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1
Q

What is the difference between sterilisation and disinfection?

A

sterilisation: the removal or inactivation of ALL microorganisms from an article (including bacterial and fungal spores)

Disinfection: the removal of SOME microorganisms from an article (usually doesn’t include bacterial spores)

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2
Q

Define asepsis

A

asepsis is the state of being free from living organisms

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3
Q

Define antiseptic

A

an antiseptic is a substance which destroys or inhibits growth of micro-organisms. it can be applied to living tissues

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4
Q

What are the four main methods of sterilisation?

A
  • heat
  • irradiation
  • gaseous process (eg ethylene oxide)
  • filtration
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5
Q

What are the five methods of disinfection?

A
  • Moist heat (at 70-80 degrees C)
  • Ultraviolet Radiation
  • Gases (formaldehyde gas)
  • Filtration
  • Chemicals
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6
Q

What are the seven classes of disinfectants?

A
  • Alcohols
  • Aldehydes
  • Biguanides
  • Halogens
  • Phenolics
  • Peroxygenated compounds
  • Surface-active agents (eg quaternary ammonium compounds)
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7
Q

True or false,

Gram-positive bacteria are more sensitive to disinfectants than Gram-negative bacteria

A

TRUE

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8
Q

True or False,

Enveloped or lipophilic viruses eg HIV, are relatively insensitive to disinfectants

A

FALSE

they are SENSITIVE to disinfectants

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9
Q

True or false,

Hepatitis B virus is fairly resistant to disinfectants

A

TRUE

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10
Q

True or false,

Bacterial spores have greater resistance to disinfectants that fungal spores

A

TRUE

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11
Q

Which bacterium is the most common cause of post operative wound infections?

A

Staphylococcus aureus

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12
Q

Which four tests are carried out to distinguis between Staphylococcus aureus bacterium and other gram positive cocci?

A
  • catalase
  • glucose fermentation
  • coagulase
  • mannitol fermentation
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13
Q

What are the main diagnostic features of Staphylococcus aureus coagulase positive bacterium?

A
  • pigmented colonies (carotenoid pigments)
  • production of extra cellular coagulase
  • production of nucleases that breakdown DNA
  • production of cell-surface associated enzymes eg bound coagulase or clumping factor
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14
Q

What is the difference between a gram positive and gram negative bacterium?

A

gram positive have a thicker peptidoglycan layer in their cell wall and have an inner lipid membrane layer

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15
Q

What two invasins does the Staphylococcus aureus bacterium produce and what are their functions?

A

coagulase: converts fibrinogen into fibrin = clot formation
staphylokinase: converts plasminogen into plasmin = breaks down clots

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16
Q

Which bacterium causes the following infections:

mastitis
osteomyelitis
pneumonia 
endocarditis 
impetigo
A

Staphylococcus aureus

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17
Q

What do the enterotoxins/ pyrogenic exotoxins produced from S. aureus induce?

A

these are super antigens that induce a potent T-cell response

they cause nausea, vomiting and diarrhoea

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18
Q

What do epidermolytic toxins produced from S. aureus do?

A

cause blistering diseases such as impetigo, scalded skin syndrome, etc

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19
Q

Which S. aureus toxin/enzyme destroys red blood cells, phagocytic cells and other tissues?

a) TSST-1
b) Haemolysins
c) Epidermolytic toxins
d) Panton-Valentine Leucocidin
e) Hyaluronidase

A

b) Haemolysins

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20
Q

Which S. aureus toxin/enzyme destroys white blood cells?

a) TSST-1
b) Haemolysins
c) Epidermolytic toxins
d) Panton-Valentine Leucocidin
e) Hyaluronidase

A

d) Panton-Valentine Leucocidin

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21
Q

What is the action of Protein A found on the cell surface of S. aureus bacterium do?

