Gram Positive Bacteria - Lecture 5 Flashcards Preview

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Flashcards in Gram Positive Bacteria - Lecture 5 Deck (131):
1

What are streptococcus sp. characteristics? (Morphology)

These bacteria are gram positive COCCI bacteria that are organized in chains (~2-6/chain)

2

How are streptococcus bacteria clasified?

These are classified based on their hemolytic activity. Classified as alpha, beta or gamma.

Beta-hemolytic bacteria are further classified based on Lancefield groupings (A-U), which is their cell wall carbohydrate antigen.

3

What are the four streptococcus human pathogens?

1) Streptococcus pneumoniae
2) Streptococcus pyogenes
3) Streptococcus agalactiae
4) Streptococcus mutans

4

Describe alpha-hemolytic bacteria.
What colour does it appear on a blood agar where the colonies grow?
Give an example.

Partial hemolysis
Appears green in colour
S. pneumoniae

5

Describe beta-hemolytic bacteria.
What colour does it appear on a blood agar where the colonies grow?
Which further classes are the most pathogenic?
Give an example.

Complete hemolysis
Appears as a full clearing on and around where the colonies grow
Lancefield groups A and B are the most pathogenic
S. pyogenes (group A) and S. agalactiae (group B)

6

Describe gamma-hemolytic bacteria.
What colour does it appear on a blood agar where the colonies grow?
Give an example.

No hemolysis
No clearing
Enterococcus faecalis

7

What is another name for streptococcus pneumoniae?

Pneumococcus

8

Describe pneumococcus: morphology, encapsulated or acapsular, bile sensitivity or not?

Diplococci
Encapsulated
Bile sensitivity

9

What are two features of a pneumococcus infection?

Bacterial pneumonia
Bacterial meningitis

10

What bacterial infection is described as:
Fever, malaise, cough, pleuritic chest pain
Purulent or bloody sputum
Otitis media (inflammation of the inner ear)

Bacterial pneumonia

11

What bacterial infection is described as:
Stiff neck, headache, fever (characteristic triad)

Bacterial meningitis
(streptococcus pneumoniae is the most common cause of meningitis in children)

12

How is streptococcus pneumoniae transmitted and how long is the typical incubation period?

Transmitted via respiratory droplets
Incubation period is 1-3 days

13

What are treatment strategies for streptococcus pneumoniae?

Vaccine preventable
Broad-spectrum antibiotic resistance tests

14

What else is Streptococcus pyogenes known as?

Group A Streptococcus (GAS)

15

GAS is CAMP-tes negative, meaning what?

CAMP-factor does NOT increases hemolytic activity (unlike beta-hemolytic S. aureus)

16

What are clinical features of GAS?

Pharyngitis/Tonsilitis - aka "strep throat"
Scarlet fever
Infections of the skin

17

Describe pharyngitis/tonsilitis (strep thoat)

Inflammation of the pharynx/tonsils
Fever, malaise, sore throat

18

Describe scarlet fever

Occurs in patients with strep throat (usually children)
Erysypelas (rash), typically on the face, "strawberry tongue"

19

What are four infections of the skin caused by GAS? (give brief descriptors)

1) Impetigo - superficial, common in children, contact sport

2) Cellulitis - subcutaneous, inflammation of the skin and dermal layers

3) Folliculitis - inflammation of the hair follicles

4) Necrotizing fasciitis - aka flesh-eating disease

20

What are some potential complications of GAS infections? (3)

Acute rheumatic fever
Acute glomerulonephritis
Infective cardiopathies

21

What complication of GAS infection is described as:
Polyarthritis, carditis, rheumatic heart disease
May occur weeks following GAS infectoin

Acute rheumatic fever

22

Which complication of GAS infection could lead to an autoimmune disease - antibody cross-reactivity against joints and myocardium (type II hypersensitivity)

Acute rheumatic fever

23

What complication of GAS infection involves inflammation of the glomeruli (kidney) and may occur weeks following the GAS infection of the URT or skin

Acute glomerulonephritis

24

What is the most common infective cardiopathies (a complication of a GAS infection)

Endocarditis most common

25

How are GAS infections transmitted and how long is the typical incubation period?

