AUTHOR=Wang Li , Fang Haihong , Feng Jiao , Yin Zhe , Xie Xiaofang , Zhu Xueming , Wang Jie , Chen Weijun , Yang Ruisheng , Du Hong , Zhou Dongsheng 

TITLE=Complete sequences of KPC-2-encoding plasmid p628-KPC and CTX-M-55-encoding p628-CTXM coexisted in Klebsiella pneumoniae

JOURNAL=Frontiers in Microbiology

VOLUME=6

YEAR=2015

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2015.00838

DOI=10.3389/fmicb.2015.00838

ISSN=1664-302X

ABSTRACT=<p>A carbapenem-resistant <italic>Klebsiella pneumoniae</italic> strain 628 was isolated from a human case of intracranial infection in a Chinese teaching hospital. Strain 628 produces KPC-2 and CTX-M-55 encoded by two different conjugative plasmids, i.e., the IncFII<sub>K</sub> plasmid p628-KPC and the IncI1 plasmid p628-CTXM respectively. <italic>bla</italic><sub>KPC−2</sub> is captured by a Tn<italic>1722</italic>-based unit transposon with a linear structure. ΔTn<italic>3</italic>-IS<italic>Kpn27-bla</italic><sub>KPC−2</sub>-ΔIS<italic>Kpn6</italic>-ΔTn<italic>1722</italic> and this transposon together with a mercury resistance <italic>(mer</italic>) gene locus constitutes a 34 kb acquired drug-resistance region. <italic>bla</italic><sub>KPC−2</sub> has two transcription starts (nucleotides G and C located at 39 and 250 bp upstream of its coding region respectively) which correspond to two promoters, i.e., the intrinsic P1 and the upstream ISK<italic>pn27</italic>/Tn<italic>3</italic>-provided P2 with the core −35/−10 elements TAATCC/TTACAT and TTGACA/AATAAT respectively. <italic>bla</italic><sub>CTX−M−55</sub> is mobilized in an IS<italic>Ecp1</italic>-<italic>bla</italic><sub>CTX−M−55</sub>-Δ<italic>orf477</italic> transposition unit and appears to be the sole drug-resistant determinant in p628-CTXM. <italic>bla</italic><sub>CTX−M−55</sub> possesses a single transcription start (nucleotides G located at 116 bp upstream of its coding region) corresponding to the IS<italic>Ecp1</italic>-provided P1 promoter with the core −35/−10 element TTGAAA/TACAAT. All the above detected promoters display a characteristic of constitutive expression. Coexistence of <italic>bla</italic><sub>KPC</sub> and <italic>bla</italic><sub>CTX−M</sub> in <italic>K. pneumoniae</italic> has been reported many times but this is the first report to gain deep insights into genetic platforms, promoters, and expression of the two coexisting <italic>bla</italic> genes with determination of entire nucleotide sequences of the two corresponding plasmids.</p>