Characterization of blaKPC-2 and blaNDM-1 Plasmids of a K. pneumoniae ST11 Outbreak Clone

Camila Maria Dos Santos Boralli; Julian Andres Paganini; Rodrigo Silva Meneses; Camila Pacheco Silveira Martins da Mata; Edna Marilea Meireles Leite; Anita C Schürch; Fernanda L Paganelli; Rob J L Willems; Ilana Lopes Baratella Cunha Camargo

doi:10.3390/antibiotics12050926

Characterization of bla_KPC-2 and bla_NDM-1 Plasmids of a K. pneumoniae ST11 Outbreak Clone

Antibiotics (Basel). 2023 May 18;12(5):926. doi: 10.3390/antibiotics12050926.

Authors

Camila Maria Dos Santos Boralli¹, Julian Andres Paganini², Rodrigo Silva Meneses², Camila Pacheco Silveira Martins da Mata³, Edna Marilea Meireles Leite³, Anita C Schürch², Fernanda L Paganelli², Rob J L Willems², Ilana Lopes Baratella Cunha Camargo¹

Affiliations

¹ Laboratory of Molecular Epidemiology and Microbiology, Department of Physics and Interdisciplinary Science, São Carlos Institute of Physics, University of São Paulo, São Carlos 13563-120, Brazil.
² University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands.
³ Risoleta Tolentino Neves Hospital, Belo Horizonte 31744-012, Brazil.

Abstract

The most common resistance mechanism to carbapenems is the production of carbapenemases. In 2021, the Pan American Health Organization warned of the emergence and increase in new carbapenemase combinations in Enterobacterales in Latin America. In this study, we characterized four Klebsiella pneumoniae isolates harboring bla_KPC and bla_NDM from an outbreak during the COVID-19 pandemic in a Brazilian hospital. We assessed their plasmids' transference ability, fitness effects, and relative copy number in different hosts. The K. pneumoniae BHKPC93 and BHKPC104 strains were selected for whole genome sequencing (WGS) based on their pulsed-field gel electrophoresis profile. The WGS revealed that both isolates belong to ST11, and 20 resistance genes were identified in each isolate, including bla_KPC-2 and bla_NDM-1. The bla_KPC gene was present on a ~56 Kbp IncN plasmid and the bla_NDM-1 gene on a ~102 Kbp IncC plasmid, along with five other resistance genes. Although the bla_NDM plasmid contained genes for conjugational transfer, only the bla_KPC plasmid conjugated to E. coli J53, without apparent fitness effects. The minimum inhibitory concentrations (MICs) of meropenem/imipenem against BHKPC93 and BHKPC104 were 128/64 and 256/128 mg/L, respectively. Although the meropenem and imipenem MICs against E. coli J53 transconjugants carrying the bla_KPC gene were 2 mg/L, this was a substantial increment in the MIC relative to the original J53 strain. The bla_KPC plasmid copy number was higher in K. pneumoniae BHKPC93 and BHKPC104 than in E. coli and higher than that of the bla_NDM plasmids. In conclusion, two ST11 K. pneumoniae isolates that were part of a hospital outbreak co-harbored bla_KPC-2 and bla_NDM-1. The bla_KPC-harboring IncN plasmid has been circulating in this hospital since at least 2015, and its high copy number might have contributed to the conjugative transfer of this particular plasmid to an E. coli host. The observation that the bla_KPC-containing plasmid had a lower copy number in this E. coli strain may explain why this plasmid did not confer phenotypic resistance against meropenem and imipenem.

Keywords: Klebsiella pneumoniae; blaKPC; blaNDM; conjugation rate; plasmid; plasmid copy number.

Abstract

Grants and funding