Microbiology Flashcards
(96 cards)
1
Q
name infectious agents
A
parasites fungi bacteria viruses prion proteins
2
Q
single cell parasites
A
protozoa
3
Q
flagella
A
tall bacterial structures
4
Q
pili
A
adhesion coccus bacteria
5
Q
Bacillus
A
rod shaped bacteria
6
Q
spirochaetes
A
spiral shaped bacteria
7
Q
what are prion proteins
A
infectious proteins that have no DNA or RNA and cannot be removed by sterilisation or disinfectant
8
Q
gram +ve stains
A
purple
9
Q
gram -ve stains
A
pink
10
Q
pathogen
A
harmful organism
11
Q
commensal
A
organism that is part of a normal flora
12
Q
opporunistic pathogen
A
probably only cuase infection in immunocomprimised patients
13
Q
contaminant
A
organism that has got into a culture by accident
14
Q
pathogenicity
A
ability of a microorganism to produce a disease
15
Q
virulence
A
degree of pathogenicity of an organism
16
Q
how does bacterial replicate
A
via binary fission
17
Q
what does bacteria need to grow
A
correct temp
correct pH
food
moisture
18
Q
4 phases of bacterial growth
A
lag phase
log phase
stationary phase
death phase
19
Q
What are exotoxins
A
usually gram positive bacteria- produced inside a cell and exported from it
20
Q
what are endotoxins
A
usually gram negative bacteria-part of gram neg bacterial cell wall
21
Q
what are the functions of toxins
A
- cause release of cytokines from immune cells
- cause damage to red and white blood cells and make blood vessels leaky- reduced clotting ability, BP resulting in sepsis
22
Q
what is sepsis
A
causes leaky blood vessels (poor tissue perfusion) and activated clotting systems (increasing risk of haemorrhage) gram -ve sepsis worse than gram +ve
23
Q
moulds
A
produce spores (spreads in air) and hyphae (invades organ tissues)- does not gram stain
24
Q
Aspergilus
A
usually targets immunocompromised patients
25
yeast
single cells that reproduce by budding
| gram stain= large gram +ve oval
26
Gram +ve
purple stain= thick layer of peptoglycan and then just deep to that have a cytoplasmic membrane made of phospholipids
27
Gram -ve
pink stain= outer cytoplasmic mambrane, a middle thin layer of peptidoglycan and an inner cytoplasmic membrane
28
diagnostic methods for bacteria
- microscophy (gram film)
- culture
- antigen detenction (urine)
- serology (antibody detection in blood)
- PCR
29
Streptococcus
Gram positive cocci
aerobic
cocci chains
30
Alpha haemolysis (partial)
strep pnuemoniae and strep virdans
31
Beta haemolysis (complete)
group strep A (throat and skin infection )
| group strep B (neonatal meningitis)
32
most pathogenic strep
strep pyrongenes (sore throat, skin and soft tissue infections and puerperal sepsis) severe life threatening in pregnant ladies
33
gamma haemolysis
none
34
Enterococcus
```
Gram positive cocci
aerobic
non-haemolytic
normal gut commensal and cause of UTIs
VRE- antibiotic resistant strains of E.faecium is v bad in hospitals
```
35
Staphylococcus
Gram positive cocci
| cocci clusters
36
Staph aureus
```
coagulase positive (golden)
wound and skin infections
Tx: flucoxacillin
common cause of bacteraemia (bacterial in blood)
IV drug users
toxic shock syndrome
```
37
Staph epidermis
Coagulase negative (white)
IV line infection
produces a surface slime to allow them to stick to plastic and other artificial things in the body
prosthetic heart valve or joint
38
Panton-valentine leucocidin
toxin of staph aureus that can damage white blood cells
39
MSSA
METHICILLIN SENSITIVE STAPH AUREUS
40
Fever cascade
antigen attacks macrophage
releases cytokines
travel to anterior hypothalamus of brain
stimulates production of prostiglandin E
resets bodys thermostat
body percieves its cold so shivers to conserve heat
Fever- growth of pathogens slow if temp increases
41
Fever cascade
antigen attacks macrophage
releases cytokines
travel to anterior hypothalamus of brain
stimulates production of prostiglandin E
resets bodys thermostat
body percieves its cold so shivers to conserve heat
Fever- growth of pathogens slow if temp increases
42
Gram negative cocci
- diplococci
- aerobic
- gonorrhoea
- bacterial meningitis
43
Coliforms
- gram neg bacilli
| - aerobic but can be anerobic
44
how can you differentiate coliforms?