Transmitted via respiratory droplets
Incubation period - 1-5 days

26

What are treatment strategies of GAS infections?

Penicillin and related antibiotics, cephalosporins

27

What else is streptococcus agalactiae known as?

Group B streptococcus (GBS)

28

Are GBS CAMP-test positive or negative? meaning what?
Encapsulated or acapsular?

CAMP-test positive - meaning CAMP-factor increases hemolytic activity
Encapsulated

29

What are clinical features of GBS? Briefly describe. (5)

1) Symptomatic in newborns, elderly, immunocompromised, risk of maternal transmission

2) Newborn pneumonia - fever, myalgia, fatigue, consolidation of the lung, chest pain

3) Meningitis (neonatal) - fever, headache, neck stiffness

4) Sepsis - leading cause of neonatal sepsis

5) UTI - less common

30

How are GBS infections transmitted?
How long is the typical incubation period of GBS?

Transmitted via respiratory droplets
Incubation period 5-7 days

31

What are treatment strategies of GBS infections?

Penicillin and other bata-lactams

32

What does viridans streptococcui include?

Includes streptococci mutans and other commensals of the mouth

33

Are viridans streptococci optichin-sensitive or nonsensitive, encapsulated or acapsular?

Optihin-sensitive
Acapsular

34

These clinical features are characteristic of which bacterial infection?

1) Symptomatic in newborns, elderly, immunocompromised, risk of maternal transmission

2) Newborn pneumonia - fever, myalgia, fatigue, consolidation of the lung, chest pain

3) Meningitis (neonatal) - fever, headache, neck stiffness

4) Sepsis - leading cause of neonatal sepsis

5) UTI - less common

GBS clinical features

35

These clinical features are characteristic of which bacterial infection?

1) Impetigo - superficial, common in children, contact sport

2) Cellulitis - subcutaneous, inflammation of the skin and dermal layers

3) Folliculitis - inflammation of the hair follicles

4) Necrotizing fasciitis - aka flesh-eating disease

GAS clinical features

36

These clinical features are characteristic of which bacterial infection?

1) Plaque, tooth decay, cavities
2) infective cardiopathies - subacute infective carditis

Viridans streptococci

37

Wha are the assoiciated risk factors of cardiopathies? and describe presentation.

Risk factors: congenital heart defects/valvular defect, artificial heart valves, diabetes, dental surgery.

Presentation: slowly progressing, low grade to no fever, chest pain and sepsis

38

What are clinical features of viridans streptococci? (2)

1) Plaque, tooth decay, cavities
2) infective cardiopathies - subacute infective carditis

39

What is the incubation period of viridans streptococci?

variable incubation period

40

What are the treatment strategies for viridans streptococci?

Brushing and antiseptic mouthwash, antibiotics for sepsis and cardiopathy

41

What are the characteristics of Staphylococcus?

Gram positive cocci
Organized in grape-like clusters
Catalase-positive, facultative anaerobes

42

What are human pathogens of Staphylococcus? (3)

1) Staphylococcus aureus - skin infection, bacterial pneumonia, bacterial meningitis

2) Staphylococcus epidermidis - sepsis (IV catheters and medical prostheses

3) Staphylococcus saprophyticus - UTIs, cystitis

43

Give three characteristics of Staphylococcus aureus

1) Opportunistic pathogen - resident on skin
2) Characteristic golden colonies ("aura" = golden)
3) Identification - morphology, coagulase (+)

44

What are some diseases caused by Staphylococcus aureus? (7)

1) Skin infections - impetigo, abscess, cellulitis, scalded skin syndrome
2) Sepsis/Septic shock
3) Bacterial pneumonia
4) Bacterial meningitis
5) Mastitis
6) Infective cardiopathy
7) Food poisoning

45

These diseases can all be caused by which bacterial infection?

