Prevalence of multi-drug resistant Salmonella typhi among clinically diagnosed typhoid fever patients in Lagos, Nigeria

A total of 635 clinically diagnosed typhoid fever patients were bled from three different health institutions in the metropolis of Lagos, Nigeria over a period of 15 months, May 1997 to July 1998. Out of the total blood cultured, 101 (15.9%) isolates of Salmonella species were isolated of which 68 (67.3%) were S. typhi, 17 (16.8%) and 16 (15.8%) were S. paratyphi A. and S. arizonae respectively. The overall isolation rate of S. typhi among patients is 10.7%, with most isolates 45.9% found among the severely-ill young adults, age group 16-30 years. All isolates were subjected to anti-microbial susceptibility testing using 12 different antibiotics: chloramphenicol, ampicillin, cotrimoxazole, gentamicin, colistin sulfate, nalidixic acid, nitrofurantoin, cefotaxime, tetracycline, streptomycin, ofloxacin and ciprofloxacin. All the S. typhi and S. paratyphi A isolates showed resistance to two or more of the 10 of 12 antibiotics tested particularly the 3-first-line antibiotics commonly used (chloramphenicol, ampicillin and cotrimoxazole) in the treatment of typhoid fever in Nigeria. No isolate showed resistance to ofloxacin and ciprofloxacin, however, nalidixic acid and gentamicin showed a moderate and appreciable inhibition to most of our isolates.     

Isolation of a highly purified capsular polysaccharide from Salmonella enterica serovar Typhi (Salmonella typhi)--Vi-antigen and its use in serological diagnosis of typhoid fever

For use in differential diagnostics of typhoid fever, samples of the capsular polysaccharide from Salmonella enterica serovar Typhi (usually named Vi-antigen) were isolated and characterized by physicochemical and serological methods. It was shown that only the sample of Vi-antigen with the minimal (0.57%) admixture of the corresponding lipopolysaccharide (LPS) from S. typhi retained a high serological activity in the tests with monoreceptor anti-Vi sera. However, it exhibited a substantially weaker reaction with sera from normal donors and patients with acute nontyphoid salmonelloses, than Vi-antigen preparations with a higher (0.8-1.2%) LPS content. The chromatographically pure Vi-antigen was purified by triple reprecipitation with hexadecyltrimethylammonium bromide. The content of the LPS admixture in the resulting Vi-antigen samples was quantitatively determined by GC. A high purification level of the Vi-antigen from the LPS admixture allows us to hope that this preparation could serve as a basic component of the test system for the diagnostics of typhoid fever. The English version of the paper.     

The function of Salmonella typhi at different stages in the pathogenesis of typhoid infection

The complex study of the adhesive, colicinogenic and antigenic properties of S. typhi of different origin has revealed that adhesive properties can be observed more frequently in the strains isolated from the blood and bile and are completely absent in the strains isolated from feces. S. typhi strains of various origin do not essentially differ in their sensitivity to colicins and in the capacity for their production. Among the strains isolated from feces and bile, agents in the W-form occur more frequently than among the strains isolated from the blood. Escherichia coli, isolated from typhoid patients and carriers at the moment of the persistence of S. typhi in the body, are characterized by faintly pronounced antagonistic properties, enhanced sensitivity to colicins and rather pronounced hemagglutinating activity.     

Characteristics of lipopolysaccharides ofSalmonella typhi isolated from carriers and patients suffering from typhoid fever

Lipopolysaccharides (LPS) ofSalmonella typhi strains, isolated from carriers and patients suffering from typhoid fever, were characterised according to their biochemical properties, morphological structure and degree of aggregation of complexes. All preparations of LPS, regardless of their origin, were morphologically heterogeneous. Free electrophoresis and immunoelectrophoresis demonstrated that LPS preparations were composed of components possessing different mobilities in electric fields. LPS of bacterial strains isolated from both carriers and patients, split upon reaction in immunoelectrophoresis with specific antiserum 73, rabbit antiserum toSalmonella typhi Vi Bhatnagar and 0–901 split into anodic and cathodio fractions. The anodic fraction reacted similarly as Vi antigen. LPS fromSalmonella typhi Ty-2 yielded only the cathodic fraction, typical for O antigen. LPS from strains whioh were passaged twice in nutritional medium possessed identical properties as LPS from fresh cultures ofSalmonella typhi. Electron microscopy revealed that LPS appears as long bands, rods, ellipsoid forms and amorphous material. Contrary to amorphous material, the bands, rods and ellipsoid forms possessed three-layer structure.     

Detection of microbial variants of Salmonella typhi in the bone marrow of typhoid patients and carriers

The immunofluorescence test with the use of antisera to S. typhi and its L-forms permits the detection of the infective agent in bone marrow smears. This diagnostic method is particularly important in cases of carrier state in the latent phase and in differential diagnosis. As revealed in this study, the microbial variants of S. typhi, reacting with antiserum to its L-forms, are present in the bone marrow of carriers. They are localized, as a rule, on the membranes of lymphoid and erythroid cells, which probably leads to the formation of rosettes.     

