[Experimental non-culturable Vibrio cholerae eltor and its biological properties]. / Eksperimental'noe poluchenie nekul'tiviruemykh form Vibrio cholerae eltor i kharakteristika ikh biologicheskikh svoistv.

In experiments with the cultivation of V. cholerae eltor under the conditions of high salt concentration, as well as low temperature and deficiency in nutrient substances, uncultivable forms (UF) of toxigenic and nontoxigenic vibrios were obtained. The absence of growth of seeded vibrios after the filtration of samples (with a filter of 0.22 micron), the preservation of specific antigenic determinants and the initial set of genes, changes in the morphology of cells (small size, coccoid form with the flagella retained) confirm the transition of V. cholerae eltor under study into the uncultivable state which, under unfavorable conditions, more rapidly develops in toxigenic vibrios than in nontoxigenic ones. The analysis of the INT-reductase activity of UF disintegrates revealed that they had endogenic respiration whose activity increased (4.5- to 6.5-fold) in the presence of the exogenic intermediates of the Krebs cycle. The uncultivable forms of the vibrios retain genes responsible for pathogenicity, as well as their antigenic determinants.

[Comparative antibiotic sensitivity of NAG vibrios]. / Sravnitel'naia chuvstvitel'nost' k antibiotikam NAG-vibrionov.

Six hundred and forty eight NAG vibrio strains isolated at various periods from patients and carriers and from environmental objects such as surface of water reservoirs and sewage were studied with respect to their sensitivity to 14 antibiotics with the method of serial dilutions in solid media. Irrespective of the isolation place, object and time, the NAG vibrios were highly resistant to penicillins and polymyxin M. At the same time they were highly sensitive to gentamicin (MIC 1-2 micrograms/ml), levomycetin (MIC 0.5-1 micrograms/ml) and tetracyclines (MIC 0.25-1 micrograms/ml). Study of the recipient capacity of NAG vibrios with respect to R plasmids showed that they could be recipients of exogenic R plasmids of various incompatibility groups.

[Transforming activity of R- and Lac-plasmids of clinical strains of Gram-negative bacteria]. / Transformiruiushchaia aktivnost' R- i Lac-plazmid klinicheskikh shtammov gramotritsatel 'nykh bakterii.

The isolated plasmid DNA of clinical strains of Gram-negative bacteria were shown to have transforming activity when E. coli strain 0600 and S. typhimurium strain LT-2 were used as recipients. The frequency of transformation depended on the recipient strain and the character of the plasmids. The presence of deletion mutants was revealed among the transformants. Such mutants occurred with varying frequency, most often in S. typhimurium strain LT-20; the reason for this phenomenon is at present under discussion. The transformation of plasmids controlling lactose splitting and their conjugation transfer into recipient S. typhimurium strain LT-2 is possible only under condition of using recipient (R+). The possibility of the formation of the cointegrate (R and lac plasmids) in recipient S. typhimurium strain LT-2 is discussed.

[Study of the transmissibility of multiple drug resistance and the capacity to ferment lactose in a clinical strain of Kl. pneumoniae]. / Issledovanie transmissivnosti mnozhestvennoi lekarstvennoi ustoichivosti i sposobnosti fermentirovat' laktozu u klinicheskogo stamma pneumonirobial. Kl.

The donor properties of K. pneumoniae PI 220 with multiple drug resistance were studied. It was shown that the above strain carried 2 plasmids, i.e. R-plasmid pPI 220 controling resistance to ampicillin, streptomycin, tetracycline, chloramphenicol, kanamycin and sulphanylamides and plasmid pPI 221 controlling lactose fermentation. Both plasmids can be transfered on conjugation to strain E. coli P678 at a temperture of 28 degrees C at a rate of 10(-5) for pPI 220 and 10(-4) for pPI 221. The drug resistance controlled by pPI 221 was transfered mainly in a "blocks" simultaneously to 6 drugs. Deletion of plasmid pPI 220 was observed rarely. The donor properties of the strain were defined by the conjugative plasmid pPI 220 controlling the self-transfer and mobilization of plasmid pPI 221 incapable of the self-transfer. E. coli P678 (pPI 220) (PPI 221) acquired the donor properties and transfered both plasmids to E. coli J62 on crossing simultaneously at a rate of 10(-2), as well as to S. typhimurium LT2 and P. rettgeri at a rate of 10(-5). In all the recipient strains studied the transfered plasmids were unstable and segregated also simultaneously at a rate being the highest for P. retgari PI 230. The clones with stable preservation of the plasmids could be obtained by selection.