The investigation of staphylococci, especially their persistency, isolated from the mares of staffs and patients of J and K Hospital in 1956 and 1957, was carried out, using the examinations of biological characters, antibiotic sensitivity and phage-typing.
On the experimental infections of animal skin, inflammatory reactions were observed Rs indicator, and influences of antibiotics were also examined.
The experiments of inoculation on human nose, using resistent staphylococci, were tested.
Their results were as follows:
1) One thousand three hundred sixty four strains of staphylococci were isolated from 114 persons of both hospitals. Among those strains, 241 pigment-producing strains were found (18%), 202 coagulase-positive (15%), 343 mannite-fermenting (25%). By the long-termed observations of 114, 48 carriers of coagulase-positive staphylococci were detected.
2) The distribution of resistent srains was significantly different between J and K Hospital; the former being 31%, and the latter 54%. Concerning the kind of antibiotics, streptomycin resistent strains were mostly found in J Hospital, while on the other hand, in K Hospital, tetracycline resistent 46% and chloramphenicol resistent 30%. It is considered that the rate of resistent styains and the difference of the kind of antibiotic were closely connected with the frequency of use of the drug.
3) It was possible to classify 64% of those strains by using the phage-typing.
Most of those belonged to group 3 (66%), and resistent strains were also found mostly in group 3.
4) According to the continuous observation of 114 persons for a long period, the rate of persistently positive carriers of coagulase-positive strains was 18%, and that of the same phage-pattern 15%.
Persistence of certain strains was thus recognized, which was considered to be a possible the origin of an epidemic.
5) The strain of phage-pattern 77 was isolated in 17 instrances out of 25 persons at K Hospital (68%). A transmission and an infection from one person were recognized.
6) On the inoculating experiment of staphylococci on rabbit skin, the size of reaction zone of skin was measured; reaction by inoculation of resistent strain was slighter, but it had a tendency to develop by the use of antibiotic.
7) On the inoculation experiment of human nose using resistent strain against penicillin, the strain was continuously isolated, when penicillin was given; but, with out use of penicillin, no strain was found. Namely, when resistent strain was inoculated, the use of the antibiotic promoted the persistence of the strain on nasal mucous membrane.
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