Microbiology Flashcards
0
Q
What part of “Herpes simplex” is the species name?
A
simplex
1
Q
What part of “Staphylococcus aureus” is the genus name?
A
Staphylococcus
2
Q
What are the names of infectious proteins that have no DNA or RNA?
A
Prion proteins
3
Q
What are responsible for transmissible spongiform encephalopathies such as Creutzfeldt-Jakob Disease (CJD)?
A
Prion proteins
4
Q
What is the name of the protein coat that viruses have?
A
Capsomere
5
Q
What can be described as obligate intracellular parasites?
A
Viruses
6
Q
What three methods can be used to diagnose viruses?
A
Cell culture
Antigen or antibody detection in blood (serology)
Polymerase chain reaction to detect DNA or RNA
7
Q
What shape are coccus bacteria?
A
Round
8
Q
What shape are bacillus bacteria?
A
Rod-shaped
9
Q
What shape are spirochaetes?
A
Spirals
10
Q
What part of bacteria do Gram stains stain?
A
The bacterial cell wall
11
Q
What colour will Gram positive bacteria stain?
A
Purple
12
Q
What colour will Gram negative stain?
A
Pink
13
Q
Which two organisms do not stain well with Gram stain?
A
- Mycobacterium tuberculosis (waxy coat)
2. Treponema pallidum (a spirochaete organism that causes syphilis)
14
Q
What has the definition of a harmful organism?
A
A pathogen
15
Q
What is an organism that is part of the normal flora?c
A
Commensal
16
Q
What is an opportunistic pathogen?
A
An organisms that will likely only cause infection in an immunocompromised individual.
17
Q
What is the ability of a microorganism to produce disease?
A
Pathogenicity
18
Q
What is the word for the degree of pathogenicity of an organism?
A
Virulence
19
Q
In what way do bacteria replicate?
A
Binary fission
20
Q
How often can bacteria replicate their numbers?
A
Every 20 minutes
21
Q
What are the 4 phases of bacterial growth?
A
Lag phase
Log phase
Stationary phase
Death phase
22
Q
What 3 types of atmosphere for bacterial growth are there?
A
Aerobic
Microaerophilic
Anaerobic
23
Q
What atmosphere has a reduced concentration of oxygen and enriched with CO2?
A
Microaerophilic
24
Which type of bacteria produce exotoxins?
Gram positive bacteria
25
What are usually produced inside a Gram positive cell and then exported from it?
Exotoxin
26
What toxin do Gram negative bacteria produce?
Endotoxin
27
What toxin is part of the Gram negative bacterial cell wall?
Endotoxin
28
What, released from bacteria, interact with cells of the immune system causing release of cytokines?
Toxins
29
What 3 effects do some toxins have on the body?
Damage white and red blood cells
Make small blood vessels leaky causing decreased BP
Affect blood clotting
All can lead to sepsis
30
What endotoxin is found in Gram-negative bacterial cell walls?
LPS
31
What can some Gram positive bacilli form?
Spores
32
What are the 5 methods for diagnosing bacteria?
1. Microscopy - Gram stained film
2. Culture
3. Detection of antigen (e.g. in urine)
4. Detection of antibodies in blood (serology)
5. Molecular methods such as PCR
33
How long does a TB culture take?
4 - 12 weeks
34
What two things do moulds produce?
Spores - spread in air currents
| Hyphae - invade organic tissue
35
What is single celled and reproduces by budding?
Yeasts
36
Name a mould of fungi?
Aspergillus
37
Do Gram stains stain Aspergillus spp.?
No
38
Name a common yeast fungus?
Candida spp.
39
How do yeasts Gram stain?
As large positive oval structures
40
What is the term for the dstruction nad removal of 99.9% of micro-organisms and spores?
Sterilisation
41
What is sterilisation used for?
Dressings, surgical instruments
42
What are the 4 methods of sterilisation?
1. Autoclave
2. Dry heat in oven at 160
3. Exposure to ethylene oxoid gas
4. Irradiation (gamma-irradiation)
43
What is the term for the removal or destruction of pathogenic micro-organisms enough to make an item safe?
Disinfection
44
What 3 chemicals are used for disinfection?
1. Hypochlorite - bleach
2. Chlorohexidine - handwash
3. Povidone iodine - skin antiseptic
45
What does the "us" mean at the end of "Staphylococcus"?
Singular term i.e. one organism
46
What does "i" at the end of "Staphylococci" mean?
The plural term, more than one
47
What does the "sp." at the end of Staphylococcus sp. mean?
