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16 Cards in this Set
- Front
- Back
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List the most common kinds of organisms in the normal flora
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Bacteria
Some yeast, Candida is commonly present A few protozoa Latent viruses like Epstein-Barr virus (glandular fever) Herpes Simplex (cold sores) |
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Define: Transients
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organisms that are removed quickly, eg by washing
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What are the functions of normal flora?
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They create an environment which will reduce colonisation by other species eg reduce the pH
Produce antibacterial chemicals Intestinal bacteria produce vitamins used by the host Prevent infection eg pseudomembranous colitis, thrush which can occur when the normal flora are removed by antibiotic therapy |
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What is an endogenous infection?
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infection by pathogen from the human host, eg skin bacterium like Staphylococcus epidermidis, or Staph aureus from the nose causing wound infection, eg E. Coli from the colon causing bladder infection
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What is a Congenital Infection?
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a type of endogenous infection , a pathogen is transferred to foetus or neo-nate from its mother eg rubella, syphilis toxoplasmosis, hepatitis group B streptococci, HIV
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What is an Exogenous Infection?
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infection by organism from external environment eg another person
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What is a Health Care Associated Infection (HCAI)?
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infection acquired during a patient’s stay in hospital.
Previously called Hospital acquired Infection (HAI) and Nosocomial Infections |
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What is an Opportunistic Infection?
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infection by a microorganism that would not normally cause infection, but do so because of alteration in the condition of the host, or displacement of the microorganism.
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Describe the Disease Process
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the microorganism is ACQUIRED by the host
COLONISATION occurs host tissues are PENETRATED the microorganism SPREADS within host tissues the microorganism DAMAGES host tissues the infection is RESOLVED by host defences |
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Describe the process of Acquiring Microorganisms
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Microorganisms acquired from exogenous sources need a Route of Transmission. The major ones are;
Direct (horizontal, vertical, animal) Indirect (fomite, faecal – oral (hands, food), droplet (cough, sneeze, talk) vehicle (food, air, water), vector (mechanical eg fly, biological eg mosquito |
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Define: Colonisation
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refers to the presence and growth of a microorganism on skin or mucus membranes without evidence of infection.
A common scenario is for a patient admitted to hospital to be colonised with hospital strains |
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Define: Pathogenicity
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The ability to cause disease
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Define virulence
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Differences in pathogenicity are also referred to as virulence of the organism
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What are the properties of virulence?
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Infectivity - how easily the microbe enters the host, attaches to host cells or tissues, survives the normal host defenses and establishes infection
The severity of the damage it causes the infected host. |
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Define: Infective Dose
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the number of microorganisms required to cause observable infectious disease
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What are Virulence Factors?
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Factors which favour the establishment of Disease
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