Microbiology Refresher - Viruses and Fungi Flashcards
(96 cards)
1
Q
What are the single most important cause of infectious disease morbidity and mortality worldwide?
A
viruses
2
Q
What is going to expose us to new and emerging pathogens/viruses?
A
continued destruction of natural habitats and interactions with wildlife
3
Q
What describes what happened around 1908, where an event occurred which was possibly the first contact between humans and HIV virus?
A
The “cut hunter” hypothesis
4
Q
What is the hypothesis that describes a chimp and human hunter had a bloody encounter and the human acquired SIV (simian immunodeficiency virus) which later mutated to HIV?
A
the “cut hunter” hypothesis
5
Q
Most research of viruses in humans is centered on viruses of what?
A
the respiratory tract
6
Q
Constant exposure to a variety of viruses does what?
A
primes our immune system (may be beneficial or detrimental)
7
Q
What has been linked to systemic inflammatory diseases?
A
viruses
8
Q
What causes inflammation and multi-organ disease?
A
HIV
9
Q
What is linked to MS?
A
epstein-barr virus
10
Q
Viral infections prime the T-helper cell 1 system which acts as what?
A
protective immunity (more exposure=more immunity)
11
Q
What is linked to allergic diseases including asthma?
A
Th2
12
Q
Viruses alter the respiratory epithelium and promote (1)?
A
- secondary bacterial infections (influenza and epstein-barr)
13
Q
What are some common pathogenic viruses in humans?
A
- respiratory viruses
- gastrointestinal tract viruses
- skin viruses
- other viruses (Zika)
14
Q
Viruses may have what that is not encoded by the genome of the virus?
A
a lipid envelope
15
Q
What can viruses do to the lipid envelope from the host as it buds off the host cell?
A
they can steal the lipid envelope
16
Q
What uses its own DNA or RNA to encode the protein spikes on the lipid envelope?
A
viruses
17
Q
What can changes in spike proteins on viruses lead to?
A
resistance in treatment
18
Q
What are the different types of viral capsids?
A
- enveloped
- helical
- polyhedral
- icosahedral
19
Q
What types of viruses dry out easier and are usually transmitted by respiratory, parenteral (blood), and sexual routes?
A
viruses with lipid envelopes
20
Q
What types of viruses are more stable and usually transmitted in the fecal-oral route?
A
viruses without lipid envelopes
21
Q
How are viruses classified?
A
- type and structure of viral nucleic acid used for replication (DNA vs. RNA)
- symmetry of viral capsid
- presence or absence of a lipid envelope of the virus
22
Q
Where are the different locations of viral replication?
A
- DNA viruses - in nucleus
- RNA - in cytoplasm of host
23
Q
What uses reverse transcriptase to reverse transcribe the RNA in their own genome into DNA, which is then incorporated into host cells?
A
retroviruses (HIV)
24
Q
What are the steps that occur when the virus meets the host?
A
- attaches to host cells
- receptors on virus attach itself to specific viral receptors of the host cell
- virus enters host cell by fusion or endocytosis
- viral capsule disassembles
25
Once the virus has entered the host cell, it uses some of its own proteins and host ribosomes to (1), creating many (2)
1. reproduce
2. viral progeny
26
Release of viral progeny occurs by what ways?
1. budding from cell membrane
2. secretion
3. cell lysis
27
What can induce apoptosis in host cells?
RNA and DNA viruses
28
What results in damage to host cell structure and sometimes death of infected host cells?
apoptosis
29
What is the mechanism of infection for influenza?
- upon meeting respiratory epithelium, hemagglutinin on envelope of virus attaches to sialic acid receptor on epithelial cell surface
- viral structure is internalized into cell in an endosome
- further changes allow genetic material of virus to uncoat, leave the virus, and enter the cytoplasm, making its way to the nucleus
- within nucleus, viral RNA replication occurs, formed viral progeny and releasing to cell surface
- neuraminidase allows virus to "escape" cell and "not stick" to surface of host cell
30
What allows influenza virus to escape cell and not stick to surface of host cell?
neuraminidase
31
What are direct methods of virus transmission?
- person-to-person
- droplet
32
What are indirect methods of virus transmission?
- fecal-oral
- airborne
- fomite (surface)
33
What are vector methods of virus transmission?
- insect bite
34
What type of viruses produce characteristic upper respiratory symptoms?
common cold viruses
35
What type of virus has a recognizable rash?
chicken pox (varicella virus)
36
What type of virus causes anosmia (inability to smell) and characteristic changes on lung imaging?
COVID-19 (delta variant)
37
What may help in diagnosing viruses?
non-specific testing such as CBC panels
38
What is often normal in viral infections?
WBC
39
What are some different specific tests that exist for viruses?
- COVID test
- Influenza test
- mono (EBV) testing
40
What can be used to diagnose viral infections, but is not performed routinely because it is very expensive?
respiratory pathogen panel
41
Respiratory pathogen panels are most often used in what type of setting?
hospital settings for patients who are critically ill
42
Respiratory pathogen panels can show what types of organisms?
- viruses
- atypical bacteria
43
What do antiviral treatment mechanisms interfere with?
- binding to host cell
- penetration of virus into cell
- action of viral polymerases involved in replication of virus
- release of virus from infected cell
44
Influenza antivirals bind to (1) so progeny cannot be released?
