Journal article
Selection Pressure Required for Long-Term Persistence of blaCMY-2-Positive IncA/C Plasmids
Applied and environmental microbiology, Vol.77(13), pp.4486-4493
07/2011
Handle:
https://hdl.handle.net/2376/103395
PMCID: PMC3127679
PMID: 21602382
Abstract
Multidrug resistance
bla
CMY-2
plasmids that confer resistance to expanded-spectrum cephalosporins have been found in multiple bacterial species collected from different hosts worldwide. The widespread distribution of
bla
CMY-2
plasmids may be driven by antibiotic use that selects for the dissemination and persistence of these plasmids. Alternatively, these plasmids may persist and spread in bacterial populations in the absence of selection pressure if a balance exists among conjugative transfer, segregation loss during cell division, and fitness cost to the host. We conducted a series of experiments (both
in vivo
and
in vitro
) to study these mechanisms for three
bla
CMY-2
plasmids, peH4H, pAR060302, and pAM04528. Results of filter mating experiments showed that the conjugation efficiency of
bla
CMY-2
plasmids is variable, from <10
−7
for pAM04528 and peH4H to ∼10
−3
for pAR060302. Neither peH4H nor pAM04528 was transferred from
Escherichia coli
strain DH10B, but peH4H was apparently mobilized by the coresident trimethoprim resistance-encoding plasmid pTmpR. Competition studies showed that carriage of
bla
CMY-2
plasmids imposed a measurable fitness cost on the host bacteria both
in vitro
(0.095 to 0.25) and
in vivo
(dairy calf model). Long-term passage experiments in the absence of antibiotics demonstrated that plasmids with limited antibiotic resistance phenotypes arose, but eventually drug-sensitive, plasmid-free clones dominated the populations. Given that plasmid decay or loss is inevitable, we infer that some level of selection is required for the long-term persistence of
bla
CMY-2
plasmids in bacterial populations.
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Details
- Title
- Selection Pressure Required for Long-Term Persistence of blaCMY-2-Positive IncA/C Plasmids
- Creators
- Murugan Subbiah - Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WashingtonEva M Top - Department of Biological Sciences, Institute for Bioinformatics and Evolutionary Studies (IBEST), University of Idaho, Moscow, IdahoDevendra H Shah - Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WashingtonDouglas R Call - Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, Washington
- Publication Details
- Applied and environmental microbiology, Vol.77(13), pp.4486-4493
- Academic Unit
- Veterinary Microbiology and Pathology, Department of; Paul G. Allen School for Global Animal Health
- Publisher
- American Society for Microbiology; 1752 N St., N.W., Washington, DC
- Identifiers
- 99900546635401842
- Language
- English
- Resource Type
- Journal article