Oral Lab- Oral Microbes and UTI diagnosis

Dental plagues

are the most common human-residing biofilm

mostly caused by Streptococcus ssp. (Streptococcus mutans, Streptococcus mitis, etc)

Dental plaques can lead to dental caries (cavities) or periodontal disease

Mitis salivarius media (Selective media for viridans Strep)

Purpose: 1) Selective media for Streptococci, espec. S. mutans, S. mitis and S. salivarius

Rationale: Contains crystal violet and potassium tellurite to inhibit non-Streptococci bacteria

Contains dextrose and sucrose as fermentable carbohydrates, utilized by some species

Interpretation: S. mutans and S. mitis do not utilize sucrose, forming small, flat colonies

S. salivarius utilizes sucrose, forming “gum-drop” colonies

Snyder’s test (identification of Lactobacillus in saliva)

Purpose: 1) Presumptive identification of Lactobacillus in saliva

2) helps determine individual risk of developing dental caries (aka cavities)

(acid production from Lactobacillus erodes tooth enamel, enabling bacterial infection)

Rationale: Contains 2% glucose and bromcresol green dye to detect acid production

Media is at pH = 4.8, which inhibits the growth of non-acidophiles

Interpretation: Color change to yellow is positive, and indicates high susceptibility to cavities

Slight color change (to yellow-green) indicates moderate susceptibility to cavities

Media remaining green is negative

Snyder’s test results

MacConkey Agar

selective and differential media for enteric Bacteria

• Contains Crystal Violet and Bile Salts to inhibit the growth of G+ bacteria

• Contains neutral-red dye to detect Lactose fermentation (indicates coliforms)

Bacteriuria

is the presence of bacteria in the urine, regardless of whether symptoms are present. It is classified based on the clinical presentation of the patient and the quantitative concentration of bacteria found in a urine culture, measured in colony-forming units per milliliter (CFU/mL)

UTIs

cystitis, urethritis, prostatitis, pyelonephritis