Midterm #1 Material Flashcards
(212 cards)
1
Q
Define Microbiology
A
Study of microscopic agents
- 95% of microbes do NOT cause disease
2
Q
What are the two kinds of acellular microbial agents? (non-cellular, lack cell features)
A
- Prions
2. Viruses
3
Q
What is a prion?
A
Infectious proteins with no genetic material
4
Q
What is a virus?
A
Obligate intracellular parasite (cannot replicate without a host) with either RNA or DNA as genome
5
Q
What are the two main categories of cellular microbial agents?
A
- Prokaryotes
2. Eukaryotes
6
Q
What is a defining feature of prokaryotes? What is an example?
A
They lack membrane-bound organelles.
Ex - bacteria
7
Q
What is the defining characteristic of eukaryotes?
A
“True” cells - have typical cellular features such as nucleus, and organelles
8
Q
What are the two different kinds of prokaryotes?
A
- Gram positive (stain purple) - MRSA, E-coli
2. Gram negative (stain pink)
9
Q
What are the three different kinds of eukaryotes?
A
- Fungi
- Protozoa
- Other parasites (multi-cellular and typically larger
10
Q
Are fungi single-celled or multi-celled?
A
Both!
Yeasts are single-celled
Molds are multi-celled
11
Q
What is the defining characteristic of protozoa?
A
Unicellular
single celled organism
12
Q
What happens when we are exposed to PrPsc?
A
PrPsc = abnormal forms (infectious) prions
- they change our normal prions to abnormal prions
13
Q
What do abnormal prions due to the brain tissue?
A
Causes plagues or holes to form in the brain tissue
14
Q
What is TSE?
A
Transmissible Spongiform Encephalopathy
- prion disease
- fatal, incurable
15
Q
What is an example of a prion disease in sheep and in cows?
A
Sheep = Scrapie Cattle = Bovine Spongiform Encephalopathy (BSE) "Mad Cow Disease"
16
Q
What are the different kinds of prion diseases in humans?
A
- Creutzfeldt-Jakob Disease (CJD - 2 kinds; classic and variant)
- Kuru Disease
- Fatal Familial Insomnia
17
Q
What is the difference between classic and variant CJD?
A
Classic = genetic predisposition to it Variant = from eating cattle that are infected
18
Q
What is the median duration of illness?
A
Time the patient will remain alive after diagnosis
19
Q
What is the median age at death, median duration of illness and clinical signs and symptoms of Classic CJD?
A
Median age at death = 68
Median duration = 4-5 month
S and S = dementia, early neurologic signs
20
Q
What is the median age at death, median duration of illness and clinical signs and symptoms of Variant CJD?
A
Median age at death = 28
Median duration = 13-14 months
S and S = Psychiatric/behavioural symptoms, painful sense of touch, delayed neurological signs
21
Q
What does obligate intracellular parasite mean?
A
Must be inside a suitable living host cell in order to propagate - highly specific virus-host cell relationship
22
Q
What does MERS-cov stand for?
A
Middle East Respiratory Syndrome Coronavirus
23
Q
When was the first identified case of MERS-cov?
A
April 2012 in Saudi Arabia
24
Q
What are signs and symptoms of MERS-cov?
A
- fever, cough, SOB, breathing difficulties
- pneumonia
- gastrointestinal symptoms (diarrhea)
25
What does SARS stand for?
Sever Acute Respiratory Syndrome
26
What is the mode of transmission of MERS-cov and SARS?
Droplet (coughing/sneezing)
27
What is an incubation period?
Time between exposure to disease and when you show symptoms
28
What is Period of Communicability?
Time during which an infectious agent can be transmitted directly or indirectly from an infected person to another person
29
What is the incubation period of SARS? MERS?
```
SARS = 2-10 days
MERS = 2-14 days
```
30
What is the period of communicability of SARS? MERS?
SARS =
31
Which has a higher fatality rate, MERS or SARS?
MERS (36%) compared to SARS (10.8)
32
Why will the estimated number of infected people always be a little low?
Because there will always be some infected people that don't go the hospital b/c the symptoms weren't that bad (to warrant hospitalization)
33
How is Ebola spread?
By direct contact with body fluids (blood) of a SYMPTOMATIC infected person (or one who has died from the disease)
34
What is the incubation period (IP) of Ebola?
