Exam 4 Flashcards
1
Q
fungal disease: community-acquired
A
infections caused by environmental pathogens
2
Q
fungal disease: hospital-associated
A
infections caused by fungal pathogens in clinical settings
3
Q
fungal disease: opportunistic infections
A
caused by low-virulence species infecting already-weakened individuals
4
Q
Dermatophytes
A
Unique group of fungi that infect keratinous tissue and are able to invade the hair, skin, and nails of a living host
(a) Athlete’s foot. (b) Ringworm on a child’s face and (c) on an adult index finger.
5
Q
Dermatophytes: Genus Examples
A
- Microsporum
- Epidermophyton
- Trichophyton
Causes: Ringworm, athlete’s foot, jock itch, fungal nail bed infections
among others
6
Q
Cryptococcosis
A
A pulmonary or disseminated infection acquired by inhalation of soil contaminated with the encapsulated yeasts.
7
Q
Cryptococcus neoformans
A
- Infection commonly associated with
immunosuppressive - Meningitis and meningoencephalitis
8
Q
Cryptococcus gatti
A
- Infections NOT associated with
immunosuppression
9
Q
Aspergillosis
A
An infection caused by Aspergillus species, a common mold
10
Q
Aspergillus species
A
- Ubiquitous in the environment
- Mainly in immunocompromised individuals
11
Q
Aspergillus fumigatus
A
most prevalent and is largely responsible for invasive aspergillosis with a very high mortality rate
12
Q
Aspergillus flavus
A
synthesizes a poison called aflatoxin,
potentially lethal to animals who eat contaminated grain
- can lead to acute hepatitis, immunosuppression, hepatocellular
carcinoma, and neutropenia (LIVER ISSUES)
13
Q
Ophiocordyceps unilateralis
A
“Zombie-ant fungus”
- Insect-pathogenic fungus
- Predominantly in tropical
forest ecosystems
- Genus examples: Other members of Cordyceps and Ophiocordyceps also
parasitize insects
14
Q
Histoplasmosis
A
“Ohio Valley Fever”
15
Q
“Ohio Valley Fever”
A
Caused by the fungus Histoplasma capsulatum
- * Not contagious so it can’t be spread from person to person
* Primarily affects lungs
→ symptoms similar to pneumonia
- Naturally found in soil, often associated with bat or bird droppings
- In Latin America and the Caribbean, histoplasmosis is one of the most
common infections among people living with HIV
- 75% of adults who
live in areas where H. capsulatum is common have been infected before
15
Q
Candidiasis
A
A fungal infection typically on the skin or mucous membranes caused by a yeast – Candida
- Residential flora
* Found on skin, mouth, throat, gut, and vagina
15
Q
Ergot: a group of fungi in the genus Claviceps
A
Most commonly Claviceps purpurea
15
Q
Candida albicans (most common)
A
Opportunistic pathogen
* Thrush, vaginal yeast infection,
cutaneous candidiasis
16
Q
Ergotism
A
Poisoning produced by eating food affected by ergot
- gangrene of the fingers and toes
- Also known as: Saint Anthony’s Fire,
ergotoxicosis, or ergot poisoning
- Infects rye and other cereals
17
Q
Aflatoxins are produced by?
A
Aspergillus
18
Q
Which of the following structures would NOT be associated with fungi?
A
chloroplasts
19
Q
Ergosterol synthesis is often the target of anti-fungal drugs T or F
A
True
20
Q
Claviceps can cause several effects in humans and other animals, such as
hallucinations and gangrene. It is usually ingested by contaminated?
A
Grain
21
Q
Which of the following fungi are the cause of ergotism?
A
Claviceps
22
Algae
A group of photosynthetic organisms
- Widespread in both fresh and marine waters
- Contribute significantly to oxygen content of the atmosphere through photosynthesis
23
Algae what organelles?
chloroplasts
24
Diatoms
One of the most prevalent groups on Earth are the single-celled diatoms
25
Cell wall of diatoms?
