Kenichi Konishi

Antitumor effect of normal intestinal microflora on Ehrlich ascites tumor

In order to investigate the antitumor activity of intestinal microflora, the constitution of normal flora was examined in humans, guinea pigs and mice. It was clarified that Eubacterium, Bifidobacterium and Bacteroides were the predominant bacterial genera in humans. In addition, neither Clostridium nor Enterobacteriaceae was detected in guinea pigs and neither Clostridium nor Bifidobacterium was present in mice. Total bacterial counts in tumor‐bearing mice were reduced in comparison with those in normal mice. Especially, in the ileum of tumor‐bearing mice, the incidence of anaerobic bacterial genera was strikingly decreased. From the bacteria found, 59 living and killed strains isolated from intestinal microflora were examined for antitumor activity against Ehrlich ascites tumor. It was observed that 11 of the tested strains had antitumor activity. Four of these were toxic to the host, and in particular, all mice injected with Pseudomonas aeruginosa (TYM‐8) died within several days. Eubacterium lentum (TYH‐11), Propionibacterium acnes (TYM‐28), Proteus mirabilis (TYM‐7) and Serratia marcescens (TY‐142), in which anti‐tumor activity was recognized with living and formalin‐killed bacteria, cured the tumor‐bearing mice, and the culture supernatant of 5. marcescens contained apparent antitumor activity.

A Nosocomial Outbreak of Food Poisoning Caused by Enterotoxigenic Clostridium perfringens

Clostridium perfringens type A is a very common cause of human food poisoning. The food poisoning, which usually progresses mildly, is characterized by diarrhea and abdominal pain, and results from the ingestion of food contaminated with a large number of the cells (9, 10, 15). Since the first report of food poisoning by C. perfringens was presented (12), a considerable amount of research has been directed to clarify the nature of this type of food-borne disease. It is well known that the organism responsible for the food poisoning forms heat-resistant spores (9, 14, 15). In some cases, however, heat-susceptible C. perfringens was isolated as the causative agent (5, 8). The enterotoxin of this organism has been isolated, purified, characterized biologically, and shown to be the cause of the illness (2, 6, 7). We encountered an outbreak of diarrhea in 61 inpatients at a hospital in Toyama. At about 9 a.m. on March 14, 1980, some inpatients in the hospital developed gastroenteritis. The number of cases continued to rise until 9 a.m. on March 15, by which time 61 inpatients (23% of the total inpatients) were affected. Forty-five of the diarrheal inpatients (74%) developed this disorder between 12 a.m. and 9 p.m. on March 14. The average age of these patients at the time was 55.7 yr (range, 9 to 81 yr), and they were from 13 out of 18 clinics. All 61 affected inpatients had diarrhea as the main clinical feature. Twenty-five (41%) of the patients complained of abdominal pain, 3 (5%) vomiting and 2 (3%) thirst, but none had fever. One dehydrated patient required intravenous fluid. None of the patients died. Fifty-seven patients had one to 10 passages and the other four patients had 15 to 20 passages. In 51 patients the diarrhea ceased within 24 hr, and in the other 10 patients it ceased within 48 hr. Forty-four patients had watery diarrhea, II had bowel looseness and 6 had lienteric diarrhea. Investigations were begun on the morning of March 15. The diarrheal inpatients were examined clinically and their hospital records were reviewed. The dietary charts for March 12, 13, and 14 were also reviewed. Stools and rectal swabs from the diarrheal patients, some unaffected inpatients and all the kitchen-

Response of Ligated Rabbit Ileal Loop to Clostridium perfringens Type C Strains and Their Toxic Filtrates

The vegetative cells and toxic filtrates of Clostridium perfringens type C strains were injected into ligated rabbit ileal loops and the responses were observed. Out of 12 strains examined, 2 strains showed positive reaction in this test, when the vegetative cells were injected. One of these 2 strains was an enterotoxigenic and beta‐toxigenic and the other was beta‐ and delta‐toxigenic but not enterotoxigenic. Culture filtrates containing beta or delta toxin also showed fluid accumulation in the rabbit ileal loop. Histological findings of loops injected with culture filtrates containing beta toxin showed separated and effaced villi, hemorrhage in the mucosa, engorged vessels, inflammatory cell infiltration, and hyperplasia of the lymphoid tissue.

Growth of Clostridium perfringens in the guinea pig intestinal juice medium

モルモット腸内容物培地にClostridium perfringensの栄養型および芽胞型を接種した場合,高圧滅菌腸内容物培地中ではいずれも増殖性,芽胞化,発芽および生残性は良好であつた。未滅菌および上清腸内容物培地中では,栄養型を接種した場合,生残性および芽胞化は著しく悪く,この傾向は結腸内容物培地において顕著に認められた。芽胞型を接種した場合は,増殖性および発芽はほとんど認められなかつたのみでなく,芽胞型として接種菌量の1/10∼1/100程度に減少して生残した。ミリポアフィルター〓過腸内容物培地中では,栄養型を接種した場合,高圧滅菌腸内容物培地中と同様な成績を示す場合と,未滅菌腸内容物培地中と同様な成績を示す場合があることがおかつた。このことは腸内においては外来性の微生物に対してその増殖,発芽および芽胞化に対して常在菌の影響のほかに易熱性の抑制因子が存在して働くことを示すものと考えられる。胆汁酸の嫌気性菌に対する増殖抑制はC. perfringens>Bifidobacterium≥Bacteroides>Peptostreptococcusの順に小となつた。C. perfringensと各種嫌気性菌を同量,同時にTF培地に接種した場合,互いにまつたく影響を及ぼさなかつた。各種嫌気性菌を前培養したTF培地にC. perfringensを接種した場合,その増殖性はグラム陽性菌群およびBacteroidesにより強く抑制され,接種菌量以下に減少した。一方,Fusobacteriumは何ら影響を与えなかつた。以上を総括するとモルモット腸管内では先住細菌もしくはその代謝産物が,C. perfringensの発育,定着性に対して大きな影響を及ぼしていることを示唆している。