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Bacteroides fragilis infection of a juxtapancreatic benign cystic retroperitoneal teratoma in a 28 year old Chinese male is reported. Preliminary drainage was followed by excision. The radiological and pathological findings of this rare tumour are reported with emphasis on the differential diagnosis which includes inflammatory and neoplastic pancreatic cysts.
Metronidazole was found to be active against Bacteroides fragilis strains isolated from human lesions. The minimal inhibitory concentrations (MIC) were from 0.16 to 2.5 mug/ml and the minimal bactericidal concentrations (MBC) were from 0.16 to 2.5 mug/ml; usually the MIC and MBC figures were equivalent. These levels are easily attainable in the serum following normal therapeutic doses. The drug is not toxic and side effects are rare and it would therefore seem highly suitable for treating Bacteroides infections and also may be considered prophylactically in certain situations that are described.
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A bite wound led to necrotizing fasciitis in the temporal space, the lateral pharyngeal space and the carotid sheath, indicative of a Streptococcus and Bacteroides infection, and was successfully treated with repeated incisions, radical debridement and antibiotic therapy.
Surgical infections are almost always polymicrobial, yet the critical importance of bacterial mixtures in these infections has received relatively little attention. The convincing data on the prevalence of mixed infections in surgery are reviewed. Both clinical and experimental evidence indicate that true synergy between certain aerobes and anaerobes may exist. Of the possible mechanisms of synergy, the most important seems to be the ability of anaerobes, their metabolic products, or their capsules to inhibit phagocytosis of aerobes by leukocytes. Other mechanisms of importance in special microbial combinations include provision of essential nutrients such as vitamin K, succinate, and various growth factors by one microbe to the other; alteration of local environment, including reduction of the oxygen tension and lowering of redox potential; and the provision of substances toxic to the host that permit species of bacteria to flourish concurrently. Further study of these interactions will shed light on the causes and correction of treatment failure.
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Overall mortality for 142 patients with Bacteroides bacteremia encountered in the four hospitals of one metropolitan area between 1977 and 1982 was 41%. Only 43% of deaths of these patients, however, were attributed directly to Bacteroides infection according to the criteria used in this study. Deaths of patients with Bacteroides bacteremia, compared with deaths of patients with bacteremia due to aerobic gram-negative rods, were less likely to occur early after onset of bacteremia. Choice of antimicrobial therapy had no obvious relationship to eventual outcome. Nonobstetrical Bacteroides bacteremia identifies a group of patients at high risk of death during hospitalization. The diversity of both clinical and microbiologic features of these infections, however, makes specific recommendations regarding optimum therapy difficult to formulate.
In this study, 197 strains of Bacteroides genus from different species and origins were evaluated with regard to their susceptibility to 5-nitroimidazoles (5-Ni)-such as tinidazole, ornidazole, and metronidazole-using the agar dilution method. The presence of nim genes was also investigated by polymerase chain reaction. It was found that 5.6% of Bacteroides strains among all origins showed decreased susceptibility (minimum inhibitory concentrations varying from 4 to 16 microg/ml) to at least one of the imidazoles studied without any known nim gene associate. Also, we detected one strain isolated from a polluted aquatic environment in which one nim gene was found and characterized as nim B using restriction fragment length polymorphism and sequencing. Hence, resistance to 5-Ni should be monitored closely because they constitute, among few drugs, the ones quite effective in treating Bacteroides infections.
