Affiliation:
1. Department of Bacterial Pathogenesis and Infection Control, National Institute of Infectious Diseases, Tokyo, Japan
Abstract
ABSTRACT
Serratia marcescens
S-95, which displayed an unusually high degree of resistance to aminoglycosides, including kanamycins and gentamicins, was isolated in 2002 from a patient in Japan. The resistance was mediated by a large plasmid which was nonconjugative but transferable to an
Escherichia coli
recipient by transformation. The gene responsible for the aminoglycoside resistance was cloned and sequenced. The deduced amino acid sequence of the resistance gene shared 82% identity with RmtA, which was recently identified as 16S rRNA methylase conferring high-level aminoglycoside resistance in
Pseudomonas aeruginosa
. Histidine-tagged recombinant protein showed methylation activity against
E. coli
16S rRNA. The novel aminoglycoside resistance gene was therefore designated
rmtB
. The genetic environment of
rmtB
was further investigated. The sequence immediately upstream of
rmtB
contained the right end of transposon Tn
3
, including
bla
TEM
, while an open reading frame possibly encoding a transposase was identified downstream of the gene. This is the first report describing 16S rRNA methylase production in
S. marcescens
. The aminoglycoside resistance mechanism mediated by production of 16S rRNA methylase and subsequent ribosomal protection used to be confined to aminoglycoside-producing actinomycetes. However, it is now identified among pathogenic bacteria, including
Enterobacteriaceae
and
P. aeruginosa
in Japan. This is a cause for concern since other treatment options are often limited in patients requiring highly potent aminoglycosides such as amikacin and tobramycin.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Pharmacology (medical),Pharmacology
Cited by
141 articles.
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