contains silica
26
Diatoms high diversity
High diversity is useful in forensics in analyses of bodies of water
27
Forensic Limnology
the study of freshwater ecology for the presence of diatoms (particularly) in order to solve forensic and medical cases
28
Diatoms with silica
Cosmetic products, Used as an insecticide, Structural Materials
29
Prototheca: infections algae
- associated with skin and subcutaneous infections in humans and animals
- infection rare, most of the time just toxic
30
Prototheca
- Only recognized as human and animal pathogens in the 1960s
- First human outbreak in 2018
- No effective drugs
31
Dinoflagellates (made toxin)
Can cause algae blooms
- Red tides – marine species
- Intertidal animals feed → accumulate toxins given off
by algae
32
Paralytic shellfish poisoning (causes)
caused by eating exposed clams or other invertebrates
33
Ciguatera (toxin)
a serious intoxication caused by algal toxins that have accumulated in fish
34
Protozoa
“first animals”
- 12,000 species of single-celled creatures
- Most are harmless, free-living inhabitants of water and soil
- few species are pathogens
35
Protozoan Form and Function
- Single cells containing all of the major eukaryotic organelles
- Cytoplasm divided into two parts: ectoplasm and endoplasm
36
Ectoplasm
clear outer layer involved in locomotion, feeding, and protection
37
Endoplasm
granular inner region housing the nucleus, mitochondria, and food and contractile vacuoles
38
Protozoan Form and Function cont.
- Some organelles act as a primitive nervous system to coordinate movement
- Can move through fluids by means of pseudopods (“false feet”)
- Cell membrane
- Cell shape can remain constant (as in most ciliates), or change constantly (as in amoebas)
39
Protozoa Nutritional and Habitat Range
- Heterotrophic
- Free-living species scavenge dead plant or animal debris or graze on bacteria and algae
- Some have special feeding structures, such as oral grooves
40
Nutritional and Habitat Range cont.
Main limiting factor is availability of moisture
- Predominant habitats are fresh and marine water, soil, plants, and
animals
- can survive in non moist areas but don't always grow
41
Life Cycles: Protozoa
Trophozoite (all can be)
Cyst (some)
42
Trophozoite
motile feeding stage requiring
ample food and moisture to stay active
43
Cyst
Dormant, resting stage when conditions in the environment become unfavorable
* Resistant to heat, drying, and chemicals
* Can be dispersed by air currents
* Important factor in the spread of disease
44
Alternating?
Many alternate between the trophozoite and cyst
stage, depending on the habitat
45
Reproduction: Protozoa
All protozoa reproduce by relatively
simple, asexual mitotic cell division
or multiple fission
46
Sexual reproduction also occurs in most protozoa (they want to)
* Ciliates participate in conjugation in
which two cells fuse and exchange
micronuclei
* Results in new and different genetic
combinations → can be advantageous in evolution
-2 organisms connecting
47
Trichomoniasis
(causative agent Trichomonas vaginalis)
Common STI
- Antibiotic treatment is usually very successful
- Trich can increase the risk of getting or spreading other STIs
Men:
mostly asymptomatic
Women:
symptomatic
- survive for several hours on moist
surfaces and up to a day in urine or
semen
- contaminated fomites,
such as toilet seats, sauna benches, and towels
48
African Trypanosomiasis
(Sleeping Sickness)
Vector: tsetse fly
- Drowsiness, Insomnia, Sleepiness
- painful nodule at site of fly
bite
49
causative agent: Trypanosoma brucei
Vector: tsetse fly
- Treatment should be early
- enters lymphatic system
50
Chagas Disease (American Trypanosomiasis)
causative agent Trypanosoma cruzi
51
Chagas Disease (American Trypanosomiasis) cont.
