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PRINCIPLES > Microbiology > Flashcards

Microbiology Flashcards

1
Q

What are the three classifications of life?

A

Eubacteria, archaea, eukaryotes

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2
Q

Which classifications of life do bacteria, viruses, fungi, and protozoa fall into?

A

Eubacteria, archaea, eukaryotes x2

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3
Q

Which two external structures are present only in bacteria and what are their purposes?

A

Fimbrae - attachment, flagella - movement

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4
Q

Describe the storage of genetic information in the bacteria.

A

One large bacterial chromosome, several smaller plasmids

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5
Q

What is the ideal pH growth range for bacteria?

A

6.8 - 7.2

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6
Q

Osmotic protection - what is the ideal concentration of NaCl for growth of bacteria?

A

0.85%

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7
Q

What are the four phases of bacterial growth?

A

Lag, exponential, stationary, decline

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8
Q

What is a biofilm?

A

A community of bacteria that has a more sophisticated culture

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9
Q

Which aspect of bacteria form biofilms?

A

Pillae

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10
Q

What is the difference between aerobic and anaerobic bacteria (except that one uses oxygen)?

A

Electron acceptors - aerobic use oxygen, anaerobic use e.g. nitrogen

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11
Q

Define facultative and capnophilic bacteria types.

A

Tolerates O2, prefers CO2

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12
Q

What are the three main shapes of bacteria?

A

Cocci (spheres), bacilli (rods), spirillum/spirochete/fusiform (spiral shaped)

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13
Q

Describe what can be ascertained from the results of a gram stain test, and how.

A

The gram stain type - piNk is negative, purPle is positive

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14
Q

Which pathogen is tested for using haemolysis?

A

Streptococcus

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15
Q

What are the three types of haemolysis and what do they show?

A

Alpha - greening, beta - yellow halo, gamma - N/A

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16
Q

Which Lancefield groups of streptococcus are shown by haemolysis?

A

Alpha - D, Beta - A, B, C, F, G

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17
Q

What is the coagulase test? Which bacteria tests positive?

A

Tests for the presence of the enzyme coagulase - staph aureus

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18
Q

What is the catalase test? Which bacteria tests positive?

A

Tests for the enzyme catalase, which breaks down H2O2. Staphylococcus

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19
Q

What is the Ziehl Neelsen stain used for, and which pathogen in particular shows +ve?

A

Seperates acid fast from acid slow. Mycobacterium tuberculosis.

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20
Q

What is selective media?

A

Allows the growth of one bacteria over another.

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21
Q

What is differential media?

A

Visible changes in colonies allow identification.

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22
Q

Bacilli and vibrio bacteria are which shape?

A

Rods

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23
Q

Serological tests use which primary type of cell?

A

Antibodies

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24
Q

Describe the mechanism of the agglutination test.

A

Provides heavy cells which clump together if the particular pathogen is present - binds to antigen

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25
Q

Which type of test is ELIZA?

A

Serological

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26
Q

What is PCR?

A

Polymerase chain reaction - provides primers specific for the pathogen’s DNA to provide many copies

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27
Q

What is the difference between PCR and qPCR?

A

qPCR is viral - i.e. uses reverse transcriptase

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28
Q

Describe multi-locase sequence type.

A

Increases the resolution, and allows entire genome sequencing.

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29
Q

What does MALDI-TOF stand for?

A

Matrix assisted laser desorption/ionization - time of flight

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30
Q

Describe briefly the mechanism of MALDI-TOF.

A

Based on the m/q ratio. Splits into charged mass fragments which alters time of flight.

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31
Q

Which bacteria is MALDI-TOF NOT good for?

A

Staph and strep

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32
Q

Name the four main requested specific microbiology tests.

A

Blood culture, urine culture, faeces culture, swab of pus.

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33
Q

What is virulence?

A

Capacity to cause harm

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34
Q

What are commensal organisms?

A

‘Symbiotic’ endogenous organisms which live on the skin/body

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35
Q

What is an opportunistic pathogen?

A

A pathogen which takes advantage of a change of circumstance i.e HIV

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36
Q

Describe the structure of the gram positive cell wall.

A

Cell membrane with thick layers of peptidoglycan

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37
Q

Describe the structure of the gram negative cell wall.

A

Two cell membranes, separated by peptidoglycan. Lipopolysaccharide is present on outer membrane

38
Q

Which types of antibiotic target bacterial DNA?

A

Gyrases

39
Q

Which types of antibiotic target the cell wall?

A

Penicillins and glycopeptides

40
Q

Which types of antibiotic target the ribosome?

A

Protein synthesis inhibitors

41
Q

Which types of antibiotic target the cell membrane?

A

Sonication, ethanol

42
Q

What is beta-lactam?

A

A molecule which blocks the cross-links in the cell wall

43
Q

What is the difference between bacteriostatic and bacteriocidal?

A

Bacteriostatic inhibits growth, bacteriocidal kills bacteria

44
Q

What is meant by synergistic effects of antibiotics?

A

They multiply (i.e. 1 + 1 = 3)

45
Q

Why can broad spectrum antibiotics be bad in the elderly?

A

Increases risk of C. diff

46
Q

What are the three types of protozoa?

