Bacteria, Fungi, Viruses and Parasites Flashcards
(143 cards)
1
Q
What are the different types of bacteria morphology?
A
Coccus- circle shaped, single, pairs, chains, 4s, 8s or clusters
Bacillus- rod shaped, single, chains or pairs, curved, helical, club shaped or filamentus
Coccobacillus- elongated ball
Pleomorphic- multiple possible shapes
2
Q
List the features of bacterial structure
A
Capsule Cell wall Plasma membrane Periplasmic membrane Inclusion bodies- nutrient store Ribosomes Mesosome- folding of membrane to keep proteins in place Neucleoid Flagellum Surface proteins Glycocalyx- capsules and slime layers Fimbrae- small extensions outside cell
3
Q
What is meant by protoplast?
A
Plasma membrane, cytoplasm and all its contents
4
Q
Describe how the gram positive cell wall works
A
Outside plasma membrane
Shrinks in dehydration to form full barrier around cell to conserve water
5
Q
What is the structure of the gram positive cell wall
A
Peptidoglycan cross link proteins stabilised by lipoteichoic acid and teichoic acid
6
Q
Describe where the gram negative cell wall is found
A
Surrounding plasma membrane is periplasmic space and then an outer membrane
7
Q
What is the structure of the gram negative cell wall?
A
Liposaccharides present in bilayer
8
Q
What is the structure of liposaccharides?
A
Lipid A linked into outer membrane connected to core chain and O specific side chain
9
Q
What is the function of chromosomal DNA in bacteria and where is it found?
A
Codes all functions
In nuclear region, usually only one present
10
Q
What are plasmids?
A
Extra chromosomal DNA
Usually auxiliary genes and carry antibiotic resistance
11
Q
Define auxiliary genes
A
Modulate host cell metabolism during infection to make replication efficient
12
Q
What are the types of plasmids?
A
Resistance Virulence- causes harm Colicin- toxic protein prodcuing Fertility- plasmid moves between bacteria Degradative
13
Q
What is the effects of genetic variation?
A
Evolution
Affects virulence, resistance to hosts defences and resistance to treatments
14
Q
What are the different methods of variation?
A
Affects resident genome- mutation, slowly happens and most lead to death
New DNA- recombination, rapid
15
Q
When is variation retained by bacteria?
A
When it causes increase in survivability
16
Q
What are the different nutritional requirements by different bacteria? Name an example for each and other important information
A
Simple- glucose, phosphate, sulphate, ammonium. e cColi. Tend to live in gut and make nutrients using lots of genes and pathways
Complex- growth factors, vitamins, nucleotides. Fastidious bacteria. Unable to make certain compounds due to less genes and pathways
Unknown needs- cant grow in lab, probable need lots of requirements from host. Parasites
17
Q
Define fastidious
A
Microorganism that must live in host to survive
18
Q
What is the oxygen requirement and energy production in obligate aerobes?
A
Lots of oxygen
Aerobic respiration
19
Q
What is the oxygen requirement and energy production in microaerophiles?
A
Some oxygen as unable to remove toxic products of oxygen metabolism
Aerobic respiration
20
Q
What are the oxygen requirements and energy production in facultative anaerobes?
A
Live with or without oxygen, lots of energy pathways
Aerobic respiration, anaerobic respiration and fermentation
21
Q
What are the oxygen requirements and energy production in strict anaerobes?
A
Die in oxygen
Anaerobic respiration and fermentation
22
Q
Define saprophytes
A
Free living bacteria
23
Q
Define parasites
A
Organisms that live in or on animals
24
Q
What are the two different sources of infections?
A
Exogenous- from environment or another host carrying commensals
Endogenous- from animals own commensals
25
Define symbiotic
Bacteria and host benefit from each other
26
Define commensal
Bacteria gain from host but cause no harm
27
Define pathogenic bacteria
Bacteria gain and cause harm, either obligate or facultative
28
What is meant by facultative bacteria?
Opportunistic
| Normally harmless until host conditions change
29
What are opportunities for facultative bacteria to cause harm?
Entry into new body site
Change in body site, temperature, pH, commensal imbalance etc
Reduced defences
30
What are the requirements for bacterial growth?
Slightly alkaline pH
Optimum temperature varies
CO2 from body catabolism or environment
Nutrients
31
What are the products of oxygen metabolism and why do they need to be mopped up?
Hydrogen peroxide and superoxide radical
| Destroy cell
32
What mops up the products of oxygen metabolism?
Hydrogen peroxide- catalase
| Superoxide radical- superoxide dismutase
33
Why cant anaerobes survive in oxygen?
