Week 4 Part 2 Flashcards
1
Q
What is an antimicrobial?
A
A substance that inhibits or kills microbes (viruses, bacteria, fungi, parasites)
2
Q
How are more antimicrobials administered?
A
by intravenous (IV) or oral routes
3
Q
what are examples of antimicrobial-coated devices?
A
endotracheal tubes or urinary catheters
4
Q
Antimicrobials that activity kill organisms are known as what?
A
bactericial or fungicial
5
Q
antimicrobials that arrest the growth of organisms and assist the host’s immune system in clearing infection are known as what?
A
bacteriostatic or fungistatic
6
Q
What are the major sites of action by antimicrobial classes?
A
-cell wall
-cell membrane
-ribosome
-nucleid acid synthesis
-metabolic pathway
7
Q
What is an antibiogram?
A
a summary of the cumulative susceptibility of bacterial isolates to formulary antibiotics in a given institution or region
8
Q
describe the microtier broth dilution systems (a type of antimicrobial susceptibility test)
A
it uses trays of small-volume wells consisting of various concentrations of antibiotic that are read via an automated, commercial instrument
9
Q
what are three antimicrobial susceptibility tests
A
-microtiter broth dilution systems
-kirby bauer
-E-test of D-test
10
Q
Agar disk diffusion, the antimicrobial susceptibility test, is known as what
A
Kirby-bauer
11
Q
Describe the antimicrobial gradient diffusion method (E-test or D-test)
A
a reagent strip consisting of a gradient of antimicrobial is placed on an agar plate to produce a gradient of concentrations in the medium
12
Q
True or false. Antimicrobial resistance is a natural phenomenon?
A
True
13
Q
what are somethings that have helped antimicrobial resistance develop?
A
-overuse, misuse, and inappropriate use of antibiotics
-the delivery of more complex healthcare that may require longer antibiotic use
-prolonged hospitalisation
-surgical procedures overseas
14
Q
Describe the general mechanisms of antibiotic resistance
A
-intrinsic to bacteria
-acquired by bacteria
15
Q
what are the 4 mechanisms of antibiotic resistance?
A
-drug inactivation/modification
-change in target site of the drug
-change in metabolic pathway
-decrease in drug accumulation
16
Q
What can modification of the target site involve?
A
-binding protein
-ribosomes
-chromosomes
-cell physiology
17
Q
what can modification of the antibiotic involve?
A
enzyme production
18
Q
how the the antibiotic be prevented from reaching the target?
A
-decrease of cell permeability
-active transport out of the cell
19
Q
describe how decrease in drug accumulation is a mechanism of antibiotic resistance
A
-through decreased permeability
-increased efflux
20
Q
what are the 3 mechanisms of horizontal gene transfer?
A
-transformation
-transduction
-conjugation
21
Q
Germ’s may change the antibiotics target so…
A
the drug can no longer fit and do its job
22
Q
Germs get rid of antibiotics using what?
A
pumps
23
Q
germs restrict access by changing what?
A
the entryways or limiting the number of entryways
24
Q
germs develop new cell processes that do what?
A
avoid using the antibiotics target
25
germs change or destroy the antibiotics with what?
enzymes (proteins that break down the drug)
26
what is an example of a bacteria that uses a pump to get rid of antibiotics?
pseudomonas aeurginosa
27
what is an example of a bacteria that breaks down antibiotics?
K. pneumoniae produces carbapenemaes which break down carbapenem drugs and most other beta-lactam drugs
28
describe how/who overused/misused antibiotics
-clinical practice in humans
-agriculture
-veterinary medicine
-contamination of our water systems and food chain
29
when was the first case of penicillin-resistant S. aureus?
1947
30
when was the first case of MRSA?
1961
31
what percentage of S. aureus isolates in Canada are MRSA?
14%
32
MRSA has developed resistance to which class of antibiotics?
B-lactam
33
True or false. MRSA is associated with higher case fatality rates than MSSA?
True
34
VRE are strains of Enterococcus ___ and Enterococcus ___ that have become resistant to high levels of vancomycin
faecium and faecalis
35
Rates of VRE positive blood cultures have ___ in Ontario between January 2009 and July 2015
Doubled
36
True or false. VRE bacteremia mortality burden os greater than that of VSE bacteremia, even following the availability of effective anti-VRE treatments
True
37
What is the name of the enzyme that is produced by some bacteria that inactivates the B-lactam class of antibiotics
Beta-lactamase (B-lactamase)
38
what are examples of antibitoics in the B-lactam class?
peniccilin, cephalosporins
39
ESBL acts on all what?
cephalosporins
40
What are carbapenems?
a class of antibiotics that includes ertapenem, imipenem, and meropenem
41
What is CPE?
an anterobacteriaceae that produces enzyes (carbapenemases) that inactivate carbapenems and a few other classes of antibiotics
42
mortality of CPE is up to __ of severely infected patients
50%
43
what are rates for antimicrobial stewardship expressed as?
per 100 admissions or 1,000 patient days
44
What are some priority antimicrobial-resistant organisms in Canada?
-MRSA
-VRE
-CPE
-C. diff
-Gonorrhea
-TB
-Streptococcus pneumoniae
-streptococcus pyogenes
-Typhoidal and non-typhoidal salmonella enterica
-acinetobacter species
-campylobacter species
-E. coli
45
Between 2014-2018, the proportion of multidrug-resistant gonorrhea infections has___
doubled
46
the rate of HAI VRE BRI _ _ _
more than doubled
47
the rate of community-assocaited MRSA BSI increased by _%
140%
48
Approximately 20% of patients diagnosed with VRE an MRSA BRI died with _ days of diagnosis
30
49
The effectiveness of carbapenems is threatened by a _-fold increase in the number of patients testing positive for CPE without signs of infection
9-fold
50
In Typhoid fever, ceftriaxone resistance increased from nearly undetectable levels to _%
3%
51
the rapid emergence of E. faecium sequence type _ is associated with rising levels of resistance to important antimicrobials
1478
52
HA-CPE cases are often associated with what?
international travel and international healthcare exposure, although domestic nosocomial transmission appears to be increasing
53
True or false. HA C. diff cases have decreased by 15% between 2015-2018
True
54
what are viruses classified according to?
-type of genetic material
-presence or absence of envelope
-shape of the protein capsid
55
what type of genetic material can a virus have?
-DNA or RNA
-Double-stranded vs. single-stranded
-if single-stranded, positive sense vs. negative sense
56
what are the smallest viruses?
parvoviruses (B19) (18-25mm)
57
How do bacteria replicate?
by binary fission
58
What is the surface of a virus?
protein shell/lipid envelope
59
True or false. Viruses are acellular therefore they are neither eukaryotes or prokaryotes?
True
60
Viruses are an _ intracellular parasite
obligate
61
viruses are classified in families and genera based on _
genome type
62
viruses contain _ _ (either RNA or DNA) surrounded by _, and in some cases, other components such as a _-_ _
nucelic acid; protein; membrane-like envelope
63
What are the 3 possible geometric shapes of a virus?
-cosahedral (spherical)
-helical (rod-shaped)
-complex
64
Does a virus have metabolic genes?
No, they use the hosts metabolic resources
65
what is the purpose of the capsid of a virus?
1. protective outer shell surrounding viral nucleic acid
2. protects the nucelic acid from the environment
3. contains capsid spikes (built of capsid protein subunits used for binding to cell surface proteins)
66
Outside the host cell, the virus particle is known as a?
virion
67
what is a virion?
a virion is metabolically inert and does not grow or multiply until it enters a living cell
68
what are the 5 steps of viral replication?
1. attachment
2. penetration
3. replication
4. maturation
5. release
69
describe the attachment step of viral reproduction
the virion attaches to a complementary receptor site on the host cell. Virus attachment is specific (i.e., Epstein-Barr virus attaches to receptors on B lymphocytes)
70
describe the penetration stage of virus replication
the virion enters the host cell through a process called endocytosis, meaning the host cell engulfs the virus
71
describe the replication stage of viral reproduction
viral DNA or RNA directs the host cell to begin synthesis of viral components. Viral replication use host cell ribosomes, energy sources, and amino acids to produce these components.
72
describe the maturation stage of viral reproduction
the viral components essentially assemble into viral particles spontaneously forming daughter virions
73
describe the release stage of viral replication
the host cell lyses or the virus buds through the cell wall and the daughter virions are released.
74
True or false. Some viruses lie dormant in the host cell for months or years and after the latent period, new virions form and cause damage to host cell
True
75
What is a susceptible cell?
-has receptors for the virus (usually glycoproteins)
-capable of supporting viral replication
76
What are the three methods of viral entry?
1. endocytosis
2. direct fusion
3. nucleus acid translocation
77
describe endocytosis
the entire virus is engulfed by the cell and enclosed in a vacuole
78
describe direct fusion
the virus fuses with the cell membrane of the host cell. the enveloped viruses take some of the host membrane with them
79
describe nucleic acid translocation
the capsid adheres to the host cell membrane. There is partial rearrangement of the virion. the nucleic acid passes directly into the host
80
Non-enveloped viruses will often gain viral entry via
nucleic acid translocation
81
What are some examples of DNA viruses
-Herpes
-Chickenpox
-Hep B virus
-Epstein-Barr Virus (mononucleosis)
82
Describe non-enveloped viral assembly and release
assembly in the cytoplasm. release through lysis of host cell
83
what would be the host for virus assembly and release of an enveloped virus?
lipid and carbohydrate
84
During DNA virus replication, DNA becomes integrated with the nucleus. This can lead to what?
latent infection
85
what can trigger a latent infection to start replicating?
-stress, UV lite (cold sores)
-immune suppression
-unknown triggers
86
what is an example of a retrovirus (an RNA virus)
HIV
87
what are examples of RNA viruses?
-SARS
-Influenza
-Common cold
-Hep C
-Ebola
-COVID-19
-West Nike
-Dengue
-Mers
-Polio
-Rabies
-Hep E
88
What are examples of DNA viruses?
-Parvovirus
-Cowpox
-Monkeypox
-Herpes
-Chicken pox
-Epistein-Barr
-Smallpox
-Cytomegalovirus
89
What are the 3 types of antiviral drugs?
1. drugs interfering with viral replication (polymerases, translation)
2. Protease inhibitors (protein processing)
3. Virus release
90
What are the 3 types of Influenza?
A, B, and C
91
Which influenza types are responsible for epidemics?
A and B
92
what is the influenza incubation period?
1-4 days
93
what is the reservoir for influenza?
humans, mammals, and birds
94
Retrovirus replicates via what?
reverse transcriptase
95
True or False. Noroviruses are Enveloped, single-straned RNA viruses
False. Noroviruses are non-eveloped, single-stranded RNA viruses
96
how big are noroviruses?
27-40nm
97
what family does norovirus belong to?
Caliciviridae
98
what is the incubation period for norovirus?
12 to 48 hours
99
When does shedding begin with norovirus?
before onset of symptoms, and may persist for 4 weeks or more
100
how is norovirus transmitted?
oral fecal route
101
how long should droplet contact precautions be maintained for norovirus?
48 hours after symptom resolution
102
Is meales enveloped or nonenveloped? Is measles RNA or DNA?
enveloped; RNA
103
Measles belongs to what genus and what family?
Morbillivirus; paramyxoviridae family
104
what are some measles symptoms?
fever, cough, coryza, conjunctivities, maculopapular rash beginning on the face, koplik spots
105
how is measles transmitted?
Airborne
106
what is the incubation period for measles?
8-12 days
107
Those exposed to measles should be placed on airborne precautions from day _ after first exposure until day _ after last exposure
5; 21
108
chicken pox is also known as what?
human herpesvirus 3
109
Chickenpox is a member of what family, subfamily, and genus?
herpesviridae family; subfamily alphaherpesvirinae; genus varicellovirus
110
what is the chickenpox incubation period?
14-21 days
111
how is chickenpox transmitted?
Airborne
112
how long should chickenpox precautions be maintained?
Until all vesicles have crusted over
113
What disease is herpes zoster?
shingles
114
What is shingles characterized by?
grouped vesicular skin lesions in the distribution of 1 to 3 sensory dermatomes
115
Localized shingles requires _ precautions; disseminated requires _ precautions
no additional precautions; airborne
116
what is the reservoir for Ebola?
Bats
117
True or false. Ebola can only be spread when a patient is symptomatic?
True
118
What is the incubation period for Ebola?
2-21 days
119
How is Ebola spread?
through direct contact with blood or body fluids of an infected person or through contact with objects that have been contaminated with the blood or body fluids of an infected person
120
What is Creutzfeldt-Jakob disease?
Transmissible spongiform encephalopathies (TSEs or prion diseases) constitute a group of rare, rapidly progressive, universally fatal neurodegenrative diseases of humans and animals
121
What body system does CJD affect?
the central nervous system
122
how many cases of CJD are there annually?
1 to 1.5 cases per million people
123
what is the CJD incubation period?
15-120 months
124
the onset of disease for CJD peaks in what age group?
60-74 years
125
what is the diagnostic test for CJD?
usually autopsy
126
Is there treatment for CJD?
No
127
What type of virus is rabies?
single stranded RNA virus
128
what family and genus does rabies belong to?
Rhabdoviridae family; Lyssavirus genus
129
What is the reservoir for rabies?
mammals
130
what is the incubation period for rabies?
3 to 8 weeks
131
What is the diagnostic test for rabies?
direct fluorescent antibody (DFA)
132
What does a direct fluorescent antibody test detect?
the presence of rabies virus antigen in brain tissue
133
What is the treatment for rabies?
There is no specific treatment
134
Describe post exposure prophalaxis for rabies
immune globulin and vaccine on day 0, 3, 7, and 14 and for unimmunized immunocomprimised patients a fifth dose on day 28
135
What are two examples of fungi?
1. Yeasts
2. Moulds
136
Where are fungi found?
Soil and moist areas
137
what is the shape of the nucleus of a fungi and how big is it?
spherical or ovoid; 6 um in diameter
138
diagnosis of fungal infections is based on information from who?
-clinicians
-radiologists
-pathologists
-*microbiologists
139
what is the primary sterol in the cytoplasmic membrane of fungi?
ergosterol
140
What do antifungals do?
either stop the product or incorportion of ergosterol into membrane
141
is the cel wall of fungi made of peptidoglycan?
No
142
what is the major structure of the cell wall of fungi?
Chitin
143
describe the cellular makeup of yeasts
single-celled, single nucleus with a nuclear membrane, contain organelles
144
in culture, describe the colony yeasts form
smooth and creamy
145
how do yeasts reproduce?
Budding or fission
146
What are two common pathogenic yeasts?
1. Candida spp.
2. Cryptococcus neoformans
147
Molds consist of long, branching filaments of cells called?
hyphae
148
a tangled mass of hyphae visible to the naked eye is called a what?
mycelium
149
what are 2 opportunistic pathogenic molds?
-Aspergillus spp (invasive pulmonary aspergillosis)
-Rhizopus and Mucor mucromycosis
150
how do molds reproduce?
-Some reproduce asexually by fragmentation of their hyphae
-molds may reproduce sexually and asexually by the formation of spores as a result from fusion of nuclei from two opposite mating
151
describe fungi dimorphism?
can grow as either a yeast or a mould
152
Moldlike forms of dimorphic fungi produce what?
vegetative and aerial hyphae 25 degrees C
153
yeastlike dimorphic fungi forms reproduce by what?
budding at 37 degrees C
154
What are 3 common pathogenic dimorphic fungi?
