Part of Thermo Fisher Scientific
METRONIDAZOLE DIAGNOSTIC DISCS (50 µG)
Code: DD0008
SULPHONAMIDE DIAGNOSTIC DISCS (1000 µG)
Code: DD0011
An aid in the identification of Gardnerella vaginalis.
Contents
DD0008. 1 cartridge. containing 50 discs.
DD0011. 1 cartridge. containing 50 discs.
Disc Contents
DD0008 Metronidazole 50 mg
DD0011 Sulphonamide 1000 mg
Description
Smith and Dunkelberg1 reported that metronidazole, previously
thought to inhibit obligately anaerobic bacteria only was found in vitro
to inhibit the growth of facultatively anaerobic strains of Gardnerella vaginalis
when using the agar diffusion method.
Small pleomorphic Gram negative rods associated with `non-specific’ bacterial
vaginitis were recognised by Gardner and Dukes2 as the aetiologic
agent. They named the organism Haemophilus vaginalis. However, in obvious
conflict with the accepted definition of the genus Haemophilus it does
not have a requirement for Haemin (X factor), Nicotinamide Adenine Dinucleotide
(NAD or V factor) or any other co-enzyme-like growth factor. On the basis of
microscopic morphology, Zinnemann and Turner3 argued that it should
be reclassified in the genus Corynebacterium and suggested the name Corynebacterium
vaginale.
Taxonomic studies4,5 have led to the naming of a new genus Gardnerella
for inclusion of the organisms previously classified as Haemophilus vaginalis
or Corynebacterium vaginale with the type species Gardnerella vaginalis.
Bailey et al.6 have recommended that the susceptibility and resistance
to metronidazole and sulphonamide in conjunction with fermentation tests should
be used as an aid in the separation of Gardnerella vaginalis from
other possibly unrecognised biotypes of Gardnerella vaginalis or other
vaginal bacteria that presumptively resemble the organism. They recommended
a content
of 50 mg metronidazole
per disc.
Bacterial group or species susceptibility to discs of:
sulphonamide(1mg) |
metronidazole(50m g) |
|
Gardnerella vaginalis |
R |
S |
Bifidobacteria and G. vaginalis- like organisms |
S |
S |
Streptococci |
R |
R |
Lactobacilli |
R |
R |
S: Susceptible R: Resistant
It has been shown7 that in the treatment of Gardnerella vaginalis-
associated vaginitis with metronidazole, the hydroxy metabolite may contribute
a significant antimicrobial effect, in view of its excellent activity in
vitro.
The diagnosis and treatment of non-specific vaginitis has been reviewed8.
Technique
Inoculate the isolation medium with the specimen and place a 50 mg
metronidazole disc and a 1000 mg sulphonamide disc on an area of the plate
where heavy, but not confluent, growth can be expected. Smith and Dunkelberg1
incubated at 35°C in air containing approximately 8% carbon dioxide, but
more recently Ralph et al.9 in a study of MICs of a number of antibiotics
for Gardnerella vaginalis reported that susceptibility to metronidazole was significantly
increased by incubation in an anaerobic atmosphere and more reliable results
may be expected by incubation under these conditions.
Gardnerella vaginalis is best isolated on Columbia Agar CM0331 with Gardnerella
vaginalis Supplement SR0119.
Quality Control
Use known strains of Gardnerella vaginalis to monitor the performance of the
discs.
References
1 Smith R. F. and Dunkelberg W. E. (1977) Sex. Trans. Dis. 4. 20-21.
2 Gardner H. L. and Dukes C. D. (1955) Am. J. Obstet. Gynecol. 60. 962-976.
3 Zinnemann K. and Turner G. C. (1963) J. Pathol. Bacteriol. 85. 213-219.
4 Piot P., Van Dyke E., Goodfellow M. and Falkow S. (1980) J. Gen. Microbiol.
119. 373-396.
5 Greenwood J. R. and Pickett M. J. (1980) Int. J. Syst. Becteriol. 30.
170-178.
6 Bailey R. K., Voss J. L. and Smith R. F. (1979) J. Clin. Microbiol.
9. 65-71.
7 Ralph E. D. and Amatnieks Y. E. (1980) Sex. Trans. Dis. 7. 157-160.
8 Clay J. (1981) J. Antimicrob. Chemotherapy 7. 501-504.
9 Ralph E. D., Austin T. W., Pattison F. L. M. and Schieven B. C. (1979) Sex.
Trans. Dis. 6. 199-202.