Microbiology Flashcards
(142 cards)
1
Q
What are the 5 main groups of human pathogens?`
A
Bacteria, fungi, protozoa, prions, viruses
2
Q
What are pathogens which are eukaryotic, single celled animals which are generally hard to treat?
A
Protozoa
3
Q
What are fungi?
A
Higher, plant like organisms, eukaryotes
4
Q
What are bacteria?
A
Generally small, single celled organisms, prokaryotes
5
Q
What are very small, obligate parasites which are non-living?
A
Viruses
6
Q
What are non-living proteins that cause infection?
A
Prions
7
Q
Which are bigger, eukaryotes or prokaryotes?
A
Eukaryotes
8
Q
Which are usually multicellular, eukaryotes or prokaryotes?
A
Eukaryotes
9
Q
What is the chromosome organisation in eukaryotes?
A
Linear chromosomes and histones
10
Q
What is the chromosome organisation in prokaryotes?
A
Single circular chromosomes
11
Q
What, with regards to gene structure, do eukaryotes possess that prokaryotes don’t?
A
Introns
12
Q
What is of importance about the cell membrane in prokaryotes?
A
It is the only membrane a prokaryote contains
13
Q
What do some, but not all, prokaryotes possess to aid movement?
A
Flagellum
14
Q
Apart from a flagellum, what else do some prokaryotes have and others don’t?
A
External capsule
15
Q
What is contained in the nucleoid of prokaryotes?
A
DNA and proteins
16
Q
What does the prokaryotic nucleoid not have?
A
A membrane
17
Q
What does DNA replication occur via in prokaryotes?
A
DNA dependent RNA polymerase
18
Q
What are transcription and translation in prokaryotes?
A
Co-ordinated
19
Q
What is an example of an extra chromosomal replicon which can also exist in prokaryotes?
A
Plasmid
20
Q
What is released in the cytoplasmic membrane of prokaryotes?
A
Electrons
21
Q
What is found across the membrane of prokaryotes?
A
+ charge and a proton gradient
22
Q
Where do processes which would normally occur elsewhere (such as the mitochondria) occur in prokaryotes?
A
Cytoplasmic membrane
23
Q
What is the structure of the prokaryotic cell wall?
A
Rigid, repeated polysaccharide structure
24
Q
What is the gram + cell wall?
A
Thick, multi layer of peptidoglycan
25
What is the gram - cell wall?
Formed of an outer membrane, periplasm and thin single layer of peptidoglycan
26
What is the main component of the outer layer of the gram - cell wall?
Lipopolysaccharide
27
What are the fimbriae/pilus which are found on the outer surface of bacteria sometimes?
Hair like appendages, similar to cilia
28
Where does protein synthesis occur in prokaryotes?
Plasma membrane
29
Describe the run of prokaryotic protein synthesis?
Gene, mRNA, tRNA, protein, 2nd, 3rd, 4th structure, export, assembly, processing
30
Where occurs between the gene and mRNA stages of protein synthesis in prokaryotes?
Transcription
31
What occurs between the tRNA and protein stages of protein synthesis in prokaryotes?
Translation
32
What factors are required for prokaryotic growth?
Food, temperature, pH, osmotic protection, oxygen
33
What are food sources for prokaryotes?
C, H, O, N, vitamins, trace elements
34
What are mesophiles?
Body temperature orientated bacteria
35
What is the optimum pH range for bacteria which infect humans?
6.8-7.2
36
What is the optimum osmotic protection for bacteria which infect humans?
0.85% NaCl
37
What are microaerophiles?
Need oxygen for respiration but are killed at high concentrations
38
What are facultative anaerobes?
Can go with or without oxygen
39
What are obligate anaerobes?
Get killed at even low oxygen concentrations
40
What can microorganisms be classified depending on?
Appearance/structure, growth requirements, enzyme/molecular/metabolic tests
41
What is an example of a cocci that can divide in 1 plane to produce 2 cocci?
Diplococcus
42
What is an example of a cocci that can divide in 1 plane to form a chain of 4-20 cocci?
Streptococcus
43
What is an example of a cocci that can divide in 3 planes to produce a clump of cocci?
