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Principles > Microbiology > Flashcards

Microbiology Flashcards

1
Q

what are the 5 types of infectious agents?

A

1, parasites

  1. fungi
  2. bacteria
  3. viruses
  4. prion proteins
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2
Q

in relation to Staphylococcus aureus, what is the genus name?

A

Staphylococcus

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3
Q

in relation to Staphylococcus aureus, what is the species name?

A

aureus

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4
Q

what are prion proteins?

A

infectious proteins that have no DNA or RNA

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5
Q

what incurable brain infection do prion proteins cause?

A

Creutzfeld-Jacobs Disease

‘Mad cow diease’

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6
Q

why do surgical instruments used on patients with prion disease have do be destroyed?

A

prion proteins cannot be reliably removed by sterilisation or disinfection

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7
Q

what is the another name for prion diseases?

A

transmissible spongiform encephalopathies (TSEs)

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8
Q

What are viruses?

A

very small, obligate intracellular parasite

contain RNA or DNA, a protein coat +/- a lipid coat

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9
Q

what are the diagnostic methods for viruses?

A

Serology
PCR
Cell culture

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10
Q

what is serology?

A

antibody detection in blood

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11
Q

what does PCR detect and replicate millions of times?

A

DNA or RNA

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12
Q

how is DNA contained within a bacterial cell? (prokaryote)

A

within one tightly coile, double-stranded chromosome: nucleoid
plus extra circular rings of DNA in cytosol: plasmids

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13
Q

what are the flagellae of a bacterial cell for?

A

tail-like structure, for movement

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14
Q

what are the pili (fimbriae) of a bacterial cell for?

A

adhesion

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15
Q

what shape is a coccus bacteria?

A

round

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16
Q

what shape is a bacillus bacteria?

A

rod-shaped

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17
Q

what shape is a spirochaetes?

A

spirals

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18
Q

what does Gram stain actually stain?

A

bacterial cell wall

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19
Q

what colour does the Gram stain go if the bacteria is Gram positive?

A

purple

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20
Q

what colour does the Gram stain go if the bacteria is Gram negative?

A

pink

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21
Q

explain the cell wall of a gram positive bacterium

A

gram positives have a thick layer of peptidoglycan (cell wall) and then just deep to that have a cytoplasmic membrane made of phosholipids.

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22
Q

explain the cell wall of a gram negative bacterium

A

gram negatives have a outer cytoplasmic membrane, a middle thin layer peptidoglycan (cell wall) and an inner cytoplasmic membrane

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23
Q

what 2 types of bactteria dont stain well with gram stain?

A 
Mycobacterium Tuberculosis (atypical bacterium which causes TB)
Treponema pallidum (a spirochaete that causes sphyilis)
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24
Q

why does Mycobacterium tuberculosis not stain well with Gram stain?

A

has a waxy coat that doesn’t take up the stain

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25
Q

where are the 4 main places of normal bacterial flora?

A

upper respiratory tract
lower small intestine and large bowel
vagina
skin

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26
Q

what is a pathogen?

A

a harmful organism

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27
Q

what is a commensal?

A

an organism part of the normal flora

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28
Q

what is an opportunistic pathogen?

A

an organism that will usually only cause infection in an immunocompromised individual

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29
Q

what is a contaminant?

A

an organism that has got into a culture by accident

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30
Q

what is pathogenicity?

A

the ability of a microorganism to produce disease

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31
Q

what is virulence?

A

the degree of pathogenicity of an organism ie how easily can the organism cause disease

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32
Q

how do bacteria replicate?

A

binary fission

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33
Q

what 4 main factors do bacteria require for growth?

A
  1. food (any organic material)
  2. moisture
  3. correct temperature
  4. correct pH
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34
Q

for human pathogen what is generally the temperature and pH required for growth?

A

temperature- 37 degrees

pH- 7.4

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35
Q

what are the 4 phase to a bacterial growth curve?

A
  1. lag phase (BR slightly> DR)
  2. log phase (BR greatly> DR)
  3. stationary phase (BR = DR)
    4, death phase (BR < DR)
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36
Q

what are the 3 types of atmosphere a bacterium might require for growth?

