As a part of the study on Sennetsu rickettsiosis, serological survay of inhabitants in Miyazaki district was carried out to clarify the prevarence of Rickettsia sennetsu by immunofluorescent antibody test using antigen prepared from infected L cells. The results obtained were as follows:
1) Rickettsial suspension prepared from infeced L cells, was specific enough for the test and was superior in simplicity for preparation.
2) Antibody titers of the sera obtained from 7 cases contracted the disease 15 years ago were 1: 16 to 1: 32, showing long persistence of antibody for the rickettsia.
3) Of 592 serum specimens obtained from inhabitants in Miyazaki district, 48 specimens showed antibody titers of 1: 16 or higher.
4) Antibody positive cases ranged mostly to age groups above 30. The incidence of male was supposed to be twice as much as of female. In geographical distribution most cases were inhabitants in Miyazaki City or closely neighboring areas.

View full abstract

Strains of Bacteroides fragilis, being highly resistant against some β-lactam antibiotics (Penicillin, Sulbenicillin, Cephalothin) especially by the hyperinoculation of 10¹⁰ bacterial cells per ml, made strains of drug-sensitive enteric bacteria grow aerobically on the drug-containing media.
These sensitive strains, mixed either washed cells or culture filtrate of resistant B. fragilis, grew on the media containing the drugs in 100μg/ml or higher concentration.
However, when the inoculum size of 10¹⁰ cells/ml of B. fragilis in mixed culture was reduced to 10⁶ cells/ml, the growth of the sensitive strains on the drug-containig media became disproportionaly poor. In addition, no strain of the enteric bacteria obtained from the mixed culture could be subcultured on the same drug-containing media.
From these experiments, it appeared that this growth of the enteric bacteria was not resulted from the transfer of R plasmid from the drug-resistant B. fragilis, but from the inactivation of the antibiotics by the resistant organisms.
The ability of B. fragilis to inactivate β-lactam antibiotics was detected in the supernatant of washed and sonicated cell-suspension as well as culture filtrate at early logarithmic phase of bacterial growth. As this inactivating ability was especially remarkable to cephalothin, the essential nature of this ability might be due to cephalosporinase of B. fragilis.
Among the strains of B. fragilis which did not show the drug-inactivating ability in the mixed culture experiments, some strains were as highly resistant as drug-inactivating strains on the sensitivity tests carried out with 10⁶ cells per ml. However, they were neither so resistant on the tests with 10¹⁰ cells/ml, nor they produced any cephalosporinase in their culture filtrate though a certain enzymatic activity was demonstrated in their cells.
Amount of resistant anaerobes and their cephalosporinase or β-lactamase activity should always be considered at the chemotherapy in which any β-lactam antibiotics is applied.

View full abstract

Time course studies were carried out on splenic lymphoid cell subpopulations, serum antibody titer and weight of the spleens in mice infected with Rickettsia sennetsu and Rickettsia tsutsugamushi of high and low virulent strains.
1. All of the mice infected with R. sennetsu Miyayama strain died in two weeks. In this case, weight of the spleens and the number of lymphoid cells, both T and B cells, increased trasiently at the time of manifestation of symptoms, and decreased later at the late stage.
When the mice infected with R. sennetsu Miyayama strain were treated with tetracycline, the spleens enlarged till the convalescence and then constricted to near normal range. They enlarged with the recrudescence and constricted again when symptoms of the mice became severe, and the mice died finally in spite of the treatment. In lymphoid cell subpopulations of the spleens, T cells began to increase first at a start of the treatment. Increase of B cells, on the other hand, ocurred later at the convalescence. Lymphoid cell subpopulations of the spleens returned to normal range temporarily when the mice were recovered by the treatment. However, the number of lymphoid cells of the spleens, both T and B cells, decreased again when the mice had a relapse of the disease and became in a critical condition after discontinuance of tetracycline therapy.
High titers of serum antibodies were observed at the 4th week after infection and were maintained even when the mice relapsed into the disease and were in a critical condition.
2. Most of the mice infected with Gilliam strain of high virulent R. tsutsugamushi died in two weeks. In this case, weight of the spleens and lymphoid cell subpopulations of the spleens showed changes similar to those observed in mice infected with R. sennetsu. But occasionally some of the mice were long-survived. In these mice, the spleens enlarged till the convalescence and then constricted to near normal range. In lymphoid cell subpopulations, T cells increased first prior to the convalescent stage, whereas, increase of B cells ocurred when the mice recovered.
High titers of serum antibodies were observed at the 4th week after infection and were maintained for a long time.
3. The mice infected with Irie strain of low virulent R. tsutsugamushi progressed subclinically. In this case, the spleens began to enlarge from the 2nd week to the 3rd or the 4th week after infection and c/a then constri ted to near normal r nge. T cells in the spleens began to increase at the 2nd week. On the other hand, B cells continued to decrease till the 3rd week and then increased. Finally, the number of lymphoid cells of the spleens and their subpopulations recovered to normal range.
Serum antibodies were detected at the 2nd week after infection. They reached to high titers at the 4th week and were maintained in high titer for a long time.
These findings suggested that increase of T cells had a very important role on recovering from rickettsial infections and that humoral immunity could not prevent the development of the rickettsial infections but cellular immunity could prevent it.

View full abstract

Type A influenza viruses were isolated and identified in the U.S.S.R. on November, 21, 1977. Among them was isolated type H1N1 virus which was different from type H3N2 virus prevailing all over the world since 1968. The type H1N1 virus has been isolated from the subsequent epidemics of influenza in Japan and other countries in the world.
In Kawasaki City, Kanagawa prefecture, double epidemics of type H1N1 and H3N2 influenza broke out almost simultaneously over a period from January to March, 1978. The number of patients involved was the largest at the beginning of February. About 6, 700 primary and secondary schoolchildren were absent from school during this period. The rate of classes closed for the prevention of spread of the epidemic was higher in lower secondary schools than in primary schools. For healthy subjects serum hemagglutination-inhibiting (HI) antibody was examined before the outbreak of epidemics. It was found that rate of possession of such antibody against strain H3N2 prevailing in the epidemic was very low, regardless of the age. On the other hand, none of those who were less than 20 years old had such antibody against strain H1N1.
After the epidemics were over, primary schoolchildren were examined for serum antibody against type H1N1 virus. As many as 55.4 per cent of them were negative for the antibody.

View full abstract