Bacteroides Organisms Research Articles

Role of Microbiota in Strengthening Ocular Mucosal Barrier Function Through Secretory IgA.

PurposeThe purpose of this study was to evaluate mechanisms controlling secretory IgA (SIgA) production, thereby ensuring maintenance of ocular surface health.MethodsTo determine whether the presence of specific gut commensal species regulates SIgA levels and IgA transcripts in the eye-associated lymphoid tissues (EALT), specific-pathogen-free (SPF) Swiss Webster (SW) mice were treated with antibiotic cocktails, germ-free (GF) SW mice were reconstituted with diverse commensal gut microbiota, or monocolonized with gut-specific commensals. Proteomic profiling and quantitative real-time polymerase chain reaction (qRT-PCR) were used to quantify SIgA and IgA levels. 16S rDNA sequencing was carried out to characterize commensal microbiota.ResultsCommensal presence regulated ocular surface SIgA levels and mRNA IgA transcripts in EALT. Oral antibiotic cocktail intake significantly reduced gut commensal presence, while maintaining ocular surface commensal levels reduced SIgA and IgA transcripts in EALT. Analysis of gut microbial communities revealed that SPF SW mice carried abundant Bacteroides organisms when compared to SPF C57BL6/N mice, with B. acidifaciens being the most prominent species in SPF SW mice. Monocolonization of GF SW mice with B. acidifaciens, a strict gut anaerobe, resulted in significant increase of IgA transcripts in the EALT, implying generation of B-cell memory.ConclusionsThese data illustrated a “gut-eye” axis of immune regulation. Exposure of the host to gut commensal species may serve as a priming signal to generate B-cell repertoires at sites different from the gut, such as EALT, thereby ensuring broad protection.

Nosocomial abscess. Results of an eight-year prospective study of 32,284 operations.

This article details the results of 114 abscesses found after 32,284 operations during a 30-day prospective infection surveillance. Abscesses occurred more often after gastric/esophageal (3.6%), colonic/appendiceal (2.8%), and pancreatic/biliary (1.5%) operations. Abscesses were intra-abdominal (58%), pelvic/perineal (31%), and retroperitoneal (3%). The most common pathogens were Escherichia coli, enterococci, and Bacteroides organisms. Abscess symptoms appeared 10 +/- 6 days (mean +/- SEM) after surgery and were drained 8 +/- 8 days after onset of symptoms. Hospital stay from onset of symptoms to discharge was four times greater than that for wound infection. Twenty-seven patients (28%) died. Mortality was increased in patients older than 50 years and in those with renal failure or multiple abscesses. Nosocomial abscesses had a greater morbidity than would infection. Excessive expense and high mortality warrant infection surveillance for both wound infection and ongoing nosocomial abscesses.

Treatment of spontaneous bacterial empyema thoracis

The need for decortication to cure primary bacterial (nontuberculous) empyema was evaluated in 112 consecutive patients. Twenty-eight patients (25%) were cured by thoracentesis alone. Intercostal chest tube drainage was required in 43 (39%) and decortication in 41 (36%). Although hospital stay was shortened by 5 days for those who had decortication, the difference was statistically insignificant. Penicillin failed to eradicate infection in nine of 17 patients, four of whom had Bacteroides organisms. There were no therapeutic failures among 46 patients treated with clindamycin and gentamicin. We conclude that conservative therapy, such as thoracentesis, antibiotics directed against anaerobic bacteria, and intercostal tube drainage (thoracostomy), was adequate to achieve clinical and physiologic resolution in about two thirds of all patients with primary bacterial empyema. The remaining one third required decortication. Rib resection and Eloesser flap procedures seem to be unnecessary in the treatment of primary bacterial empyema.

Organisms isolated from severe odontogenic soft tissue infections: Their sensitivities to cefotetan and seven other antibiotics, and implications for therapy and prophylaxis

Cefotetan is a new cephamycin antibiotic characterised by excellent B-lactamase stability and anti-anaerobe activity, coupled with a long half life of 3–4 h which permits twice daily dosage. A clinical trial of cefotetan in the treatment of severe oro-facial infections is presented, together with a detailed analysis of the causative organisms and their sensitivities to eight antibiotics. 50 50 patients achieved clinical cure with a treatment regime comprising cefotetan therapy and incision and drainage, with patients being transferred to oral cephradine for the final phase of therapy. Side effects were minimal and there were no instances of relapse. Significant resistance among α-haemolytic streptococci and bacteroides organisms to penicillin was observed. The streptococci were resistant due to mechanisms other than β-lactamase production. In the light of these findings and the reports of other workers it is suggested that penicillin V may no longer be the most appropriate drug for endocarditis prophylaxis, despite the most recent recommendations of the American Heart Association. Furthermore, if penicillin V is used for this purpose, a penicillin free interval of 6–8 weeks may be inadequate before this drug is used. Cefotetan is not suitable for prophylaxis against endocarditis.

Distribution and effects of a defined six-member murine-derived microflora in gnotobiotic gerbils.

