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Year 3 > Microbiology > Flashcards

Microbiology Flashcards

1
Q

Describe the characteristics of Gram positive bacteria, and give examples.

A

Stain purple with gram stain.
Simpler cell wall than gram negative, but a thicker peptidoglycan layer.

2 main cell wall layers- peptidoglycan (with lipotechoic acid and techoic acid), and then an inner/cytoplasmic membrane.

Are less resistant to antibiotics.

Examples: streptococcus, staphylococcus, Bacillus, Chlostridium, Listeria

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2
Q

Describe the characteristics of Gram negative bacteria, and give examples.

A

Stain pink with gram stain.
More complex cell wall: lipopolysaccharide, then an outer phospholipid membrane, petidoglycan then inner membrance.

More resistant to antibiotics.

Outer membrane with LPS- lipid portion is toxic and can cause fever and shock.

Examples: E.coli, Neisseria gonorrhoeae, cyanobacteria, proteobacteria, helicobacter.

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3
Q

Where are lactobacilli normally found in the body?

A

Vagina

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4
Q

Where are candida albicans normally found in the body?

A

Vagina, mouth, skin

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5
Q

How are streptococcus bacteria arranged?

A

In a chain of cocci (spheres)

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6
Q

How are staphylococcus bacteria arranged?

A

In a bunch of cocci (spheres)

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7
Q

What are the 4 main components of bacteria which antibiotics target?

A
  1. Cell wall- Beta lactams (Penicillins, Cephalosporins and Carbapenems) and Glycopeptides (Vancomycin and Teicoplanin)
  2. Protein synthesis (Tetracyclines eg, Doxycycline, Aminoglycosides eg Gentamycin, Macrolides eg. Erythromycin and Streptogramins eg. Pristamycin)
  3. Folate synthesis (Trimethoprim or Sulfonamides eg. Sulfadiazine)
  4. DNA synthesis - Quinolones (Ciprofloxacin) or Metronidazole
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8
Q

How do Beta lactam antibiotics work? Give examples. What are their common significant side effects?

A

Beta lactams include Penicillins eg, Amoxicillin, Cephalosporins eg. Cephalexin, and Carbapenems eg. Imipenem.

Bind transpeptidases, preventing peptidoglycan cross-linkage.

Side effects include hyposensitivity, CNS toxicity and seizures, and increased risk of GI disturbances and C. Difficile.

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9
Q

How do Glycopeptides work? Give examples. What are their common significant side effects?

A

Glycopeptides (eg. Vancomycin and Teicoplanin) work by binding peptides in peptidoglycan, to inhibit cross-linking.

Side effects include Nephrotoxicity and Red man syndrome (an infusion related hypersensitivity reaction)

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10
Q

How do Tetracyclines work? Give examples. What are their common significant side effects?

A

Tetracyclins (eg. Doxycycline) work by inhibiting bacterial protein synthesis, by binding to the 30S ribosome subunit.

Side effects include Binding to teeth and causing staining.

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11
Q

How do Aminoglycosides work?Give examples. What are their common significant side effects?

A

eg Gentamycin.
Prevent bacterial protein synthesis, by binding the 30S ribosome subunit.

Side effects include being nephrotoxic and ototoxic.

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12
Q

How do Quinolones work? Give examples.

A

Quinolones include Ciprofloxacin and Moxifloxacin.

They work by inhibiting bacterial DNA synthesis, by inhibiting bacterial DNA gyrase.

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13
Q

Describe the process of gram staining.

A
  1. Add Crystal violet.
  2. Fix with iodine.
  3. Wash with acetone.
  4. Counterstain with neutral red.
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14
Q

How do Sulfonamide antibiotics work? give examples of side effects.

A

Inhibit folate synthesis, by preventing addition of para-amino benzoic acid to folic acid.

Side effects include Steven-Johnson syndrome, skin rash.

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15
Q

Give examples of Gram positive bacteria.

A

Bacilli- Aerobic = Listeria, Bacillus
Anaerobic= C.diff

Cocci- Staph eg. S.aureus, S.epidermidis
Strep- S.pneumoniae, S.pyogenes

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16
Q

Give examples of Gram negative bacteria

A

Diplococci: Neisseria meningitidis, N. Gonorrhoea
Coccobacilli: Haem influenzae, Brucella, B.pertussis
Bacilli: Shigella, Salmonella, E.coli, Pseudomonas, Klebsiella, Enterobacter

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17
Q

Name some infections of the skin epidermis.

