Normal flora general, Role in health and disease

• What is the normal body flora?

  Mixture of microorganisms in healthy individuals

  
• How many microorganisms are typically found in the body?

  Approximately $10^{14}$
• Which types of microorganisms are not part of the normal flora?

  Parasites and viruses

  
• What is commensalism in relation to normal flora?

  No harm, no benefit to the host

  
• What is mutualism in the context of normal flora?

  Both microbe and host benefit

  
• What benefits does the host provide to the microbe in mutualism?

  Stable environment, nutrients, protection
• What benefits does the microbe provide to the host in mutualism?

  Nutritional and digestive benefits,

  Protection from pathogenic microbes,

  Induces development and activation of the immune system
• What are opportunistic pathogens?

  Potential pathogens causing infection when defenses are low

  
• What is resident flora?

  Strains occupying a body site indefinitely

  ¢ Non-pathogenic at the site they occupy

  ¢ Re-establishes itself if disturbed
• How does transient flora differ from resident flora?

  Transient flora inhabit a site temporarily

  
• What is the carrier state?

  Harboring a pathogenic agent without disease

  
• Which bacteria are commonly found in the upper respiratory tract?

  Staphylococcus spp. and Streptococcus spp.

  
• What is a common bacterium found on the skin?

  Staphylococcus spp.
• Which bacteria are found in the gastrointestinal tract?

  Escherichia coli and Klebsiella spp.
• What is the source of normal flora in newborns?

  Exposure to the vaginal tract or environment

  
• What factors influence the composition of gastrointestinal flora?

  Diet, age, and antibiotic use

  
• What is the role of normal flora in the immune system?

  Induces maturation and function of the immune system

  
• What is the significance of sterile sites in health?

  Interpretation of bacterial culture results

  
• What is the exclusionary effect of normal flora?

  Prevents pathogens from binding to receptors

  
• What are probiotics?

  Living organisms promoting health
• What are prebiotics?

  Non-digestible food stimulating growth or activity or GI microbiota, especially se and and lactobacillus bacteria
• What are the roles of normal flora?

  • Beneficial roles:
  • Exclusionary effect
  • Nutritional function
  • Immune system priming
  • Harmful roles:
  • Opportunistic infections
  • Competition for nutrients
  • Induces low grade toxemia
  • Transfer to susceptible host

  
• What are the types of normal flora?

  • Resident flora
  • Transient flora
  • Carrier state

  
• What are the factors influencing the composition of normal flora?

  • Prenatal factors
  • Neonatal factors
  • Postnatal factors
• What are the common organisms found in the gastrointestinal tract?

  • Lactobacilli
  • Enterococcus
  • Escherichia coli
  • Klebsiella spp.
• What happens to the vaginal microbiota at puberty?

  • Lactobacillus increases
  • pH changes to 5
• What is the impact of antibiotic overuse on gut flora?

  • Antibiotic associated diarrhea
  • Risk of Clostridium difficile infection
  • Pseudomembranous colitis
  • Toxic megacolon

  
• What is fecal microbiota transplantation?

  • Transfer of normal flora to restore gut health

  
• What are the dietary sources of normal flora?

  • Breast milk
  • Environmental sources

  
• The oral cavity is favorable for bacterial growth due to?

  • Moisture content
  • Presence of food particles
• What is the significance of the low pH in the stomach?

  • Sterile in most individuals
  • Flora increases as pH increases
• What are the common organisms found in the upper respiratory tract?

  • Staphylococcus aureus
  • Streptococcus pneumoniae
  • Corynebacteria

  
• Low bacterial count in the conjunctiva is maintained by?

  • Lysozyme in lachrymal secretions
  • Flushing by tears
  • Blinking mechanically removes bacteria
• Protection in the upper respiratory tract is achieved by?

  • Epithelial cilia movement
  • Flow of mucus produced by ciliated cells
  • Lysozyme in mucus .
  • Phagocytosis by macrophages

  
• What is the role of macrophages in the lower respiratory tract?

  • Phagocytosis of trapped bacteria

  
• What is the role of the gastrointestinal tract flora in digestion?

  • Aids in nutrient absorption and synthesis

  
• What happens to the vaginal microbiota at menopause?

  • Returns to prepuberty flora
• What is the significance of the sterile sites in health?

  • Important for interpreting bacterial cultures

  
• What are the common organisms found in the genital tract?

  • Lactobacillus spp.
  • Streptococcus agalactiae
• What is the role of dietary sources in normal flora development?

  • Provides nutrients for microbial growth