BKC-2, a New BKC Variant Detected in MCR-9.1-Producing Enterobacter hormaechei subsp.
            <i>xiangfangensis</i>

Martins, Willames M. B. S.; Martins, Elisabeth Nogueira; Andrade, Letícia Kellen de; Farzana, Refath; Walsh, Timothy R.; Toleman, Mark A.; Nogueira, Mara Corrêa Lelles; Gales, Ana Cristina

doi:10.1128/aac.01193-20

Cited by 9 publications

(3 citation statements)

References 17 publications

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“…One of the factors is a two-component regulatory system encoded by qseC/qseB downstream of mcr-9, as reported in an E. coli isolate harboring mcr-9 (21). Four other studies (25,(32)(33)(34), however, reported that mcr-9-positive isolates carrying qseC/qseB were susceptible to colistin, including 10 isolates of Salmonella and E. coli (32), and one isolate each of E. xiangfangensis (25), Citrobacter telavivum (33), and Enterobacter hormaechei (34). In contrast, four additional studies (35)(36)(37)(38) reported that mcr-9-positive isolates without qseC/qseB were resistant to colistin, including one isolate each of Salmonella Newport (35), Enterobacter kobei (36,37), Enterobacter roggenkampii (38).…”

Section: Resultsmentioning

confidence: 82%

Modified Drug-Susceptibility Testing and Screening Culture Agar for Colistin-Susceptible Enterobacteriaceae Isolates Harboring a Mobilized Colistin Resistance Gene mcr-9

et al. 2022

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Three isolates of the Enterobacter cloacae complex harboring mcr-9 , a member of the colistin resistance mcr gene family encoded on plasmids, were susceptible to colistin, with MICs of 0.125 to 0.5 μg/mL in standard broth microdilution (BMD) tests using cation-adjusted Mueller-Hinton broth (CA-MHB) in accordance with European Committee on Antimicrobial Susceptibility Testing guidelines. In contrast, their MICs for colistin were significantly higher (4 to 128 μg/mL) when BMD tests were performed using brain-heart infusion (BHI) medium, Luria-Bertani (LB) broth, tryptic soy broth (TSB), or CA-MHB supplemented with casein, tryptonen or peptone.

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Section: Resultsmentioning

confidence: 82%

Modified Drug-Susceptibility Testing and Screening Culture Agar for Colistin-Susceptible Enterobacteriaceae Isolates Harboring a Mobilized Colistin Resistance Gene mcr-9

et al. 2022

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“…Multiple Enterobacterial species, including Salmonella ( 45 ), E. coli ( 45 ), E. asburiae ( 50 ), Citrobacter telavivum ( 51 ), and E. hormaechei ( 52 ) with the so-called qseBC genes, have been reported to exhibit colistin-susceptible phenotypes. In contrast, some other studies also found that lack of such a tandem system in certain bacterial species was associated with colistin-resistant phenotypes, as with E. roggenkampii ( 34 ), E. cloacae complex ( 48 ), and S .…”

Section: Discussionmentioning

confidence: 99%

Emergence of colistin-resistant Enterobacter cloacae and Raoultella ornithinolytica carrying the phosphoethanolamine transferase gene, mcr-9 , derived from vegetables in Japan