A

Amoeba, plasmodia, toxoplasmodia

47
Q

Which type (shape) of bacteria are coliforms?

A

Bacilli (rods)

48
Q

What gram stain is shown by coliforms?

A

Negative

49
Q

Describe when coliforms can be dangerous.

A

When they infect a sterile site.

50
Q

Coliforms contain two types of toxin. Describe them.

A

Endotoxins are parts of the cell wall that break off. Exotoxins are produced inside the cell and released.

51
Q

Endotoxins and exotoxins can be divided into two main types. What are these and what do they cause?

A

Prostaglandin E - fever. Cytokines - inflammation.

52
Q

Name two of the main beta-haemolytic streptococci.

A

Agalactase, pyogenes

53
Q

Name two of the main alpha-haemolytic streptococci.

A

Viridans, pneumoniae

54
Q

Name the main gamma-haemolytic streptococcus.

A

Enterococcus

55
Q

What is tropism?

A

The range of hosts a virus can infect

56
Q

How may a virus enter a cell?

A

Fusion of membranes, or endocytosis

57
Q

How are viral proteins assembled in a cell?

A

Own viral enzymes (protease), host ribosomes, reverse transcriptase

58
Q

How may viral fragments leave a cell?

A

Budding or lysis

59
Q

What is the name for the class of drugs which may affect viruses and bacteria?

A

Antimicrobials

60
Q

What is a convalescent viral infection?

A

One where there are no symptoms

61
Q

What is the main effect of continuous activation of the immune system by viruses? What’s dangerous about this?

A

Chronic inflammation - asymptomatic, infectious, and life threatening.

62
Q

Which newer tests may be used to detect viruses?

A

PCR, serology, mass spectroscopy

63
Q

B-lactam antibiotics include which four subtypes?

A

Penicillins, cephalosporins, carbapenems, monobactams

64
Q

Describe the mechanism of beta-lactam drugs.

A

A suicide substrate - resembles D-alanine D-alanine. Binds irreversibly and blocks cross links

65
Q

Which two types of antibiotic target the cell wall?

A

B-lactams and glycopeptides

66
Q

Which are the two main types of glycopeptides?

A

Vancomycin, teloplanin

67
Q

What are the major positives and negatives of the glycopeptides?

A

Treats MRSA, toxic buildup in kidney can cause failure, +ve only.

68
Q

Which are the good points about the penicillins?

A

Safe, effective, and flexible. Rapid excretion.

69
Q

Which are the bad points about the penicillins?

A

Resistance, hypersensitivity

70
Q

Which is the standard penicillin of choice for most general treatments?

A

Amoxicillin

71
Q

Which antibiotic is used in skin infections and why?

A

Flucloxacillin - targets +ve (narrow range), i.e. staph and strep

72
Q

What is co-amoxiclav?

A

Amoxicillin with clavulanic acid. A beta-lactam and beta-lactamase inhibitor.

73
Q

Which IV penicillin antibiotics are used in extreme infection? Why?

A

Temocillin - it is beta-lactamase and ESBL resistant. Piperacillin may also be used.

74
Q

Which long lasting penicillin is used intramuscularly?

A

Benzathine

75
Q

Name the 8 main penicillin types.

A

Amoxicillin, flucloxacillin, benzathine, piperacillin, temocillin, phenoxymethylpenicillin, co-amoxiclav, benzylpenicillin

76
Q

Give an account of the cephalosporins.

A

Broad spec and bacteriocidal, but encourage growth of c. diff. Rarely used in Tayside

77
Q

Which drugs are mainly bacteriostatic?

A

Tetracyclines, macrolides

78
Q

Name the macrolides.

A

Clarithromycin, azithromycin, erythromycin

79
Q

Name the two main bacteriocial antibiotics (excluding the B-lactams).

A

Aminoglycosides, gentamicin

80
Q

Why must blood levels of gentamicin regularly be monitored?

A

To avoid toxic buildup.

81
Q

Describe some methods of natural bacterial resistance.

A

Target isn’t present (i.e. no cell wall), not accessible, or different metabolism (anaerobic/aerobic)

82
Q

Which community of bacteria are particularly resistant to antibiotics? Which particular cell types?

A

Biofilms, persistor cells

83
Q

Which three main methods are encouraging antibiotic resistance?

A

Unneccessary doses, sub-optimal doses, selection pressure

84
Q

Bacteria can alter their permeability, to avoid antibiotics. Give the main methods of this.

A

Alters influx (reducing OmPF), alters efflux (pump i.e. tetracycline)

85
Q

Which enzymes form the B-lactamases?

A

Penicillinase, cephalosporinase

86
Q

Which enzymes form the ESBLs?

A

Carbapenamase, monobactamase, serine/metalloenzymes

87
Q

Which two enzymes are the main metalloenzymes?

A

New Delhi metallo-B lactamase 1, collastin

88
Q

How can bacteria transfer their genes?

A

Naturally, bacteriophage, sex pilli

89
Q

Which antibiotics affect folic acid synthesis?

A

Sulphonamides, trimethoprim

90
Q

Which antibiotics affect DNA gyrases?

A

Quinolones, fluroquinolones

91
Q

Which drug affects DNA replication in bacteria?

A

Metronidazole

PRINCIPLES (10 decks)

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