Microbiology Flashcards
(94 cards)
1
Q
Where do antibiotics target?
A
Cell wall Ribosomes DNA replication DNA gyrases Metabolic pathways
2
Q
What are the two types of bacteria and how are they different?
A
Gram positive - has a double layered cell wall
Gram negative - has a single layered cell wall
3
Q
Which antibiotics act on the cell wall?
A
Penicillins
Cephalosporins
Glycopeptides
4
Q
How do penicillins and cephalosporins (beta-lactams) work?
A
They are bacteriocidal and blocks synthesis of the cell wall
5
Q
What are the types of penicillins and what type of bacteria do they act on (+ve or -ve)?
A
Flucloxacillin - Gm +ve Amoxicillin - Gm +ve and -ve Co-amoxiclav - Gm +ve and -ve Temocillin - Gm-ve (Piperacillin/tazobactam) - Gm +ve and -ve
6
Q
What are the 4 C’s you should avoid using?
A
Cephalosporins
Co-amoxiclav
Ciprofloxacin
Clindamycin
7
Q
Why should you avoid using the 4 C’s?
A
They are broad spectrum antibiotics so have a higher risk of c. Difficile infection
8
Q
Protozoa is a eukaryote. True or false?
A
True
9
Q
What type of microorganism can undergo haemolysis?
A
Streptococci
10
Q
What are some microbiological tests?
A
Blood culture Urine culture Faeces culture Swab of pus PCR
11
Q
What does exogenous microorganisms mean?
A
Not normal flora
12
Q
What does virulence mean?
A
The ability of a microbe to cause damage to a host
13
Q
What is a pathogen?
A
A harmful organism producing a pathology
14
Q
Commensal bacteria is part of your normal flora, ture or false?
A
True
15
Q
Where would an opportunistic pathogen be found?
A
In an immunocompromised patient
16
Q
Give examples of some gram negative bacteria.
A
Neisseria
Escherichia
Salmonella
Shigella
17
Q
Give examples of gram positive bacteria.
A
Streptococcus
Staphylococcus
Enterococcus
18
Q
Give examples of fungi
A
Candida spp. (Yeast)
Aspergillus (mould)
19
Q
Give examples of protozoa
A
Malaria
Toxoplasma
20
Q
How do viruses work?
A
Attach Enter (non-enveloped enter via endocytosis, enveloped ones fuse their membrane and the cells membrane) Uncoat Nucleic acid and protein synthesis Assembly Release (exocytosis)
21
Q
What is a coliform?
A
Species of GM-ve bacilli that look like Escherichia coli on gram film and when cultured on blood agar
Note many are part of normal gut flora
22
Q
What is the first line antibiotic used to treat coliform infections?
A
Gentamicin
23
Q
Why is haemolysis of streptococci used?
A
To help classify the streptococci
24
Q
What happens in alpha-haemolysis?
A
Partial haemolysis- causes a greenish decolourisation around the colony
25
What happens in beta-haemolysis?
Complete haemolysis - there is a complete clearing around the colony (looks like its glowing)
26
What happens in gamma-haemolysis?
No haemolysis
27
What are the most pathogenic streptococci?
Beta-haemolytic group A
28
What causes scarlet fever?
Streptococci in group A
29
Enterococci is non-haemolytic, true or false?
True
30
Give examples of staphylococcus bacterium.
S. Aureus (+ve)
| S. Epidermidis (-ve)
31
What does neisseria spp cause?
STD/STI
| Meningitis
32
Where does escherichia coli effect?
GI tract
33
What are the 5 i's of infection?
```
Inhalation
Ingestion
Inoculation
Mother to infant
Intercourse
```
34
What genus does a gram positive sample belong to if it is cocci in clusters?
Staphylococcus
35
What is haemolysis?
The ability of the bacterium to break down the red blood cells
36
How can you physically tell the difference between streptococci and staphylococcus?
Streptococci = chains
Staphylococcus = clusters
37
What does MRSA stand for?
Methicillin resistant staph aureus
38
What categaries does streptococci subdivide into?
Alpha beta and gamma haemolytics
39
What bacteria is alpha haemolytic?
Strep. Pneumoniae
| Strep. Viridans
40
What bacteria is beta haemolytic?
Group A strep. (Strep pyogens)
| Group B strep (neonatal meningitis)
41
What does non-haemolytic bacteria called?
Enterococcus sp.
42
What is c. Difficile?
Anaerobic bacilli
43
Are coliforms gram positive or negative?
Gram negative
44
What is virulence?
degree of pathogenicity (ability of pathogen to cause disease) of an organism
45
what are the 3 types of atmostphere that bacteria can grow in?
Aerobic
Microaerophilic (reduced O2 and more CO2)
Anaerobic
46
What type of bacteria release exotoxins?
Gram positive
47
what type of bacteria release endotoxin?
Gram negative
48
what is an exotoxin?
Toxin produced inside gram positive bacterial cells that is exported out
49
what is an endotoxin?
