Mapping of the nick site on conjugative plasmid pVT745 by interrupted mating

Abstract Although plasmids can provide beneficial functions to their host bacteria, they might confer a physiological or energetic cost. This study examines how natural selection may reduce the cost of carrying conjugative plasmids with drug-resistance markers in the absence of antibiotic selection. We studied two plasmids, R1 and RP4, both of which carry multiple drug resistance genes and were shown to impose an initial fitness cost on Escherichia coli. To determine if and how the cost could be reduced, we subjected plasmid-containing bacteria to 1100 generations of evolution in batch cultures. Analysis of the evolved populations revealed that plasmid loss never occurred, but that the cost was reduced through genetic changes in both the plasmids and the bacteria. Changes in the plasmids were inferred by the demonstration that evolved plasmids no longer imposed a cost on their hosts when transferred to a plasmid-free clone of the ancestral E. coli. Changes in the bacteria were shown by the lowered cost when the ancestral plasmids were introduced into evolved bacteria that had been cured of their (evolved) plasmids. Additionally, changes in the bacteria were inferred because conjugative transfer rates of evolved R1 plasmids were lower in the evolved host than in the ancestral host. Our results suggest that once a conjugative bacterial plasmid has invaded a bacterial population it will remain even if the original selection is discontinued.

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First Description of KPC-2-ProducingKlebsiella oxytocaIsolated from a Pediatric Patient with Nosocomial Pneumonia in Venezuela

Case Reports in Infectious Diseases ◽

10.1155/2014/434987 ◽

2014 ◽

Vol 2014 ◽

pp. 1-4 ◽

Cited By ~ 1

Author(s):

Indira Labrador ◽

María Araque

Keyword(s):

Pediatric Patient ◽

Carbapenem Resistance ◽

Control Measures ◽

University Hospital ◽

Conjugative Plasmid ◽

Effective Control ◽

Molecular Tests ◽

The Andes ◽

Clinically Significant ◽

Significant Class

During the last decade, carbapenem resistance has emerged among clinical isolates of the Enterobacteriaceae family. This has been increasingly attributed to the production ofβ-lactamases capable of hydrolyzing carbapenems. Among these enzymes,Klebsiella pneumoniaecarbapenemases (KPCs) are the most frequently and clinically significant class-A carbapenemases. In this report, we describe the first nosocomial KPC-2-producingK. oxytocaisolated from a pediatric patient with pneumonia admitted to the intensive care unit at The Andes University Hospital, Mérida, Venezuela. This strain was resistant to several antibiotics including imipenem, ertapenem, and meropenem but remained susceptible to ciprofloxacin, colistin, and tigecycline. Conjugation assays demonstrated the transferability of all resistance determinants, except aminoglycosides. The isolate LMM-SA26 carried a ~21 kb conjugative plasmid that harbored theblaKPC-2,blaCTX-M-8, andblaTEM-15genes. Although carbapenem resistance in the Enterobacteriaceae is still unusual in Venezuela, KPCs have a great potential to spread due to their localization on mobile genetic elements. Therefore, rapid detection of KPC-carrying bacteria with phenotypic and confirmatory molecular tests is essential to establish therapeutic options and effective control measures.

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Replication of Staphylococcal Multiresistance Plasmids

Journal of Bacteriology ◽

10.1128/jb.182.8.2170-2178.2000 ◽

2000 ◽

Vol 182 (8) ◽

pp. 2170-2178 ◽

Cited By ~ 53

Author(s):

Neville Firth ◽

Sumalee Apisiridej ◽

Tracey Berg ◽

Brendon A. O'Rourke ◽

Steve Curnock ◽

...