Xedzro,

Shimamoto,

et al. 2023

Microbiol Spectr

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Colistin, a last-line antimicrobial agent, is recommended for the treatment of severe infections caused by multidrug-resistant (MDR) microorganisms. However, reports on plasmid-mediated mobilized colistin resistance ( mcr ) genes have prompted the importance of routine colistin resistance surveillance. Herein, we report the emergence of Enterobacter cloacae CST17-2 and Raoultella ornithinolytica CST129-1 carrying an mcr-9.1 gene in vegetables from Japan. A total of 308 colistin-resistant isolates were retrieved from 200 fresh vegetables in Hiroshima Prefecture, Japan. PCR detection of mcr-1 to mcr-9 was conducted. While none of the isolates detected positive for mcr-1 to mcr-8 genes, we found two (0.65%) positive strains, E. cloacae CST17-2 and R. ornithinolytica CST129-1, that harbored mcr-9.1 allele. These isolates were subjected to phenotypic susceptibility testing, whole-genome sequencing (WGS), PCR-based replicon typing, and conjugation experiment. We found that both isolates had high colistin resistance [minimum inhibitory concentration (MIC) 16 or >64 µg/mL] and showed MDR phenotypes. WGS of both isolates revealed mcr-9 on a plasmid of the IncHI2/HI2A backbone. The mcr-9 -bearing plasmid, pCST17-2_1, was self-transferable, although the pCST129-1_1 plasmid was not. Despite being colistin-resistant, the so-called two-component regulatory operon, qseBC , which induces polymyxin resistance, was absent from the genetic arrangements downstream of mcr-9 in R. ornithinolytica CST129-1. Nonetheless, a conjugation experiment demonstrated that mcr-9 in a Raoultella -type background is capable of mediating colistin resistance. In silico genomic analysis and comparison revealed distinct genetic structures surrounding mcr-9 , especially in the downstream vicinities. The E. cloacae CST17-2 strain is of sequence-type ST738, a sequence type that has emerged in mcr-9.1 -containing E. cloacae . Remarkably, we report the first mcr-9 -carrying colistin-resistant Enterobacteriaceae isolated from Japanese vegetables, which is a grave public health concern. Our findings highlight the importance of strict epidemiological monitoring to track and/or prevent further dissemination of mcr homologs across the vegetable industry. IMPORTANCE Plasmid-mediated mobile colistin-resistance genes have been recognized as a global threat because they jeopardize the efficacy of colistin in therapeutic practice. Here, we described the genetic features of two mcr-9.1 -carrying Gram-negative bacteria with a colistin-resistant phenotype derived from vegetables in Japan. The colistin-resistant mcr-9.1 , which has never been detected in vegetables, was located on a large plasmid in Enterobacter cloacae CST17-2 and Raoultella ornithinolytica CST129-1, suggesting a high chance of horizontal gene transfer. To the best of our knowledge, this is the first report of mcr-9 in R. ornithinolytica . This study indicates that fresh vegetables might be a potential source for the transmission of mcr-9 genes encoding resistance to frontline (colistin) and clinically relevant antimicrobials. The study also provides additional consideration for colistin use and the relevance of routine surveillance in epidemiological perspective to curb the continuous spread of mcr alleles.

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“…que confere resistência às polimixinas. [154][155] O gene mcr-9 estava abrigado em um plasmídeo IncHI2/IncHI2A em seu ambiente genético é composto pelo gene rcnR, que codifica um repressor do gene rcnA, que é uma bomba de efluxo de níquel e cobalto além de pcoE e pcoS que são envolvidos em resistência ao cobre. A presença destes genes sugere que esta linhagem também seja resistente a estes metais.…”

Section: O Impacto Da Presença Do Plasmídeo Carreando Blakpc Em E Col...unclassified

Plasmídeos e ambientes genéticos envolvidos na transferência do gene >i<bl>/i<>i<a>/i<>sub<KPC>/sub< em bactérias gram-negativas de origem clínica

Boralli

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BKC-2, a New BKC Variant Detected in MCR-9.1-Producing Enterobacter hormaechei subsp. xiangfangensis

Cited by 9 publications

References 17 publications

Modified Drug-Susceptibility Testing and Screening Culture Agar for Colistin-Susceptible Enterobacteriaceae Isolates Harboring a Mobilized Colistin Resistance Gene mcr-9

Modified Drug-Susceptibility Testing and Screening Culture Agar for Colistin-Susceptible Enterobacteriaceae Isolates Harboring a Mobilized Colistin Resistance Gene mcr-9

Emergence of colistin-resistant Enterobacter cloacae and Raoultella ornithinolytica carrying the phosphoethanolamine transferase gene, mcr-9 , derived from vegetables in Japan

Plasmídeos e ambientes genéticos envolvidos na transferência do gene >i<bl>/i<>i<a>/i<>sub<KPC>/sub< em bactérias gram-negativas de origem clínica

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