1. histoplasma capsulatum
2. Blastomyces dermatitidis (chronic skin infections)
3. Coccidiodes immities(respiratory)
155
True or false. Some fungi can be identified directly from a clinical specimen (i.e., skin scraping)
True. These specimens would be incubated at room temperature for several weeks first
156
What are some clinical presentations of fungi?
-respiratory (localized pneumonia, fungus ball)
-cutaneous (scaling, itching, thickening, crusting)
-CNS (headaches, meningitis, brain abscess)
-ocular (keratitis on cornea or inside the eye)
-sinusitis
-urinary tract (kidney infection)
-endocarditis
157
what is systemic mycoses caused by?
dimorphic fungi
158
what is the route of exposure for systemic mycoses?
aerosol/inhalation
159
what does systemic mycoses cause?
respiratory diseases that may spread to blood and other tissues.
160
what are the 3 systemic mycoses and where are they found?
histoplasma: great lakes region
coccidiodes: Arizona
Blastomyces: beaver dams, campers
161
dermatophytes can only infect what?
hair nails and skin
162
what is the name of the dermatophytes family?
Tinea
163
what is Tinea capitis?
ringworm of the scalp
164
What are the target sites of antifungal therapy? (hint: there are 3)
1. cell wall
2. cell membrane
3. mitosis
165
are parasites eukaryotic or prokaryotic?
eurkaryotic
166
how many parasite species affect humans?
About 90
167
what are 3 common parasite groups?
-ectoparasite
-endoparasite
-helminths
168
what are 3 ectoparasites?
-scabies
-bed bugs
-lice
169
is an endoparesite?
a protozoa (in blood or intestines)
170
what are 3 types of helminths?
-nematode
-cestode
-trematode
171
scabies is caused by what mite and what subspecies?
sarciotes scabiei; subspecies hominis
172
how long does it take scabies larvae to emerge?
2 to 4 days
173
describe scabies
the adult feamle burrows into skin and lays eggs. larvae emerge from eggs in 2 to 4 days and develop to nymphs then adults which mate and produce new eggs
174
what is the treatment for scabies?
Lindane cream applied from chin to fingertips for 8-12 hours (head for shorter time). repeat
175
what is the treatment for scabies in pregnant women or infants?
Permethrine 5% (same dwell time but one application is enough)
176
what is the scientific name for bed bugs?
Cimex lectularius
177
How long can bed bugs live without a blood meal?
several months
178
what are the 3 types of lice?
1. pedculus humanus (head)
2. pthirus pubic (pubic or crab lice)
3. pediculus humanus corporis (body)
179
Enterobus vermicularis is more commonly known as what?
pinworm or roundworm
180
where are prevalence rates of pinworm common?
-preschool/school-aged children
-caregivers of infected children
-institutionalized people
181
what is the characteristic of pinworm?
anal itching
182
how is pinworm autotransmitted?
from scratching and ingesting eggs
183
what is pinworms mode of transmission?
oral fecal
184
what is the diagnostic method for pin worm?
cellulose tape (clear adhesive cellophane tape)
185
What is the incubation period for pinworm?
from ingestion of an egg until an adult female migrates to the perianal region is 1 to 2 months or longer
186
Which micoorganism is endemic in the tropics and subtropics?
strongyloides stercoralis
187
Humans may remain infected for decades due to self infection with what microorganism?
strongyloides stercorali
188
what microorganism has the reservoir humans, dogs, and cats?
strongyloides stercoralis
189
Infection with what parasite is often asymptomatic?
tapeworm
190
what is the scientific name for tapeworm?
taeniasis
191
How is tapeworm diagnosed?
by demonstration of the proglottids or ova in feces or the perianal region
192
prevalence of tapeworm is high in what areas?
those with poor sanitation
193
What are tapeworm symptoms?
mild GI symptoms such as nausea or diarrhea
194
what 3 meat products contain different types of tapeworm?
-beef
-pork
-fish
195
What genus does malaria belong to?
Plasmodium
196
what is the malaria incubation period?
7-30 days after bite
197
how is malaria primarily acquired?
from the bite of the female Anopheles genus of mosquito
