Development of Tigecycline Resistance in Carbapenemase-Producing Klebsiella pneumoniae Sequence Type 147 via AcrAB Overproduction Mediated by Replacement of the ramA Promoter
Annals of Laboratory Medicine
;
: 15-20, 2020.
Article
Dans Anglais
| WPRIM
| ID: wpr-762460
ABSTRACT
BACKGROUND:
Carbapenem-resistant K. pneumoniae 2297, isolated from a patient treated with tigecycline for pneumonia, developed tigecycline resistance, in contrast to carbapenem-resistant isolate 1215, which was collected four months prior to the 2297 isolate. Mechanisms underlying tigecycline resistance were elucidated for the clinical isolates.METHODS:
The tigecycline minimum inhibitory concentration (MIC) was determined using the broth microdilution method, with or without phenylalanine-arginine β-naphthylamide (PABN), and whole-genome sequencing was carried out by single-molecule real-time sequencing. The expression levels of the genes acrA, oqxA, ramA, rarA, and rpoB were determined by reverse-transcription quantitative PCR.RESULTS:
Both isolates presented identical antibiograms, except for tigecycline, which showed an MIC of 0.5 mg/L in 1215 and 2 mg/L in 2297. The addition of PABN to tigecycline-resistant 2297 caused a four-fold decrease in the tigecycline MIC to 0.5 mg/L, although acrA expression (encoding the AcrAB efflux pump) was upregulated by 2.5 fold and ramA expression (encoding the pump activator RamA) was upregulated by 1.4 fold. We identified a 6,096-bp fragment insertion flanking direct TATAT repeats that disrupted the romA gene located upstream of ramA in the chromosome of K. pneumoniae 2297; the insertion led the ramA gene promoter replacement resulting in stronger activation of the gene.CONCLUSIONS:
The K. pneumoniae isolate developed tigecycline resistance during tigecycline treatment. It was related to the overexpression of the AcrAB resistance-nodulation-cell division efflux system due to promoter replacement.
Texte intégral:
Disponible
Indice:
WPRIM (Pacifique occidental)
Sujet Principal:
Pneumopathie infectieuse
/
Rome
/
Tests de sensibilité microbienne
/
Réaction de polymérisation en chaîne
/
Klebsiella
/
Klebsiella pneumoniae
/
Méthodes
Limites du sujet:
Humains
Pays comme sujet:
Europe
langue:
Anglais
Texte intégral:
Annals of Laboratory Medicine
Année:
2020
Type:
Article
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