Title |
Comparative analysis of the colistin resistance-regulating gene cluster in Klebsiella species |
Author |
Sun Ju Kim1, Hongbaek Cho2*, and Kwan Soo Ko1* |
Address |
1Department of Microbiology, Sungkyunkwan University School of Medicine, Suwon 16419, Republic of Korea, 2Department of Biological Sciences, Sungkyunkwan University, Suwon 16419, Republic of Korea |
Bibliography |
Journal of Microbiology, 60(5),461–468, 2022,
|
DOI |
10.1007/s12275-022-1640-z
|
Key Words |
Klebsiella, crrAB, kexD, colistin resistance |
Abstract |
CrrAB two-component regulatory system is associated with
colistin resistance in Klebsiella pneumoniae. Recently, some
K. pneumoniae isolates lacking crrAB genes have been identified.
In this study, we investigated the distribution and structural
variation of the crrBAC-kexD cluster. To evaluate the
structural variation of the crrBAC-kexD cluster, we explored
59 clinical K. pneumoniae isolates from Korea, and 508 whole
genomes of K. pneumoniae and other strains of Klebsiella
sp. Significant structural variations in crrBAC-kexD and its
surrounding regions were identified among K. pneumoniae
genomes. Within the genus Klebsiella, the cluster was identified
only in K. pneumoniae, K. variicola, and K. quasipneumoniae,
which form the K. pneumoniae complex. Among the
304 available K. pneumoniae genomes, an intact crrBAC-kexD
cluster was identified in 178 isolates (58.6%), while the cluster
was absent in 90 isolates (29.6%). Partial deletions within
the cluster were identified in 22 genomes (7.2%). The most
diverse structural patterns of the crrBAC-kexD cluster were
observed in ST11 strains. Some clades lacked the crrBAC-kexD
cluster. The crrBAC-kexD cluster was identified in the genomes
of other bacterial species, including Citrobacter freundii and
Enterobacter ludwigii. The crrBAC-kexD cluster is proposed
to have been acquired by the ancestor of the K. pneumoniae
complex from other bacterial species and the cluster may have
been lost and re-acquired repeatedly in K. pneumoniae strains
according to the phylogenetic analysis. The dynamic evolution
of the crrBAC-kexD cluster suggests that it may have other
roles, in addition to colistin resistance, in bacterial physiology. |