CSI 3 hospital acquired infections Flashcards
What is meant by a reservoir
A reservoir of an infectious agent is the habitat where it normally grows e.g humans
Give some examples of diseases without intermediaries
STDs, measles, mumps
Why was smallpox eradicated after the last human case was identified and isolated
Humans are the only reservoir for the smallpox virus
What is a carrier when referring to a human
Someone who has no symptoms but can still capable of transmitting the disease to others
What is the difference between a carrier and a vector
A carrier is infected with the pathogen (even if they are asymptomatic) but a vector is not infected with it
What are 3 different types of carriers
Incubatory, convalescent and chronic
What is a incubatory carrier
Someone that can transmit the agent during the incubation period before chronic illness begins
What is a convalescent carrier
Those who have recovered from illness but remain capable of transmitting it to others
What is a chronic carrier
Someone that continues to harbour the causative agent for weeks or months after infection
What is zoonosis
Infectious disease that is transmissible under natural conditions from vertebrae animals to humans
Give 5 ways in which a pathogen can leave a host
Respiratory tract, urine, feces, crossing placenta from mother to foetus, cuts or needles in skin
Describe and explain the two modes of direct transmission
Direct contact - skin to skin and sexual intercourse
Droplet spread - coughing, sneezing in short range
Describe 3 ways of indirect transmission
Airborne transmission - when infectious agent is carried by dust or droplet suspended in air
Vehicles - food, water, blood or formites (inanimate objects)
Vectors - Mosquitoes, fleas and ticks
Give 3 examples of non specific factors that defend against infection
Skin, mucous membranes and gastric activity
How can vehiclebourne transmissions be reduced
Elimination or decontamination of vehicle
How can airborne transmission be reduced
Modify ventilation or air pressure, filtering or treating air
How can vectorbourne transmission be reduced
Controlling vector population e.g bug spray
Give 2 examples of interventions that aim to increase a Hosts defence
Vaccination, prophylactic use of antimalarial drugs
What type of intervention might prevent a pathogen from encountering a susceptible host
Herd immunity
What is a hospital acquired infection
An infection a patient gets whilst receiving treatment for medical or surgical conditions
What are the 4 main risks factors of HAIs
Medical procedures and antibiotic use, organisational factors, patient characteristics, behaviour of healthcare staff
How can HAIs be prevented
Increased compliance with and adoption of best practices of healthcare workers
What is a bacterial cell wall made of
Lipid bilayer and peptidoglycin matrix
What are the differences in cell walls between gram positive and negative bacteria
Gram positive - builds thick peptidoglycan sheath around a single membrane whereas gram negative builds a thin layer between two lipopolysaccharide membranes
What colour are gram positive and negative bacteria
Positive is purple
Negative is red/pink
When someone has an infection what are their WBC count, CRP levels and Respiratory rate like
All high
How does penicillin obstruct bacteria
It prevents peptidoglycan production so cell bursts due to osmotic pressure
How does penicillin prevent peptidoglycan production
It binds to serine on the penicillin binding proteins active site which inactivates the enzyme preventing it from forming a peptidoglycan matrix
How does MRSA evade certain antibiotics
It expresses penicillin binding protein 2a which has an altered active site which penicillin and other similar antibiotics cannot bind to
How can an antibiotic be inactivated
Enzyme degradation or alteration making it useless
How can bacteria evade beta lactam containing antibiotics
It can express a beta lactamase enzyme that breaks the beta lactam of the antibiotic making it useless
How can antibiotics overcome bacteria that produces beta lactamase
They contain beta lactamase inhibitors, allowing the beta lactam in the antibiotic to work normally
What is horizontal gene transfer
Where genetic material (plasmids) are transferred to another organism that isn’t its offspring
What is vertical gene transfer
Transfer of genetic information including mutations from parent to offspring
How can antibiotic resistance within one population of bacteria spread to another population
Horizontal gene transfer of antibiotic resistance or by vertical gene transfer from one generation to the next
What are antimicrobials
Drugs used to treat infections and disease caused by microbes
What are the two types of microbes treated by
Bacteria by antibiotics
Fungi by antifunguls
Where do you typically find antibiotic resistant DNA in bacteria
Plasmids
What gram of bacteria has an outer layer that protects it from their antibiotics
Drugs
Gram negative
How do germs get rid of antibiotics
Use pumps in their cell walls to remove antibiotic drugs that enter the cell wall
What other methods do bacteria use to get rid of antibiotics
Change or destroy antibiotics using an enzyme
Develop new processes that avoid the antibiotics target
Change the antibiotics target so it no longer does it’s job
What is sepsis
Body’s extreme reaction to an infection which can lead to tissue damage, organ failure and death
What is meant by shock
Inbalance in supply and demand
What is the sequence of septic shock
Hypotension > tachycardia > tachypnoea (high respiratory rate)
How are antibiotics delivered during sepsis
Intravenously as they have a faster delivery than oral antibiotics
