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Bacteriology > Antiobiotics I > Flashcards

Antiobiotics I Flashcards

1
Q

What is the minimum inhibitory concentration? How is it visualized in a test tube? How about an E-strip test, smarty pants?

A

The minimum concentration of drug needed to slow/stop bacterial production.

Visualized as the tube with lowest concentration of drug WITHOUT turbidity in it.

With an E-strip test, the MIC is seen as the concentration where the line of growth intersects the filter paper.

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2
Q

What is the minimum bactericidal concentration? How is it visualized in the lab.

A

The minimum concentration of drug needed in tissue to kill bacteria.

Tubes without turbidity from MIC test are taken and cultured on separate agar plates. The plate that demonstrates no growth represents the concentration necessary for MBC.

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3
Q

What are the five antibiotic mechanisms of action we learned in class?

A

1) Inhibition of cell wall synthesis
2) Inhibition of protein synthesis
3) Inhibition of nucleic acid synthesis
4) Disruption of cell membranes
5) Anti-Mycobacterium agents (not exactly a mechanism but whatever, it’s in top points)

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4
Q

What group of antibiotics function by inhibiting transpeptidation?

A

Beta-lactams

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5
Q

Peptidoglycan is composed of a backbone of _____ & _____, crosslinked by _____

A

Backbone = N-acetylmuramic acid (NAM) & N-acetylglucosamine (NAG)

Crosslinking is by peptide chains

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6
Q

How do beta-lactams work on Gram (-) and Gram (+) bacteria?

A

Gram (-): Bind to and block enzyme that carries our transpeptidation between D-Ala and H2N-DAP

Gram (+): Prevents rxn between pentaglycine bridge and D-Ala

D-Ala involved in both instances!

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7
Q

What determines the activity, spectrum, pharmacologic properties and resistance of beta-lactams?

A

R groups

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8
Q

_____ is a bacterial enzyme that opens the beta-lactam ring via a hydrolysis rxn.

A

Beta-lactamase

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9
Q

T/F Penicillins are bacteriostatic

A

FALSE

Penicillins are bactericidal

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10
Q

What are the bacterial mechanisms of resistance to penicillins?

A

1) Alter affinity of transpeptidases to penicillins
2) Beta-lactamase production
3) Efflux pumps
4) Impermeable membranes (poor penetration)

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11
Q

Penicillins are widely distributed in tissues and secretions except _____, _____, and _____

A

CNS, prostatic fluid, and eye

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12
Q

T/F Penicillins are ineffective against intracellular pathogens

A

TRUE

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13
Q

What species are susceptible to Bacitracin?

A

1) G+ cocci/bacilli
2) Neisseria
3) H. influenza
4) T. pallidum

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14
Q

D-cycloserine is used as a ______. What is the characteristic side effect of an exceeded oral dose?

A

2nd line TB drug

Common neuropsychiatric side effects with exceeded oral dose

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15
Q

What species are resistant to Bacitracin?

A

1) Enterobacteriaceae
2) Pseudomonas
3) Nocardia

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16
Q

What are the four non-beta-lactam inhibitors of cell wall synthesis?

A

1) D-Cycloserine
2) Bacitracin
3) Vancomycin
4) Fosfomycin

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17
Q

T/F Bacitracin is commonly administered orally.

A

FALSE

Bacitracin is nephrotoxic, and is therefore ONLY used topically. Typically in a “triple antiobiotic” ointment with neomycin and polymyxin

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18
Q

What organisms are covered by Fosfomycin? Which are resistant?

A

Covers G+ & G- organisms (broad spectrum)

Anaerobes are resistant

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19
Q

What kind of infection is Fosfomycin typically used for?

A

Uncomplicated UTIs

20
Q

What organisms does Vancomycin cover?

A

G+ ONLY (Narrow spectrum)

21
Q

For what kind of infections is Vancomycin used?

A

1) MRSA/MRSE
2) C. diff
3) Enterococcus
4) G+ infections in pts. with penicillin allergy

22
Q

T/F Organisms using D-Ala-D-Lac in their cell walls are good targets for Vancomycin

A

FALSE

Organisms using D-Ala-D-Lac in the cell walls are RESISTANT to Vancomycin (can’t bind D-Ala-D-Lac)

Vancomycin binds D-Ala-D-Ala

23
Q

Penicillin is used for infections by _____ aerobes except for _____.

