Infection Flashcards
what are the 6 chains of infection
infectious agent reservoir portal of entry portal of exit transmission susceptible host
give an example of an endotoxin and exotoxin
endotoxin - lipopolysaccharide wall
exotoxin - proteases
what is a fomite
an area that a microbe can survive between reservoirs - keyboards, worktops
what is the incubation period and what is the relevance
where a person is infected but not showing clinical symptoms - dont realise they are. a long incubation period allows for more transmission
what is colonisation
where a patient has high levels of the microbe but is showing no signs of infection. no symptoms or clinical onset - staph aureus in nose
what is the difference between an endogenous and exogenous infection
endogenous - infectious agent comes from within, just in a different place - mutans in pulp
exogenous - infectious agent comes from an external source
what is the RO
risk of transmission, if 1 case can cause 1 case - high risk of transmission, likely to cause an outbreak
describe hepatitis A
RNA virus, lives in contaminated water, transmission via faecal-oral route - seafood can be contaminated. causes an acute infection, more common in developing countries
how can hepatitis A be detected
serology - antibodies (if enough time has passed since infection) or antigens
or antigens detected in faeces
what is the viral load
number of viral particles per ml of blood - high suggests highly transmissible
what is the viral structure of hepatitis B
double stranded DNA genome, protein coat with surface antigens, a core antigen beneath the surface
what are the 3 main routes of transmission of hepatitis B
blood borne - intravenous drug user, healthcare worker
sexual - homo and hetero
mother to baby
why is hepatitis b concerning in a baby
more likely to cause chronic disease - cirrhosis or liver cancer
what is the difference in disease in hepatitis b in endemic and non-endemic areas
endemic - acute disease mainly, with recovery - only 5% of chronic disease
non-endemic - common in children and 95% have chronic disease
describe hepatitis C
RNA virus, blood borne from human flavivirus, no vaccine available but effective treatments, subclinical infection can result in chronic disease - 60%
how is hepatitis D a defective virus
can only replicate protein coat if hepatitis B is present
what is the difference between co infection and super infection
co-infection - infection of hepatitis b and d at same time
super infection - hepatitis b infection, then get d infection
explain the virology of HIV
RNA virus, enters cells and converts to DNA. Then everytime the cell replicates, DNA replicates and proteins made. these can be released to then infect more cells. infects CD4 cells - reduces numbers, less able to fight infections
describe the primary infection of HIV
virus enters CD4 cells and reduces numbers - may have flu like symptoms
describe the latent infection of HIV
body is managing to control the virus, dont realise you have it for 2-15 years. control is lost, allows CD4 numbers to drop and patient to develop more infections
what infections are indictive of HIV
kaposi’s sarcoma, candidiasis, hairy leukoplakia, non-hodgkin lymphoma
what does HIV cause
acquired immunodeficiency syndrome
how is HIV transmitted
blood transfusion, IV drug user, unprotected sex
what is HIV PrEp
pre-exposure prophylaxis, given to HIV negative patients who are high risk for catching HIV, keeps virus from establishing a permanent infection
what is the aim of treatment of HIV
reduce viral load to stop developing AID
who are high risk individuals for HIV
sex workers, IV drug users, gay men
define sepsis
organ dysfunction due to excessive inflammatory response to infection
what differentiates sepsis from an infection
organ dysfunction
what is SIRS
systemic inflammatory response syndrome - high or low body temperature, increased respiratory rate, increased heart rate, increased white blood cell count
why can SIRS not be used alone to diagnose sepsis
it doesnt account for organ dysfunction, just systemic inflammation and at risk for sepsis
what is used to diagnose sepsis
SOFA - involves lab tests but can do a quick one - a score higher than 2 suggests sepsis - need medical intervention
reduced blood pressure, increased respiratory rate and a score of less than 15 on Glasgow coma scale
what is the difference for those with a pre-existing organ condition on the qSOFA
they start at a score of 1 already - only need 1 more thing to suggest sepsis
what is the glasgow coma scale
measures motor response, verbal response and eye response - fully working is 15, anything lower than this requires intervention
what causes sepsis
any infection. some are more virulent so more likely to cause infection - LPS
some people are more susceptible - immunosupressed
describe the pathophysiology of sepsis
tissue damage - cytokines and chemokines - increase vascular permeability - macrophages enter area
fail to resolve damage or infection - increase of cytokines - more tissue damage - failure to localise infection - hyperinflammation
also have suppression of immune response - apoptosis, dysfunctional dendritic cells - removal of b and t cells
results in organ dysfunction
why is sepsis important in dentistry
dental infection has ability to become systemic and cause sepsis, dentist can notice symptoms of disease
what is spoulding’s classification
classifies surfaces and determines what level of disinfection is required
what are the classifications of spoulding
critical - enters normally sterile surfaces, periodontal scaler or forceps. requires sterilisation
semi-critical - enters intact mucous membrane, handpiece or mirror - high level disinfection
