Unit 1 Flashcards
(103 cards)
Micro-organisms
Can also be called a microbe, includes fungi and bacteria, includes viruses even though they are considered “non-living”
- not all micro-organisms are bad - yeast for beer, bacteria for cheese
- can be single or multi-called
Micro-organisms that cause illness …
Pathogenic
Bacteria
Living organism, unicellular, can cause disease, localized infections, treatment - antibiotics, and reproduces through fission - form of asexual reproduction
Viruses
Opinions differ on whether viruses are a form of life, or organic structures that interact with living organisms, no cells (not living), can cause disease, infections are systemic, treatment - vaccines prevent the spread of infection and anti-viral medications help to slow re-education but cannot stop it completely, reproduces invades a host cell and takes over the cell causing it to make copies of the viral DNA / RNA, destroys the host cell releasing new viruses
How to name bacteria based on their shape
Cocci - oval
Bacilli - rod
Spiral
Other - square, star, spindle
Naming bacteria based on gram staining
Gram negative - thin
Gram positive - thick
Broad spectrum antibiotics can be used for both types of bacteria
Staphylococcus aureus bacteria
Gram positive, round shaped bacterium, usually found in the upper respiratory tract and on the skin, causes variety of clinical diseases
Proliferation of antibiotic resistance strains of bacteria
Bacteria becoming immune to the effects of drugs, occurring because of abuse of antibiotics (banana flavoured penicillin), over prescription, unfinished course of treatments, food additives
Example - methicillin resistant staphylococcus aureus (MRSA)
Recurrence of disease thought to be under control or eradicated
Pertussis making a come back, tuberculosis (higher risk for indigenous and immigrants from endemic countries)
Source
Something that is contaminated with, or carries an infectious agent (blood covered gloves for example)
Reservoir
A place in which organisms can live and multiply
- Typhoid Mary (cook with salmonella thypi)
- ambulance equipment
Incubation period
The time between contact with an infectious agent and the presence of symptoms - can be long or short, HIV incubation period can be 7-10 years or Ebola virus - hours
- during the incubation period the host may or may not be infectious to others (contagious)
Communicable period
The time during which a person can transmit an infectious disease to others
- chicken pox communicable period is from approximately 2 days before the lesions break out until the lesions are crusted over
Exposure
Coming into contact with an infectious agent, having been exposed does not mean that you will become infected
Type of exposure needed to transmit disease varies depending on the infectious agent …
- chicken pox is highly contagious and you can become infected by being in the same room with a person in their communicable period
- HIV not highly contagious, need significant levels of direct exposure of contaminated body fluids with blood or mucous membranes
Physical barrier to infection
Intact skin - organisms cannot enter intact skin, body’s main dense against infection
Ciliary activity in mucous membranes (lungs)
Chemical barriers to infection
Acidic pH of the skin has inhibitory effect on bacteria, normal flora (the good bugs) keeps infection from invading organisms
Immune system as an infection barrier
Immune system - phagocytes - antibodies
- an intact immune system is also crucial to warding off infection
Immunity as infection barrier
Functions of the immune system, protects against disease or damaging foreign bodies, we get it from our moms, previous exposure or vaccines
Increasing ability of immune system to fight infection
- infant’s get immunity from mother’s blood and from breast feeding
- recent study compared infants that were born vaginally vs by cesarean section and found their gastrointestinal flora was different
Vaccination
Unable to cure many diseases but we can be vaccinated, vaccination is a means of priming the immune system so that it will quickly recognize an infectious agent and launch a response against it
- achieved by exposing the body to micro-organisms that are weakened or altered so that the vaccine will not give you the disease but will cause the immune system to mount a response
- response measured by antibody titer
Immunoglobulin
Also called antibodies, secreted by WBC in response to an antigen, binds to antigen and neutralizes it, short lasting immunity can be achieved by giving a person actual antibodies, the injected antibodies rather than the person’s own antibodies fight the disease
Direct contact
Direct physical contact between an infected individual and a host
Indirect contact
Person becomes infected through contact with contaminated object