1) Skin infections - impetigo, abscess, cellulitis, scalded skin syndrome
2) Sepsis/Septic shock
3) Bacterial pneumonia
4) Bacterial meningitis
5) Mastitis
6) Infective cardiopathy
7) Food poisoning

Staphylococcus aureus infection can cause these diseases

46

What is described as a collection of pus in a tissue associated with inflammation?

An abscess

47

What is described as blisters and sores (pustulous or not), found commonly on the face/neck?

Impetigo

48

What is described as an inflammation of connective tissue in the dermal, subcutaneous layers of the skin?

Cellulitis

49

What is described as pain and redness of the skin, blisters and desquamation?

Scalded skin syndrome

50

Describe staphylococcal bacterial pneumonia (caused by staphylococcus aureus)

How would it be treated?

Commonly nosocomial, secondary pneumonia
Fever, chest pain, coughing, difficulty breathing
Patchy areas of consolidation in the lung
Rapidly progressive

Treat with antibiotics, steroids

51

Describe Sepsis

Septic inflammatory response, spread to various organs
Multiple presentations, organ effects, may lead to secondary infection even following clearance from the blood

52

What percentage of bacterial meningitis is due to staphylococcal aureus?

1-10% of meningitis

53

What is meningitis?
What does it cause/symptoms?

Inflammation of the meninges in the brain causing cognitive impairment and fever

54

Describe acute infective endocarditis:
What is it, and what are the symptoms?

Inflammation of the endocardium
Sudden onset of fever, new/changing heart murmer, chest pain, Osler's nodes and Janeway lesions on the hands and feet

55

What bacterial infection can cause mastitis?

Describe mastitis

Common treatments

Caused by Staphylococcus aureus

Infection of the breast tissue
Abrasions and skin breaks during breastfeeding common, risk of sepsis and ineffective cardiopathy
Very common in cattle

Common treatments: antibiotics, surgery

56

Describe food poisoning as caused by Staphylococcus aureus

Source

Mishandled meat, poultry, eggs, dairy
Salt-stable (cured foods)
Mostly due to toxin production (heat-stable)
produce enterotoxins A-E
Do not reheat food that has been at room temperature for more than 2hrs
Causes severe vomiting 2-4hrs after infection

57

What are drug-resistant staphylococcus aureus?
Caused by what?

Methicillin- and vancomycin-resistant Staphylococcus aureus (MRSA & VRSA)

Caused by antibiotic overuse, misuse, and patient non-compliance

Nosocomial

58

What are treatment strategies for MRSA and VRSA?

Incision, drainage or surgery of affected area
1st and 2nd generation glycopeptide antibiotics - inhibit bacterial cell wall and RNA synthesis
Streptogramins - inhibit bacterial ribosome

59

staphylococcus aureus caused epidermidis is commensal of the skin. is it
Coagulase positive or negative?
Hemolytic or non-hemolytic
Encapsulated or acapsular?

Coagulase negative
Non-hemolytic
Encapsulated

60

Septicemia is caused by an opportunistic infection transmitted from what (typically)?

Medical devices - catheters, shunts, prostheses etc.
Biofilm formations on devices is a major virulence factor due to adhesion molecules and ability to bind to plastic device

61

What are some clinical features of staphylococcus aureus epidermidis?

Depends on site of infection
UTI - pain or difficulty urinating
Subacute infective endocarditis

62

What are treatment strategies for staphylococcus aureus epidermidis?

vancomycin and related, although antibiotic resistance is common

63

Staphylococcus saprophyticus
Coagulase positive or negative?
Drug resistant? to what?
Encapsulated or acapsular?

Coagulase negative
Novobiocin resistant
Some capsulated, some acapsular strains

64

Treatment for Staphylococcus saprophyticus

Treat with Quinolones - inhibit DNA replication and trimethoprim - folic acid and metabolism inhibitor

65

Give characteristics of Bacillus sp.

