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Characterization of Pseudomonas aeruginosa resistance to ceftolozane-tazobactam due to ampC and/or ampD mutations observed during treatment using semi-mechanistic PKPD modeling
A double ampC (AmpC G183D ) and ampD (AmpD H157Y ) genes mutations have been identified by whole genome sequencing in a Pseudomonas aeruginosa (PaS) that became resistant (PaR) in a patient treated by ceftolozane/tazobactam (C/T). To precisely characterize the respective contributions of these mutat...
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Published in: | Antimicrobial agents and chemotherapy 2023-10, Vol.67 (10), p.e0048023-e0048023 |
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Main Authors: | , , , , , , , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | A double
ampC
(AmpC
G183D
) and
ampD
(AmpD
H157Y
) genes mutations have been identified by whole genome sequencing in a
Pseudomonas aeruginosa
(PaS) that became resistant (PaR) in a patient treated by ceftolozane/tazobactam (C/T). To precisely characterize the respective contributions of these mutations on the decreased susceptibility to C/T and on the parallel increased susceptibility to imipenem (IMI), mutants were generated by homologous recombination in PAO1 reference strain (PAO1- AmpC
G183D
, PAO1-AmpD
H157Y
, PAO1-AmpC
G183D
/AmpD
H157Y
) and in PaR (PaR-AmpC
PaS
/AmpD
PaS
). Sequential time-kill curve experiments were conducted on all strains and analyzed by semi-mechanistic PKPD modeling. A PKPD model with adaptation successfully described the data, allowing discrimination between initial and time-related (adaptive resistance) effects of mutations. With PAO1 and mutant-derived strains, initial EC
50
values increased by 1.4, 4.1, and 29-fold after AmpC
G183D
,
AmpD
H157Y
and AmpC
G183D
/AmpD
H157Y
mutations, respectively. EC
50
values were increased by 320, 12.4, and 55-fold at the end of the 2 nd experiment. EC
50
of PAO1-AmpC
G183D
/AmpD
H157Y
was higher than that of single mutants at any time of the experiments. Within the PaR clinical background, reversal of AmpC
G183D
, and AmpD
H157Y
mutations led to an important decrease of EC
50
value, from 80.5 mg/L to 6.77 mg/L for PaR and PaR-AmpC
PaS
/AmpD
PaS
, respectively. The effect of mutations on IMI susceptibility mainly showed that the AmpC
G183D
mutation prevented the emergence of adaptive resistance. The model successfully described the separate and combined effect of AmpC
G183D
and AmpD
H157Y
mutations against C/T and IMI, allowing discrimination and quantification of the initial and time-related effects of mutations. This method could be reproduced in clinical strains to decipher complex resistance mechanisms. |
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ISSN: | 0066-4804 1098-6596 |
DOI: | 10.1128/aac.00480-23 |