Emergence of carbapenem-resistant Pseudomonas alcaligenes and Pseudomonas paralcaligenes clinical isolates with plasmids harbouring bla IMP-1 in Japan

<jats:p> <jats:bold>Introduction.</jats:bold> The emergence of carbapenem-resistant <jats:italic> <jats:named-content content-type="genus"> <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://doi.org/10.1601/nm.2552" xlink:type="simple">Pseudomonas</jats:ext-link> </jats:named-content> </jats:italic> species producing metallo-β-lactamase (MBL) has become a serious medical problem worldwide. IMP-type MBL was firstly detected in 1991 in Japan. Since then, it has become one of the most prevalent types of MBLs.</jats:p> <jats:p> <jats:bold>Hypothesis/Gap statement.</jats:bold> Avirulent species of <jats:italic> <jats:named-content content-type="genus"> <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://doi.org/10.1601/nm.2552" xlink:type="simple">Pseudomonas</jats:ext-link> </jats:named-content> </jats:italic>, such as <jats:italic> <jats:named-content content-type="species"> <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://doi.org/10.1601/nm.2557" xlink:type="simple">Pseudomonas alcaligenes</jats:ext-link> </jats:named-content> </jats:italic>, function as reservoirs of drug resistance-associated genes encoding carbapenemases in clinical settings.</jats:p> <jats:p> <jats:bold>Methodology.</jats:bold> Active surveillance for carbapenem-resistant Gram-negative pathogens was conducted in 2019 at a hospital in Tokyo, Japan. Of the 543 samples screened for carbapenem-resistant isolates, 2 were species of <jats:italic> <jats:named-content content-type="genus"> <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://doi.org/10.1601/nm.2552" xlink:type="simple">Pseudomonas</jats:ext-link> </jats:named-content> </jats:italic>. One was from a stool sample from a medical staff member, and the other was from a stool sample from a hospitalized patient.</jats:p> <jats:p> <jats:bold>Results.</jats:bold> Whole-genome sequencing showed that the former isolate was a strain of <jats:italic> <jats:named-content content-type="species"> <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://doi.org/10.1601/nm.2557" xlink:type="simple">P. alcaligenes</jats:ext-link> </jats:named-content> </jats:italic>, and the latter was a strain of <jats:italic>Pseudomonas paralcaligenes</jats:italic>, a species close to <jats:italic> <jats:named-content content-type="species"> <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://doi.org/10.1601/nm.2557" xlink:type="simple">P. alcaligenes</jats:ext-link> </jats:named-content> </jats:italic>. Both isolates were resistant to all carbapenems and harboured <jats:italic>bla</jats:italic> <jats:sub>IMP-1</jats:sub> genes encoding IMP-1 MBL, which conferred resistance to carbapenems. The <jats:italic>bla</jats:italic> <jats:sub>IMP-1</jats:sub> genes of <jats:italic> <jats:named-content content-type="species"> <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://doi.org/10.1601/nm.2557" xlink:type="simple">P. alcaligenes</jats:ext-link> </jats:named-content> </jats:italic> and <jats:italic>P. paralcaligenes</jats:italic> were located on the plasmids, pMRCP2, 323125 bp in size, and pMRCP1333, 16592 bp in size, respectively. The sequence of 82 % of pMRCP2 was 92 % similar to the sequence of a plasmid of <jats:italic> <jats:named-content content-type="species"> <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://doi.org/10.1601/nm.2553" xlink:type="simple">P. aeruginosa</jats:ext-link> </jats:named-content> </jats:italic> PA83, whereas the sequence of 79 % of pMRCP1333 was >95 % similar to the sequence of a plasmid of <jats:italic> <jats:named-content content-type="species"> <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://doi.org/10.1601/nm.10553" xlink:type="simple">Achromobacter xylosoxidans</jats:ext-link> </jats:named-content> </jats:italic> FDAARGOS 162. The genomic environments surrounding the <jats:italic>bla</jats:italic> <jats:sub>IMP-1</jats:sub> of pMRCP2 and pMRCP1333 differed completely from each other.</jats:p> <jats:p> <jats:bold>Conclusions.</jats:bold> These results indicate that the two isolates acquired <jats:italic>bla</jats:italic> <jats:sub>IMP-1</jats:sub> from different sources and that <jats:italic> <jats:named-content content-type="species"> <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://doi.org/10.1601/nm.2557" xlink:type="simple">P. alcaligenes</jats:ext-link> </jats:named-content> </jats:italic> and <jats:italic>P. paralcaligenes</jats:italic> function as vectors and reservoirs of carbapenem-resistant genes in hospitals.</jats:p>