- Latin America
- Vector: Triatomine bugs, known
as 'kissing bugs'
- transmitted by feces of the insect (bites face)
52
Chagas Disease (American Trypanosomiasis): acute and chronic
* acute: maybe asymptomatic or
mild like fever, malaise
* followed by remission – no
symptoms for many years
* chronic: includes digestive
problems and heart failure
- treat early
53
Giardia causative agent
Giardia intestinalis
54
Giardia
Most frequently diagnosed intestinal parasitic disease in the United States
- Transmitted via contaminated sources or fecal-oral route (hands or fomites)
- The thick-walled cysts are resistant to chlorine
- most outbreaks have been associated with water systems that
used only chlorination as a means of water purification
55
Giardia
- form cyst
- Cysts are hardy and can survive several months in cold water
- The chances of people getting a Giardia infection from dogs or cats are small
56
Amoebic dysentery - Amebiasis causative agent
Entamoeba histolytica
57
Amoebic dysentery - Amebiasis
- untreated sewage is allowed to enter surface waters
- Parasite only lives in humans and is passed via feces
- Commonly asymptomatic (9/10)
- no vaccine, but treated with drugs
- common for reinfection because it does not confer immune memory
58
Primary amebic meningoencephalitis (PAM) causative agent
“Brain-eating Amoeba” →Naegleria fowleri
- Warm fresh water and soil
- Enters the body through the nose → travels to the brain → extensive hemorrhage and brain damage
- Otherwise....nearly always fatal (>97% mortality rate)
59
Acanthamoeba
keratitis
Rare, but severe infection of the eye (cornea)
- Can result in permanent visual impairment or blindness
- More common in people who wear contact lenses
60
Acanthamoeba
keratitis causative agent
Acanthamoeba → free-living ameba
* Found in bodies of water, soil, and air
61
Balantidiasis causative agent
Balantidium coli
62
Balantidiasis
The only ciliate known to be capable of infecting humans
- Often associated with swine → primary reservoir host
* Humans can also be reservoirs, and other potential animal hosts include rodents and nonhuman primates
- Cysts are the stage responsible for transmission
- Mostly asymptomatic, sometimes a perforated colon
63
Toxoplasmosis causative agent
Toxoplasma gondii
64
Toxoplasmosis
Cat litter box disease; contaminated food and water
- Severe infections more likely in newborn
- 1-5 days to become infectious
65
Cryptosporidiosis “Crypto” disease (commonly confused)
Leading cause of waterborne disease among humans in the United States
- Can survive long periods of time outside host
* Protected by an outer shell
* Tolerant to chlorine disinfection
- Water is the most common method of transmission
-
66
Leading cause for human infection
Cryptosporidium parvum and Cryptosporidium hominis
- leading cause of pediatric
diarrhea worldwide, and it is responsible for nearly 9% of fatalities due to infectious disease in children
67
Malaria causative agent
Plasmodium
- 5 species that cause malaria in humans
* P. falciparum and P. vivax most threatening
68
Malaria
Vector: female Anopheles mosquitoes
* Resistance to antimalarial medicines is a recurring problem
* Can be controlled by eliminating mosquitoes
69
Flagellates that infect the genital tract?
Trichomonas vaginalis
70
Which of the following is the same for both Trypanosoma cruzi and Trypanosoma brucei and the infectious diseases they cause?
Importance of early diagnosis
and treatment
71
Which of the following is thought to be one of the agents of frequent cause of non-bacterial diarrhea in
North America?
Giardia
72
The Helminths
tapeworms, flukes, roundworms
- Adult specimens are usually large enough to be seen with the naked eye
- microscope for eggs/larvae
- many live free in soil and water
~50 species cause disease in humans
- Disease-causing helminths spend part of their lives in the gastrointestinal tract
73
Flatworms
tapeworms and flukes
- often segmented
74
Roundworms
unsegmented body
75
General Worm Morphology
- Multicellular animals that are equipped to some degree with organs and organ systems
76
pathogenic helminths
- the most developed organ is the
reproductive tract
- therefore, there is a reduction in the digestive, excretory, nervous,
and muscular systems
77
Life Cycles and Reproduction: pathogenic helminths
fertilized egg, larval, and adult stages
- adults reproduce in host, reproduce sexually
- Helminth sexes can be separate sexes (visually similar or distinct) or
hermaphroditic
78
Helminth life cycle
infective form (egg or larva)
- larva develops is known as the intermediate (secondary) host
- Adulthood and mating occur in the definitive (final) host
- Transport host is an intermediate that experiences no parasitic development
- contaminated food, soil, and water or infected animals
79
Egg Laying: Helminths
Vulnerable to heat, cold, drying, and
predators
- protective shell and extra
food
