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Biomedical subjects

S Tabaqchali

Publications and source records attributed to S Tabaqchali.

At least 19 recordsLinked to original sources
PubMed1992

Epidemiological aspects of infections caused by Bacteroides fragilis and Clostridium difficile.

Bacteroides fragilis and Clostridium difficile are two of the most common anaerobes associated with human disease. Studies on the epidemiology of Bacteroides fragilis are limited and are based predominantly on serogrouping, which suggests intraspecies differences. Further studies using newer techniques for typing are required to elucidate the epidemiological characteristics of this important pathogen. By contrast, numerous phenotypic, immunological and molecular methods have been developed for typing and fingerprinting of Clostridium difficile and applied in epidemiological studies to show conclusively that Clostridium difficile is nosocomially acquired and that there is transmission and cross-infection between hospital patients.

Animals↗
PubMed1992

Molecular, immunological, and biological characterization of a toxin A-negative, toxin B-positive strain of Clostridium difficile.

A cytotoxigenic Clostridium difficile strain that fails to produce toxin A but causes hemorrhage and bloody fluid accumulation in ligated ileal loops of rabbits and hemorrhage and diarrhea in hamsters is described. The lack of reaction of DNA from this strain in hybridization studies with a toxin A gene-specific 4.5-kb probe and polymerase chain reaction studies with six toxin A-specific primers indicate the absence of the toxin A gene. The cytotoxin produced by this strain was not responsible for the enterotoxic or hemorrhagic activity and shared characteristics with toxin B, i.e., its cytotoxicity was neutralized by antibodies to toxigenic strains of C. difficile and Clostridium sordellii. Polymerase chain reaction studies with toxin B-specific primers showed that the DNA from this strain produced a 690-bp product in addition to the expected 591-bp product.

Animals↗
PubMed1979

Rapid diagnosis of Bacteroides infections by indirect immunofluorescence assay of clinical specimens.

43 specimens from a variety of sites were directly examined by indirect immunofluorescence assay (I.F.A.) with specific antisera against the capsular polysaccharide of Bacteroides fragilis and pooled antisera against a number of serotypes of Bacteroides sp. (all of the former B. fragilis subspecies). The findings were compared with those of routine anaerobic bacteriology and gas liquid chromatography for short chain fatty acids. Examination by I.F.A. was a sensitive (100%) and specific (90.3%) means of identifying B. fragilis. Use of the pooled serum was sensitive (100%) but less specific (64.3%) than the capsular antiserum (90.3%) although it had the advantage of detecting Bacteroides species other than B. fragilis. The capsular serum I.F.A. gave 9.7% false positives and no false negatives. The predictive value of a positive identification of B. fragilis in a clinical specimen using this anticapsular serum I.F.A. test was 80%; with the pooled Bacteroides group-serum it was 60%. The predictive value of a negative test was 100% for both sera, indicating that a negative I.F.A. test is a reliable index of the absence of Bacteroides from the culture I.F.A. of clinical material provides a rapid (less than 2 h) specific and sensitive means for the diagnosis of B. fragilis infections and would be of use in a clinical laboratory.

Abdomen↗
PubMed1979

The increasing isolation of Serratia species from clinical specimens.

A 14-month survey was undertaken in a diagnostic bacteriology laboratory to determine the incidence of Serratia spp. in routine clinical specimens. Gram-negative organisms with enterobacteria-like colonies were tested by a simple screening procedure. Fifty-eight strains of S. marcescens and two strains of S. liquefaciens were isolated from 59 patients. The strains were usually non-pigmented and exhibited multiple antibiotic resistance. Serotyping and determination of bacteriocine sensitivity patterns revealed that the majority of infections were sporadic, although episodes of cross-infection did occur. S. marcescens was considered to contribute significantly to morbidity and mortality in 53% of patients and appears to be of increasing importance in hospital-acquired infections.

Adult↗
PubMed1979

Vaginal oxytetracycline concentrations.