A

G+ aerobes EXCEPT Staph. (S. pneumo, S pyogenes, S. viridans endocarditis

24
Q

Penicillin V covers G+ aerobes (except staph). What does penicillin G cover?

A

1) Anaerobes
- EXCEPT B. faecalis

2) Meningococcus
- NOT gonogoccus

3) Spirochete diseases

25
Q

Oxacillin, cloxacillin, dicloxacillin and nafcillin are all examples of _____ penicllins

A

Isoxazolyl penicillins

26
Q

T/F Isoxazolyl penicillins cover MRSA

A

FALSE

MRSA is resistant to Isoxazolyl penicillins

27
Q

Ampicillin and amoxicillin are examples of _____ penicillins

A

Aminopenicillins

28
Q

Aminopenicillins, broad spectrum abx, are typically ineffective against beta-lactamase positive organisms. What is administered to patients to allow aminopenicillins to work against these organisms?

A

Beta-lactamase inhibitors.

These effectively increase the spectrum of aminopenicillins.

29
Q

What kinds of infections are aminopenicillins used for (5)?

A

1) URI
2) Otitis media (H. influenza)
3) Uncomplicated UTI (E. Coli)
4) Acute meningitis (kids)
5) Typhoid fever (salmonella)

30
Q

What type of penicillin is used as an anti-pseudomonas drug?

A

Carboxypenicillin/Ureidopenicillin

Ticarcillin is the specific drug. Above is the lass.

31
Q

When combined, what anti-pseudomoal penicillins have the broadest spectrum? What is the trade name of this combination?

A

Piperacillin (ureidopen.) + Tazobactam

Trade name = zosyn

32
Q

T/F The action/resistace of cephalosporins are essentially the same as penicillins

A

TRUE

33
Q

Cefazolin, cefuroime and cephadroxil are all _____ cephalosporins

A

First generation

34
Q

First generation cephalosporins work excellently against susceptible _____ & _____. They are used for _____/_____ infections.

A

First generation cephalosporins work excellently against susceptible STAPH & STREP. They are used for SKIN/SOFT TISSUE infections.

35
Q

Cefaclor, cefuroxime, and cefprozil are all _____ cephalosporins

A

Second generation

36
Q

Second generation cephalosporins have _____ activity against G+ organisms, and _____ on G- organisms and anaerobes

A

Modest activity against G+

Increased activity against G- and anaerobes

37
Q

What are second generation cephalosporins used to treat?

A

POLYMICROBIAL INFECTIONS!

1) Diabetic foot ulcers
2) PID
3) Respiratory tract infections (upper and lower)
4) Intraabdominal infections

38
Q

Ceftriaxone, cefotaxime, cefoperazone, and cefpodoxime are the _____ cephalosporins

A

Third generation cephalosporins

39
Q

_____ cephalosporins are the drug of choice for severe infections

A

Third generation cephalosporins

40
Q

What organisms are resistant to third generation cephalosporins?

A

1) Listeria

2) B-lactamase positive Pneumococci

41
Q

Third generation cephalosporins are broad spectrum abx that are the drug of choice or serious infections. Which infections are specifically included in their coverage?

A

1) G- sepsis
2) Lyme disease
3) Bacterial meningitis (Ceftriaxone)
- EXCEPT Listeria and Pneumococci w/beta-lactamase

42
Q

The only fourth generation cephalosporin is _____

A

Cefepime

43
Q

Cefepime (a fourth generation cephalosporin) has the same antimicrobial spectrum as third generation cephalosporins, but resists more _____. It is good for _____ infections.

A

Resists more beta-lactamases

Good for nosocomial infections

44
Q

The only fifth generation cephalosporin is _____

A

Ceftaroline

45
Q

T/F Ceftaroline (5th gen) has the same spectrum as Cefepime (4th gen.), but works better against P. aerguinosa.

A

FALSE

Ceftaroline does NOT cover Pseudomonas

46
Q

Imipinem is a carbapenem that is _____ spectrum. It covers _____ and _____

A

Broad spectrum

Covers anaerobes and Pseudomonas

47
Q

Aztreonam is a monobactam that is _____ spectrum. It covers ONLY _____ including _____

A

Narrow spectrum

Covers only G- AEROBES including Pseudomonas

Bacteriology (19 decks)

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