Bacteriological examinations were made in fecal specimens obtaind from 293 healthy persons to isolate C. perfringens and to study their heat-resistance and distribution of Hobbs' serotypes. 1. C. perfringens was isolated from 50 (79.4%) out of 63 specimens examined by direct cultures with streaks of a loopful of feces per plate. The viable counts ranged from 103 to 108 cells per gram of feces, being 105 per gram or more in 47.6 per cent (30/63). The serotypable strains were isolated from 27.0 per cent of specimens (17/63), those serotyps varied among the ea h specimens. The most part of strains isolated from unheated specimens were found to be heat-sensitive. 2. C. perfringens was isolated from 78 (26.6%) out of 293 specimens examined which had been treated by heating for 60 minutes at 100°C. The serotypable strains were isolated from 11.9 per cent of specimens (35/293). Of the typable isolates, Hobbs' 13 and 1 were relatively frequent organisms. 4. The findings noted in this study indicate that it is of profound significance to the diagnosis of food poisoning due to heat-resistant C. perfringens, to make the count of viable cells of C. perfringens in feces from patients after heating at 100°C for 60 minutes as well as to assess heat-resistance of the organisms isolated from unheated feces by direct cultures.
A total of 635 specimens of foods on the market, including raw meat, processed meat and fish products and raw oysters, were examined for the presence of C. perfringens. The heat-sensitivity and serological relationships to Hobbs' 1-17 types of the isolates were investigated. 1. C. perfringens was isolated from 180 (47.5%) out of 379 unheated raw meat specimens, and heatresistant strains were isolated from 3 (0.8%) of these specimens. 2. After heating for 15 minutes a 80°C, C. perfringens was isolated from 63 (16.6%) out of 379 raw meat specimens, and heat-resistant strains were isolated from 18 (4.7%) specimens. 3. Heat-resistant C. perfringens was isolated from 36 (59.0%) out of 61 raw meat specimens of 30 gram each after heating for 30 minutes at 100°C. The heat-resistant and serotypable strains were isolated from 14 (23.0%) specimens. 4. C. perfringens was isolated from 9.3 per cent of processed meat and fish products (20/215) by cultures of unheated specimens, and from 6.1 per cent of those (5/82) by cultures of heat-treated specimens (80°C, 15 min.). Heat-resistant strains were isolated from 5/215 (2.3%) unheated specimens, and from 4/82 (4.9%) heat-treated specimens. 5. Raw oysters were shown to be markedly contaminated by C. perfringens, being demonstrable in 100.0 per cent (31/31) of specimens. Heat-resistant C. perfringens was not isolated from non heat-treated specimens, but from 14/31 (45.2%) heat-treated specimens. 6. The results obtained indicate that the most of C. perfringens which occur as contaminants of raw meat and other various foods are heat-sensitive strains. However, the isolation rates observed in cultures of heat-treated specimens (80°C or 100°C) suggest a considerably high incidence of contamination of raw meat, oyster, etc. by heat-resistant spores of this organism.
Following the previous papers, the studies on the growth of Pseudomonas aeruginosa in inorganic salt solutions are proceeding to the investigation of factors necessary for the multiplication of bacilli. In this paper, the results obtained in the experiment about the growth of 13 strains of Pseudomonas aeruginosa in NaC1 solution, are described. 1) It is certainly demonstrated that four of 13 strains quantitatively multiply in 0.85% NaC1 solution and others do not, whereas all the strains tested do not multiply in 0.01% NaC1 solution. 2) The growth of Pseudomonas aeruginosa which is able to multiply in 0.85% NaCl solution, is permitted in the solutions containing NaC1 at the final concentrations of 1% to 0.5%. The growth of bacilli could not be recognized beyond ranges between 0.5% and 1% of NaCl. 3) A possible generation time of the P-8 strain of Pseudomonas aeruginosa in 0.85% NaCl solution is 3.4 hours. 4) Such growth of Pseudomonas aeruginosa also occurred in KC1 or MgC12 solution under the isotonic condition. 5) It was confirmed that the growth of bacilli as mentioned above is not due to the presence of impurities involved in the salts, but the intrinsic effects of the salts themselves.