Vera L. Sutter

Anaerobic Pyogenic Liver Abscess

Abstract The role of anaerobic bacteria in the etiology of pyogenic liver abscess has not been fully recognized. In 11 years we have encountered 25 cases of anaerobic liver abscess, which represent...

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...

Toxigenicity and antimicrobial susceptibility ofClostridium difficile, a cause of antimicrobial agent-associated colitis

Fourteen of 16 strains ofClostridium difficile, a recently recognized cause of antimicrobial agent-associated ileocolitis in laboratory animals and colitis in man, were found to be toxigenic. The susceptibility of these isolates to a variety of antimicrobial agents provides information that may be of value in assessing the means by whichC. difficile may produce colitis, in developing selective bacteriologic media for diagnosis, and in selecting appropriate antimicrobial therapy for colitis.

Treatment of Anaerobic Infections with Metronidazole

The results of treatment of 10 patients with anaerobic infections with metronidazole are presented. Six patients were cured, three showed initial good response but circumstances required a change to another drug, and one patient did not respond. The unique spectrum of the drug, its pharmacology, and limitations are discussed. The results indicate that further clinical trials to determine the efficacy of metronidazole in the treatment of anerobic infections are indicated.

Treatment of anaerobic infections with lincomycin and clindamycin.

Abstract The efficacy of lincomycin and clindamycin against anaerobic bacteria was evaluated by in vitro sensitivity studies and clinical observations. Ninety-six per cent of 219 stock strains of v...

Fecal flora in different populations, with special reference to diet

Although potent antimicrobial agents may effect rapid and significant changes in fecal microflora, changes in diet or dietary supplements usually produce modest changes by comparison. It may be, however, that even such minor changes may result in significant changes in metabolic activity, particularly in terms of production of possible carcinogens or cocarcinogens. It is clear that significant changes may occur in metabolic activity without major qualitative or quantitative changes in the fecal microflora. Other research that might help explain the epidemiological observations of the association between diet and colon cancer would be studies of the flora at different levels of the gastrointestinal tract (particularly the cecum and small bowel), studies of the mucosa-associated flora at different levels, and long-term dietary studies.

Collaborative Evaluation of a Proposed Reference Dilution Method of Susceptibility Testing of Anaerobic Bacteria

An agar dilution method for susceptibility testing of anaerobic bacteria was evaluated to determine whether results obtained would be consistent enough to recommend it as a reference method. The study was conducted in 10 laboratories where the minimum inhibitory concentrations of six antibiotics (carbenicillin, cefoxitin, chloramphenicol, clindamycin, penicillin G, and tetracycline) were determined against 10 bacterial strains on Wilkins-Chalgren agar prepared by three manufacturers. Minimum inhibitory concentrations falling on the modes varied from 57 to 80% of all determinations and on the mode or within ±1 log2 dilution of the mode from 87 to 100% within each laboratory. When data from all laboratories were pooled, minimum inhibitory concentrations from each laboratory agreed with the overall mode 48 to 71% of the time, with an overall agreement at ±1 log2 dilution of 96%. This degree of reproducibility allows for recommendation of the procedure as a reference method. Results with three of the test strains were very consistent, and these strains are recommended as control strains: Clostridium perfringens ATCC 13124, Bacteroides fragilis ATCC 25285 and Bacteroides thetaiotaomicron ATCC 29741. The minimum inhibitory concentrations for these strains were on the mode or within ±1 log2 dilution of the mode 98, 99, and 99% of the time, respectively. The remaining anaerobic bacteria are recommended as reference strains.

Susceptibility of Bacteroides fragilis to six antibiotics determined by standardized antimicrobial disc susceptibility testing.

The susceptibility of 100 or more strains of Bacteroides fragilis to six antibiotics was determined by standardized agar dilution and disc diffusion tests. Good correlation of results of the two methods was obtained with chloramphenicol, clindamycin, lincomycin, penicillin, and vancomycin. Correlation of results with erythromycin was not as good. A great deal of overlapping of zone diameters among strains classed as susceptible, intermediate, and resistant occurred with both erythromycin and lincomycin, making interpretation of disc diffusion tests difficult. All strains tested were susceptible to chloramphenicol; 94% were susceptible to clindamycin at concentrations readily achieved with ordinary dosage, and all strains were inhibited by 6.2 μg/ml, a level which is achieved with somewhat more intensive therapy. Only 7% were shown to be susceptible to erythromycin and 13% to lincomycin under the conditions of our testing procedure. Only a small percentage of the strains were susceptible to penicillin, and none was susceptible to vancomycin.

Susceptibility of Respiratory Tract Anaerobes to Orally Administered Penicillins and Cephalosporins

Anaerobic bacteria recovered from airway-related infections were tested by agar dilution against selected penicillins and cephalosporins available for oral administration. Against 136 isolates, penicillins G and V showed comparable activity, particularly when pharmacological differences were considered. Although many isolates were exquisitely susceptible to the penicillins, only 55% of the Bacteroides species and 72% of all isolates were inhibited at 0.5 μg of penicillin G per ml. Results for penicillin V at 1 μg/ml were similar (59 and 73%). The two cephalosporins were more active at achievable levels, inhibiting 94 to 95% of Bacteroides and 95 to 96% of all isolates at 8 μg/ml. These levels represent approximately 50% of the reported peak serum levels after oral administration of 625 mg of the penicillins and 500 mg of the cephalosporins. Dicloxacillin and nafcillin were tested against 50 isolates. The two were comparably active on a weight basis; dicloxacillin was more active when pharmacological differences were considered, but did not match the other penicillins or the cephalosporins.

A new approach to patients with suspected anaerobic postpartum pelvic infections. Transabdominal uterine aspiration for culture and metronidazole for treatment

Oral metronidazole was given as therapy in 25 women with the clinical diagnosis of a postpartum anaerobic soft tissue pelvic infection following a vaginal delivery. There was a good clinical response in 80 per cent of these women. No anaerobic organisms resistant to metronidazole were recovered in the treatment failures. Different specimen collection techniques were evaluated, with anaerobes recovered in 4 per cent of the blood cultures, 26.3 per cent of the transabdominal endometrial aspirations, and 88 per cent of the transcervical endometrial samples. The aerobic recovery of organisms was 4 per cent from blood cultures, 15.8 per cent from transabdominal endometrial aspirations, and 96 per cent from the transcervical approach. The significance of these findings is discussed.