non-critical - enters intact skin, light cure - low level disinfection
minimal risk - not in contact with intact skin - dental chair - low level disinfection
what are the different surfaces in dental setting
housekeeping surfaces - not normally in contact during procedure, require low level disinfection - walls, floor
clinical contact surfaces - in contact, either direct or via aerosol, splatting or dentist gloved hand - drawer, worktops
what is the difference between detergent and disinfectant
detergent - dont know efficacy, how well it actually works
disinfectant - kills all bacteria, only leaves spores, but requires contact time
what is the difference between a microbiome and a biofilm
microbiome - collection of microbes in the human body
biofilm - microbes on one surface, not everywhere has one - gut and oral cavity
skin has microbiome but not biofilm
what are some examples of microbes being introduced to the human body
giving birth - naturally, through birth canal, baby accumulates several bacteria
lactation - breast milk, contains sugars that bacteria can feed off
weaning off milk to solid food
why do we require microbes in the body
production of vitamins - k and b12
to prevent colonisation of more harmful bacteria - competes for resources and prevents attachment of c diff for example
stimulates cell growth
what are firmicutes
bacteria that have been linked to obesity. may have something to do with how energy is sourced from food - more firmicutes, more over weight
how could firmicutes be used in treatment
may be useful to do a faecal transplant - remove firmicutes from gut microbiome and may reduce obesity - change the way they store energy
how can the biofilm contribute to oral disease
some people have a biofilm composed of more sacchrolytic bacteria - thrive off of carbohydrates and acid producing - they are more likely to develop caries if their oral hygiene is poor - develops quicker
what biofilm is protective of caries
proteolytic - bacteria doesnt produce as much acid so more protective. however, is more indicative of periodontal disease. if their oral hygiene is poor - more likely to develop perio disease
what are the two ways in which microbial growth can be controlled
physical - heating up in hot temperatures its kills microbes - autoclave
chemical - disinfectant or anti septics
what is the difference between antiseptic and disinfectant
disinfectant has a high concentration of chemical to kill microbes on surfaces. anti-septics are used to target microbes and protect hosts, used on skin and mucous membranes
what are the mechanisms of action of disinfectants and antiseptics
target proteins or enzymes - functionality
target membrane to cause lysis - alters osmolarity
target processes - oxidising agents
give an example of a disinfectant/antiseptic for each mechanism of action
chlorohexidine - alters osmolarity
iodophor - denatures proteins
hydrogen peroxide - oxidising agent
what are the mechanisms of action of antibiotics
target protein synthesis
target dna transcription
attack cell wall
how do antibiotics target protein synthesis
by binding to ribosome subunit, inhibiting it and preventing protein building - tetracyclin
how do antibiotics attack cell wall
penicillin - attacks cross linking of peptidoglycan, causes it to fall apart. cell membrane then exposed - osmosis altered and cell lysis
how do antibiotics inhibit dna transcription
by inhibiting dna gyrase - dna cannot unwind for transcription
how can resistance to antibiotics develop
misuse of antibiotics - not finishing courses, taking them when not required. antibiotics work in a specific way - can change the shape of ribosome and antibiotic is no longer effective. or sometimes it is just thrown back out by cell
why might we want to manipulate the immune system
to promote a response - vaccines, immunosupressed
to suppress a response - autoimmune disease, chronic inflammation
what are the 5 stages of an infectious disease
pre-vaccine, vaccine coverage, loss of confidence, resumption of confidence, eradication
what diseases have a vaccine
polio, diptheria, hep B, measles mumps and rubella
what is the aim of a vaccine
stimulate an immune response, resulting in the production of IgG antibodies, providing immunological memory and immunity in a second exposure
what are different types of vaccine
live attenuated, inactive, subunit
what is a live attenuated vaccine
the infection has been genetically modified to make it weaker, injected and can replicate in tissues. generates a strong immune response but can result in disease in the immunosupressed. MMR
what is an inactive vaccine
the microbe has been killed before injection, cannot replicate in tissues. much safer but not as good immunity, may require several rounds - polio
what is a subunit vaccine
when parts of the microbe are taken and injected - proteins e.g. - hepatitis b
what can be added to a vaccine
adjuvant - intra muscular, forms a granuloma, keeps the vaccine at the site of injection, prevents it from being dispersed - increase immune response
what are the considerations for a caries vaccine
strep mutans has been severely linked - could vaccinate against this so it is removed from oral environment. but thought more the interaction of host and bacteria causes disease, not kosch’s postulate. also completely preventable and not life threatening
what drugs can be used to suppress immune system
corticosteroids, non-steroidal anti-inflammatory, methotrexate (disease modifying anti-rheumatic drugs)\ and biological therapy - anti tnf’s
what treatment is normally given for rheumatoid arthritis
methotrexate, but normally start to develop resistance so biological therapy is used in conjunction