Gram - or +

Catalase - or +

Size

Oxygen tolerance

Spore-forming or not

Gram (+) rods, catalase (+)

Relatively large bacteria (35um long)

Aerobic or facultatively anaerobic

Sporeforming

66

Give four important species of Bacillus

1) Bacillus subtilus

2) Bacillus cereus

3) Bacillus anthracis

4) Bacillus thurigiensis

67

Describe the characteristics of endospores including structure, conditions of formation, content

Dormant, hearty, nonreproductive structure

Formed ‘from within’, during conditions of stress

Genetic material, some cytoplasm, tough exterior

‘Cryptobiotic’

68

What makes endospores particularly hearty

Resist heat, freezing,
dessication

Resist acidity, chemical disinfectants, irradiation

Commonly found in soil and water

Survive long periods of time (millions of years)

Endospores can survive unfavourable conditions for extremely long periods of time

Conditions that favour vegetation lead to germination of spores (sufficient nutrients, oxygen, moisture, etc.)

69

Other than Bacillus, what are some other spore forming bacteria?

Clostridium sp. cyanobacteria

70

Saporophytes a classification of bacillus
How do they obtain nutrients?
Where do they live?

Obtain nutrients from dead organic matter

Saprophytic bacteria live mostly in soil/water

71

Give three Saprophyte human pathogens

1) Bacillus subtilus - food poisoning

2) Bacillus cereus – food poisoning, mastitis, skin infections

3) Bacillus anthracis – anthrax
diseases

72

What are some saprophyte probiotics? (3)

1) Lactobacillus sp.
2) B. subtilis
3) B. cereus

73

What is a saprophyte insect pathogen?

Bacillus thuringiensis

74

This bacteria is a saprophyte and member of the resident gut flora. It is motile (flagellate) and may appear in groups or chains. What is it?

B. subtilus

75

Pathogenic B. subtilus can cause ___1___
It is ___2___ in early phase and ___3___ in late phase
4) How long does it take to resolve and 5) how long is the incubation period?

1) food poisoning - rare
2) Emetic
3) Diarrheal
4) 24-48hrs
5) Short incubation - hours

76

What are virulence factors of B. subtilus?

Sibtilisin - serine endopeptidase
Catalase - metabolize H2O2

77

This bacteria is a saprophyte and a member of the resident gut flora. It is motile (flagellate), appears in groups or chains and is β-haemolytic. What is it?

B. cereus

78

What are four clinical presentations of pathogenic B. cereus?

1) Food poisoning (2-5%) - diarrheal (long incubation), Emetic (short incubation)
2) Mastitis
3) Skin infection
4) Diseases associated with the sepsis in immunocompromised patients

79

This bacteria is a saprophyte, nonmotile (aflagellate) and chainforming. It is an etiological agent of anthrax diseases and was discovered by Robert Koch in 1877. What is it?

B. anthracis

80

What are Koch's four postulates?

1. The microorganism must be found in abundance in all organisms suffering from the disease, but should not be found in healthy organisms.

2. The microorganism must be isolated from a diseased organism and grown in pure culture.

3. The cultured microorganism should cause disease when introduced into a
healthy organism.

4. The microorganism must be reisolated from the inoculated, diseased experimental host and identified as being identical to the original specific
causative agent.

81

What are the three classifications of B. anthracis?
Which is most fatal, very rare?
Causes?

1) Pulmonary anthrax - most fatal
- Caused by inhalation of spores (not contagious)

2) Cutaneous anthrax
- Introduction of spores through breaches in the skin

3) Intestinal anthrax - very rare
- Ingestion, symptoms of food poisoning

82

Describe the Early stages of pulmonary anthrax

Fever, coughing, sore throat, fatigue, sweating, vomiting, diarrhea, headache, nausea, chest pain, and shortness of breath

83

Describe the late stages of pulmonary anthrax

High fever, chest pain, hemorrhagic pathology, death within 48 hours

84

Describe the appearance of cutaneous anthrax

Lesions with black necrotic center

85

What could Septicemia following an infection of anthrax lead to?