Toxin found in gram negative bacterial cell wall.
50
Give examples of fungi.
Mould (aspergillus)
| Yeasts (candida)
51
what are the different types of gram positive cocci?
Streptococcus
Enterococcus
Staphylococcus
52
how do you differentiate between staphylococcus?
coagulase test
53
How do you distinguish between streptococcus and enterococcus and why?
Haemolysis as strep will either be alpha or beta, enterococcus will be gamma
54
if gram positive cocci are found in clusters what does this suggest?
Staphylococcus
55
How do you identify staph aureus?
Gram positive cocci, in cluster, that is coagulase positive, appearing golden
56
what is the antibiotic of choice to treat staph aureus infection?
Flucloxacillin
57
what would coagulase negative staphylococcus suggest (including common cause of infection), and what is this?
Staph epidermidis
| normal skin commensal, can be found in IV line infections
58
why does the immune system give rise to fever?
Growth of pathogens is slow if temp increases
59
How are gram negative cocci orientated?
Diplococci
60
Give examples of gram negative cocci bacterium (2)
Neisseria gonorrhoea
| Nisseria meningitidis
61
What are coliforms?
Gram negative bacilli
| which can be aerobic or anaerobic
62
Give examples of coliforms both commensals and pathogens.
```
Gut commensals:
- E coli
- Klebsiella
- Proteus
Gut pahtogens:
- Salmonella
- Shigella
- E coli 0157
```
63
give examples of strict aerobes.
Gram negative bacilli:
pseudomonas aeruginosa
Legionella pneumophilia
64
What type of bacterium is campylobacter and what does it cause?
Spiral or curved gram negative bacilli causing food poisoning
65
what group of bacterium is haemophilus influenzae caused by?
small gram negative bacillus
66
what is clostridium spp. and where is it normally found
gram positive anaerobic bacilli that is part of normal bowel flora
67
what is the first line antibiotic used to treat coliforms?
Gentamicin
68
what is the first line treatment for infections caused by anaerobes?
metronidazole
69
what type of bacteria is TB
Microbacteria characterised by thick waxy outer coat
70
what are the different ways of bacterial gene transfer and how do they work?
Transformation (DNA from dead bacteria taken up)
Conjugation (fimbria to transfer plasmid DNA - sex)
Transduction (viruses infecting bacteria can transfer from one to the other)
71
give an example of a narrow and broad spectrum antibiotic.
```
Narrow = penicillin
Broad = tetracycline
```
72
what type of cell wall do gram positive organisms have?
Thick layer of peptidoglycan and single phospholipid bilayer
73
What type of cell wall do gram negative organisms have?
Thin layer of peptidoglycan and two phospholipid bilayers
74
why are cephalosporins limited to hospital?
May induce clostridium difficile infection
75
what type of antibiotic is vancomycin and what does it act on?
Glycopeptide which acts on gram positive cell walls
76
which groups of antibiotics inhibit protein synthesis?
Macrolides
Tetracyclines
Aminoglycosides
77
What group is erthromycin in?
Macrolides
78
Give an example of a tetracycline.
doxycycline
79
What group is gentamicin in?
Aminoglycosides
80
How do macrolides and tetracyclines work?
Bacteriostatic attaching to bacterial ribosomes to prevent protein synthesis
81
How do aminoglycerides work?
Bactericidal binding to ribosomes so kill that protein.
82
what are the side effects of gentamicin?
Kidney damage
| Damage of CN VIII resulting in deafness and dizziness
83
which antibiotics act on bacterial DNA?
Metronidazole
Trimethoprim
Fluoroquinolones
84
How does metronidazole work and what is it used to treat?
Causes strand breakage of bacterial DNA
| Treats true anaerobic infections
85
How does trimethoprim work and what does it treat?
Inhibits bacterial folic acid synthesis
| Works against gram positivie and negative bacteria
86
Give examples of fluoroquinolones.
Ciprofloxacin, levofloxacin
87
how do fluoroquinolones work?
Bactericidal and prevent supercoiling of bacterial DNA
88
why should you avoid broad spectrum antibiotics?
increase risk of C. difficile
89
which antibiotics should you avoid in pregnancy?
Gentamicin, tetracycline, fluoroquinolones (avoid trimethoprim and metronidazole in first 3 months)
90
how do viruses replicate?
Attachment
Entry
Uncoating
Nucleic acid and protein synthesis (using host ribosomes)
Assembly
Release (budding - released in envelope - or lysis - cell burst, and virus escapes)
91
which antibodies neutralise viruses and how do they do this?
IgG and IgM, prevent virus binding to cellular receptors
92
how do you detect viruses clinically?
PCR and antigen detection
93
which groups of antibiotics act by inhibiting protein synthesis?
macrolides, aminoglycerides, clindamycin, tetracylines
94
which groups of antibiotics act on bacterial DNA?
metronidazole, trimethoprim/co-trimoxazole, fluroquinolones
