Mechanism of amikacin resistance in Pseudomonas aeruginosa isolates from patients with cystic fibrosis

Hurley, James C.; Miller, George H.; Smith, Arnold L.

doi:10.1016/0732-8893(95)00138-6

Cited by 18 publications

(32 citation statements)

References 18 publications

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“…As indicated in Table 3, the selected Tic hs strains exhibited various levels of resistance to antipseudomonal aminoglycosides such as gentamicin (2-to 64-fold), amikacin (4-to 64-fold), and tobramycin (2-to 128-fold) as well as to enzymerecalcitrant test compounds like fortimicin (2-to Ͼ16-fold) (data not shown) and apramycin (2-to 64-fold) (data not shown) (71). These results were fully consistent with previously published data showing the absence of horizontally acquired aminoglycoside-modifying enzymes in most CF isolates of P. aeruginosa (29,45,70,83). As the efflux system MexXY-OprM is known to play a major role in emergence of aminoglycoside resistance in CF strains (31,83,84), we assessed its expression at the gene (mexY) and the protein (MexY) levels by reverse transcription RT-PCR and Western blotting, respectively.…”

Section: Resultssupporting

confidence: 79%

Efflux Unbalance in Pseudomonas aeruginosa Isolates from Cystic Fibrosis Patients

Vettoretti

Plésiat

Muller

et al. 2009

Antimicrob Agents Chemother

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Retrospective analysis of 189 nonredundant strains of Pseudomonas aeruginosa sequentially recovered from the sputum samples of 46 cystic fibrosis (CF) patients over a 10-year period (1998 to 2007) revealed that 53 out of 189 (28%) samples were hypersusceptible to the ␤-lactam antibiotic ticarcillin (MIC < 4 g/ml) (phenotype dubbed Tic hs ). As evidenced by trans-complementation and gene inactivation experiments, the mutational upregulation of the efflux system MexXY was responsible for various degrees of resistance to aminoglycosides in a selection of 11 genotypically distinct strains (gentamicin MICs from 2 to 64 g/ml). By demonstrating for the first time that the MexXY pump may evolve in CF strains, we found that a mutation leading to an F1018L change in the resistance-nodulation-cell division (RND) transporter MexY was able to increase pump-promoted resistance to aminoglycosides, cefepime, and fluoroquinolones twofold. The inactivation of the mexB gene (which codes for the RND transporter MexB) in the 11 selected strains showed that the Tic hs phenotype was due to a mutational or functional loss of function of MexAB-OprM, the multidrug efflux system known to contribute to the natural resistance of P. aeruginosa to ␤-lactams (e.g., ticarcillin and aztreonam), fluoroquinolones, tetracycline, and novobiocin. Two of the selected strains synthesized abnormally low amounts of the MexB protein, and 3 of 11 strains expressed truncated MexB (n ‫؍‬ 2) or MexA (n ‫؍‬ 1) polypeptide as a result of mutations in the corresponding genes, while 7 of 11 strains produced wild-type though nonfunctional MexAB-OprM pumps at levels similar to or even higher than that of reference strain PAO1. Overall, our data indicate that while MexXY is necessary for P. aeruginosa to adapt to the hostile environment of the CF lung, the MexAB-OprM pump is dispensable and tends to be lost or inactivated in subpopulations of P. aeruginosa.

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Section: Resultssupporting

confidence: 79%

Efflux Unbalance in Pseudomonas aeruginosa Isolates from Cystic Fibrosis Patients

Vettoretti

Plésiat

Muller

et al. 2009

Antimicrob Agents Chemother

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“…often the most common aminoglycoside resistance mechanism [62,89,137,148]), including isolates originally identified as resistant to amikacin (62,91,131), gentamicin (13,114), and tobramycin (89). In some instances, too, impermeability resistance occurs together with inactivating enzymes in promoting multiple aminoglycoside resistance in P. aeruginosa (89,(98)(99)(100)(101)127).…”

Section: Impermeabilitymentioning

confidence: 99%

Aminoglycoside Resistance inPseudomonas aeruginosa

Poole

2005

Antimicrob Agents Chemother

411

322

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“…Resistance has even evolved for drugs specifically designed to prevent selection for resistance (10,23,27,30,43,52,74,85,86). These factors underline the importance of understanding the genetic and phenotypic bases underlying antibiotic resistance and developing new strategies to combat the proliferation of resistant organisms.…”

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confidence: 99%

Reverse Engineering Antibiotic Sensitivity in a Multidrug-Resistant Pseudomonas aeruginosa Isolate

Struble

Gill

2006

Antimicrob Agents Chemother

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Antibiotic resistance is a pervasive and growing clinical problem. We describe an evaluation of a reverse engineering approach for identifying cellular mechanisms and genes that could be manipulated to increase antibiotic sensitivity in a resistant Pseudomonas aeruginosa isolate. We began by chemically mutating a broadly resistant isolate of P. aeruginosa and screening for mutants with increased sensitivity to the aminoglycoside amikacin, followed by performing whole-genome transcriptional profiling of the mutant and wild-type strains to characterize the global changes occurring as a result of the mutations. We then performed a series of assays to characterize the mechanisms involved in the increased sensitivity of the mutant strains. We report four primary results: (i) mutations that increase sensitivity occur at a high frequency (10 ؊2 ) relative to the frequency of those that increase resistance (10 ؊5 to 10 ؊10 ) and occur at a frequency 10 4 higher than the frequency of a single point mutation; (ii) transcriptional profiles were altered in sensitive mutants, resulting in overall expression patterns more similar to those of the sensitive laboratory strain PAO1 than those of the parental resistant strain; (iii) genes found from transcriptional profiling had the more dramatic changes in expression-encoded functions related to cellular membrane permeability and aminoglycoside modification, both of which are known aminoglycoside resistance mechanisms; and finally, (iv) even though we did not identify the specific sites of mutation, several different follow-up MIC assays suggested that the mutations responsible for increased sensitivity differed between sensitive mutants.Antibiotic resistance develops rapidly after the introduction of a new antibiotic and now exists, to some extent, for all antibiotics. Resistance has even evolved for drugs specifically designed to prevent selection for resistance (10,23,27,30,43,52,74,85,86). These factors underline the importance of understanding the genetic and phenotypic bases underlying antibiotic resistance and developing new strategies to combat the proliferation of resistant organisms. One approach has been to combine new and conventional antibiotics to simultaneously increase the sensitivities of resistant organisms and target essential genes (40,50,51,73). The success of such an approach is dependent upon the identification of genes and/or mechanisms that might be targeted to increase sensitivity. We report here on our efforts to evaluate a reverse engineering approach for identifying such genes and mechanisms. Specifically, we have identified aminoglycoside-sensitive mutants of a multiple-drug-resistant Pseudomonas aeruginosa isolate and characterized the global changes in gene expression associated with mutations that restored sensitivity in two of these mutants as well as the resistant parental strain and the sensitive laboratory strain PAO1.We chose to study a clinical isolate, named B1, that showed high levels of resistance to five aminoglycosides tested: amikacin,...

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Mechanism of amikacin resistance in Pseudomonas aeruginosa isolates from patients with cystic fibrosis

Cited by 18 publications

References 18 publications

Efflux Unbalance in Pseudomonas aeruginosa Isolates from Cystic Fibrosis Patients

Efflux Unbalance in Pseudomonas aeruginosa Isolates from Cystic Fibrosis Patients

Aminoglycoside Resistance inPseudomonas aeruginosa

Reverse Engineering Antibiotic Sensitivity in a Multidrug-Resistant Pseudomonas aeruginosa Isolate

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