A

Impetigo
Folliculitis
Furunculosis

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18
Q

Name 2 infections of the skin dermis.

A

Carbunculosis

Erysipelas (rare)

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19
Q

Name 2 infections of the subcuntaneus layer of skin.

A

Cellulitis

Necrotising fascitis

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20
Q

What is impetigo?

A

Infection of epidermis
More common in children
Golden crusts on erythematous skin

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21
Q

What is folliculitis?

A

Infected hair follicle- often the scalp and groin.

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22
Q

How is folliculitis treated?

A

Flucloxacillin

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23
Q

What is furunculosis?

A

Deep inflammation due to folliculitis

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24
Q

What is a carbuncle?

A

Boil in the dermis, extending into subcutaneous layer

Abscess forms

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25
Q

What is cellulitis and where does it appear?

A 
Inflammation of dermis/ subcutaneous layer
Often lower limbs, unilateral
Red, hot, swollen, painful
No necrosis
May be red halo around a joint
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26
Q

How is cellulitis treated?

A

Penicillin V AND Flucloxacillin

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27
Q

Which bacteria usually causes cellulitis?

A

S. Aurues

Occaisionally S. pyogenes

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28
Q

What results may be found on a blood test of a patient with cellulitis?

A

Raised WCC and CRP

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29
Q

What is erysipelas and where might it be found?

A

Rare
Infection of dermis/subcutaneous layer or face/legs
Clear border, raised orange peel appearance

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30
Q

Which Bacteria usually causes Erysipelas?

A

Group A Strep

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31
Q

How is Erysipelas treated?

A

Penicillin

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32
Q

What are the 3 stages of necrotising fascitis?

A
  1. Acute- trauma and pain disproportionate to injury. Flu like symptoms
  2. Advanced- purple swelling
  3. Critical- toxic shock, drop in BP, unconscious
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33
Q

Which bacteria usually cause necrotising fascitis?

A

Group A Strep

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34
Q

Which bacteria causes gas gangrene?

A

Chlostridium perfringens

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35
Q

Which bacteria usually cause Septic arthritis?

A

S. aureus
Strep
N. Gonorrhoea
Gram negative bacilli

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36
Q

What are the risk factors for septic arthritis?

A

Joint disease
Immunosuppression
Recent joint surgery
Diabetes, CKD

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37
Q

Which joint is most commonly affected by septic arthritis?

A

Knee

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38
Q

How is septic arthritis treated?

A

IV Flucloxacillin

May need debridement

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39
Q

What is osteomyelitis?

A

Bone infection

Often in long bones of legs, arms or back

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40
Q

How is osteomyelitis treated?

A

Flucloxacillin

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41
Q

What is a dermatophyte infection?

A

Fungal infection of skin also known as tinea

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42
Q

How are dermatophyte infections treated?

A

Antifungals eg. Nystatin, Canestan

If drug resistant or invasive use Fluconazole

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43
Q

What are the 2 most common causes of soft tissue infections?

A

S. Aureus

S. Pyogenes

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44
Q

Treponema pallidum causes which STI?

A

Syphillis

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45
Q

What type of bacteria is Gonorrhoea?

A

Gram neg diplococci

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46
Q

How is a gonorrhoea infection treated?

A

Penicillin

If allergic: Cephalosporin or Ciprofloxacin

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47
Q

What type of bacteria is Chlamydia?

A

Gram negative
Obligate intracellular so cant grow on culture media

Has elementary body and reticulate body

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48
Q

How is chlamydia treated?

A

Tetracyclines eg. Doxycycline

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49
Q

What type of organism is Trichomonas vaginalis?

A

Protozoa with flagella

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50
Q

How is Trichomonas vaginalis treated?

A

Metronidazole

51
Q

What type of organism is Candida albicans and how is it treated?

A

Yeast

Fluconazole

52
Q

What is a chancre?

A

Syphilis sore
Firm painless not itchy

Disappears after 4 weeks but bacteria remain

53
Q

Which organisms most commonly cause a UTI?

A

E coli

Pseudomonas aeruginosa in complicated patients

54
Q

Proteus mirabilis is often associated with __________

A

Kidney stones

55
Q

Which antibiotics are recommended for UTIs?

