Introduction to Medical Microbiology Flashcards
Name the categories of micro-organisms that can cause infection
Bacteria
Fungi
Parasites
Prions
Viruses
What are the types of specimen samples collected for culture?
Blood culture
Cerebrospinal fluid
Faeces
Midstream urine
Throat swap
Pus
What is the specimen collection for a urinary tract infection?
Midstream 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 bacteraemia?
Blood culture
What is the specimen collection for meningitis?
CBS
How is microscopy used in medical microbiology?
Microscopy is the most common method used both for the detection of microorganisms directly in clinical specimens and for the characterization of organisms grown in culture
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
Fungi
Yeast
What does a ZN stain or an auramine stain allow you to see?
Mycobacteria
What is mycobacteria?
A bacterium of a group which includes the causative agents of leprosy and tuberculosis
What infecting agent is not visible in light microscope?
Virus
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 can a species identified?
Observable characters - Morphological, physiological, biochemical
DNA tests
Typing - determines the strain within the species
What are sterile sites of the body?
Areas typically where microorganisms are not found and are often places deeper in the body and more protected from outside infection.
What are examples of sterile sites in the body?
Blood
CSF
Pleural fluid
Pericardial fluid
Bone and bone marrow
Joint fluid
Bladder
What are non-sterile sites in the body?
Non-sterile sites are areas where microbes are often found and are usually more accessible from the environment.
What are examples of non-sterile sites of the body?
Skin
Nose and airways
Stomach and intestines
Mouth and teeth
Genitals
Name methods of detecting viruses
Electron microscopy
Cell or tissue culture
Antigen detection
Detection of cytopathic effect
Molecular methods including real time PCR
Serology to determine immunity
What is serology?
The investigation of blood serum with regard to the response to an introduced pathogen or introduced substance.
What are cytopathic effects?
Structural changes in host cells that are caused by viral invasion
What is a parasite?
A parasite is an organism that lives on or in a host and gets its food from or at the expense of its host. Parasites can cause disease in humans.
What are the three different types of parasites and give an example of each?
Arthropods - Lice
Helminths - Worms
Protozoa - Malaria
How can parasites be diagnosed?
Microscopy of different stages - parasites, cysts and ova
Blood films for malaria
Culture rarely possible
Sometimes serology is useful
What are examples of healthcare acquired infection?
MRSA
Clostridium difficile
Noroviruses
ESBL’s - Organisms with extended spectrum beta lactamases
What are basic infection control measures?
Hand hygiene.
Use of personal protective equipment (e.g., gloves, masks, eyewear).
Respiratory hygiene / cough etiquette.
Sharps safety (engineering and work practice controls).
Safe injection practices (i.e., aseptic technique for parenteral medications).
Sterile instruments and devices.
What is a microbe?
A living thing that is too small to be seen with the naked eye. Must use a microscope to see it.
What are the different microbes?
Viruses - smallest
Bacteria
Fungi - largest
Are all microbes bad?
No - gut bacteria include good microbes, aid in digestion and help us absord all nutirents from our food
What is an infection?
When microbes grow in the wrong place
What is a pathogen?
A microbe that causes an infection
What is an example of a prokaryote organism?
Bacteria
What is an example of eukaryote organism?
Fungi
What is one big difference between prokaryote and eukaryote cells?
Eukaryotic cells are much bigger
Are prokaryotic and eukaryotic cells unicellular or multicellular?
Prokaryotic - unicellular
Eukaryotic - uni or multicellular
Where can viruses replicate?
Only in the living cell of an organism
What can be found in the centre of a virus?
Genetic material - concise but enough of it for the virus to carry out its function - to replicate inside living host
What is the role of the caspid?
A protein shell, surrounds the genetic material - providing protection to living material
What is the role of the viral envelope?
Protecting the RNA or DNA molecule(s), evading recognition by the immune system, and facilitating virus entry.