Although tetracycline preparations are widely used in departments of genitourinary medicine, or sexually transmitted diseases clinics, little is known of the concentrations of these preparations in genital secretions. For this reason a microbiological method was used for estimating oxytetracycline concentrations in vaginal secretions. These concentrations varied from 0.6 to 6.5 microgram/ml in 19 women who had had sexual contact with a man with non-specific urethritis and who were taking oxytetracycline dihydrate 250 mg four times daily. They were well in excess of the minimum inhibitory concentration of oxytetracycline (0.2 microgram/ml) for the strains of Chlamydia trachomatis isolated from the patients with positive culture results. Thus, oxytetracycline 250 mg four times daily appears to be a satisfactory regimen for the treatment of chlamydial genital infection in women.

Adolescent↗
PubMed1979

Anaerobic sepsis.

Anaerobic bacteria are the major residents of the skin and mucous-membrane surfaces, it is reasonable to suspect therefore, that these organisms play a part in the pathological processes associated with disturbances of these sites. The improvements in laboratory methods and the clarification of taxonomy have resulted in an increased awareness of the prevalence and virulence of the non-sporing anaerobic organisms in clinical infections. In this paper, only a brief outline of the types of infections associated with the normal flora and the types of bacteria isolated from these infections are given. Finally some of the pathogenetic mechanisms of anerobic infections are discussed.

Actinomycetales Infections↗
PubMed1979

Abnormal intestinal flora.

The normal small intestine in man usually harbours a sparse microflora consisting of Gram-positive microorganisms derived from the oro-pharynx. The concentrations in the upper jejunum are approximately 10(3)-10(4) organisms/ml, whereas in the ileum the concentrations may be higher and faecal type organisms may also be present, such as Enterobacteria, Bifidobacteria, and Bacteroides in concentrations of 10(5)-10(6) organisms per ml of intestinal aspirate [24, 25]. This situation is well maintained unless the integrity of the small intestine is deranged. There are however, certain conditions in which bacterial proliferation in the lumen of the small intestine may occur and give rise to various metabolic abnormalities [2]. In this paper I would like to list some of these conditions, then describe the type of microflora which colonizes the small intestine, and finally discuss a few aspects of the metabolic consequences of these bacteria.

Actinomycetaceae↗
PubMed1978

A study of the surface and somatic antigens of Bacteroides fragilis.

Antisera against live cultures of 20 strains of Bacteroides fragilis produced in rabbits agglutinated homologous whole-cell as well as O-antigen suspensions with several cross-reactions. Pure specific antisera were produced by absorbing cross-reacting antigens. O-antisera reacted against O-antigens but failed to do so against most whole-cell suspensions, suggesting the presence of surface structures which might have blocked the reactions. The titres of the whole-cell antisera were not significantly higher than those of O-antisera, but the reactions were more definite and easier to read. This system may prove useful in serological studies of B. fragilis.

Antigens, Bacterial↗
PubMed1978

The distribution of Bacteroides fragilis serotypes amongst clinical strains.

Three hundred and twenty-two strains of Bacteroides fragilis isolated from infected patients at three different hospitals were tested against 20 type specific B. fragilis antisera using the tube agglutination technique. Of these strains 41.3% were assigned to a single O-serotype, a further 20.5% were agglutinated by several antisera and could not be classified and the remainder showed no reactions. Three different serotypes were prevalent in the three hospitals and minor geographical variation was observed. No correlation was found between serotypes and the origin of infection, but those from the blood were the most readily typable strains. No correlation was found between serotypes and biotypes of B. fragilis.

Agglutination Tests↗
PubMed1978

Mucosal-associated bacterial flora of the intestine in patients with Crohn's disease and in a control group.

