Sie befinden Sich nicht im Netzwerk der Universität Paderborn. Der Zugriff auf elektronische Ressourcen ist gegebenenfalls nur via VPN oder Shibboleth (DFN-AAI) möglich. mehr Informationen...
1007. Hypermutability in Clinical Strains of Klebsiella pneumoniae : Role of the V76G Mutation in MutH
Ist Teil von
Open forum infectious diseases, 2021-12, Vol.8 (Supplement_1), p.S594-S594
Erscheinungsjahr
2021
Link zum Volltext
Quelle
Free E-Journal (出版社公開部分のみ)
Beschreibungen/Notizen
Abstract
Background
Hypermutator (HM) bacteria exhibit high spontaneous mutation rates due to DNA mismatch repair (MMR) gene mutations, which may facilitate antibiotic resistance. HM is best described for chronic infections or colonization, in particular with P. aeruginosa. HM K. pneumoniae (KP) and carbapenem resistant Enterobacterales (CRE) are rarely studied.
Methods
Longitudinal isolates from 5 patients (pts) with long-term ST258 CRKP infections (median: 1.4 yr, 0.5-4.1 yr) underwent Illumina HiSeq whole genome sequencing. Strains from 1 pt were tested for HM and resistance. Mutant strains were created by complementation and CRISPR.
Results
In each pt, initial and recurrent isolates were genetically related (≤7 core genome (cg) SNP). In 1 pt, infection recurred 3.3 yrs after initial infection; baseline and recurrent (T0) isolates differed by 7-10 cgSNP. 4 ceftazidime-avibactam (CAZ) resistant isolates (T1-T4) were recovered ≥2 wks after treatment of T0 infection. Strains T1-T4 differed from T0 and each other by 109-214 and 58-137 cgSNP (Fig.1), respectively, and carried mutations in MMR genes (mutS -149∆C (∆pmutS); mutH V76G) and blaKPC3 (D179Y). T1-T4 mutations were enriched for genes involved in metabolism (adjusted p=1.46e-10), ABC transport (p=4.1e-7), 2-component systems (p=9.2e-5), signal transduction (p=6e-4), and transcription regulation (p=2.1e-4). mutS and mutH expression was 46-49% lower in T1-T4 than in T0. T1-T4 demonstrated rifampin mutational frequency >10-6.4, compared to < 10-7.3 for earlier strains. Upon passage in meropenem-vaborbactam (MV), colistin and gentamicin, T1-T4 developed resistance faster and higher MICs than T0 (Fig 2). MV resistance was associated with IS5 ompk36 promoter insertions or point, deletion or STOP mutations in ompK36 coding region. Complementation of T1-T4 with wild-type (WT) mutH restored phenotypes. Introduction of V76G to WT mutH in T0 established HM and in vitro passage resistance phenotypes.
SNP matrix of 11 clinical isolates from a single patient with recurrent KPC-Kp infections
The first 6 isolates were recovered within 6 months of transplant (Tinitial). The later 5 isolates were recovered ~40 months after intial GI colonization. Number of SNPs for each pariwise comparision on isolates are shown. Gray highlighted boxes shown SNP defferences between the 5 later strains.
Serial passages of 4 clinical isolates.
T1 and T4 harbored ΔpmutS. Ti=Tinitial (baseline) isolates
Conclusion
MMR mutations emerged in longitudinal CRKP, which conferred HM phenotypes and were associated with CAZ and other anti-CRE antibiotic resistance. mutH V76 is crucial in MMR. Long-term colonization or recurrent infections in face of antibiotic exposure might predispose CRKP strains to HM.
Disclosures
Cornelius J. Clancy, MD, Merck (Grant/Research Support)