Clostridium difficile and enterotoxigenic Bacteroides fragilis strains isolated from patients with antibiotic associated diarrhoea

From the fecal samples of 332 patients with a clinical diagnosis of antibiotic associated diarrhoea (AAD), 131 Clostridium difficile strains were isolated. For detection of toxin A in the isolated strains the enzymatic immunoassay was used. The cytopathic effect was determined on McCoy cell line. PCR was used for the detection of non-repeating and repeating sequences of toxin A gene and non-repeating sequences of toxin B gene. One hundred and six isolated C. difficile strains were TcdA(+)TcdB(+), 10 strains TcdA(-)TcB(+) and 15 were non-toxigenic TcdA(-)TcdB(-). Out of the same fecal samples 50 Bacteroides fragilis strains were isolated. All B. fragilis strains were tested in PCR reaction for fragilysine gene detection (bft). In 9 strains (18%) this gene was detected and the strains could be assumed as enterotoxigenic Bacteroides fragilis (ETBF). In 4 fecal samples toxigenic C. difficile (TcdA(+)TcdB(+)) was found simultaneously with ETBF. One sample contained C. difficile (TcdA(-)TcdB(+)) and ETBF. Out of 4 fecal samples only ETBF was isolated. The cytotoxicity of ETBF strains was tested on HT29/C1 human colon carcinoma cell line. The cytotoxicity titer in the range of 20 and 80 was observed.

[Adhesion of human granulocytes and T lymphocytes to vascular endothelial cells after stimulation with Bacteroides fragilis endotoxin and enterotoxin]

The aim of presented study was to estimates the number of human granulocytes and T lymphocytes adhering to 1 mm2 of vascular endothelial cell culture stimulated by Bacteroides fragilis endotoxins (LPS) and enterotoxin (BFT). HMEC-1 cells were activated with bacterial preparations at the concentration of 10 (micrograms/ml for 4 and 24 hours. Granulocytes and T lymphocytes were isolated from peripheral blood of healthy blood donors. The adhesion tests of granulocytes and adhesion tests of resting and activated with PMA (at the concentration of 10 ng/ml) T lymphocytes to the non-stimulated and stimulated by B. fragilis compounds (LPS and BFT) vascular endothelium were performed. The number of viable leukocytes, which adhered to the endothelium, was determined using inverted microscope (magnification 200x). The results were presented as the number of viable cells adhering to 1 mm2 of the endothelial cell culture. The results of experiments indicate that granulocytes and T lymphocytes (resting and after activation with PMA even in greater number) adhere to the endothelial cells stimulated by B. fragilis endotoxins and enterotoxin. B. fragilis toxins are weaker stimulants of human leukocyte adhesion to the HMEC-1 cells than E. coli O55:B5 LPS. B. fragilis LPS and BFT preparations stimulate endothelial cells to the adhesion of granulocytes in similar manner, whereas the activation of vascular endothelium to the adhesion of T lymphocytes is differentiated.

[The effect of metronidazole on stimulation of adhesion molecule expression on the surface of vascular endothelial cells by Bacteroides fragilis endotoxins and enterotoxin]

The influence of metronidazole on the level of expression of adhesion molecules ICAM-1, VCAM-1 and E-selectin on the surface of vascular endothelial cells activated with B. fragilis endotoxins and enterotoxin was examined. Three enterotoxigenic (ETBF) strains and one nonenterotoxigenic (NTBF) strain were used for lipopolysaccharide extraction. Enterotoxin was prepared from the culture supernatant of the reference B. fragilis ATCC 43858 strain. Expression of adhesion molecules on vascular endothelial cells (HMEC-1 cell line) was determined after their stimulation with bacterial compounds at the concentration of 10 micrograms/ml in the presence of metronidazole at the concentration of 4 micrograms/ml. Endothelial cells were activated for 4 hours (E-selectin expression) and for 24 hours (ICAM-1 and VCAM-1 expression). Adhesion molecules were detected in immunoenzymatic test (ELISA) with mouse, monoclonal antibodies against human ICAM-1, VCAM-1 and E-selectin. The results of experiments suggest, that metronidazole enhances the expression of examined adhesion molecules on endothelial cells. This antimicrobial agent causes some changes in the expression of endothelial ICAM-1, VCAM-1 and E-selectin stimulated by B. fragilis endotoxins and enterotoxin.

[Effect of clindamycin on stimulation of cell adhesion molecules by endotoxins and enterotoxin of Bacteroides fragilis strains]

The influence of clindamycin on expression of B. fragilis endotoxins (LPS) and enterotoxin stimulated cell adhesion molecules: ICAM-1, VCAM-1 and E-selectin on HMEC-1 (human microvascular endothelial cell line) was tested. Lipopolysaccharides from four Bacteroides fragilis strains: one nonenterotoxigenic (NTBF) and three enterotoxigenic (ETBF) were extracted by hot phenol-water method and purified. B. fragilis enterotoxin was prepared according to the method described by van Tassel et al. (1992). All bacterial preparations were used for stimulation at concentration 10 micrograms/ml. Clindamycin was used in concentration of 2 micrograms/ml. The influence of antimicrobial agent on the endotoxins and enterotoxin stimulation and expression of adhesion molecules was tested by ELISA, using monoclonal mouse anti-human antibodies (Genzyme, USA). Peroxidase-conjugated rabbit anti-mouse immunoglobulins (DAKO A/S Denmark) and OPD (Sigma USA) were used. The coloured reaction product was measured by reading the absorbance at 492 nm in SPECTRA II reader (SLT, Austria). It was observed that clindamycin influenced the expression of cell adhesion molecules on resting cell line. HMEC-1 cells stimulated with Bacteroides fragilis LPS preparations have suppressive effect on ICAM-1 expression. ICAM-1 expression was augmented when stimulated with Tox 1 and Tox 2 preparations. Clindamycin augmented the VCAM-1 expression in tests with all bacterial preparations. All used bacterial preparations of Bacteroides fragilis LPS and enterotoxin enhanced the expression of E-selectin with exception of LPS of NTBF strain.

