Introduction to Medical Microbiology Flashcards
Where can you find infection?
Essentially everywhere. This can include: Intensive care General Practice Children Haematology and Oncology patients Hospital acquired infection (HAI)
State the categories of microorganism that cause disease
Bacteria Viruses Fungi Parasites Prions
State the sterile specimen types
Blood
Bladder
Cerebrospinal fluid (CSF)
Lung
State the non-sterile specimen types
Skin
Urethra
Nasopharynx
Gut
State what is meant by the term ‘sterile’
Containing no microorganisms
State the specimen type collected for bacterial culture:
Urinary tract infection
Mid-stream urine (MSU)
State the specimen type collected for bacterial culture:
Chest infection
Sputum
State the specimen type collected for bacterial culture:
Tonsillitis/pharyngitis
Throat swab
State the specimen type collected for bacterial culture:
Wound
Swab or pus
State the specimen type collected for bacterial culture:
Diarrhoea
Faeces
State the specimen type collected for bacterial culture:
Bacteraemia
Blood culture
State the specimen type collected for bacterial culture:
Meningitis
Cerebrospinal fluid (CSF)
Explain the role of microscopy and culture in the diagnosis of bacterial infection
Microscopy allows for the staining and rapid detection (not identification) of bacteria in a sample. However it is insensitive.
Culturing allows the bacteria to grow overnight on a specific medium. After incubation, the colonies are visible to the naked eye. Stains can then be identified by colonial appearance and growth patterns.
Unstained microscopy is done to view
Pus cells (Urine, CSF) Parasites (faeces)
Gram stain microscopy is done to view
Bacteria and yeast/fungi
ZN/auramine stain microscopy is done to view
Mycobacteria
State the type microorganism of that cannot be seen under the light microscope
Viruses
Describe gram staining and microscopy
It is rapid, NOT sensitive and cannot usually identify a particular species
Describe bacterial culture
It is slow, sensitive and the culture conditions are suitable for expected species
How do you identify a species?
Use observable characters (biochemical, morphological and physiological)
DNA based tests
Describe the methods of detecting viruses.
Virus can only grow/divide inside other cells/the host cell. Therefore a cell line must be inoculated.
Electron microscopy is used to due small size of viruses.
Antigen detection and nucleic acid amplification is more widely used to diagnose (serology less common)
Describe the diagnostic principles in parasitology
- Cell cultures rarely possible for parasites
- Serology can sometimes be useful
- Microscopy of different stages can help to understand the parasites easier
Describe basic infection control measures
Wash hands before touching patients/in between touching different patients.
Use of alcohol gel as well.
Swab stethoscope between patients
Wear plastic apron AND dispose when finished
etc
