5 - medical microbiology Flashcards
How can viruses be classified?
- Type of Nucleic Acid they contain
- Shape
- Whether it has an envelope or not
- Mode of replication
How is the species of a virus identified?
- using antibodies to certain features
- PCR amplification of viral DNA
How can bacteria be classified?
By practical characteristics (such as size, shape, type of respiration, type of reproduction and immunologic properties) or staining properties (gram positive/negative)
How can specific species or variants of bacteria be identified?
- different immunologic properties
- specific antibodies
What are the main aims of medical microbiology?
- identify micro organisms within a specimen (to identify disease)
- identify antimicrobial susceptibility
- detect microbial products
- analyse a patient’s response
How do pathogenic fungi cause disease?
They release enzymes which digests external material
What precautions need to be carried out when collecting a microbial specimen
- specimen needs to be taken at the correct time in disease, before antimicrobials have been administered
- sterile containers and appropriate transport media should be used
- avoid contamination
- don’t use histological fixatives (kills the microbes)
- label accurately
Why does transport of a microbial sample to the lab have to be quick?
Some contaminants (such as environmental pathogens) May grow quickly and mask the presence of a pathogen or give a false impression of the balance between species
Why are most microbial samples refrigerated?
It prevents multiplication of most bacteria
What are some quick diagnostic techniques used in medical microbiology?
- microscopy
- antibody response in patients blood
- PCR and oligonucleotide probes to identify specific gene sequences
What are opportunistic infections?
Infections that effect people with weakened immune systems, but don’t normally effect those with functioning immune systems
Give some examples of acute infections
Influenza and E.coli infections
Give some examples of chronic infections
HIV, HPV and tuberculosis
Why do micro-organisms rarely cause disease
Humans have very effective physical and immune defences that are difficult for pathogens to evade
What is pneumonia?
An infection in the lungs (caused by a wide range of pathogens) that causes an interference in air exchange in the lungs
