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PubMed1977

Anaerobic dechlorination and degradation of hexachlorocyclohexane isomers by anaerobic and facultative anaerobic bacteria.

Screening studies with strict and facultative anaerobic bacteria showed that Clostridium app. and several other representatives of Bacillaceae and Enterobacteriaceae actively degraded gamma-hexachlorocyclohexane (gamma-HCH) under anaerobic conditions. Representatives of Lactobacillaceae and Propronibacterium were inactive. With 36Cl-labelled gamma-HCH a nearly complete dechlorination was shown to occur in 4--6 days by Clostridium butyricum, C. pasteurianum and Citrobacter freundii, while other facultative anaerobic species were less active. Aerobically grown facultative anaerobes also dechlorinated actively gamma-HCH during subsequent anaerobic incubation with glucose, pyruvate or formate as substrates. The alpha-, beta- and delta-HCH isomers were also, but more slowly, dechlorinated (gamma larger than alpha larger than beta larger than or equal to delta-HCH). All species active in anaerobic degradation of gamma-HCH formed gamma-tetrachlorocyclohexene (TCH) as the main intermediate metabolite and no gamma-pentachlorocyclohexene (PCH) or other isomers of TCH or PCH have been found. Small amounts of tri- and tetrachlorinated benzenes have been found too. The mechanism of dechlorination is discussed.

Aerobiosis↗
PubMed1978

Anaerobic bacteremia as observed in a children's hospital. Clinically this may signify true anaerobic sepsis.

To ascertain the significance of anaerobic bacteremia in a children's hospital, the records of all patients whose blood cultures grew anaerobes during a 24-month period were reviewed. Anaerobes were isolated from 144 out of 1,126 blood cultures yielding bacteria. Anaerobic diphtheroid grew in 122 out of 143 anaerobic cultures, but only 4 out of 122 were isolated from patients with anaerobic sepsis. Nine per cent of the total episodes of anaerobic bacteremia occurred in 13 children who met out criteria for anaerobic sepsis; two oor more blood cultures obtained within a three-day period growing anaerobic bacteria, or an aerobe and an anaerobe, in a febrile child or one with an apparent infectious focus. Bacteroides accounted for 7 out of 13 (64 per cent) of the relevant isolates, while anaerobic diphtheroids 4 out of 13 (26 per cent) and anaerobic gram-positive cocci accounted for the remainder 2 out of 13 (18 per cent). Only one infant, with polymicrobial bacteremia, died, suggesting that anaerobic bacteremia is associated with less mortality in children than in adults. Anaerobic sepsis occurred in children who have had recent abdominal surgery, or who are immunosuppressed.

Adolescent↗
PubMed1978

Evaluation of a routine anaerobic subculture of blood cultures for detection of anaerobic bacteremia.

The value of a routine 48-h anaerobic subculture of blood cultures was assessed in our laboratory over a 4-month period. Excluding presumed contaminants, anaerobes represented 51 (6.9%) of the total number of 734 positive cultures. Sixteen isolates (all Bacteroides) from six patients were detected by the anaerobic subculture. All but one of these were also detected macroscopically. Excluding the one isolate, the routine anaerobic subculture hastened the identification of anaerobic organisms by only 1 day in two patients. We conclude that a routine anaerobic subculture is not indicated for the detection of anaerobic bacteremia.

Anaerobiosis↗
PubMed1977

Recovery of anaerobic, facultative, and aerobic bacteria from clinical specimens in three anaerobic transport systems.

With aspirated specimens from clinical infections, we evaluated the recovery of anaerobic, aerobic, and facultative bacteria in three widely used transport systems: (i) aspirated fluid in a gassed-out tube (FGT), (ii) swab in modified Cary and Blair transport medium (SCB), and (iii) swab in a gassed-out tube (SGT). Transport tubes were held at 25 degrees C and semiquantitatively sampled at 0, 2, 24, and 48 h. Twenty-five clinical specimens yielded 75 anaerobic strains and 43 isolates of facultative and 3 of aerobic bacteria. Only one anaerobic isolate was not recovered in the first 24 h, and then, only in the SGT. At 48 h, 73 anaerobic strains (97%) were recovered in the FGT, 69 (92%) in the SCB, and 64 (85%) in the SGT. Two problems hindered the recovery of anaerobes in the SCB and SGT systems: first die-off of organisms, as evidenced by a decrease in colony-forming units of 20 strains (27%) in the SCB and 25 strains (33%) in the SGT, as compared with 7 strains (9%) in the FGT, over 48 h; and second, overgrowth of facultative bacteria, more frequent with SCB and SGT. The FGT method was clearly superior at 48 h to the SCB and SGT systems in this study and is recommended as the preferred method for transporting specimens for anaerobic culture.