1. biochem reactions
| 2. antigenic structures (either o antigen on cell wall or H antigen on flagella)
45
gut commensals
e.coli, klebsiella, proteus, enterobacter spp
46
gut pathogens
salmonella, shigella, e.cole 0157
47
Strict anerobes
gram neg bacilli
pseudomonoas aeruginosa
legionella pneumophilia
48
curved gram neg bacilli
campylobacter
| h.pylori
49
Haemophilus influenzae
small gram neg bacillis, common cause of chest infection esp COPD exacerbation
50
Gram positive anaerobic bacilli
Clostridium spp- antibiotic assoc diarrhoea
part of normal bowel flora
produces spores
produces exotoxin- that causes severe tissue damage
51
clostridium perfringens
a severe soft tissue tissue infection following contamination of a wound
52
clostridium tetani
tetnus- a fatal paralytic illness
53
Gram neg anaerobic bacilli
bacteroides spp
normal gut commensals, only pathogenic when found in other sides
Tx: metronidazole
54
Mycobacteria
thick waxy outer coat
Ix: acid fast bacilli or ziehl neelson stain
TB
55
Stages of gene transfer
1. transformation
2. conjugation
3. transduction
56
what is transformation
DNA from dead bacteria is taken up by the living bacteria and incorporated in plasmids or the bacterial chromosome
57
what is conjugation
sex pilus produced by one bacterial through which plasmid DNA can be transferred
58
what is transduction
viruses infecting bacteria can transfer bits of DNA from one bacterium to another
59
5 I's of infection
```
Inhalation
Ingestion
Inoculation
Mother to Infant
Intercourse
```
60
Chain of infection
infectious microbe-->reservoir--> portal of exit-->modes of transmission-->portal of entry--> suceptable host (circle and key is to break chain)
61
when should you wash hands
```
before patient contact
before aeseptic task
after fluid exposure
after patient contat
after contact with patient surroundings
```
62
antibiotics
drugs that are used to treat or prevent infection caused by microorganisms
63
Bactericial
kill bacteria
64
Bacteriostatic
inihibit bacterial growth
65
narrow spec Abx
penicillin
66
Broad spec Abx
tetracycline
67
antibiotic resistance
1. production of enzymes that destory ABX
2. altered Abx binding sites
3. alteration of cell wall porins
4. up-regulating of efflux pumps
68
Antibiotics that work on cell wall;
penicillin
cephalosporins (ceftriaxone)
glycopeptides (vancomycin)
69
Gram positive
thick layer of peptidoglycan and a single phospholipid bilayer
70
Gram negative
thin layer of peptidoglycan and a double phospholipid bilayer
71
Penicillin
```
inhibit cell wall synthesis by preventing cross linking of peptidoglycan subunits
beta-lactam Abx
Excreted rapidly via kidneys
type 1 hypersensitivity
eg flucoxacillin, amoxicillin
```
72
Amoxicillin
gram +ve and -ve
| co-amoxiclav= amoxicillin and clavulanic acid (inhibits the action of beta lactamase enzyme)
73
Cephalosporins
```
inhibit cell wall synthesis
bactericidal
beta-lactam abx
may induce C.diff
excreted by kidneys
```
74
Glycopeptides
gram positive effect
cell wall antibiotics
binds to end of growing chain and prevents cross linking and weakens bacterial cell wall
bacericidal
only effective agains gram +ve cell walls
EG VANCOMYCIN
75
Glycopeptides
gram positive effect
cell wall antibiotics
binds to end of growing chain and prevents cross linking and weakens bacterial cell wall
bacericidal
only effective agains gram +ve cell walls
EG VANCOMYCIN