[Antagonistic activity of Lactobacillus bacteria strains against anaerobic gastrointestinal tract pathogens (Helicobacter pylori, Campylobacter coli, Campylobacter jejuni, Clostridium difficile)]

Antagonistic activity of Lactobacillus strains has been known for some time. This property is connected with production of many active substances by lactobacilli e.g., organic acids and bacteriocin-like substances which interfere with other indigenous microorganisms inhabiting the same ecological niche, including also anaerobic gastrointestinal tract pathogens. Growing interest of clinical medicine in finding new approaches to treatment and prevention of common inflammatory infections of the digestive tract resulted in studies on a possible usage of lactic acid bacteria. Last years, several in vitro and in vivo experiments on antagonism of different Lactobacillus strains against Helicobacter pylori and Clostridium difficile were performed. These observations had been done on already established, well known probiotic Lactobacillus strains. We tested antibacterial activities of Lactobacillus strains isolated from human digestive tract. As indicator bacteria, four species known as anaerobic bacterial etiologic agents of gastroenteric infections: Helicobacter pylori, Campylobacter jejuni, C. coli and Clostridium difficile were used. Some of them were obtained from international collections, others were clinical isolates from specimens taken from patients with different defined gastrointestinal infections. We used a slab method of testing inhibitory activity described in details previously. Following conclusions were drawn from our study: All tested human Lactobacillus strains were able to inhibit the growth of all strains of anaerobic human gastrointestinal pathogens used in this study. Inhibitory activities of tested Lactobacillus strains against Helicobacter pylori, Campylobacter spp., and Clostridium difficile as measured by comparing mean diameters of the inhibition zones were similar. Differences in susceptibility of individual indicator strains of Campylobacter spp. and Clostridium difficile to inhibitory activity of Lactobacillus strains were small. A similar mechanism of inhibition of anaerobic bacteria by lactobacilli is postulated.

[Analysis of fatty acids from lipopolysaccharides of Bacteroides thetaiotaomicron and Bacteroides fragilis]

The aim of this study was to determine and to compare fatty acids occurring in lipopolysaccharides (LPS) isolated from B. thetaiotaomicron and B. fragilis strains of different origin. Lipopolysaccharides of three B. thetaiotaomicron strains and four B. fragilis strains were isolated by phenol-water extraction according to the procedure of Westphal and Jann (1965). Water-phase LPS fractions were then treated with nucleases and purified by ultracentrifugation as described by Gmeiner (1975). Fatty acid methyl esters, obtained by methanolysis of LPS, were analysed in gas-liquid chromatography combined with mass spectrometry (GLC-MS). Trimethylsilylated hydroxyl groups of fatty acid methyl esters were identified with GLC-MS using a method of selective ion monitoring (SIM). Lipopolysaccharides of B. thetaiotaomicron and B. fragilis strains contained long-chain (15-18 carbon atoms) fatty acids. The broad spectrum of simple long-chain and branched-chain fatty acids as well as 3-hydroxy fatty acids were detected. The main fatty acid of analyzed bacterial species was 3-hydroxy-hexadecanoic acid (3OH C16:0). Several 3-hydroxy fatty acids were detected in LPS of examined strains. Fatty acids occurring in LPS of B. thetaiotaomicron and B. fragilis strains appeared to be qualitatively similar. Quantitative differences in fatty acids composition of lipopolysaccharides isolated from strains of different origin were observed.

Clonal dissemination of a toxin-A-negative/toxin-B-positive Clostridium difficile strain from patients with antibiotic-associated diarrhea in Poland

OBJECTIVE

To determine the incidence of toxin-A-negative/toxin-B-positive Clostridium difficile strains and their genetic relatedness in the feces of patients suffering from antibiotic-associated diarrhea (AAD) in Polish hospitals.

METHODS

C. difficile strains were cultured from patients' stool samples. The present study characterises these strains with respect to their cytopathogenicity on McCoy cells and the absence of toxin A despite a functional toxin B as determined with commercial test kits (Culturette Brand Toxin CD-TCD toxin A test and C. difficile Tox A/B test). In addition, PCR using different primer pairs aiming at non-repeating or repeating regions of the toxin A and B genes were used to confirm the findings. All toxin A(-)B(+) strains were genetically characterised by random amplification of polymorphic DNA (RAPD) analysis, PCR ribotyping and, in part, pulsed-field gel electrophoresis (PFGE) of DNA macrorestriction fragments.

RESULTS

We here present the presence of 17 toxin A(-)B(+) strains among 159 C. difficile strains (11%) isolated from fecal samples from 413 patients with antibiotic-associated diarrhea. All 17 strains possessed the toxin B gene, demonstrated a cytopathogenic effect on the McCoy cells, and were positive in the Tox A/B test. Molecular typing of these 17 C. difficile strains revealed that 7 of 17 (41%) toxin A(-)/B(+) C. difficile strains could not be discriminated. It appeared that these strains had a genotype that could not be distinguished from that of a Japanese control strain.

CONCLUSION

Our observations imply that a particular genotype of toxin A(-)B(+) C. difficile has spread extensively, not only in Poland but possibly even worldwide.

[Intestinal flora of patients with suspected antibiotic associated diarrhea (AAD). I. Clostridium perfringens]

Stool samples of 158 patients suspected of antibiotic-associated diarrhoea (AAD) were studied. Toxin A of C. difficile and enterotoxin of C. perfringens were detected in stool samples by immunoenzymatic assays and PCR. In 35 stool samples toxin A of C. difficile was detected and in 48 cases (30%) C. difficile strains were cultured from 21 stool samples (13%). The presence of the cpe gene of C. perfringens, enabling the production of enterotoxin, could not be detected by PCR, both in stool samples and in isolated strains, using ent 1 and ent 2 primer pairs. C. difficile and C. perfringens were isolated from the same stool samples in 4 cases. From stool samples of two patients with AAD C. perfringens strains, thermoresistant spores were cultured.

[Adhesion of human T lymphocytes and granulocytes to endothelial cells stimulated by cell-surface antigens of Bacteroides thetaiotaomicron]

The aim of this study was to assay the degree of human T lymphocyte and granulocyte adhesion to the vascular endothelial cells stimulated by Bacteroides thetaiotaomicron lipopolysaccharides, components of LPS and capsular polysaccharide. HMEC-1 cells were activated with bacterial preparations in concentration 10 micrograms/ml for 4 and 24 hours. T lymphocytes and granulocytes were isolated from peripheral blood of healthy blood donors. Thereafter, the adhesion tests of granulocytes and adhesion tests of non-activated and activated with PMA (in concentration 10 ng/ml) T lymphocytes to the resting and stimulated vascular endothelium were performed. The number of viable cells, which adhered to the endothelium, was determined using inverted microscope (magnification 200x). The results were presented as the number of viable cells adhering to 1 mm2 of the endothelial cell culture. The obtained results indicate that granulocytes and T lymphocytes (resting and activated with PMA) adhere to the endothelial cells stimulated by B. thetaiotaomicron cell-surface antigens. B. thetaiotaomicron lipopolysaccharides and capsular polysaccharide are weaker stimulants of human leukocyte adhesion to the HMEC-1 cells than E. coli O55:B5 LPS.

Acute appendicitis: the role of enterotoxigenic strains of Bacteroides fragilis and Clostridium difficile

BACKGROUND

The aim of this study was to investigate whether there is a relationship between enterotoxin-producing B. fragilis strains and toxigenic C. difficile strains and the pathogenesis of acute appendicitis.

