Affiliation:
1. Pharmaceutical Research Center, Meiji Seika Kaisha, Ltd., 760 Morooka-cho, Kohoku-ku, Yokohama 222-8567, Japan
Abstract
ABSTRACT
Horizontal gene transfer has been identified in only a small number of genes in
Haemophilus influenzae
, an organism which is naturally competent for transformation. This report provides evidence for the genetic transfer of the
ftsI
gene, which encodes penicillin-binding protein 3, in
H. influenzae
. Mosaic structures of the
ftsI
gene were found in several clinical isolates of
H. influenzae
. To identify the origin of the mosaic sequence, complete sequences of the corresponding gene from seven type strains of
Haemophilus
species were determined. Comparison of these sequences with mosaic regions identified a homologous recombination of the
ftsI
gene between
H. influenzae
and
Haemophilus haemolyticus
. Subsequently, ampicillin-resistant
H. influenzae
strains harboring identical
ftsI
sequences were genotyped by pulsed-field gel electrophoresis (PFGE). Divergent PFGE patterns among β-lactamase-nonproducing ampicillin-resistant (BLNAR) strains from different hospitals indicated the potential for the genetic transfer of the mutated
ftsI
gene between these isolates. Moreover, transfer of the
ftsI
gene from BLNAR strains to β-lactamase-nonproducing ampicillin-susceptible (BLNAS)
H. influenzae
strains was evaluated in vitro. Coincubation of a BLNAS strain (a rifampin-resistant mutant of strain Rd) and BLNAR strains resulted in the emergence of rifampin- and cefdinir-resistant clones at frequencies of 5.1 × 10
−7
to 1.5 × 10
−6
. Characterization of these doubly resistant mutants by DNA sequencing of the
ftsI
gene, susceptibility testing, and genotyping by PFGE revealed that the
ftsI
genes of BLNAR strains had transferred to BLNAS strains during coincubation. In conclusion, horizontal transfer of the
ftsI
gene in
H. influenzae
can occur in an intraspecies and an interspecies manner.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Pharmacology (medical),Pharmacology
Cited by
45 articles.
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