Introduction to bacteriology Flashcards
Who disproved the theory of spontaneous generation
Louis Pasteur
What was Pasteur’s Flask experiment
boiled meat broth in a flask, then bent the neck of the flask into an s shape - air could enter the flask by micro organisms could not, they got stuck in the neck, so therefore they did not generate from the broth
Koch’s postulates
- bacterium must be present in very case of the disease
- the bacterium must be isolated from the disease host and grown in pure culture
3.the specific ideas must be reproduced when a pure culture of bacterium is inoculated into a healthy susceptible host - the bacterium must be recovered from the experimentally infected host
Limitations to Kochs Postulates
normal bacterium can become a pathogen - when they gain access to deep tissue (surgery), gain extra violence factors, in immunocompromised patients
not all those infected or colonies be pathogenic bacterium will develop into a disease
some bacteria are a cultural in vitro
assumption that other host must have the same genetic makeup as the original host to react
What is a pathogen?
an organism that can invade the boast and cause disease
What is pathogenicity?
the ability to cause disease in another organism
What is virulence?
the degree of pathogenicity
Difference between colonised and infected
the host is colonies by bacteria
infection is the entry, establishment and multiplication of pathogens within a host
How to cause a disease
1) maintain a reservoir before and after infection
2) leave the reservoir and gain access to the new host
3) colonise the host
4) Harm the host
what does an infectious disease depend on?
the microorganism
the number of Bactria that enter the body/wound
the quality of the persons specific and non-specific body defences
what is the chain of infection
causative agent - transmission - host
examples of causative agent
pathogenicity
infectious dose
reservoir source
examples of transmission
contact
common vehicle
airborne vector
What is epidemiology?
The study of the determinants, occurrence, distribution and control of health and disease in a defined population
The host-parasite relationship can…
…determine the outcome of the infection
Non-specific defences
not directed at any particularly organism
Specific defences?
mediated by the host immune system and direct at a particular organism
what are the two types of specific defences?
Humoral and cell-mediated
Humoral defenses
due to specific antibody production
cell-mediated
due to T lymphocytes and the cytokines they produce
Non-specific defence
skin (barrier), Normal Flora (make is difficult for exogenous pathogens to invade), flushing effect (tears/urine/mucus remove organisms), gastrointestinal tract (low pH of stomach acid inactivates ingested viruses), Vaginal secretions (low pH due to lactobacilli protection from bacterial infection)
Phagocytosis - non-specific defence
Neutrophils - multilines nucleus and granules contain antimicrobial compounds - phagocytose and kill bacteria
Macrophages - large, granular cells - intimate inflammatory response and when activates are antibacterial
Complement proteins - non-specific defence
Opsonins - enhance phagocytosis - called opsonisation
What is complement
a comes of blood proteins produced in a cascade which becomes activated upon infection to enhance phagocytosis and lyse bacteria
