Surveillance for typhoid fever in Matsuyama city during 1974-1981 and detection of Salmonella typhi in sewage and river waters

Eighty-two cases of typhoid fever were found in Matsuyama city in the period from 1974 to 1981. Seventy-six cases were found to be infected with Salmonella typhi other three with Salmonella paratyphi A, and the remaining three were diagnosed only clinically. The strains of S. typhi isolated from these patients showed such a variety of Vi-phage types as D1, D2, E1, M1, 53 and degraded Vi-positive strain (DVS). The concurrent survey of the city sewage and river waters for typhoid bacilli was conducted with total 578 samples taken therefrom. S. typhi was isolated from 120 of those samples. The Vi-phage types of the isolates were closely related with those of the isolates from the patients. The periodical examinations of the city sewage and the draining river may serve as a useful means for the controlling typhoid fever epidemics.     

Pathogenetic and immunological characteristics of different forms of the Salmonella typhi carrier state

Infectious granulomas with macrophages containing Salmonella typhi have been detected in the immune organs of the intestine of typhoid patients by means of morphological investigation techniques, immunofluorescent and electron microscopy. This suggests that typhoid granulomas form the basis of S. typhi primary carriership complicated by the relapses of this infection in cases of weakened cell-mediated immunity, which is proved by a decrease in the level of T-lymphocytes and by increased leukocyte migration index in relapses of typhoid fever and in S. typhi primary carriership. At the same time, the formation of S. typhi secondary carriership occurs in the process of the colonization of the altered organs and tissues of the body by S. typhi. This secondary carriership differs from the primary one by a number of pathogenetic signs. The detailed characterization of these two forms of S. typhi carriership is presented.     

Adenylate kinase isoenzymes in Aspergillus nidulans

Multiple HindIII-restriction fragments of Salmonella typhimurium and Salmonella typhi chromosomal DNA exhibited homology with the heat-labile enterotoxin (LT1) gene of Escherichia coli as determined by Southern blot analysis. A 9.4 kb HindIII restriction fragment identified in S. typhimurium and S. typhi chromosomal DNA reacted with both eltA and eltB gene probes. However, the homology of the 9.4 kb DNA fragment from these Salmonella species was greater with eltB than eltA. In addition, a synthetic oligonucleotide probe, made to a portion of the putative GM1-ganglioside binding region of cholera toxin (CT) and LT1, hybridized with the 9.4 kb DNA fragment of S. typhimurium but not with the 9.4 kb fragment found in S. typhi isolates. The hybridization of multiple restriction fragments of Salmonella DNA with eltA and eltB gene sequences further suggests duplication of the stx operon on the chromosome of these bacteria.     

Demonstration of an antigenic protein specific for Salmonella typhi

Current studies were undertaken to determine the presence of a specific antigenic protein on the outer membrane of Salmonella typhi. Immunoblot analysis using sera from patients with fevers revealed that the 50 kD band was specifically recognized only by typhoid sera. The 50 kD band located on the outer membrane is protein by nature and is not a Vi (capsular), dH (flagellar), or O9 (somatic) antigen of S. typhi. These results indicate the usefulness of the specific antigen in the development of a serodiagnostic test for typhoid fever since antibodies of both the IgM and IgG class responses were obtained.     

vi—PHA试剂的研制及其在检测伤寒带者中的应用

Purified S. typhi Vi antigen is sensitized with equal volume of tannic acid treated formalational sheep erythrocytes (SRBC) at a final concentration of 1 microgram/ml. The Vi-passive hemagglutination assay (Vi-PHA) diagnostic reagent is developed to detect Vi antibodies to S. typhi for the detection of chronic carriers after typhoid fever and the screening S. typhi healthy carriers from food-handlers, which is characterized with high sensitivity, strong specificity and good stability. This Vi-PHA reagent is able to detect 1.16 micrograms/ml of Vi antibodies and doesn't make any cross reaction with healthy sera. For the sera of other diseases, the cross rate is only 0.84%. Using this reagent, 19 positive sera (6.93%) are detected from 274 convalescent sera from typhoid fever, 14 convalescents of which are stool-culture S. typhi positive, that persists a positive rate of 73.68%; 3 positive sera are detected from 106 foodhandlers, one of which is stool-culture S. typhi positive. Therefore, the reagent is simple, convenient, rapid and easy to be applicated in basic unit.     

