Module 1: Sources and Prevention of Infection Flashcards
what is an endogenous infection?
infection gained from our own microbiota, common
what is an exogenous infection?
infection gained from another’s microbiota
what are fomites?
surfaces that can carry infectious organisms eg glass, door handles
what are zoonosis diseases?
infectious diseases that can be transmitted from animals to humans
what are some characteristics of the bacterial zoonotic infection Camplobacteriosis?
- acute onset of cramping, nausea, watery diarrhoea
- either stool containing blood or very watery
what are the four main virulence factors of Campylobacter bacteria?
- production of toxins that cause diarrhoea
- high mobility allows them to break through mucus layer of the gut
what does the cholera-like enterotoxin released from Campylobacter bacteria result in?
causes an overproduction of cAMP, leading to the efflux of sodium from intestinal cells, leading to watery diarrhoea
what does the cytolethal distending toxin released from Campylobacter bacteria result in?
produces DNase which eats DNA to cause cell death and leads to bloody diarrhoea
what do dermatophytes result in?
fungal infection that targets keratin stores in the human body (nails, hair, upper skin)
what is giardia?
intestinal protozoan parasite that can cause serious health issues
what are the two forms giardia can grow in?
- trophozoite
- cyst
how many giardia cysts are required to cause infection in a normal gut compared to an immunocompromised gut?
10-25 cysts, compared to 1-2 in immunocompromised
what is one significant effect giardia has on the intestinal epithelium?
blunts epithelial villi to reduce absorption leading to malabsorption and malnutrition
what are environmental pathogens?
organisms hat spend most their life outside of a host, but will infect a host if it meets it (opportunistic)
what kind of infection is Pseudomonas aeuruginosa?
bacterial
what are the virulance factors of Pseudomonas aeuruginosa?
- biofilms
- phagocyte invasion
- invasins
- toxins
what bacteria can cause dermonecrosis in burn wounds, corneal damage in the eye and lung damage?
Pseudomonas aeuruginosa
how can you tell if you have Pseudomonas aeuruginosa infection?
- blue pus in agar
- fruity odour
- beta hemolysis
how to treat a Pseudomonas aeuruginosa infection?
combination of broad antibacterial drugs
what kind of infection is Aspergillus?
fungal
what causes a Aspergillus infection?
the inhalation of spores leading to respiratory infections
what is Aspergillosis disease?
causes an allergy by the spores, causes bad skin reactions
what is Aspergilloma disease?
a fungal ball grows in the lung
what can Aspergillus do to your blood vessels?
cause them to erode
how to treat Aspergilloma?
antifungals work 60% of the time, otherwise surgery
how to treat Aspergillosis?
antifungals are ineffective, so surgery
what kind of infection is Cryptosporidium?
parasite
in mild cases, what can Cryptosporidium cause?
watery diarrhoea, abdominal pain and vomiting that lasts 2 weeks
in immunocompromised people, what can Cryptosporidium cause?
chronic diarrhoea for months to years, rapid dehydration, malnutrition, imbalances, death
how do TNFa and prostglandins cause diarrhoea in a Cryptosporidium infection?
increasing the intestinal permeability causing water loss
what are the 6 chains that make up the ‘Chain of Infection’?
- infectious agent
- reservoir
- portal of exit
- means of transmission
- portal of entry
- susceptible host
what is an infectious agent?
any organism that is capable of infection
what is a reservoir?
any place an infectious agent can survive
can humans be a reservoir?
yes
what is a portal of exit?
any means through which an infection can leave a reservoir
what is a mode of transmission?
how an infectious agent can get from an infectious agent to a susceptible host
what are the 4 main kinds of transmission?
contact, droplet, airborne or common vehicle
what is the contact form of transmission?
either direct or indirect contact with the infectious agent
what is the droplet form of transmission?
contact with a droplet that is large and travels a short distance of the infectious agent eg sneezing, coughing, talking
what is the airborne form of transmission?
small particles of the infectious agent that can travel a long way to infect people
what is the common vehicle form of transmission?
infection to a susceptible host through the use of a commonly used thing eg food, water, medications, blood donations
what is the portal of entry?
how an infectious agent gets into the host
what is a susceptible host
a person with lacking immunity or resistance of a potential pathogen
why do young kids get infections?
that have immunological immaturity
why do old people get infections?
they have immunosenscence
what is a hospital acquired infection (HAI)?
infections people gain after admission to the hospital that they showed no evidence of having before admission
what causes 40% of HAIs?
UTIs
what is the main cause of hospital-gained UTIs?
catheters
what causes surgical site infections?
infection in a surgical wound depending on the contamination level of the wound
what kind of infection is ventilator-associated pneumonia an example of?
lower respiratory tract infection
what causes most hospital-related bloodstream infections (BSI)?
a central venous catheter
what is a community acquired infection?`
infections contracted outside a healthcare setting or diagnosed BEFORE 48 hours of admission
what are the 3 main antimicrobial HAI and CAI?
- MRSA
- ESBL
- VRE
