Ceftazidime resistance in Pseudomonas aeruginosa is multigenic and complex.
Pseudomonas aeruginosa causes a wide range of severe infections. Ceftazidime, a cephalosporin, is a key antibiotic for treating infections but a significant proportion of isolates are ceftazidime-resistant. The aim of this research was to identify mutations that contribute to resistance, and to quan...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
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Public Library of Science (PLoS)
2023-01-01
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| Series: | PLoS ONE |
| Online Access: | https://doi.org/10.1371/journal.pone.0285856 |
| _version_ | 1797802035039436800 |
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| author | Kay A Ramsay Attika Rehman Samuel T Wardell Lois W Martin Scott C Bell Wayne M Patrick Craig Winstanley Iain L Lamont |
| author_facet | Kay A Ramsay Attika Rehman Samuel T Wardell Lois W Martin Scott C Bell Wayne M Patrick Craig Winstanley Iain L Lamont |
| author_sort | Kay A Ramsay |
| collection | DOAJ |
| description | Pseudomonas aeruginosa causes a wide range of severe infections. Ceftazidime, a cephalosporin, is a key antibiotic for treating infections but a significant proportion of isolates are ceftazidime-resistant. The aim of this research was to identify mutations that contribute to resistance, and to quantify the impacts of individual mutations and mutation combinations. Thirty-five mutants with reduced susceptibility to ceftazidime were evolved from two antibiotic-sensitive P. aeruginosa reference strains PAO1 and PA14. Mutations were identified by whole genome sequencing. The evolved mutants tolerated ceftazidime at concentrations between 4 and 1000 times that of the parental bacteria, with most mutants being ceftazidime resistant (minimum inhibitory concentration [MIC] ≥ 32 mg/L). Many mutants were also resistant to meropenem, a carbapenem antibiotic. Twenty-eight genes were mutated in multiple mutants, with dacB and mpl being the most frequently mutated. Mutations in six key genes were engineered into the genome of strain PAO1 individually and in combinations. A dacB mutation by itself increased the ceftazidime MIC by 16-fold although the mutant bacteria remained ceftazidime sensitive (MIC < 32 mg/L). Mutations in ampC, mexR, nalC or nalD increased the MIC by 2- to 4-fold. The MIC of a dacB mutant was increased when combined with a mutation in ampC, rendering the bacteria resistant, whereas other mutation combinations did not increase the MIC above those of single mutants. To determine the clinical relevance of mutations identified through experimental evolution, 173 ceftazidime-resistant and 166 sensitive clinical isolates were analysed for the presence of sequence variants that likely alter function of resistance-associated genes. dacB and ampC sequence variants occur most frequently in both resistant and sensitive clinical isolates. Our findings quantify the individual and combinatorial effects of mutations in different genes on ceftazidime susceptibility and demonstrate that the genetic basis of ceftazidime resistance is complex and multifactorial. |
| first_indexed | 2024-03-13T04:59:37Z |
| format | Article |
| id | doaj.art-54bc854609b84c83a03edbd6886ce667 |
| institution | Directory Open Access Journal |
| issn | 1932-6203 |
| language | English |
| last_indexed | 2024-03-13T04:59:37Z |
| publishDate | 2023-01-01 |
| publisher | Public Library of Science (PLoS) |
| record_format | Article |
| series | PLoS ONE |
| spelling | doaj.art-54bc854609b84c83a03edbd6886ce6672023-06-17T05:31:24ZengPublic Library of Science (PLoS)PLoS ONE1932-62032023-01-01185e028585610.1371/journal.pone.0285856Ceftazidime resistance in Pseudomonas aeruginosa is multigenic and complex.Kay A RamsayAttika RehmanSamuel T WardellLois W MartinScott C BellWayne M PatrickCraig WinstanleyIain L LamontPseudomonas aeruginosa causes a wide range of severe infections. Ceftazidime, a cephalosporin, is a key antibiotic for treating infections but a significant proportion of isolates are ceftazidime-resistant. The aim of this research was to identify mutations that contribute to resistance, and to quantify the impacts of individual mutations and mutation combinations. Thirty-five mutants with reduced susceptibility to ceftazidime were evolved from two antibiotic-sensitive P. aeruginosa reference strains PAO1 and PA14. Mutations were identified by whole genome sequencing. The evolved mutants tolerated ceftazidime at concentrations between 4 and 1000 times that of the parental bacteria, with most mutants being ceftazidime resistant (minimum inhibitory concentration [MIC] ≥ 32 mg/L). Many mutants were also resistant to meropenem, a carbapenem antibiotic. Twenty-eight genes were mutated in multiple mutants, with dacB and mpl being the most frequently mutated. Mutations in six key genes were engineered into the genome of strain PAO1 individually and in combinations. A dacB mutation by itself increased the ceftazidime MIC by 16-fold although the mutant bacteria remained ceftazidime sensitive (MIC < 32 mg/L). Mutations in ampC, mexR, nalC or nalD increased the MIC by 2- to 4-fold. The MIC of a dacB mutant was increased when combined with a mutation in ampC, rendering the bacteria resistant, whereas other mutation combinations did not increase the MIC above those of single mutants. To determine the clinical relevance of mutations identified through experimental evolution, 173 ceftazidime-resistant and 166 sensitive clinical isolates were analysed for the presence of sequence variants that likely alter function of resistance-associated genes. dacB and ampC sequence variants occur most frequently in both resistant and sensitive clinical isolates. Our findings quantify the individual and combinatorial effects of mutations in different genes on ceftazidime susceptibility and demonstrate that the genetic basis of ceftazidime resistance is complex and multifactorial.https://doi.org/10.1371/journal.pone.0285856 |
| spellingShingle | Kay A Ramsay Attika Rehman Samuel T Wardell Lois W Martin Scott C Bell Wayne M Patrick Craig Winstanley Iain L Lamont Ceftazidime resistance in Pseudomonas aeruginosa is multigenic and complex. PLoS ONE |
| title | Ceftazidime resistance in Pseudomonas aeruginosa is multigenic and complex. |
| title_full | Ceftazidime resistance in Pseudomonas aeruginosa is multigenic and complex. |
| title_fullStr | Ceftazidime resistance in Pseudomonas aeruginosa is multigenic and complex. |
| title_full_unstemmed | Ceftazidime resistance in Pseudomonas aeruginosa is multigenic and complex. |
| title_short | Ceftazidime resistance in Pseudomonas aeruginosa is multigenic and complex. |
| title_sort | ceftazidime resistance in pseudomonas aeruginosa is multigenic and complex |
| url | https://doi.org/10.1371/journal.pone.0285856 |
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