Development of specific cellular immunoreactivity in typhoid fever.

Development of cellular immunoreactivity to Salmonella typhi and Salmonella paratyphi-A was studied by the leukocyte migration inhibition test in 9 patients with typhoid fever and in 2 patients with paratyphoid fever. Cellular reactivity could be demonstrated from the first days of the disease in all the subjects. The most pronounced migration inhibition was observed during the febrile period. It is suggested that specific cellular reactivity may play a pathogenetic role in typhoid fever.     

Transient inhibition of glucose utilization by erythrocytes during the acute stage of typhoid fever

The exact reason for hemolysis of glucose-6-phosphate dehydrogenase-deficient (G6PD) erythrocytes in patients with typhoid fever is unknown. Therefore, glucose utilization by normal and G6PD-deficient erythrocytes was measured during incubation with plasma of healthy controls as well as from patients in acute or recovery stages of typhoid fever. Glucose utilization in normal and G6PD-deficient erythrocytes significantly decreased compared to the controls when incubated with plasma of patients with acute typhoid fever, which normalized to the baseline after recovery from typhoid fever, suggesting an acquired alteration in G6PD enzyme properties by Salmonella typhi or its endotoxins.     

Leukocyte migration inhibition by a specific antigen in human typhoid fever.

Cellular reactivity to heat-killed Salmonella typhi antigen was investigated by the leukocyte migration inhibition (LMI) method in 33 S. typhi infected patients and in 32 control persons. In the typhoid group a statistically significant LMI was observed as compared to the members of the control group. A correlation was found between the level of the cellular sensitivity and the time elapsed between onset of the disease and performance of the test. Previous typhoid vaccination had no influence on the LMI. No correlation was found between the agglutinin titres and the sensitivity demonstrated by the LMI test. The value of the method in studies of cellular immunity in typhoid fever is discussed.     

Mecillinam: a new antibiotic for enteric fever.

Mecillinam is a new antibiotic related to the penicillins but more active than ampicillin against salmonellae, including Salmonella typhi. Mecillinam must be administered parenterally, but the ester, pivmecillinam, is absorbed from the gut. Eight patients suffering from typhoid fever and one suffering from paratyphoid fever were treated with the antibiotic, and seven responded satisfactorily. One patient could not tolerate pivmecillinam because of vomiting but there were no other adverse reactions. Serum and bile levels of mecillinam were many times the minimum inhibitory concentrations for most salmonellae. The antibiotic is a promising addition to the agents available for treating typhoid.     

Determination of O and Vi antigens in typhoid fever in the slide coagglutination reaction

Investigations with a view to the development and trial of a slide coagglutination test system for the detection of specific Salmonella typhi antigens have been made. As a result, diagnostic agents with sensitivity to group D Salmonella lipopolysaccharides and Vi-antigen, equal to 1 X 10(-5) to 1 X 10(-6) g/l, have been obtained. Specimens of saliva, urine and fecal filtrates from 61 adult patients with bacteriologically confirmed typhoid fever and 54 practically healthy persons have been studied. The coagglutination test has been positive with specimens from 90 +/- 4% of typhoid fever patients and, within the first 5 days of the disease, with those from 85 +/- 7% of such patients. The slide coagglutination test with saliva specimens has been found to be more informative than that with urine specimens. The data obtained in these investigations indicate that the slide coagglutination test is highly sensitive and specific, which offers good prospects for its use as a simple, economic and demonstrative method for the early tentative diagnosis of typhoid fever.     

Reaction and response of newborn guinea pigs to experimental Salmonella typhi infection

Newborn guinea pigs, orally infected with Salmonella typhi were examined at various intervals of time in order to determine bacterial distribution in tissues and to establish possible correlation with the clinical aspects manifested. Histopathological examination evidenced typical lesions in jejunum, ileum, caecum and especially in regional lymphatic tissues. Spleen, liver and mesenteric lymph nodes presented granulomatous lesions similar to those observed in in human typhoid fever. After oral administration, the animals reacted with anorexia, febrile reactions, bacteremia, diarrhoea, positive stool cultures, dehydration, lethargy and antibodies too were produced. Our results indicate that typhoid infection may be induced in newborn guinea pigs; the model may be used for an assessment of attenuated live typhoid vaccine control.     

