S1 Intro to Infection and Microbes Flashcards
What is an infection?
Invasion of a host’s tissues by microorganisms that can cause disease
What ways do people get infections?
- Source
- Intermediary (from the source)
- From themselves
- Animals
- Environment (from the source)
How can infections be transmitted?
- Contact (direct, indirect, vectors)
- Inhalation (droplets and aerosols)
- Ingestion
- Vertical transmission (mother to child)
How do microorganisms cause disease? (5 steps)
- Exposure
- Adherence
- Invasion
- Multiplication
- Dissemination
What determines whether an infection causes a disease?
- Pathogen - virulence factors, inoculum size and antimicrobial resistance
- Patient - site of infection and comorbidities
How do you determine if a patient has an infection?
- take a history - symptoms?
- examination - organ dysfunctions?
- investigations - specific and supportive
What are virulence factors?
‘Survival factors’ - improve the chances of reproduction
What are supportive investigations?
- full blood count - raised neutrophils, lymphocytes, etc?
- C-reactive protein
- blood chemistry - liver and protein function tests
- imaging
- histopathology
What are some examples of investigating bacteriology?
- take a specimen - swabs, fluids, tissues
- M, C & S - microscopy, culture, antibiotic susceptibility
- antigen detection
- nucleic acid detection
What are some examples of investigating virology?
- antigen detection
- antibody detection - patients response
- detecting viral nucleic acid
What are the four types of microorganisms causing disease?
- viruses
- bacteria
- fungi
- parasites
What are prions?
Protein particles (no nucleic acid)
Describe the general structure of a virus?
- Nucleic acid inside - either DNA or RNA
- Protein coat
- Envelope
- Spikes (for attaching to specific cell surfaces)
What is the Baltimore classification of viruses?
Viruses are classed dependent on type of genome e.g. DNA or RNA, single-stranded or double-stranded and the method of replication
What are the 3 classes of DNA viruses? Give an example of each
- Single stranded, non-enveloped - Parvovirus 19
- Double-stranded, non-enveloped - Adenovirus
- Double-stranded, enveloped - Hepatitis B
What are bacteriophages?
Viruses that infect bacteria
Could we use them as treatment?
What is the general structure of a bacteria?
- Nucleoid (circular DNA)
- Plasmids
- Ribosomes
- Cytoplasm
- Plasma membrane
- Cell wall
- Capsule
- Bacterial Flagellum
- Pili
What are the bacterial shapes?
- Coccus (Cocci)
- Spirillus
- Bacillus/Rods (Bacilli)
How can cocci be arranged?
Clusters e.g. staphylococci
or
Chains e.g. streptococci
What are the differences in oxygen tolerance in bacteria?
- aerobes
- obligate aerobes
- anaerobes
- obligate anaerobes
What is an obligate aerobe and anaerobe?
Aerobe - require oxygen
Anaerobe - require an oxygen free environment
How do you name bacteria, fungi, parasites? (Taxonomy)
Genus + species
What are the two types of fungi? Give examples
- Yeast (single-celled) - Candida albicans
2. Molds (multicellular) - dermatophytes (ringworm and athletes foot)
What are the two types of parasites? Give examples
- Protozoa (single-celled) - Giardia lamblia and plasmodium falciparum
- Helminths (worms, multicellular) - roundworms and tapeworms
