Clinical Microbiology Techniques Quiz

Sterilization, Disinfectants, and Antiseptics

• Sterilization is the killing of all living microbes, including spores.
• Disinfectants are antimicrobial agents applied to non-living objects to reduce pathogenic microorganisms.
• Antiseptics are antimicrobial substances applied to living tissue to reduce infection risk. Antiseptics must not harm living tissue.
• Not all disinfectants are antiseptics.

Sterilization Methods

• Sterilization methods are categorized into chemical and physical methods.

Chemical Sterilization

• Chemical sterilization is used for tools and devices sensitive to high heat or irradiation (e.g., plastics and rubber).
• Chemical liquid sterilization methods: includes solutions/liquids for sterilization.
• Chemical vapor sterilization methods: utilize vapor.

Disinfectant Classification

• High-level disinfectants: effective against a large number of spores after long exposure (e.g., hydrogen peroxide).
• Intermediate-level disinfectants: effective against some types of spores (e.g., 70% ethyl alcohol and isopropyl alcohol).
• Low-level disinfectants: effective primarily against vegetative bacteria and fungi (e.g., iodine solutions, providone-iodine).

Physical Sterilization Methods

• Physical sterilization methods utilize physical agents or processes to eliminate all microorganisms.

• Autoclaving (Moist Heat Sterilization): uses steam under pressure at higher temperatures (121°C or 250°F) to sterilize equipment, media, and tools.

• Dry Heat Sterilization: uses high temperatures (160-180°C or 320-356°F) to oxidize microbial cells in glassware and metal instruments.

• Filtration: removes microbes from liquids using filters with small pores; crucial for heat-sensitive materials.

• Radiation (Ionizing Radiation): uses gamma rays or electron beams to break down DNA in microorganisms, effective across heat-sensitive materials.

• Ultraviolet (UV) Radiation: damages the DNA of microorganisms by exposing them to UV-C light, commonly used for surfaces.

• Boiling: uses water at 100°C for 10-15 minutes, although this process is less effective than true sterilization and isn't effective against all spores.

• Incineration: destroys materials through high-temperature combustion, often used for medical waste.

Diagnosis of Bacteria (techniques)

• Microscopy: methods like Gram staining (classifying bacteria by cell wall) and acid-fast staining (detecting Mycobacterium species).
• Culture Methods: growing samples on agar plates and broth to observe growth, morphology, and color changes for characterizing bacterial agents.
• Biochemical Testing: use tests like catalase, coagulase, oxidase, and urease to detect unique enzyme properties, potentially identifying specific bacteria.
• Automated Systems: automated systems like VITEK, and Phenix automate these tests for quicker analysis.
• Molecular Methods: Polymerase Chain Reaction (PCR) detects bacteria DNA/RNA and aids identification. Other methods include DNA Sequencing (identifying based on genome).

Blood Analysis

• Complete Blood Count (CBC) analyzes blood components (RBCs, WBCs) to detect infections and disorders.
• Automated Hematology Analyzers: automated blood cell counters and measurement of related blood components/indicators.
• Blood Smear Microscopy: manually examines blood samples under a microscope, essential for observing cell morphology.
• Hemoglobin and Hematocrit Tests: measure hemoglobin & RBC proportion – critical for detecting anemia & conditions.
• Blood Coagulation Tests (PTT & PT): assess blood clotting for detecting bleeding disorders.

Additional Tests and Techniques

• Platelet Function Tests: assess platelet adhesion and aggregation; identify potential bleeding disorders.
• Flow Cytometry: analyze cells/cell populations using fluorescent antibodies
• Bone Marrow Analysis: analyses bone marrow for diagnoses related to hematological cancers, anemias, etc.
• Clinical Chemistry: measures chemical components using various methods like spectrophotometry, measuring substances like glucose, cholesterol in blood/bodily fluids. Measuring electrolytes, enzymes via specialized assays and electrophoresis.
• Electrolyte analysis: assesses electrolytes to detect kidney disease, dehydration, and heart issues.
• Immunoassays (ELISA): detect specific proteins & hormones utilizing antibodies for diagnosing infections, hormone imbalances, and cardiac related issues.
• Chromatography (GC & HPLC): separates and identifies compounds in bodily fluids.
• Automated Analyzers: combine multiple tests in one streamlined system for high throughput and quick results. .

Laboratory Safety

• First Aid: Maintain access to first aid kits, including eyewash stations and showers, to handle injuries
• Biochemical Hazards: proper storage & labeling of chemicals; work in fume hoods, properly dispose of waste.
• Biological Hazards: follow biosafety procedures, appropriately use biological equipment, appropriate personal protective equipment (PPE), properly dispose of biological waste.