1 species of Staph
48
What does the "spp." at the end of Staphylococcus spp. mean?
More than one species of Staph.
49
How do streptococcus and enterococcus grow best?
Aerobically (also can facultatively anaerobically grow)
50
How would Streptococcus and Enterococcus be described?
As Gram positive cocci in chains (streptococci come in strips)
51
How are streptococcus and enterococcus differentiated initially?
By the type of haemolysis seen on growth on blood agar
52
What is another term for alpha haemolysis?
Partial haemolysis
53
What is another term for beta haemolysis?
Complete haemolysis
54
Haemolysis is only important for the classification of what?
Streptococci
55
What is caused by enzymes that denature the haemoglobin inside red blood cells causing greenish discolouration round the colony?
Alpha haemolysis
56
What is caused by enzymes that lyse red blood cells causing complete clearing round the colony?
Beta-haemolysis
57
What occurs in gamma-haemolysis?
No haemolysis
58
What colouration does denaturised haemoglobin go, and what is this as a result of?
Green discolouration as a result of alpha haemolysis
59
What two can alpha-haemolytic streptococci be differentiated into?
Streptococcus pneumoniae
| Streptococcus "viridans" group
60
How would you describe Streptococcus pneumoniae?
Gram positive cocci in short chains or pairs
61
How would you describe Streptococcus viridans?
Gram positive cocci in chains on microscopy
62
What heart condition may be caused by Streptococcus "viridans" group?
Infective endocarditis
63
What are the most pathogenic Streptococci?
Beta-haemolytic
64
What do Beta-haemolytic streptococci produce which lyse red blood cells?
Exotoxins
65
How are the beta-haemolytic streptococci further classified?
Into group A strep and group B strep
66
What two infections can Streptococcus group A cause?
Streptococcal sore throat (tonsilitis) - if rash present = scarlet fever
Necrotising fasciitis - skin and soft tissue infection
Puerperal sepsis - infection in pregnant women
67
What are all strains of group A streptococcus still sensitive to?
Penicillin
68
What is the most important group of non-haemolytic streptococci?
Enterococci
69
Name a common cause of urinary tract infection?
Enterococci
70
What are most strains of E. faecalis sensitive to?
Amoxicillin (not penicillin)
71
Name a very resistant type of Enterocci? (vancomycin resistant enterococci)
E. faecium
72
How would you describe Staphylococci?
Gram positive cocci in grape-like clusters
73
How do we distinguish Staph. aureus from all other Staphylococci?
We use the coagulase test
74
What would the result of a Staph. aureus positive coagulase test show?
Golden
75
Name two species in the coagulase negative staphylococci group?
1. Staph. epidermidis
| 2. Staph hominis
76
What are the coagulase negative Staphylococci a common cause of?
Prosthetic joint and prosthetic heart valve infection and intravenous catheter infection
77
What organism type causes Toxic Shock Syndrome Toxin?
Staphylococcus aureus
78
Where do enterotoxins act?
On the gut
79
What are strains of Staphylococcus aureus that are sensitive to flucloxacillin called?
MSSA - Meticillin-Sensitive Staph Aureus
80
What are meticillin-resistant Staph aureus strains resistant to?
All penicillins
| All cephalosporins
81
What is the most common cause of wound infection?
Staph. aureus
82
What is the treatment of choice for Staph. aureus?
Flucloxacillin
83
What is bacteraemia?
Bacteria in the blood stream
84
What is one of the commonest causes of bacteraemia?
Staph. aureus bacteraemia
85
What is pyrexia?
Raised temperature
86
What is fever defined as?
Temperature > 38
87
During fever production, what do macrophages release?
Cytokines into the bloodstream
88
During fever production, where do released cytoklines travel to?
The anterior hypothalamus
89
During fever production, once the cytokines have travelled to the hypothalamus - what is released?
Prostaglandin E which increases body's thermal set point
90
During sepsis, what happens to small blood vessels?
The become leaky and lose fluid into tissues
91
In sepsis what happens to the blood volume?
It lowers
92
How do Gram negative cocci appear on Gram film?
In pairs (diplococci)
93
What are two Gram negative cocci?
1. Neisseria meningitidis
| 2. Neisseria gonorrhoeae
94
What is the term used to describe species of Gram negative bacilli that look like E.coli on Gram film and when cultured on blood agar?
The coliforms
95
How do the coliforms grow best?
Aerobically
96
In what 2 ways are coliforms differentiated from each other by?
1. Biochemical reactions
| 2. Antigenic structure of cell wall (serotyping) - O antigens (cell wall) and H antigen (flagella)
97
Where are O antigens found?
