Biology 216 - Lect8L
Normal Flora and Oral Micro
Objectives: Understanding of normal flora so can tell when something is wrong.
I. Normal (indigenous) flora - 10 per 1 human cell
   Normal resident flora - always in particular site in healthy host
   Endogenous vs exogenous disease.
A. Establishment of norml flora
	1. Sterile at birth
	2. Vaginal flora, nurse, mom ........ no competition.
	      Unstable population until factors limit to proper niche 
	      Ex. Nasopharyngeal in hours; GI in days; 
	     Vulnerable period: GpB Strept, E. coli meningitis, 
		Chlamydia pneumonia.
	3. Change in flora during maturation:
	     a. S. sanguis  - appears as teeth erupt
	     b. Vaginal Lactobacilli determined by estrogen -> 
		glycogen deposition (birth and puberty)
	4. Problems with normal flora
	     a. Wrong place - E. coli UTI
	     b. Compromised host - alcoholic (anaerobes in lung); 
		CF lung (E. coli, Ps);
		Viridans Strept and prosthetic/congenital heart valve.
B. Specific normal flora by location - know majors.
	1. Skin - Staph, Micrococci, diphtheroids
	2. Mouth and Throat - alpha strept, Neisseria, Haem, anaerobes
		*Major source of endogenous disease 
		(endocarditis; lung abscess)
	3. GI - Stomach (sterile); Sm intestine (low numbers - site for disease)
		Lg intestine (10(12)/gm feces - anaerobes 100:1 
		- Bacteroides/Bifidobacterium/Fusobacterium)
		*Second major source of endogenous disease
	4. Genitourinary - anterior urethra (same as skin); 
		Vaginal (Lactobacilli, Neisseria, GpB strept 20%)
	5. Blood, CSF, Tissue, Lung - Sterile.
II. Oral Micro - 4 levels of progression
A. Dental Caries (tooth decay) - progressive demineralization
	1. Progression - Acquired pellicle (salivary glycoprotein); 
		S. sanguis and actino adhere
	     S. mutans produce dextran sucrase -> dextrans/levans (plaque)
	     Gnotobiotic mice + S. mutans -> caries (Koch's Postulates)
	2. Demineralization - Lactic acid bacteria (Lacto, Strepto) 
		- Acid trapped in plaque
	     Lacto counts correlate with cariogenic activity (Snyder media - today)
	3. Prevention - mechanical; decrease sucrose; 
		fluoride (incorporates in matrix in children)
B. Peridontal disease - plaque for days; inflammation; gums recede;
		local invasion; systemic infection.
 	1. Gingivitis - inflammation of gingiva (gums) - cause of tooth loss
	Microbe factors (LPS, acid, enzymes) - inflammation; Degranulation.
	Gums red, recede - not invasive; Treat by plaque control.
	2. Progressive peridontitis - Bacteroides predominate.
	Plaque advances; Tissues ulcerate and abscess (pus) pockets form.
	Resorption of bone - Pockets between gum and tooth; 
		peridontal membrane no longer holds.
	3. Acute necrotizing ulcerative gingivitis - poor oral hygiene and stress.
	Active penetration and infection of gum by anaerobes -> necrosis.
	Treat - debride, drain, antibiotics, plaque removal.
	4. Worst - anaerobes -> blood  -> lung and brain