[Antibiotic resistance of revertant cultures of Streptococcus group A and of unclassified streptococci isolated from the blood of rheumatism patients].

Sensitivity of one strain of group A Streptococcus, its L-form and revertant was tested to 7 antibiotics and it was observed that the revertant was highly resistant to beta-lactam antibiotics and lincomycin, tolerant to ristomycin and had a high value of MBcC/MIC for erythromycin and tetracycline. Testing of other analogous revertant strains showed the same results. In streptococcal strains freshly isolated from blood of patients with rheumatism and resistant to some antibiotics there were recorded by electron microscopy heterogeneity of their population and presence in it of a significant number of cells with altered (unevenly thickened) cell walls and cells with microcapsules on the cell wall surface characteristic of the revertants. In vivo occurrence of streptococcal revertants may be the cause of their antibiotic resistance which obviously requires correction of the rational antibiotic therapy schemes.