One hundred fourty infants were subjected to study on the isolation frequency of Escherichia coli, sesitivity of the isolates to antibacterial drugs, and the distribution of R factor.
No strain was isolated from the infants under one hour of age. However, Escherichia coli strains were isolated from newborn infants between 24 hours and 72 hours with the frequency of 38.2%.
Among 76 strains of Escherichia coli isolated, 63 strains(82.9%) were resistant to one or moew of 6 antibacterial agents such as ampicillin(AP), kanamycin(KM), streptomycin(SM), cholamphenicol(CP), tetracycline(TC), and nalidixic acid(NA).
Among 63 resistant strains the most frequency found resistance was SM(81%), followed in the decreasing order of resistance by TC(58.7%), AP(42.9%), CP(38.1%) and NA(4.8%). None of the strains was resistant to KM.
Fourteen different drug resistant patterns were found and mostfrequently encountered resistant pattern was TC SM CP, and miltiple resistance strains was greater than single in the number of the strains and in the tranferability of resistance.
Eleven different R factors were isolated from resistant strains. Among them R(TC CP) factor was isolated most frequently. The percentage with antibacterial agents were lower than in the group of infants who had nor been treated, indicating that there is little correlation between pre-vious antibacterial therapy and the occurence of resistant Escherichia coli.
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