Cell Biology: Prokaryotic vs Eukaryotic Cells

Cell Types Comparison

• Eukaryotic cells have a membrane-bound nucleus, known as a true nucleus.
• Prokaryotic cells contain no true nucleus; DNA is in the cytoplasm.
• Bacteria are unicellular organisms with DNA and RNA, classified as prokaryotic.
• Viruses are acellular entities comprising either DNA or RNA and are obligate intracellular pathogens.

Cell Envelope Structure

• The cell envelope consists of three components:
  • Capsule
  • Cell wall
  • Cell (Plasma) membrane

Functions of Cellular Structures

• Cell Wall: Provides shape and osmotic protection.
• Ribosomes: Site for protein synthesis.
• Flagella: Enables movement of the cell.
• Pili: Facilitates attachment to surfaces.

Cell Membrane Functions

• Transports nutrients into the cell.
• Eliminates waste from the cell.
• Contains enzymes crucial for respiration.

Endospore Characteristics

• An endospore is the dormant, inactive form of a bacterium.
• It resists extreme conditions including:
  • Dryness
  • High temperatures
  • Bactericidal agents
  • Nutritional deficiencies

Types of Normal Flora

• Resident Flora: Permanently inhabits body sites, resistant to removal by routine hygiene.
• Transient Flora: Temporarily present, can be removed through routine hygiene practices.

Advantages of Normal Flora

• Synthesizes vitamins beneficial to the host.
• Prevents pathogen entry through:
  • Physical occupation of niches
  • Nutrient competition
  • Production of antibacterial substances

Transition of Normal Flora to Pathogenic State

• Normal flora can become pathogenic if:
  • Host immunity is compromised.
  • Flora accesses new tissue sites.
  • Prolonged use of antibiotics alters the flora balance.

Definitions of Key Terms

• Colonization: Multiplication of organism on a body surface without tissue invasion or disease.
• Infection: Involves multiplication within tissues, leading to tissue invasion and disease.
• Carrier: An asymptomatic individual harboring a pathogenic organism, capable of transmission.

Sterilization and Disinfection

• Sterilization: Complete destruction of all microorganisms, including spores.
• Disinfection: Reducing pathogenic microorganisms to non-harmful levels, not necessarily including spores.

Autoclave Monitoring

• Monitoring includes physical aspects such as pressure, temperature, and cycle duration.
• Utilizes chemical indicators and biological indicators to ensure effective sterilization.

Handwashing Guidelines

• Required when hands are visibly dirty or contaminated with blood/body fluids.
• Necessary when exposure to spore-forming organisms is suspected or confirmed.

Item Risk Categorization

• Critical Items: High-risk items that penetrate sterile tissues; require sterilization.
• Semi-Critical Items: Intermediate risk items that contact intact mucous membranes; undergo disinfection.
• Non-Critical Items: Low-risk items that only come into contact with intact skin; cleaning and drying typically suffice.

Hepatitis B Virus (HBV)

• Transmission Modes: Blood, sexual intercourse, perinatal routes.
• Complications: Can include asymptomatic cases, chronic carriers, chronic active hepatitis, liver cirrhosis, and hepatocellular carcinoma (HCC).
• Clinical Presentations: Symptoms include fever and jaundice.

HBV Prevention Strategies

• Active Immunization: Three intramuscular doses (0, 1, and 6 months) in appropriate muscle site based on age.
• Passive Immunization: Administering HBIG with the vaccine for post-exposure prophylaxis.
• Hygienic Measures: Standard safety practices to prevent transmission.

Prevention of Catheter-Associated Urinary Tract Infections (CAUTI)

• Use catheters only when necessary.
• Remove catheters promptly when no longer needed.
• Ensure aseptic technique during insertion.
• Maintain a closed drainage system.
• Ensure unobstructed urinary flow.