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IMED2001 UWA > Lecture 7 Gram positive bacilli > Flashcards

Lecture 7 Gram positive bacilli Flashcards

1
Q

What features are gram positive rods classified with?

A

Their relationship with oxygen

Endospore formation

Morphology: regular, irregular, or filamentous and branching

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2
Q

How does oxygen affect gram positive rods?

A

Some are aerobes and/or facultative anaerobes

Some are strictly anaerobic

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3
Q

How do gram positive rods differ in endospore formation?

A

Some are endospore forming

Some are non-endospore forming

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4
Q

What can be said about bacillus oxygen usage and endospore formation?

A

Bacillus species are both endospore forming and aerobic

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5
Q

How many species are there of bacillus?

A

> 60

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6
Q

What can be said about the ecological niches of bacillus?

A

Very diverse ecological niches

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7
Q

Are bacillus species harmful to humans?

A

most species are non-pathogenic

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8
Q

What are the members of the bacillus cereus group?

A

IMPORTANT:
[Bacillus cereus
Bacillus thuringiensis
Bacillus anthracis]

GOOD FOR EXTRA MARKS:
Bacillus wiehenstephanensis
Bacillus mycoides
Bacillus pseudomycoides

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9
Q

What do molecular studies reveal about the bacillus cereus group?

A

They are part of the same species. Their phenotypic differences are caused by plasmid genes.

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10
Q

What does bacillus cereus do?

A

Food poisoning (caused by reheating of rice dishes)

Produced by enterotoxins

Associated with reheated rice dishes

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11
Q

What is bacillus thuringiensis used for?

A

Used as an insecticide

Used to control “river blindness” which is caused by onchocerca volvulus and simulium “black flies”

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12
Q

How does bacillus thuringiensis carry out the action it is used for?

A

Produces protein crystals which destroy the gut function of certain insects.

The code for these protein crystals is found on cry genes

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13
Q

What genes are derived from bacillus that can be used in crop genomes to make them insect resistant?

A

cry genes (500 differnet genes)

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14
Q

What is bacillus anthracis?

A

Soil organism that causes zoonotic infection in sheep, goats, horses, and wild animals

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15
Q

How is bacillus anthracis distributed?

A

Worldwide where it is mostly sporadic in occurrence but in some places it is hyperendemic

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16
Q

Where is anthrax typically found in Australia?

A

Around the anthrax belt through central NSW and in some locations of Victoria remains the main focus of human and animal cases in Australia.

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17
Q

What are the main virulence factors of bacillus anthracis?

A

Capsules that protect from host’s immune system

Spores that maintain survival in the environment in infective form which may remain viable for >100 years

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18
Q

How do humans get anthrax?

A

Humans acquire it when they come in contact with infected animals, their meat or other animal products

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19
Q

What are the transmission routes of anthrax?

A

Cutaneously through breaks in the skin

Inhalational through aerosols or dust

Ingestion through contaminated meat

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20
Q

What are potential complications of bacillus anthracis?

A

Could cause meningitis and septicaemia

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21
Q

What is the most common form of anthrax?

A

Cutaneous anthrax

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22
Q

How do bacillus transition in their lifecycle?

A

papulae -> Vesicles -> ulcer -> eschar

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23
Q

What percentage of people infected with cutaneous anthrax end up dying from it?

A

Untreated mortality is 10 - 40% of individuals

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24
Q

What is an eschar?

