereas the S. typhimurium allele determines a protein able to adsorb only ES18. The partial T1 sensitivity of a rough LT2 strain with a tonA allele from E. coli or S. paratyphi B and also the tonB(+) phentotype of an E. coli B trp-tonB Delta mutant carrying an F' trp of LT2 origin showed that S. typhimurium LT2 has a tonB allele like that of E. coli with respect to determination of sensitivity to colicins and phage T1. Rough S. paratyphi B, although T5 sensitive, remained resistant to T1 even when given F' tonB(+) of E. coli origin. Classes of Salmonella mutants selected as resistant to colicin M included: T5-resistant mutants, probably tonA(-); mutants unchanged except for M resistance, perhaps tolerant; and Exb(+) mutants, producing a colicin inhibitor (presumably enterochelin). Some Exb(+) mutants were resistant to a bacteriocin inactive on E. coli but active on all tested S. paratyphi B and S. typhimurium strains (and on nearly all other tested Salmonella). A survey showed sensitivity to colicin M in several other species of Salmonella.     

Genetic diversity of human isolates of Salmonella enterica serovar Enteritidis in Malaysia

AIMS: The study was undertaken to determine clonal relationship and genetic diversity of the human strains of Salmonella enterica serovar Enteritidis isolated from 1995 to 2002 from different parts of Malaysia. METHODS AND RESULTS: Antimicrobial susceptibility test, plasmid profiling and pulsed-field gel electrophoresis were applied to analyse 65 human isolates of S. Enteritidis obtained over an eight year period from different parts of Malaysia. Four nonhuman isolates were included for comparison. A total of 14 distinct XbaI-pulsed-field profiles (PFPs) were observed, although a single PFP X1 was predominant and this particular clone was found to be endemic in Malaysia. The incidence of drug resistant S. Enteritidis remained relatively low with only 37% of the strains analysed being resistant to one or more antimicrobial agents. All except one resistant strain carried at least one plasmid ranging in size from 3.7 to 62 MDa giving nine plasmid profiles. The three isolates from raw milk and one from well-water had similar PFPs to that of the human isolates. CONCLUSIONS: Salmonella Enteritidis strains were more diverse than was previously thought. Fourteen subtypes were noted although one predominant clone persisted in Malaysia. The combination of pulsed-field gel electrophoresis, plasmid profiling and antibiograms provided additional discrimination to the highly clonal strains of S. Enteritidis. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report to assess the genotypes of the predominant clinical S. Enteritidis in different parts of the country. As S. Enteritidis is highly endemic in Malaysia, the data generated would be useful for tracing the source during outbreaks of gastroenteritis in the study area.     

Salmonella interactions with host cells: in vitro to in vivo

Salmonellosis (diseases caused by Salmonella species) have several clinical manifestations, ranging from gastroenteritis (food poisoning) to typhoid (enteric) fever and bacteraemia. Salmonella species (especially Salmonella typhimurium) also represent organisms that can be readily used to investigate the complex interplay that occurs between a pathogen and its host, both in vitro and in vivo. The ease with which S. typhimurium can be cultivated and genetically manipulated, in combination with the availability of tissue culture models and animal models, has made S. typhimurium a desirable organism for such studies. In this review, we focus on Salmonella interactions with its host cells, both in tissue culture (in vitro) and in relevant animal models (in vivo), and compare results obtained using these different models. The recent advent of sophisticated imaging and molecular genetic tools has facilitated studying the events that occur in disease, thereby confirming tissue culture results, yet identifying new questions that need to be addressed in relevant disease settings.     

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.     

Expression of a new porin 'OmpE' by strains of Salmonella enteritidis

Abstract Strains of Salmonella enteritidis expressed a novel porin with a subunit size of 35.5 kDa as shown by SDS-PAGE. This protein was expressed as a major outer membrane protein (MOMP) when grown on nutrient agar, McConkey agar or blood agar, or in Tris-succinate medium; but was only produced in trace amounts when strains were grown in nutrient broth. This OMP was produced by all strains of S. enteritidis examined, regardless of phage type, and expression was not related to the possession of a 38-MDa mouse-virulence plasmid or the ability of strains to make long-chain lipopolysaccharide. This new porin has been tentatively called OmpE.     