8-10 days
35
What is the fatality rate of Ebola?
25-90%
36
What are some signs and symptoms for Ebola?
Fever, severe headache, fatigue, muscle pain, followed by diarrhea, vomiting, abdominal pain and unexplained hemorrhage
37
How can an individual help to minimize the spread of Ebola?
- wash hands (soap and water)
| - do NOT touch an infected person OR their body fluids
38
What are the 4 ways that Zika virus can be spread?
1. Mosquito bites
2. Sexual contact
3. Congential transmission (infected mother to fetus)
4. Blood transfusion and laboratory exposure
39
What happens to the body when it is infected with the Zika virus?
Virus attacks the brain cells, there is then not enough pressure on the developing skull - results in skull collapse (microcephaly)
40
What two types of mosquitoes spread the Zika virus? Why is it not a concern in Canada?
1. Aedes aegypti
2. Aedes albopictus
Those species don't live in Canada
41
When do the species of mosquitoes that carry Zika virus feed? West nile virus?
Zika = Daytime
| West Nile = Dusk to Dawn
42
What is the name of the mosquitoes species that carries the West Nile virus?
Culex
| - we have these in Canada!
43
What are some signs and symptoms of Zika virus?
Fever, rash, joint pain, conjunctivitis, muscle pain and maybe headache
44
What are the current challenges of the Zika virus (3)?
- incubation period is unknown
- when and how it is passed from mother to fetus is unknown
- no FDA approved commercially diagnostic test
45
What are the two most common causes of healthcare associated infections?
1. Gram-positive (C. diff, MRSA, VRE)
| 2. Gram-negative (E.coli)
46
What are the two types of fungi (eukaryotes)?
1. Yeasts (unicellular)
| 2. Molds (multicellular)
47
What is toxoplama?
Single-celled eukaryotes
- spread by contact with cats/cat litter
- consumption of raw/undercooked meat from infected animals
- ingestion of contaminated water
- infected mother to fetus
48
What group/class do parasitic worms fall into?
Eukaryotes, multicellular
49
What are three different kinds of parasitic worms?
1. Taeniasis (tapeworm)
2. Anisakiasis (from eating raw fish)
3. Snail/Brazilian fever - contact with contaminated water
50
What is the mode of transmission?
How the disease is transmitted
51
What is the portal of entry?
How the disease infects the new host
52
What is the portal of exit?
How the disease leaves the infected individual
53
What is epidemiology?
Study of the distribution of a disease
(or an event [what], and their determinants [how], in a given population [who] and location [where] during a defined period [when])
54
What is Dr. John Snow (Father of Epidemiology) credited with?
Discovered the source of cholera outbreak in London in 1854 was WATER
55
What is GIS and how does it help with epidemiology?
Geographic Information System
| - used to help investigate outbreak and prepare for outbreak management
56
Define communicable or infectious diseases
Illnesses caused by an infectious agent and/or its toxin that can be transmitted directly and/or indirectly from human-human or animal-human
57
What is the only disease that we were able to eradicate worldwide through vaccination?
Smallpox!
58
What is the name for diseases that are transferable from animals to humans?
Zoonotic diseases
| - rabies, avian flu, lyme disease, west nile virus
59
What are the three possible outcomes after getting exposed to a disease?
1. No illness
2. Colonization
3. Carrier state
4. Illness (with mild to severe s and s)
60
What does it mean if you are colonized with a disease?
Presence and multiplication of microbes in a host without tissue invasion/damage
- symptomatic transmission
61
What does it mean if you are in a carrier state?
You have the disease (but do not show signs and symptoms) and can transmit the disease AT ANY TIME
- asymptomatic transmission
62
What is the incubation period?
Time between exposure to an infectious agent and the appearance of first signs and symptoms
63
What is the prodromal period?
Early stage of signs and symptoms
64
What is the period of invasion?
Worsening of signs and symptoms, reaching the height of infection (possibly death)
65
What is the convalescent period?
Signs and symptoms diminish and disappear eventually (recovery)
66
What are the 4 clinical stages of infectious disease?
1. Incubation period
2. Prodromal period
3. Period of invasion
4. Convalescent period
67
When is a person contagious?
During the period of communicability
68
Define communicability
The number of people an infected person can infect in a large susceptible population [Ro]
69
What does it mean if Ro is > 1? And
The greater the Ro, the more contagious the disease
| -
70
What is the basic reproductive number?
The Ro
71
Why is the Ro number important?
- helps predict how fast and far a disease can spread
- help to estimate morbidity and mortality
- helps with resource allocation
72
What is the incidence of disease?
Number of NEW cases in a given time period
73
What is the prevalence of a disease?
All cases in a given time period (OLD + NEW cases)
74
What is the tip of the iceberg effect?
Many people could be infected but don't show any signs or symptoms
75
When comparing the incidence and prevalence of HIV, why are the numbers different?
Prevalence is a higher number b/c people living with HIV are living LONGER (effective drug treatments)
76
What is disease surveillance?
Systematic approach to collect, analyze, interpret and disseminate disease data to all stakeholders in a timely fashion
77
What are the two categories for reportable diseases?
1. Schedule A: reportable by ALL SOURCES (dr, RN, labs, public)
2. Schedule B: reportable by LAB ONLY
78
What is prevalence data NOT useful for?
Detecting outbreaks and identifying determinants of disease
79
Define sporadic occurance
Randomly occurring cases of disease - not related epidemiologically
80
Define endemic
Cases of disease persistent in a given location in a relatively stable fashion (Lyme disease)
81
Define epidemic
Incidence exceeds the historical number (mean) of cases (ex. seasonal flu epidemic)
82
Define pandemic
World-wide or global epidemic (H1N1)
83
What are healthcare-associated infections (HAIs)?
Infects that occurs during or after hospitalization or stay in a health-care insitutution
- 48 hours after hospital admission
- up to 3 days after discharge
- up to 30 after an operation
84
What is CA-MRSA?
| What is HA-MRSA?
```
CA = community acquired
HA = Heathcare acquired
```
85
What age group does CA-MRSA affect? HA-MRSA?
```
CA = teenagers and younger adults
HA = older age groups (50+, 80+)
```
86
What are some common types of HAIs?
- UTI (catheter-associated) (30-40%)
- Lower respiratory tract infections (10-20%)
- Surgical site infections (15-25%)
- Blood (central line-associated blood stream infections) (5-15%)
87
What is cystitis?
| What drug is used?
A bladder infection
| - Nitrofurantoin (resistance is uncommon)
88
What is pyeleonephritis?
| What drug is used?
Kidney infection
| - IV ceftriaxone
89
What are carbapenems?
ESBLs
| (extended spectrum beta lactamases
90
What is an SSI?
Surgical site infection
91
What are the classifications of SSIs?
1. Incisional
- Superficial
- Deep
2. Organ/space
92
What does a superficial surgical site infection involve?
Involves only skin and subcutaneous tissue
93
What does a deep surgical site infection involve?
Involves deep soft tissues (fascia and muscle)
94
What does an organ/space surgical site infection involve?
Involves any part of anatomy other than incision opened or manipulated
95
What is septicemia?
Bloodstream infections
96
What is primary septicemia?
Direct introduction of microbes into blood (from patient themselves, HCWs, or through central lines)
97
What is secondary septicemia?
The spread of microbes from a pre-existing distant infection
98
What are the clinical signs and symptoms of SSIs (surgical site infections)?
- Febrile
- Redness (Erythema)
- Swelling
- Warm
- Tender/pain
- Drainage?
99
Approximately how many patients will acquire an HAI?
5-10%
= > 200,000 cases per year
= > 8,000 deaths per year
100
What are the direct costs of HAIs?
Associated with providing care to patients (estimated to be $1 billion
101
What are the indirect costs of HAIs?
- Loss of productivity (someone calls in sick)
- Loss of business income
- Lawsuits (medical malpractice)
102
Which disease had the biggest economic impact of HAIs?
SARS
| - $30-50 billion USD
103
What is an agent?
The cause of an infectious disease (microbial toxins, bacteria, viruses, fungi, protozoa, parasites, prions)
104
What is a host?
A living organism that harbours an infectious agent
105
What is the definition of environment (pertaining to the epidemiological triangle)?
Settings external to the host that allows for transmission of the agent
106
Why can an agent survive in a host?
Because the host allows for the sustained survival of the infectious agent that resides in/on its body UNDER NATURAL CONDITIONS (not produced in a lab)
107
True or false:
| The infectious agent may or may not produce a disease in the host but is provided opportunities for transmission
TRUE
108
What are the three types of relationships that humans can have with microbes?
1. Mutualistic
2. Commensal
3. Parasitic
109
What is a mutualistic relationship?
Benefits both parties
110
What is a commensal relationship?
No harm but not benefit either
111
What is a parasitic relationship?
Infectious agent benefits; host is harmed
112
What are normal microbiota?
Agents that permanently live in the human body
113
What are transient microbiota?
Agents that may inhabit and reproduce in a host briefy, but the hosts natural defenses do not allow them to become permanent
114
What are some of the benefits of normal microbiota?
- aid in development and maturation of host immune system
| - protect host from pathogens (via competition or production of antimicrobial substances)
115
What is the potential harm of normal microbiota?
If the host becomes immunocompromised, they could become opportunistic pathogens
116
What is an opportunistic pathogen?
Pathogens that take advantage of a weaker host (in normal conditions they would not cause problems)
117
What is an obligate pathogen?
Agents that always cause disease/damage in the host in order to be transmitted
118
What is a primary immunodeficiency?
Person is born with a genetic defect in the immune system (genetic susceptibility)
119
What is a secondary immunodeficiency?
An acquired susceptibility (AIDS & TB)
120
What are 3 examples of medical conditions that cause secondary immunodeficiencies?
Cancer, cystic fibrosis, co-morbidities (diabetes and obesity)
121
What are 3 examples of medical therapies that cause secondary immunodeficiencies?
1. Anti-inflammatory agents
2. Anti-rejection drugs (transplant patients)
3. Oncology interventions (radiation and chemotherapy)
122
What are some examples of factors that affect the host's immune system (making them more susceptible to acquired immunodeficiencies)? Why?
1. Chronic stress
2. Lifestyle habits (alcohol, smoking, drugs)
3. Age
4. Sex (differences in anatomy, hormones, pregnancy, etc)
123
Why do chronic stress, lifestyle habits, age, sex, and malnutirion affect the host's susceptibility to acquired immunodeficiencies?
Impairs the amount and/or functions of cells and chemical messengers associated with inflammatory and immune responses
124
Why is breastfeeding good for a child? What happens to the antibodies that the mother give to the child?
Mother shares antibodies in utero with the fetus.
Neonates receive some protection from breastfeeding
- but it doesn't last forever (they are MOM's antibodies, not the CHILD's, so the child will actually attack them - they are foreign bodies)
125
Why does the mother not reject her baby as a foreign thing?
Mother's are immunosuppressed (to a degree)
126
What are MORE factors that influence a host's risk of infection?
- socioeconomic status
- occupational exposure
- travel history
- person hygiene
- vaccination
- exercise/physical activity
- risk activities (needle sharing)
127
What are MORE factors that influence a host's risk of a HAIs?
- invasive dwelling devices
- lengthy instrumentation and/or surgery
- long stay in healthcare facility
- prior and prolonged use of antimicrobials
- presence of existing wounds
128
What are 6 different kinds of agents?
1. Bacteria
2. Viruses
3. Protozoa
4. Fungi
5. Parasite and prions
6. Microbial toxins
129
Define communicability
Ease of transmission of the agent
130
What are 3 agent factors that influence the risk of infection?
1. Communicability
2. Survivability
3. Adaptability
131
What is the formula for communicability?
Ro = C * P * D
```
C = number of contacts
P = probability of transmission per contact
D = Duration of infectiousness (POC)
```
132
Define the infectious dose (ID)
Minimum number/dose of agents required to cause an infection
| - infection will occur if exposure exceeds infective dose
133
Define survivability
How well an agent survives on a surface
134
What happens if a person comes into contact with a disease that is over the clinical infection threshold?
Person will acquire the disease
135
What happens if a person comes into contact with a disease that is over the subclinical infection threshold?
Exposure level still exceeds infective dose; person will have mild or no s/s
136
Which agents have the highest survivability? The lowest?
```
Highest/best = prions
Lowest/worst = viruses with lipid envelopes
```
137
What is the virulence factor?
Intrinsic characteristics of an agent that enable them to cause tissue damage/disease
138
What are 2 pieces of the virulence factor?
1. Ability to evade and/or subvert the host's defenses
| 2. Survival in the host (longer period of communicability = greater chance of transmission)
139
How does an agent adapt to or in the host's environment?
1. Mutation
| 2. Genetic exchange
140
Define direct transmission
Transmission from infected host to another
141
Define indirect transmission with intermediate hosts and adaptation
Agent may adapt and become more efficient
| - adapt to different host species
142
What is reassortment?
A mutant strain of the agent
- avian flu and the human flu strains mix with a mutation
- we ALL lack immunity!
- if it has aspects of the human flu strain, it will be more successful at human-human transmission
143
What are factors that affect the virulence of an agent?
1. Adherence/attachment
2. Toxigenicity
3. Invasiveness
4. Evasion/subversion of host defenses
5. Immunopathology
144
Define toxigenicity
Ability to produce toxins
| - endotoxins or enterotoxins
145
Define immunopathology
Sometimes the immune response is too strong and causes damage to the host from itself
146
What is a micro-environment?
Where the agent is located
147
What is the macro-environment?
Where the host is located
148
What are 5 micro-environmental factors that influence how well an agent survives, grows and transmits?
1. Oxygen
2. Water
3. Temperature
4. pH
5. Nutrients
149
What is an obligate aerobe?
Needs oxygen
- will die without it
- neutralizes toxic forms of oxygen
150
What is an example of an obligate aerobe?
Mycobacterium
151
What is a facultative anaerobe?
Increased growth in the presence of oxygen
| - both aerobic and anaerobic
152
What is an example of a facultative anaerobe?
- Streptococcus
- Staphylococcus
- Enterobacericeae
- MRSA
- VRE
153
What is an obligate anaerobe?
Can only survive is oxygen is absent
| - will die in the presence of O2
154
What is an example of an obligate anaerobe?
Clostridum
155
What is an aerotolerant anerobe?
Does not care if oxygen is present or not
| - does NOT use O2
156
What is an example of an aerotolerant anaerobe?
Lactobacillus
157
What is a microaerophil?
Requires low concentrations of oxygen for growth
158
What is an example of a microaerophile?
Neisseria gonorrhoeae
159
What are capnophiles?
Agents that prefer high concentrations of CO2
160
What temperatures do psychrophiles prefer?
Cooler temperatures - freezing will not kill them, only slow their growth
161
What temperatures do thermophiles prefer?
Extremely high temperatures
162
What temperatures do mesophiles prefer?
30-40 degrees C
| = HUMAN BODY temperatures!
163
If a container of food in the fridge contained Clostridium Botulinum, where in the container would they be found?
AT THE BOTTOM
- obligate anerobic
(further away from oxygen source)
164
True or False:
| The optimum pH range for an agent is high
False:
| The optimum pH range for an agent is quite narrow
165
What pH range are infectious agents typically? What are they called?
pH 5.5-8
| Neutrophiles
166
What is the name for agents that prefer acidic environments?
Acidophiles
167
What is the name for agents that prefer basic environments?
Alkalophiles
168
Do fungi or bacteria prefer a more acidic environment?
Fungi prefer a more acidic environment
169
What does a low Aw value mean?
The agent can survive WITHOUT a lot of water
170
What is the water activity level (Aw)?
Amount of water available in a micro-environment (such as food)
171
What can you add to food to lower the Aw value?
Salt or sugar
| Dry it!
172
What happens to bacteria in a hypertonic environment?
Water will leak out of the bacteria and into the solution (to try to dilute it)
- plasmolysis
173
What are the 6 essential nutrients?
```
Carbon
Nitrogen
Hydrogen
Sulfur
Phosphate
Minerals
```
174
Define heterotroph
Organism that needs to eat or absorb their energy source
175
Define chemoheterotroph
Organism that uses the metabolic conversion of the nutrients from other organisms for energy
176
Define autotroph
Organism that makes it's own food
- Photoautotroph
- Chemoautotroph
177
What are some macro-environmental factors that influence infectious disease transmission?
- poor sanitation
- overcrowding
- construction activities
- contaminated air
178
How can staffing affect infectious disease transmission?
