MICB 202 Bacterial Diseases 1: Intro and 2: Normal Flora
Terms
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- Secondary Infection
- a later or second infection cause by an opportunistic organism after a primary infection has weakened the host defenses
- Factors that affect conposition of normal flora
- 1-diet 2-infection (results in a temporary increase in pathogen numbers) 3- oral antibiotic therapy (decreases normal flora which allows opportunistic bacteria to move in. after antibiotic treatment is done normal flora take over again)
- Characteristics of Gnotobiotic animals and birds
- 1-abnormal anatomical and physiological features 2-underdeveloped lymphatic tissue and poorly developed immune systems 3-thin intestinal wall 4-low antibody titer 5-higher susceptibility to pathogens 6-reduced susceptibility to certain disease processes which are dependant on the activity of microbes (e.g. dental caries)
- Organisms in the Normal Flora
- mostly bacteria with a few eukaryotic fungi and mehtanogenic archaea in the lower intestinal tract
- Factors that affect the microorganism/host relationship
- the pathogenicity of the microbe and the resistance or susceptibility of the host
- Disease
- is damage or injury to the body that impairs function
- Ideal areas of the skin for bacterial growth
- near sweat glands (armpits, genital region, between the toes) and the upper region of hair follicles
- Virulence
- a measure of pathogenicity or a microorganism and it is a quantitative concept. It can be expressed as the cell number that will elicit a pathogenic response in the host within a given time period
- Gnotobiotic
- literally "known life" but typically means germ free
- 6 factors that compromise the immune defences of a host
- 1-underlying disease or infection (AIDS, cancer, inherited immunodeficiences) 2-stress (exam time at UBC and we all get a cold) 3-poor nutrition (a diet that leaves out certain vitamins,etc) 4-Age 5-Immunosuppressive Therapy (cancer treatment or transplant maintenance drugs) 6-Genetics of the host (some people are more susceptible to certain bugs than others)
- Gingivitis
- an inflammatory condition of the gums
- Local Infection
- is restricted to a relatively small area of the body and are usually caused by non-invasive organisms
- Unwanted Aspects of Host-normal flora relationship
- 1-the pathogenic potential of the normal flora if introduced into other location in the body(eg. E. coli is normal in the GI but may cause infection if it gets in the urinary tract) 2-the production of intestinal gas (intestinal flora are responsible for the production of approx 300-400 ml gas/day)
- Microbial anatgonism
- the normal flora of the host inhibits colonization by pathogens by occupying adherence sites, untilizing nutrients, producing inhibitory byproducts and affecting conditions such as pH and available oxygen
- How soon and fecal cultures positive after birth?
- 10-20 hours
- Main type of bacteria in the GI tract
- anaerobic
- Focal Infections
- begin in a restricted area and then spreads throughout the body
- Factors affecting bacteria location
- 1-possibly prescence of growth factor or simple tissue preference/some parts of the body are inhospitable due to pH, etc. 2-prescence of host receptors necessary for colonization 3-prescence of bacterial biofilms
- Avirulent
- organisms that rarely, if ever, cause disease
- Benefits for the Bacteria in the host
- 1-supply of nutrients 2-stable environment 3-mode of transport
- Systemic or Generalized Infection
- one which is soread throughout thhe body and are often caused by invasive organisms
- Compromised Host
- a host whose immune defence system is weakened
- Nosocomial Infection
- one aquired as a consequence of hospitalization
- Strain
- a population of bacteria that are all descended from a single cell in a clonal fashion
- Opportunistic Pathogen
- a bacterium that harms a compromised host
- Source of Normal Flora at birth
- 1-passage through the birth canal 2-exposure to other humans and pets 3-ingestion of food and fluids 4-inhalation of air-borne microorganisms
- Main bacteria in the GI of solid food or cow's milk fed babies
- Bacteriodes, Enterococci, Lactobacilli and Clostridia as well as Bifidobacteria
- Pathogenicity
- is the ability of an organism to cause disease and is a qualitative concept
- Periodontal diseases
- are bacterial infections that affect the supporting structures of the teeth (gingiva, cementum, periodontal membrane and alveolar bone) ex. gingivitis
- Factors that affect normal flora on the skin
- 1-weather 2-age 3-personal hygiene 4-diet
- Primary Infection
- an intial, acute infection
- 4 Potential outcomes of a microorganismal encounter
- 1- pass through the body as a harmless transient 2- colonize the body and become part of the normal flora 3- establish an infection in the body 4- establish an infection in the body and cause disease
- Pathogen
- a bacterium that is capable of harming a normal host
- Infection
- the invasion or colonization of the body by pathogenic microorganisms that may not always result in damage or injury to the body
- Classifications of Infections based on invasiveness
- local, systemic/generalized or focal infections
- How soon are mouth sultures positive after birth?
- 6 hours
- Factors that may affect virulence
- route of entry and the general health/susceptibility of the host. It is usually correlated with the Pathogens ability to multiply within the host
- Benefits of stimulation of the immune system by normal flora
- the normal flora can induce an antibdy response in the host and low levels of antibodies against components of the normal flora (sometimes called 'natural antibodies') can cross react with certain related pathogens and thereby prevent infection or invasion
- Normal Bacteria in nostrils
- Staphylococcus epidermis and sometimes Staphylococcus aureus (a potential pathogen)
- Normal bacteria in the sinuses
- none
- Classifications of Bacterial Infections
- primary, secondary, subclinical or nosocomial
- Nutritional synergisms
- bacteria in the intestinal tract are involved in 1-synthesis and excretion of vitamins in excess of their own needs which can be absorbed as nutrients by the host (ex. vitamin K, B12) 2-steroid metabolism (ex. bile acids are converted to steroids that are reabsorbed by the host) 3- organic acid production(ex. acetic acid) 4-glycosidase reactions (ex. sugar fermentations)
- Dental caries are
- otherwise known as cavities; they are the destructio of the enamel, dentin or cementum of teeth caused by acid-producing bacteria in plaque
- Subclinical Infection
- one in which the host has no apparent symptoms
- Normal Flora
- Microorganisms that reside in or on the body without causing disease
- Normal Host
- an individual whose defence mechanism are not compromised in any substantial fashion
- Benefits for the Host containing the bacteria
- 1-microbial antagonism 2-nutritional syergisms 3-stimulation of the immune system
- Main bacteria in the GI of breast fed babies
- Bifidobacteria