MATERIAL AND METHODS

Post-appendectomy tissues from 34 patients with histopathologically confirmed phlegmonous or gangrenous appendicitis were studied.

RESULTS

Among 86 anaerobes isolated, the B. fragilis group was most frequently isolated: 34 B. fragilis strains were cultured from 21 post-appendectomy tissues. Two enterotoxin-producing B. fragilis strains were found. Enterotoxin titers (1:10 and 1:160, respectively) were measured on HT29/C cells. The presence of the enterotoxin gene was confirmed by PCR in DNA extracted from both strains. Among 21 DNA samples isolated from those post-appendectomy tissues from which B. fragilis strains were cultured, the presence of the enterotoxin gene was confirmed in only one case (the corresponding B. fragilis strain enterotoxin titer was 1:160). A unique toxigenic C. difficile strain was also cultured from the tissue of an adult patient with gangrenous non-perforated appendicitis. The presence of toxin A and toxin B genes was confirmed by PCR in DNA extracted from the C. difficile strain, but these genes were not found in the DNA extracted from the corresponding tissue.

CONCLUSION

The presence of enterotoxigenic B. fragilis and toxigenic C. difficile strains was shown in post-appendectomy tissue from patients with phlegmonous and gangrenous appendicitis, and the B. fragilis enterotoxin gene was detected directly in the corresponding tissue. Further investigations (including immunologic aspects) require to confirm the role of these toxins in pathogenesis of acute appendicitis.

In vitro antibiotic susceptibility of Bacteroides fragilis strains isolated from excised appendix of patients with phlegmonous or gangrenous appendicitis

Out of 34 studied after-appendectomy tissues of adult and child patients 86 different strains of anaerobes were isolated. The antibiotic susceptibility of 30 isolated B. fragilis strains was tested using E tests. All studied strains were sensitive to imipenem, clindamycin and penicillin/tazobactam. Sensitivity to penicillin and cefoxitin was variable among these strains. One strain resistant to metronidazole (MIC--256 mg/L) and 3 strains with increased MIC to metronidazole were detected. Most of isolated strains were beta-lactamase producers.

Search for enterotoxin gene in Bacteroides fragilis strains isolated from clinical specimens in Poland, Great Britain, The Netherlands and France

BACKGROUND

Bacteroides fragilis is a member of normal human flora and well known pathogenic agent. This bacterium produces many virulence factors. In 1984 new virulence factor--enterotoxin was described. The aim of the study was to search for enterotoxin gene in B. fragilis strains isolated from clinical specimens.

MATERIAL AND METHODS

Strains isolated in Poland, Great Britain, France and the Netherlands were cultured on BBE medium. For DNA isolation Genomic DNA PREP PLUS isolation kit manufactured by A&A Biotechnology (Poland) was used. In order to detect enterotoxin (fragilysin) gene, polymerase chain reaction (PCR) was applied utilizing the following primers: 404 (GAG CGG AAG ACG GTG TAT GTG ATT TGT) and 407 (TGC TCA GCG CCC AGT ATA TGA CCT AGT). DNA obtained from bacterial cells was amplified in thermocycler Techne. The amplification products were detected by the electrophoresis in 1% agarose gel.

RESULTS

Among 65 investigated B. fragilis strains, the enterotoxin gene was detected in DNA isolated from 12 strains.

CONCLUSION

The enterotoxin producing B. fragilis strains were detected among strains isolated from different clinical specimens in Poland, Great Britain, the Netherlands and France.

[Stimulation of adhesion molecules on vascular endothelium by capsular polysaccharide, lipopolysaccharide and components of lipopolysaccharide from Bacteroides thetaiotaomicron]

The aim of this study was to assay the influence of capsular polysaccharide (CPS), lipopolysaccharide (LPS) and components of B. thetaiotaomicron lipopolysaccharide--polysaccharide part (PS) and lipid part (lipid A) on the expression of adhesion molecules associated with inflammation (ICAM-1, VCAM-1, E-selectin) on the surface of vascular endothelial cells. Capsular polysaccharide was isolated by the method of Poxton and Ip (1981). Lipopolysaccharides were extracted using the hot phenol-water method (Westphal and Jann, 1965). Components of LPS were prepared by mild acid hydrolysis of lipopolysaccharide. Experiments with bacterial compounds at concentrations 10, 1, 0.1 and 0.01 (mg/ml) were performed on HMEC-1 cell line (human dermal microvascular endothelial cells). Immunoenzymatic ELISA test with mouse monoclonal antibodies against human: ICAM-1, VCAM-1 and E-selectin was applied to determine adhesion molecules. Resting HMEC-1 and E. coli O55:B5 LPS were used as controls in each experiment. Lipopolysaccharides were the strongest stimulants of endothelial adhesion molecules. Capsular polysaccharide caused the expression of three adhesion molecules, but only at the highest concentration (10 mg/ml). The stimulatory activities of LPS lipid components were much higher than the activities of polysaccharide parts. PS preparations did not reveal the property of adhesion molecule stimulation or their activities were weak. The activity of B. thetaiotaomicron cell-surface antigens in the process of adhesion molecule stimulation on vascular endothelium was lower than the activity of E. coli LPS.

[Beta-lactamases with a wide substrate spectrum in gram negative strictly anaerobic rods]

This study was performed to determine the susceptibility of the clinical strains of Gram-negative strictly anaerobic rods to newer beta-lactam antibiotics. Also, the trial was undertaken to detect strains producing extended-spectrum beta-lactamases (ESBLs) and inducible beta-lactamases (IBLs) among Bacteroides spp. and Prevotella spp. rods isolated from hospitalized patients. One hundred strains of Gram-negative, obligatory anaerobic rods were applied in the study. The strains were identified in automatic ATB system using API 20 A strips. beta-lactamase-positive strains were determined with disc nitrocefin test. ESBL-producing strains were detected with double disc test according to Jarlier et al. (1988). Clavulanate was applied as the inhibitor of these beta-lactamases (AMO/CLAV disc). ESBL-positive strains were confirmed with the use of E test (TZ/TZL strip). Inducible beta-lactamases were determined by double disc method according to Sanders and Sanders (1979). Cefoxitin was the inducer of these beta-lactamases (FOX disc). Among 93 Bacteroides spp. strains and 7 Prevotella spp. strains, 91 strains (91%) produced beta-lactamases. Two ESBL-producing strains (2%) were detected. Strains producing inducible beta-lactamases (IBL) were not found. A high activity of the examined beta-lactam antibiotics against strains of Gram-negative anaerobes was found. The majority of strains were susceptible to piperacillin (95%), piperacillin combined with tazobactam (99%), ticarcillin combined with clavulanic acid (99%), meropenem (97%) and imipenem (99%). The obtained results indicate the necessity of ESBL determination among strains of the genus Bacteroides, isolated from clinical specimens. Newer beta-lactam antibiotics, especially penicillins in combination with beta-lactamase inhibitors and carbapenems, are useful in empiric therapy of infections caused by Bacteroides spp. and Prevotella spp. anaerobic rods.

