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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

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

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

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

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

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

Oxygen and "strictly anaerobic" intestinal bacteria. II. Oxygen metabolism in strictly anaerobic bacteria.

Oxygen metabolism of "strictly anaerobic" intestinal bacteria was investigated and compared in 25 strains. Washed cell suspensions of all the bacterial strains, in which growth in a medium initially equilibrated with a gas mixture consisting of 5% O2, 5% CO2, and 90% N2 was almost the same as under anaerobic conditions, absorbed O2 at high rate. Such O2 uptake was inhibited by NaN3. Most strains in which growth was inhibited either partially or completely in the same oxygenic condition absorbed O2 at a comparably low rate, and in many cases, such O2 uptake was not inhibited by NaN3. However, in a certain strain incapable of growth in the initial presence of dissolved O2, absorption of O2 was as high as that in some aerobic bacteria, and it was inhibited by NaN3. Little interrelationship was found between the degree of oxygen tolerance and the activities of NADH-peroxidase, H2O2-splitting reaction or superoxide dismutase. A slight interrelationship seems to be present in the case of NADH oxidase even though many exceptions were recognized. All the strains studied had the activities of superoxide dismutase, the absence of which has been regarded as the enzymatic basis of strict anaerobiosis of "strictly anaerobic" bacteria. Some strict anaerobes had high an activity of this enzyme as some aerobic bacteria. The differences in the levels of this activity seem to have some interrelationship not with differences in the degree of oxygen tolerance but with those in the genus to which every strain belongs taxonomically.

Anaerobiosis

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

Growth of clinical isolates of anaerobic bacteria on agar media: effects of media composition, storage conditions, and reduction under anaerobic conditions.

The quantitative growth, the colony size, and the rate of growth of 47 clinical anaerobic isolates were compared on five different media, namely Brucella agar, brain heart infusion agar, Columbia agar, Schaedler agar, and tryptic soy agar. There was no significant difference in the quantitative growth of the anaerobes inoculated onto the five media. Although no single medium was superior for the growth of all isolates, 12 of 22 isolates, inoculated onto media stored for 4 weeks or less, grew best on Schaedler agar. The effects of supplementation of the media with reducing agents and reduction of the media before use were also analyzed and were found to be affected by the composition and length of storage of the media, as well as the bacteria tested.

Agar

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

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