The gnotobiotic gerbil was selected as a model with which to study the effects of colonization with a defined microflora on organ morphology, histology, and selected blood biochemical parameters. Gerbils were maintained germfree for 13 months but failed to reproduce, presumably because of the enlarged cecum. A colony of gnotobiotic gerbils that was associated with a bacterial flora consisting of Lactobacillus brevis, Streptococcus faecalis, Staphylococcus epidermidis, Bacteroides vulgatus, Enterobacter aerogenes, and a Fusobacterium sp. was established. These gnotobiotic gerbils had smaller ceca than germfree gerbils and proved capable of reproduction. Except for the presence of large numbers of Bacteroides organisms in the stomach and greater numbers of S. epidermidis in gnotobiotic gerbils, the number and location of gastrointestinal bacteria were similar in conventional and gnotobiotic gerbils. Bacteroides sp. was the second most predominant microorganism present in gnotobiotic gerbils, whereas clostridia were reported to be the second most predominant microorganism in conventional gerbils. Microscopic examination of direct-impression smears indicated that fusobacteria were present on mucosal surfaces. Intestines of gnotobiotic gerbils weighed twice as much as the intestines of conventional gerbils. Intestinal tissue water weight values from conventional and gnotobiotic gerbils were similar. Histological examination of gerbil intestinal tissue revealed no cellular hypertrophy and no evidence of inflammation in gnotobiotic gerbil intestines. Spleens of gnotobiotic gerbils showed no germinal center stimulation. Statistical differences in total serum glucose, serum protein, and hematocrit levels were found between conventional and gnotobiotic gerbils.

In vitro susceptibility of Gardnerella vaginalis and Bacteroides organisms, associated with nonspecific vaginitis, to sulfonamide preparations.

Recent reports suggest that anaerobic Bacteroides organisms are frequently found with Gardnerella vaginalis in nonspecific vaginitis. Specimens taken from 96 women with vaginal discharge were tested simultaneously for these organisms. G. vaginalis was found in 73% of the specimens, Bacteroides was found in 53%, and both organisms were found in 47%. Sulfonamides have been widely used in the successful treatment of vaginitis. Paradoxically, G. vaginalis is reported to be resistant, and it has been suggested that it could be the vehicle of the drugs which effects the cure. Little is known of the susceptibility of vaginal anaerobes to the sulfonamides. G. vaginalis and Bacteroides isolates were therefore tested in vitro against the individual excipients of sulfonamide tablets, and minimal inhibitory concentration tests were also performed against the three active drugs. The excipients had no effect on G. vaginalis, but Bacteroides strains were susceptible to the urea component. All strains of both organisms were susceptible to at least two of the three sulfonamides at high concentrations.

Detection of species-specific and cross-reactive cell-surface antigens of Bacteroides species by an indirect enzyme-linked immunosorbent assay.

EDTA-released outer-membrane antigen complexes were prepared from 172 laboratory and reference strains and 43 fresh clinical or faecal isolates representing 20 species or subspecies of Bacteroides, together with 13 species of other genera. These antigens were titrated against antisera to whole, live cells of 21 species or subspecies of Bacteroidaceae in an indirect enzyme-linked immunosorbent assay (ELISA). The presence of species-specific antigens was investigated and cross reactions between species were noted. Results showed that a high proportion of the species possess species-specific antigens with little significant cross reactivity. We believe that the ELISA system described here detects antigens that represent the whole cell surface of bacteroides organisms. We have exploited the sensitivity of the system and its quantitative potential to define approaches for those wishing to use serological approaches for either the identification of Bacteroides species or for the titration of serum antibodies in patients with a possible bacteroides infection.

Anaerobic bacteremia in children.

Twenty-nine anaerobic isolates were recovered from 28 pediatric patients with anaerobic bacteremia: 14 Bacteroides sp (11 in the B fragilis group); four anaerobic Gram-positive cocci; four Clostridium sp; four Propionibacterium acnes; and three Fusobacterium sp. No aerobic bacteria were isolated from these patients. The gastrointestinal tract was the possible portal of entry in 13 instances, eight of which were due to Bacteroides organisms, four to Clostridium sp, and one to F nucleatum. The ear, sinus, and oropharynx were probable portals of entry in seven instances, four of which were due to Peptococcus sp and two to Fusobacterium sp. Five patients (18%) died; four had bacteremia caused by B fragilis group, and one had bacteremia caused by P acnes. The average duration of antimicrobial therapy was 20 days (range, seven to 72 days). The early recognition and rapid institution of appropriate antimicrobial and surgical therapy are of utmost importance in improving the outcome of these patients.

Bacteroides meningitis successfully treated with metronidazole

Bacteriodes meningitis without associated cerebral abscess occurred in an elderly man who had a long history of chronic otitis media. Anaerobic cultures of the cerebrospinal fluid revealed bacteroides organisms. Sensitivity testing showed them to be resistant to penicillin and chloramphenicol but sensitive to metronidazole. Appropriate therapy with this agent eradicated the causative organisms and produced rapid clinical improvement.