[Enterotoxin-producing Bacteroides fragilis strains isolated from horses]

Seven Bacteroides fragilis strains were cultured from samples collected from horses. From all the tested strains, as well as from the reference B. fragilis strains: enterotoxigenic NCTC 11925 and nonenterotoxigenic IPL 323 strain, DNA was isolated using Genomic DNA PREP PLUS isolation kit manufactured by A&A Biotechnology (Poland). To detect the enterotoxin (fragilysin) gene, polymerase chain reaction (PCR) was applied, using the following starters: 404 (GAG CCG AAG ACG GTG TAT GTG ATT TGT) and 407 (TGC TCA GCG CCC AGT ATA TGA CCT AGT). DNA obtained from bacterial cells was amplified in a thermocycler (Techne). The temperature profile was as follows: 1 cycle (4 min. 94 degrees C), 40 cycles (1 min. 94 degrees C, 1 min. 52 degrees C, 1 min. 74 degrees C). Amplification products were detected by electrophoresis in agarose gel (1%) with ethidium bromide added. The presence of the fragilysin gene was detected in two strains. Among the strains isolated from horses enterotoxin gene-possessing Bacteroides fragilis strains (ETBF) can be detected.

[Toxins of Bacteroides fragilis and Bacteroides thetaiotaomicron rods as stimulators of adhesion molecule expression on the surface of vascular endothelial cells]

Lipopolysaccharides from four Bacteroides fragilis strains: one nonenterotoxigenic (NTBF) and three enterotoxigenic (ETBF), and from three B. thetaiotaomicron strains were extracted by hot phenol-water method and purified. B. fragilis enterotoxin was prepared according to the procedure of van Tassell et al. (1992). The influence of the examined toxins on the expression of adhesion molecules: ICAM-1, VCAM-1 and E-selectin on HMEC-1 (human dermal microvascular endothelial cells) was assayed in ELISA test with monoclonal antibodies. Four concentrations of toxins were applied: 0.01, 0.1, 1.0 and 10.0 (micrograms/ml). Endothelial cells were activated for 24 hours (ICAM-1 and VCAM-1 expression) and for 4 hours (E-selectin expression). The coloured product of immunoenzymatic reaction was measured by reading the absorbance at wavelength 492 nm. Two controls were performed in each experiment: with resting HMEC-1 and E. coli O55:B5 LPS (Sigma, USA). Bacteroides fragilis and B. thetaiotaomicron lipopolysaccharides stimulated three adhesion molecules under investigation. Their activity was comparable, but weaker than the activity of E. coli O55:B5 LPS. ICAM-1 was the most stimulated molecule. B. fragilis enterotoxin induced two adhesion molecules: VCAM-1 and E-selectin demonstrating weaker stimulatory activity than E. coli LPS. Stimulation of adhesion molecules on vascular endothelial cells should be considered to be a biological activity of B. fragilis and B. thetaiotaomicron endotoxins and B. fragilis enterotoxin.

[Effect of suprainhibitory (supra-MIC) concentration of clindamycin on endotoxin release from Bacteroides fragilis]

The aim of this work was to determine the influence of clindamycin at concentration 100 x MIC on the growth of culture and the induction of endotoxin release from the cells of standard B. fragilis IPL E 323 strain. The antibiotic was added to 24-hour culture of the strain in BHI medium (time 0), its final concentration was 12.5 mg/l. The samples for further examinations were collected at time 0 and after 1, 2, 3 and 24 hours of continued incubation. At the same time the strain was cultured in a medium without the antibiotic. The optical density (OD 420 nm) of each sample was determined, they were centrifuged (2000 x g, 10 min), the supernatants were filtered (0.45 micron filters) and concentrated three times (5000 D ultrafilters). Two serological methods were applied to detect the presence of endotoxin in filtrates of culture medium: immunoelectroprecipitation (IEP) and immunoenzymatic assay (dot-ELISA) with rabbit anti-IPL E 323 immune serum. The results of experiments performed with filtrates of culture without the antibiotic indicate that standard B. fragilis IPL E 323 strain liberates endotoxin spontaneously to the culture medium. Single suprainhibitory dose of clindamycin at concentration 100 x MIC inhibits the growth of examined strain and does not cause augmented release of endotoxin from B. fragilis cells in vitro.

[Isolation of toxigenic strains of Clostridium difficile and enterotoxin producing Bacteroides fragilis from fecal specimens of patients suspected of antibiotic associated diarrhoea]

Fifty faecal samples from patients suspected of AAD (antibiotic associated diarrhoea) were studied for Clostridium difficile and enterotoxin producing Bacteroides fragilis (ETBF). Using TCD (Becton-Dickinson) and C. difficile Toxin A test (Oxoid) in 34% of specimens the presence of toxin A was detected. From all specimens 25 C. difficile strains were isolated. All isolated strains produced toxin B in vitro which was shown in Mc Coy cytotoxicity test. Eighteen strains only were toxin A positive in vitro. From all isolated C. difficile strains 28% were tox A (-) tox B (+). By means of PCR presence of toxin A and toxin B genes was tested directly in faecal samples and in strains. From the same 50 faecal samples 17 B. fragilis strains were isolated. Four of them produced the enterotoxin (fragilisin) which was detected on the HT 29/C1 cell line. Genes of fragilisin were found in strains and directly in faecal samples. Toxin producing C. difficile and B. fragilis (ETBF) together were found in 3 samples. From one faecal sample only ETBF was cultured.

Evaluation of different methods for detection of Clostridium difficile toxins in Poland

The aim of this study was to compare different methods for C. difficile toxins detection. Fifty three stool samples taken from patients with antibiotic-associated diarrhoea were studied. TCD toxin A EIA (Becton Dickinson, USA), Tox A/B ELISA test (TechLab, USA), cytotoxicity and neutralization assay on McCoy cells and PCR for detection of both toxin A and B genes were performed in vivo (in stool samples) and in vitro (in isolated strains). Reference toxigenic and nontoxigenic and two Japanese toxin A-negative and toxin B-positive C. difficile strains were used as a controls. TCD toxin A EIA detected in vivo only 19 positive samples. Tox A/B test detected 52 positive samples out of 53 studied. All 53 stool samples were C. difficile culture positive (53 strains were cultured). Toxin B was detected in 52 strain-supernatants and in all controls (except the nontoxigenic one). Both toxin A and B genes were detected by PCR in all 53 isolated strains, Japanese and reference strain (except the nontoxigenic one). In vitro toxin A was detected by TCD toxin A EIA in 42 strains. These results were compared with those obtained in Tox A/B ELISA test. We observed 52 positive strains. Toxigenic reference strain and two Japanese toxA(-)/toxB(+) strains were also positive. Only 2 negative results were obtained with the nontoxigenic reference strain and unique nontoxigenic isolated strain. Tox A/B ELISA test seems to be the best for detection of C. difficile toxins in vivo and in vitro. Test avoids the false-negative results in the case of presence of toxin A-negative and toxin B-positive strain.

