Dataset Information

In vitro selection of aztreonam/avibactam resistance in dual-carbapenemase-producing Klebsiella pneumoniae.

ABSTRACT: OBJECTIVES:To examine the in vitro selection of aztreonam/avibactam resistance among MBL-producing Klebsiella pneumoniae and to understand the mechanism of increased resistance. METHODS:The MICs of aztreonam were determined with and without avibactam (4?mg/L) using a broth microdilution method. Single-step and multi-step mutant selection was conducted on five MBL-producing K. pneumoniae strains, including two dual carbapenemase producers. Genomic sequencing and gene cloning were performed to investigate the mechanism of increased resistance. RESULTS:We examined the MICs for 68 MBL-producing K. pneumoniae isolates, including 13 dual carbapenemase producers. Compared with aztreonam alone, the addition of avibactam (4?mg/L) reduced the MICs for all isolates by >128-fold, with MIC50 and MIC90 values of 0.25 and 1?mg/L, respectively. One NDM-1-, OXA-48-, CTX-M-15- and CMY-16-positive ST101 K. pneumoniae strain was selected to be resistant to aztreonam/avibactam, with a >16-fold increase in MIC (>128?mg/L). WGS revealed that the resistant mutants lost the blaNDM-1 gene, but acquired amino acid substitutions in CMY-16 (Tyr150Ser and Asn346His). Construction of blaCMY-16 mutants confirmed that the substitutions (Tyr150Ser and Asn346His) were primarily responsible for the decreased susceptibility to aztreonam/avibactam. In addition, transfer of blaCMY-16 mutant (Tyr150Ser and Asn346His) plasmid constructs into certain clinical carbapenemase-producing isolates demonstrated >64-fold increased MICs of aztreonam/avibactam and aztreonam/avibactam/ceftazidime. CONCLUSIONS:Aztreonam in combination with avibactam showed potent in vitro activity against MBL-producing K. pneumoniae. However, our study suggested the likelihood of aztreonam/avibactam resistance among MBL- and AmpC-co-producing strains and clinical practice should beware of the possibility of the emerging resistance.

SUBMITTER: Niu S

PROVIDER: S-EPMC7021086 | biostudies-literature | 2020 Mar

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

Project description:Klebsiella pneumoniae carbapenemase (KPC)-producing Pseudomonas aeruginosa (KPC-PA) has been reported sporadically. However, epidemiological and antimicrobial susceptibility data specific for KPC-PA are lacking. We collected 374 carbapenem-resistant P. aeruginosa (CRPA) isolates from seven hospitals in China from June 2016 to February 2019 and identified the blaKPC-2 gene in 40.4% (n = 151/374) of the isolates. Approximately one-half of all KPC-PA isolates (n = 76/151; 50.3%) were resistant to ceftazidime-avibactam (CAZ-AVI). Combining Kraken2 taxonomy identification and Nanopore sequencing, we identified eight plasmid types, five of which carried blaKPC-2, and 13 combination patterns of these plasmid types. In addition, we identified IS26-ΔTn6296 and Tn1403-like-ΔTn6296 as the two mobile genetic elements that mediated blaKPC-2 transmission. blaKPC-2 plasmid curing in 28 strains restored CAZ-AVI susceptibility, suggesting that blaKPC-2 was the mediator of CAZ-AVI resistance. Furthermore, the blaKPC-2 copy number was found to correlate with KPC expression and, therefore, CAZ-AVI resistance. Taken together, our results suggest that KPC-PA is becoming a clinical threat and that using CAZ-AVI to treat this specific pathogen should be done with caution. IMPORTANCE Previous research has reported several cases of KPC-PA strains and three KPC-encoding P. aeruginosa plasmid types in China. However, the prevalence and clinical significance of KPC-PA are not available. In addition, the susceptibility of the strains to CAZ-AVI remains unknown. Samples in this study were collected from seven tertiary hospitals prior to CAZ-AVI clinical approval in China. Therefore, our results represent a retrospective study establishing the baseline efficacy of the novel β-lactam/β-lactamase combination agent for treating KPC-PA infections. The observed correlation between the blaKPC copy number and CAZ-AVI resistance suggests that close monitoring of the susceptibility of the strain during treatment is required. It would also be beneficial to screen for the blaKPC gene in CRPA strains for antimicrobial surveillance purposes.

Project description:We describe in vivo evolution of carbapenem and ceftazidime-avibactam resistance by analyzing four longitudinal Klebsiella pneumoniae clinical isolates from a patient with pneumonia following antimicrobial treatment. The patient had fever, cough associated with expectoration, and new infiltration was found on the chest CT. Antimicrobial susceptibility was determined, and whole genome sequencing (WGS) was performed to investigate its dynamic change of resistance phenotype. Population analysis profile was performed to investigate the population of Klebsiella pneumoniae. The infection started with a KPC-2-producing K. pneumoniae (ZRKP01, ceftazidime-avibactam-S/carbapenem-R). Then, after ceftazidime-avibactam treatment, the strain switched to D179Y mutant that is KPC-33 (ZRKP02, ceftazidime-avibactam-R/carbapenem-S), which restored carbapenem susceptibility. However, the restored carbapenem susceptibility in vivo was not stable and the subsequent use of imipenem against KPC-33-producing K. pneumoniae infection resulted in a reversion of KPC-2 producers (ZRKP03 and ZRKP04, ceftazidime-avibactam-S/carbapenem-R). Genetic analysis demonstrated that all four K. pneumoniae isolates belonged to sequence type 11and had identical capsular polysaccharide (KL47), identical porin genes, and same plasmid replicon types. Phylogenetic analysis indicated that four K. pneumoniae isolates showed a high degree of relatedness. Single nucleotide polymorphisms analysis indicated that the number of mutations observed in the KPC-33 isolate was more than in the wild-type KPC-2 isolates and the four KPC-Kp isolates evolved from a longitudinal evolution of K. pneumoniae harboring bla KPC-2 gene. This is the first report to observe the in vivo evolution of wild-type KPC-2 to KPC-33 and then the reversion to its original wild-type KPC-2. Through WGS, we demonstrated the role of selective pressure of antibiotic in the mutation and reversion of bla KPC genes, which leading to the dynamic change of KPC enzymes and the dynamic emergence of resistance to ceftazidime-avibactam and carbapenems. Statement: Recently, studies reported the emergence of ceftazidime-avibactam-resistant strains. The KPC mutations mediating ceftazidime-avibactam resistance are generally associated with the restoration of carbapenem susceptibility. However, clinical significance of this observation is unclear. In this manuscript, we demonstrate the role of selective pressure of antibiotic in the mutation and reversion of bla KPC genes, which leading to the dynamic change of KPC enzymes and the dynamic emergence of resistance to ceftazidime-avibactam and carbapenems. To the best of our knowledge, this is the first report to observe the in vivo evolution of wild-type KPC-2 to KPC-33 and then the reversion to its original wild-type KPC-2. It should be noted that understanding the clinical significance of this observation is of critical importance, and reversion to carbapenem susceptibility would not imply a potential role for carbapenems monotherapy. We hope our study will draw attention to clinicians, so that this agent can be used most effectively for the longest period of time.

Dataset Information

In vitro selection of aztreonam/avibactam resistance in dual-carbapenemase-producing Klebsiella pneumoniae.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets