Unit 3 Flashcards
1
Q
What is the chain of infection?
A
- reservoir of infectious organism
- suceptible host with portal of entry of reasonable possibility
- mode of transmission
2
Q
What is a susceptible host?
A
- naïve host
- no strong memory of pathogen
3
Q
What are the types of reservoirs?
A
environmental (soil and water)
non-human animals
infected/ colonized humans
4
Q
What is maintenance?
A
how pathogen survives in resovoir
5
Q
How can a pathogen survive in a reservoir?
A
- infects/ colonizes animals and spread animal to animal
- infects/ colonizes humans and spreads humans to humans
- grows using resources and environment
6
Q
What are the methods of transition?
A
vectors and fomites
7
Q
What is a vector?
A
living organism that can transmit pathogens between humans and animals or humans
- typically blood sucking insects
8
Q
What are fomites?
A
inanimate objects for pathogens to go host to hose
- the more stable the environment the better this works
9
Q
What are the three modes of vectors?
A
- direct
- indirect
10
Q
What are direct vectors?
A
person to person
animal to person
droplet
11
Q
What is droplet transmission?
A
- large drops (larger than 5um)
- when an infected person coughs, sneezes, or talks
- 3-6ft transmission
- large droplets don’t circulate in air
12
Q
What is indirect transmission?
A
- reservoir to new host with no direct contact with infected person
- fomite
- common vehicle
- airborne
13
Q
What is a common vehicle transmission?
A
- pathogen transmitted y a common inanimate vehicle to multiple cases
- typically food or water
14
Q
What is airborne transmission?
A
- droplet nuclei form when fluids of droplets are evaporated enough to remain airborne for prolonged periods
- droplet nuclei are less than 5um
- droplet nuclei could be inhaled by someone who has never had contact with person who expelled it
15
Q
What is the route of transmission?
A
how microbes enter and exit the body
16
Q
What are the routes of transmission?
A
- fecal oral
- horizontal
- vertical
17
Q
What is horizontal transmission?
A
transmission from one person to another
18
Q
What is vertical transmission?
A
- from mom to fetus or neonate
- placental
- maternal- parturition (birth)
- maternal - neonate
- torch pathogens
19
Q
What are the pathogens with multiple modes of transmission?
A
- anthrax
- plague
20
Q
What is anthrax?
A
- environmental reservoirs
- can get directly from reservoir or from infected animals
- spores can enter through inhalation or through skin breaks
21
Q
What is the plague?
A
- animal reservoir
- vector borne or respiratory droplets
22
Q
What is public health?
A
- science of protecting and improving the health of people and their communities with the focus on populations not individuals
23
Q
What does public health do?
A
- uses population based research to:
- develop educational programs
- make policy recommendations
- administer services through the community
- plays a role in detecting, preventing, responding to infectious diseases
24
Q
What are the levels of public health?
A
- local (county)
- state ( NC DHHS)
- federal ( US DHHS)
- international (WHO)
25
How can public health be effective?
mandates and routine control measures
26
What do mandates do?
- protect populations from disease
- establishes procedures that if followed propperly will stop the spread of disease
- could be legislative, typically at the state level
27
What are examples of routine public health measures?
- chlorination, water sanitation, waste treatment, food supply inspections, immunizations, isolation orders
28
What does herd immunity do?
- breaks the chain of infection
- only applicable to human to human transmission
29
What are the determinants of transmission efficacy?
- pathogen shedding (duration, amount, route )
- exit needs to facilitate next entry
- the higher the transmission efficacy the more people must be vaccinated for herd immunity
30
What is the difference between quarantine and isolation?
- isolation is for infected people and quarantine is for exposed people
31
What is descriptive epidemiology?
- studies patterns, sources, spread, frequency of disease populations
- produces data for public health departments
32
What does descriptive epidemiology do?
- studies include evals on factors that:
- lead to infection
- affect transmission
- associated with clinical disease and diagnostics
- the collection of data associated with disease related to person place and time
- describes imporant charecteristics of disease like geographical or populations affected
- not intended to make comparisons across a population
33
What does descriptive epidemiology do?
- case reports and series
- ecological studies
- surveillance data
34
What are the uses of descriptive epidemiology?
- determine magnitude of problem
- determines geological distribution of illness
- detect epidemics
- evaluates control measures
- monitor changes in infectious agents
- facilitates planning
- tracks healthcare associated infections
35
What are case reports/ series?
- detailed reports of signs, symptoms, diagnosis and treatment of individual patient
- typically used to describe an unusual/ novel occurrence
- anecdotal evidence due to methodological limits can be useful in recognition of new diseases or unexpected adverse effects of treatments
- first way a new diagnosis is reported / publicized
36
What is incidence?
- a number of new infections given during a time frame
- provides info on disease acquisition and transmission
37
What is prevalance?
- the number of people with a disease at 1 time
- vital for informing public health practice
- could be similar or different from incidence
38
What is mortality?
- the number of people who died from a disease
39
What is fatality?
- the number who were infected who died from a disease
40
What is the rate of disease?
- percent of the population infected
- in x per x
41
What is the rate of incidence?
number of new cases / number of people in the population
42
What is an endemic disease?
- expected / baseline
43
What is an epidemic?
- the number is higher than normal
- a breakout
44
What is a pandemic?
- worldwide epidemic
45
Can a disease have multiple classifications during a year?
yes
46
What is analytical epidemiology?
- designed to test a hypothesis and draw conclusions about the cause of a disease or the risk factors involved
47
What does analytical epidemeology include?
- case control studies
- cohort stdies
- randomized clinical trials
48
What do case control and cohort studies do?
- studies human habits and exposures
49
What are the pros and cons of randomized clinical trials?
- only one with true control and testing groups
- most expensive
50
What is a target?
who you want to make inferences
51
What is the source?
- the subset of target we can actually study
52
What is the study?
- the individuals from the source that actually contributed to data to study
- you want study to be similar to target
- avoid confounding variables and bias
53
What are case control studies?
- compare exposure characteristics of cases with a representative sample of target population controls
- retrospective study
- want to keep cases and controls as similar as possible
- done before cohort studies
54
Who are the controls in case control studies?
people with no disease
55
What are the differences between case control studies and cohort studies?
- case control is typically done first
- case control is typically smaller and less expensive
56
What is a cohort study?
- tends to be prospective but could be retrospective
- follows a group of people overtime
- base on exposure, occupation, genetic trait, geographic location
- best for disease with high incidences among exposed populations and exposures with high prevalence in source population
57
Sum up cohort study vs case control study
- cohort studies compare exposed people and non exposed people for future
- case control study compares people with disease and people without the disease,looks into the past
58
What is relative risk?
- ratio of incidence in exposed vs unexposed to have disease
- mainly in cohort and clinical trials
59
What is the relative risk formula?
- (A/ (A+B) ) / (c/(c+d) )
- if greater than 1 the exposed are more likely and if below one there is something providing protection
60
What is the odds ratio?
- used to examine distribution of exposures between cases and controls
61
What is the odds ratio formula?
- odds of exposure among cases / odds of exposure among controls
62
How are epidemics detected?
- with descriptive epidemiology
- clinical micro labs identify infectious agents
- adaptive surveillance (monitoring of sentinel sites)
- case reports when clusters of cases recognized
63
What kind of data do clinical micro labs identify?
- mandatory reportable disease (national notifiable diseases)
- gps and demographic info (geographic)
64
Why should you investigate epidemics?
- not every case is investigated (like the routine ones with set precautions)
- determines an intervention to end the outbreak
- learns lessons to create new control measures and prevent future outbreaks
- identifies new or unusual disease agents (emerging pathogens) or previously unrecognized sources of disease
65
What are the steps to epidemic investigations?
1. verify diagnosis and confirm outbreak (more cases than baseline)
2. define a case (what r u counting) and conduct a case finding (define criteria and find other cases)
3. tabulate and orient data -person place time - to make data usable
4. take immediate control measures if possible
5. formulate and test hypothesis through more analytical studies
6. evaluate and implement additional/ different control measures
7. communicate to professionals and the public
- not always in this order
- not all the steps always happen
66
What is contact tracing important for?
- finding patient 0
- needed to set up future case control studies
- allows you to find RO of pathogen
- requires strong public health department and personal hours
- ex. stds
67
What are the types of outbreaks?
- common / point source
- propagated
68
What is a point source outbreak?
- typically infects a smaller number of people
69
What is a propogated outbreak?
- spread from person to person in population
- repeated burts are continually getting larger
70
Are outbreaks typically point source or propogated?
somewhere between the two depending on RO
71
why are healthcare associated infections concerning?
- increased hospital stay
- increased medical costs
- extra pain in patients
- some can be antibiotic resistant (MRSA, VRE, ESBL)
72
What are the types of infection control measures?
- std or transmission based
73
Are infection control measures for healthcare workers or patients
both
74
What are standard precautions in healthcare?
- PPE
- hand hygiene
- aseptic technique
- respiratory / cough precautions
75
What is aseptic technique?
- safe injection
- safe handeling and disinfection
- sterile equiptment
76
What is sterilization?
- complete removal of all endospores
- needs to be done for anything breaking epithelial barriers
77
What is disinfection?
inanimate objects not breaking epithelal barriers
78
What are antiseptics used for?
people
- like preparing site for needle
79
What is global epidemiology?
- Who
- report diseases of unknown etiology
- needed for identifying emerging infectious diseases
80
What are the difficulties with global epidemiology?
- not all countries have resources
- unwillingness to cooperate
81
What are the steps to diagnosing disease?
1. take history to determine risk
2 clinical exam to find signs
3. establish differential diagnosis
4. tests and define diagnosis
5. review tests and modify treatments
82
What are you looking for when taking a patient history?
- symptoms
- possible exposure (job, travel, sex, drug use
83
What is a differential diagnosis?
