Most common microorganism of oral flora | AIIMS MDS Preparations

Most common microorganism of oral flora are 

a) Aerobic streptococci b) Anaerobic streptococci 

c) Facultative streptococci d) B-hemolytic streptococci

Ans C. 

Facultative streptococci form the most numerous single group in the oral cavity

Averaging in most surveys nearly V2 the viable counts of saliva and dorsum of tungue and about J/4th of viable counts of plaque and gingival sulcus.

>- The pyogenic (hemolytic) varieties are usually scarce in the oral cavity this has been attributed to a salivary inhibitory factor distinct from lysozyme or hydrogen peroxide. The pyogenic streptococci isolated occasionally from the oral cavity probably derived frcnn the oronnsopharynx and should not be regarded as resident flora. By far the most abundant of oral streptococci are those considered in viridans gp. These were divided in two broad groups

i) Strept. salivarius

ii) Strept. mitis

Strept. salivarius - average about half the viable count of facultative streptococci from saliva or tungue scrapings.

This organism ordinarily numbers less than 1 % of viable count in plaque.

> Majority of other oral facultative streptococci are strep. mitis, mutans and sanguis.

> S.sanguis - makes up about V2 of the count of facultative streptococci in plaque, which seems to be their primary habitat - causes SABE

	Gingival crevice area	Dental plaque	tongue	saliva
Gram positive anaerobic cocci Streptococci s.salivarious Enterococci staphylococci	28.8 27.1 N.D 7.2 1.7	28.2 27.9 N.D    - 0.3	44.8 38.3 8.2 N.D 6.5	46.8 41.0 4.6 1.3 4.0
Gram(+)Anaerofcocci	7.4	12.6	4.2	13.0
Gram(-)fac.cocci	0.4	0.4	3.4	1.2
Gram(-)amaer cocci	10.7	6.4	16	15.9

So from the above references it is shown that facultative streptococci is the most common microorganism of oral  cavity.