A

A black scar which has a ring of cellulitis around it

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25
What parts of the body does inhalational anthrax damage?
Haemorrhagic necrosis of perihilar and other lymph nodes.
26
What does skin look like that is infected by anthrax?
An eschar forms with red cellulitis around the ring
27
What is the mortality percentage of people infected by inhalational anthrax?
If not treated it kills 100% of people
28
What are the symptoms of GI anthrax?
causes inflammation, swelling and haemorrhage from mouth to caecum
29
What percentage of people affected by GI anthrax die from it?
Up to 50%
30
What can be said about oxygen usage capacity and spore formation of clostridium species?
They are endospore forming anaerobes
31
What are the important species of clostridium?
Clostridium perfringens Clostridium tetani Clostridium botulinum Clostridium difficile
32
Do spores persist in the environment?
Yes and they are the infective form
33
What kind of features make clostridium produce disease?
They produce toxins
34
What are the 5 types of toxins that clostridium perfringens produce?
A B C D E
35
What are the toxins produced in gas gangrene and food poisoning by clostridium perfringens?
Alpha toxin
36
What are the toxins produced by enteritis necroticans causing clostridium perfringens?
Alpha and beta toxins
37
How does gas gangrene occur?
Spores enter into open or traumatic wounds
38
How does gas gangrene kill?
Clostridium perfringens rapidly invade and liquefy muscle (liquefactive necrosis) and surrounding tissue
39
Why is it called gas gangrene?
Pathogenic clostridium perfringens produce gas in the tissue they destroy
40
What type of toxin is produced in gas gangrene?
Alpha toxin
41
What type of toxin is produced in type A clostridium perfringens?
A very potent enterotoxin is produced during spore formation in small intestine
42
What are the symptoms of clostridium perfringens in GI tract?
Crampy abdominal pain Diarrhoea Self limiting
43
What causes Necrotising bowel disease?
Ingestion of contaminated food with food rich in trypsin inhibitors
44
What causes damage during necrotising bowel disease?
Necrosis of bowel or bowel segment caused by beta toxin not being broken down due to trypsin inhibition
45
What is another name for necrotising bowel disease?
Pig bel
46
Why is necrotising bowel disease also called pig bel?
People in papua new ginea ate pig meat that wasn't completely cooked with clostridium perfringens spores in them as well as sweet potatoes causing that disease
47
What type of disease is enteritis necroticans?
Type C
48
Where are clostridium tetani spores typically found?
Spores found in the soil
49
How does tetanus get into the body?
through wounds and then they germinate
50
How do clostridium tetani cause disease?
they produce a powerful neurotoxin called tetanospasmin
51
What does tetanus do?
Blocks inhibitory nerve impulses
52
Is tetanus a problem today?
In developing countries it is very deadly but in developed countries it is very rare due to vaccination
53
What are symptoms of tetanus?
Increased muscle tone and painful spasms Trismus (lockjaw) Risus sardonicus Abdominal rigidity Apnoea Autonomic NS instability Sweating cardiac arrhythmias labile BP high fatality
54
What does clostridium botulinum do?
produces neurotoxin that causes paralysis preventing release of acetylcholine at neuromuscular junction causing progressive descending paralysis
55
How does clostridium botulinum enter the body?
enters in food or wound contamination
56
What food can potentially contain clostridium botulinum?
aged or preserved foods
57
Where can clostridium difficile found?
In faeces of 30% of hospital patients Spores persist in environment and spread on hands of staff
58
What kind of toxin can clostridium difficile produce and what type of disease does it cause?
It produces enterotoxins and antibiotic associated diarrhoea (during or after antibiotic treatment) This is due to death of competitive microbiota
59
How severe is the diarrhoea associated with clostridium difficile?
Mild to severe and intractable
60
What does clostridium difficile associated diarrhoea cause in its most severe cases?
Pseudomembranous colitis which is a severe inflammatory condition
61
What are lactobacillus like in terms of oxygen use and endospore formation?
Lactobacillus can be aerobic or anaerobic and are regular non-endospore producing bacteria
62
What is the normal role of lactobacillus species?
They are part of the normal flora of the GIT and vagina. They ferment carbohydrates to lactic acid and maintain vaginal pH at 3.8 - 4.5
63
What is the oxygen usage and endospore formation of listeria like?
They are aerobic and non-endospore forming
64
Where can listeria be found?
Water Animal and human faeces Raw meat Dairy products Vegetables
65
