A research on the influence of penicillin on beta­hemol ytic streptococcus and beta- lactamase positive Escherichia coli present in the same medium

The objective of our research is to show that the beta-lactamase positive E.coli derived from patients affect the treatment of beta-hemolytic Streptococcus present in the same medium. For this reason, it has been tried to demonstrate via in-vitro experiments, that in case when beta-lactamase positive E.coli are present together with beta-hemolytic Streptococcus, they are capable to make the therapy of penicillin ineffective. In our study, beta-lactamase positive E.coli obtained from urine culture of 25 of 150 patients are put into in-vitro experiments present in the same nutritive medium together with beta-hemolytic Streptococcus derived from throat cultures of different 25 patients. Beta-hemolytic Streptococcus in equal proportions have been compared with distinct dilutions of E.coli. After an one hour lasting incubation period, enumeration has been performed, by sowing the above taken samples into nutrition medium one consisting of sheep blood and the other of sheep blood plus nalidixic acid. Afterwards, by adding 0,1 ml (50, 100, 200 units) of penicillin solutions into each of these dilutions separately, they are sowed once more into nutrition mediums one consisting of sheep blood and the other of sheep bloodplus nalidixic acid. The reproducing colony enumerations have been determined. The colony enumerations of beta-lactamase positive E.coli and beta-hemolytic Streptococcus have been compared before penicillin has been added and after. And the beta-lactamase enzyme activities have been controlled again. As a conclusion; since the beta-lactamase positive E.coli dilutions have been made, a reduction has been observed in the number of beta-lactamase positive E.coli by going towards the 10"1, 10"2, 10"3, 10^ dilutions; and even if the 0,1 ml stock beta-hemolytic Streptococcus are added in equal amounts to these dilutions, the beta-hemolytic Streptococcus number in the 10"' dilutions has been observed to be decreased, because of the high density of beta-lactamase positive E.coli. On the contrary, the beta-hemolytic Streptococcus colony has been observed to be increasing by going towards the 10"4 dilutions; so that, even if the penicillin amount has been increased (50, 100, 200 units of penicillin), these results have been altered. A change has been experienced for the number of beta-hemolytic Streptococcus colony depending only on the penicillin. As to results of our study; it has been determined that beta- lactamase positive E.coli and beta-hemolytic Streptococcus, being present in the same medium, are capable to reproduce even in a small proportion in spite of penicillin.