Immunological studies in typhoid fever. II. Cell-mediated immune responses and lymphocyte subpopulations in patients with typhoid fever.

The development of the cell-mediated immune response (CMIR) to antigens prepared from Salmonella typhi was investigated in patients suffering from typhoid fever and in normal healthy subjects. The leucocyte migration inhibition test, blast transformation of lymphocytes and active rosette-forming cells were used for detecting CMIR. Peripheral blood lymphocytes were analysed for the numbers and proportions of B lymphocytes, T lymphocytes and their subpopulations with receptors for IgM (T micro) or IgG (T gamma) and cells with Fc receptors for IgG. These parameters were correlated with the duration and the severity of illness. The uncomplicated cases of typhoid fever were found to have an intact CMIR as compared to the complicated cases. The ratio of T lymphocyte subpopulations was grossly imbalanced in typhoid patients, the numbers of T lymphocytes and their subpopulations were further altered in he complicated cases as compared to uncomplicated cases. The present study demonstrates a depressed state of CMIR in complicated patients with typhoid fever. CMIR may thus emerge as the cardinal point for recovery in typhoid fever rather than the specific antibodies. The study further demonstrates that imbalance within the subsets of T lymphocytes may be responsible for the depressed state of CMIR in complicated cases of typhoid fever.     

Immunological studies in typhoid fever. I. Immunoglobulins, C3, antibodies, rheumatoid factor and circulating immune complexes in patients with typhoid fever.

The development of O, H and Vi antibodies to Salmonella typhi antigens, immunoglobulins and C3 levels, and the presence of rheumatoid factor and circulating immune complexes were determined in the sera of patients with typhoid fever and appropriate age and sex-matched controls. IgM, and both O and H antibodies were raised in typhoid patients. Rheumatoid factor, a possible indicator of persistent circulating immune complexes, was also present in these patients. Immune complexes were more often present in patients with typhoid fever than in controls, their presence was much more marked in complicated cases of typhoid fever. A high ratio of alpha 1-antitrypsin to C3 was found in these patients suggesting complement consumption.     

Immune response to the iron-deprivation-induced proteins of Salmonella typhi in typhoid fever.

Iron starvation conditions limited the growth of Salmonella typhi, as evidenced by an increase in the lag phase of a culture and a decrease in the number of bacteria reached in the stationary phase. The analysis of the outer membrane of bacteria grown under these conditions identified new protein components with apparent molecular weights of 83,000, 78,000, and 69,000. The extent of induction of these proteins was regulated by increased iron deprivation. Immunoblot analysis showed that the serum of patients with typhoid fever exhibited an immunoglobulin G response to these iron-deprivation-induced proteins. The results of bioassays and DNA-DNA hybridization experiments indicated that pathogenic strains of S. typhi produced enterochelin but not aerobactin. Immunodetection with an anti-FepA antiserum confirmed that one of the induced proteins is the S. typhi analog of the Escherichia coli fepA gene product. These studies suggest a role for iron uptake in the pathogenesis of typhoid fever and confirm the immunogenicity of some of the outer membrane proteins of this pathogen.     

Study of clinical profile and antibiotic response in typhoid fever

The objective of the present study is to evaluate the clinical profile and pattern of various drugs used in the treatment of typhoid fever. A retrospective analysis of adult patients suffering from typhoid fever was done at Kasturba Medical College hospital, Attavar during the year 1999-2001. Diagnosis of patients was based on clinical features, widal test and blood culture. The sensitivity pattern of isolates from blood culture was recorded. The mode of presentation, clinical course, treatment history, laboratory investigations reports, antibiotic administered, response to therapy and the complications were recorded. Total number of 44 cases of typhoid fever were studied. Out of these 21(47.7%) were males and 23(52.3%) were females. Average age of presentation was 23.9 years. Average duration of hospital stay was 10.8 days. Fever was present in all patients. Resistance of S. typhi to amoxicillin, chloramphenicol, ampicillin and co-trimoxazole were significantly high. Ciprofloxacin also showed resistance in 18.1% of cases. Sensitivity to cephalosporin was 100% in our study. Ciprofloxacin was the most commonly used antibiotic in our study (23 patients). Chloramphenicol alone was used in 2 patients and in 3 patients it was given after 6 days of ciprofloxacin treatment. Third generation cephalosporins (ceftriaxone) alone were used in 16 patients. Indiscriminate use of drugs in typhoid fever should be discouraged. Appropriate antibiotic as indicated by sensitivity tests should be employed to prevent the development of resistant strains of S. typhi.     