What temperature can listeria grow at that is clinically significant?
4 degrees
66
What are some high risk foods associated with listeria?
coleslaw, raw cabbage Unpasteurised milk Soft cheeses Pate Undercooked chicken Prepacked sliced meals
67
Is listeria infection common?
no but causes serious infections
68
Who typically has issues with listeria and who doesn't?
It creates no symptoms in people with normal individuals. Elderly, infants, immunocompromised, and pregnant people typically have issues with listeriosis. Fetal infection can occur if mother is infected.
69
What are the symptoms of listeriosis?
Non-specific bacteraemia - flu like symptoms Septicaemia +/- meningitis
70
What does infection of listeria do to pregnant people?
miscarriage, stillbirth, prem labour Live birth - septicaemia, meningitis, and neurological damage
71
What is the oxygen usage and endospore formation like in erysipelothrix rhusiopathiae?
It is aerobic and non-endospore forming
72
How does erysipelothrix enter the body?
Through skin abrasions caused by handling meat, poultry, fish, crustaceans, and farm animals
73
What does infection of erysipelothrix look like?
Painful, raised areas of inflammation of the skin
74
What can be said about corynebacterium's oxygen usage and endospore formation and morphology?
They are aerobic and non-endospore forming. They are irregular with what is described as coryneform or diptheroid morphology
75
Where are corynebacterium found?
Many are commensals of humans and animals
76
Are corynebacterium common infections?
No they are often associated with other things like foreign devices
77
What is the major pathogen of the corynebacterium genus?
Corynebacterium diphtheriae
78
What disease is caused by corynebacterium diphetheriae?
diphtheria
79
What demographic is typically affected by diphtheria?
Children without vaccinations
80
What happens during diphtheria?
Exotoxin produced which infects nose and throat which ulcerate and swell. The swelling can cause asphyxiation.
81
What are the symptoms of diphtheria?
Skin ulcers Inflammation, swelling and pseudomembrane formation in nasopharynx and upper airways
82
What happens when the exotoxin produced by corynebacterium diphtheria is absorbed into the body?
A severe pathology causing: Myocarditis (damage to heart muscle) arrhythmias and heart failure Neuropathy with paralysis of palate muscles and cranial nerves as well as peripheral sensory and motor neuropathy. Other sites of damage include focal necrosis in the kidneys, adrenals, and liver
83
When was the first diphtheria vaccine introduced?
1932
84
What is the oxygen usage and spore formation of propionibacterium like?
Anaerobes that do not produce spores
85
What is propionibacterium morphology like?
irregular coryneform morphology
86
Where are propionibacterium typically found?
Commensals on human skin and they are non pathogenic which typically contaminate blood cultures and P.acnes have a role in acne vulgaris
87
Where can propionibacterium cause infections?
Implanted foreign devices
88
What are some aerobic nonendospore forming actinomycetes?
Nocardia Actinomadura Streptomyces
89
What are actinomycetes?
filamentous and branching structure
90
What is aerobic capacity of actinomycetes?
Can be both aerobic and anaerobic
91
Where are actinomycetes typically found?
Soil and rotting vegetation
92
What do actinomycetes look like on agar plates?
like fungi
93
What are some diseases caused by actinomycetes?
Actinomycotic mycetomas which look like eumycotic mycetoma Other nocardia infections Actinomycosis
94
What are the most common actinomycotic genera that cause disease?
Nocardia Actinomadura Streptomyces
95
How do actinomyces enter the skin?
Through cutaneous implantation such as through a stick, thorn, or splinter
96
What kind of infection do actinomyces cause?
Chronic lesion that takes years to develop resulting in swelling, dischargind sinuses and granules
97
Where is nocardia typically seen?
Immunocompromised hosts
98
How does nocardia cause infection?
it enters through inhalation as a respiratory infection and forms nodules in the lungs as well as pneumonia and cavities. It abscesses in organs
99
How does nocardia spread?
Through blood
100
What does nocardia do in immunocompetent patients?
Skin implantation Nodular/pus-filled lesions tracking up lymphatics Very similar to fungal infection called "sporotrichoid"
101
Where are actinomyces species typically found?
Commensal bacteria of oropharynx, GIT, and genital tract
102
What are the forms of actinomycete disease?
Cervicofacial Thoracic Abdomen, pelvis (associated with long standing intrauterine devices)
103
What are the symptoms of cervicofacial actinomycosis?
Swelling Contiguous spread Discharging fistulas Pus containing granules

IMED2001 UWA (44 decks)

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