Diagnostic Microbiology and the Microflora Inhabiting the Human Body

To be able to provide effective treatment for the pathogens, it is imperative to identify them. Microbiology provides a vast collection of literature to help identify these microbes using a morphological feature, biochemical tests and other techniques based on these two. The present experiment aims to identify the bacteria present in the vaginal swab and faecal samples, to check whether these species are normal for this part of the body, or are indicative of infection.

VAGINAL SWAB 1 (V1): The bacteria isolated from vaginal swab 1 (V1) exhibit a negative gram reaction, and the cell was found to be rod-shaped, suggesting that V1 is a gram-negative bacillus. Further, the bacteria showed round, flat, small, colonies, which had entire margins and were cream in colour. These results are suggestive of the bacteria being coliform and most probably being E. coli. V1 showed growth on MacConkey agar, along with the change of colour. This result helps in the conclusion that V1 is lactose fermenting gram-negative bacilli since MacConkey agar is selective only for gram-negative bacteria and excludes all gram-positive bacteria as bile salts in this media inhibit the growth of gram-positive bacteria (Fluornoy, 1900). V1, therefore, belongs to the family of Enterobacteriaceae, and since it changes colour in MacConkey agar, it is again suggestive of E.coli, as, among the gram-negative bacteria, only E.coli is able to ferment lactose, and forms pink to red colonies (MacConkey, 1900). The absence of growth on mannitol salt agar and blood agar, further rules out the gram-positive cocci. A positive result for catalase test, rules out the possibility of Streptococci (Chester, 1979), while a positive oxidase test indicates it to anaerobic and hence confirms it to belong to Enterobacteriaceae (Baron, 1994). Thus V1 could be safely concluded to belong to the group of lactose fermenting Enterobacteriaceae.&nbsp. &nbsp.