A

aerobic (growth in presence of oxygen, most aerobes will grow in anaerobic conditions too, just less well)
microaerophilic (growth in an atmosphere with a reduced conc of oxygen and enriched CO2 conc)
anaerobic (growth in absence of oxygen, anaerobes is a term reserves for strict anaerobes)

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37
Q

what is an exotoxin?

A

toxin produced inside a bacteria cell and then exported from it

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38
Q

what type of bacteria make exotoxins?

A

gram positive bacteria

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39
Q

what is an endotoxin?

A

a toxin which is part of bacterial cell wall

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40
Q

what type of bacteria make endotoxins?

A

gram negative bacteria

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41
Q

what are the 2 main affects of bacterial toxins?

A

1, cause release of cytokines from immune cells

2. cause damage to red and white blood cells and make blood vessels ‘leaky’

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42
Q

what results from damage to RBC and WBC as well as ‘leaky blood’ vessel?

A

reduced clottting ability, reduced blood pressure resulting in sepis and septic shock

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43
Q

what type of bacteria can form spores?

A

Gram positive bacilli

eg Clostridium difficile and Bacillus anthracis

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44
Q

what are spores?

A

inactive, tough forms of bacteria which cannot replicate but can survive adverse conditions for many years and become active when conditions become more suitable

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45
Q

what 3 steps occur in spore formation?

A
  1. chromosome condensation
  2. septum formation
  3. calcium dipicolinate accumulation in the core
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46
Q

what does the core of a spore consist of?

A

cytoplasm plus contents

cytoplasmic membrane

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47
Q

what surrounds the core of a spore?

A

exosporium

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48
Q

what type of animals is anthrax usually a disease of?

A

cows and sheep

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49
Q

what are the 5 main diagnostic methods for bacteria?

A
  1. microscopy (gram film)
  2. culture
  3. antigen detection (eg in urine)
  4. serology (antibody detection in blood
  5. PCR
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50
Q

how long does microscopy take?

A

same day

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51
Q

how long does PCR take?

A

same day

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52
Q

how long does culture with sensitivity testing take?

A

2 days, 24 hours for organism growth, 24 hours for sensitivity

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53
Q

how long does serology take?

A

same day

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54
Q

how long does TB culture take?

A

4-12 weeks

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55
Q

what are the 2 types of fungi?

A

moulds

yeast

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56
Q

how do mould spores spread?

A

air currents

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57
Q

how do mould hyphae spread?

A

invade organic tissue

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58
Q

how do yeast reproduce?

A

budding

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59
Q

what type of treatment is used for fugnal infections?

A

anti-fungals

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60
Q

what is the most common cause of mould infection in humans?

A

Aspergillus spp

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61
Q

what type of people does Aspergillus sp usually target?

A

immunocomprimised

opportunistic

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62
Q

what is the most common cause of fungal infection in humans?

A

Candida spp (a type of yeast)

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63
Q

how do yeasts gram stain?

A

large Gram positive oval structures

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64
Q

how do moulds gram stain?

A

they dont

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65
Q

what are single celled parasites called?

A

protozoa

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66
Q

what are the 4 steilisation methods used?

A
  1. steam under pressure (autoclaves)
  2. dry heat in oven at 160 degrees for 1 hour+
  3. exposure to ethylene oxoid gas
  4. gamma-irradiation
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67
Q

compare sterilisation to disinfectants.

A

sterilisation removes 99.9% of micro-organisms

disinfection removes pathogenic microorganisms

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68
Q

what are the 2 ways of disinfection?

A

hot water

chemicals eg bleach, handwash, skin antiseptic

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69
Q

what does sp mean?

A

1 species of the genus

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70
Q

what does spp mean?

A

more than 1 species of the genus

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71
Q

what are the genus’s of the gram positive cocci?

A 
Streptoccci spp (and Enterococci sp)
Staphylococcus spp
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72
Q

what type of bacteria are Streptococcus spp and Enterococcus sp (with respects to the environment the prefer to live in)?

A

aerobic organisms
faculative anaerobic
(grow best aeobically but can grow anaerobically too if they need to)

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73
Q

what type of colonies do Streptococcus spp and Enterococcus sp like to grow in?

A

chains (strips)

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74
Q

how do you differentiate between Streptococcus spp and Enterococcus sp?

A

by the type of haemolysis

this is the only bacteria where it is important for classification

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75
Q

what types of haemolysis are there?

A

alpha- partial haemolysis
beta- complete haemolysis
gamma- no haemolysis

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76
Q

what does alpha haemolysis mean?

A

partial haemolysis that is caused by enzymes that denature the haemoglobin inside red blood cells causing greenish discolourisation round the colony

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77
Q

what does beta haemolysis mean?

A

complete haemolysis caused by enzymes (exotosins) that lyse the red blood cells completely clearing round the colony

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78
Q

what haemolytic class of Streptococci are the most pathogenic?

A

beta-haemolytic

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79
Q

what haemolytic class are Enterococcus sp?

A

non-haemolytic

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80
Q

what type of agar needs to be used for culturing bacteria when haemolysis is important?

A

blood agar

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81
Q

what 2 bacterial species are the alpha-haemolytic streptococci divided into?

A

Streptococcus pneumoniae

Strptococcus “viridans” (a group of different species)

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82
Q

what is the other name for Strptococcus pneumoniae?

A

pneumococcus

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83
Q

Describe what you would see on gram film for Streptococcus pneumoniae?

A

Gram positive cocci in short chains or pairs (diplococci)

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84
Q

what is the bacterium responsible for the most commonest cause of pneumonia?

A

Streptococcus pneumoniae

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85
Q

Describe what you would see on gram film for Streptococcus “viridans”?

A

Gram positive coci in chains

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86
Q

What sites are Strep. “viridans” common comensals of?

A

resp tract
bowel
vagina

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87
Q

What type of sites does Strep “viridans” cause infection in?

A

sterile site

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88
Q

What is a heart infection that can be caused by Strep “viridans”?

A 
infective endocarditis
(infection of the heart valves)
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89
Q

what 2 groups can the beta-haemolytic Streptococcus spp be divided into?

A

Group A strep (Strep. pyogenes)

Group B strep

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90
Q

What is the most pathogenic of all the Streptococci?

A

Strep. pyrogenes

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91
Q

what infections can Strep pyrogenes cause?

A
  • Streptococcal sore throat
  • Skin and soft tissue infections
  • Puerperal sepsis
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92
Q

what is the infection caused by Streptococcal sore throat?

A

tonsilitis

or scarlet fever if rash also present

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93
Q

What is the most severe skin and soft tissue infection caused by Strep. pyogenes?

A

necrotising fasciitis

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94
Q

what is puerperal sepsis?

A

a severs life-threatening infection in pregnant and recently post-natal women

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95
Q

Give 2 examples of Enterococci? (non-haemolytic streptococci)

A

Enterococcus faecalis

Enterococcus faecium

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96
Q

if Enterococcus faecalis and Enterococcus faecium are both part of normal bowel flora why can they sometimes cause problems? (eg UTI)

A

problematic if they get into sterile site

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97
Q

what are the very-antibiotic resistant strains of E. faecium which can cause outbreaks of infections in hospital?

A

VRE- vancomycin resistant enterococci

98
Q

What type of bacteria are the Staphylococci spp (with regards to the environment they like to live in?)

A

aerobes

faculative anaerobes

99
Q

how do Staph. spp colonise?

A

clusters

100
Q

how do we distinguish Staph. aureus from all the other staphylococci?

A

coagulase test

Staph. aureus is coagulase positive

101
Q

what is the collective name of staphylococci which are not Staph. aureus?

A

coagulase negative staphylococci

102
Q

what colour on the gram culture shows coagulation for Staph. aureus?

A

golden

coagulase negative is white

103
Q

what sites are the coagulase negative staphylococci common commensals of?

A

skin

104
Q

The coagulase negative staphylococci produce a surface polysaccharide slime. What is the function of this slime.

A

allows them to stick to plastic and other artificial material in the body

105
Q

what infections can coagulase negative stapylococci commonly cause?

A

prosthetic joint, prosthetic heart valve infection, IV catheter infection
(due to slime allowing them to stick onto artificial material in the body)

106
Q

what bacteria causes toxic shock syndrome?

A

Staph. aureus

107
Q

what toxin can some strains of Staph aureus produce that damage white blood cells?

A

Panton-Valentine leukocidin

108
Q

what is the collective name of toxins which act on the gut?

A

enterotoxins

109
Q

what can enterotoxins cause?

A

food poinsoning

110
Q

what antibiotic are MSSA (meticillin-sensitive Staph. aureus) sensitive to?

A

flucloxacillin

111
Q

what antibiotic are MRSA (meticillin-resistant Staph. aureus) resistant to?

A

all penicillins and all cephalosporins (+ others antibiotics)

112
Q

what bacteria is the commonest cause of skin, soft tissue and wound infections?

A

Staph aureus

113
Q

what bacteria is the commonest cause of bone and joint infection?

A

Staph aureus

114
Q

What types of Staph aureus cause food poisoning?

A

only enterotoxin-producing

115
Q

what is the treatment of choice for Staph. aureus infection? (MSSA)

A

Flucloxacillin

116
Q

what is the term for bacteria in the bloodstream?

A

bacteraemia

117
Q

where may Staph. aureus bacteraemia spread to?

A

heart valves, joints, kidneys, brain

118
Q

what is a common cause of Staph aureus bacteraemia in hospital?

A

infected IV catheters

119
Q

what is the name for a raised temperature (fever)?

A

pyrexia

120
Q

what is the name of a shivering attack as raised temperature drops? (a sign of pyrexia)

A

rigor

121
Q

despite a fever being an adaptive response to infection, what harm can it cause in young children?

A

febrile convulsions

122
Q

what specific prostaglandin, which is a response to cytokines and it released from the hypothalamus, causes an increase in the body’s thermal set point?

A

Prostaglandin E

123
Q

what does sepsis cause?

A
  1. leaky blood vessels- loss of fluid into issues- hypotension and tachycardia- poor tissue oxygen perfusion
  2. activated clotting system- blood clotting in tiny blood vessels which uses up all the clotting factors- increased risk of haemorrhage
124
Q

What are the 5 ways any infection can spread?

A 
the 5I's
Inhalation
Ingestion
Inoculation (direct and indirect)
mother to Infant
Intercourse
125
Q

what are the most frequently missed areas of hand washing?

A

back of the thumb
back of the fingertips
medially in between fingers
fingertips of 3/4

126
Q

what are the 5 momends for hand hygiene?

A
  1. before patient contact
  2. before aseptic task
  3. after body fluid exposure risk
  4. after patient contact
  5. after contact with patient surroundings
127
Q

what are the black bags for?

A

domestic waste

128
Q

what are the orange bags for?

A

clinical waste (no sharps)

129
Q

what is a FFP3 mask?

A

filter mask- airborne precautions

130
Q

some viruses also have a lipid envelope that surrounds their protein coat, where is this lipid envelope derived from?

A

derived from the membrane of the host cell that the virus grew in

131
Q

how many subunits are needed for a protein coat of a virus with icosahedral symmetry?

A

3 subunits
1 for apex
1 for centre of face
1 for edges

132
Q

what type of symmetry does the adenovirus have?

A

icosahedral symmetry

133
Q

how many subunits are needed for a protein coat of a virus with helical symmetry?

A

1 repeated subunit

134
Q

what main 4 infections can adenoviruses cause?

A

sore throats
conjunctivitis
gastroenteritis
pneumonia (v rare)

135
Q

what 6 steps are involved in the replication cycle of a virus?

A 
attachment to cell
entry into cell
uncoating of viral nucleic acid
nucleic acid and protein synthesis
assembly
release
136
Q

what are the 2 ways viruses can be released from host cells?

A

budding (providing cell with lipid envelope)

cell lysis

137
Q

what does selective toxicity of antibiotics mean?

A

more toxic for microbe than host cell

138
Q

what virus can have a role to play in cervical cancer?

A

HPV

139
Q

what viruses can have a role to play in primary hepatocellular carcinoma?

A

Hep B and Hep C

140
Q

what bacteria can have a role to play in gastric cancer?

A

Helicobacter pylori

141
Q

what does latency mean?

A

virus that can become inactive (no replication) but then reactivate later

142
Q

where in the body does varicella-zoster virus remain latent before reactivating? (shingles)

A

dorsal root ganglia

143
Q

what 3 ways indicate recent viral infection?

A

detection of virus specific IgM antibodies
detection of rising titre of virus specific IgG antibodies
detection of very high titre of virus specific IgG antibodies

144
Q

what are the genus are aerobic, Gram negative cocci?

A

Neisseria spp

145
Q

how do Neisseria spp appear on gram film?

A

Gram negative cocci in pairs (diplococci)

146
Q

what are the 2 important types of Neisseria?

A

Neisseria meningitidis

Neisseria gonorrhoeae

147
Q

what is Neisseria meningitidis the commonest cause of?

A

bacterial meningitis

148
Q

what does Neisseria gonorrhoeae cause?

A

gonorrhoea

149
Q

what is the collective name of aerobic, Gram negative, large bacilli?

A

coliforms

150
Q

with respect to their environmental conditions, what type of bacteria are coliforms?

A

aerobes

faculative anaerobes

151
Q

how are coliforms differentiated?

A
  1. biochemical reactions

2. antigenic structure (serotyping)

152
Q

what 2 types of serotyping are used for Coliforms?

A

O antigens- cell wall

H antigens- flagella

153
Q

are most strains of E.coli gut commensal coliforms or gut pathogens?

A

gut commensal coliforms

154
Q

are Klebsiella spp. gut commensal coliforms or gut pathogens?

A

gut commensal coliforms

155
Q

are Enterobacter spp gut commensal coliforms or gut pathogens?

A

gut commensal coliforms

156
Q

are Proteus spp. gut commensals or gut pathogens?

A

gut commensal coliforms

157
Q

are Salmonella spp. gut commensals or gut pathogens?

A

gut pathogens

158
Q

are Shigella spp. gut commensals or gut pathogens?

A

gut pathogens

159
Q

what type of Escherichia coli are gut pathogens?

A

Verotoxin procuding Escherichia coli (VTEC)

160
Q

what are 2 important types of verotoxin producing E. coli?

A

E. coli O157

E. coli O104

161
Q

what is the 1st line antibiotic used for treatment of infections caused by coliforms? (ie if they get into a normaly sterile site)

A

gentamicin

162
Q

why does Gram negative sepsis make patients very unwell very quickly? (generally slightly worse than Gram positive sepsis)

A

because gram negatives can release endotoxins from the Gram negative cell walls when they die

163
Q

what do Gram negative bacteria release from cell walls when they die which forms a ligand:receptor communication with Toll-like receptor 4? (Toll-like receptor 4 is found on the surface of macrophages)

A

Lipopolysaccharide

164
Q

what 2 types bacteria are strict aerobes?

A

Psudomonas aeruginois
Legionella pneumophila
(both gram negative bacilli)

165
Q

what type of bacteria is Haemophilus influenzae?

A

small Gram negative (cocco)bacillus aerobes

166
Q

what 2 important organisms are microaerophilic?

A 
Helicobacter pylori (Gram negative small curved bacilli)
Campylobacter spp (Gram negative spiral bacilli)
167
Q

what organism causes cholera?

A

Vibrio cholerae

168
Q

What 2 types of bacteria are strick anaerobes?

A

Clostridium spp

Bacteroides spp

169
Q

Describe Clostridium spp.

A

Gram positive anaerobic bacilli

170
Q

What can Clostridium difficile cause?

A

antibiotic-associated diarrhoea

171
Q

What can Clostridium perfringens cause?

A

“gas” gangrene- a severe soft tissue infection following contamination of a wound

172
Q

What can Clostridium tetani cause?