Meningitis

86

What are virulence factors of B. anthracis?

Anthrax lethal toxin – degrades host signalling
pathway components, leading to cell death

Anthrax edema toxin – causes accumulation of fluid in tissue

87

What are the incubation periods of B. anthracis infections?
1) pulmonary
2) Cutaneous
3) GI

1) 1-7 days
2) 1-2 days
3) 1-7 days

88

What are treatments for B. anthracis?

Vaccine limited availability (military personnel)

Early tx very key – 60 day regimen of ciproflaxin (quinolone) or doxycycline (tetracycline)

89

Give characteristics of Clostridium sp.

Gram - or +

Morphology

Oxygen tolerance

Spore-forming or not

Gram positive

Rods

Anaerobic (mostly obligate anaerobic)

Endospore forming

90

What are four Clostridium human pathogens?

1) Clostridium tetani

2) Clostridium botulinum

3) Clostridium perfringens

4) Clostridium difficile

91

What do free radicals/reactive oxygen species (ROS) do? (4)

1) Modify proteins
2) Regulate the function of proteins
3) Damage nucleic acid
4) Cause cell death

92

What antioxidant defenses to some bacteria posses? (3)

1) Superoxide dismutase
2) Peroxidase
3) Catalase

93

What are four diseases caused by Clostridium sp.?

1) C. tetani - Tetanus

2) C. botulinum - Botulism, Floppy baby syndrome, Wound infection

3) C. perfringens - Gastroenteritis, Gas gangrene

4) C. difficile - Antibiotic-associated diarrhea

94

Describe C. tetani
Oxygen tolerance
Motility

Appear as 'tennis rackets' under microscope examination
Obligate anaerobe
Motile

95

Describe generalized tetanus and what it may lead to

Prolonged contraction of skeletal muscle fibers

Characteristic opisthotonus
–Severe hyperextension and spasticity of head, neck, and spine
–Spasm of axial muscles of the spinal column leads to characteristic arching

May lead to respiratory failure

Hypertension, tachycardia

96

How is C. tetani transmitted?

What is its incubation period?

Transmitted via infected wounds

Incubation period usually 1 wk, but could be several months

97

How is neonatal tetanus infection transmitted?

Infection through umbilical stump

98

Describe localized tetanus

Spasms are isolated to the site of injury
Self-resolving

99

What classifies cephalic tetanus?

CNS involvement - rare

100

What is the treatment for C. tetani?

Vaccine (tetanus shot) = toxoid vaccine

Childhood vaccine with booster recommended every 10 years

Administered following severe trauma to the skin (postexposure prophylaxis)

101

What is C. botulinum oxygen tolerance?

Obligate anaerobe - expresses superoxide dismutase

102

How is food-borne botulism transmitted? (What are risk factors)

Ingestion of spores from improperly canned foods
Sporulation may occur at higher pH

103

What are symptoms of botulism?

Flaccid muscle paralysis - slurred speech, droopy eyelids, difficulty swallowing, generalized muscle weakness

104

Botulinum toxin is a neurotoxin with multiple serotypes. Which serotypes cause human disease and how does the toxin act?

Serotypes A-G exist, with A, B, E & F causing human disease.

Toxin acts by blocking the release of acetylcholine from motor nerve endings

105

How is infant botulism transmitted?
("floppy baby syndrome")

Food-borne
Honey - spores found in honey can germinate in the less acidic gut of newborns

106

What is wound botulism?

Infection of wound with spores

107

What are treatments for C. botulinum?

Antitoxin - antibody against botulinum toxin
Ventilator for respiratory complications
No vaccine available

108

What are commercial uses for C. botulinum?

