I – GENERAL ON VAGINOSIS:
The vaginosis or nonspecific vaginitis are frequent infections, characterized by vaginal discharge and due to other agents as Candida, Trichomonas, Neisseria gonorrhoeae or Chlamydia trachomatis.
This condition reflects an imbalance of the vaginal flora. Lactobacilli forming the normal flora of the vagina (flora Döderlein) disappeared and were replaced by abundant flora in which will be isolated:
– Gardnerella vaginalis
– Mobiluncus spp
– Anaerobic (Prevotella bivia, melaninogenica Prevotella, Peptostreptococcus, Veillonella …)
Diagnosing vaginosis be done on the following criteria:
1. Clinical appearance:
Presence of whitish vaginal discharge, adherent, uniform, sometimes smelly. They are often accompanied by any functional impairment, if not discomfort. However this infection favors the occurrence of complications with itching, cervicitis, vaginal inflammation or pelvic inflammatory disease especially during pregnancy.
2. Test potash:
The addition of potassium to 10% in the vaginal secretion causes the release of a probably smell of rotten fish related to the release of amines (putrescine and cadaverine), products of catabolism of lysine and ornithine.
3. A vaginal pH greater than 4.5:
4. A direct examination:
absence of polymorphonuclear unless inflammatory or infectious complication.
5. Gram staining:
disappearance or reduction of lactobacilli that are replaced by a monomorphic flora (Gardnerella) and erythema (anaerobic).
The presence of bacteria “comma” allows the diagnosis of infection Mobiluncus.
6. The presence of “clue cells”:
is an excellent diagnostic criterion Gardnerella infection: they are epithelial cells covered with numerous small bacilli regular shape and size that adhere to the surface of cells. This is observed by Gram stain (bacilli are then Gram variable) but also on the cytology smears.
In practice the direct examination allows the diagnosis of vaginosis and cultivation of bacteria involved, difficult and costly, provides only a late response.
The treatment of these episodes usually consists of the administration of metronidazole orally or locally (gynecological ovules).
We describe below the characteristics of the two main types involved in vaginosis: Gardnerella and Mobiluncusoften associated.
II – GARDNERELLA:
A – History:
In 1955, Gardner and Dukes showed the role in nonspecific vaginitis a bacillus which was successively calledHaemophilus vaginalis and vaginal Corynebacterium. In 1980, as a result of taxonomic work showing that this bacillus could be attached to one Either of these two types, the name of Gardnerella vaginalis was adopted.
B – Habitat and pathogenicity:
G. vaginalis can be isolated in the genital tract of women in the absence of symptoms. The frequency of porting is higher in women with a high sexual activity.
The pathogenic role of G. vaginalis was discussed. Nevertheless, it is certain that this bacterial species plays an important role in the development of vaginosis. Concomitant proliferation of anaerobic promotes that of G. vaginalis.
In humans, G. vaginalis is found in the urethra of most women infected partners. It is generally asymptomatic carriage.
C – bacteriological characters:
1. Body type:
G. vaginalis is a small bacillus Gram variable, motionless. The average length is from 1 to 2 .mu.m, sometimes coccobacillary. The bacterial bodies may associate in pairs or fences in the manner of corynebacteria.
2. Characters cuïturaux:
The culture of G. vaginalis is tricky. After inoculation on a rich medium, colonies develop in 48 to 72 hours at 37 ° C in an atmosphere of 5 to 10% CO2.
– Non-selective culture media: they consist of a rich base (Columbia) supplemented with 5% blood. On human blood agar, small gray-blue colonies are surrounded by a blur hemolysis P aboard area that is not observed in the blood of sheep or horse blood,
– Selective culture medium is obtained by addition of colistin, gentamicin or nalidixic acid,
3. Identification:
Suspect colonies are identified by the following tests:
– Human blood hemolysis,
– Absence of catalase and oxidase,
– Hippurate and starch,
– Attack glucose, maltose but not mannitol,
– Sensitivity to metronidazole concentration (disc 50 u, g), and trimethoprim,
– Resistance to sulfonamides and optochin.
API-Strept gallery allows identification of G. vaginalis.
III – MOBILUNCUS:
A – History:
The genus Mobiluncus was proposed in 1984 to describe bacteria that are mobile and curved {uncus). In 1985, with the morphology of the bacteria vibrio were observed in vaginal secretions. In 1940, Prevost had appointed the isolated vibrio cholerae mulieris Curtis in 1913. In 1980, Durieux and Dublanchet rattled by growing the “anaerobic vibrio” in 11% of the examined vaginal, highlighting the importance of these bacteria in nonspecific vaginitis .
B – Habitat and pathogenicity:
Mobiluncus can be isolated in small quantities in healthy carriers. When the concentration of Mobiluncus vaginosis in vaginal secretion is high.
C – bacteriological characters:
1. Morphology and mobility:
The Mobiluncus are bacilli January-March um long, curved in scratch and Gram variable. On smears, they often appear gram negative, but the structure of their wall is close to that of Gram-positive bacilli they are taxonomically closer.
They are mobile, with one or more polar or parapolaires eyelashes.
2. Cropping characters:
They are strictly anaerobic bacilli. They grow on Columbia agar enriched with 2.5 to 5% of blood. The medium can be made selective by the addition of 15 ug / ml nalidixic acid and 10 mcg / ml colistin. Colonies grow after 48 to 72 hours incubation at 37 ° C under anaerobic conditions.
3. Identification characters:
The Mobiluncus have neither catalase or oxidase. Two species are described:
– Mr. curtisii. The bacterial bodies are short (1.7 um long). This species hippurate hydrolysis, is poorly glucidolytique and is resistant to metronidazole.
There are two subspecies: M. curtisii subsp. curtisii which is negative nitrate reductase and M. curtisii subsp.holmesii which is positive nitrate reductase.
– Mr. mulieris. The bacterial bodies reach 3 microns long. This species does not hydrolyze hippurate and is highly glucidolytique.
4. Sensitivity to antibiotics:
Sensitivity to metronidazole is irregular. All strains were susceptible to penicillin, ampicillin, cefoxitin, erythromycin and paradoxically to an anaerobic, gentamicin.
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