Aerobiosis↗
PubMed1978

Preparation of prereduced anaerobically sterilized media and their use in cultivation of anaerobic bacteria.

Several modifications of the roll-tube method have made it simpler for routine use in the isolation and growth of anaerobic bacteria. These include use of a check valve for the production of prereduced anaerobically sterilized media; a Salvarsan tube under oxygen-free gas pressure for the dispensing of molten prereduced anaerobically sterilized agar medium; a Kelly infusion bottle with a graduated pipette side arm (also under gas pressure) for quantitative delivery of fluid prereduced anaerobically sterilized media; and screw-capped prescription bottles for the cultivation of anaerobes. Colonies of Bacteroides melaninogenicus were easily identified and counted by this method. Other anaerobic bacteria have also been cultivated successfully.

Anaerobiosis↗
PubMed1979

Identification of some anaerobic bacteria in nonspecific anaerobic infections in animals.

Over 200 anaerobic bacterial isolates were recovered in a veterinary diagnostic laboratory from nonspecific infectious disease from 72 specimens originating from ten animal species. The majority of isolates were nonsporeforming bacteria and about half were identified to species. Bacteroides species formed the major group and included B. oralis, B. fragilis, B. corrodens, B. ruminicola subspecies ruminicola, B. ruminicola subspecies brevis and various subspecies of B. melaninogenicus. Gram-positive anaerobic cocci constituted the next major group of isolates and the main species identified in cattle was Peptococcus indolicus. Clostridial species were uncommon. Nine specimens yielded a pure culture of an anaerobe and, in samples containing mixtures of bacterial species, each specimen yielded an average of 3.1 anaerobic and 1.4 aerobic bacterial species. The failure to identify many of the isolates is discussed.

Anaerobiosis↗
PubMed1977

Anaerobic electron transport in anaerobic flagellum formation in Escherichia coli.

Flagellum formation by ubiquinone- and menaquinone-deficient mutant strains of Escherichia coli K-12 was studied under both aerobic and anaerobic growth conditions. Ubiquinone was found to be obligatory for aerobic flagellum formation but could be replaced by menaquinone for anaerobic flagellum formation. A mutant devoid of both quinones was immotile aerobically as well as anaerobically. Hence, the respective electron transport system is obligatory for flagellum formation in Escherichia coli.

Aerobiosis↗
PubMed1979

Anaerobic, non-clostridial fasciitis and myonecrosis of the abdominal wall. Pure anaerobic infection originating from neglected inflammation of an urachal remnant.

A pure anaerobic infection of the abdominal wall of a 40-year-old man is described. The infection originated from an urachal remnant. Seven different bacterial strains were isolated. Even though no clostridia were involved, the infection caused extensive necrosis of the abdominal wall including both fascia and muscles.

Abdominal Muscles↗
PubMed1978

Bone infections involving anaerobic bacteria.