Staphylococcus
44
What are examples of different types of bacilli?
Generally rod shaped, can be chains, spirals (rigid or flexible) or curved
45
What gram are curved bacilli?
Negative
46
What media is used for gram staining?
Eosin and methylene blue
47
What colour is gram negative bacteria on a gram stain?
Pink
48
What colour is gram positive bacteria on a gram stain?
Purple
49
What are examples of diseases which have bacteria that do not gram stain well?
TB and syphilis
50
What is aerobic bacteria?
Grow in oxygen
51
What are obligate anaerobes?
Killed by oxygen
52
What are obligate aerobes?
Require oxygen
53
What are facultative anaerobes?
Tolerate oxygen
54
What bacteria is identified by haemolysis?
Streptococcus
55
What does alpha haemolysis show?
A green colour, partial haemolysis
56
What are examples of alpha haemolytic strep?
Strep pneumoniae and viridans
57
What does beta haemolytic strep show?
A clear colour, complete haemolysis
58
What is an example of group A beta haemolytic strep?
Strep. pyogenes
59
What is an example of group B beta haemolytic strep?
Strep. agalactiae
60
What does gamma haemolysis show?
No haemolysis
61
What is an example of gamma haemolytic strep?
Enterococcus
62
What is MALDI-TOF?
A powerful, rapid, precise and cost effective test for bacteria
63
What is MALDI-TOF not so good for?
Strep and staph
64
What is virulence?
The capacity of a microbe to damage a host
65
What is an endogenous microorganism?
Bacterial flora within a closed space
66
What is an exogenous microorganism?
Not normal flora
67
What is commensal bacteria?
An endogenous organism with a mutualistic effect
68
What is an opportunistic pathogen?
One which causes infection when opportunity or a change in natural immunity arises
69
What is aspergillus.spp?
A fungal infection which occurs in immunocompromised
70
What is candida.spp?
A fungus from a skin infection
71
What are some examples of protozoan infections in man?
Malaria/toxoplasma/some GI infections
72
What are some common gram -'s?
Klebsiella, enterobacter.spp, salmonella.spp, haemophilus. spp, bacteroides
73
What are some common gram +'s?
Streptococcus.spp, staphylococcus.spp, enterococcus.spp, clostridium
74
What are E.coli, Klebsiella, Enterobacter, Proteus?
Common gut commensals
75
What are salmonella, shigella, verotoxin?
Significant gut pathogens
76
What are coliforms?
A species of gram - bacilli which look like E-coli
77
How do coliforms grow best?
Aerobically
78
What happens when a coliform gets into a usually sterile site?
It will cause serious infection
79
What are examples of infections caused by coliforms?
UTI, peritonitis, biliary tract infection
80
How are coliform infections best treated?
Gentamicin
81
What does the outer membrane of gram - bacteria bind to?
Macrophages, B cells and more
82
What does gram - bacteria binding to inflammatory cells do?
Stimulates release of acute phase cytokines
83
What does the release of acute phase cytokines cause?
Endotoxin shock, systemic inflammatory response syndrome
84
What molecule increases the body's thermal set point to cause fever?
Prostaglandin E
85
What is fever defined as?
Greater than 38 degrees
86
What are examples of strict aerobic gram - bacilli?
pseudomonas aurigunosa, legionella pneumophilia
87
What are vibrio cholerae, campylobacter. spp, helicobacter. pylori?
Spiral/curved gram - bacilli
88
What is a small gram - cocco bacillus?
Haemophilus influenzae
89
What is strep. pneumoniae?
Gram + alpha haemolytic cocci
90
What gram stain is staph aureus?
Positive
91
What gram stain is staph epidermis?
Negative
92
What is staph epidermis associated with?
Foreign devices e.g. catheter
93
What is clostridium spp?
Gram + anaerobic bacilli
94
What does clostridium produce and what does this cause?
Endotoxins which cause severe tissue damage
95
What in terms of nucleic acid do viruses possess?
DNA or RNA but never both
96
What surrounds the protein coat in some viruses and where does this come from?
Envelope- derived from the host cell
97
What does icosahedral symmetry mean?
