Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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Gene expression data from Pseudomonas aeruginosa PAO1 and mutator (Î? mutS) evolved for 940 generations in LB with and without sub-inhibitory concentrations of ciprofloxacin (0.05Âµg/ml)

ABSTRACT: Gene expression of P. aerruginosa changes after short-term exposure to ciprofloxacin at sub-inhibitory concentrations but the effect of long-term exposure which select for the most fitted subpopulations is not known. We used microarrays to investigate the changes in gene expression of P.aeruginosa PAO1 and mutator (Î? mutS) after long-term evolution (94 daily passages) in LB in the presence and absence of ciprofloxacin Three different colonies from the ancestral populations of PAO1 and mutator (Î? mutS) as well as from the evolved populations (day 94) of each of the three lineages (A;B;C) in the presence or absence of ciprofloxacin at a concentration of 0.05 Âµg/ml were used for overnight cultures in LB and total RNA was extracted at OD600nm=1 and hybridized on P. aeruginosa Affymetrix chip.

ORGANISM(S): Pseudomonas aeruginosa

SUBMITTER: Oana Ciofu

PROVIDER: E-GEOD-78255 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:We compared the dynamics and mechanisms of resistance development to ceftazidime, meropenem, ciprofloxacin, and ceftolozane-tazobactam in wild-type (PAO1) and mutator (PAOMS, ∆mutS) P. aeruginosa. The strains were incubated for 24 h with 0.5 to 64× MICs of each antibiotic in triplicate experiments. The tubes from the highest antibiotic concentration showing growth were reinoculated in fresh medium containing concentrations up to 64× MIC for 7 consecutive days. The susceptibility profiles and resistance mechanisms were assessed in two isolated colonies from each step, antibiotic, and strain. Ceftolozane-tazobactam-resistant mutants were further characterized by whole-genome analysis through RNA sequencing (RNA-seq). The development of high-level resistance was fastest for ceftazidime, followed by meropenem and ciprofloxacin. None of the mutants selected with these antibiotics showed cross-resistance to ceftolozane-tazobactam. On the other hand, ceftolozane-tazobactam resistance development was much slower, and high-level resistance was observed for the mutator strain only. PAO1 derivatives that were moderately resistant (MICs, 4 to 8 ug/ml) to ceftolozane-tazobactam showed only 2 to 4 mutations, which determined global pleiotropic effects associated with a severe fitness cost. High-level-resistant (MICs, 32 to 128 ug/ml) PAOMS derivatives showed 45 to 53 mutations. Major changes in the global gene expression profiles were detected in all mutants, but only PAOMS mutants showed ampC overexpression, which was caused by dacB or ampR mutations. Moreover, all PAOMS mutants contained 1 to 4 mutations in the conserved residues of AmpC (F147L, Q157R, G183D, E247K, or V356I). Complementation studies revealed that these mutations greatly increased ceftolozane-tazobactam and ceftazidime MICs but reduced those of piperacillin-tazobactam and imipenem, compared to those in wild-type ampC. Therefore, the development of high-level resistance to ceftolozane-tazobactam appears to occur efficiently only in a P. aeruginosa mutator background, in which multiple mutations lead to overexpression and structural modifications of AmpC.

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Dataset Information

Gene expression data from Pseudomonas aeruginosa PAO1 and mutator (Î? mutS) evolved for 940 generations in LB with and without sub-inhibitory concentrations of ciprofloxacin (0.05Âµg/ml)

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