Occurrence of Salmonella typhi and Salmonella paratyphi in Jordan

In order to justify the surveillance control system and hygiene policy in Jordan, this study evaluated the occurrence of diarrhoea during the period 1988-2000, focusing on cases caused by Salmonella typhi and Salmonella paratyphi. From January 1988 to December 2000, the number of notified diarrhoeal cases by the Ministry of Health in Jordan was 1,399,563 million. Other groups of patients confined to the Governorate of Amman was diagnosed at Al-Battikhi Medical Laboratories. One-way ANOVA and Least Significant Difference (LSD) were carried out for statistical analysis. The number of reported diarrhea cases was 1,399,563, 53.0% were males, and 47.0% were females, among them, 80.3% were < 20 years and 19.7%, were > 20 years. Out of 245,255 patients tested for S. typhi and S. pararyphi, positive stool culture were 1992 (0.6%). Out of these, 960 (48.2%) were males and 1,032 (51.8%) were females (P = 0.028). The highest incidence rate (10.8) was observed in the year 1993, while the lowest incidence rate (0.9) was found in year 2000. A significant difference (P < 0.001) was found between the number of S. typhi and S. Paratyphi cases and year. The seasonal variation was also found to be significant (P < 0.0001), with the summer period showing the highest incident rate. A significant difference (P < 0.001) was observed between number of typhoid and paratyphoid cases and districts. A significance difference between number of typhoid and paratyphoid cases with age and sex. The group most affected was school age and adolescence. The demographic situation plays an important role in reporting typhoid and paratyphoid cases, where there might be an urgent indication for a better surveillance control system on water resources and disposal systems. S. typhi and S. paratyphi antibiotics resistance pattern showed they were resistant to tetracycline (56.0%, 58.0%), ampicillin (45.0%, 48.0%), trimethoprim (43.0%, 47.0%), cephtazidime (12.0%, 13.5%) chloramphenicol (6.8%, 7.2%), gentamycin (3.0%, 4.0%) neomycin (2.1. 1.8%), calvulanic acid (augmentin (1.4%, 2.2%) and norofloxacin (0.92%, 1.1%). Susceptibility to amikacin, ciprofloxacin, cetfriaxone, ofloxacine, imepenim, cefixime and cefotaxime was 100.0%. The increase in percentage of antibiotic resistant strain might indicate a need for a further prescribing policy for treatment.     

Surface plasmon resonance immunosensor for the detection of Salmonella typhi antibodies in buffer and patient serum

Surface plasmon resonance (SPR) immunosensor using 4-mercaptobenzoic acid (4-MBA) modified gold SPR chip was developed first time for the detection of flagellin specific antibodies of Salmonella typhi (S. typhi). Flagellin protein of S. typhi was prepared by recombinant DNA technology. The modification of gold chip with 4-MBA was in-situ characterized by SPR and electrochemical impedance spectroscopy. By using kinetic evaluation software, K(D) and B(max) values were calculated and found to be 26.3 fM and 62.04 m°, respectively, for the immobilized monoclonal antibody (Moab) of recombinant flagellin (r-fla) protein of S. typhi (r-fla S. typhi). In addition, thermodynamic parameters such as ΔG, ΔH and ΔS were determined first time for r-fla S. typhi and Moab of r-fla S. typhi interactions and the values revealed the interaction between r-fla S. typhi and Moab of r-fla S. typhi as spontaneous, endothermic and entropy driven one. Moreover, healthy human serum samples and patient sera (Widal positive and Widal negative) were subjected to SPR analysis. The present SPR based approach provides an alternative way for S. typhi detection in less than 10 min.     

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.     

Epidemiology of bovine ephemeral fever in Australia 1981-1985

Bovine ephemeral fever is an important viral disease of cattle in Australia. The disease occurred each year, principally in summer and autumn, between 1981 and 1985. Queensland and the northern half of New South Wales were areas of greatest activity with only sporadic cases being reported from the Northern Territory and the northern third of Western Australia. Since 1981, the disease has been endemic in an extensive area of eastern Australia and has tended to occur in widely scattered outbreaks rather than the north-south advancing wave form of the epidemics of 1936-37, 1967-68, 1970-71 and 1972-74. The southernmost outbreaks between 1981 and 1985 were well within the limits of these earlier epidemics. The pattern of disease appears to have become seasonally endemic rather than periodically endemic in the northern two-thirds of eastern Australia. Ephemeral fever was not recorded in Victoria, Tasmania, South Australia or the southern part of Western Australia between 1981 and 1985. The disease was most frequently reported in cattle under 3 years of age, but also occurred in older cattle.     

A computer study of the evolution of aerobic heterotrophic bacterial populations in sewage and river waters

The biodegradation of six surface active agents tested. The biochemical characteristics of the aerobic heterotrophic bacteria present in Montpellier waste waters and in Rhône water, before and after degradation, were studied by a standardized microbiological method. Four hundred strains isolated from these populations were compared to 29 reference strains by computer analysis. The reference strains were first grouped in classes (single linkage). Then the strains were compared first to these classes, and then to each reference strain. Whereas the bacterial populations were widely distributed before biodegradation, after degradation they were restricted to a few prevailing genera:Pseudomonas, Alcaligenes, andKlebsiella.     

Structural basis of typhoid: Salmonella typhi type IVb pilin (PilS) and cystic fibrosis transmembrane conductance regulator interaction

The type IVb pilus of the enteropathogenic bacteria Salmonella typhi is a major adhesion factor during the entry of this pathogen into gastrointestinal epithelial cells. Its target of adhesion is a stretch of 10 residues from the first extracellular domain of cystic fibrosis transmembrane conductance regulator (CFTR). The crystal structure of the N‐terminal 25 amino acid deleted S. typhi native PilS protein (ΔPilS), which makes the pilus, was determined at 1.9 Å resolution by the multiwavelength anomalous dispersion method. Also, the structure of the complex of ΔPilS and a target CFTR peptide, determined at 1.8 Å, confirms that residues 113–117 (NKEER) of CFTR are involved in binding with the pilin protein and gives us insight on the amino acids that are essential for binding. Furthermore, we have also explored the role of a conserved disulfide bridge in pilus formation. The subunit structure and assembly architecture are crucial for understanding pilus functions and designing suitable therapeutics against typhoid. Proteins 2009. © 2009 Wiley‐Liss, Inc.