Amelioration of the Cost of Conjugative Plasmid Carriage in Eschericha coli K12

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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Pheromone-Responsive Conjugative Vancomycin Resistance Plasmids in Enterococcus faecalis Isolates from Humans and Chicken Feces

Applied and Environmental Microbiology ◽

10.1128/aem.00749-06 ◽

2006 ◽

Vol 72 (10) ◽

pp. 6544-6553 ◽

Cited By ~ 36

Author(s):

Suk-Kyung Lim ◽

Koichi Tanimoto ◽

Haruyoshi Tomita ◽

Yasuyoshi Ike

Keyword(s):

Drug Resistance ◽

Enterococcus Faecalis ◽

Multiple Drug Resistance ◽

Horizontal Transmission ◽

Vancomycin Resistance ◽

Conjugative Plasmid ◽

Farm Animals ◽

Multiple Drug ◽

Resistance Determinants ◽

Chicken Feces

ABSTRACT The drug resistances and plasmid contents of a total of 85 vancomycin-resistant enterococcus (VRE) strains that had been isolated in Korea were examined. Fifty-four of the strains originated from samples of chicken feces, and 31 were isolated from hospital patients in Korea. Enterococcus faecalis KV1 and KV2, which had been isolated from a patient and a sample of chicken feces, respectively, were found to carry the plasmids pSL1 and pSL2, respectively. The plasmids transferred resistances to vancomycin, gentamicin, kanamycin, streptomycin, and erythromycin to E. faecalis strains at a high frequency of about 10−3 per donor cell during 4 hours of broth mating. E. faecalis strains containing each of the pSL plasmids formed clumps after 2 hours of incubation in broth containing E. faecalis FA2-2 culture filtrate (i.e., the E. faecalis sex pheromone), and the plasmid subsequently transferred to the recipient strain in a 10-min short mating in broth, indicating that the plasmids are responsive to E. faecalis pheromones. The pSL plasmids did not respond to any of synthetic pheromones for the previously characterized plasmids. The pheromone specific for pSL plasmids has been designated cSL1. Southern hybridization analysis showed that specific FspI fragments from each of the pSL plasmids hybridized with the aggregation substance gene (asa1) of the pheromone-responsive plasmid pAD1, indicating that the plasmids had a gene homologous to asa1. The restriction maps of the plasmids were identical, and the size of the plasmids was estimated to be 128.1 kb. The plasmids carried five drug resistance determinants for vanA, ermB, aph(3′), aph(6′), and aac(6′)/aph(2′), which encode resistance to vancomycin, erythromycin, kanamycin, streptomycin, and gentamicin/kanamycin, respectively. Nucleotide sequence analyses of the drug resistance determinants and their flanking regions are described in this report. The results described provide evidence for the exchange of genetic information between human and animal (chicken) VRE reservoirs and suggest the potential for horizontal transmission of multiple drug resistance, including vancomycin resistance, between farm animals and humans via a pheromone-responsive conjugative plasmid.

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Vibrio cholerae O139 Multiple-Drug Resistance Mediated by Yersinia pestis pIP1202-Like Conjugative Plasmids

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00375-08 ◽

2008 ◽

Vol 52 (11) ◽

pp. 3829-3836 ◽

Cited By ~ 44

Author(s):

Jing-Cao Pan ◽

Rong Ye ◽

Hao-Qiu Wang ◽

Hai-Qing Xiang ◽

Wei Zhang ◽

...

Keyword(s):

Drug Resistance ◽

Yersinia Pestis ◽

Vibrio Cholerae ◽

Dna Sequences ◽

Multiple Drug Resistance ◽

Eastern China ◽

Early Period ◽

Plasmid Transfer ◽

Conjugative Plasmid ◽

Multiple Drug

ABSTRACT A conjugative plasmid, pMRV150, which mediated multiple-drug resistance (MDR) to at least six antibiotics, including ampicillin, streptomycin, gentamicin, tetracycline, chloramphenicol, and trimethoprim-sulfamethoxazole, was identified in a Vibrio cholerae O139 isolate from Hangzhou, eastern China, in 2004. According to partial pMRV150 DNA sequences covering 15 backbone regions, the plasmid is most similar to pIP1202, an IncA/C plasmid in an MDR Yersinia pestis isolate from a Madagascar bubonic plague patient, at an identity of 99.99% (22,180/22,183 nucleotides). pMRV150-like plasmids were found in only 7.69% (1/13) of the O139 isolates tested during the early period of the O139 epidemic in Hangzhou (1994, 1996, and 1997); then the frequency increased gradually from 60.00% (3/5) during 1998 and 1999 to 92.16% (47/51) during 2000 to 2006. Most (42/51) of the O139 isolates bearing pMRV150-like plasmids were resistant to five to six antibiotics, whereas the plasmid-negative isolates were resistant only to one to three antibiotics. In 12 plasmid-bearing O139 isolates tested, the pMRV150-like plasmids ranged from approximately 140 kb to 170 kb and remained at approximately 1 or 2 copies per cell. High (4.50 × 10−2 and 3.08 × 10−2) and low (0.88 × 10−8 to 3.29 × 10−5) plasmid transfer frequencies, as well as no plasmid transfer (under the detection limit), from these O139 isolates to the Escherichia coli recipient were observed. The emergence of pMRV150-like or pIP1202-like plasmids in many bacterial pathogens and nonpathogens occupying diverse niches with global geographical distribution indicates an increasing risk to public health worldwide. Careful tracking of these plasmids in the microbial ecosystem is warranted.

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The cost of multiple drug resistance inPseudomonas aeruginosa

Journal of Evolutionary Biology ◽

10.1111/j.1420-9101.2009.01712.x ◽

2009 ◽

Vol 22 (5) ◽

pp. 997-1003 ◽

Cited By ~ 66

Author(s):

H. WARD ◽

G. G. PERRON ◽

R. C. MACLEAN

Keyword(s):

Drug Resistance ◽

Multiple Drug Resistance ◽

Multiple Drug ◽

The Cost

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A Transferable 20-Kilobase Multiple Drug Resistance-Conferring R Plasmid (pKL0018) from a Fish Pathogen (Lactococcus garvieae) Is Highly Homologous to a Conjugative Multiple Drug Resistance-Conferring Enterococcal Plasmid

Applied and Environmental Microbiology ◽

10.1128/aem.00039-09 ◽

2009 ◽

Vol 75 (10) ◽

pp. 3370-3372 ◽

Cited By ~ 12

Author(s):

Takeshi Maki ◽

Mudjekeewis D. Santos ◽

Hidehiro Kondo ◽

Ikuo Hirono ◽

Takashi Aoki

Keyword(s):

Drug Resistance ◽

Enterococcus Faecalis ◽

Causative Agent ◽

Multiple Drug Resistance ◽

Conjugative Plasmid ◽

Multiple Drug ◽

Fish Pathogen ◽

Lactococcus Garvieae ◽

S Gene ◽

Dry Sausage

ABSTRACT Lactococcus garvieae, the causative agent of lactococcosis, has evolved strains that are highly resistant to antibiotics. Here, the 20,034-bp sequence of L. garvieae conjugative plasmid pKL0018 was determined. It contained two ermB genes and one tetS gene and a backbone more than 96% identical to that of pRE25, an Enterococcus faecalis plasmid from dry sausage.

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