AUTHOR=Ali Md Roushan , Yang Yu , Dai Yuanyuan , Lu Huaiwei , He Zhien , Li Yujie , Sun Baolin 

TITLE=Prevalence of multidrug-resistant hypervirulent Klebsiella pneumoniae without defined hypervirulent biomarkers in Anhui, China: a new dimension of hypervirulence

JOURNAL=Frontiers in Microbiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2023.1247091

DOI=10.3389/fmicb.2023.1247091

ISSN=1664-302X

ABSTRACT=<p><italic>Klebsiella pneumoniae</italic> is an opportunistic pathogen that mainly causes nosocomial infections and hospital-associated pneumonia in elderly and immunocompromised people. However, multidrug-resistant hypervirulent <italic>K. pneumoniae</italic> (MDR-hvKp) has emerged recently as a serious threat to global health that can infect both immunocompromised and healthy individuals. It is scientifically established that plasmid-mediated regulator of mucoid phenotype genes (<italic>rmpA</italic> and <italic>rmpA2</italic>) and other virulence factors (aerobactin and salmochelin) are mainly responsible for this phenotype. In this study, we collected 23 MDR-hvKp isolates and performed molecular typing, whole genome sequencing, comparative genomic analysis, and phenotypic experiments, including the <italic>Galleria mellonella</italic> infection model, to reveal its genetic and phenotypic features. Meanwhile, we discovered two MDR-hvKp isolates (22122315 and 22091569) that showed a wide range of hypervirulence and hypermucoviscosity without <italic>rmpA</italic> and <italic>rmpA2</italic> and any virulence factors. In phenotypic experiments, isolate 22122315 showed the highest hypervirulence (infection model) with significant mucoviscosity, and conversely, isolate 22091569 exhibited the highest mucoviscosity (string test) with higher virulence compared to control. These two isolates carried carbapenemase (<italic>bla</italic><sub>KPC − 2</sub>), β-lactamase (<italic>bla</italic><sub>OXA − 1</sub>, <italic>bla</italic><sub>TEM − 1B</sub>), extended-spectrum β-lactamase (ESBL) genes (<italic>bla</italic><sub>CTX − M − 15</sub>, <italic>bla</italic><sub>SHV − 106</sub>), outer membrane protein-coding genes (<italic>ompA</italic>), fimbriae encoding genes (<italic>ecpABCDER</italic>), and enterobactin coding genes (<italic>entAB</italic>, <italic>fepC</italic>). In addition, single nucleotide polymorphism analysis indicated that both isolates, 22122315 and 22091569, were found to have novel mutations in loci <italic>FEBNDAKP_03184</italic> (c. 2084A &gt; C, p. Asn695Thr), and <italic>EOFMAFIB_02276</italic> (c. 1930C &gt; A, p. Pro644Thr), respectively. Finally, NCBI blast analysis suggested these mutations are located in the <italic>wzc</italic> of the capsule polysaccharide (<italic>cps</italic>) region and are responsible for putative tyrosine kinase. This study would be a strong reference for enhancing the current understanding of identifying the MDR-hvKp isolates that lacked both mucoid regulators and virulence factors.</p>