76
Abx that inhibit protein synthesis
macrolides (erythromycin, clarithromycin and azithromycin) BACTERIOSTATIC
tetracyclines (doxacycline and minocycline) BACTERIOSTATIC
aminoglycosides (gentamicin) BACTERICIDAL
77
Macrolides
Lipophilic and pass through cell membranes easily (useful for infections where the bacteria 'hides' from the hosts immune system)
- excreted via biliary tract
78
Tetracycline
Doxycycline (IV, sometimes IM)
- Broad spectrum, can destruct intestinal flora (so increased secondary infections)
- can permanently stain teeth of children <12 years
79
Aminoglycosides
EG. Gentamicin
-Inhibit protein synthesis but are bactericidal
-Mainly active against gram negative aerobic organisms
E.g. coliforms and pseudomonas aeruginosa
-Toxicity - kidney damage and damage of CN VIII - vestibulocochlear (deafness and dizziness)
-Excreted in the urine
80
Abx that act on bacterial DNA
- Metronidazole
- Trimethoprim
- Fluoroquinolones
81
Metronidazole
- Causes strand breakage of bacterial DNA
- Treat true anaerobic infections
- Interacts with alcohol
82
Trimethoprim
- Inhibits bacterial folic acid synthesis
- Some activity against some gram negative and some gram positive
- Exceted in urine
83
Fluoroquinolones
- Ciprofloxacin, Levofloxacin
- Prevent supercoiling of bacterial DNA
- Bactericidal
- Restricted use in order to prevent Clostridium difficile
- Weakens tendons, causes seizures
- Excreted in urine
84
Side effects of ABX
Gentamicin (renal and VIII nerve damage)
Ciprofloxacin (tendonitis)
Metronidazole (interacts with alcohol)
Broad spectrum Abs increase risk of C.Diff (avoid 4 Cs)
85
Abx to avoid in pregnancy
Trimethoprim + Metronidazole in first 3 months
| Gentamicin, tetracycline and Fluoroquinolones avoided all together
86
Abx to avoid in pregnancy
Trimethoprim + Metronidazole in first 3 months
| Gentamicin, tetracycline and Fluoroquinolones avoided all together
87
Lantency
virus that can become inactive then reactivate later
| EG. Varicella-zoster virus remains latent in the dorsal root ganglia before becoming reactivated (shingles)
88
viral replication
1) Attachment
Interact with specific receptors in target cell, ligand > receptor
2)Entry
Endocytosis (non-enveloped viruses)
3)Uncoating
Viral nucleic acid released from capsid
4) Nucleic acid and protein synthesis
Host ribosomes used, host polymerases may be used also
5)Assembly
Nucleic acid and proteins packaged together
6)Release
-Budding(Virus released with envelope derived from host cell membrane) Doesn't kill cell
-Lysis (Viruses accumulate until cell bursts)Kills cell
89
signs of recent infection
- detection of virus specific IgM antibodies
| - detection of rising titre volume of virus sepcific IgG antibodies
90
immunity and virus infection
- Cytotoxic T lymphocytes - recognise proteins on cell surface as being foreign and will signal infected cell to commit suicide in order to prevent formation of new viruses
- Neutralising antibodies - IgG, IgM - prevent virus binding to cellular receptors
- Hep B and C have a role to play in primary hepatocellular carcinoma
91
Virus detection
PCR and antigen detection
92
Serology
antigen etection in blood
93
PCR
detects DNA or RNA and replicates it millions of times
94
Anthrax
disease of cows and sheep
95
enterotoxins
toxins that act in the gut- food poisoning
96
4 C's
cephalosporins
co-amoxiclav
ciprofloxacin
clindamycin