Keyword(s):

Sequence Similarity ◽

Heavy Metal Resistance ◽

Metal Resistance ◽

Replication Initiation ◽

Conjugative Plasmid ◽

Rolling Circle ◽

Segregational Stability ◽

Structural And Functional Properties ◽

Resistance Plasmids ◽

Genes Encoding

ABSTRACT Based on structural and functional properties, three groups of large staphylococcal multiresistance plasmids have been recognized, viz., the pSK1 family, pSK41-like conjugative plasmids, and β-lactamase–heavy-metal resistance plasmids. Here we describe an analysis of the replication functions of a representative of each of these plasmid groups. The replication initiation genes from theStaphylococcus aureus plasmids pSK1, pSK41, and pI9789::Tn552 were found to be related to each other and to the Staphylococcus xylosus plasmid pSX267 and are also related to rep genes of several plasmids from other gram-positive genera. Nucleotide sequence similarity between pSK1 and pI9789::Tn552 extended beyond theirrep genes, encompassing upstream divergently transcribed genes, orf245 and orf256, respectively. Our analyses revealed that genes encoding proteins related to the deducedorf245 product are variously represented, in several types of organization, on plasmids possessing six seemingly evolutionarily distinct types of replication initiation genes and including both theta-mode and rolling-circle replicons. Construction of minireplicons and subsequent functional analysis demonstrated that orf245is required for the segregational stability of the pSK1 replicon. In contrast, no gene equivalent to orf245 is evident on the conjugative plasmid pSK41, and a minireplicon encoding only the pSK41 rep gene was found to exhibit a segregational stability approaching that of the parent plasmid. Significantly, the results described establish that many of the large multiresistance plasmids that have been identified in clinical staphylococci, which were formerly presumed to be unrelated, actually utilize an evolutionarily related theta-mode replication system.

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Chromosomal mutations of Escherichia coli that alter expression of conjugative plasmid functions.

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.77.1.513 ◽

1980 ◽

Vol 77 (1) ◽

pp. 513-517 ◽

Cited By ~ 47

Author(s):

J. McEwen ◽

P. Silverman

Keyword(s):

Escherichia Coli ◽

Conjugative Plasmid ◽

Chromosomal Mutations

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Antagonism between Aminoglycosides and β-Lactams in a Methicillin-Resistant Staphylococcus aureus Isolate Involves Induction of an Aminoglycoside-Modifying Enzyme

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.46.5.1516-1521.2002 ◽

2002 ◽

Vol 46 (5) ◽

pp. 1516-1521 ◽

Cited By ~ 7

Author(s):

Takashi Ida ◽

Ryoichi Okamoto ◽

Masato Nonoyama ◽

Kazuhiko Irinoda ◽

Mizuyo Kurazono ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Methicillin Resistant Staphylococcus Aureus ◽

Antimicrobial Activities ◽

Hybrid Structure ◽

Conjugative Plasmid ◽

Pcr Analysis ◽

Aminoglycoside Resistance ◽

Gene Encoding ◽

Methicillin Resistant ◽

Aureus Isolate

ABSTRACT We encountered three clinical isolates of methicillin-resistant Staphylococcus aureus which were susceptible to netilmicin and arbekacin in the absence of β-lactam antibiotics but which were resistant to them in the presence of β-lactam antibiotics. One of these strains, KU5801, was used to further investigate the antagonism between aminoglycosides and β-lactam antibiotics. β-Lactam antibiotics induced bacterial synthesis of aminoglycoside-6′-N-acetyltransferase and 2"-O-phosphotransferase [AAC(6′)-APH(2")] in association with decreased antimicrobial activities of aminoglycosides. A 14.4-kb EcoRI fragment that included the genes that control for β-lactam-inducible aminoglycoside resistance was cloned from a 31-kb conjugative plasmid present in KU5801. Restriction fragment mapping and PCR analysis suggested that a Tn4001-like element containing a gene encoding AAC(6′)-APH(2") was located downstream from a truncated blaZ gene. The DNA sequence between blaR1 and a Tn4001-like element was determined. The Tn4001-IS257 hybrid structure was cointegrated into the blaZ gene, and the typical sequences for the termination of transcription were not found between these regions. We deduced that antagonism of aminoglycosides by β-lactam antibiotics in isolate KU5801 involved transcription of the aac(6′)-Ie-aph(2")-Ia gene under the influence of the system regulating penicillinase production.

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