A Novel Genome-Editing Platform for Drug-Resistant Acinetobacter baumannii Reveals an AdeR-Unrelated Tigecycline Resistance Mechanism.
Infections with the Gram-negative coccobacillus Acinetobacter baumannii are a major threat in hospital settings. The progressing emergence of multidrug-resistant clinical strains significantly reduces the treatment options for clinicians to fight A. baumannii infections. The current lack of robust methods to genetically manipulate drug-resistant A. baumannii isolates impedes research on resistance and virulence mechanisms in clinically relevant strains. In this study, we developed a highly efficient and versatile genome-editing platform enabling the markerless modification of the genome of A. baumannii clinical and laboratory strains, regardless of their resistance profiles. We applied this method for the deletion of AdeR, a transcription factor that regulates the expression of the AdeABC efflux pump in tigecycline-resistant A. baumannii, to evaluate its function as a putative drug target. Loss of adeR reduced the MIC90of tigecycline from 25 μg/ml in the parental strains to 3.1 μg/ml in the ΔadeR mutants, indicating its importance in the drug resistance phenotype. However, 60% of the clinical isolates remained nonsusceptible to tigecycline after adeR deletion. Evolution of artificial tigecycline resistance in two strains followed by whole-genome sequencing revealed loss-of-function mutations in trm, suggesting its role in an alternative AdeABC-independent tigecycline resistance mechanism. This finding was strengthened by the confirmation of trm disruption in the majority of the tigecycline-resistant clinical isolates. This study highlights the development and application of a powerful genome-editing platform for A. baumannii enabling future research on drug resistance and virulence pathways in clinically relevant strains.
BioVersys AG, Basel, Switzerland.|Biozentrum, University of Basel, Basel, Switzerland.
Vincent
V
Trebosc
BioVersys AG, Basel, Switzerland.
Sarah
S
Gartenmann
BioVersys AG, Basel, Switzerland.
Kevin
K
Royet
Biozentrum, University of Basel, Basel, Switzerland.
Pablo
P
Manfredi
BioVersys AG, Basel, Switzerland.
Marcus
M
Tötzl
BioVersys AG, Basel, Switzerland.
Birgit
B
Schellhorn
BioVersys AG, Basel, Switzerland.
Michel
M
Pieren
BioVersys AG, Basel, Switzerland.
Marcel
M
Tigges
BioVersys AG, Basel, Switzerland.
Sergio
S
Lociuro
BioVersys AG, Basel, Switzerland.
Peter C
PC
Sennhenn
BioVersys AG, Basel, Switzerland.
Marc
M
Gitzinger
Biozentrum, University of Basel, Basel, Switzerland.
Dirk
D
Bumann
BioVersys AG, Basel, Switzerland christian.kemmer@bioversys.com.
Christian
C
Kemmer
D018528:ATP-Binding Cassette Transporters / Q000235:genetics* / Q000378:metabolism; D000151:Acinetobacter Infections / Q000188:drug therapy* / Q000382:microbiology; D040981:Acinetobacter baumannii / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001483:Base Sequence; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D000072669:Gene Editing / Q000379:methods*; D055879:Gene Knock-In Techniques; D055786:Gene Knockout Techniques; D016680:Genome, Bacterial / Q000235:genetics; D008826:Microbial Sensitivity Tests; D008911:Minocycline / Q000031:analogs & derivatives* / Q000494:pharmacology; D017422:Sequence Analysis, DNA; D000078304:Tigecycline
D018528:ATP-Binding Cassette Transporters; D000900:Anti-Bacterial Agents; D000078304:Tigecycline; D008911:Minocycline
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