Bacterial flora of patients with prematurely ruptured membranes.

Twenty consecutive patients with premature rupture of the membranes were studied to determine the vaginal, endocervical, and neonatal bacteriologic flora. Patients who had membranes ruptured for more than 12 hours had more anaerobic species isolated from vaginal plus endocervical or endocervical cultures alone than did those patients with membranes ruptured for less than 12 hours. Overall, aerobic organisms were more frequently isolated than anaerobic organisms, but the majority of cultures were of a mixed flora. Streptococci, corynebacteria, and Bacteroides organisms were the most frequently isolated organisms from all sites cultured. Lactobacilli were isolated in only 45% of endocervical and vaginal cultures, and Enterobacteriaceae were infrequently encountered. This study indicates that there is a change toward a preponderance of anaerobic species in the birth canal when membranes are ruptured for more than 12 hours, and that this change is detectable before delivery.

Treatment of Anaerobic Pulmonary Infections: Carbenicillin Compared to Clindamycin and Gentamicin

Twenty-three patients with anaerobic infections of the lung were treated with either two antibiotics, clindamycin and gentamicin (11 patients) or with a single antibiotic, carbenicillin (12 patients). Cultures were obtained prior to therapy, either by transtracheal needle aspiration (17 patients) or thoracocentesis (six patients). Anaerobic bacteria were found in all. Fifteen patients had aerobic and facultative bacteria in addition. The anerobic isolates were peptostreptococci (12), peptococci (12), Bacteroides organisms (eight), clostridia (three), actinomycetes (two), eubacteria (one), and fusobacteria (one). Aerobes included streptococci (nine), enterococci (seven), Neisseria organisms (two), Klebsiella organisms (one), Citrobacter organisms (one), Pseudomonas organisms (one), Mycobacterium tuberculosis (two), and Nocardia (one). The two patients with pulmonary tuberculosis with anaerobic and superinfection received antituberculosis chemotherapy in addition. Therapeutic response was considered excellent in both groups. This suggests that carbenicillin may be used as a single antibiotic in the treatment of anaerobic and mixed infections of the lung.

Bacteroides bacillemia. Sepsis for surgeons.

Bacteroides species are anaerobic, aero-intolerant, nonsporeforming, nonmotile, gram-negative bacilli that colonize the oropharynx, female genital tract, and large bowel, comprising 95% of the colonic bacterial population and 20% of the dry weight of stool. Bacteriologic identification of Bacteroides organisms is frequently difficult because they are fastidious, sometimes slow-growing, and often resemble Escherichia coli and other gram-negative bacilli morphologically. Specimens infected by Bacteroides organisms may contain many gram-negative rods on gram stain but show no growth on culture if not inoculated promptly into anaerobic media. Infections are often mixed and sometimes fail to yield Bacteroides organisms because of overgrowth by less fastidious bacteria. Commonly, the clinician first recognizes Bacteroides infection in his patient when the laboratory reports blood cultures positive. Accumulating experience suggests that the apparent incidence of bacillemia due to Bacteroides organisms is rising. In 1971 in the Mayo Clinic, Bacteroides was the second most common gramnegative bacillus isolated from

Response of endometrial stromal sarcoma to cyclophosphamide

Endometrial stromal sarcomas represent 0.2 per cent or less of genital tract malignancies. Occasional responses to irradiation have been reported, but no cases responsive to chemotherapy have been reported. A 54-year-old woman was hospitalized for 8 weeks following a total hysterectomy for endometrial stromal sarcoma. On admission extensive metastatic disease was noted and cyclophosphamide, an alkylating agent, was given intravenously with dramatic reduction in the size of the tumor. Secondary renal insufficiency and septicemias due to Bacteroides organisms were successfully treated. Subsequent therapy with oral cyclophosphamide resulted in disappearance of the tumor. Seven months after initial chemotherapy an appendectomy was performed for acute suppurative appendicitis, and at that time there was no evidence of malignant disease. In view of the response obtained with cyclophosphamide further therapeutic trials in such patients are warranted.

Brain Abscess Caused by Bacteroides Infection

DESPITE the fact that Bacteroides organisms have been observed in various human infections since the turn of the century, their importance as pathogens of the central nervous system has only recently been recognized. Bacteroides organisms are strictly anaerobic, nonspore-forming, gramnegative bacilli, which occur most abundantly in the nasopharynx and in the female genital and gastrointestinal tracts; they are believed more numerous than Escherichia coli in the latter region. This genus occurs frequently in mixed colonies with anaerobic and microaerophilic streptococci and is difficult to isolate. 1 Early identification of Bacteroides bacilli is of considerable importance since treatment with newer antibiotics and appropriate surgery have proved quite effective. 1-5 It is the purpose of this report to describe a case of Bacteroides brain abscess and to review some diagnostic, microbiological, and therapeutic problems unique to this infection. Report of a Case A 46-year-old white female patient was admitted to the