4

• factors used to classify gram positive bacilli

  endospore forming - shape and staining - type of irregular shape or stain
• why need acid fast stain for mycobacterium

  no all bacteria stain well with gram stain, waxy cell wall doesn't allow stain to penetrate
• spores 


  highly resistant forms of bacteria that form when environmental conditions are adverse (non viable, non replicating)
• bacillus anthracis 


  spore forming gram positive bacilli. causes anthrax disease (inhaled, ingested or contaminate food) = skin sores, vomitting, septic shock
• bacillus cereus 


  spore forming gram positive bacilli. common cause of food poisoning, more serious in immunocompromised people
• diphtheria 


  toxin mediated, membrane on throat and bullock, vaccine preventable
• microbiome 


  microbial community that occupies a well defined habitat
• dysbiosis 


  an imbalance in the microbial community associated with disease
• causes of dysbiosis 


  overgrowth of commensals, loss of commensals, loss of diversity
• determinants of microbiota 


  environmental parameters, interactions between microbes, rapid evolution, unpredictable forces
• negative interaction between microbes

  bacteria produce antibiotics that inhibit the growth of competing bacteria
• positive microbes interaction


  crossfeeding
• how measure microbiota 


  DNA, RNA production (activity), proteins (being produced by bacteria), metabolite
• other factors influencing gut microbiome

  genetics, exercise, location, mode of delivery, diet, antibiotics, age
• role of gut microbiome - positive


  digestions, helps immune system, pathogen clearance, brain development
• negative effects gut microbiome

  allergy and metabolic syndromes
• diet high low high fibre

  human enzymes can't break down polysaccharides, fermented by gut bacteria in colon= microbiota associated with metabolic health
• untargeted microbiome interventions 


  exercise, nutrition, faecal microbiota transplant
• targeted microbiome interventions


  prebiotics, probiotics, synbiotics, postbiotics
• prebiotics 


  compound metabolised by and promotes healthy gut bacteria
• probiotics

  ingesting the bacteria themselves
• postbiotics 


  taking downstream product of healthy gut microbiome
• TB non infected people and death p.a

  30% worlds population infected with latent TB, 1.4 million deaths
• risk for TB


  poverty, overcrowding - has killed more people than any other infection
• acquisition of TB infection

  has no animal or environment reservoir, direct human to human via aerosol spread
• TB infectious dose


  very low 1-10 bacteria
• TB adhesion


  small droplet nuclei enter terminal airspaces of lung, phagocytes by alveolar macrophages, live within them and spread around body
• TB pathogenicity 


  largely due to host inflammatory reaction to the bacterium which causes tissue destruction (lungs - abnormal immune response as can't kill bacteria)
• latent TB


  after initial immune control of bacteria - can stay contained, be eliminated or if exposed to immune insult 10% will reactive into active TB
• primary TB infection 


  unable to control by innate or adaptive immune response = active TB in macrophages
• multidrug therapy 


  prevent emergence of resistant strains as a consequence of chance mutations in chromosome
• therapeutic manipulation of microbiota

  antibiotics - kill some bacteria, faecal oral transplant helps to outcompete bad bacteria
• where is clostridium difficile found

  in faeces of neonates and 30% hospital patients, they have a disrupted gut microbiome and in spores in environment
• why neonates risk of clostridium difficile infection

  low density of gut bacteria, rapid colonised with it and dominates - if it has to compete with other bacteria can't colonised gut
• what do toxin producing strain of clostridium cause

  antibiotic associated diarrhoea (during/after use) can be mild to severe and most severe form is colon ulcers
• what is clostridium difficile disease a result of

  disruption to gut microbiome
• treatment for clostridium difficile infection

  first antibiotics to kill the bacteria, if severe faecal transplant to restore gut microbiome and outcompete
• why asymptomatic c.difficile infection?

  have flora competing with the bacteria, bile acids and IgA to inhibit its growth
• why symptomatic c.difficile infection?

  antibiotics killed flora, proton pump inhibits acid secretion, toxins break down colon epithelium