Infections and Superbugs Flashcards
What are the different types of microorganisms?
- Bacteria
- Viruses
- Fungi
- Protozoa
- Helminths
Describe bacteria
- Prokaryotic DNA (no nucleus) and circular DNA
- Highly abundant
- Found in soil, water, plants and animals
Describe viruses
- Smaller than bacteria
- Obligate intracellular (cannot survive outside host)
- DNA or RNA- no replication mechanism
- Humans have 3000 genes and HIV has 10 genes
- They have a protein coat and maybe envelope- no nucleus
- Found in animals and humans
Describe fungi
- Eukaryotes
- Multi or unicellular
- Cell walls contain chitin
- Found in soil, animals and humans
Describe protozoa
- Eukaryotic, unicellular animals
- Motile
- Found in water and animals
Describe helminths
- Worms
- Eukaryotic parasites
- Found in soil water and animas
Define pathogen
Organism that causes or is capable of causing disease
Define commensal
Organism that colonises host but normally does not cause disease (symbiotic relationship)
Define opportunist pathogen
Microbe that only causes disease if host defence is compromised (i.e. vulnerable people)
Define virulence/pathogenicity
Degree to which a given organism is pathogenic (ebola and cholera have high virulence)
Define asymptomatic carriage
When a phone is carried harmlessly at a tissue site where it causes no disease (vaccination to reduce asymptomatic carriage)
Define pathobiont
Potentially pathological which lives as a non-harming symbiont
Define tropism
When an organism is able to attach itself to tissue
What are the different routes of acquisition and transmission?
- Skin
- Airway
- Alimentary tract
- Genital tract
- Inoculated into blood
What microbes can be transmitted via skin?
Bacteria, fungi, virus and helminths
What microbes can be transmitted via airway?
Bacteria, fungi and viruses
What microbes can be transmitted via alimentary tract?
(usually leads to diarrhoea)
Bacteria, viruses, helminths and protozoa
What microbes can be transmitted via genital tract?
Bacteria, viruses and protozoa
What microbes can be transmitted through inoculation into blood
Bacteria, viruses and protozoa
Describe bacterial nomenclature
Genus, species
What are current mega problems
HIV, malaria, tuberculosis, antibiotic-resistant bacteria, hospital associated infections, respiratory viruses, viral haemorrhage fever and Zika virus
What does flora mean?
Bacteria
What does a gram stain tell us about bacteria?
Blue- gram positive- thick cell wall made of peptidoglycan
Pink- gram negative- bacteria held together by lipopolysaccharide
Why are peptidoglycan and lipopolysaccharide harmful?
They are detected by the immune system because they are not found in animals, therefore they can cause sepsis
What are the two shapes of bacteria?
- Rods and cocci
- Cocci are small and round
- Rods can be spiral (spirochete) or curved (vibrio)
What is the Ziehl-Neelsen stain used for?
- Pink stain that tests for mycobacteria (genus that causes disease)
- Acid is added to sample and mycobacteria holds pink stain (acid fast bacillae)
What are the features of an ideal bacterial environment?
- Temperature- 80 (120 for spores)
- pH- 4-9
- Water- 2 hours-3 months (>50 years for spores)
- Bacterial growth is exponential
- Dislike UV light
What are endotoxins?
Component of the outer membrane of the bacterium
What are exotoxins?
Secreted proteins of gram positive and gram negative bacteria (e.g. tetanus toxin inhibits nervous system)
