Evaluating the minimum active concentrations of penicillin G and V and of retard forms in clinical conditions.

Following several signals indicating the inefficiency of the clinical treatment with various penicillin preparations in some cases, we decided to study the seric penicillin concentrations in the patients hospitalized in the "V. Babes" Hospital of Infectious Diseases, after administration of the various Romanian made forms of penicillin currently used in the therapy of streptococcal infections and in the prophylaxis of the sequelae of these infections. The data obtained on groups exceeding 30 persons by using two methods of determining the penicillin concentrations the dilutions and the diffusimetric methods revealed protective penicillin seric levels satisfactory for penicillin G and Efitard, according to the present treatment schemes. After 5 days from Moldamin administration only 45.4% of children and 43.3% of adults were found to have satisfactory penicillin concentrations. The administration of penicillin V reaches active penicillin concentrations in terms of the dose administered. The paper points out only one of the causes which together with others (such as beta-lactamase production and tolerance), contribute to the unsuccessful treatment with various forms of penicillin.

Characteristics of Neisseria meningitidis strains isolated in Romania between 1986 and 1989.

499 N. meningitidis strains were studied, 454 being isolated from CSF and blood and 45 from nasopharynx. Meningococcal serogroup A was prevalent in 1986-1988, having a decreasing tendency from 84.90% in 1987 to 45.0% in 1989. Serogroup C increased from 0.86% in 1986 to 15% in 1989. All strains, examined by diffusiometric method, were sensitive to ampicillin, cephalotin, chloramphenicol and rifampin. For tetracycline, resistance ranged from 2.28 to 6.0% in 1987-1989. The frequency of 52.0-72.14% resistant to sulphamides strains seems to be due to serogroup A prevalence. Six N. meningitidis strains, isolated in 1989, proved to be moderately resistant to penicillin with MIC greater than or equal to 0.1 mcg/ml. The results indicate the necessity of a continuous surveillance of meningococcal infection, both from the point of view of serogroup circulation and also of antibiotics sensitivity.

Restriction and modification of typing phages by an R factor in S. typhi.

We have investigated the qualities of one R factor 552 discovered on a strain of S. typhi resistant to A, C, S, T, nontypable, isolated from stool cultures; from the same patient, before starting the treatment we isolated, from his blood sample, the strain S. typhi 221, sensitive to A, C, T, degraded phage-type Vi A. Factor R 552 fi- when infecting strains of S. typhi Vi A and of A degraded 221- leads to the conversion of the respective phage-types into non-typable ones, as a result of the restricting and modifying effect on phage Vi A and on the derivatives resulting from it. Derivative R 552-1 as a resistance marker to ampicilline has a restrictive effect on the phage of S. panama A 47 too. Not taking into account possible causes such as spontaneous mutation, lysogeny, and adsorption of phages, we reach for the conclusion that R factor 552, through is restrictive effect, is the only cause responsible for the existence in the same patient of two strains of S. typhi different from the point of view of phage-type and antibiotype.