Microbiology Flashcards
Define the term microbiology
The science of microorganisms (any organism too small to be seen by the naked eye)
What are the 4 basic groups of microbes which can all cause healthcare associated infections?
- bacteria
- viruses
- fungi
- protozoa
What is the structure of a prokaryotic (bacteria) cell?
-has no distinct nucleus
-genetic information stored in plasmids and singular chromosomes
Give 3 examples of common bacterial infections
-salmonella
-E.coli
-MRSA
What are the nutritional requirements that bacteria cells need?
-food
-water
-carbon dioxide
-neutral or alkaline conditions
-obligate aerobes (require oxygen for aerobic respiration)
What are the 3 basic shapes that bacteria are classified into?
- coccus (circular)
- rod or bacillus
- spiral (spirochete)
What are the 4 types of coccus bacterium?
- single coccus
- paired coccus (diplococcus)
- chains or streptococcus
- bunches or staphylococcus
Give 3 examples of fungal infections
-thrush
-athletes foot
-aspergillus
What is the structure of viruses?
Have either DNA or RNA but never both, contained within a capsule
Give 3 examples of viral infections and state the tissues that they infect
(can only replicate inside a living cell)
-cold virus = upper respiratory tract
-influenza virus = upper respiratory tract and lungs
-chicken pox = nerve endings
What are the 3 ways that virus’ effect the host cells?
- infecting the cell and killing it
- has no effect but remains potentially infectious
- transformation of cell into malignant form
What is the microorganism protozoa?
A unicellular microbe which inhabits mainly soil and water which can cause severe disease
Give 3 examples of protozoal infections (with detail)
-malaria (plasmodium malariie infects and destroys RBC)
-cryptosporidium (from infected drinking water causing diarrhoea & fever)
-amoebic dysentery (from entamoeba histolytic from infected drinking water)
What is pathogenesis?
The development of a disease
What 3 things does pathogenesis do to humans?
- disruption to tissues
- production of toxins
- produces large and harmful immune responses from the body
What 5 things determine the virulence (severity) of a disease?
- invasiveness of the bacteria (its ability to invade tissues and multiply rapidly)
- toxigenicity of the microorganism
- its immunogenicity
- how good the organism is at evading the immune system
- its ability to live outside the body and survive transport
What evidence may a human display showing that they have an infection?
-a fever (38 degrees +)
-pain
-discharge of pus or other bodily fluids
-increase in white blood cells
-loss of function
-general malaise (discomfort)
-inflammation response (pain, swelling, heat, redness)
What actions do antibiotics bring about in a bacterium cell?
-block metabolism
-block DNA replication
-block protein synthesis
-inhibit cell wall synthesis
What is the name of the process in which bacteria reproduce rapidly?
Binary fission
How can antibiotic resistance occur?
-bacterial transformation (resistant gene passed on)
-conjugation (resistant gene directly given)
-transfection (type of plasmid transformation)
-spore formation
What are antiviral agents and how do they work?
-as viruses use human cells in order to function it is hard to find drugs which target the virus without harming other human cells
-some drugs exploit the fact that the virally infected cell produce some unique enzymes in order to produce new virus particles
-drugs include interferon and AZT
What are antifungal agents and why are they rarer and more toxic to the host?
-fungal pathogenicity occurs because the fungi disrupt tissues or cells, produce toxins or create large and harmful immune responses
-fungal cells are similar to human cells therefore drugs are rarer and more toxic
-e.g clotrimazole
What does a commensal relationship mean?
one organism living in close association with another, such that one organism benefits without harming the other