A

reacts with the Fc region of the IgG antibodies

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22
Q

Which cell wall polymer found on S. aureus inhibits inflammatory response ?

a) Lipoteichoic acid
b) Protein A
c) Peptidoglycan
d) fibronectin-binding factor
e) capsule

A

c) Peptidoglycan

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23
Q

List the three ways of how S. aureus resists antibiotics

A
  • production of enzyme penicillinase that opens the beta-lactam ring inactivating the drug
  • mutation of the essential penicillin binding protein on bacterial cell envelope
  • glycopeptide resistance. increased cell wall thickness
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24
Q

Which penicillin drug is stable to penicillinase ?

a) Benzyl Penicillin
b) Amoxicillin
c) Flucoxacillin
d) Erythromycin
e) Vancomycin

A

c) Flucoxacillin

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25
Which drug is used to treat MRSA ? a) Benzyl Penicillin b) Amoxicillin c) Flucoxacillin d) Erythromycin e) Vancomycin
e) Vancomycin
26
Which bacterium usually is associated with infections of implants such as pacemakers,cardiac valves and artificial joints?
Staphylococcus aureus coagulase negative bacterium
27
What are acid-fast bacterium?
Bacteria containing mycolic acid in their cell wall
28
How are acid-fast bacteria distinguished from non-acid fast bacteria?
By the Ziehl-Neelsen stain 1) carbol fuchsin stains bacteria red 2) acid alcohol wash decolourises non acid-fast bacteria 3) Malachite green dye stains decolourised non acid-fast bacteria acid fast bacteria = red non acid fast bacteria = green
29
Which microorganism causes whooping cough? a) Mycoplasma pneumoniae b) Haemophilus influenzae c) Streptococcus pneumoniae d) Pseudomonas aeruginosa e) B. pertussis
e) B. pertussis
30
Which microorganism causes bronchiectasis? a) Mycoplasma pneumoniae b) Haemophilus influenzae c) Streptococcus pneumoniae d) Pseudomonas aeruginosa e) B. pertussis
b) Haemophilus influenzae | d) Pseudomonas aeruginosa
31
Which microorganism causes acute bronchitis? a) Mycoplasma pneumoniae b) Haemophilus influenzae c) Streptococcus pneumoniae d) Pseudomonas aeruginosa e) B. pertussis
a) Mycoplasma pneumoniae
32
Which microorganism causes chronic bronchitis? a) Mycoplasma pneumoniae b) Haemophilus influenzae c) Streptococcus pneumoniae d) Pseudomonas aeruginosa e) B. pertussis
b) Haemophilus influenzae | c) Streptococcus pneumoniae
33
What is bronchiectasis?
weakened and dilated bronchus
34
Is the bacterium Haemophilis influenzae gram positive or negative?
Gram negative
35
What are the distinguishing features of Mycobacterium tuberculosis?
- red stain on Ziehl-Neelsen stain - growth o Lowenstein-Jensen slopes as 'rough, buff and tough' colonies - slow growing
36
What is the difference between primary and post-primary TB?
PRIMARY: results in either dead/latent M. tuberculosis bacterium residing in the primary complex or progresses to primary infection = miliary TB eg meningitis SECONDARY: reactivation of latent M. tuberculosis in primary complex resulting in large granulomas with caseation and miliary TB
37
Regarding TB, what is a primary complex?
Primary complex refers to the granuloma and infected hilar lymph nodes
38
How can you diagnose TB?
- Tuberculin test ( Mantoux test) - tuberculin injected intracutaneously = inflammatory response = positive - Microscopy : Ziehl-Neelsen stain = red = positive - Culture: Lowenstein-Jensen slope = rough, buff and tough colonies - Chest X-ray
39
What vaccine is used for controlling/preventing TB?
BCG vaccine uses a live, attenuated strain of M.bovis
40
Describe the treatment of TB
continuous phase (6-9 months) of Rifampicin or Isoniazide
41
Which tests are performed to distinguish between toxigenic and commensal strains of corynebacteria?
Elek Test | Schick Test
42
Which bacterium is not gram negative? a) Haemophilis influenza b) Legionella pneumophila c) Corynebacterium diphtheriae d) Bordetella pertussis e) Mycobacterium tuberculosis
c) Corynebacterium diphtheriae (it is a gram positive bacterium )
43
Define saprophytes
organisms that live on dead/decaying organic matter
44
What is the difference between moulds and yeasts?
