LESSON 4

• MICR 21: MICROBIOLOGY AND PARASITOLOGY
• PROF. JHON ROBERT R. PELOBELLO
• COLLEGE OF NURSING 2026
• LESSON 4: CONTROLLING THE GROWTH OF MICROORGANISM
• Macronutrients


  Required in large amounts; has principal roles in cell structure and metabolism. Includes proteins, carbohydrates, CHON, S, P
• Micronutrients


  Required in minute amounts; involved in enzyme functions and protein structure maintenance. Includes minerals, trace elements
• Growth factors


  Organic compounds that cannot be synthesized by an organism & must be provided as a nutrient. Includes vitamins, amino acids
• Chemoorganotrophs

  Utilize organic compounds as energy source
• Chemolithotrophs


  Utilize inorganic compounds as energy source
• Phototrophs


  Utilize light energy as energy source
• Heterotrophs

  Carbon is obtained from one or another organic compound
• Autotrophs

  Uses carbon dioxide (CO2) as its carbon source
• Factors that affect control of microbial growth in vitro

  • Temperature
  • pH
  • Osmolarity
  • Oxygen concentration
• Physical control that affects control of microbial growth in vitro

  • Heat (moist and dry)
  • Filtration
  • Irradiation
  • Cold temperature
  • Desiccation
• Chemical control that affects control of microbial growth in vitro

  • Sterilant
  • Disinfectant
  • Sanitizer
  • Antiseptics or germicides

  
• Inhibitory agents - mechanisms

  • Inhibition of cell wall synthesis
  • Inhibition of nucleic acid synthesis, structure, or function
  • Inhibition of protein synthesis
  • Disruption of cell membrane structure or function
  • Antimetabolic activity or competitive antagonism
• Antibacterial agents

  • Penicillin
  • Aminoglycosides
  • Tetracycline
  • Chloramphenicol
  • The Bacillus antibiotics
  • New classes

  
• Antifungal agents


  • Macrolide polyene
  • Amphotericin B
  • Nystatin
  • Griseofulvin
  • Synthetic azoles
  • Flucytosine

  
• Antiparasitic agents


  • Antimalarial drugs
  • Anti-protozoal drugs
  • Anti-helminthic drugs
• Antiviral agents


  • Block penetration into host cell
  • Block transcription or translation
  • Nucleotide analogs
  • Prevent maturation of viral particles
  • Interferon
  • Highly Active Anti-Retroviral Therapy (HAART)
• Drug resistance


  • Decreased permeability to drug or increased elimination of drug from cell
  • Superbugs
• Empirical therapy


  Based on, concerned with, or verifiable by observation or experience. An "educated guess" based on the clinician's prior experiences with the patient's infectious disease
• Undesirable effects of empirical therapy

  • Selecting for drug resistance
  • Allergy
  • Drug toxicity
  • Superinfection