Muscle pain disorders
Hyperhydrosis
Botox - cosmetic

109

Compare direct vs indirect pathology

Direct pathology comes from the effect of the pathogen of a cell, tissue or organ
-Viral replication and lysis in a tissue causes damage to that tissue
-Bacterial toxins may cause local or distal effects - tetanospasmin and botulinum toxin exert their effect in the CNS even though the bacteria don't replicate in the CNS


Indirect pathology comes from secondary effects and immune pathology
-Cell damage mediated by inflammatory mediators at a site of replication
-Symptoms associated with tissue remodeling following damage

110

Which bacteria is non-motile and double-zone heamolysis?

C. perfringens

111

Describe the effects of Clostridium perfringens enterotoxin (CPE)

Tissue necrosis
Destroys tight junctions between endothelial cells in the gut

112

What are symptoms of C. perfringens

Diarrhea, vomiting, abdominal cramping, fever
Clostridial necrotizing enteritis (rare, fatal)

113

How long is the incubation period for C. perfringens?

8-24 hours

114

Gas gangrene is a serotype of C. perfringens, which one? and what is it also known as?

How is it transmitted?

Serotype A
aka clostridial myonecrosis

Transmitted by infection at a site of trauma, usually lacking blood supply - contaminated surgical equipment, gloves et.

115

What are the symptoms of gas gangrene?

what is its incubation period?

Muscle wasting
Edematous, necrotic blisters
Putrefcation of tissue with smell

Incubation period 1-4 days

116

What are the virulence factors of C. perfringens?

α-toxin – destroys tissue and produces gas

β, ε, ι toxins – increase vascular permeability

δ, φ toxins – haemolysins

117

What are treatments for C. perfringens?

Amputation
Penicillin, clindamycin, rifampicin, metronidazole

118

Describe C. difficile:
Motility?
Oxygen tolerance?
Opportunistic?

Motile
Obligate anaerobe
Opportunistic pathogen

119

Describe antibiotic resistant diarrhea (c. difficile)

occurs as a consequence of antibiotic useage
Fever, diarrhea, vomiting, abdominal pain, crampin

120

Describe pseudomembranous colitis (c. difficile)

Inflammation of the colon
Pseudomembrane formation in the colon
Abdominal pain with rebound tenderness

121

What are treatments for c. difficile?

What is the recurrence rate

Halting current antibiotics
Vancomycin, metronidazole
Recurrence rate is extremely high

122

How is c. difficile transmitted and how can it be prevented?

Transmitted fecal-oral
Prevented via hygiene!!

123

This bacteria is gram positive and polymorphic.
It's toxin inhibits translational machinery.
What is it?

Corynebacterium diptheria (diptheria)

124

What are clinical features of diptheria?

Sore throat, low fever, dark pseudomembrane on the tonsils, pharynx, and/or nasal cavity

Fever, chills, fatigue, sore throat, hoarseness, cough, headache, painful swallowing, difficulty breathing

Skin lesions also common

125

What are complications of diptheria?

Cardiac and nervous system complications

126

How is diptheria transmitted and what is its incubation period?

Transmitted through contact, respiratory droplets and contaminated food

Incubation period 2-5 days

127

What are treatments for diptheria?

Toxoid vaccine available (pentavalent or DPT)

Responsive to multiple antibiotics

Severe cases treated with diptheria
antitoxin

128

Describe characteristics of Listeria monocytogenes (lysteriosis)
Gram positive/negative?
Morphology
Food- air- water-borne?
Oxygen tolerance?
Motility?
Psychrotrophic?
Reproduction?
Hemolysis?
Catalase positive/negative>

Gram positive
Rod-shaped
Food-born pathogen
Facultative anaerobe
Motile
Psychrotrophic (survive cold temps)
May reproduce extracellularly or intracellularly in macrophages
Beta-hemolytic
Catalase positive

129

What are clinical presentations of Listeriosis?

Diarrhea, fever, muscle aches
CNS involvement
20-30% fatality rate in infected patients

130

How is listeriosis transmitted and how long is its incubation period?

Transmitted through ingestion of contaminated food (processed or fresh)

incubation period is 1-70 days (typically 2-3 wks)

131

What are treatments for listeriosis?

Ampicillin or other antibiotics