A

Tetanus- a fatal paralytic illness

173
Q

Describe Bacteroides spp.

A

Gram negative anaerobic bacili

174
Q

what is the 1st line treatment for infections caused by anaerobes?

A

metronidazole

175
Q

how are Mycobacteria stained?

A

Acid-alcohol fast bacilli

176
Q

what are 2 spirochates bacteria that do not stain with Gram stain?

A 
Treponema pallidum (causes syphilis)
Borrelia burgdorferi (Lyme disease, spread by sheep ticks)
177
Q

what 2 ways does genetic variation occur in bacteria?

A

mutation

gene transfer

178
Q

what are the 3 ways of gene transfer within micro-organisms?

A
  1. transformation
  2. conjugation
  3. transduction
179
Q

What is transformation?

a way of gene transfer

A

when DNA released from dead bacteria is taken up by living bacteria and incorporated into plasmids of nucleoid

180
Q

what is conjugation?

a way of gene transfer?

A

bacterial sex

a sex pilus is produced by one bacteria through withich plasmid DNA can be transferred

181
Q

what is transduction?

a way of gene transfer?

A

when viruses infect bacteria and transfer bits of DNA from one bacterium to another

182
Q

what are the 4 mechanisms of antibiotiv resistance?

A
  1. production of enxymes that destroy antibiotics
  2. altered antibiotic binding sites
  3. alteration of cell wall porins
  4. up-regulation of efflux pumps
183
Q

what do efflux pumps do?

A

pump out unwanted toxins

184
Q

which antibiotics are bacteria which produce beta-lactamase resistant to?

A

early penicillins (eg amoxicillin)

185
Q

which antibiotics are bacteria which produce extended spectrum beta-lactamase resistant to?

A

all penicillins and cephlasporins

186
Q

wich antibiotics are bacteria which produce carbapenemase resistant to?

A

all penicillns, all cephlasporins and carbapenems

187
Q

alteration of what antibiotic binding site resulted in Staph aureus becoming resistant to flucloxacillin? (MRSA)

A

PBP 2

penicillin binding protein 2

188
Q

if an antibiotic is given PO how long will it take to reach peak serum levels?

A

1 hour

189
Q

if an antibiotic is given IV how long will it take to reach peak serum levels/

A

15 minutes

190
Q

what does synergy mean?

A

effect of combination is better than the combined effect of each drug alone

191
Q

what are the 3 reasons antibiotics are sometimes given in combinations?

A
  1. to cover broad range of possible infecting organisms
  2. to prevent the development of resistance
  3. for synergistic effect
192
Q

which antibiotics act on the bacterial cell wall?

A

penicillins
cephlasporins
glycopeptides

193
Q

what group of antibiotic do penicillin, flucloxacillin, amoxicillin, temocillin, co-amoxiclav and piperacillin belong to?

A

penicillins

194
Q

what group of antibiotic does ceftriaxone belong to?

A

cephlasporin

195
Q

what group of antibiotic do vancomycin and teicoplanin belong to?

A

glycopeptides

196
Q

what do penicillins do to the bacterial cell wall?

A

inhibit cell wall synthesis by preventing cross-linking of peptidoglycan subunits

197
Q

what are the 2 draw backs of penicillin?

A
  1. allergies to penicillin (allergy to one means allergy to them all)
  2. rapid excretion via the kidneys so frequent dosing is needed (4-6 times per day)
198
Q

what are the 3 types of penicillin? (different routes of administration)

A
  1. benzylpenicillin (penicillin G): IV
  2. phenoxymethyl penicillin (penicillin V): oral
  3. benzathine penicillin (IM)
199
Q

what is the advantage of benzathine penicillin (IM)?

A

long acting

200
Q

what is the functional group of penicillins?

A

beta-lactam ring

201
Q

what type of bacteria does flucloxacillin cover? (IV, oral)

A

Gram positive

useful for Staph and Strep only

202
Q

what type of bacteria does amoxicillin cover? (IV, oral)

A

Gram positive and Gram negative

203
Q

what is co-amoxiclav? (IV, oral)

A

amoxicillin plus clavulanic acid

204
Q

what type of bacteria does temocillin cover?