Comparative Survival of Indicator Bacteria and Enteric Pathogens in Well Water

The comparative survival of various fecal indicator bacteria and enteric pathogens was studied in a stable well water supply by using membrane chambers. There was more variation in the 29 coliform cultures and they died more rapidly, as a group, than the 20 enterococcus cultures that were examined. The comparative survival of the organisms tested follows: Aeromonas sp. > the shigellae (Shigella flexneri, S. sonnei, and S. dysenteriae) > fecal streptococci > coliforms = some salmonellae (Salmonella enteritidis ser. paratyphi A and D, S. enteritidis ser. typhimurium) > Streptococcus equinus > Vibrio cholerae > Salmonella typhi > Streptococcus bovis > Salmonella enteritidis ser. paratyphi B. S. bovis had a more rapid die-off than did S. equinus, but both had significantly shorter half-lives than the other streptococci. The natural populations of indicator bacteria from human and elk fecal material declined similarly to the pure cultures tested, whereas the die-off of fecal streptococci exceeded the coliforms from bovine fecal material.     

Taxonomy of Marine Bacteria: Beneckea parahaemolytica and Beneckea alginolytica

A collection of 169 strains, including 91 obtained from cases of gastroenteritis and 41 from localized tissue infections and infections of the eye and ear, was submitted to an extensive nutritional, physiological, and morphological characterization. The nutritional and physiological data obtained from these strains, as well as data for strains of other species of the genus Beneckea, were submitted to a numerical analysis which grouped the strains into clusters on the basis of phenotypic similarity. Strains from cases of gastroenteritis formed a group of three clusters which linked at a similarity value of 68%. These three clusters could not, however, be separated from each other by universally positive or negative traits, and on the basis of their overall phenotypic similarity were assigned to a single species, B. parahaemolytica. The majority of the strains from human, nonenteric sources segregated into two distinct clusters, one designated B. alginolytica and the other unassigned with respect to species (group C-2). B. parahaemolytica, B. alginolytica, and group C-2 could be readily distinguished from one another as well as from the remaining species of the genus Beneckea by multiple, unrelated, phenotypic traits. Activities of selected enzymes of glucose and gluconate catabolism in cell-free extracts of B. parahaemolytica, B. alginolytica, and group C-2 suggested that these organisms utilized glucose primarily via the Embden-Meyerhof pathway and gluconate primarily via the Entner-Doudoroff pathway. Similar results were observed in the other members of the genus Beneckea.     

An investigation into the pathogenic properties of Escherichia coli strains BLR, BL21, DH5alpha and EQ1

AIMS: To examine Escherichia coli strains EQ1, DH5alpha, BLR and BL21 for known pathogenic mechanisms. METHODS AND RESULTS: Using specific DNA probes, the strains were shown not to carry the genes encoding invasion, various adhesion phenotypes or expression of a range of enterotoxins. The strains were unable to express long-chain lipopolysaccharide and were susceptible to the effects of serum complement. Using a BALB/c mouse model, the strains were shown to be unable to survive in selected tissues or to persist in the mouse gut. Using a chick model, strains EQ1, BLR and BL21 invaded livers but not spleens; only strain EQ1 persisted in the chick gut. In Merino sheep, only strain EQ1 was detected 6 d post-infection. CONCLUSIONS: Escherichia coli strains EQ1, DH5alpha, BLR and BL21 did not carry the well-recognized pathogenic mechanisms required by strains of E. coli causing the majority of enteric infections. SIGNIFICANCE AND IMPACT OF THE STUDY: Escherichia coli strains EQ1, DH5alpha, BLR and BL21 were considered to be non-pathogenic and unlikely to survive in host tissues and cause disease.     

Occurrence of Salmonella spp and Cryptosporidium spp in a French coastal watershed: relationship with fecal indicators

Cryptosporidium and Salmonella are pathogenic microorganisms that can cause severe gastrointestinal illness in humans. Because these organisms are potentially transmitted through natural waters, this study was carried out to estimate the concentrations of both pathogens in a French coastal watershed and to determine the relationships with fecal indicators. Water samples from nine wastewater treatment plants and eight rivers were analyzed. Although both pathogens and indicators are released from sewage effluents, no clear correlation was found between the two enteric pathogens nor between a given pathogen and fecal indicators. These results suggest that fecal indicators do not adequately indicate the presence of Cryptosporidium and Salmonella in natural waters and that pathogens and indicators may have different behaviors in the aquatic environment.     

Role of Genomic Rearrangements in Producing New Ribotypes of Salmonella typhi

Salmonella typhi is the only species of Salmonella which grows exclusively in humans, in whom it causes enteric typhoid fever. Strains of S. typhi show very little variation in electrophoretic types, restriction fragment length polymorphisms, cell envelope proteins, and intervening sequences, but the same strains are very heterogeneous for ribotypes which are detected with the restriction endonuclease PstI. In addition, the genome of S. typhi has been proven to undergo genomic rearrangement due to homologous recombination between the seven copies of rrn genes. The relationship between ribotype heterogeneity and genomic rearrangement was investigated. Strains of S. typhi which belong to 23 different genome types were analyzed by ribotyping. A limited number of ribotypes were found within the same genome type group; e. g., most strains of genome type 3 belonged to only two different ribotypes, which result from recombination between rrnH and rrnG operons. Different genome type groups normally have different ribotypes. The size and identity of the PstI fragment containing each of the seven different rrn operons from S. typhi Ty2 were determined, and from these data, one can infer how genomic rearrangement forms new ribotypes. It is postulated that genomic rearrangement, rather than mutation, is largely responsible for producing the ribotype heterogeneity in S. typhi.     

