Colon and rectal cancer together account for an estimated 92,500 new cancer cases in the U.S. annually, more than any other organ site; large bowel cancer results in an estimated annual mortality of 47,400, being second only to lung cancer in this regard (1). The median survival time for colon cancer patients is only 2.2 years. Recent epidemiologic studies are of great interest since they offer prospects of preventing this very serious form of cancer. Japan is one of a number of countries with a low incidence of large bowel cancer. However, Japanese migrating to the U.S. and adopting the western diet develop this cancer with increased frequency, approaching that of native Amencans (1). Hill et al. (2) have postulated that intestinal
The antimicrobial susceptibility of 492 anaerobic bacteria, the majority of which were. recent clinical isolates, was determined by the agar dilution technique. Penicillin G was active against most of the strains tested at 32 U or less/ ml, but only 72% ofBacteroides fragilis strains were susceptible at this level and 9% required 256 U or more/ml. Ampicillin was effective against most of the strains except B. fragilis at 16 ug or less/ml. Amoxicillin was active against only 31% of B. fragilis, 76% of other Bacteroides species, and 67% of Fusobacterium species at 8 ,ug/ml. Two new penicillins, mezlocillin and azlocillin, were similar to ampicillin in their activity. Carbenicillin and ticarcillin inhibited all but a few strains at 128 ,ug or less/ml. BLP 1654 was somewhat more active than penicillin G against B. fragilis but had similar activity against other anaerobes. Cephalothin was inactive against B. fragilis, and only 65% of other Bacteroides species were inhibited by 32 ug or less/ml. It was effective against all other anaerobes at that level. Cefamandole showed somewhat greater activity than cephalothin against B. fragilis but generally less activity against gram-positive organisms. Cefazaflur (SKF 59962) was comparable to cephalothin against B.firagilis. Cefoxitin was distinctly more active than cephalothin against B.fragilis. These latter two agents were less active than cephalothin against the gram-positive anaerobes. Chloramphenicol remains active against anaerobic bacteria at 16 ,ug or less/ml, with rare exceptions. Thiamphenicol was similar to chloramphenicol in its activity. Clindamycin was very active against most ofthe anaerobes at 8 ,ug or less/ml. Erythromycin and josamycin were also tested, with josamycin showing greater activity against B. fragilis than either erythromycin or clindamycin. A new oligosaccharide, everninomicin B, was less active than clindamycin against B. fragilis but more active against clostridia and some of the other strains tested. Most of the groups of bacteria tested demonstrated a trend toward resistance to tetracycline. Doxycyline and minocycline were somewhat more active than was tetracycline. Metronidazole was active against the majority of the anaerobes tested; resistance ws demonstrated by some of the gram-positive cocci and gram-positive, non-sporeforming bacilli.
A comparison of 13 vegetarian Seventh Day Adventists with 14 nonvegetarian Adventists revealed relatively few statistically significant differences in fecal flora. A separate study involved a comparison of vegetarian Adventists (49 subjects), nonvegetarian Adventists (45), and non-Adventists on a conventional American diet (31) re: the incidence of the C. paraputrificum group in the fecal flora. The Adventist groups had significantly fewer C. septicum and C. tertium isolates than the non-Adventists. Reference to earlier diet studies done by our group revealed certain striking differences. Fusobacterium and C. perfringens counts were very low and lactobacillus counts very high in Adventists as compared with Japanese-Americans on either a Japanese or Western diet or Caucasian individuals on a conventional U.S. diet. Comparison of nonvegetarian Adventists with the other groups on a nonvegetarian Western diet also revealed several statistically significant differences. Finally, there were a number of significant differences in fecal flora when high risk groups (Japanese-Americans on Western diet and Caucasians on conventional U.S. diet) were compared with low risk groups (Japanese-Americans on a Japanese diet and Adventists).
A total of 193 bacterial strains were tested for their susceptibilities to 14 antimicrobial agents. Penicillin G was active at 2 U/ml against 98% of the oral isolates. Other antibiotics with good activity were cefoperazone, moxalactam, Sch 29,482, and clindamycin. Metronidazole was active against more than 90% of the anaerobic bacteria and Capnocytophaga but was inactive against most other microaerophilic and facultative strains.
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.
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