Which of the following organism represents the normal vaginal anaerobic flora?
Lactobacillus is a gram positive, non spore forming anaerobic rod. It is a normal flora of mouth, colon, and female genital tract. In the vagina it is the main source of lactic acid which keeps the pH low. Lactobacillus does not possess catalase, so it cannot breakdown H2O2. It produces bacteriocin, a low molecular weight protein that has antibacterial propeies. Thus, when the vaginal ecosystem is in a balanced equilibrium and Lactobacillus is dominant the pathogenic bacteria are maintained in a suppressed state and pose no threat to obstetric health of the patient. Bacterial vaginosis is caused by an alteration in the normal vaginal flora. In this condition there is overgrowth of organisms such as Gardnerella vaginalis, Mobiluncus spp., anaerobic gram-negative rods and Peptostreptococcus spp. Ref: Levinson W. (2012). Chapter 27. Minor Bacterial Pathogens. In W. Levinson (Ed), Review of Medical Microbiology & Immunology, 12e. Advances in Reconstructive Vaginal Surgery By S. Robe Kovac page 452.
Lactobacillus
Gardenella
Corynebacterium
E. coli