- Certain helminths can lay from 200,000 to 25 million eggs a day to assure successful completion
of their life cycle
79
Taeniasis
tapeworms by eating raw or undercooked beef (Taenia saginata) or pork (Taenia solium and Taenia asiatica)
79
beef
Taenia saginata
80
pork
solium and asiatica
81
Taeniasis causative agent
(Taenia saginata) and (Taenia
solium and Taenia asiatica)
82
Taeniasis symptoms
symptoms are usually mild or nonexistent
- abdominal pain, loss of appetite, weight loss, and upset stomach
- visible sign of taeniasis is the active passing of proglottids (tapeworm segments) through the anus and in
the feces
- segments become lodged in the appendix, or the bile and pancreatic ducts
- Taenia solium infections can lead to cysticerosis, which is a disease that can cause seizures
83
Ascariasis causative agent
Ascaris lumbricoides
84
Ascariasis
most common human worm infection
- The larvae and adult worms live in the small intestine and can cause intestinal disease
- nasty for children
85
Schistosomiasis (Bilharzia) causative agent
Schistosoma mansoni, S. haematobium, or S. japonicum
86
Schistosomiasis (Bilharzia)
Second only to malaria as the most devastating parasitic disease (CDC)
- NTDs (neglected tropical disease)
- Contact with freshwater with certain snails
- enlarged liver, blood in the stool
87
Elephantiasis (Bancroft’s filariasis) causative agent
Wuchereria bancrofti - nematodes
88
Elephantiasis (Bancroft’s filariasis)
Vector: Mosquitoes
- Adult worm lives in lymph system
- Interrupts lymph flow
- Lymphedema swelling of mainly legs, but can also affect arms, breasts, and genitalia
- hardening and thickening of skin
89
The most developed organ system in helminths is the?
reproductive
90
Virus
a genetic element that contains either RNA or DNA surrounded by a protein capsid and that replicate only
inside host cells
91
Viruses
Virus is Latin for “poison”
- Most abundant biological entities on Earth
- not alive
- most abundent
- infect every type of cell, including bacteria, algae, fungi, protozoa, plants, and animals
92
Viruses
- Needs host cell for energy, metabolic intermediates, protein synthesis
- their own nucleic acid genome
93
Discovery of Viruses
For many years, the cause of viral infections was unknown
- Louis Pasteur hypothesized that rabies was caused by a “living thing” smaller than bacteria
- 1884 → developed the first vaccine for rabies
94
Filterable virus
fluids from host organisms passed through porcelain filters designed to trap bacteria, the filtrate remained infectious
- This proved that an infection could be caused by a fluid containing agents smaller than bacteria
95
Filterable virus
Dmitri Ivanovski and Martinus Beijerinck showed that a disease in tobacco (plant virus) was caused by a virus
- Loeffler and Frosch discovered an animal virus that causes foot-and-mouth disease in cattle
96
How did viruses originate?
1. Progressive Hypothesis
- Escaped genes
exit one cell and enter another
- evidence is retroviruses (HIV)
97
2. Regressive Hypothesis: Reductive evolution
lost genetic information
over time
- Adopted a parasitic approach to replication
- evidence is Nucleocytoplasmic large DNA viruses (NCLDVs)
98
3. Virus first
Viruses may have existed in a precellular world as self-replicating units
- evidence some viruses have only RNA
- Nucleus as a result of an endosymbiotic-like
99
Are they organisms; that is, are they alive?
some traits of life
- rely on host
- do not consider them cells or alive
- described as either active or inactive
100
What role did viruses play in the evolution of life?
Infect cells and influence their genetic makeup
- Shape the way cells, tissues, bacteria, plants, and animals have evolved
- 8% of the human genome consists of sequences that come from viruses
- 10 to 20% of bacterial DNA contains viral sequences
- Obligate intracellular parasites: invade a specific host cell and instruct its genetic and metabolic machinery to make and release new viruses
101
What are their distinctive biological characteristics?
- animal viruses were classified on the basis of their hosts and the
diseases they caused (Old System)
- Newer classification systems
structure, chem composition, DNA and RNA makeup
102
Properties of Viruses
- obligate intracellular parasites
- ubiquitous in nature and have had major impact on development
- 10 times the number of bacteria and archaea combined
-ultramicroscopic in size
- Are not cells
- protein shell (capsid) surrounding nucleic acid core
103
pandora virus and mimivirus (largest)
(smallest known bacteria are rickettsia)
- Nucleic acid can be either DNA or RNA, but not both at the same time
- spikes: virus surfaces give them high specificity for attachment to host cell
- Multiply by taking control of host cell’s genetic material
104
resemble cells?
Viruses bear no resemblance to cells
105
How much of the human genome consists of viral sequences?