Cell wall
98
Where are H antigens found?
Flagella
99
Name 4 gut commensal coliforms?
1. E.coli
2. Klebsiella spp.
3. Enterobacter spp.
4. Proteus spp
100
Name 3 gut pathogens
1. Salmonella spp.
2. Shigella spp.
3. Verotixin (VTEC) producing E.coli
101
Name 3 types if infection that can occur when coliforms get into normally sterile sites
1. Urinary tract infection
2. Periotnitis
3. Biliary tract infection
102
What is the first line antibiotic used for the treatment of Coliforms?
Gentamicin
103
Why do patients with coliform (gram negative) sepsis become very unwell very quickly?
Because of the endotoxin released from the Gram negative cell wall when the bacteria die
104
Name three other types of aerobic Gram negative bacilli
1. Strict aerobes
2. Spiral or curved Gram negative bacilli
3. Haemophilus influenzae
105
Name two strict aerobes
Pseuodomonas aeruginosa
| Legionella pneumophila
106
Name 3 spiral or curved Gram negative bacilli
1. Vibrio cholerae - causes cholera
2. Campylobcater spp - commonest cause of bacterial diarrhoea
3. Helicobacter pylori - infects stomach and causes gastritis nad duodenual ulcers
107
Name two groups of strict anaerobes
1. Clostridium spp.
| 2. Bacteriodes spp.
108
How would you describe Clostridium spp.?
Gram positive anerobic bacilii
109
What do Clostridium spp. produce that can cause severe tissue damage?
Exotoxins
110
What does Clostridium perfringens cause?
Gas gangrene
111
What does Clostridium tetani cause?
Tetanus
112
How would you describe Bacteroides spp, ?
Gram negative anaerobic bacilli
113
What is the first line treatment for infections caused by anaerobes?
Metronidazole
114
What method is used to stain Mycobacteria?
Acid fast bacilli
115
What type of spirochaetes other than Treponema pallidum does not stain?
Borrelia burgdorferi - Lyme disease
116
What is the term for when DNA released from dead bacteria can be taken up by living bacteria and incorporated into plasmids or the bacterial chromosome?
Transformation
117
What is the term for "bacterial sex" where a sex pilus (fimbria) is produced by one bacteria through which plasmid DNA can be transferred?
Conjugation
118
What is the term for viruses that infect bacteria can transfer bits of DNA from one bacterium to another?
Transduction
119
What are 3 genetic variations of bacteria?
Transforamtion
Conjugation
Transduction
120
What does genetic variation often result in?
Bacteria becoming resistant to antibiotics
121
Give 4 mechanisms of antibiotic resistance?
1. Production of enzymes that destroy antibiotics
2. Altered antibiotic binding site
3. Alteration of cell wall porins
4. Up-regulation of efflux pumps
122
What 3 enzymes can destroy antibiotics?
1. Beta-lactamase
2. Extended spectrum beta-lactamase
3. Carbapenemase
123
What is beta-lactamase resistant to?
Amoxicillin
124
What is extended spectrum beta-lactamase resistant to?
All penicillins and cephalosporins
125
What is carbapenemase resistant to?
All cephalosporins
All penicillins
All carbapenems
126
What is a common mechanism of resistant in fungi such as Candida spp.?
Up-regulation of efflux pumps
127
What are the 5 ways any infection can spread?
```
Inhalation
Ingestion
Inoculation
mother to Infant
Intercourse
```
128
Where is the most frequently missed site when hand washing?
Thumb, between thumb and index finger and tips of fingers
129
What are black bags for?
Domestic waste
130
What are orange bags for?
Clinical waste
131
What 4 things are viruses composed of?
Protein spikes
Protein coat
Nucleic acid
Envelope
132
What type of symmetry does adenovirus have?
Icosahedral
133
What is the cause of oral herpes?
Herpes simplex virus
134
What happens in the attachment phase of viral infection?
Viruses interact with specific receptors in the target cell
135
What happens during the entry phase of virus infection?
Fusion of viral and cell membranes or endocytosis
136
How may non-enveloped viruses enter a cell?
By pinocytosis
137
What happens in the uncoating stage of virus infeciton?
Viral nucleic acid is released from the capsid
138
What stage of viral infection occurs after uncoating?
Nucleic acid and protein synthesis
139
What occurs in the nucleic acid and protein synthesis stage of virus infeciton?
Nucleic acid produces new viral proteins - host ribosomes and polymerases are used
Viral nucleic acid is replicated into pregeny genomes
140
What happens in the assembly stage of viral infection?
