Electron-microscopic study of conjugative plasmids of serologically typed strains ofEscherichia coli AP1

Plasmid DNAs isolated from cells ofE. coli AP1 were studied by electron microscopy. Two plasmid DNAs (FBI-1 and FBI-2) with molecular weights of 35.9±0.5×10⁶ and 51.5±0.6×10⁶ daltons respectively were identified.Department of Biology and General Genetics, P. Lumumba Peoples' Friendship University, Moscow. Laboratory of Genetics of Viruses, Institute of Biochemistry and Physiology of Microorganisms, Academy of Sciences of the USSR, Pushchino-on-Oka. (Presented by Academician of the Academy of Medical Sciences of the USSR N. N. Zhukov-Verezhnikov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 87, No. 4, pp. 328–330, April, 1979.     

Role ofEscherichia coli host cells in genetic control of plasmid transfer

Department of Biology and General Genetics, Patrice Lumumba Peoples' Friendship University, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR T. T. Berezov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 106, No. 8, pp. 214–217, August, 1988.     

Surface exclusion systems of F-like plasmids ofE. coli and their genetic control

Department of Biology and General Genetics, Patrice Lumumba Peoples' Friendship University, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR T. T. Berezov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 110, No. 9, pp. 303–306, September, 1990.     

Dissemination of IncFII plasmids carrying rmtB and qepA in Escherichia coli from pigs,farm workers and the environment

Fifty-one fluoroquinolone-resistant Escherichia coli isolates recovered from pigs, workers and environmental samples in one pig farm were screened for 16S rRNA methylase genes and qepA, a fluoroquinolone efflux pump gene, by PCR. Clonal relatedness of the E. coli isolates was examined by pulsed-field gel electrophoresis (PFGE), multilocus sequence typing and phylogenetic analysis. Plasmids from the E. coli isolates were characterized by incompatibility group, restriction enzyme digestion and Southern hybridization analysis. The genetic environment of rmtB and qepA was also determined by PCR mapping. Eleven isolates that were highly resistant to amikacin and fluoroquinolones were positive for rmtB and qepA. All of these isolates belonged to phylogenetic group A, but most of them had different PFGE patterns or belonged to different sequence types (STs). Four isolates from different sources (two from pigs, one from a farm worker and one from an environmental sample) belonged to the same ST (ST160). Both rmtB and qepA were located on approximately 75-kb IncFII conjugative plasmids with nearly the same EcoRI digestion pattern. Tn3, IS26 and ISCR3 were found to be associated with rmtB and qepA. This study has found, for the first time, the transmission of rmtB and qepA among E. coli isolates from pigs, farm workers and the environment. Both horizontal transfer of IncFII plasmids and clonal dissemination have occurred and been seen to contribute to the dissemination of these resistance genes in a pig farm.     

Concurrent emergence of multidrug resistance and heat resistance by CTX-M-15-encoding conjugative plasmids in Klebsiella pneumoniae

A plasmid-encoded ClpK protein was recently identified as a predictor of a heat-resistant phenotype in the opportunistic pathogen Klebsiella pneumoniae. This study was undertaken to evaluate the presence of the clpK gene in extended-spectrum β-lactamase (ESBL)-producing K. pneumoniae and to assess the probable co-transfer of multi-resistance with the heat resistance phenotype. A Danish collection of 80 ESBL-producing K. pneumoniae bloodstream infection isolates was screened for clpK by colony hybridization. Nineteen isolates (24%) were positive for clpK; some of them representing major clones identified in Denmark. Among these, nine isolates belonged to a single K. pneumoniae CTX-M-15 clone with sequence type (ST)16 exhibiting a heat-resistant phenotype. This clone has a multi-hospital occurrence and has also been detected outside Denmark. Horizontal co-transfer of multiple antibiotic resistances, including the CTX-M-15 resistance determinant, and the heat resistance phenotype was observed. Thus, the clpK gene is harbored by different ESBL-producing K. pneumoniae isolates including a clone of ST16 internationally spread. The co-localization of clpK on transferable ESBL-encoding plasmids allowing co-dissemination of multiple drug resistance with bacterial heat resistance is a highly interesting phenomenon that may further complicate the prevention of spreading of certain successful clones of multi-resistant K. pneumoniae.     

Genetic properties of transposons Tn6-1, Tn6-2, and Tn19-1

Department of Biology and General Genetics, Patrice Lumumba Peoples' Friendship University, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR, D. S. Sarkisov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 106, No. 9, pp. 347–349, September, 1988.     