A study of enteropathogenic organisms isolated in the public health laboratory, Lusaka.

A total of 328 specimens of stools were examined in the Public Health Laboratory during January and February 1973. Enteropathogens were isolated from 117 of these specimens. Besides these, 12 strains of Salmonellae were isolated from blood and 8 from urine. An occasional Salmonella was isolated from the pleural fluid (S. paratyphi A) pus from the knee (S. enteritidis) and from the C.S.F. of an infant (S. paratyphi C.). Salmonella typhi and Salmonella paratyphi A are the predominant Salmonella species. No Salmonella paratyphi B has been isolated. Shigella, was isolated with slightly less frequency than Salmonella, and Shigella flexneriis was the predominant species. E. coli 0112/K66 is the most common enteropathogenic E. coli. The majority of the Shigella and Salmonella species are sensitive to the common antibiotics used. The E. coli organisms show multiple resistance to a number of antibiotics.     

Antibiotic resistance and genotyping of clinical group B Salmonella isolated in Accra,Ghana

AIMS: The purpose of this study was to investigate the antibiotic resistance and clonal lineage of serogroup B Salmonella isolated from patients suspected of suffering from enteric fever in Accra, Ghana. METHODS AND RESULTS: Serogroup B Salmonella were isolated from blood (n=28), cerebral spinal fluid (CSF) (n=1), or urine (n=2), and identified based on standard biochemical testing and agglutinating antisera. Isolates were examined for their susceptibility to ampicillin, chloramphenicol, tetracycline and trimethoprim-sulfamethoxazole. Most of the isolates could be classified as multiple-drug resistant. Furthermore, the genetic location of resistance genes was shown to be on conjugative plasmids. Genetic fingerprinting by plasmid profiling, enterobacterial repetitive intergenic consensus (ERIC)-PCR, and repetitive element (REP)-PCR were performed to determine the diversity among the isolates. Plasmid profiling discriminated five unique groupings, while ERIC-PCR and REP-PCR resulted in two and three groupings, respectively. CONCLUSIONS: A high rate of antibiotic resistance was associated with the Salmonella isolates and the genes responsible for the resistance are located on conjugative plasmids. Also, there appears to be minimal diversity associated with the isolates. SIGNIFICANCE AND IMPACT OF THE STUDY: As a result of the increasing antibiotic resistance among bacteria of all genera, surveys to monitor microbial populations are critical to determine the extent of the problem. The inability to treat many infectious diseases with current antibiotic regimens should prompt the medical community to be more prudent with its antibiotic use.     

Linkage of avian and reproductive tract tropism with sequence divergence adjacent to the 5S ribosomal subunit rrfH of Salmonella enterica

The 183 bp between the end of the 23S rrlH rRNA gene and the start of the 5S rrfH rRNA gene (ISR-1) and the 197 bp between the end of the rrfH rRNA gene and the start of the transfer RNA aspU (ISR-2) of Salmonella enterica ssp. enterica serotypes Enteritidis, Typhimurium, Pullorum, Heidelberg, Gallinarum, Typhi and Choleraesuis were compared. ISR-1s of D1 serotypes (Pullorum, Gallinarum and Enteritidis), B serotypes (Typhimurium and Heidelberg) and the C2 serotype Newport and the enteric fever pathogens serotype A Paratyphi and serotype D1 Typhi formed three clades, respectively. ISR-2 further differentiated the avian-adapted serotype Gallinarum from avian-adapted Pullorum and Salmonella bongori from S. enterica. The results suggest that serotypes Heidelberg and Choleraesuis share some evolutionary trends with egg-contaminating serotypes. In addition, ISR-1 and ISR-2 sequences that confirm serotype appear to be linked to clinically relevant host associations of the Salmonellae.     

伤寒沙门菌动物模型研究进展

目前伤寒沙门菌引起的人类伤寒仍是一种严重危害人类健康的疾病,且近年来多重耐药伤寒沙门菌株频频出现,使伤寒的治疗更加棘手.由于该菌具有严格的宿主特异性,又缺乏理想的动物模型,其致病机制的研究、疫苗及药物的研发受制约.新近研究发现,免疫系统人源化小鼠模型和诱导型一氧化氮合酶基因敲除小鼠模型可用于伤寒沙门菌的体内实验.本文就其应用现状及缺憾作一综述.     

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.