Water Microbiology Notes

Water Microbiology

Water microbiology involves studying microorganisms in water, their effects on water, and health risks, especially preventing waterborne diseases.

Water in the Pharmaceutical Industry

Water is a crucial raw material in the pharmaceutical industry, often requiring strict quality control and validation. It can be used as an excipient, API, in product reconstitution, synthesis, production, or as a cleaning agent.

Sources of Water

Water sources include:

  1. Surface water (rivers, lakes, oceans, streams)

  2. Groundwater (aquifers, springs, wells, boreholes)

  3. Precipitation (rain, snow)

  4. Man-made sources (reservoirs, canals)

Types of Pharmaceutical Water

  • Non-potable water: Raw water, used for initial cleaning.

  • Potable water: Suitable for drinking, used in early cleaning and some synthesis.

  • Purified water: Used as excipients and in chemical preparations; produced via deionization, distillation, etc.

  • Water for injections: Used for cleaning sterile product contact surfaces and in sterile product preparations.

  • Bacteriostatic water for injections: Contains preservatives.

  • Sterile water for injections: Terminally sterilized, non-pyrogenic; used for reconstitution.

  • Sterile water for inhalations: For inhalation devices; not for parenteral use.

  • Sterile water for Irrigation: Used for rinsing wounds during minor surgical procedures or urethral irrigation. Remnant are discarded per packaged container after usage.

Common Water Contaminants

  • Suspended solid particles

  • Colloids

  • Dissolved inorganic salts

  • Dissolved organic compounds

  • Micro-organisms

  • Pyrogens

  • Dissolved gasses

Pharmaceutical Compendium on Water

Pharmacists need training on water grades for manufacturing APIs and medicinal products. Standard pharmacopeias (Ph Eur, USP) specify standards for:

  • Purified water

  • Highly purified water

  • Water for injections

Potable water standards are set by competent authorities and testing should be done at the production site to confirm quality and standard.

Standard Pharmacopoeia Water Grades

  1. Purified Water: For medicinal products, excluding sterile or apyrogenic applications. Production methods include distillation, ion exchange, filtration, or reverse osmosis.

  2. Highly Purified Water: Purified water with extensive purification for high biological quality products. Methods include ultra filtration and deionization.

  3. Water for Injections (WFI): For parenteral medicines; produced from potable or purified water by multi-column distillation; must meet specific quality, endotoxin removal, ionic, and organic chemical standards.

USP Monographs

  • Type I: Ultra-pure water and water for injection.

  • Type II: Primary grade water/laboratory grade/highly purified water.

  • Type III: General grade water/purified water.

  • Type IV: Feedwater/water with common contaminants.

Water Production

Water production includes treatment and purification processes. Treated water is processed for specific uses, while purified water undergoes contaminant removal for higher purity.

Methods of Water Purification

Common methods for pharmaceutical water include:

  1. Distillation

  2. Deionization

  3. Filtration

  4. Reverse osmosis

  5. Photo-oxidation

  6. Irradiation

Distillation

Removing water from impurities via evaporation and condensation.

  • Simple Distillation: Basic evaporation and condensation.

  • Steam distillation: Uses steam for heat-sensitive compounds.

  • Fractional Distillation: Separates liquids with close boiling points using a fractionating column.

  • Multicolumn Distillation: Series of columns for high purity, like WFI.

  • Vacuum Distillation: Lowers boiling points to prevent decomposition.

Deionization

Removes ions using ion exchange resins. Distilled water is used as feed for high purity.

Filtration

  • Microporous filtration: Removes bacteria using 0.2μm membrane.

  • Ultrafiltration: Removes pyrogens and organics using 1-10nm membrane.

  • Activated carbon filters: Removes chlorine and some organics by adsorption.

Reverse Osmosis

Applies pressure to force water through a semi-permeable membrane, removing impurities.

Photo-Oxidation (Ultraviolet Oxidation)

UV light disinfects and ionizes organics. It eliminates trace organics at 185nm and inactivates microorganisms at 254nm.

Irradiation

Uses gamma rays or electron beams to inactivate bacteria and degrade pollutants.

Storage of Treated/Purified Water

Type I water is directly dispensed. Type II water should be stored for a maximum of 24-48 hours under sterile, airtight conditions with continuous recycle options. Glass vessels are often recommended. Reservoirs should also be protected from airborne impurities with suitable filters.

Water Quality Determination

Determined by physicochemical and microbiological quality parameters.

Physicochemical Quality

Includes physical (temperature, turbidity, color, taste, odor, solids) and chemical (pH, acidity, alkalinity, dissolved oxygen, BOD, COD, hardness, salinity, conductivity, ions, minerals) properties.

Microbiological Quality

Includes microbial enumeration (plate count, MPN) and microbial quality assays (indicator organisms, pathogens).

Bacteriological Water Analysis

Assesses bacteria presence and quantity, indicating contamination. Indicator organisms (coliforms, enterococci, Clostridium perfringens) suggest fecal contamination.

Methods of Bacteriological Water Assay

  1. Membrane Filtration: Traps bacteria on a membrane, cultured on selective media.

  2. Most Probable Number (MPN): Estimates bacteria density via dilutions and growth observation.

  3. Plate Count: Inoculates sample onto nutrient agar to determine bacterial density.

Characterization and Identification

Includes cultural characteristics, microscopy, biochemical tests, and PCR for pathogen analysis.