10. Opportunistic infection Flashcards
define opportunistic pathogen
an organism that can cause infection in individuals with abnormal host defenses
what is koch’s posutlate
specific criteria to decide if that particular pathogen is causing the specific disease
name 2 criteria from koch’s postulate
- the pathogen must be present in every case of the disease
- when the cultured pathogen is inoculated into a host, the specific disease must be reproduced
what disease has never been proven by koch’s postulate, why?
leprosy causing pathogens
too hard to culture
name 2 limitations of koch’s postulate
viruses are difficult to work with
polymicrobial infection = more than one pathogen
how many bacterial cells in the human body
10^4
what can trigger harmful alterations to gut flora?
antibiotic use as sensitive gut flora are killed
describe clostridium difficile:
- structure
- residence
- symptoms
- who is vulnerable
gram positive, rod-shaped, spore forming bacteria
reside in the gut
symptoms: diarrhoea, fever, loss of apetite
vulnerable: those on antibiotics, elderly, immunocompromised, live in healthcare setting
what toxin does C. difficile produce
A+ B toxin
- each subunit bound by peptide bond
define opportunistic infection
where the occurrence or severity of an infection is determined by patient, not microbial factors
give an example of a disease that is masked in healthy patients, but expressed in immunocompromised patients
leprosy is masked by good t-cell immunity
why is it problematic if a patient is placed on a ventilator
they become immunocompromised = offers new surface to be colonised by opportunistic pathogens
why are immunocompromised patients at risk
tend to be in healthcare settings = making them more vulnerable to resistant pathogens
why does splenic function also determine infection
the spleen acts as a filter on the blood (clears bacteria), if this function is reduced, then the host will become susceptible
what is the mortality rate for post-splenectomy sepsis
50-70%
