Bacterial Disease Flashcards
What type of bacteria do you find in the small intestine?
Gram-negative
Give some examples of bacteria and viruses that use the upper respiratory tract as a portal of entry.
viruses - influenza parainfluenza rhinovirus measles varicella (chicken pox)
bacteria - streptococcus Streptococcus pneumoniae Streptococcus pyogenes Neisseria
Give some examples of intrinsic bacteria that can infect via the urogenital tract.
where do they come from?
E. coli
Klebsiella
Candida
the large intestine
Give some examples of extrinsic bacteria that can infect via the urogenital tract.
STIs
Chlamydia
Syphillis
Neisseria gonorrheae
HIV
Give examples of bacteria that can infect via broken skin.
main cause :
Staphylococcus aureus
Streptococcus pyogenes
State some consequences of infection via broken skin.
Abscess formation - pus filled pocket
Bacteraemia
Necrotic infection- piece of skin undergoes necrosis
myositus - infection spread deeper into the muscle and causes inflammation
Give some examples of bacteria and viruses and toxins that infect via the gastrointestinal tract.
virus - hep A, norovirus, hep E
bacteria - E coli, Shigella , Vibrio cholerae, Salmonella
toxins - enterotoxins
What are some consequences of infection via the gastro-intestinal tract?
Diarrhoea
Bacteraemia/systemic infections
What two main factors affect pathogenecity?
Infectivity and Virulence
Define infectivity.
influencing factors =
The ability of a pathogen to establish infection
factors influencing =
- transmission to host
- ability to colonise the host
- ability to find the unique niche
- ability to replicate
Define virulence.
The ability of a pathogen to cause disease
- toxins
- enzymes
- complete immune evasion
Define infectious dose.
Number of bacteria needed to cause infection
Describe how vibrio cholerae causes disease.
- It uses its flagella to propel itself into the mucosal membrane of the intestines.
- It then begins producing toxins A and B, which bind to GM gangliosides and triggers production of cAMP
- This leads to chloride efflux and hence movement of water into the lumen from the cells
State whether each of the following are Gram-positive or Gram-negative:
Shigella - negative Streptococcus - positive Listeria - positive Clostridium - positive Vibrio cholerae - negative E. coli - negative Salmonella - negative Staphylococcus - positive Neisseria - negative Haemophilus influenzae - negative
Give two examples of Gram-negative opportunistic bacteria.
Pseudomonas aeruginosa
Acinetobacter baumanii
Give two examples of Gram-positive opportunistic bacteria.
- E. faecalis
- Staphylococcus epidermidis
consequences of bacterial infection in the upper resp tract?
- pharyngitis
- tonsillitis
- sinusitis
what are consequences of lower resp tact infection ?
- Bronchitis
- Pneumonia
- Pneumonitis
what might happen if bacterial infection in the resp system spreads to adjacent tissues?
blood stream?
- brain abscess
- meningitus
- pericarditus
- Bacteriaemia
what might cause broken skin?
- surgery
- varicella
- eczema
- pressure sores
- injecting drug use
what are examples of bacteremia/ systemic infections?
- typhoid
- Listeriosis (very dangerous if it gets into the blood stream of old people)
- Salmonellosis
- septic arthritis
what is the pathogenicity of bacieteria?
the ability of a bacterium to cause disease
what are commensals?
- don’ t cause disease
what is the true pathogen?
- can cause disease in normal, healthy people
what is an opportunistic pathogen?
can only cause disease when they are given the
chance (if it’s given a leg up)
E.g. Staphylococcus epidermidis
what makes the infectious dose lower?
- if the pathogen can kill or subvert phagocytes then their infectious dose is lower
what factors influence virulence?
- Toxin Production
- Degradation of Host Molecules
- Interference with Host Cell Function
- Immune Evasion
which bacteria are transmitted by droplets?
- Tonsilitis
- Meningococcal sepcticaemia
- Neisseria meningitidis