Antigenic properties of LPS extracted from Bacteroides fragilis enterotoxin producing strains

Antigenic properties of enterotoxigenic Bacteroides fragilis (ETBF) strains isolated in Poland were compared with reference strains. The agglutination and passive hemagglutination, SDS-PAGE analysis and immunoblotting tests as well as analyses of sugars and fatty acids were performed with lipopolysaccharide (LPS) preparations obtained from water-phase of phenol-water extracts. Some differences in serological reactivity between ETBF antigens were observed. The antigen of the NTBF (nonenterotoxigenic) reference strain IPL E-323 expressed weak cross-reactivity with sera against whole cells of ETBF strains in serological tests. There were some differences observed between ETBF and NTBF strains in fatty acids and sugar composition. The LPS preparations probably possess a common core structure and the O-specific polysaccharides of variable chain length.

Adhesion molecule expression stimulated by Bacteroides thetaiotaomicron cell-surface antigens

Bacteroides thetaiotaomicron, a Gram-negative anaerobic rod belonging to the Bacteroides fragilis group (BFG), is involved in many systemic and local, most frequently suppurative infections in man. The cell envelope of these rods is composed of two carbohydrate-containing antigens: lipopolysaccharide (LPS) and capsular polysaccharide (CPS). Adhesion molecules ICAM-1, VCAM-1 and E-selectin (ELAM-1) are induced on the endothelial cells by mediators of inflammation. The aim of this study was to assay the ability of B. thetaiotaomicron surface antigens to induce adhesion molecule expression on the endothelial cells. The influence of LPS and CPS on the expression of adhesion molecules on HMEC-1 cell line was examined in an ELISA test. ELISA was performed with monoclonal mouse anti-human: ICAM-1, VCAM-1 and E-selectin antibodies of the IgG class. B. thetaiotaomicron lipopolysaccharides revealed the ability to induce ICAM-1, VCAM-1 and E-selectin expression on the endothelial cells. Their activities were similar, but lower than the activity of Eschericha coli LPS. ICAM-1 was the most stimulated adhesion molecule. The strongest activation by LPS was achieved at the concentrations of 10.0 and 1.0 micrograms/ml. The ability of capsular polysaccharide to induce the expression of adhesion molecules was considerably weaker.

[Detection of toxin producing strains of Clostridium difficile using rapid diagnostic methods]

Feces of 53 patients from different hospital wards suffering from long term post-antibiotic therapy diarrhea were tested. For direct detection of C. difficile toxin A, in samples TCD (Becton-Dickinson), and C. difficile Toxin A Test (Oxoid) tests were used. Toxin A was detected in 16 samples (29.6% tested). C. difficile strains were isolated from 40% of the fecal samples. Toxin A was detected in 25 Clostridium difficile strains with commercial tests and toxin B was detected using McCoy cell line. Toxin A was not produced by 3 C. difficile strains in vitro, but toxin B was produced by all strains. The polymerase chain reaction (PCR) test showed that all isolated strains possess genes of toxins A and B.

[Drug resistance in nosocomial strains of staphylococci to methicillin]

The aim of the present study was the analysis of drug susceptibility of MRSA and MRCNS strains isolated from patients hospitalized in 14 wards of the State Clinical Hospital No 1 in Warsaw. The strains were identified (ID 32 STAPH), and their susceptibility to antimicrobial agents (ATB STAPH) was determined in ATB system (bioMérieux, France). Four methods were applied to confirm the resistance to methicillin: ATB-plus system, disc-diffusion method (Oxa 1 microgram, Oxoid, U.K.), Crystal MRSA ID (Becton Dickinson-BBL, USA) and agar screen test in TSA medium (Difco, USA) with methicillin (25 mg/l, Sigma, USA). 108 Staphylococcus spp. strains were found in 300 clinical specimens. 56 strains were methicillin-resistant (52%). Among methicillin-resistant strains 13 MRSA, 28 MRSE and 15 of other species were found. All MRSA strains were susceptible to vancomycin, teicoplanin and fusidic acid. MRCNS were susceptible first of all to vancomycin (43/43), minocycline (42/43) and pristinamycin (42/43). On the basis of the obtained results it can be stated that methicillin-resistant staphylococci occur in hospital wards. The greatest number of methicillin-resistant strains was cultured from patients hospitalized in surgery wards (32), methicillin-resistant strains much more frequently occur among coagulase-negative staphylococci, especially in Staphylococcus epidermis. Glycopeptide antibiotics are most active against isolated MRSA strains. The most active therapeutic agent against MRCNS is vancomycin.

Dioctahedral smectite neutralization activity of Clostridium difficile and Bacteroides fragilis toxins in vitro

The neutralization activity of dioctahedral smectite for ten toxigenic Clostridium difficile and eight enterotoxigenic Bacteroides fragilis strains was studied using McCoy and HT 29/C1 cell lines, respectively. Minimalization of the cytopathic effect of C. difficile toxin B on McCoy cell lines by dioctahedral smectite dissolved in PBS was observed. After incubation with dioctahedral smectite the toxic effects of B. fragilis enterotoxins on HT/29C1 (human colon adenocarcinoma cell line) were eliminated. Best neutralization of B. fragilis toxin was achieved using dioctahedral smectite dissolved in BHI.

Immunochemical characterization of Bacteroides vulgatus cell-surface antigens

Capsular polysaccharide (CPS) and lipopolysaccharide (LPS) antigens extracted from three Bacteroides vulgatus strains (serotype specific strain, and two others isolated from normal gut flora and gut of a diabetic patient) were studied. Chemical analysis of CPS and purified LPS antigens was performed. The compositions of sugars, amino acids and fatty acids were shown to be different for each antigen. Rabbit antisera against whole bacterial cells were prepared. All antigens proved to be active in immunoelectrophoresis, SDS-PAGE and immunoblot tests. Several cross reactions in these assays were observed.

