Introduction to Medical Microbiology Flashcards
What are the 5 possible infecting agents?
Bacteria Viruses Fungi Parasites Prions
What is the specimen collection for a urinary tract infection?
Mid stream urine
What is the specimen collection for a chest infection?
sputum
What is the specimen collection for tonsillitis/pharyngitis
Throat swab
What is the specimen collection for the site of infection or a wound?
Swab or pus
What is the specimen collection for diarrhoea?
Faeces
What is the specimen collection for bacteraemia?
Blood culture
What is the specimen collection for meningitis?
CBS
What does unstained microscopy allow you to see?
Pus cells (urine, CSF) Parasites (faeces)
What does a gram stain allow you to see in microscopy?
Bacteria yeast and fungi
What does a ZN stain or an auramine stain allow you to see?
Mycobacteria (a bacterium of a group which includes the causative agents of leprosy and tuberculosis)
What infecting agent is not visible in light microscope?
Viruses
What is the difference in the function between gram stain microscopy and culture?
Microscopy is rapid, insensitive, can’t identify a particular species
Culture is slower, more sensitive and the conditions are suitable for the expected species
How is the species identified?
Observable characters - Morphological, physiological, biochemicla
DNA tests
Typing - determines the strain within the species
What are the sterile sites within the body?
Blood, CSF, Lung, Bladder
What are the non-sterile sites in the body?
Skin, Nasopharynx, Urethra, Gut
How are viral infections diagnosed?
Electron miscroscopy,
Cell or tissue culture
Antigen detection
Detection of cytopathic effect (structural changes in host cells that are caused by viral invasion)
Molecular methods including real time PCR
Serological to determine immunity (serology is the investigation of blood serum with regard to the response to an introduced pathogen or introduced substance.
§- What are the three different types of parasites?
Protozoa - malaria
Helminths (worms)
Arthropods - lice
§ - How can parasites be diagnosed?
Microscopy of different stages - parasites, cysts and ova
- blood films for malaria
Culture rarely possible
Sometimes serology is useful
Give some examples of healthcare acquired infection
Meticillin resistant Staph Aureus - MRSA
Clostridium difficile
Noroviruses
ESBL’s - Organisms with extended spectrum beta lactamases