BACKGROUND: Hyperlactatemia is a metabolic complication of hypermetabolic, hyperdynamic sepsis. An important mechanism responsible for elevating plasma lactate concentrations in sepsis is altered regulation of the pyruvate dehydrogenase complex (PDH) in skeletal muscle. We investigated the ability of a specific tumor necrosis factor binding protein, TNFbp, to modulate lactate concentrations and skeletal muscle PDH activity in a rodent model of chronic abdominal sepsis. MATERIALS AND METHODS: We examined the regulation of lactate metabolism in four groups of animals: Control, Control + TNFbp, Septic, and Septic + TNFbp. Chronic (5 days) sepsis was induced by the creation of a stable intraabdominal abscess using a sterile fecal-agar pellet inoculated with E. coli plus B. Fragilis as the foreign body nidus. TNFbp (1 mg/kg/day) was injected subcutaneously daily. RESULTS: Sepsis increased plasma and skeletal muscle lactate concentrations 2-fold compared with control. In septic rats treated with TNFbp, plasma and skeletal muscle lactate concentrations were significantly decreased compared with untreated septic rats. In skeletal muscle, sepsis resulted in a 70% decrease in the proportion of the PDH in the active form compared with controls. The sepsis-induced inhibition in the PDH complex activity was prevented by TNFbp. PDH kinase was enhanced 1.8-fold in sepsis, and the increase in PDH kinase activity was prevented by treatment with TNFbp. TNFbp treatment did not have any effects on plasma lactate or the proportion of active skeletal muscle PDH activity in control animals. CONCLUSIONS: TNFbp prevents the sepsis-induced hyperlactatemia and derangements in skeletal muscle lactate concentrations and PDH activity. These observations suggest that TNF is an important mediator responsible for lactate dyshomeostasis during sepsis.
Complicated intra-abdominal infections usually mandate prompt surgical intervention supplemented by appropriate antimicrobial therapy. The aim of this study was to demonstrate that ertapenem was not inferior to piperacillin-tazobactam for the treatment of community-acquired intra-abdominal infections. A randomized open-label active-comparator clinical trial was conducted at 48 medical centers on four continents from December 2001 to February 2003. Adult patients with intra-abdominal infections requiring surgery were randomized to receive either ertapenem 1 g daily or piperacillin/tazobactam 13.5 g daily in 3-4 divided doses. The primary analysis of efficacy was the clinical response rate in clinically and microbiologically evaluable patients at the test-of-cure assessment 2 weeks after completion of therapy. All treated patients were included in the safety analysis. Patient demographics, disease characteristics, and treatment duration in both treatment groups were generally similar. The most commonly isolated pathogens at baseline were E coli (greater than 50% of cases in each group) and B fragilis ( approximately 9%). Favorable clinical response rates were 107/119 (90%) for ertapenem recipients and 107/114 (94%) for piperacillin/tazobactam recipients. The frequencies of drug-related adverse events, most commonly diarrhea and elevated serum alanine aminotransferase levels, were similar in both treatment groups. Six of 180 ertapenem recipients (3%) and two of 190 piperacillin/tazobactam recipients (1%) had serious drug-related adverse experiences. In this study, ertapenem and piperacillin/tazobactam were comparably safe and effective treatments for adult patients with complicated intra-abdominal infections.
Bacteroides infection frequently complicates surgery, instrumentation, or trauma to the alimentary, upper respiratory, and female genitourinary tracts. Bacteroides sp, alone or with other organisms, also may cause infections in the ear, nose, and throat, and other tissues where defeneses are lowered. Foul-smelling pus, sinus drainage, material from an abscess or infected traumatic wound, or a blood culture made because of a suspected anaerobic complication should be subjected to anaerobic study in the laboratory. Treatment of clinical bacteroidosis consists of specific antibiotics, surgery, oxygen under pressure, and appropriate local dressings. Treatment is often more effective if at least two antibiotics are given concurrently, and antibiotic sensitivity tests are recommended to select the best combination.
Ninety-six wound infections due to Bacteroides fragilis occurring after intestinal surgery are described. Most infections followed appendicectomy or colectomy for diverticulitis. B. fragilis was isolated in pure growth from 47 per cent of infections, and in mixed culture the other common bacteria were Klebsiella spp., Escherichia coli and Enterobacter spp. Fifty-three per cent of the infections responded rapidly to either non-specific measures or antibiotic therapy, but 47 per cent of patients developed complications, usually abscess formation. The successful isolation of bacteroides from clinical material requires special precautions. The specimen for bacteriological examination must be sent to the laboratory in a transport medium which maintains an anaerobic environment and the culture techniques must include a selective agar for the isolation of anaerobic bacteria. The role of antibiotic therapy in preventing postoperative wound infection after intestinal surgery is discussed. Bacteroides has an unusualy pattern of antibiotic susceptibility and it is essential that an effective antibiotic such as lincomycin is included in the treatment of infection originating from the intestinal tract.