[Use of the LAL test for quantitative determination of Bacteroids fragilis endotoxin]

The aim of this study was the evaluation of LAL test with chromogenic substrate usefulness for the quantitative detection of B. fragilis endotoxin and the determination of the amount of endotoxin in culture filtrates of the strains of this species. Also, the trial was undertaken to determine the influence of clindamycin on endotoxin release from B. fragilis rods to the culture medium. Four B. fragilis strains were examined: one nonenterotoxigenic (NTBF) and three enterotoxigenic (ETBF). The growth of cultures was determined and endotoxin liberated to the culture medium during growth of strains was detected. BHI broth and BHI broth with addition of sub inhibitory doses (sub-MIC) of clindamycin were applied. Bacterial cultures were incubated for 48 hours at 37 degrees C. Samples of bacterial cultures were collected after 4, 8, 16, 24 and 48 hours of cultivation, and the optical density was measured. Then the samples were centrifuged, supernatants were filtered through 0.45 micron filters and concentrated three times with 5000 D ultrafilters. Prepared samples were kept frozen at -70 degrees C until used. The amount of endotoxin in samples was determined using quantitative LAL test with chromogenic substrate S-2423. The results of the experiments indicate that LAL test is the useful method for determination of B. fragilis endotoxin concentration. This endotoxin activates the enzymatic system present in Limulus polyphemus amebocyte lysate. Endotoxin is shed spontaneously by B. fragilis rods to the culture medium during growth. Clindamycin at subinhibitory concentrations (sub-MIC) inhibits the growth of cultures of examined strains. The antibiotic caused increase in endotoxin amount in culture medium.

[Comparison of several methods for detection of methicillin resistance in clinical strains of Staphylococcus sp]

108 Staphylococcus spp. strains from 300 clinical specimens from hospitalized patients were isolated. Identification and drug resistance were determined using automated ATB system. 37 S. aureus strains, 44 S. epidermides strains and 27 strains of other coagulase-negative staphylococci were cultured. Sensitivity to methicillin of S. aureus was determined with four methods: ATB system, disc-diffusion (Oxa 1 microgram), Crystal MRSA ID System and agar screen test in TSA medium with methicillin (25 micrograms/ml). 13 S. aureus strains (about 1/3 of strains) were methicillin-resistant (MRSA). Complete conformity of the results was obtained with Crystal MRSA ID, disc-diffusion and agar screen tests. In the case of three S. aureus strains the results of determination in ATB system were not consistent with the results obtained with the use of the methods mentioned above. Susceptibility to methicillin of 71 coagulase-negative strains (CNS) was determined using two methods at first: ATB and disc-diffusion. In the case of 25 methicillin-resistant strains identical results were obtained. For 20 coagulase-negative strains non-conformity with the results of these two methods was observed. As the decisive method, the agar screen test (TSA-MET) was applied. 18 of these 20 CNS strains were categorized as methicillin-resistant. Finally, 43 MRCNS (i.e. 60%) were detected among 71 coagulase-negative strains. The results of methicillin resistance determination of staphylococci in an automated system should be confirmed with a second test such as agar screen, disc-diffusion or Crystal MRSA ID System (in the case of S. aureus).

[Detection of endotoxins and enterotoxins of Bacteroides fragilis in culture media]

Four B. fragilis strains were studied one nonenterotoxigenic (NTBF) and three enterotoxigenic (ETBF). Endotoxin and enterotoxin which are released into the culture medium during the growth of strains were detected. Cultures in BHI broth were incubated for 48 hours at 37 degrees C. After 4, 8, 16, 24 and 48 hours of cultivation, samples of bacterial culture were collected and the optical density was measured. Then the samples were centrifuged, supernatants were filtered through 0.45 micron filters and concentrated three times with 5000 D ultrafilters. Prepared samples were kept frozen at 70 degrees C until use. The presence of endotoxin in samples was revealed by means of immunoelectroprecipitation (IEP) and immunoenzymatic test (dot-ELISA). The assays were performed with antibacterial rabbit immune sera. The activity of enterotoxin was detected on a human colon adenocarcinoma cell line HT 29/C1. The results of the study indicate that endotoxin is released spontaneously by nonenterotoxigenic IPL E 323 strain into the culture medium at the early stages of cultivation. The presence of endotoxin is not demonstrated by means of immunoelectroprecipitation in culture filtrated of ETBF strains. Trace amounts of endotoxin are revealed with dot-ELISA. The activity of enterotoxin is detected after 16 hours of incubation of ETBF strains.

[Microflora of periodontal pockets in advanced periodontitis]

The aim of study was the evaluation of periodontal pockets microflora in patients with advanced periodontitis. From each subject 16-20 samples were taken using paper points. Pooled sample after 60 s. mixing was serially diluted in reduced BHI. For total cell counts and for the isolation of black pigmented anaerobes Brucella agar supplemented with 5% sheep blood, hemin, menadione, with and without Kanamycin-Vancomycin mixture and BM agar plates were used. For isolation of A. actinomycetemcomitans TSBV agar plates were used. Cultures were incubated in anaerobic chamber at 37 degrees C for 7 days and TSBV agar plates in an atmosphere of 95% air-5% CO2 at 37 degrees C for 5 days. Microorganisms were identified by Gram staining, colony morphology, fluorescence in UV-light, haemagglutination of 3% sheep erythrocytes, fermentation of sugars, production of indole, urease (API 20A), specific enzymes (Rapid ID 32A). Twenty seven subjects with clinically recognized periodontitis were examined. Microorganisms important in periodontitis were isolated from periodontal pockets of almost all examined subjects. The number of bacteria obtained from the sample of one patient ranged from 1 x 10(4) CFU/ml to 3,6 x 10(6) CFU/ml. Porphyromonas gingivalis was identified in the samples taken from 17 patients, Prevotella intermedia-19, Actinobacillus actinomycetemcomitans -11, Fusobacterium nucleatum-9, Peptostreptococcus spp.-22.

[Production of enterotoxins by Bacteroids fragilis strains--effect of clindamycin]

Four B. fragilis strains were examined: one nonenterotoxigenic (NTBF) and three producing enterotoxin (ETBF). The growth of cultures was determined and enterotoxin, which is released to the culture medium during growth of strains, was detected. BHI broth and BHI broth with addition of subinhibitory doses (sub-MIC) of clindamycin were applied. Bacterial cultures were incubated at 37 degrees C for 48 hours. After 4, 8, 16, 24, 48 hours of cultivation, samples of bacterial cultures were collected and the optical density was measured. Then the samples were centrifuged, supernatants were filtered through 0.45 micron filters and concentrated three times with 5000 D ultrafilters. Prepared samples were kept frozen at -70 degrees C until used. The titre of enterotoxin in samples was determined on human colon adenocarcinoma cell line HT 29/C1. Neutralization assay was performed with culture filtrates, which were enterotoxin-positive and with rabbit anti-enterotoxin serum. The results of the experiments indicate that enterotoxin is detected after 16 hours of incubation of ETBF strains. Clindamycin at subinhibitory concentrations (sub-MIC) inhibits the growth of B. fragilis cultures. The antibiotic causes also delay and decrease in enterotoxin production by ETBF strains.