8%
106
Viral Components
1. External coating
2. Core containing nucleic acids (DNA or RNA)
3. Matrix proteins and enzymes
(occasionally)
107
naked virus
nucleic acid and capsid (nucleocapsid)
108
enveloped virus
envelope, phospholipid bilayer from host, nucleocapsid
109
Nucleocapsid
nucleic acid + protein in
enveloped viruses
110
Enveloped
viruses have an outer layer
consisting of a phospholipid bilayer (from host cell membrane) and viral proteins
111
Naked
viruses have no other layers
112
Capsid
the protein shell that surrounds the
genome of a virus
113
Spikes
can be found on naked or
enveloped viruses:
* Project from the nucleocapsid or the envelope
* Allow viruses to dock with host cells
114
Viral Capsid
Most prominent feature of viruses
- Constructed from identical protein
subunits called capsomeres
- Capsomeres spontaneously self-assemble into the finished capsid
- Two primary types:
1. Helical
2. Icosahedral
115
Complex Capsid Structure
Complex capsids, only found
in the viruses that infect bacteria
- They are never enveloped
116
Viral Envelope (on some)
Take a bit of the cell membrane when released
- More flexible than the capsid so enveloped viruses are pleomorphic
117
How can particles so small, simple, and seemingly insignificant be
causing disease and death?
>
118
Nucleic Acids
The Core of a Virus
119
genome
Having a larger genome allows cells to carry out the complex
metabolic activity necessary for independent life
- Viruses typically possess only the genes needed to invade host
cells
120
Multiplication Cycles in Animal Viruses
Viruses are minute parasites that seize control of the synthetic and genetic machinery of cells
General phases:
1. Adsorption - attach
2. Penetration
3. Uncoating - envelope has to be
4. Synthesis - make more
5. Assembly
6. Release
- The length of the replication cycle varies
121
Adsorption
A virus can invade its host cell only through making an exact fit with a specific host molecule
- Host range: the limited range of cells that a virus can
infect
122
Penetration and Uncoating
Direct fusion of the viral envelope with the host cell membrane (virus gets absorbed):
- Envelope merges directly with the cell membrane
Endocytosis (engulf) virus cell:
- penetrated by the whole virus or its nucleic acid
- entire virus is engulfed by the cell and enclosed in a vacuole or vesicle
123
Synthesis: Replication and
Protein Production
DNA viruses:
* Enter the host cell’s nucleus and are replicated and assembled there
RNA viruses:
* Replicated and assembled in the cytoplasm
124
Assembly and Release
* Size of the virus
* Health of the host cell
125
Maturation and Release of Enveloped Viruses
Budding of enveloped viruses causes them to be shed gradually, without the sudden destruction of the cell.
126
What is the connection between viruses and cancer?
Persistent Infections:
- carrier relationship
127
Provirus
Viral DNA incorporated into the DNA of the host
- Measles virus. HIV.
128
Chronic latent state
Periodically become activated
- (chickenpox and shingles)
129
Viruses and Cancer
permanently alter its genetic material
* Many times, leading to cancer (oncogenic)
130
Cancer-causing viruses
oncogenic
131
cancers are caused by viruses
13%
132
Transformation
- Some viruses carry genes that directly cause cancer
- Other viruses produce proteins
133
Transformed cells
1. Increased rate of growth
2. Changes in their chromosomes
3. Changes in cell’s surface molecules
4. Capacity to divide indefinitely
134
Oncoviruses: mammalian viruses capable of initiating tumors
* Papillomaviruses
* Herpesviruses
* Hepatitis B virus
135
Viruses That Infect Bacteria
Bacteriophage: “bacteria eating”
136
Bacteriophage
infects the bacteria then can infect you
137
T-Even Bacteriophage
Most widely studied phages
- Infect Escherichia coli
138
Bacteriophages
- all phages can enter into lytic
- some enter lysogenic state
139
temperate phages
can enter into lysogenic
- can enter prophage state
140
induction
exit of lysogenic stage
- goes straight to step 3 of lytic cycle
141
The Role of Lysogeny in Human Disease
phage genes in the bacterial chromosome can cause the production of toxins or enzymes that the bacterium would not otherwise have
142
Lysogenic conversion
when a bacterium acquires a new trait from its temperate
phage
-diphtheria toxin
-cholera toxin
-botulinum toxin
