Anaerobic yeast killer systems

The influence of anaerobic conditions on the expression of the killer phenomenon of several yeast isolates belonging to recognized killer systems coded by different genetic determinants (Pichia spp., Kluyveromyces lactis, Saccharomyces cerevisiae) was studied. Anaerobiosis influenced the activity of killer toxins from some individual isolates of the genera Pichia and Saccharomyces on sensitive strains of P. anomala, K. lactis and Candida albicans. However, no influence was detectable on a S. cerevisiae sensitive isolate. Thus, anaerobic conditions seem to interfere more with the metabolic process of sensitive strains than with toxin production by killer yeasts.The selection of a panel of killer yeasts, able to display their activity against reference sensitive yeast isolates under anaerobic conditions in a medium that favored the growth of anaerobes, allowed the use of the killer system to type Bacteroides fragilis isolates for epidemiological purposes.     

Purification and properties of neuraminidase from the culture medium of Bacteroides loescheii

Neuraminidase was purified from the culture medium of Bacteroides loescheii ATCC 15930 by ultrafiltration followed by a DEAE-Sephacel anion exchange chromatography, fast-protein liquid chromatography using Mono P column and high-performance liquid chromatography using a Shim-pack Diol-300 column. The molecular weight of the purified enzyme was measured to be approximately 87 kDa and the optimal pH was at 4.8. Although the enzyme was able to hydrolyze the substrates with alpha,2-3, alpha,2-6, and alpha,2-8 linkages of N-acetylneuraminic acid, the rate of hydrolysis of N-acetylneuraminosyl-alpha,2-3-lactose was greater than that of the alpha,2-6-isomer.     

SDS-PAGE analysis of protein and lipopolysaccharide of extracellular vesicules and Sarkosyl-insoluble membranes from Bacteroides gingivalis

We have compared outer membranes (OM) of Bacteroides gingivalis ATCC 33277 isolated by the following 3 techniques: 1) high speed centrifugation after mechanical cell shearing; 2) sonication of the bacteria, followed by solubilization of the cytoplasmic membrane with N-Laurylsarconsinate (Sarkosyl), after which the Sarkosyl-insoluble membranes were recovered by centrifugation; 3) ammonium sulfate precipitation of extracellular vesicules from culture supernatant, followed by centrifugation and dialysis. Electron microscopy showed that the 3 preparations consisted of closed vesicules. Analysis by SDS-PAGE revealed that all 3 contained up to 28 polypeptides, most of which were common to each extract. The extracellular vesicules and Sarkosyl-insoluble preparation yielded similar protein patterns, although quantitative differences were observed. The sheared-cell preparation contained 8 additional proteins. The level of contamination of OM material by peptidoglycan and cytosol components was 1.8% in the sheared-cell preparation, and was null or lower than 0.8% in the other preparations. All 3 preparations showed the presence of LPS with a multiple banding pattern typical of smooth LPS. The sheared-cell preparation had a slightly lower LPS content than the other 2 preparations. Since extracellular vesicules are naturally released during bacterial growth, and are relatively simple to obtain, such native entities seem an appropriate source of OM components for use in studying the immunobiology of B. gingivalis surface antigens.     

Periodontal bone level and gingival proteinase activity in gnotobiotic rats immunized with Bacteroides gingivalis