moulds have hyphae that when interwoven form mycelium. They reproduce by means of spores Yeasts are predominantly unicellular and reproduce by budding.
45
What are dermatophytes?
fungi that are able to colonise and digest keratin.
46
Define dimoprhic fungi
Fungi that can be mycelial or yeast phase depending on growth conditions
47
Which form of candidiasis presents as loss of central papillae on the dorsum tongue in the midline ? a) acute pseudomembranous candidiasis b) acute erythematous candidiasis c) chronic erythematous candidiasis d) chronic hyperplastic candidiasis (candidiasis leukoplakia) e) median rhomboid glossitis f) angular cheilitis
e) median rhomboid glossitis
48
Which form of candidiasis is brought upon denture wearers? a) acute pseudomembranous candidiasis b) acute erythematous candidiasis c) chronic erythematous candidiasis d) chronic hyperplastic candidiasis (candidiasis leukoplakia) e) median rhomboid glossitis f) angular cheilitis
c) chronic erythematous candidiasis
49
what factors predispose to a UTI?(6)
- urinary flow disruption - urine reflux - incomplete bladder emptying - shorter urethra in women - male infant faecal contamination - diabetes
50
whats the most common organism to cause UTIs?
e- coli
51
what are the virulent factors of E coli that cause UTIs?
pili for attachment allows resistance to washing action of urine capsular K antigen= antiphagocytic and pyelonephritis haemolysin = membrane damaging
52
what are the clinical features of lower UTI? (4)
dysuria pain cloudy urine prostatitis in males
53
what symptoms do upper UTI infections display?
``` dysuria pain cloudy urea prostitis in men fever ```
54
What culture medium is used to diagnose for E coli?
macConkeys agar = pink = lactose fermenting or CLED = yellow colonies
55
true or false | ziehl neelson stain can be used for M.tuberculosis and A. isrealii
TRUE
56
Give 6 features of Actinomycoses
``` gram positive filamentous facultative anaerobe commensal acid fast sulphur granules = diagnostic feature ```
57
List 6 oral infections caused by Candidia albicans
- pseudomembranous candidiasis - candidal leukoplakia - acute erythematous candidiasis (drug induced) - denture induced stomatitis - angular chielitis - median rhomboid glossitis
58
List 5 local and 5 systemic predisposing factors to candidal infections
local: - dentures - impaired salivary flow eg xerostomia/sjogrens - inhaled steroids - oral cancer - trauma systemic; - diabetes mellitus - cushings - broad spectrum antibiotics - malignancy/immunocompromised - nutritional deficiencies
59
what four things are implicated in diagnosis of candida albicans?
sabourauds agar growth germ tube test: growth of hyphae chlamydospores gram staining = positive budding yeast + mycelium
60
list strep pyogens virulence factors
(smashed) Streptokinases A+B M protein Anti C5a peptidase Streptolysin O+S Hyaluronidase Exotoxins SPE A,B,C DNases
61
list diseases caused by strep pyogens
(nipples) Necrotising fasciitis Impetigo Pharyngitis/tonsilitis Pneumonia Lymphagentitis Erysipilas and cellulitis Scarlet fever rheumatic fever post strep glomerulonephritis erythema nodosum
62
what are the differences between strep and staph
strep: - chain forming cocci - catalase negative - DNase negative - fastidous staph: - clustered cocci - catalase positive - DNase positive - non fastidous
63
Notes on E.coli: (6)
- Gram -ve - lactose fermenting - GIT commensal - most common cause for UTIs - O, K H antigens on capsules - pathogenic species: EPEC, ETEC, EIEC, VTEC
64
Which gram -ve species is described as comma shaped rods? a) E.coli b) actinomyces c) vibrio d) proteus e) pseudomonas
c) vibrio
65
Which species produces large amounts of urease? a) E. coli b) vibrio cholerae c) helicobacter pylori d) pseudomonas aureginosa
c) helicobacter pylori
66
describe the difference in disinfection and sterilisation and their methods
sterilisation: the complete removal of all microorganisms - moist heat >100degrees (autoclave/chemicalve) - dry heat (red heat/hotsalt/ovens/incineration) - irradiation (x-rays, gamma rays, accerated electrons) - gaseous process ( ethylene oxide) - filter disinfection: the removal of some microorgansism - moist heat 70-80degrees - ultraviolet radiation - gaseous process (formaldehyde) - filtration - chemicals

Year 2 (10 decks)

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