Polymyxin Resistance in Clinical Isolates of K. pneumoniae in Brazil: Update on Molecular Mechanisms, Clonal Dissemination and Relationship With KPC-Producing Strains

Abstract

In Brazil, the production of KPC-type carbapenemases in Enterobacteriales is endemic, leading to widespread use of polymyxins. In the present study, 502 Klebsiella pneumoniae isolates were evaluated for resistance to polymyxins, their genetic determinants and clonality, in addition to the presence of carbapenem resistance genes and evaluation of antimicrobial resistance. Resistance to colistin (polymyxin E) was evaluated through initial selection on EMB agar containing 4% colistin sulfate, followed by Minimal Inhibitory Concentration (MIC) determination by broth microdilution. The susceptibility to 17 antimicrobials was assessed by disk diffusion. The presence of blaKPC, blaNDM and blaOXA-48-like carbapenemases was investigated by phenotypic methods and conventional PCR. Molecular typing was performed by PFGE and MLST. Allelic variants of the mcr gene were screened by PCR and chromosomal mutations in the pmrA, pmrB, phoP, phoQ and mgrB genes were investigated by sequencing. Our work showed a colistin resistance frequency of 29.5% (n = 148/502) in K. pneumoniae isolates. Colistin MICs from 4 to >128 µg/mL were identified (MIC50 = 64 µg/mL; MIC90 >128 µg/mL). All isolates were considered MDR, with the lowest resistance rates observed for amikacin (34.4%), and 19.6% of the isolates were resistant to all tested antimicrobials. The blaKPC gene was identified in 77% of the isolates, in consonance with the high rate of resistance to polymyxins related to its use as a therapeutic alternative. Through XbaI-PFGE, 51 pulsotypes were identified. MLST showed 21 STs, with ST437, ST258 and ST11 (CC11) being the most prevalent, and two new STs were determined: ST4868 and ST4869. The mcr-1 gene was identified in 3 K. pneumoniae isolates. Missense mutations in chromosomal genes were identified, as well as insertion sequences in mgrB. Furthermore, the identification of chromosomal mutations in K. pneumoniae isolates belonging from CC11 ensures its success as a high-risk epidemic clone in Brazil and worldwide.

Analyzing resistome in soil and Human gut: a study on the characterization and risk evaluation of antimicrobial peptide resistance

“…When cross-resistance emerges between AMPs and human defensins, it can lead to compromised immune function and challenging-to-manage infections ( Samuelsen et al, 2005 ; Habets and Brockhurst, 2012 ; Fleitas and Franco, 2016 ). Our research aligns with numerous other studies that underscore the widespread occurrence of cross-resistance among AMPs ( Pränting and Andersson, 2010 ; Forsberg et al, 2012 ; Blanco et al, 2020 ; Conceição-Neto et al, 2022 ). Many of the resistance mechanisms associated with AMPs are linked to bacterial nutrient acquisition and the formation of biofilm matrices.…”

“…A small number of AMP resistance genes that closely resemble known antibiotic resistance genes were identified through our comparison with the Comprehensive Antimicrobial Resistance Database (CARD), indicating the potential for cross-resistance between AMPs and antibiotics. Cross-resistance involves antibiotics such as aminoglycosides (the most common), cephalosporins, tetracyclines, macrolides, and others, as reported in previous studies ( Kubicek-Sutherland et al, 2017 ; Blanco et al, 2020 ; Conceição-Neto et al, 2022 ). The clinical treatment options are undeniably narrowed by this limitation.…”

Ompk36 disruption and expression of down-regulated blaKPC-2 in Klebsiella pneumoniae clinical isolates carbapenem resistant

“…Resistance to carbapenems in this species does not occur naturally and is mainly related to the acquisition of βlactamases, the most common of which are carbapenemases, especially Klebsiella pneumoniae carbapenemase (KPC). KPCproducing strains of K. pneumoniae, originally isolated in the USA, have spread and reached a wide geographical distribution (Villegas et al, 2006;Gupta et al, 2011;Nordmann, et al, 2012;Conceição-Neto et al, 2022).…”

First Report of Potentially Pathogenic Klebsiella pneumoniae from Serotype K2 in Mollusk Tegillarca granosa and Genetic Diversity of Klebsiella pneumoniae in 14 Species of Edible Aquatic Animals

“…A number of K. pneumoniae strains have been isolated from clinical samples and characterized [ 24 , 25 ]. However, to the best of our knowledge, the current literature in the prevalence and genetic diversity of K. pneumoniae in aquatic animals is little [ 26 ].…”