commensal bacteria vs pathogens

what is mutualism?

this is when both species are metabolically dependent on eachother and benefit from eachother.

give an example of mutualism in humans

e-coli in the gut benefits from the food but also helps derive certain vitamins like vitamin k

what is commensulism?

the species are not metabolically dependent on each other but the commensual benefits where the host does not gain anything

give an example of commensulims in human

staphyloccocus epidermis on the skin aka skin flora

what is parasitism?

when the parasite will harm the host

when can a commenusul become a parasite

when too much of there is present or if it moves to other areas

give examples of bacteria that can be found on the small intestines

lactobacilli and entrococci

give some examples of bacteria found in the large intestines

streptococcus, lactobaccilli, clostridia, staphylococcus

what does lactobaccilli do in the gut?

helps break down lactose into lactic acid whcih prevent the growth of harmful bacteria

what do kochs postualates determine?

determines whether something is pathogenic

what are virulence factors?

properties that pathogens have that allow it to cause disease and evade the immune system

how can pilli in bacteria act as virulence factors?

they allows binding of the bacteria to other cells or surfaces to allow adhesion and colonization of the host.

what is the definition of a disease?

when an infection produces symptoms

what is colonization?

when someone carries harmful pathogens without having symptoms

what bacteria can be found in the skin?

staphylococcus epidermis

what bacteria can be found in the oral/nasal cavity?

yeast, streptococci, neisseria

what bacteria are found in the small intestines?

lactobacilli and enterococci

what bacteria are found in the large intestines?

enterobacteria(e-coli), clostridia, bacteriods

why is lactobacilli important in female health?

Lactobacillus ferments glycogen producing lactic acid which helps maintain the acidic environment

what allows transmission of the pathogens

travelling through direct contact/indirect contact, dust borne through vectors and food, through air

what two way do pathogens allow adhesion and colonization of a host

through pilli which form peptide bond which allow binding to cells or surfaces although this is short lived

by formation of biofilms by releasing glycocalyx mucus which allow adhesion

how do bacterial cells allow the colonization of mucosal surfaces?

they produce protease enzymes that break down the cell epithelial

how do pathogen invade the host without being detected by the immune system

invade cells that are not phagocyctic and re arrange the cytoskeleton

what happens during pathogen invasion?

pathogen invades non phagocytic cells to hide it from the immune cell and rearranges the cytoskeleton of the cell

what are siderophores?

catechol and hydroxamates

why do cells secreted siderophores?

they will isolate and absorb any free iron and absorb it for growth and multiplication

why do bacteria cell release exotoxins?

kill host cells and release iron to absorb

what are the molecular version of kochs postulates

genes have pathogenic potential, and these are found in all strain in the pathogen. removing this genes will give avirulence. if a nonvirulent strain is given this gene it will become virulent. the gene produces an immune response.

describe the steps in acquiring disease from a pathogens

adhesion/colonisation, invasion, growth and multiplication, evasion of the immune system and exit strategy to transmit to the next host.( a cool indian got mad everyday)