Introduction to Medical Microbiology Flashcards
Name 5 microorganisms that cause disease
Bacteria Fungi Viruses Parasites Prions
From which sites can specimens be collected from and name some examples
Sterile Blood CSF Lung Bladder
Non-sterile Skin Nasopharynx Urethra Gut
Give examples of specimen types collected for culture
UTI – mid-stream urine (MSU) Chest infection – sputum Tonsillitis/pharyngitis – throat swab Wound or site of infection – swab or pus Diarrhoea – faeces Bacteraemia – blood culture Meningitis – cerebrospinal fluid (CSF)
What do unstained cells in microscopy enable us to see
Pus (e.g. urine, CSF)
Parasites (e.g. faeces)
What do Gram stained cells in microscopy enable us to see
Bacteria
Yeast/fungi
What do ZN/auramine stained cells in microscopy enable us to see
Mycobacteria
Describe the features of Gram staining
Rapid
Non sensitive (but highly sensitive)
Cannot normally identify a specific species
State some features of bacterial cultures
Slow
Sensitive
The culture conditions must be suitable for the expected species
What type of culture conditions should be considered in bacterial cultures
Media type
Atmosphere
Temperature
Duration of incubation
Name the different media types used in bacterial culture
Non-selective (e.g. blood, chocolate)
Non-selective specialised (e.g. mycobacteria)
Selective (e.g. MacConkey)
How can bacterial species be identified in a culture
By its observable characters (e.g. morphological, physiological, biochemical)
DNA based tests
What is the difference between sterile and non-sterile sites
Sterile sites should not have any organisms present
Non sterile sites have their own flora
What methods can be used to detect viruses
Molecular methods (e.g. real time PCR) Antigen detection Serology to determine immunity Electron microscopy Cell or tissue culture (inoculate a cell line)
What are parasites
Protozoa (e.g. malaria, amoebae, flagellates)
Helminths (AKA worms, e.g. roundworms, tapeworms, flukes)
Arthropods (e.g. lice, ticks, mites)
What diagnostic principles can be used in parasitology
Microscopy to identify the different stages such as parasites, cysts and ova in faeces or blood films in malaria
Serology is sometimes useful