They dont produce catalase or superoxide dismutase
34
What are the mechanisms of nutrient uptake by bacteria?
Passive diffusion- very slow, ineffective unless in nutrient rich environment
Facilitated diffusion- moves through channels
Active transport- uses lots of energy, need constant respiration or fermentation
35
What different types of medium can be used to provide nutrition in a lab to bacteria?
Simple- agar
Enriched- non-specific, grow everything present
Selective- mimics ideal conditions and inhibits other bacteria
Differential- visually differentiates bacteria colonies
Blood agar- shows if haemolytic
MacConkeys bile lactose agar- mimics gut growing bacteria that grow in bile
36
Describe bacterial growth in a closed system
Lag to start as bacteria adapting enzymes and proteins to new conditions
Exponential growth
Growth stationary as lack of resources
Decreases in number as bacteria starve or poison to death
37
Define obligatory parasites
Spend whole life in host to be able to reproduce, intermittent or continuous feeders
38
Define facultative parasites
Spend part of life in host, can reproduce on or off host, intermittent feeders
39
What are the general symptoms parasites have on the host?
```
Blood loss
Tissue damage
Inflammation
Itching
Allergic responses
Reduced weight gain
Skin wounds
Microbial infection
```
40
What animals is sarcoptic mange mainly found in and in which area of the body?
Dogs- pinnae, elbows and ventral abdomen
| Pigs- ear canals and dorsal trunk
41
How does sarcoptic mange spread?
Zoonotic
42
Why is sarcoptic mange hard to find after infection?
Mites are hard to find
| Can be asymptomatic for a long time
43
What are the symptoms of scabies/sarcoptes?
Intense itching
Infalmmation
Hair loss
Dry skin
44
Explain the life of scabies
Adult females burrow into upper skin layers and lay eggs
Eggs grow to adult in 17-21 days
Can survive 2-3 weeks off host but usually find new host after 2 days
Host dies after 2-4 months`
45
Define mange
Severe skin disease caused by ectoparasitic mites
46
List the life cycle of mites
```
Egg
Larvae
Protonymph
Deutonymph
Tritonymph
Adult
```
47
How do mites increase their size?
Slough off exoskeleton
48
What disease is caused by trombicula autumalis?
Pruritic skin disease
49
Describe the life cycle of trombiculidae
Large yellow larvae are found on vegetation mid-late summer and autumn particularly on soft fruits
Larvae attach to host and feed on tissue fluid
Fall off and finish life cycle in environment
50
What are the symptoms of trombiculidae?
Hypersensitivity and severe pruritus
51
Where does cheyletiella live?
Skin surface usually on hairs in rabbits, cats and dogs
52
How long can cheyletiella live off the host?
10 days
53
What are the symptoms of cheyletiella?
Irritation
| Highly contagious dermatitus
54
What hosts does otodectes cynotis live in and where are they found?
Cats
Dogs
Carnivores
Ear canal
55
How long to females otodectes cynotis live and how many eggs can they produce?
2-3 weeks
| 15-20 eggs
56
Where is demodicosis found and how can they be found?
Deep in skin in sebaceous glands and hair follicles
| Deep skin scrapes, hair plucks or biopsy
57
What type of parasite is demodicosis?
Obligate parasite
58
How long do demodicosis live and how are they passed on?
18-24 days
| Dam suckling from mum
59
What is meant by ticks questing?
Crawling up vegetation and waiting for host to come close to climb on
60
Describe the lifecycle of a tick
```
Adult female engorges
Lays eggs after blood feed
Larvae
Nymph
Adult
```
61
What makes ticks effective at holding onto their host?
Backward facing teeth
62
Why do ticks cause inflamation?
Saliva contains vasodilative prostaglandins
63
Describe the lifecycle of ixodes ricinus tick
```
Adults feed on cattle
Fully fed adult drops
Lays eggs which hatch in ground
Larvae feed on rodents or birds
Fully fed larvae drops to ground
Moults to lymph
Nymphs feed on small animals
Fully fed nymph drops to ground
Nymph moults to adults
```
64
Describe the lifecycle of fleas
Adult lays eggs 48 hours after mating and feed
Larvae hatches 1-10 days after laying
Move away from light to feed on organic debris
Pupa forms ater 5-11 days, spinning cocoon and staying deep in carpets for weeks-months
Adult usually emerges after 5-10 days to look for host and blood meal
Once on host must feed as gut changes and can only survive 3 days away from host
65
How long can unfed fleas survive?
10-60 days
66
What symptoms do fleas cause?
```
Pruritus/itching
Alopecia
Self wounding
Hypersensitivity
Anaemia
```
67
What adaptations do lice have?