Over 700 cases of anaerobic osteomyelitis have been reported in the literature. Nonetheless, most reviews of osteomyelitis have paid little attention to the potential role of anaerobes in bone infections. There have, as yet, been no prospective studies of osteomyelitis utlizing optimal anaerobic transport and culture techniques. In a retrospective study of osteomyelitis at Wadsworth VA Hospital from 1973--1975, 39 percent of 58 patients with osteomyelitis had an infection involving anaerobes. Anaerobes were isolated from 81 percent of 27 patients whose specimens were cultured anaerobically. Anaerobes were isolated from nine of ten samples of bone. Anaerobic bacteria were part of a mixed flora involving facultative bacteria in all but two cases. All of the patients with anaerobic infection had non-hematogenous osteomyelitis. Non-hematogenous disease comprises 80--90 percent of the osteomyelitis seen in adults. Our experience at Wadsworth VA Hospital and a review of the literature lead us to believe that anaerobes play a much larger role in osteomyelitis than has been appreciated previously. Infections of the calvarium, mastoid, mandible, maxilla and the extremities are most likely to involve anaerobes. Predisposing conditions include paranasal sinusitis, otitis media, periodontal disease, trauma, peripheral vascular disease, peripheral neuropathy and/or chronic osteomyelitis. The presence of a foul odor is a valuable clinical clue to the presence of anaerobes. Bacteroides, fusobacteria and anaerobic cocci have been reported with almost equal frequency from anaerobic bone infections. While Bacteroides fragilis is the most common anaerobe isolated in infections of other organ systems, it does not appear to be a common pathogen in anaerobic bone infections. The role of anaerobes in osteomyelitis is not yet resolved. They have been isolated in pure culture from infected bone, and under those circumstances are clearly pathogenic. Anaerobes are found more frequently as part of a mixed flora with facultative streptococci, gram-negative bacilli, and less often with S. aureus. In this setting it is unclear which organism or organisms are the primary invaders, or whether there is a synergistic mechanism of infection. The reliability of sinus drainage cultures also remains to be determined. Our retrospective study suggests that certain anaerobes isolated from sinus drainage are not present in infected bone. Cultures of bone or an abscess adjacent to bone would be expected to give more reliable data. The majority of anaerobes other than B. fragilis are susceptible to levels of penicillin achievable with parenteral administration of the antibiotic. Anaerobic pathogens should be sought in the situations noted above. We feel that parenteral penicillin should be part of the initial antibiotic regimen in patients with suspected or documented anaerobic bone infection...

Actinomycosis↗
PubMed1979

Metronidazole in the prevention and treatment of anaerobic sepsis.

Clinical trials were carried out in order to determine the value of metronidazole in preventing the development of anaerobic infections after surgery. Following a successful controlled trial of hysterectomy patients, among whom the prophylactic use of oral metronidazole resulted in a reduction of the anaerobic sepsis rate from 25% to nil, further trials were carried out with patients having urgent appendicectomy, those having elective colonic surgery and pregnant women having delivery by the vaginal and caesarean routes. These studies were conducted as double-blind trials in which metronidazole was compared with a placebo; patients were randomly allocated to the two "drug" groups. Since completion of the hysterectomy trial over 618 hysterectomies have been performed under metronidazole cover, none of which were complicated by anaerobic sepsis. Among appendicectomy patients, anaerobic infection did not develop in any of the 49 patients who received prophylactic metronidazole, but bacteriologically confirmed clinical anaerobic infections developed in 9 (19%) of 46 control patients. Since completion of the trial over 1098 appendectomies have been performed under metronidazole cover, only two of which developed an anaerobic infection. Among colonic surgery patients, anaerobic infections did not develop in any of 27 patients who received prophylactic metronidazole, but bacteriologically confirmed clinical anaerobic infections developed in 11 (58%) of 19 control patients. Since completion of the trial over 126 colonic operations have been performed under metronidazole cover, none of which were complicated by anaerobic sepsis. Pregnant women having vaginal delivery were not especially prone to anaerobic infections so that metronidazole prophylaxis is not indicated in these patients. Delivery by caesarean section appears to carry a risk of post surgical anaerobic sepsis in about 20% of patients not protected with metronidazole prophylaxis. Metronidazole is regarded as the drug of choice for the treatment of those non-clostridial anaerobic infections that require antimicrobial therapy. It may be given orally, rectally, intravenously and topically, has virtually no side effects and its use is characterized by a strikingly rapid and sustained clinical and microbiological response.

Anaerobiosis↗
PubMed2026

The anaerobic fungus Caecomyces churrovis produces H2 via a non-bifurcating NADH-dependent enzyme complex.

