Dataset Information

Efflux-mediated resistance to tigecycline (GAR-936) in Pseudomonas aeruginosa PAO1.

ABSTRACT: Pseudomonas aeruginosa strains are less susceptible to tigecycline (previously GAR-936; MIC, 8 micro g/ml) than many other bacteria (P. J. Petersen, N. V. Jacobus, W. J. Weiss, P. E. Sum, and R. T. Testa, Antimicrob. Agents Chemother. 43:738-744, 1999). To elucidate the mechanism of resistance to tigecycline, P. aeruginosa PAO1 strains defective in the MexAB-OprM and/or MexXY (OprM) efflux pumps were tested for susceptibility to tigecycline. Increased susceptibility to tigecycline (MIC, 0.5 to 1 micro g/ml) was specifically associated with loss of MexXY. Transcription of mexX and mexY was also responsive to exposure of cells to tigecycline. To test for the emergence of compensatory efflux pumps in the absence of MexXY-OprM, mutants lacking MexXY-OprM were plated on medium containing tigecycline at 4 or 6 micro g/ml. Resistant mutants were readily recovered, and these also had decreased susceptibility to several other antibiotics, suggesting efflux pump recruitment. One representative carbenicillin-resistant strain overexpressed OprM, the outer membrane channel component of the MexAB-OprM efflux pump. The mexAB-oprM repressor gene, mexR, from this strain contained a 15-bp in-frame deletion. Two representative chloramphenicol-resistant strains showed expression of an outer membrane protein slightly larger than OprM. The mexCD-OprJ repressor gene, nfxB, from these mutants contained a 327-bp in-frame deletion and an IS element insertion, respectively. Together, these data indicated drug efflux mediated by MexCD-OprJ. The MICs of the narrower-spectrum semisynthetic tetracyclines doxycycline and minocycline increased more substantially than did those of tigecycline and other glycylcyclines against the MexAB-OprM- and MexCD-OprJ-overexpressing mutant strains. This suggests that glycylcyclines, although they are subject to efflux from P. aeruginosa, are generally inferior substrates for P. aeruginosa efflux pumps than are narrower-spectrum tetracyclines.

SUBMITTER: Dean CR

PROVIDER: S-EPMC149306 | biostudies-literature | 2003 Mar

REPOSITORIES: biostudies-literature

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Publications

Efflux-mediated resistance to tigecycline (GAR-936) in Pseudomonas aeruginosa PAO1.

Dean Charles R CR Visalli Melissa A MA Projan Steven J SJ Sum Phaik-Eng PE Bradford Patricia A PA

Antimicrobial agents and chemotherapy 20030301 3

Pseudomonas aeruginosa strains are less susceptible to tigecycline (previously GAR-936; MIC, 8 micro g/ml) than many other bacteria (P. J. Petersen, N. V. Jacobus, W. J. Weiss, P. E. Sum, and R. T. Testa, Antimicrob. Agents Chemother. 43:738-744, 1999). To elucidate the mechanism of resistance to tigecycline, P. aeruginosa PAO1 strains defective in the MexAB-OprM and/or MexXY (OprM) efflux pumps were tested for susceptibility to tigecycline. Increased susceptibility to tigecycline (MIC, 0.5 to 1 ...[more]

PMID: 12604529

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Project description:Bacteria frequently encounter selection by both phages and antibiotics. However, our knowledge on the evolutionary interactions between phages and antibiotics are still limited. Here, we characterized a phage-resistant Pseudomonas aeruginosa variant PAO1-R1 that shows increased sensitivity to gentamicin and polymyxin B. Using whole genome sequencing, significant genome differences were observed between the reference P. aeruginosa PAO1 and PAO1-R1. Compared to PAO1, 64 gene-encoding proteins with nonsynonymous single nucleotide polymorphisms (SNPs) and 31 genes with insertion/deletion (indel) mutations were found in PAO1-R1. We observed a significant reduction in phage adsorption rate for both phage vB_Pae_QDWS and vB_Pae_W3 against PAO1-R1 and proposed that disruption of phage adsorption is likely the main cause for evolving resistance. Because the majority of spontaneous mutations are closely related to membrane components, alterations in the cell envelope may explain the antibiotic-sensitive phenotype of PAO1-R1. Collectively, we demonstrate that the evolution of phage resistance comes with fitness defects resulting in antibiotic sensitization. Our finding provides new insights into the evolutionary interactions between resistance to the phage and sensitivity to antibiotics, which may have implications for the future clinical use of steering in phage therapies. IMPORTANCE Bacteria frequently encounter the selection pressure from both antibiotics and lytic phages. Little is known about the evolutionary interactions between antibiotics and phages. Our study provides new insights into the trade-off mechanism between resistance to the phage and sensitivity to antibiotics. This evolutionary trade-off is not dependent on the outer membrane proteins (OMPs) of the multidrug efflux pumps. The disruption of phage adsorption that induced phage resistance and the changes in structure or composition of membranes are presumably one of the major causes for antibiotic sensitivity. Our finding may fill some gaps in the field of phage-host interplay and have implications for the future clinical use of steering in phage therapies.

Dataset Information

Efflux-mediated resistance to tigecycline (GAR-936) in Pseudomonas aeruginosa PAO1.

Publications

Efflux-mediated resistance to tigecycline (GAR-936) in Pseudomonas aeruginosa PAO1.

Similar Datasets

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