3 pairs of legs- hold hair
Short pointed head- penetrating to feed
Flat head- chewing epidermis
68
Describe the life cycle of lice
Egg layed on hairs
Nymph
2 sheds and growth
Adult
69
What are the different types of lice?
Felicola subrostratus
| Trichodectus canis
70
What makes animals more vulnerable for felicola subrostratus?
Elderly
Ill
Long haired breeds is harder to manage
71
Where is trichodectes canis found?
Base of hairs at head, neck and tail
72
What does a trichodectes canis infection cause and what animals is it most harmful to?
```
Itching
Inflammation
Alopecia
Bacterial infection
Intermediate host of tapeworm
Puppies
```
73
What classifications of flies are there?
```
Dermal
Subdermal
Cutaneous
Nasopharyngeal
Ocular
Intestinal
Urogenital
```
74
Describe the lifecycle of gasterophilus spp. flies
```
Lay eggs on horses
Get ingested and larvae swallowed
Larvae reside in stomach
Released in faeces
Grow into adults in the environment
```
75
What are culicoides flies?
Small flies acting as vectors for alicoides hypersensitivity
76
What animals are common hosts for culicoides flies?
Horses
77
What is the vectors for canine leishmaniosis?
Sand flies
78
What is the life cycle of culicoides midges?
Egg
Aquatic larvae, stay as 4th stage larvae over winter
Pupa
Adult which can live 20 days in field
79
What are common rabbit parasties?
Blowfly strike
Myxomatosis
Mange mites
Coccidia
80
What causes rabbit strike?
Lucillia sericata when rabbits struggle to groom and cause skin damage that flies lay eggs in
81
What is strongyles and where is it found?
Large redowrm in horses gut
82
Describe the lifecycle of strongyles
```
Eggs layed in gut
Leave in faeces
Grow into larvae in environment
Continue to grow as larvae when ingested by horse
Mature in gut
```
83
How does strongyles cause disease?
Block blood vessels in gut causing colic
84
What are the common equine parasites?
```
Parascaris round worms
Tapeworms
Bot flies
Midges
Fly worry
```
85
What is anthelmintic resistance and what parasites have it?
Resistance to anthelmintic drugs from repeated infection and treatment
Widespread in redworm, parasacris and pinworms
86
What is cyathostomins and where are they found?
Small redworms
| Horses gut
87
How does cyathostomins cause disease?
Larvae damage mucosa on emergence
88
What are the clinical signs of angiostrongylus?
```
Coughing
Dyspnoea
Anaemia
Depression
Anorexia
Pneumonia
Weightloss
Pulmonary hypertension
```
89
Where is toxocara canis found?
Dogs and cats small intestines
90
Describe the lifecycle of toxicara canis
Lay eggs in faeces which are ingested
| Grow and leave gut and enter liver and lungs
91
Describe the lifecycle of family taenidae
Adult tapeworms sit in gut and lay eggs in carnivores
| Immature stage when eggs are ingested cause cysts in various organs of herbivores
92
What is the cell wall of fungi?
Chitin and complex carbohydrate polymers
93
What are the two main forms of fungi?
Mould
| Yeast
94
Define dimorphic fungi
Produce both yeast and hyphae
95
Define and describe pseudomycelium
Intermediate form of growth between hypahe and yeast
| Elongated budding cells from pseudohyphae
96
Define a colony of fungi
Mycelium or mass of yeast cells usually grown from a single cell
97
Define hyphae
Basic unit of moulds
98
Describe the structure of hyphae
Atypically elongating cylinder capable of branching
Cross walls at intervals to add strength but pores in to allow sharing of cytoplasm and nutrients
Acellular often having several nuclei per segment
99
Define mycelium
Network of hyphae forming body of mould
100
What are the two types of mycelium?
Submerged vegetative- burrowed into surface
| Aerial- in air
101
How do moulds reproduce?
Release spores
| Asexual
102
How do yeasts reproduce?
Budding
103
Where do yeasts live?
On surfaces
104
What is the structure of yeast cells?
Discrete ovoid cells
105
What are the phylums of fungi?
Zygomycota
Ascomycota
Basidomycota
Deuteromycota
106
What type of fungi fit into deuteromycota?
Fungi that dont fit into other phylum groups
| Most pathogens
107
What are features of deuteromycota?
No sexual reproductive state, only produce conidia
108
How are fungal diseases diagnosed?
Skin scrapes
Culture and ID
Serology of antibodies
Molecular ID of fungal DNA by PCR
109
How are fungi introduced to the body?
Mycosis/infection
Inhaled
Toxicosis/ingesting
110
What are the two sources of fungal infection?
Endogenous- commensal flora, fungal overgrowth
| Exogenous- fungus taken into body
111
What are the types of fungal infections?
Superficial- epidermis, nails, hair
Subcutaneous- traumatic inoculation through skin
Deep- inhaled, deep wound, endogenous
112
What are features of deep fungal infections?
Grow well at blood temperature
Not contagious as dont grow well enough to pass between individuals
Opportunistic
113
What are examples of yeast infections?
Candidosis- thrush
Cryptococcosis
Malassezia- cause dandruff
114
What are examples of mould infections?
Aspergillosis
Mucoromycosis
Mycotic abortion
115
What symptoms does cattle ringworm cause?
Loss of growth
Lower milk yield
Scarring (reduce value)
116
What treatment is used for cattle ringworm and why is it easy to treat?
Topical shampoos, washed or sprays
Decontaminate environment by burning, restricting movement and bleaching
Asexually reproduce so little variation
117
What is bovine mycotic abortion?
Non-contagious infection of placenta and foetus causing thickening of membranes and skin
118
What is candidosis?
Opportunistic infector found in normal gut flora
119
How is cryptococcosis spread and how does it cause disease?
Inhaled
Nasal granuloma, skin ulcers, mastitis
Opportunistic
120
What is the main source of aspergillosis?
Spores in hay and straw
121
How does aspergillosis cause disease?
Inhaled and travel to alveoli
Hyphae go into tissues
Acute in young as easily takes over airways, chronic in young animals
122
How were viruses first discovered?
Thought to be toxin, dilution didnt effect disease severity but less got infected overall
Foot and mouth disease was transmitted after bacterium had been removed
123
What does genome sequencing of viruses help understanding of?
```
Classification
Replication
Development of drugs
Vaccines
Evolution
```
124
How are viruses grown in labs?
In living tissues such as embryonic eggs or animal cells
125
How are viruses seen in labs?
Electron microscopes
126
Why cant viruses live outside host cells?
Rely on them for energy source, raw materials and machinery for replication
127
What are the structural components of viruses?
```
Genome
Peplomers- virus derived proteins anchored in virus envelope
Envelope- lipid bilayer
Proteins
Capsid
```
128
What are the features of viral genome?
No genes for energy metabolism
No protein synthesis enzymes or ribosomes
No genes for lipid or amino acid synthesis
Few introns
129
What are the possible structures of viral DNA?
Double stranded
+ve sense- directly translates to protein
-ve sense- translated after being copied into +ve sense
130
What is the common peplomer of viruses and what is their role?
Glycoproteins- sugar added by host enzyme in golgi
Adhere to host cells surface in first stage of infection
Gives specificity of virus
131
How is viruses envelope formed?
From host by budding within cell
132
Define nucleocapsid and explain its role
Capsid and nucleic acid together
Protect nucleic acid from UV light, nucleases
Provide attachment
Packages genome and essential enzymes
133
What are the two methods of capsid structures of viruses?
1- sheet rolls into cylinder with proteins forming spiral pattern and ends round over to close
2- pentagon in centre surrounded by hexagons leaving gaps whihc close to form football
134
How do viruses capsid sheets form?
Hexagon proteins surrounded by 6 more
135
Define viral pathogenosis?
Process viruses cause disease
136
What are the routes of viral infections and what type of infections are common with them?
Respiratory- upper respiratory epithelial cell infections, later systemic disease
Oral- intestines, systemic disease
Percutaneous- injection through skin
Cutaneous- entry through skin, localised but can become systemic
Sexually transmitted- localised or systemic
137
Explain highly specific viral infections
Interaction between cell and virus needs exact complementary fit limiting the cells and virus types involved
138
Explain non-specific viral interactions
Viruses bind to proteins common on many cell types allowing wide host potential
139
What is the effects of viruses on the host?
Inflammatory response caused by interferon, pro-inflammatory cytokines and chemokines
140
What are symptoms of virus infection?
```
Fever
Decreased motor activity
Reduced responsiveness
Reduced food and water intake
More sleep
Altered cognition
Increased pain sensitivity
```
141
How is the effect of viruses on cells determined?
How it alters, uses and leaves the cells
142
What are the two effects of viruses on cells?
Lytic infection- cause cell death when virus leaves cell, complete loss of function
Latent infection- virus persists in cell without causing death, alters growth and division, virus leaves by budding
143
What effects can latent viral infections have?
Persistent infection- failure of immune system to clear infection
Enhanced cell growth- virus manipulates cell growth causing tumour formation