A

NItrofurantoin (has low resistance risk) BD for 3 days

Trimethoprim BD for 3 days

56
Q

Which antibiotics are recommended for acute pyelonephritis?

A

Cefalexin (Cephalosporin)

Co-Amoxiclav

57
Q

What is diagnostic of a UTI?

A

Pyuria

>10^% CFU/ml

58
Q

What type of virus is Hep A and how is it spread?

A

ssRNA

Faeco oral, contaminated food and water and shellfish

59
Q

Where Hep A virus is endemic how is it spread?

A

Person to person contact

Usually younger patients (asymptomatic)

60
Q

How can Hep A be diagnosed on blood test?

A

HAV IgM raised from day 25
HAV IgG raised for life

AST and ALT raised

61
Q

What are the risk factors for Hep A?

A

Travel
MSM
IVDU

62
Q

Which types of Hepatitis are vaccines available for?

A 
Hep A
Hep B (indirectly Hep D)
63
Q

How is Hep B spread?

A 
Blood
IVDU
Sex
Direct conact
Vertical transmission
64
Q

Where Hep B is endemic it leads to ___________ infection.

A

Chronic

65
Q

Where Hep B is sporadic it leads to ____________ infection.

A

Acute

66
Q

How can Hep B be diagnosed on a blood test?

A 
HbsAg (Hep B surface antigen)
HbeAg (Hep B e antigen- determines infectivity)
Anti Hbs
Anti Hbe
IgM (acute)
IgG (chronic)

Raised LFTs

67
Q

Hep B infection can lead to ___________

A

Cirrhosis

Hepatocellular carcinoma

68
Q

What will be the blood results in ACUTE Hep B infection?

A

Raised LFTs
HbsAg positive
HbeAg positive

Anti Hbe may be present
IgM and IgG

69
Q

What will be the blood results in PAST Hep B infection?

A

Normal LFTs
HbsAg positive
HbeAg may be positive

Anti Hbs
IgG

70
Q

What type of virus is Hep B?

A

dsDNA enveloped

71
Q

Which Hepatitis viruses are ssRNA viruses?

A

Hep A
Hep C
Hep D
Hep E

72
Q

Which Hepatitis viruses have envelopes?

A

Hep B
Hep C
Hep D (uses Hep B)

73
Q

How can Hep B be treated?

A

Interferons

Lamivudine

74
Q

What type of vaccine is the Hep B vaccine?

A

Recombinant

Booster needed every 5 years
Aim for antibodies >100

75
Q

How is Hepatitis C spread?

A

Blood, IVDU, Sex, Vertical

76
Q

85% of people infected wtih Hepatitis C develop ____________

A

Chronic silent infection

25% then develop cirrhosis
(4% develop cancer)

77
Q

How can Hep C be diagnosed on blood test?

A

Hep C RNA

Anti HCV

78
Q

What are the risk factors for the likelihood that Hep C will progress to cirrhosis or cancer?

A

Alcohol
Co-infection with Hep B or HIV
Older age
Male

79
Q

How can Hep C be treated?

A

Interferon
Ribavirin
Direct acting antivirals

80
Q

What type of virus is Hep D?

A

ssRNA with no envelope

Uses Hep B envelope

81
Q

How is Hep D transmitted?

A

Blood, IVDU, Sex

82
Q

What is the difference between Hep D co-infection and superinfection?

A

Co-infection: Hep B and D together; severe acute disease, low chronic risk

Super infection: Hep B carrier then Hep D infection; chronic Hep D, high risk of chronic liver disease

83
Q

How is Hep E spread?

A

Faeco-oral route. associated with pigs

84
Q

How many genotypes of Hep E virus are there?

A

4

1,2 and 4 in endemic areas
3 in non-endemic areas

85
Q

How can Hep E be treated?

A

Ribavirin

86
Q

What type of virus is HIV?

A 
Group 6 retrovirus
2 species (1 high virulence, 2 low virulence)
87
Q

How can HIV be transmitted?

A
  1. Sexual
  2. Parenteral- blood and needles
  3. Vertical
88
Q

What are the 3 stages of HIV?

A
  1. Seroconversion- acute, flu, rash, 2-4 weeks post infection
  2. Asymptomatic- slow decline in CD4 cells
  3. AIDS- CD4 count below 200, susceptible to virulent infections then opportunistic infections
89
Q

What percentage of people with HIV in the UK are undiagnosed?

