Affiliation:
1. Institute of Farm Animal Genetics, Friedrich-Loeffler-Institut, 31535 Neustadt-Mariensee, Germany
2. Institute of Microbiology and Epizootics, Freie Universität Berlin, 14163 Berlin, Germany
Abstract
ABSTRACT
Bordetella bronchiseptica
is involved in respiratory tract infections mainly in dogs and pigs but may also cause infections in humans. Valid and representative data on antimicrobial susceptibility of
B. bronchiseptica
is rare. Approved antimicrobial susceptibility testing methods have been published, but very few clinical breakpoints are available. The MIC values are low for most agents but high for β-lactam antibiotics and macrolides. Information on the genetic basis of resistance is scarce. For a small number of isolates that are resistant or show elevated MICs, the molecular basis of resistance was identified. Three tetracycline resistance genes,
tet
(A),
tet
(C), and
tet
(31), coding for major facilitator superfamily efflux pumps, were identified. Two other major facilitator superfamily exporter genes confer resistance to chloramphenicol (
cmlB1
) or to chloramphenicol and florfenicol (
floR
). Two class B chloramphenicol acetyltransferase genes (
catB1
and
catB3
), which confer resistance to nonfluorinated phenicols by enzymatic inactivation, have been identified in
B. bronchiseptica
. Like the trimethoprim resistance genes
dfrA1
and
dfrB1
, which code for trimethoprim-insensitive dihydrofolate reductases, the genes
catB1
and
catB3
were located on gene cassettes and found in class 1 integrons also harboring the sulfonamide resistance gene
sul1
. In addition, the gene
sul2
has also been detected. Both
sul1
and
sul2
code for sulfonamide-insensitive dihydropteroate synthases. A gene cassette harboring the β-lactamase gene
bla
OXA-2
was also identified, whereas β-lactam resistance in
B. bronchiseptica
seems to be more likely due to reduced influx in combination with the species-specific β-lactamase encoded by
bla
BOR-1
. The resistance genes were mostly located on conjugative plasmids.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Cell Biology,Microbiology (medical),Genetics,General Immunology and Microbiology,Ecology,Physiology
Cited by
15 articles.
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