Abstract
BackgroundA carbapenem-resistant hypermucoviscous Klebsiella pneumoniae isolate was recovered from human sputum.MethodsWhole genome sequencing of this isolate was carried out to reveal its clonal background, antimicrobial resistance determinants and virulence factors. Virulence assays were performed using wax moth larvae. The transfer of blaNDM-5 between bacterial strains was tested using conjugation. 59 genome assemblies of ST29 K. pneumoniae and 230 IncX3 plasmids regardless of the carriage of resistance gene were employed for phylogenetic analysis, respectively.ResultsThe strain carried a virulence plasmid pVir-SCNJ1 bearing the virulence gene rmpA and exhibited a high virulence in wax moth. This hypervirulent strain belongs to sequence type 29 and carries blaNDM-5, which is located on a conjugative plasmid, designated pNDM5-SCNJ1, belonging to type IncX3. pNDM5-SCNJ1 was fully sequenced and shows high similarity with pNDM_MGR194, except some deletion inside the ISAba125 region. Phylogenetic analysis of IncX3 plasmids revealed that although blaNDM-5 can be evolved from blaNDM-1 via point mutations within some IncX3 plasmids, most of blaNDM-5-carrying IncX3 plasmids probably have acquired blaNDM-5 in multiple events.ConclusionsIn this study, we characterized a blaNDM-5-positive hypervirulent K. pneumoniae of sequence type 29 in China. Our results highlight the need for active surveillance on this lineage of carbapenem-resistant K. pneumoniae.
Highlights
Hypervirulent Klebsiella pneumoniae is a worldwide concern due to its capacity to cause lifethreatening, community-acquired infections in healthy individuals with high morbidity and mortality [1, 2]. hvKP strains are usually less resistant to most antimicrobials than classic K. pneumoniae [3], but the increasingYuan et al Antimicrobial Resistance and Infection Control (2019) 8:140 group of serine-lactamases), followed by IMP, and they belong to the widely distributed sequence type (ST) 11 [2, 8] and several other STs, e.g., ST25, ST65 [6] and ST36 [4]
Antimicrobial susceptibility test showed that the K. pneumoniae SCNJ1 strain was resistant to imipenem (MIC, > 256 μg/ml) and meropenem (MIC, > 256 μg/ml) cefepime (MIC, 16 μg/ml), piperacillin-tazobactam (MIC, ≥ 128 μg/ ml), ampicillin (MIC, ≥ 32 μg/ml), ampicillin/sulbactam (MIC, ≥ 32 μg/ml), cefotetan (MIC, ≥ 64 μg/ml), ceftriaxone (MIC, ≥ 64 μg/ml), cefazolin (MIC, ≥ 64 μg/ml), nitrofurantoin (MIC,128 μg/ml) and ceftazidime (MIC, ≥ 64 μg/ml), but was susceptible to colistin (MIC, 2 μg/ml), tobramycin (MIC, ≤ 1 μg/ml), ciprofloxacin (MIC, ≤ 0.25 μg/ml), trimethoprim/sulfamethoxazole (MIC, ≤ 20 μg/ml), aztreonam (MIC, ≤ 1 μg/ml), amikacin (MIC, ≤2 μg/ml), gentamicin (MIC, ≤1 μg/ml) and levofloxacin (MIC, ≤ 0.25 μg/ml)
PCR and sequencing showed that blaNDM-5 was the only carbapenemase-encoding gene carried by the strain SCNJ1
Summary
Whole genome sequencing of this isolate was carried out to reveal its clonal background, antimicrobial resistance determinants and virulence factors. Virulence assays were performed using wax moth larvae. The transfer of blaNDM-5 between bacterial strains was tested using conjugation. 59 genome assemblies of ST29 K. pneumoniae and 230 IncX3 plasmids regardless of the carriage of resistance gene were employed for phylogenetic analysis, respectively The transfer of blaNDM-5 between bacterial strains was tested using conjugation. 59 genome assemblies of ST29 K. pneumoniae and 230 IncX3 plasmids regardless of the carriage of resistance gene were employed for phylogenetic analysis, respectively
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