Tumor necrosis factor-alpha in response to endotoxin administration in the pregnant guinea pig

OBJECTIVE

Our purpose was to test the hypothesis that an intramuscular endotoxin challenge induces production of tumor necrosis factor-alpha in the pregnant guinea pig and to investigate some of the metabolic effects.

STUDY DESIGN

Twelve randomly selected guinea pigs at 33 days' gestation with a sampling catheter in the carotid artery received an intramuscular injection of a solution of endotoxin isolated from Bacteroides fragilis (n = 6) or of solvent alone (n = 6). Plasma values of tumor necrosis factor-alpha, hematocrit, and 6-keto-prostaglandin F1 alpha were determined before and several hours after injection.

RESULTS

Tumor necrosis factor-alpha was detected in five of six guinea pigs, but it could not be demonstrated in five of six placebo animals. The hematocrit was significantly decreased, and prostaglandin F1 alpha significantly increased 24 to 48 hours after endotoxin injection.

CONCLUSION

In pregnant guinea pigs an intramuscular endotoxin challenge induces the release of tumor necrosis factor-alpha, followed by a reduced hematocrit and an increased prostacyclin concentration. These effects could be involved in the pathogenesis of endotoxin-induced fetal growth retardation.

Detection of enterotoxigenic Bacteroides fragilis (ETBF), among strains isolated between 1976 and 1995 in Poland

Thirty five Bacteroides fragilis strains isolated from different, clinical specimens in 1976-1985 and in 1995, preserved in strains collection of Department of Clinical Bacteriology were studied. The cytotoxicity of 35 bacterial culture supernatants, were tested on the human carcinoma cell line HT29/C1. Two strains proved to be enterotoxigenic. One of those strains was isolated in 1985 from the human, before the existence of enterotoxin producing strain was reported. All 35 strains were metronidazol sensitive showing lack of correlation between enterotoxigenicity and metronidazol resistance.

[Bacterial flora in the digestive tract during diarrhea in infants upon hospital admission and at the end of hospitalization]

The stools of 23 children aged from 14 days to 18 months were analysed (qualitatively and quantitatively) for some genera of bacteria which could be the cause of diarrhea. Feces were collected at the beginning and the end of hospitalisation. The results were evaluated and referred to five age subgroups and duration of hospitalization. The presence of potentially enteropathogenic bacteria was noted in 87 per cent of children in widely varying quantities. In the most numerous group of children the same bacteria were revealed at the beginning and at the end of hospitalization. The microorganisms were most frequently present at the moment of hospitalisation in newborn children. Complete elimination during stay in hospital occurred mainly in the youngest children, who did not acquire these bacteria during their stay in hospital. Colonisation with potentially pathogenic strains in hospital affected mainly children aged 7 to 12 months. EPEC prevailed among the strains isolated in both analyses.

[Occurrence of Bacteroides fragilis strains in full term and post term pregnancies]

Bacteroides fragilis (B.f.) is an aetiological agent of gynecological and obstetrical infections. The aim of this study was to determine occurrence of B.f. in women genital tract. A total number of 118 women in labor between 38 and 43 gestation age and not demonstrating clinical symptoms of infection was examined. B.f. strains were isolated from 9 women (15.9%). More often B.f. strains were isolated from women delivering post-term and staying previously in Pregnancy Pathology Ward. It was observed that infant mean weight on the 3rd day of life was higher in the vagina. The following features of isolates were compared: presence of the capsule and agglutination of sheet erythrocytes. Differences in haemagglutination and susceptibility to antibiotics were observed.

[Study of the thermoresistance of Clostridium difficile spores]

Thermoresistance of C. difficile spores was investigated. C. difficile strains were isolated from different sources. As control, toxigenic VPI 10463 and nontoxigenic NIH BRIGGS 8050 C. difficile strains were used. The inhibition of growth majority of C. difficile after heating at 85 degrees C was shown. No correlation between thermoresistance of C. difficile spores, toxigenicity and source of the strains was observed.

[Fecal flora in infants at the beginning and the end of hospitalization]

The feces of 52 children without diarrhea, aged from 5 days to 22 months, treated in the Department for various causes was investigated for the presence of that might be the cause of infectious diarrhea. Samples were taken at the beginning and the end of hospitalization. The results were analyzed with reference to 5 age subgroups (1 month, 2-3 months, 4-6 months, 7-12 months, 12-22 months) and duration of hospitalization (3-42 days). The presence of potentially pathogenic bacteria in the feces was found in 87% of children without diarrhea, especially at the beginning of hospitalization, which suggests the possible existence of a "transient carrier state". Because of the immaturity of a number of intra-organism mechanisms, the presence of pathogenic bacteria in the alimentary tract in the youngest children, may be a potential danger of developing serious, even generalized disease processes and may constitute an important source of nosocomial infections.

Detection of Bacteroides fragilis endotoxin in amniotic fluid by counterimmunoelectrophoresis

The ability of counter immunoelectrophoresis (CIE) to detect Bacteroides fragilis endotoxin in amniotic fluid in small concentrations was evaluated. A method was developed which, in combination with ultrafiltration, permits detection of B. fragilis endotoxin in amniotic fluid in a concentration of 40 ng/ml or more. The sensitivity threshold was reduced to 2 ng/ml by using a highly reactive IgG-fraction isolated from rabbit anti-B. fragilis IPL E 323 antiserum.

Clostridium difficile in a department of surgery

The colonization and transmission of Clostridium difficile strains was investigated at the Department of Surgery. Anaerobes were isolated from fecal samples of 27 patients among 308 investigated (mean age: 59.5 years). The majority of them (22 out of 27 patients) received anti-microbial agents prior to investigation for Clostridium difficile. Eighteen of them had undergone various surgical procedures including laparotomies. Only four Clostridium difficile positive patients had diarrhea, but pseudomembranes were not observed endoscopically. The highest colonization rate of C. difficile (20/27) was found to occur in autumn. All 54 samples from medical personnel were C. difficile free. C. difficile was isolated in 7% of samples taken from hospital environment. Toxigenicity of Clostridium difficile strains isolated from fecal samples taken from patients and from environment was 78% and 80%, respectively, as determined by cytotoxicity tissue assay, or 70% and 20%, respectively, in the latex agglutination test.