Nucleic acid and proteins are packaged together
141
What stage of the virus infection involves a piece of host cell membrane ending up around the capsid?
Release
142
What are the two methods of virus release?
Release by budding or release by lysis
143
What does erythromycin target?
Bacterial ribosomes
144
What does penicillin target?
Growing bacterial cell wall
145
What are 5 possible sites for antiviral drugs?
```
Viral nucleic acid polymerases
Viral enzymes involved in protein syntehsis (integrase, protease)
Uncoating
Attachment/entry
Release
```
146
What 2 characteristics does double stranded RNA have?
Potenet inducer of interferon
| Ligand for Toll-Like receptor 3
147
Name two viruses that can reactivate?
Herpes simplex virus
| Varicella-zoster virus
148
What two current methods are there for virus detection?
PCR
| Antigen detection
149
What is the difference between bactericidal and bacteriostatic?
Bactericidal kill bacteria and bacteriostatic inhibit bacterial growth
150
Name 3 antibiotic groups that act on the bacterial cell wall?
1. Penicillins (penicillin, flucloxacillin, amoxicillin, temocillin, co-amoxiclav and piperacillin/tazobactam)
2. Cephalosporins - ceftriazone
3. Glycopeptides - vancomycin, teicoplanin
151
How do the penicillins inhibit cell wall synthesis?
By preventing the cross-linking of peptidoglycan subunits, bactericidal
152
What are the penicillins excreted via?
The kidneys
153
What are the three forms of pemnicillin available?
Benzylpenicillin
Phenoxymethyl penicillin
Benzathine penicillin
154
What penicillin is used for Gram positive organisms?
Flucloxacillin (IV, oral)
155
What three penicillins are used for treating Gram positive and Gram negative organisms?
1. Amoxicillin (IV, oral)
2. Co-amoxiclav - amoxicillin plus clavulanic acid (IV, oral)
3. Piperacillin/tazobactam (IV only)
156
What penicillins are used to treat Gram negative organisms?
Temocillin (IV only)
157
What antibiotic is used for cellulitis?
Flucloxacillin
158
What penicillin is only active against coliforms?
Temocillin (IV)
159
What group of antibiotics inhibit cell wall synthesis and are bactericidal?
The cephalosporins
160
How are cephalosporins exrcreted?
Via the kidneys and urine
161
What spectrum of antibiotics are cephalosporins?
Broad spectrum
162
Name two glycopeptides and how are they administered?
1. Vancomycin (IV)
| 2. Teicoplanin (IV)
163
Which antibiotic bidns to the end of the growing pentapeptide chain during peptidoglycan synthesis, preventing cross-linking and weakening the bacterial cell wall?
Vancomycin
164
How are glycopeptides excreted?
Via the kidneys and urine
165
What type of cell wall are glycopeptides only active against?
Gram positive cell wall
166
Name 3 groups of antibiotics that inhibit protein synthesis?
Macrolides
Tetracyclines
Aminoglycosides
167
Name three macrolides?
Erythromycin, clarithromycin and azithromycin
168
Name a tetracycline?
Deoxycycline
169
Name an aminoglycoside?
Gentamicin
170
What can be said about macrolides and tetracyclines in the way protein synthesis can resume when they are removed?
Bacteriostatic
171
How are macrolides excreted?
Via the liver, biliary tract and into the gut
172
How must gentamicin be given?
Intravenously
173
Is gentamicin bactericidal?
Yes
174
How is gentamicin excreted?
Via the urine
175
What can gentamicin cause damage to?
The kidneys and 8th cranial nerve (deafness and dizziness)
176
Which three groups of antibiotics act on bacterial DNA?
Metronidazole
Trimethoprim (+/- sulphonamide)
Fluoroquinolones
177
How does metronidazole act?
By causing strand breakage of bacterial DNA
178
What antibiotic is used to treat true anaerobic infections?
Metronidazole
179
Which antibiotics mode of action is to inhibit bacterial folic acid synthesis?
Trimethoprim (oral)
180
What can trimethoprim be given in combination with?
Sulphamethoxazole (orally or IV) as co-trimoxazole
181
How is trimethoprim excreted?
Via the urine
182
Name two fluoroquinolones
1. Ciprofloxacin (IV, oral)
| 2. Levofloxacin (IV)
183
What antibiotics act by preventing "supercoiling" of bacterial DNA?
Fluoroquinolones
184
How are fluoroquinolones excreted?
via the urine
185
Which 4 antibiotics do we try to avoid due to C.diff?
Cephalosporins
Co-amoxiclav
Ciprofloxacin
Clindamycin