1. neuraminidase
45
What does this describe:
- each antibody is produced by a specific B cell line
- targets a specific antigen on the cell surface
monoclonal antibodies
46
What are monoclonal antibodies used to treat?
- cancer
- various autoimmune diseases (MS, rheumatoid arthritis)
47
generally, most antivirals are targeted toward?
1 virus
48
In severe cases (where catastrophic consequences can result), patients can be started on what until diagnosis is known?
antivirals and antibiotics
49
Depending on the symptoms, the standard of care may be to not identify the viral pathogen at all. This could be the cases in which illnesses?
- common cold
- acute sinusitis
- acute bronchitis
- most pneumonia treated outpatient basis
50
Viral pneumonia may be (1) while bacterial pneumonia may be (2)
1. bilateral
2. unilateral
51
Even if you have viral pneumonia, what is usually given?
antibiotics because a secondary bacterial infection usually occurs
52
What can be divided into yeasts and molds?
fungal infections
53
Yeasts are (1) organisms while molds are (2) organisms
1. unicellular
2. multicellular
54
How do yeasts reproduce?
asexually by budding
55
What can be identified through microscopic identification of budding (ovals) or present of hyphae?
yeasts
56
What is a common example of a yeast that causes disease?
Candida albicans
57
What appears as filamentous structures and appear "fuzzy" or "fluffy" or "velvety" when grown on agar?
molds
58
What is a common mold that can cause disease?
Aspergillus fumigatus
59
What is a predominant yeast found on and in the human body and can cause infection of the oral cavity, GI tract, and vagina?
Candida
60
Patients with immunosuppression or on recent antibiotics have increased risk for (1) infection
1. candida
61
What does it mean if Candida is found on blood culture?
likely pathogenic
62
Constant environmental exposure to fungi can lead to?
fungal infections
63
What are ways we are exposed to fungal infections?
- walking barefoot through shower at gym
- getting pedicure done
- exploring cave or ruined building
- breathing
64
Fungi have 400 million species. Of these 400 million, how many are pathogenic?
300
65
What typically fends off most fungi?
a well-functioning immune system (our body temp is not ideal for fungi survival)
66
How are fungal infections typically acquired through?
spread of microscopic spores
67
Where do most fungal infections begin?
- skin (through contact)
- respiratory tract/lungs (breathing in spores)
68
Why are fungal infections on the rise worldwide?
1. global warming (increase in temp=warmer and damper environment for fungus to grow)
2. heat stress from global warming can make fungi more pathogenic
3. immunosuppression is becoming more common
4. increasing use of medical devices (catheters) that can be colonized by fungi
69
Likelihood of pandemic related to fungal infection is (1) due to method of transmission and innate ability to handle
low
70
In an immunocompromised individual, most fungi are (1)
1. pathogenic
71
What individuals are considered immunocompromised?
- congenital syndromes resulting in altered immune system
- HIV
- organ/stem cell transplant
- immunosuppressive medications
72
What are examples of congenital syndromes resulting in altered immune system?
- complement deficiencies
- B cell defects
73
What are some diseases where immunosuppressive medications are needed?
- Crohn's Disease
- lupus
- plaque psoriasis
74
What are more common in immunocompromised patients?
systemic mycoses
75
What are fungi that need keratin (skin, hair, nails) to grow?
dermatophytes
76
What do not generally grow in living tissue?
dermatophytes
77
What do dermatophytes typically cause?
dermatologic conditions
78
What may require skin/hair scraping, nail sampling or biopsy to diagnose uncertain cases?
dermatophytes
79
What does the terminology of dermatophytes start with?
Tinea
80
Intertrigo is a fungal infection with what?
Candida albicans
81
What does intertrigo flourish in?
warm, moist regions (under breasts)
82
What is another name for Tinea corporis?
ringworm
83
What is caused by dermatophyte (genera of Trichophyton and Microsporum) and spreads very easily?
Tinea corporis
84
Fungal skin infections typically respond to what treatment methods?
oral or topical antifungal treatments
85
What does not usually provide any clues to a fungal skin infection?
blood testing
86
If oral or topical antifungal treatments for fungal skin infections is ineffective or diagnosis in doubt, what can you do to examine the specimen?
- skin scraping
- KOH examination
87
What should you look for in skin scraping and KOH examinations?
- hyphae, pseudohyphae, budding yeast (branching hyphae)
88
Some benign pathogens (to normal immune system) may be fatal to who
HIV patient
89
In HIV and immunosuppression patients, fungi can be invasive to an (1) level?
organ
90
Fungal pneumonia can be found in who?
HIV and immunosuppression patients
91
If fungal pneumonia or fungal organisms such as pneumocystis jirovecii, cryptococcus neoformans, and histoplasma capsulatum is identified in a patient with an invasive infection, what should you check?
HIV status
92
What should you perform with patients with systemic mycoses?
perform a complete history and physical
93
What are the characteristics of patients with systemic mycoses?
- can be mildly to critically ill
- fungal infections commonly missed
- have higher suspicion in immunocompromised patients
94
In patients with systemic mycoses, what can you use to diagnose fungal infections?
- blood cultures
- tissue cultures
- other pertinent body fluids
95
Cultures for fungal infections grow (1)
slow
96
Because fungal infections grow very slow, what does this do?
- makes fungal infections harder to diagnose
- patients may have been treated with antibiotics but did not get better