UNLABELLED: Hydrogenosomes are mitochondrion-derived organelles that produce ATP and H2 to support energy metabolism in anaerobic eukaryotes. H2 production allows reoxidation of reduced cofactors generated during fermentative metabolism; however, the metabolic mechanisms for H2 production in anaerobic eukaryotes remain incompletely understood. In particular, it remains unclear whether anaerobic fungi (AF) hydrogenosomes use a ferredoxin-dependent pathway or a distinct mechanism to regenerate NAD(P)+ and link electron transfer to H2 formation. Here, by combining genomic search, proteomic analysis, and enzymology, we reveal the molecular mechanism for H2 production in the AF Caecomyces churrovis. Our enzyme assays on the organelle fraction of C. churrovis revealed the activity of H2:NAD+ oxidoreductase but not pyruvate:ferredoxin oxidoreductase, which is usually linked to H2 formation. We identified genes encoding [FeFe] hydrogenase (Hyd) and NADH dehydrogenase subunits E and F (NuoE and NuoF) in C. churrovis and confirmed their expression in the isolated hydrogenosomal fractions by proteomic analysis. Combining the individually purified enzymes, we found Hyd and NuoEF proteins formed H2 directly from NADH independently of ferredoxin, functioning as a non-bifurcating NADH-dependent enzyme rather than an electron-bifurcating enzyme known from anaerobic prokaryotes. We identified homologs of hydrogenosomal NuoE, NuoF, and Hyd in many other AF, indicating this pathway is commonly shared among the AF. This work demonstrates the existence of a non-bifurcating NADH-dependent enzyme complex for H2 production in eukaryotes. Moreover, this complex could potentially be exploited as a target for controlling AF H2 production and altering fungal metabolism. IMPORTANCE: H2 production is a prominent feature of anaerobic energy metabolism, yet our understanding of eukaryotic mechanisms remains limited. Anaerobic fungi (AF) are key decomposers of lignocellulose and contribute to hydrogen flux in anaerobic environments. Although it has been more than 40 years since the H2 production in Neocallimastix was first reported, the molecular mechanism for hydrogenosomal H2 production and redox balance remains unclear. We demonstrate that AF produce H2 from NADH utilizing a non-bifurcating NADH-dependent enzyme complex rather than an electron-bifurcating, ferredoxin-dependent variant. We show that this enzyme complex is conserved across multiple AF lineages and thus demonstrate the occurrence of a non-bifurcating NADH-dependent enzyme in eukaryotes. This discovery expands our understanding of eukaryotic hydrogenosomal metabolism, reveals a previously unknown strategy for redox balancing, and highlights potential targets for manipulating H2 production. These insights have broad implications for microbial energy metabolism, anaerobic ecosystems, and bioengineering of H2-producing systems.

Hydrogen↗
PubMed1979

Anaerobic pulmonary infections.

The main cause of anaerobic pulmonary infections is aspiration of saliva, upper airway secretions or gastric content. Predisposing conditions include prominent dental disease, chronic upper respiratory tract infections and reduced consciousness. Fusobacterium nucleatum, Bacteroides melaninogenicus and anaerobic Gram-positive cocci are the most frequently encountered organisms. The clinical presentations are lung abscess, lung gangrene and empyema, which all tend to take a slow and indolent course. Preferred localization are dependent lung segments, most often on the right side. For bacteriological examination in these infections, only transtracheal aspirate and aspirate from the lung or pleural space are considered adequate. In 26 cases of empyema treated in our hospital during the last 3 years, adequate specimens had been taken in 19. Fifteen had been adequately examined, and anaerobes were cultured in 6. Among 29 abscesses treated during the same period, adequate specimens had been taken in only 14, and 11 had been properly examined. Seven specimens grew anaerobes on culture. In prospective studies of transtracheal aspirate in 15 chronic bronchitics without emphysema, anaerobes were not demonstrated. In 11 patients with bronchiectasis, anaerobic bacteria were cultured in 3. Finally, no anaerobic bacteria could be demonstrated in the transtracheal aspirate from 76 patients with acute exacerbation of chronic bronchitis. Anaerobic, pulmonary infections do not represent an intriguing medical problem in our region. However, knowledge of these infections is necessary to secure adequacy in collection of specimens and in their bacteriological examination.

Bacterial Infections↗