- inadequate staffing
- inexperienced staff
- indifferent attitude
- knowledge deficit
- failure to identify cases
179
What are the 6 steps in the chain of transmission?
1. Infectious agent
2. Reservoir
3. Portal of exit
4. Mode of transmission
5. Portal of entry
6. Susceptible host
180
What is a microbial reservoir?
A living or non-living object that permits sustained survival and transmission of an infectious agent
181
How is a secondary reservoir different from a primary reservoir?
Secondary doesn't support replication
182
What are the three types of carriers?
1. Incubatory
2. Convalescent
3. Healthy
183
What does it mean if the source of infection is endogenous?
Patient themselves (self-infection) is the source of infection
184
What does it mean if the source of infection is exogenous?
Living reservoirs: (OTHER patients), health care workers or Non-living reservoirs: air, water, food, catheter, IV fluids, ventilators
185
What are the two main modes of transmission?
1. Direct (transmitted by direct contact between reservoir and host)
2. Indirect (transmitted to host via intervening agent)
186
What are the 5 categories of modes of transmission?
1. Air-borne
2. Droplet spread
3. Direct contact
4. Indirect contact
5. Common vehicle
187
What is vertical transmission?
Transmission from mom to baby
- trans-placental
- intrauterine transmission
- infected birth canal
188
What is horizontal transmission?
Transmission from person to person
189
What are examples of viral diseases that are transmitted through direct implantation or biting?
```
Rabies
Bloodborne virses (hepatitis B and B, HIV)
```
190
What are example of bacterial diseases that are transmitted through direct implantation or biting?
```
Tetanus (Clostridium tetani)
Capnocytophaga canimorsus (found in dog's mouths)
```
191
What are examples of diseases that are spread through direct droplet transmission?
- SARS
- Influenza
- Measles
- Mumps
- Rubella
- Common cold
- Meningitis
192
How is airborne transmission different than droplet transmission?
Airborne = smaller droplets (1-5 micro meters in diameter)
- can stay suspended in air indefinitely
- agents remain viable and infectious for an extensive period of time
193
What is an example of a disease that is an airborne transmissions?
- TB (mycobacterium tuberculosis)
| - Legionnaire's disease
194
What is a vector?
Living organisms that transmit an infectious agent to a host
195
Vectors are normally, what kind of living thing?
Arthropods (mosquitoes, ticks)
196
What are the two kinds of vectors?
1. Biological
| 2. Mechanical
197
What is a biological vector?
An organism which not only transports a pathogen, but also plays a role in the life cycle of the pathogen
198
What is a mechanical vector?
An organism which ONLY transports a pathogen
199
True or False:
| Biological vectors are reservoirs and hence can be considered a mode of direct transmission
TRUE!
| - because they can survive, live, and multiply in a BIOLOGICAL vector
200
True or False:
| Non-living objects do not act as an intermediary for indirect transmission
FALSE!
| Non-living object DO act as an intermediary for indirect transmission
201
What is a common vehicle?
Infects multiple hosts (ex. food and water during an outbreak)
202
What is a fomite?
Non-living objects that can act as intermediaries for indirect transmission
203
What does the route of transmission often refer to?
Portal of entry (ingestion route) but sometimes can include both portals of entry AND EXIT (fecal-oral route)
204
What are the portals of exit and entry?
Body parts/substances through which infectious agents leave and enter the body respectively
205
What are some common portals of entry?
- mucous membrane
- conjunctiva
- respiratory tract
- gastrointestinal tract
- genitourinary tract
- skin
206
What is the parenteral route?
Through punctures, injections, bites, cuts, wounds, and surgical incisions
207
What does IPCT stand for?
Infection Prevention and Control Team
208
What are the roles and responsibilities of IPCT?
To develop, implement, and monitor the effectiveness of IPC policies and procedures by:
- establishing guidelines
- providing advice
- auditing
209
What is the main objective in contact tracing?
To identify those who have come into direct contact with person(s) who have a highly contagious and/or dead infectious disease
- to prevent further spread of the infection
- to provide required interventions
210
What is mupirocin (Bactroban)
Antibiotic used for intranasal decolonization
211
What is cholorhexidine gluconate?
Antiseptic for bathing patients
212
What is photo-disinfection?
Use non-thermal light energy to decolonize nasal carriage