Comparative trial of Co-trimoxazole and Chloramphenicol in Typhoid Fever

A comparative trial of co-trimoxazole and chloramphenicol was conducted in two groups of 50 patients each to try to resolve conflicting opinions on the relative merits of the two drugs in the treatment of typhoid fever. We conclude that in our part of India co-trimoxazole is superior to chloramphenicol and that differences in our findings to those of others may perhaps be accounted for by differences in strains of Salmonella typhi, ethnic differences, and possibly differences in herd immunity to typhoid.     

Detection of Salmonella typhi by polymerase chain reaction

A rapid and sensitive method for detection of Salmonella typhi would help in preventing the spread of outbreaks and in clinical diagnosis. In order to develop unique PCR primers to detect Salm. typhi , ribosomal RNA genes from Salm. typhi (Rawlings) were cloned in pUC18. The resulting clone was confirmed by sequencing. The cloned DNA fragment contained the 5S, part of the 23S rRNA genes and the 5S-23S spacer region (EMBL/GenBank accession No. U04734).
It was expected that the 5S-23S spacer region is divergent unlike the highly conserved 23S+5S genes. This was confirmed by comparison with the rRNA gene sequences in the EMBL/GenBank database. A pair of PCR primers specific for Salm. typhi was obtained, based on this spacer region sequence. The specificity of this pair of primers was tested with 54 Salm. typhi strains (of 27 different phage types). All these Salm. typhi strains showed the positive 300 bp PCR product with this pair of primers. Six other Salmonella species as well as six other non- Salmonella bacteria were tested and none showed the 300 bp PCR product. The sensitivity of the detection level was 0·1 pg of pure Salm. typhi genomic DNA, or approximately 40 Salm. typhi cells in a spiked food sample. This pair of primers therefore has the potential for development into a diagnostic tool for the rapid diagnosis of typhoid fever.     

Antibiotic sensitivity of S. typhi cultures that have reverted from L forms isolated from the blood of patients]

L-forms of bacteria were isolated in 18 out of 300 fever patients with diagnoses of typhoid-paratyphoid fever, grippe, virus respiration disease and others in the Diagnostic Department of an Infection Hospital during bacteriological tests of the blood. Among the cultures tested 13 were instable and reversed to the bacterial form. The type identification showed that only 9 revertants possessed properties characteristic of the typhoid fever microbes and belonged to S. typhi. Sensitivity of the typhoid fever revertants to levomycetin, sintomycin, streptomycin, pencillin and tetracycline was studied. The studies showed that the typhoid fever revertants from the L-forms isolated from the patients were sufficiently sensitive to levomycetin, sintomycin, penicillin and tetracycline. The minimum bactericidal concentrations of the above antibiotics ranged within 12.5--100 gamma/ml.     

Salmonella Typhi sense host neuroendocrine stress hormones and release the toxin haemolysin E

Salmonella enterica serovar Typhi (S. typhi) causes typhoid fever. We show that exposure of S. typhi to neuroendocrine stress hormones results in haemolysis, which is associated with the release of haemolysin E in membrane vesicles. This effect is attributed to increased expression of the small RNA micA and RNA chaperone Hfq, with concomitant downregulation of outer membrane protein A. Deletion of micA or the two-component signal-transduction system, CpxAR, abolishes the phenotype. The hormone response is inhibited by the β-blocker propranolol. We provide mechanistic insights into the basis of neuroendocrine hormone-mediated haemolysis by S. typhi, increasing our understanding of inter-kingdom signalling.     

Efficacy of various antimicrobial agents in the treatment of epidemic typhoid fever]

During superepidemic of a typhoid fever in Tadjikistan the efficiency of application in clinics and of 14 antimicrobial agents representing almost all basic chemical classes was investigated. Remarkable variation of frequency and type of S. typhi resistance to these preparations up to epidemic and especially in its process was demonstrated. The absence of absolute (100%) efficacy of the investigated agents in vivo and in vitro was shown. The reasons of low efficacy of etiotropic treatment of the patients with typhoid fever are analysed.     

New knowledge on pathogenesis of bacterial enteric infections as applied to vaccine development.

