The frequencies of multiple-drug-resistant strains were investigated in
Staphylococcus aureus from 1965 through 1968 and in
Escherichia coli from 1966 through 1968 classifying them with each of the corresponding drugs.
The following changes were found during the periods of investigation.
S. aureus (7 drugs tested) : (1) In PC-G-resistant strains, there was a tendency for 5-drug-resistant and 6-drug-resistant strains to increase. (2) In SM-resistant strains, a tendency was noted for 5-drug-resistant strains to increase markedly. (3) In EM-resistant strains, for 4-drug-resistant strains showeda tendency to increase. (4) Almost no change was observed in the frequencies of multiple-drug-resistant strains comprising CP resistance. (5) In KM-resistant strains, a tendency was observed for 6-drug-resistant and 7- drug-resistant strains to increase. (6) No change was found in the frequencies, of multiple-drug-resistant strains comprising TC resistance. (7) In SIM-resistant strains, there was a tendency for 5-drug-resistant strains to increase.
E. coli (6 drugs tested) : (1) In SM-resistant strains, there was a tendency for 4-drug-resistant strains to decrease, while 5-drug-resistant strains increased. (2) In CP-resistant strains, a tendency was noted for 4-drug-resistant strains to decrease. (3) No change was found in the frequencies of multiple-drugresistant strains comprising KMresistance. (4) No change was found in the frequencies of multiple-drug-resistant strains comprising CET resistance. (5) In TC-resistant strains, there was a tendency for 5-drug-resistant strains toincrease. (6) In SIM-resistant strains, 3-drug-resistant strains showed a tendency to increase.
The possible processes for the development of the main types of multiple-drug-resistant strains were examined in light of their frequencies. The resultssuggest that the markers of resistance to TC, PC-G and SIM form a common basis of the various drug-resistance patterns in
S. aureus. It is inferred that various types of multiple-drug-resistant strains may be formed by the successive addition of SM, EM, CP and KM markers in this order to the TC, PC-G and SIM markers. It is similarly inferred that in
E. coli TC, SM and SIM markers form a commonbasis of various drug-resistance patterns and that various types of multiple-drug-resistant strains may be formed by the successive addition of CP and KM or CET markers in this order to the TC, SM and SIM markers. The pattern of KM resistance of various multiple-drug-resistant strains of
S. aureus and
E. coli was quite unique among the various drug resistances investigated.
In the preceding paper
1) the general tendency of drug-resistances of
Staphylococcus aureus (coagulase-positive) and
Escherichia coli. was reported on the strains clinically isolated in Japan during the past four years, 1965-1968. The purpose of this paper is to describe multiple-drug resistance in strains of the two species.
With regard to multiple-drug resistance, a number of studies have been already reported
2-5). However, few of these reports investigated annually and analysed statistically.
In view of previous results showing that the degrees of drug sensitivity are very different depending on the sources of isolation, we here used only the strains from the same source of isolation :
S. aureus strains were the isolates from pus specimens and
E. coli from urine. Also sulfamethoxazole was newly added to the drugs tested. The details of the investigations are described hereunder; first on
S. aureus and then on
E. coli.
View full abstract