Endotoxin-induced fetal growth retardation in the pregnant guinea pig

OBJECTIVES

Our purpose was to test the hypothesis that bacterial endotoxin may reduce fetal growth and to assess some of the pathophysiologic mechanisms of such an effect.

STUDY DESIGN

Two randomly selected groups of nine guinea pigs at 30 days' gestation were treated with a solution of endotoxin isolated from Bacteroides fragilis or with solvent alone. Antibody titers, glucose, triglycerides, and 6-keto-prostaglandin F1 alpha were determined in maternal or fetal blood samples. Fetal weight was determined at 61 days' gestation.

RESULTS

Endotoxin-treated guinea pigs showed positive antiendotoxin antibody titers, reduced weight gain, and significantly higher serum levels of triglycerides and 6-keto-prostaglandin F1 alpha, but not of glucose, than did sham-treated controls. Fetuses of endotoxin-treated animals had significantly lower birth weights and serum glucose concentrations and significantly higher triglyceride levels than did control fetuses.

CONCLUSIONS

Bacteroides fragilis endotoxin causes fetal growth retardation in the pregnant guinea pig, which may be due to alterations in carbohydrate and fat metabolism mediated by cytokine action.

[Comparison of 2 methods of qualitative bacteriological urinalysis]

Two techniques of the quantitative bacteriological urinalysis were compared. Hundred seventy eight samples of the urine were analysed with routine technique and paper strip test "Mast Bacteriuritest". Hundred percent conformity of both techniques was obtained in case of insignificant bacteriuria. In case of significant bacteriuria the results differed: paper tests were negative in 10% of cases. Significant bacteriuria was diagnosed in the samples in which Gould's test was positive with routine technique in 22% and with paper test in 18% of the analysed samples. It seems that paper test is valuable quantitative technique of the urinalysis because of its simplicity and low cost. It should be used, however, for the detection of the significant bacteriuria.

The effects of deoxycholate and sodium dodecyl sulphate on the serological reactivity of antigens isolated from six Bacteroides reference strains

The detergents sodium dodecyl sulphate (SDS) and sodium deoxycholate (NaD) are frequently used as solvents for macromolecular polysaccharide complexes in immunochemical and serological techniques. The influence of the disaggregating surfactants on the serological reactivity of endotoxins isolated from six serotype specific reference strains of the Bacteroides fragilis group was investigated by comparing haemagglutinating and precipitating reactivities of antigen solutions in phosphate buffered saline (PBS), NaD and SDS. All antigens were phenol/water extracted endotoxins. Solutions of antigens isolated from serotypes A, B, C and D in PBS exhibited mainly serotype specificity and a few well known low-titer cross reactions; solutions in NaD showed additional cross reactivity, which was enhanced by solubilization of the antigens in SDS. In immunoelectrophoresis endotoxins isolated from serotypes A and C and dissolved in NaD or SDS showed additional precipitation lines compared to solutions of the same antigens in PBS. These changes in the serological reactivity are of relevance for investigations where the serological specificity of antigens is in question.

Immune response to endotoxin isolated from Bacteroides fragilis in the pregnant guinea pig

The humoral immune response to endotoxin isolated from Bacteroides fragilis was analyzed in the pregnant guinea pig by means of passive hemagglutination, passive hemolysis, a modified Coombs test, and by crossed immunoelectrophoresis. Pregnant animals were immunized with endotoxin on day 30 of gestation, and antibodies were determined on day 61 in maternal and fetal sera, and in amniotic fluid. The IgG and IgM responses in maternal sera were of the same magnitude as in sera of nonpregnant animals. Fetal sera contained IgG and sometimes IgM, and a higher percentage of incomplete antibodies against endotoxin than maternal sera. Low-titer anti-endotoxin antibodies, partially sensitive to dithiothreitol, were found in amniotic fluid. A statistically significant reduction in the growth of fetuses from endotoxin-immunized females was observed.

Detection of 2-keto-3-deoxyoctonate in endotoxins isolated from six reference strains of the Bacteroides fragilis group

1. Endotoxins isolated from six serotype specific reference strains of the Bacteroides fragilis group were dephosphorylated by treatment with aqueous 50% hydrofluoric acid. 2. Mild acidic hydrolysis of the dephosphorylated endotoxins released 2-keto-3-deoxyaldonic acid, the presence of which was demonstrated by the colorimetric thiobarbituric acid assay (TBA). 3. Thin layer chromatography of the dephosphorylated lipopolysaccharide of B. fragilis IPL E 323 (serotype E2), after acidic hydrolysis, revealed a TBA-positive substance with the same Rf-value as authentical 2-keto-3-deoxyoctolusonic acid (KDO). 4. Quantification of 2-keto-3-deoxyoctonate-in the lipopolysaccharide of B. fragilis IPL E 323 by means of the TBA resulted in a KDO content of 15 nM mg-1 lipopolysaccharide.

Immunochemical investigations of antigens isolated from Bacteroides ovatus strain ATCC 8483

A saline extract (SE) and a phenol/water extract (WL) were prepared from Bacteroides ovatus strain ATCC 8483. A fraction CS was isolated from the culture supernatant. WL was further split by ultracentrifugation into lipopolysaccharide (LPS) and supernatant (L1). Fractions SE, WL, LPS and L1 reacted serologically with homologous antiserum but did not cross-react with antisera against heterologous Bacteroides serotypes. Fraction CS was inactive in haemagglutination, haemagglutination inhibition and immunoelectrophoresis tests. SE, WL, LPS and L1 proved to be serologically heterogeneous. A distinct serological specificity for SE was demonstrated. The serological reactivity in SE and WL was not altered after treatment with proteolytic enzymes yet completely destroyed in WL and partially in SE by sodium metaperiodate. SE, WL, LPS and L1 contained the sugar components rhamnose, fucose, ribose, mannose, galactose, glucose and glucosamine in different molar ratios for each fraction. Galactosamine was found in WL and LPS, uronic acid in WL and L1. Two unidentified aminohexoses were detected in WL, one of which was also detectable in L1 and SE. 2-Keto-3-deoxyaldonic acid was demonstrated in LPS and L1 after strong acid hydrolysis.

Immunochemical and biological studies of antigens isolated from a strain of Bacteroides fragilis

Phenol/water-extracted lipopolysaccharide and a fraction of HM, extracted with acetate buffer pH 2.0, from Bacteroides fragilis strain 62/73 are antigenically different as shown by immunodiffusion, passive haemagglutination, haemagglutination inhibition and preliminary chemical investigations. Biological activity, assessed with the local Shwartzmann reaction, was demonstrated for the lipopolysaccharide whereas antigen HM was almost inactive in this test. HM is immunogenic in rabbits. Antibodies against HM were detected in seven out of ten sera of healthy humans.