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Antibiotic resistance of Flavobacterium and related genera


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Thomson, KS 1988 , 'Antibiotic resistance of Flavobacterium and related genera', PhD thesis, University of Tasmania.

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The genus Flavobacterium is characterized by high levels
of resistance to a wide range of antibiotics. Clinical
laboratories may experience difficulty in detecting this
resistance, the underlying mechanisms of which are unknown.
Genetically the genus is so diverse that it may eventually be
subdivided into at least four genera. Furthermore within the
genus some species are genetically heterogeneous and warrant
subdivision into further species. To date these taxonomic
reforms have not been possible because of a lack of
phenotypic markers which can be correlated with the genetic
differences. An additional taxonomic problem which requires
clarification is the relationship of Flavobacterium to other
genera, particularly Cytophaga and Bacteroides.
In this study eighty nine Flavobacterium study strains and
43 reference strains were tested to investigate the
susceptibility of the genus to antibiotics. Cell-free betalactamase
preparations of selected strains were used to
determine the substrate profiles, inhibitor profiles,
inducibility and isoelectric points of the beta-lactamases of
the genus and some related organisms. Preliminary data were
obtained about the roles of beta-lactamases and outer membrane
permeability in resistance to beta-l actam antibiotics.
Although two standardised conventional antibiotic
susceptibil ity testing techniques showed poor correlation
the antibiotic resistance patterns were nevertheless specific

for certain species and for groups of flavobacteria,
indicating that antibiotic resistance is of taxonomic utility
for this genus. Flavobacterium aquatile, F· breve, F.·
meningosepticum and F. odoratum could be readily delineated by
their susceptibility patterns. Similarities in the
antibiograms and beta-lactamases of F. multivorum, F.
spiritivorum and F. thalpophilum was further evidence of the
relatedness of these species and supported suggestions that
they be recognised as a separate genus.
The beta-lactamases of the genus Flavobacterium are
characteristically chromosomally mediated beta-lactamases of
Richmond and Sykes Class IV. Many Flavobacterium betalactamases
were unusual in exhibiting activity against the new
beta-lactamase resistant antibiotics cefoxitin and cefotaxime,
and occasionally imipenem. This suggested that these enzymes
are Class IV oxyiminocephalosporinases. This finding is of
taxonomic significance. It is also of clinical and
pharmaceutical significance in that it identifies
Flavobacterium as a genus capable of inactivating the latest
beta-lactam antibiotics and therefore requiring close
examination by research chemists if they are to succeed in
producing antibiotics which can evade the resistance
mechanisms of pathogenic bacteria.

Item Type: Thesis - PhD
Authors/Creators:Thomson, KS
Keywords: Beta-lactam antibiotics, Drug resistance in microorganisms
Copyright Holders: The Author
Copyright Information:

Copyright 1988 the author - The University is continuing to endeavour to trace the copyright owner(s) and in the meantime this item has been reproduced here in good faith. We would be pleased to hear from the copyright owner(s).

Additional Information:

Thesis (Ph.D.)--University of Tasmania, 1989. Bibliography: p. 282-328

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