Bacteroides gingivalis is associated with various forms of periodontal disease. To assess the role of the immune response in modulating B. gingivalis-associated periodontal disease, the effect of immunization of B. gingivalis-induced periodontal bone loss was evaluated in gnotobiotic rats. Male Sprague-Dawley rats immunized with various doses of whole cells or sham-immunized with incomplete Freund's adjuvant were monoinfected with B. gingivalis in carboxymethylcellulose by gavage. Two additional groups served as either sham-immunized or untreated germ-free controls. Forty-two days after infection, all rats were killed, periodontal bone level was assessed morphometrically and radiographically, and gingival proteinase (mammalian collagenase and acid cathepsin) activity was assessed biochemically. B. gingivalis was present in oral samples from all monoinfected rats, and no contaminating bacteria were detected in any oral or fecal sample. Animals immunized with B. gingivalis cells had elevated serum and saliva antibodies to whole cells and partially purified fimbriae from B. gingivalis. Infected sham-immunized rats had significantly more periodontal bone loss than noninfected controls, whereas the periodontal bone level in infected rats immunized with 10(10) B. gingivalis cells was similar to that of the noninfected controls. The activities of gingival collagenase and cathepsin B and L were high in sham-immunized infected rats and low in all other animal groups. In conclusion, it is possible to reduce B. gingivalis-induced periodontal tissue loss in gnotobiotic rats by immunization.     

Crystal Containing Membrane Bound Intracellular Inclusion Bodies in the Epithelium of Experimentally Infected Sinus Mucosa

The sinus mucosa of 16 rabbits was experimentally infected with Bacteroides fragilis. This paper describes and discusses large inclusion bodies, which were found in abundance by light and electron microscopy inside ciliated cells of the sinus epithelium in 3 of the studied animals. The spindle-shaped inclusions were located in the apical portion of the cytoplasm. They were bound by a trilaminar membrane with several coils to the interior as well as to the exterior. The interior of an inclusion body consisted to a large extent of electron-lucent, floccular substance, but fibrogranular aggregates and rod-shaped crystals with a line periodicity center-to-center of about 15 nm were also conspicuous. These peculiar formations may be constituted by abnormally stored material from defective synthesis of cilia.     

Anaerobic bacteremia in a cancer center

Seventy-five episodes of clinically relevant anaerobic bacterial bacteremia observed in cancer patients were reviewed. Gastrointestinal (22.7%), hematological (22.7%) and female genital tract (18.6%) cancers were the most common underlying malignant diseases. Among 84 strains of strict anaerobic bacteria recovered in the 75 patients, gram-negative rods were isolated in 49 patients (58.3%), gram-positive rods in 29 patients (34.5%) and gram-positive cocci in 6 patients (8%). Bacteroides spp. and Clostridium spp. were the most frequent pathogens (85.7%). Twenty-one episodes of bacteremia were polymicrobial, aerobic gram-positive cocci being the most frequently associated pathogens. When identified, the primary sites were the gastrointestinal tract (40%), the female genital tract (17.3%), skin and soft tissue (14.6%), the oropharynx (12%) and the lower respiratory tract (6.7%). The source remained unknown in 7 cases (9.3%). The overall survival (evaluated 10 days after the occurrence of bacteremia) was 82.5%. There was no difference in mortality between patients with monomicrobial and polymicrobial bacteremia. Pulmonary complications were more frequent in patients with fatal outcome in comparison to patients who survived. The mortality rate of the patients adequately treated was 10.3% compared to 41% for the patients not treated or treated inadequately (P=0.016, X₂).     

Comparative in vitro activity of ceftaroline,ceftaroline-avibactam,and other antimicrobial agents against aerobic and anaerobic bacteria cultured from infected diabetic foot wounds

Foot infections are the most common infectious complication of diabetes. Moderate to severe diabetic foot infections (DFI) are typically polymicrobial with both aerobic and anaerobic organisms. The role of MRSA in these wounds has become an increasing concern. To determine if the addition of avibactam, a novel non-beta-lactam beta-lactamase inhibitor, to ceftaroline would be more active than ceftaroline alone, we tested 316 aerobic pathogens and 154 anaerobic recovered from patients with moderate to severe DFI, and compared ceftaroline with and without avibactam to other agents. Testing on aerobes was done by broth microdilution and by agar dilution for anaerobes, according to CLSI M11-A8, and M7-A8 standards. Ceftaroline-avibactam MIC₉₀ for all Staphylococcus spp. including MRSA was 0.5 μg/mL, and for enterococci was 1 μg/mL. The MIC₉₀s for enteric Gram-negative rods was 0.125 μg/mL. The addition of avibactam to ceftaroline reduced the ceftaroline MICs for 2 strains of resistant Enterobacter spp. and for 1 strain of Morganella. Against anaerobic Gram-positive cocci ceftaroline-avibactam had an MIC₉₀ 0.125 μg/mL and for clostridia 1 μg/mL. Avibactam improved ceftaroline’s MIC₉₀s for Bacteroides fragilis from >32 to 2 μg/mL and for Prevotella spp. from >32 to 1 μg/mL. Ceftaroline alone demonstrates excellent in vitro activity against most of the aerobes found in moderate to severe DFI. The addition of avibactam provides an increased spectrum of activity including the beta-lactamase producing Prevotella, Bacteroides fragilis and ceftaroline resistant gram-negative enteric organisms.     

