[Screening of beta-lactamase inhibitors among representatives of the genus Micromonospora and the genus Streptoverticillium].

A total of 123 cultures of the genus Micromonospora and 89 cultures of the genus Streptoverticillium were studied for their capacity to produce beta-lactamase inhibitors. It was shown that streptoverticilla were highly resistant to beta-lactam antibiotics. No organisms producing beta-lactamase inhibitors were detected among the cultures of this genus. As for Micromonospora, 30 cultures (24.4 per cent) of this genus produced inhibitors. They were most frequently isolated from orange and brown cultures of Micromonospora. The inhibitors had no antibacterial activity, inhibited beta-lactamases of gram-negative bacteria and did not inhibit exogenic beta-lactamases of staphylococci. Their inhibitory activity was evident only with the use of isolated enzymes. With the use of intact growing cultures of gram-negative bacteria producing the same enzymes (Pseudomonas, Klebsiella, Enterobacter) no inhibitory activity was observed. Though the inhibitors had some features in common, they did not seem to be similar, since they had different spectra with respect to their effect on various beta-lactamases of gram-negative bacteria.