A

Gram negative organisms

useful for coliforms only

205
Q

what does clavulanic acid do?

A

inhibits the action of beta-lactamase enzyme, no antibiotic properties of its own

206
Q

are penicillins bactericidal or bacteriostatic?

A

bactericidal

207
Q

are cephlasporins bactericidal or bacteriostatic?

A

bactericidal

208
Q

why are cephalosporins avoided in tayside?

A

so broad spectrum that they affect normal bowel flora and allow over growth of C dif

209
Q

as the generations of cephlasporins increase what happens to the spectrum of activity?

A

increases as well

ie 3rd > 2nd > 1st

210
Q

how are vancomycin and teicoplanin administered?

A

IV

211
Q

what do cephlasporins do to the bacterial cell wall?

A

inhibit cell wall synthesis

212
Q

are glycopeptides bactericidal or bacteriostatic?

A

bactericidal

213
Q

what do glycopeptides do to the bacterial cell wall?

A

bind to the end of the growing pentapeptid chain, preventing cross linking and thus weakening the bacterial cell wall

214
Q

when should you avoid use of vancomycin?

A

in patients with kidney failure (toxic levels will build up in the blood and cause further kidney damage)

215
Q

what type of cell wall does the bacteria need to have for glycopeptides to be effective?

A

Gram positive

therefore no Gram negative effect

216
Q

what antibiotics inhibit protein synthesis?

A

macrolides
tetracyclines
aminoglycosides

217
Q

which antibiotic group do erythromycin, clarithromycin and azithromycin belong to?

A

macrolides

218
Q

which antibiotic group do tetracycline, doxycycline, minocycline belong to?

A

tetracyclines

219
Q

which antibiotic group does gentamicin belong to?

A

aminoglycosides

220
Q

are macrolides bactericidal or bacteriostatic?

A

bacteriostatic

proteins synthesis can resume once antibiotic is removed

221
Q

are tetracyclines bactericidal or bacteriostatic?

A

bacteriostatic

protein synthesis can resume once antibiotic is removed

222
Q

are aminoglycosides bactericidal or bacteriostatic?

A

bactericidal

unlike other protein synthesis inhibitors, binding of these antibiotics to the ribosome is lethal

223
Q

how are macrolides excreted?

A

via liver, biliary tract and into faeces

not in urine

224
Q

how must gentamicin be administered?

A

IV (occasionally IM)

225
Q

what is gentamicin used for?

A

gram negative aerobic organisms such as coliforms and pseudomonas

226
Q

how is gentamycin excreted?

A

urine

227
Q

why do you need to monitor blood levels of gentamicin?

A

toxicity- causes damage to the kidneys and the vestibulocochlear cranial nerve (deafness and dizziness)

228
Q

what antibiotics act on bacterial DNA?

A

metronidazole
trimethoprim
co-trimoxazole
fluoroquinolones

229
Q

how is metronidazole administered?

A

oral, IV

230
Q

how does metronidazole work?

A

acts by causing strand breakage of bacterial DNA

231
Q

what is metronidazole used for?

A

anaerobic infections

some protozoal

232
Q

how is trimethoprim administered?

A

PO

233
Q

how does trimethoprim work?

A

inhibits bacterial folic acid synthesis

234
Q

what is co-timoxazole?

A

trimethoprim + sulphamethoxazole

235
Q

what does trimethoprim work on?

A

Gram negative and some Gram positive bacteria

236
Q

how is trimethoprim excreted?

A

via the urine

237
Q

how do fluoroquinolones work?

A

by preventing supercoiling of bacterial DNA

238
Q

are fluoroquinolones bactericidal or bacteriostatic?

A

bactericidal

239
Q

why is the use of fluoroquinolones severely restricted in Tayside?

A

C diff risk

240
Q

What are the 4 “C£ antibiotics highly associated with C. diff?

A

Cephalosporins
Co-amoxiclav
Ciprofloxacin
Clindamycin

Principles (8 decks)

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