- short list of pathogens/ diseases that fit signs and symptoms and history
- inclusive (more things on it than not)
- ranked
84
Are tests and a refined diagnosis always necessary ?
no, if the treatment is the same for everything on the differential diagnosis
85
What is clinical microbiology?
focuses on isolation and characteristics of infectious organisms to manage and treat infections
86
What are the steps to clinical microbiology?
1. get sample
2. transport specimen to lab
3. test spectrum for microbe
4. give results back to doctor to interpret and treat
87
How do you get a sample for clinical microbio?
- use aseptic technique
- biologist would recommend what and when
-nurse would then collects sample
88
What is the most important step of clinical micro?
- transporting the specimen to the lab
- time and how matter
89
What are sensitivity and specificity?
- determines a tests ability to correctly classify a person as a having a disease
- want to minimize false negatives and positives
90
What is sensitivity?
- ability to correctly identify a person with a disease
91
What has lots of true positives and few false negatives?
- sensitivity
92
What is more important sensitivity or specificity?
- sensitivity
93
What is specificity?
- able to identify an individual without a disease
94
What has lots of true negatives and few false positives?
- specificity
95
can you have 100% sensitivity and specificity?
no
96
What is a microorganism culture?
1. enrich number of microbes
2. select for certain bacteria through selective media
3. differentiate among different bacteria through differential media
97
How can you identify micro organisms?
- stains and microscopy
- biochemical tests
- serological tests
- molecular tests
- multiplex PCR
- direct sequencing
98
What are molecular tests?
- could identify pathogen without culture
- used for all pathogen types
- rapid but expensive
99
What is multiplex PCR?
- detects genes in different species for identification
- detects antibiotic resistance
- detects variants of DNA from different strains of same species
100
What does malditof look at?
proteosome instead of genome
101
What does malditof stand for?
mass spectrometry uses laser to create ions to travel to a detector
102
How does malditof work?
- ion mass and ratio gives data to identify AA and proteins
103
What is malditof good for?
- when a pathogens composition is known
- initially expensive but then cheap
104
What does ELISA stand for?
enzyme linked immunoabsorbant assay
105
What does elisa do?
- detects pathogens or antigens in processed specimen
- detects antibody titers in blood
- doesn't always need to be pathogen (pregnancy) test
106
How does ELISA work?
- detects pathogen through enzyme and color change
107
What is DFA?
- direct flourescent antibody
- directs pathogens or antigen in specimin direclty
108
What is supportive care?
- treatments of symptoms ut not pathogens itself
- used when no cure or if treatment doesnt affect outcome
109
What is surgical treatment?
- lancing abscesses (immune system has walled off microbe)
- wound debridement for necrosis
110
What are antimicrobial agents?
- drugs that selectively kill or inhibit growth (static)
- shows selective toxicity towards microbial cells (microbial specific enzymes)
- could be curative or suppressive
111
What do statics do?
- just stop organism growth to help immune system catch up
- drugs that selectively kill or inhibit growth
112
What are examples of passive immunization?
botulism and rabies
113
What are microbial specific enzymes?
shows selective toxicity towards microbial cells
114
What do antibiotics treat?
bacterial infections
- broad and narrow sprctrum
- high chemotoxic index
115
What are antivirals?
- viral infections
- narrow spectrum
- medum to high chemo index
116
What are antifungals?
- fungus infections
- broad to narrow spectrum
- medium to high chemo index
117
What are antiparasitics?
- parasites
- narrow spectrum
- low chemo inde
118
What is the chemo index formula?
TD50/ ED50
119
What therapeutic index does cancer chemo have?
small
120
What is the relationship between TI and Safe range?
directly proportional
121
What is the chemotherapeutic index?
- ratio of toxic does to effective/ therapeutic dose
- describes safe dosing range
- drug should treat pathogen without treating host
122
What chemo index does something have if it has few side effects?
high
123
What are the important factors in drug administration?
- drug concentration must be higher than minimum inhibitory concentration
- depends on how quickly its administered and removed (1/2 life)
- susceptibility of pathogen
- synergistic or antagonistic effects with other drugs
124
What could keep a drug from being effective?
- drug can't reach pathogen (extracellular vs intracellular)
- pathogen is resistant to drug
- intrinsic vs acquired drug resistance
125
What is intrinsic drug resistance?
- all of the microbe has it
126
What is acquired drug resistance?
- not uniform
127
What is combination therapy?
- multiple drugs for different targets
- meant to slow development of drug resistance
128
Why is drug resistance problematic?
- longer infection duration
- drugs have lower chemo index and higher toxicity
- higher cost
- one of the greatest risks to humans (leading COD by 2050)
129
Is drug resistance natural?
- yes
- microbes can produce antimicrobials to compete for space
- genes for resistance are already in a population
- losing battle
130
How can resistance spread?
- spontaneous mutations
- horizontal gene transfer
131
Do antibiotics cause antibiotic resistance?
- no
- just selects for microbes
132
What is MIC?
- lowest concentration of a drug needed to stop pathogen growth
133
How can you test antibiotic effectiveness?
- broth dilutions
- e-test (mic strip` test) *strip embedded with antibiotics at different concentrations
- kirby Bauer disk susceptibility - measures resistance, not mic
134
