Objective—To determine whether a novel third-generation chelating agent (8mM disodium EDTA dehydrate and 20mM 2-amino-2-hydroxymethyl-1, 3-propanediol) would act as an antimicrobial potentiator to enhance in vitro activity of antifungal medications against fungal isolates obtained from horses with mycotic keratitis.
Sample Population—Fungal isolates (3 Aspergillus isolates, 5 Fusarium isolates, 1 Penicillium isolate, 1 Cladosporium isolate, and 1 Curvularia isolate) obtained from horses with mycotic keratitis and 2 quality-control strains obtained from the American Type Culture Collection (ATCC; Candida albicans ATCC 90028 and Paecilomyces variotii ATCC 36257).
Procedure—Minimum inhibitory concentrations (MICs) against fungal isolates for 4 antifungal drugs (miconazole, ketoconazole, itraconazole, and natamycin) were compared with MICs against fungal isolates for the combinations of each of the 4 antifungal drugs and the chelating agent. The Clinical and Laboratory Standards Institute microdilution assay method was performed by use of reference-grade antifungal powders against the fungal isolates and quality-control strains of fungi.
Results—Values for the MIC at which the antifungal drugs decreased the growth of an organism by 50% (MIC50) and 90% (MIC90) were decreased for the control strains and ophthalmic fungal isolates by 50% to 100% when the drugs were used in combination with the chelating agent at a concentration of up to 540 μg/mL.
Conclusions and Clinical Relevance—The chelating agent increased in vitro activity of antifungal drugs against common fungal pathogens isolated from eyes of horses with mycotic keratitis.
Objective—To determine whether an inactivated culture
of a microcin-producing avian Escherichia coli
was capable of killing Salmonella isolates from reptiles
in an in vitro test system.
Sample Population—57 Salmonella isolate from reptiles.
Procedure—A wild-type avian E coli electrotransformed
with a plasmid coding for the production of
microcin 24 was tested in an in vitro microassay system
for its ability to kill 57 Salmonella spp isolated
from reptiles. The reptile population included snakes,
iguana, frilled lizards, turtles, other lizards, and
Results—44 of the Salmonella isolates were inhibited
strongly, compared with the in vitro assay controls; 12
had weak inhibition, and 1 was not inhibited by the
microcin-producing E coli. Thirteen of the 57 isolates
had resistance to at least 1 antibiotic, primarily streptomycin.
There were 9 O serogroups identified in the
57 isolates, with serogroup H being the most prevalent
(18 to 57).
Conclusion and Clinical Relevance—Antibiotics are
not recommended to eliminate Salmonella organisms
from reptiles because of the development of antibiotic
resistance. Further studies are necessary to determine
whether the use of microcin-producing bacteria will be
effective in controlling Salmonella infections in companion
reptiles. (Am J Vet Res 2001;62:1399–1401)