An Introduction to Medical Microbiology Flashcards
What are possible infecting agents?
Bacteria
Viruses
Fungi
Parasites
Prions
What are the two areas of the body in terms of organisms?
Sterile and non-sterile
What is a sterile site?
One which normally does not have infection
What is a non-sterile sites?
One which has some degree of harmless infection, usually associated with the outside world
What are examples of sterile sites?
Blood
Cerebrospinal fluid (CSF)
Lung
Bladder
What are examples of non-sterile sites?
Skin
Nasopharynx
Urethra
Gut
Which kind of sites is easier to diagnose a harmful infection?
Sterile sites because you are not expecting to find anything there
What are some common speciments collected for bacterial culture?
Mid-stream urine (urinary tract infection)
Sputum (chest infection)
Throat swab (tonsillitis)
Swab or pus (wound or site of infection)
Faeces (diarrhoea)
Blood culture (bacteraemia)
Cerebro-spinal fluid (meningitis)
What are different ways of looking for pathogens?
Microscopy
Gram stain and microscopy
Bacterial culture
In what site does microscopy work well?
Sterile sites but not non-sterile sites
What can microscopes not see?
Viruses, they are too small
What can unstained microscopy see?
Pus cells (in urine)
Parasites (in faeces)
What is stained microscopy used to see?
Yeasts
Fungi
How can flourescent bacteria be seen?
By using flourescent staining such as auramine. such as for mycobacteria
What does gram staining identify?
Whether the bacteria is gram negative or gram positive
How does gram negative bacteria appear when gram staining?
Pale red
How does gram positive appear when gram staining?
Dark purple
What is an advantage of microscopy?
It is quick
What can gram staining not identify?
The specific speices present
What does gram staining not being ‘sensitive’ mean?
There needs to be lots of bacteria present for it to work
What are properties of bacterial culture?
It is slow
It is sensitive (do not need lots of bacteria)
What can be changed in a bacterial culture?
Culture conditions to promote the growth of certain species
What are things that can be controlled in a bacterial culture?
Type of media (selective/non-selective)
Atmosphere
Temperature
Duration of incubation
What are observable characteristics that can be used to identify a species?
Morphological
Physiological
Biochemical
What distinguishes strains within a species?
Typing
How can viral infections be diagnosed?
Molecular methods (such as real time PCR)
Antigen detection
Serology
Electron microscopy
Cell or tissue culture
What is not really used now for detecting viruses?
Electron microscopy
Cell or tissue culture
What is serology?
Detecting antibodies that the patient has produced against the virus
What are the 3 classes of parasites?
Protozoa
Helminths (worms)
Arthropods
What are examples of protozoa?
Malaria
Amoebae
Flagellates
What are examples of helminths?
Roundwormm
Tapeworm
Flukes
What are examples of arthropods?
Lice
Ticks
Mites
What is normally used to diagnose parasites?
Microscopy
What is looked for when diagnosing parasites?
Parasites
Cysts
Ova
What is rarely possible and what is sometimes useful for diagnosing parasites?
Culture is rarely possible and serology is sometimes useful
What is a healthcare acquired infeciton?
An infection that is acquired in a hospital or other healthcare facility
What are examples of common healthcare acquired infections?
MRSA
Clostidium difficile
B-lactamases
Noroviruses
What is antibacterial resistance?
The ability of a microbe to resist the effects of medication that once could successfully treat that microbe
What are we currently experiencing in terms of antibiotics?
A discovery void
What are examples of basic infection control?
Wash hands before touching the patient
Wash hands between patients
Swab stethoscope between patients
Isolate infectious patients in single rooms
