Microbiology Flashcards

1
Q

Gram+ organisms stain…

A

Purple

Stain well due to thick peptidoglycan layer

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2
Q

Gram- organisms stain…

A

Pink

Thinner peptidoglycan layer doesn’t retain stain well

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3
Q

Endotoxin is produced by…

A

Gram- organisms

Part of the cell wall

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4
Q

Exotoxin is produced by…

A

Gram+ organisms

Exported from the cell

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5
Q

Gram+ cocci in chains are?

A

Streptococci

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6
Q

Gram+ cocci in clusters are?

A

Staphylococci

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7
Q

The test to classify different Streptococci spp.?

A

Haemolysis
Alpha (partial) - Strep. pneumoniae + viridans
Beta (complete) - Group A (pyogenes) and B Strep.
Gamma (none) - Enterococcus sp.

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8
Q

Examples of: Alpha-haemolytic Streptococci?

A

Strep. pneumoniae + “viridans” group

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9
Q

Examples of: Beta-haemolytic Streptococci?

A

Group A Strep. (Strep. pyogenes), Group B Strep.

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10
Q

Examples of: Non-haemolytic Streptococci?

A

Enterococcus sp.

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11
Q

The test to distinguish Staphylococcus aureus from other Staph. spp.?

A

Coagulase test
+ve = Staph. aureus
-ve = other Staph. spp. (common skin commensals)

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12
Q

Treatment of choice for Staph. aureus infection?

A

Flucloxacillin

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13
Q

Examples of gram- cocci in pairs (diplococci)

A

Neisseria meningitidis and Neisseria gonorrhoeae

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14
Q

Some examples of Gram- bacilli

A
Bordetella
H. influenzae
Coliforms
Pseudomonas
Campylobacter
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15
Q

Examples of coliforms that are gut commensals

A

E. coli
Klebsiella sp.
Proteus sp.

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16
Q

Examples of coliforms that are gut pathogens

A

Salmonella sp.
Shigella sp.
E. coli 0157

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17
Q

The name of the toxin produced by E. coli 0157 is…

A

Verotoxin (VTEC)

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18
Q

Treatment of choice for coliform infections?

A

Gentamicin

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19
Q

Examples of strict aerobes (2)

A

Pseudomonas sp. (Gram- bacilli)

Legionella sp. (Gram- bacilli)

20
Q

Examples of strict anaerobes (2)

A

Clostridium spp. (Gram+ bacilli)

Bacteroides spp. (Gram- bacilli)

21
Q

Treatment of choice for anaerobic infections?

A

Metronidazole

22
Q

Genetic variation in bacteria is dangerous because…

A

Resistance to antibiotics may develop.

23
Q

Gene transfer: Transformation

A

DNA from dead bacteria is taken up by living bacteria and incorporated into plasmids/bacterial chromosome.

24
Q

Gene transfer: Conjugation

A

Sex pilus forms between bacteria to allow transfer of plasmid DNA.

25
Q

Gene transfer: Transduction

A

Viruses can transfer bacterial DNA between cells they infect.

26
Q

The 5 methods of spread of infection are…

A

Inhalation, Ingestion, Inoculation, mother to Infant, Intercourse

27
Q

Viruses contain RNA or DNA, never both. True/False?

A

True

Size of their capsid (protein coat) limits space

28
Q

Bactericidal antibiotics inhibit cell growth. True/False?

A

False

Kill bacteria directly - bacteriostatic inhibits cell growth

29
Q

Vancomycin is part of which family of antibiotics?

A

Glycopeptides

30
Q

Penicillins, cephalosporins and glycopeptides act on the bacterial ___ ___

A

Cell wall

31
Q

Penicillins are bactericidal/bacteriostatic, safe/not safe in pregnancy, excreted via kidneys/urine/liver

A

Bactericidal, safe in pregnancy, kidneys

32
Q

Benzylpenicillin is given IV and is AKA penicillin V. True/False?

A

False

Penicillin G; phenoxymethyl-penicillin is AKA penicillin V

33
Q

Flucloxacillin is a ___ spectrum antibiotic. Which organisms is it effective against?

A

Narrow

Staph and Strep only (1st line for Staph aureus)

34
Q

Beta lactamase destroys which antibiotic?

A

Amoxicillin

35
Q

Co-amoxiclav is probs the best antibiotic to have on a desert island - why?

A

Treats everything apart from Pseudomonas and MRSA

Can be taken orally or IV

36
Q

Cephalosporins are bactericidal/bacteriostatic, safe/not safe in pregnancy, excreted via kidneys/urine/liver

A

Bactericidal, safe in pregnancy, kidneys + urine

37
Q

Glycopeptides are only active against Gram _ cell walls

A

+ve

38
Q

Can you name the 3 macrolides?

A

Erythromycin, clarythromycin, azythromycin

39
Q

Gentamicin belongs to which class of antibiotics?

A

Aminoglycosides

40
Q

Macrolides are bactericidal/bacteriostatic, safe/not safe in pregnancy, excreted via kidneys/urine/liver

A

Bacteriostatic, erythromycin safe in pregnancy, liver

41
Q

Gentamicin [aminoglycoside] is bactericidal/bacteriostatic, safe/not safe in pregnancy, excreted via kidneys/urine/liver

A

Both bacteriostatic + bactericidal, not safe in pregnancy, urine

42
Q

Name the antibiotics that act on bacterial DNA

A

Metronidazole, trimethoprim +/- sulphanimide, fluoroquinolones

43
Q

Metronidazole is bactericidal/bacteriostatic, safe/not safe in pregnancy, treats aerobes/anaerobes

A

Bactericidal, safe in pregnancy, anaerobes (Clostridium and Bacteroides)

44
Q

Trimethoprim +/- sulphonamide is bactericidal/bacteriostatic, can be combined with sulphonamide to form _____

A

Bacteriostatic, co-trimoxazole

45
Q

The 4 antibiotics that most commonly cause C diff infection are…

A

Ciprofloxacin
Co-amoxiclav
Clindamycin
Cephalosporins (ceftriaxone)