A

12%

90
Q

What are the AIDs defining conditions?

A
  1. Tuberculosis
  2. Kaposi’s sarcoma
  3. Pneumocystis (fungi)
  4. Cryptosporidiosis (parasite)
  5. Cerebral toxoplasmosis (protozoa)
91
Q

What are the signs and symptoms of endocarditis?

A 
Fever, night sweats, weight loss
New murmur
Osler's nodes
Janeway lesions
Splinter haemorrhages
Anaemia
Splenomegaly
92
Q

Which organisms most commonly cause endocarditis?

A

Strep (alpha haemolytic)
Staph
Enterococci

93
Q

What is sepsis?

A

Life threatening organ dysfunction

Caused by disregulated host response to infection

94
Q

What is septic shock?

A

Sepsis with
1. Lactate >2 despite adequate fluids
or
2. Vasopressors needed to maintain MAP >65

95
Q

How should sepsis be treated?

A
  1. Broad spectrum antibiotics eg. Meropenem, Cephalosporin
  2. Fluids
  3. Oxygen
96
Q

What are the innate causes of immunodeficiency?

A
  1. Neutrophil defect eg. Chronic granulomatous disease
  2. NK defect
  3. Complement defect
  4. Cytokine defect
  5. Splenectomy
97
Q

What are the adaptive causes of immunodeficiency?

A
  1. B cell/antibody defect

2. T cell defect eg. Di George syndrome

98
Q

What are secondary causes of immunodeficiency?

A
  1. Splenectomy
  2. Chemotherapy
  3. AIDS
  4. Neutropenia
99
Q

Which infections do patients who have had a splenectomy usually present with?

A

Pneumococcus
Meningococcus
Malaria

(encapsulated bacteria)

100
Q

How do neutropenic patients present?

A

Bacterial or fungal infections without pus
Fever
Aplastic anaemia

101
Q

What is the chance of obtaining Hep C from a needle stick injury?

A

3%

102
Q

What type of bacteria is Salmonella?

A

Gram negative bacilli

103
Q

What type of bacteria is Enterococci?

A

Gram positive cocci

104
Q

What type of bacteria is Listeria?

A

Gram positive bacilli

105
Q

What type of bacteria is Neisseria?

A

Gram negative diplococci

106
Q

What type of organism is pneumocystis carinni?

A

Fungi

The most common infection in AIDs

107
Q

What is the most common species of malaria?

A

Plasmodum falciparum

108
Q

What is the treatment for malaria?

A

Quinine

Artesunate

109
Q

What is the incubation period for dengue fever?

A

7-14 days

110
Q

What is a Rickettsial infection?

A

Gram negative bacteria
Transmitted by ticks and fleas
Causes Typhus, Pox, African tick bite fever

111
Q

How is Rickettsial infection treated?

A

Doxycycline

112
Q

What is Histoplasmosis?

A

Infection caused by breathing in fungal spores from bird or bat droppings

113
Q

What is Schistosomiasis?

A

Parasitic flatworm
Lives in freshwater
Causes urinary and bowel infections

114
Q

What type of antibiotic is Doxycycline?

A

Tetracycline

Inhibits protein synthesis
Used for COPD, Chlamydia, malaria

115
Q

What type of antibiotic is Flucloxacillin?

A

Penicillin

116
Q

What type of antibiotic is Gentamicin?

A

Aminoglycoside

117
Q

What type of antibiotic is Erythromycin/Clarithromycin?

A

Macrolide

118
Q

What type of antibiotic is Metronidazole?

A

Quinolone

119
Q

What type of antibiotic is Trimethoprim?

A

Folate synthesis inhibitor

120
Q

Cephalosporins and Carbapenems are _________ spectrum antibiotics.

A

Broad

121
Q

Give examples of Glycopeptide antibiotics.

What can they be used for?

A

Teicoplanin
Vancomycin

MRSA, Complicated gram positive infections

122
Q

When should PEP be taken?

A

Ideally within 24 hours of potential exposure
Within 72 hours

Taken for 28 days

123
Q

Which drugs does PEP contain?

A
  1. Truvada (Emtricitbabine and Tenofovir)

2. Raltegravir

124
Q

Quinine and artesunate are used to treat which infection?

A

Malaria

Year 3 (22 decks)

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