Incompatibility and replication of plasmids

Department of Biology and General Genetics, Patrice Lumumba Peoples' Friendship University, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR A. D. Ado.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 112, No. 10, pp. 409–411, October, 1991.     

Comparative genomic analyses of IncpA1763-KPC plasmids

Multi-replicon plasmids harboring the Inc_pA1763-KPC replicon together with other replicons are being increasingly reported among Enterobacteriaceae species. However, plasmids with single Inc_pA1763-KPC replicons are poorly studied as a different incompatibility (Inc) group, despite their rise in appearance in some strains. Inc_pA1763-KPC plasmids, pA1763-KPC, and p427113-2, from two clinical Klebsiella pneumoniae isolates were fully sequenced by high-throughput genome sequencing. Linear structural comparisons of Inc_pA1763-KPC backbone region were made between these two plasmids and six arbitrarily selected representative Inc_pA1763-KPC plasmids sequenced previously. A further detailed genomic comparison was carried out between plasmids pA1763-KPC, p427113-2, and pFB2.2, which show high homology across the backbone sequence to one another. Among all sequenced Inc_pA1763-KPC plasmids considered in this study, plasmids pA1763-KPC and p427113-2 showed the most complete Inc_pA1763-KPC backbones. These were composed of the Inc_pA1763-KPC replicon (repA_{IncpA1763-KPC} and its iterons), the 5.6-kb Inc_pA1763-KPC-type maintenance region, the 27.7-kb IncFII_K-type maintenance region, and the 36.6-kb IncFII_K-type conjugal transfer regions. Compared with pA1763-KPC or p427113-2, the backbone regions of the other analyzed Inc_pA1763-KPC plasmids had gradually undergone different deletions or truncations, but shared small and core Inc_pA1763-KPC backbones including the Inc_pA1763-KPC replicon, Inc_pA1763-KPC-type maintenance region, and residual IncFII_K-type maintenance region. Accessory modules integrated into Inc_pA1763-KPC backbones included the multidrug-resistant module bla_KPC-2 region in pA1763-KPC, the metal-resistance modules ars region together with ncr region in pFB2.2 and sil in pKPN-9a0d, the ISKpn14-to-IS26 region in p427113-2, and other non-resistance region in the respective plasmids. This detailed comparative genomics analysis of Inc_pA1763-KPC plasmids provides a deep insight into their diversification and evolution.     

Compatibility of F-like plasmid FB1drd with standard F-group plasmids in strains of Escherichia coli K12

Compatibility of derepressed F-like plasmid FB1drd, integrated into the chromosome ofEscherichia coli K12 cells with standard plasmids of compatibility groups FI-FVI was studied. The results show that such plasmids can coexist in a stable state in the same cell with plasmid FB1drd. This suggests that it belongs to a new compatibility group (FVII).Department of Biology and General Genetics, Patrice Lumumba Peoples' Friendship University. Research Laboratory of Experimental Immunobiology, Academy of Medical Sciences of the USSR, Moscow. Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 85, No. 6, pp. 718–719, June, 1978.     

Evolution of gentamicin and arsenite resistance acquisition in Ralstonia pickettii water isolates

Ralstonia pickettii are ubiquitous in water environments. Members of this species are frequently, but not always, resistant to both gentamicin and arsenite. Gentamicin and arsenite co-resistance and the putative molecular mechanisms were investigated. A group of 37 R. pickettii strains isolated from drinking water and hospital wastewater were characterized for gentamicin and arsenite resistance phenotypes, the number and size of plasmids, and screened for genetic elements associated with arsenite tolerance, Integrative and Conjugative Elements (ICEs), among other. The genomes of three representative strains were compared.Most gentamicin resistant (GR) isolates (32/33) were resistant to arsenite, and harbored ICE- and ars operon-related genes. These genetic elements were not detected in any of the five arsenite susceptible strains, regardless of the GR (n = 1) or gentamicin susceptibility (GS) (n = 4) phenotype. The comparison of the genomes of two GR (one resistant and one susceptible to arsenite) and one GS strains suggested that these phenotypes correspond to three phylogroups, distinguished by presence of some genes only in GR isolates, in addition to point mutations in functional genes. The presence of ICEs and ars operon-related genes suggest that arsenite resistance might have been acquired by GR lineages.