A virus is made up of repeated subunits- they are full of lots of information but few genes
98
What does helical symmetry mean?
Made up of a single repeated unit so it only has to code for 1 protein
99
What are the 6 steps of virus infection?
Attachment, entry, uncoating, protein synthesis, assembly, release
100
How can viruses enter cells?
Through the envelope fusing with the cell membrane or endocytosis in viruses without an envelope
101
The action of what aids uncoating of viruses?
Viral ion pumps
102
What are antimicrobials?
Drugs used to treat all types of infection, not just bacteria
103
What will recognise proteins on the viral cell surface and signal the infected cell to commit suicide to prevent spread of the virus?
Cytotoxic T cells
104
What prevents viruses binding to more cellular receptors?
Neutralising antibodies
105
What are examples of viruses which can reactivate?
Varicella Zoster or Herpes simplex virus
106
What are examples of chronic viral infections which remain inactive for years?
HIV/Hepatitis C
107
What will previous viral infections show that new ones won't?
IgG antibodies from immunological memory
108
What are current viral detection agents?
PCR, antigen detection
109
What are the 3 main ways that viruses exert pathogenesis?
Lysis or hijacking of cell material, cell proliferation or through cytotoxic T cells
110
What do bacteriostatic antibiotics do?
Inhibit growth of bacteria
111
What do bacteriocidal antibiotics do?
Kill bacteria
112
How can antibiotics be excreted?
Either in the urine or through the liver, biliary tract and faeces
113
What is the advantage of using IV antibiotics over oral?
They will reach peak serum levels quicker
114
What are some targets of antibiotics?
Cell wall, ribosomes, DNA replication, DNA gyrases, metabolic pathways, cell membrane function
115
What type of antibiotics target the cell wall?
Beta-lactams and glycopeptide antibiotics
116
What are examples of beta-lactam antibiotics?
Penicillin, amoxicillin, flucloxacillin, co-amoxiclav, ceftriaxone, carbapenems
117
What is an example of a glycopeptide antibiotic?
Vancomycin
118
What does vancomycin have no activity against?
Gram -
119
What is a penicillin targeting gram +?
Flucloxacillin
120
What are penicillins targeting gram + and -?
Amoxicillin, co-amoxiclav, tazocin
121
What is a penicillin targeting gram -?
Temocillin
122
How are penicillins excreted?
Via kidneys
123
Are penicillins safe in pregnancy?
Yes
124
What is flucloxacillin used for?
Staph and strep only
125
Why is the use of cephalosporins limited?
They kill normal gut flora and can cause gastroenteritis
126
What are examples of antibiotics which target protein synthesis?
Aminoglycosides e.g. gentamicin and tetracyclines e.g. doxycyline
127
When should you not use doxycycline?
Infants, children and pregnancy
128
What are examples of macrolide antibiotics?
Erythromycin, clarithromycin
129
How are macrolides excreted?
In the liver
130
Where do antibiotics such as metronidazole, fluoroquinones and rifampicin target?
Nucleic acid synthesis
131
What are common side effects of all antibiotics?
Nausea, vomiting, diarrhoea- may also affect absorption of oral contraceptives
132
What are side effects of gentamycin?
Renal and CNVIII damage
133
What is an effect of metronidazole?
Interacts with alcohol
134
What do broad spectrum antibiotics increase the risk of?
C. diff infections, especially in the elderly
135
What are 3 reasons for antibiotics being given in combination?
- Cover a wide range of organisms
- Prevent development of resistance
- Create a synergistic effect
136
What antibiotics should never be given in combination?
A bacteriostatic and bacteriocidal antibiotic
137
What are the '4C' antibiotics which should be avoided?
Cephalosporins, co-amoxiclav, ciprofloxacin, clindamycin
138
What are some examples of natural resistance?
Target not present or accessible, developmental structure, metabolism
139
What are biofilms?
Organisms behaving as part of a multi-cellular community
140
What is resistance?
Drug is no longer active against an entire population of cells
141
What can resistance occur because of?
Mutation, selection pressure and evolution, horizontal gene transfer
142
What is the difference between cross resistance and multiple resistance?
Cross resistance means that resistance came about through a single mechanism and multiple resistance means it took many