Bacteriophage infecting Bacteroides fragilis, one of the most abundant bacteria in the human colon, have been proposed as indicators of virological faecal pollution. The first identification of a receptor for a bacteriophage in B. fragilis is reported here. First, resistant mutants were characterized following phage inactivation, and it was shown that cell wall proteins are involved in phage binding. Then the proteins involved were identified by various approaches: (i) comparison of the protein profiles of wild-type B. fragilis HSP40 and phage-resistant mutants; (ii) application of a modification of the virus overlay protein blot assay (VOPBA). At least two proteins of B. fragilis, with apparent molecular masses of 35 +/- 5 kDa and 65 +/- 5 kDa, bind to B40-8. This result was later confirmed by running a complex consisting of this phage bound to radiolabelled proteins of B. fragilis on an immunoaffinity column loaded with a specific antibody against the phage. Cell proteins retained in the column also coincided with the proteins that differed in the profiles of resistant mutants. Finally, to identify the potential function of these two proteins, their N-terminal sequences were determined and compared to published sequences, but no homologies were found.
There is limited information regarding the correlation of anaerobic susceptibility testing and outcome in the treatment of Bacteroides fragilis infections. We retrospectively analyzed the clinical outcomes of B. fragilis infections in patients treated with cefoxitin; the analysis was blinded for susceptibility results. Isolates of B. fragilis were tested by multiple agar dilution methods, disk elution, and commercial broth microdilution methods. Of 19 patients analyzed, 11 were cured and 8 were treatment failures. No significant differences existed between the groups with respect to age, sex distribution, weight, APACHE II score, dose of cefoxitin, or bacteremia. Failure was associated with a longer cefoxitin dosing interval (P = 0.019), a longer duration of hospitalization (P = 0.038), and decreased duration of cefoxitin treatment (P = 0.05). Four agar dilution systems (brucella plus blood, Wilkins-Chalgren, Wilkins-Chalgren plus blood, brain heart infusion plus blood) and two broth systems (Wilkins-Chalgren microdilution and a commercial system [Micromedia; Beckman, Carlsbad, Calif.]) all demonstrated lower geometric mean MICs for isolates from the group of patients that could be cured. Only the commercial broth microdilution medium (Micromedia) demonstrated a significantly reduced geometric mean MIC (P = 0.056). By using a logistic regression analysis, the shorter cefoxitin dosing interval (P = 0.0004) and the lower geometric mean MIC (P = 0.0088) in the commercial broth microdilution system were shown to be independent predictors of treatment success. These data suggest that the time that the concentration of cefoxitin is over the MIC for B. fragilis may be an important predictor of treatment success.
Anaerobic bacteria are important pathogens in head and neck infections such as chronic otitis media, chronic sinusitis, chronic mastoiditis, head and neck abscesses, cervical adenitis, parotitis, and postoperative infection. Bacteroides sp (Bacteroides melaninogenicus group, Bacteroides oralis, and Bacteroides fragilis group), Peptostreptococcus sp, and Fusobacterium sp predominate. The observed recent increase in the number of beta-lactamase-producing strains of Bacteroides sp isolated in head and neck infections has been associated with increased failure rates of the penicillins in the management of these infections. The pathogenicity of these organisms is expressed through their ability not only to survive penicillin therapy but also to shield penicillin-susceptible pathogens from the drug. Because of these direct and indirect virulent characteristics of anaerobic bacteria, appropriate antimicrobial therapy must be directed against all pathogens in mixed infections.
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Computed tomography (CT) was used to evaluate 15 rabbits with experimentally induced liver abscesses. The animals were examined both before and after intravenous contrast injection. After sacrificing the animals, postfreeze CT scans were made to mark the abdomen for 1-cm thick whole body sections for correlating the gross pathology with the results of the CT scans. CT detected 15 abscesses in 13 of the 14 rabbits with true positive lesions. Ten abscesses less than 1.4 cm in diameter were not detected by CT. Contrast agent enhancement was helpful in 70% of the studies. These abscesses have characteristics similar to human liver abscesses, but there was more gas and calcium in the experimentally induced abscesses than is encountered in humans with hepatic abscesses. The model and its CT characteristics appear well suited for future studies in the diagnosis and treatment of liver abscesses.