This review attempts to synthesize the new knowledge of pathogenesis of bacterial enteric infections and relate this information to vaccine development. Discussion focuses on human infections and to those in which significant strides have been made. As a general theme in the pathogenesis of bacterial enteric infections, pathogens can be characterized into 5 groups on the basis of their degree of ultimate invasiveness after ingestion by a susceptible hose: mucosal adherence and enterotoxin production; mucosal adherence and brush border dissolution -- enteropathogenic E. coli (EPEC) of "classical" serotypes; mucosal invasion and intraepithelial cell proliferation; mucosal translocation followed by bacterial proliferation in the lamina propria and mesenteric lymph nodes; and mucosal translocation followed by generalized infection. The review covers cholera (motility and chemotaxis, mucosal adhesion, flagellar sheath protein, hemagglutinins, outer membrane proteins, enterotoxin production, quality and duration of infection derived immunity, immune response in humans, LPS, flagellar sheath protein, cholera lectin, other cholera hemagglutinins, outer membrane protein, previous cholera vaccines, killer whole cell vaccines, toxoids, combination vaccines, attenuated versus cholerae vaccines): enterotoxigenic Escherichia coli (ETEC) (entertoxins, O:H serotypes and enterotoxin phenotypes, colonization factors, immune response in humans, vaccines against ETEC, and toxiods); EPEC (vaccines against EPEC); Shigella (smooth LPS O antigen, epithelial cell invasiveness, Shigella toxin, and Shigella vaccines); and typhoid fever (caccines against typhoid fever). The major attraction of a nonliving oral cholera vaccine is its safety. A review of available information leads to the conclusion that an oral vaccine consisting of a combination of antigens, intending to stimulate both antibacterial and antitoxic immunity, would be most likely to succeed. Current approaches to immunoprophylaxis of ETEC infection involve vaccines that stimulate antitoxic or antiadhesion immunity or both by means of killed antigens or attenuated strains. It is likely that the most effective vaccines will contain appropriate antigens intended to simultaneously stimulate both antibacterial and antitoxic immunity, thereby leading to a synergistic protective effect. Now that the speical enteroadhesive properties of EPEC have been characterized and shown to be associated with a plasmid, it should be possible to identify the phenotypic gene products responsible for this phenomenon. It is likely that fimbriae or outer membrane proteins will prove to be the organelle of adhesion. When such information becomes available, it should be possible to prepare oral vaccines consisting of the purified antigen. Efficacy has been shown for attenuated Shigella strains utilized as oral vaccines. The major thrust in the development of new immunization agensts against typhoid fever is to identify immunizing agents at least equal in efficacy to the parenteral acetone killed vaccine but which cause no adverse reactions.     

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.     

Immunofluorescent Identification of Salmonella typhi During a Typhoid Outbreak

Immunofluorescence and conventional bacteriological methods were compared for their ability to detect Salmonella typhi in 134 fecal specimens from 105 individuals associated with an outbreak of typhoid fever. Smears prepared from untreated fecal material (direct method) and after a preliminary incubation in selenite F broth (delayed method) were tested with an anti-Vi serum conjugated with fluorescein isothiocyanate. The delayed method was more sensitive than the direct method in detecting S. typhi. The delayed method was positive in 40 of 41 patients positive by culture methods, but gave positive or questionable reactions in 11 presumably uninfected individuals. The fluorescent-antibody test employing a Vi conjugate is a satisfactory screening procedure for detecting S. typhi, but all positives must be confirmed bacteriologically.     

Molecular characterization of antibiotic resistance in clinical Salmonella typhi isolated in Ghana

Fifty-eight clinical Salmonella typhi strains isolated from patients suspected of suffering from typhoid fever were obtained at the Korle-Bu Teaching Hospital and the Noguchi Memorial Institute for Medical Research, both located in Ghana, Africa. Each isolate was examined for susceptibility to ampicillin, chloramphenicol, streptomycin, tetracycline, and trimethoprim/sulfamethoxazole by the disk diffusion assay. Five of the isolates were resistant to all five antibiotics while 10 isolates were resistant to ampicillin, chloramphenicol, and trimethoprim/sulfamethoxazole, which are considered 'first line' antibiotics in the treatment of typhoid fever. Thirty-four isolates were resistant to at least one of the antibiotics tested and 62% of these isolates possessed conjugable plasmids belonging to incompatibility group IncHI. Ninety percent of the conjugable plasmids conferred a multiple drug-resistant phenotype on the strains harboring them. Additionally, 14 strains contained plasmids that were transformable and six of them encoded multiple drug resistance. Our findings indicate that multiple drug resistance to the 'first line' antibiotics in S. typhi may be more prevalent in Africa than previously thought.