Sequential Changes in Luminal Microflora and Mucosal Cytokine Expression during Developing of Colitis in HLA-B27/β 2 -Microglobulin Transgenic Rats

Background: Transgenic rats expressing HLA-B27 and human β 2 -microglobulin (HLA-B27 rats) spontaneously develop chronic colitis resembling human inflammatory bowel disease. We investigated the sequential changes in the luminal bacterial flora and mucosal cytokine mRNA expression in this model. Methods: HLA-B27 rats were maintained in a specific pathogen-free environment, and luminal microflora was evaluated by standard bacterial culture technique. The expression of mucosal cytokine mRNA was analysed by RT-PCR methods. Results: Clinical symptoms of colitis appeared at 8 weeks of age. The total number of obligate anaerobes was higher than those of facultative anaerobes during the experimental period. At 6 weeks of age, the colonization of Bacteroides spp., Bifidobacterium spp. and Lactobacillus spp. was already detectable at high concentrations, whereas Clostridium spp. and Eubacterium spp. were not detected. The expression of proinflammatory cytokines (IL-1 β , IL-8 and TNF- α ) appeared at 8 weeks of age, and these were detectable until 17 weeks. A similar pattern was observed in the expression of Th1 cytokines (IL-2, IL-12 and IFN- &#110 ). On the other hand, the expression of Th2 cytokines (IL-4, IL-10 and TGF- β ) was weak. IL-4 mRNA expression was weakly detectable only at 6 and 8 weeks of age. The expression of IL-10 and TGF- β mRNA was scarcely detectable throughout the experimental period. Conclusion: The development of colitis may be mediated by both the predominant expression of Th1 cytokines and the weakness of Th2 cytokine expression in the mucosa. The colonization of anaerobic bacteria, especially Bacteroides spp., may be initiating and promoting these cytokine responses.     

非同位素标记脆弱类杆菌DNA探针的研究

为探索应用分子生物学技术检测厌氧菌的方法，选择脆弱类村抽提其染色体ＤＮＡ，用生物素和地高辛配基标记制备ＤＮＡ探针，检测厌氧和需氧菌９４株，临床标本４５份，并和＾３２Ｐ标记探针及培养生化鉴定比较，该探针可检出临床上常见的类杆菌属细菌与其它细菌无交叉反应，结果：地高辛配基标记探针的灵敏度（１０ｐｇＤＮＡ和１０＾３ＣＦＵ／ｍｌ）接近＾３２Ｐ标记探针的灵敏度（１ｐｇＤＮＡ和１０＾３ＣＦＵ／ｍｌ）。地高辛配     

Septic arthritis due to bacteroides fragilis after pilonidal sinus resection in a patient with rheumatoid arthritis

Summary Bacteroides fragilis is a rare cause of septic arthritis. Most patients with B.fragilis septic arthritis have a chronic joint disease, particularly rheumatoid arthritis, and sources of infection are lesions of the gastrointestinal tract and the skin. We report a 69-year-old male, who developed B.fragilis septic arthritis after pilonidal sinus resection. High level of suspicion of development B.fragilis septic arthritis must be present in patients with chronic joint disease in whom gastrointestinal or skin surgery was previously performed.