Bacterial Inflammation Response and Identification Techniques

Inflammation Response Purposes

Flash: Inflammation occurs for two primary purposes:

1. To destroy or neutralize the offending agent and/or, if not possible, to limit its effects.
2. To facilitate the repair of the injury.

(This response is seen in serous, catarrhal, hemorrhagic, and purulent inflammations.)

Infectious Agents

Agents involved in infections include Gram-positive cocci, Enterobacteriaceae, and Haemophilus.

Enterobacteriaceae Characteristics

Enterobacteriaceae are Gram-negative, enteric, straight, non-spore-forming rods. They ferment glucose, reduce nitrate to nitrite, grow on ordinary media, and are oxidase-negative. MacConkey Agar is the medium utilized for the isolation of most enterobacteria.

Diagnostic Media for Enterobacteriaceae

1. Lysine Iron Agar (LIA)

LIA detects hydrogen sulfide production, lysine decarboxylation, and phenylalanine deamination. The medium contains glucose, lysine, ferric ammonium citrate (III) for H2S detection, and bromocresol purple as a pH indicator.

Production of H2S: Formation of a black precipitate at the bottom of the tube indicates H2S production.

2. Motility, Indole, Ornithine (MIO) Test

This is a semisolid medium used to determine motility, indole production, and ornithine decarboxylation. Indole production is visualized by adding Kovac's reagent.

3. Triple Sugar Iron Agar (TSI)

TSI is a differential medium containing glucose, ten times more lactose than glucose, and sucrose. It includes an indicator system to detect H2S production and phenol red as a pH indicator.

Gram-Negative Nonfermenters (BNF)

This group of microorganisms does not form a taxonomically well-defined cluster. They are characterized by their inability to ferment glucose, are non-sporulating, aerobic, show no changes on TSI and Kliger's agar, and are negative for indole and ornithine decarboxylase.

Principal Isolated Genera of BNF

The principal actors isolated are: Pseudomonas, Acinetobacter, Flavobacterium, Moraxella, and Alcaligenes.

Bacterial Classification of BNF Groups

1. Motile rods, oxidase positive: Pseudomonas and Alcaligenes Genera.
2. Non-motile coccobacilli, oxidase negative: Acinetobacter Genus.
3. Non-motile coccobacilli, oxidase positive: Moraxella and Flavobacterium Genera.

Recognition of BNF

1. Growth without changes in the slant and butt of Kliger's and TSI media.
2. Positive cytochrome oxidase reaction.
3. Inability of the bacteria to grow on MacConkey Agar.

Features Used to Differentiate BNF Genera

• Glucose Utilization
• Motility
• Cytochrome Oxidase Activity
• Ability to grow on MacConkey Agar
• Cellular Morphology