Changing characteristics of typhoid fever in Taiwan.

Typhoid fever, a systemic disease caused by Salmonella typhi, is classically characterized by fever and abdominal symptoms. Although now considered uncommon, it seems to have re-emerged in Taiwan in recent years. We conducted a retrospective study of the clinical characteristics and microbiologic findings in 24 confirmed cases of typhoid fever treated over a 7-year period at a medical center in northern Taiwan. There were 11 males and 13 females, including 15 adults (over 18 years in age) and 9 children. Their mean age was 24.7 years (range, 9 months to 58 years). Twelve patients had recently returned from abroad, mostly from Southeast Asia. The most common complaints were fever (24/24), diarrhea (18/24), abdominal pain (10/24), and cough (10/24). The average duration of fever before diagnosis was 14.1 days, with a maximum of 30 days. Relative bradycardia was noted in 6 patients. Leukopenia was noted in 2 patients. S. typhi was isolated from blood culture in 20 cases, from stool culture in 3 cases, and from bone marrow culture in 1 case. Widal test was only positive initially in 7/18 cases. Fever of unknown origin was the most common initial diagnosis. Typhoid or enteric fever was impressed initially in only 2 cases. Almost all isolates of S. typhi were susceptible to antibiotics currently used for typhoid fever, with only 1 isolate resistant to chloramphenicol. All patients survived after antibiotic treatment. Only 1 patient developed recurrence after a 10-day course of ceftriaxone. In conclusion, the diagnosis of typhoid fever is often challenging due to non-specific symptoms and lack of an immediate confirmatory test. It is important to include this disease in the differential diagnosis of febrile patients with abdominal symptoms.     

Immunoblot detection of class-specific humoral immune response to outer membrane proteins isolated from Salmonella typhi in humans with typhoid fever

The studies reported here were undertaken to assess the ability of the outer membrane proteins (OMPs) of Salmonella typhi to induce a humoral immune response in humans with typhoid fever. OMPs were isolated with the nonionic detergent Triton X-100 and were found to be contaminated with approximately 4% lipopolysaccharide. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis patterns showed protein bands with molecular size ranges from 17 to 70 kilodaltons; the major groups of proteins were those that correspond to the porins and OmpA of gram-negative bacteria. Rabbit antiserum to OMPs or to S. typhi recognized OMPs after absorption with lipopolysaccharide. Sera from patients with typhoid fever contained immunoglobulin M antibodies which reacted with a protein of 28 kilodaltons and immunoglobulin G antibodies which reacted mainly with the porins, as determined by immunoblotting. These results indicate that the porins are the major immunogenic OMPs from S. typhi and that the immune response induced in the infection could be related to the protective status.     

Simultaneous induction of rheumatoid factor- and antigen-specific antibody-secreting cells during the secondary immune response in man.

The production of anti-tetanus toxoid antibody and rheumatoid factor (RF) by individual peripheral blood mononuclear cells (PBMC) was studied at various times after booster immunization of healthy volunteers with tetanus toxoid (TT). TT-specific antibody-secreting cells and RF-secreting cells were assayed by the enzyme-linked immunospot (ELISPOT) assay. Cells obtained 5-9 days after immunization were found to spontaneously secrete TT-specific antibodies. This response was specific for the immunogen, was abrogated by cycloheximide and accounted for most of the immunoglobulins produced. TT-specific antibody-secreting cells were found concomitantly with cells secreting RF, mainly of the IgM isotype. Elevated levels of circulating immune complexes (CIC) containing IgG and C3 were observed shortly before the appearance of both TT-specific antibody-secreting cells and IgM RF-secreting cells. Thus, after booster immunization with TT, two major subpopulations of immunoglobulin-secreting cells appear concomitantly in the peripheral circulation: a population of cells secreting TT-specific antibody and a population of cells secreting IgM RF. It is suggested that RF production in man represents a physiological event which might be triggered by IgG-containing immune complexes formed during a secondary immune response.