Bacteriology Flashcards
(37 cards)
What is Bacteriology?
The study of micro-organisms called bacteria, germs, or microbes
What is bacteria?
Bacteria are one celled vegetable microscopic organisms which exist in the air, on the ground, on our skin, in water, decayed matter, body fluids, on clothes, under nails, etc.
- they have both plant and animal characteristics
- a microorganism is an organism of microscopic to submicroscopic size
- some bacteria are harmful and some harmless
- some bacteria are carried by animals, humans, or insects. Others can be transferred by water, food and soil.
What are the two types of Bacteria?
- Pathogenic
- Non-pathogenic
- Pathogenic bacteria are harmful microorganisms that can cause disease or infection in humans when they invade the body.
These parasites require living matter for their growth, the minority of which are harmful and produce considerable damage by invading human and animal tissues
Pathogenic is also known as microbes or germs
Are classified into 3 main groups according to their cell shape
- Non-pathogenic
(Beneficial/ harmless)
- perform useful functions
- do not cause disease or harm
- it is found in yogurts, cheese & medicines
- constitute the majority of all bacteria
- beneficial in digestion and decomposing and improving the fertility of soil
What are the three classifications of pathogenic bacteria?
- Cocci - round
- Bacilli - rod shaped
- Spirilla - spiral/ corkscrew
Pathogenic bacteria: Cocci
Round shaped organisms which appear singularly or in groups.
3 classifications of Cocci
- think cocci has 3 c’s
A) Staphylococci - pus forming organism that grows in bunches or clusters.
(Boils, pustules, abscess)
- responsible for pilosebaceous infections
- Can live for 2 weeks on house hold surfaces
B) Streptococci - pus forming bacteria that grows in chains
- they cause blood poisoning and strep throat
C) diplococci - grow in pairs
- cause pneumonia
Pathogenic bacteria: Bacilli
- Rod shaped organisms
- the most common
- some can survive with or without oxygen
- cause diseases like tetanus, typhoid fever, tuberculosis & diphtheria
Spirilla
- curved or corkscrew
- divided into many groups
- most important is Treponema pollidum causing syphilis and chlamydia
Movement of bacteria
Cocci
- Rarely show active motility (self-movement)
- Are transmitted in the air, dust, or within the substances in which they settle
Bacilli and spirilla are both capable of movements and use hairlike extensions called flagella to move about
Bacteria growth and reproduction
- Bacteria consists of a outer cell wall and internal protoplasm
- Bacteria manufactures it’s own food through what they absorb around them
- give off waste products, grow and reproduce.
- the life cycle of bacteria consists of two phases
What are the two phases of a life cycle in bacteria?
Active phase & Inactive phase
Active phase/ Vegetative bacteria
- during this stage the bacteria grows and reproduces
- bacteria multiply best in warm, dark, damp, or dirty places
- in this environment they grow to their largest size and then divide into two daughter cells
- cell division may happen every 20-60 minutes
- as many as 16 million germs develop in half a day from one bacterium
- if conditions become unfavourable, the bacteria die or become inactive
Inactive or spore forming stage
Certain bacteria form spores with tough outer coverings to withstand long periods of famine, dryness and climate change.
Bacteria such as tetanus bacilli and anthrax coat themselves with wax like outer shells.
Spores can be blown about in the dust and not be harmed by disinfectants, heat or cold.
When favourable conditions are restored, spores change into the active form and begin to grow and reproduce.
Survival of bacteria (A,A,FA)
Aerobes: need oxygen to exist
Anaerobes: cannot survive or reproduce in the presence of oxygen
Facultative anaerobes: they change their method of survival and can adapt to conditions with or without oxygen.
When a disease spreads from one person to another, it is a..
Contagious or communicable disease
What is considered a good breeding ground for bacteria?
Warmth, moisture, and nutrition
Mucous membranes (mouth, nose, eyes, throat and ears) are natural breeding grounds for microbes
The body’s defence against bacteria
- Healthy skin is the first resistance
- the mucus areas have a disinfectant effect due to cilia or hairs in the nose or ears which act as mechanical cleaners
What is a local infection?
Confined to a particular part of the body
Indicated by a boil or pimple containing pus
Staphylococci bacteria is the most common
Some staph bacteria are resistant to treatments like antibiotics (MRSA)
What is a general infection?
Results when the bloodstream carries the bacteria and their toxins to all parts of the body as in blood poisoning or syphilis
Staph is responsible for food poisoning and a wide range of diseases (toxic shock syndrome)
Pus
Is a sign of infection/ bacteria
Consists of: bacteria, white blood cells (alive & dead) and proteins
The body defends itself by producing inflammation
Redness and swelling reveal an increase of body temperature and metabolic activity
The body then combats the infection through the action of white corpuscles and antibodies which destroy bacteria - which is called “phagocytosis”
How does the body defend itself?
The body produces antitoxins which counteract toxins produced by bacteria
Saliva and digestive fluids have an antiseptic effect the same as perspiration and other body secretions.
How can pathogens enter the body?
Break in the skin (cut, pimple) Mouth Nose Eyes Ears Unprotected sex
What are viruses?
A parasitic submicroscopic particle capable of infecting almost all plants and animals including bacteria.
Resides in the cells of a biological organism
Viruses are capable of replication only through taking over the host cell’s reproductive function
Viruses are hard to kill without harming the body’s own cells in the process
Vaccinations prevent viruses from growing in the body
Viruses cause the common cold, influenza, herpes, measles, chicken pox, hepatitis, polio, HIV.
What are bacteria?
One celled organisms that have both plant and animal characteristics
Some are harmful; some harmless
Difference between viruses and bacteria
Viruses can only live and reproduce by taking over the host of another cell
Bacteria can live on their own
Bacterial infections can usually be treated with antibiotics, but viruses are not affected by antibiotics.
Viruses are hard to kill without harming the body’s own cells in the process.
