human microbiome

• microbiome / normal flora


  the mixture of organisms regularly present at any anatomical site
• symbiosis


  micro-organisms that form releationships with hosts
• colonization

  presence of micro-organisms on a body surface without causing damage to the host
• humans are colonized with micro-organisms
• some micro-organisms are resident colonizers and live on the body permanently
• some microorganisms are transient and may live on the body finitely or may come and go
• mutualism


  positive effect on both species
• parasitism


  one benifits while the other is harmed
• commensalism


  one benifits while nothing happens to the other
• antagonism


  negative effects for both species involved
• human body is a collection of environmental niches providing warmth, moistrure and food for micro-organisms
• opportunisitc pathogen


  only pathogenic in certain circumstances, such as a compromised host
• overt pathogen


  highly pathogenic potential, even in a healthy host
• factors that affect the content/diversity of the microbiome

  age, sex, genetics, diet, stress, medication
• the skin is the largest secretory organ
• predominant skin microbes

  staphylococcus, S. aureus, candida and malassezia in moist sites
• oral biofilms 


  dental plaque on tooth surface, require physical removal to prevent disease
• predominant oral microbes

  streptococcus, lactobacilli, neissiera, candida albicans
• large intestine predominant species

  anaerobic bacteroides and anaerobic lactic acid bacteria. E.coli
• benefits of the microbiome

  colonisation resistance, host immunity, nutritional benefits, digestion
• colonisation resistance

  prevention of pathogenic colonisation by competition for nutrients and space. good bacteria keep bad bacteria in check
• s. aureus 


  skin flora coloniser, wound infections and cellulitis, BSI that can lead to sepsis
• candida albicans

  oral cavity/vaginal. can cause thrush in those areas
• c. difficile

  bowel, kept in check by healthy gut flora, may overgorw after broad spectrum antibiotic use.
• probiotics are useful during antibiotic treatment to re-establish the natural balance