The bacterial flora intimately associated with the intestinal mucosa of patients with Crohn's disease has been examined and compared with the mucosal flora of a control group. Specimens were obtained at operation from patients undergoing intestinal surgery. Whole thickness intestinal sections were taken from the diseased segment and from a portion of uninvolved intestine from patients with Crohn's disease as well as from a control group. A section of each specimen was examined histologically. Twenty-two specimens of Crohn's tissue (12 ileum, 10 colon) and 46 control samples from small and large bowel were examined using strictly anaerobic bacteriological techniques in an anaerobic chamber. Organisms were grown under both aerobic and anaerobic conditions. A mucosal flora was found to exist in all the large bowel samples and in three-quarters of the small bowel samples. It was qualitatively similar in all the samples, consisting mainly of Gram positive bacteria, aerobic Gram negative rods and bacteroides. Greater numbers of bacteria were associated with colonic tissue (10(7) - 10(8) per g) than with tissue from the jejunum (10(3) - 10(4) per g). This difference was statistically significant (p<0.03). Samples from the terminal ileum were quantitatively intermediate between jejunum and colon. There was no statistical difference in the numbers of bacteria associated with Crohn's tissue compared with histologically normal tissue from the same patients and from the control group of patients. Among the bacterial isolates, however, Enterobacteria were more commonly associated with Crohn's tissue.

Aerobiosis↗
PubMed1978

Escherichia coli antibodies in patients with inflammatory bowel disease.

Sera from 30 patients with inflammatory bowel disease (IBD) (16 with Crohn's disease (CD) and 14 with ulcerative colitis (UC) were assayed for the presence of antibodies against 159 Escherichia coli O-antigens and compared with sera from 16 matched control subjects. The majority of patients with IBD had agglutinating antibodies to a higher number of Escherichia coli O-antigens and in higher titres than the control group. The number of positive agglutinins was O-33 mean 13.8 in CD, O-26 mean 7.9 for UC, and O-7 mean 1.5 in controls. Eight patients with IBD and arthropathy had antibodies to fewer O-antigens (O-7 mean 3.2). The antibodies were in the IgG and IgM, in titres corresponding to original values. No specific O-serotypes were associated with IBD. Common serotypes, R-plasmid carrying serotypes, and those associated with shigella-like adult diarrhoea were detected. O14 was detected only in five patients and O119 in none. There was no correlation between the number of Escherichia coli agglutinins and the site and severity of the disease or type of therapy. It is suggested that the presence of the high numbers of Escherichia coli antibodies is secondary to the disease process and is unlikely to be causally involved in the pathogenesis of the disease, but may play a role in the perpetuation of the disease and in the extraintestinal complications.

Adult↗
PubMed1977

Serological studies of Bacteroides fragilis.

Using direct agglutination methods, a simple serological scheme for the classification of Bacteroides fragilis is described. Twenty strains of B. fragilis were selected by a process of sucessive screening from 151 strains obtained from various sources. O-antigens were prepared from the 20 strains, and used to raise antisera in rabbits. Each of the 20 antisera reacted with its homologous antigen and eight antisera cross-reacted with other subspecies. These cross-reactions were successfully removed after absorption of the antisera with the cross-reacting antigens, resulting in 19 type-specific antisera, titres ranging from 40 to 320, and 19 distinct serotypes of B. fragilis. There was no correlation between the antigenic and the biochemical characteristics of these strains and no cross-reactions occurred with other gram-negative anaerobes, B. melaninogenicus, Sphaerophorus necrophorus and Fusobacterium necrogenes.

Agglutination Tests↗
PubMed1977

Escherichia coli serotypes throughout the gastrointestinal tract of patients with intestinal disorders.

The O and H serotypes of Escherichia coli that were present along the entire length of the gastrointestinal tract of patients with small intestinal bacterial overgrowth were studied. Multiple sero- and biotypes were represented, although usually a single serotype predominated in each patient. In a number of cases the different O:H serotypes were antigenically related indicating that antigenic degradation was occurring. The serotypes isolated from the stomach and small intestine were represented in the faeces. In general, within the limitations of this study, there appears to be a stable ecosystem in each patient and it may require specific oral antibiotics to alter it.

Adult↗