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Flashcards in Antibiotics 2 Deck (105):
1

What 2 classes of Abs are cell wall inhibitors?

penicillins and cephalosporins

2

What are the 2 classes of protein synthesis inhibitors?

tetracyclines and macrolides

3

What is the 1 class of DNA synthesis inhibitors?

fluoroquinolones

4

Targeting the synthesis of _____ is one of the most widely effective and least toxic antibiotic strategies

bacterial cell walls

5

What are cell wall inhibitors only effective against?

actively growing bacteria

6

How does penicillin inhibit cell wall synthesis?

it inhibits transpeptidase that forms cross links between peptidoglycan chains that are essential for cell wall integrity
- causes osmotic pressure on the cells resulting in cell lysis

7

What enzyme does gram positive bacteria product to break down the cell wall?

- produces autolysins

8

Without active cell wall synthesis ____ can damage the cell

autolysins

9

What are the 2 examples of penicillinase resistant penicillins

- methicillin and cloxacillin

10

What are the 2 examples of extended spectrum penicillins

- ampicillin and amoxicillin

11

Are penicillins bactericidal or bacteriostatic?

Bacteriocidal

12

Penicillin V and Amoxicillin are only available as ______

oral preparations

13

Pipercillin must be through the _____ route

IV/IM

14

Why do penicillins affect the composition of the intestinal flora?

- because they are incompletely absorbed

15

Absorption of penicillinase resistant antibiotics are ___ by food in the stomach and must be administered ______

reduced
- before a meal or 2-3 hours after

16

Does penicillin cross the placenta? What abut the bone or CNS?

- does cross the placenta
- does not penetrate the bone or CNS

17

Where is penicillin excreted?

- in the urine and breast milk

18

What are the most common adverse effects of penicillins?

- GI effects relatively common but are seldom severe due to the disruption of normal intestinal microflora
- allergy to its metabolite penicilloic acid relatively common (rash, swelling, anaphylaxis)
- cross allergy within the penicillin class
- no negative birth effects

19

_____ is a concern in patients receiving anticoagulants also also on penicillin

Reduced coagulation

20

What are the 4 antibiotics that fall under the class of cephalosporins?

cephalxin, cephalothin, cepazolin, cefepime

21

Which cephalosporins are the only 2 Abs administered orally?

- cephalexin and cefixime

22

____ penetrates the bone

cefazolin

23

____ crosses the BBB

cefuroxime

24

____ and _____ penetrate the cerebrospinal fluid

cefotaxime and ceftriaxone

25

Where are most cephalosporins excreted?

- most are eliminated in the urine
(cefriaxone is excreted in the bile- longest t1/2 of all cephalosporins)

26

How do protein synthesis inhibitors work?

Bind to 70S ribosomes (in bacterial cells) opposed to the 80S ribosomes that are in mammalian cells
- effective against gram positive and gram negative bacteria as well as other micro organisms

27

What are the 5 classes of antibiotics that fall under the protein synthesis inhibitors class?

- tetracyclines
- amino-glycosides
- macrolides
- chloramphenicol
- clindamycin

28

How do tetracyclines act as a protein synthesis inhibitor?

- binds irreversible to the 30S ribosome
- blocks acyl-tRNA access to the ribosome

29

Tetracyclines are considered ____ spectrum and are bacterio____

broad
bacteriostatic

30

What is the naturally occurring tetracycline?

tetracycline

31

What is the semi-synthetic tetracyclines?

- doxycycline
-methacycline
- minocycline

32

Absorption PO of tetracycline is reduced by the consumption of ____ and ____

dairy foods and antacids

33

Describe the distribution of tetracyclines. Where do they concentrate? What do they cross?

- distribution is throughout the body and body fluids
- concentrates in the liver, kidney, and spleen
- crosses the placenta and penetrates the bone and teeth

34

Where are tetracyclines excreted?

- metabolized and conjugated to form glucuronides by the liver and secreted in the bile and enters the urine via glomerular filtration
- excreted as well in the breast milk

35

What are the adverse effects of tetracyclines?

- GI discomfort- overcome by consuming food with the pills
- deposition in bones and teeth of growing children
- hepatotoxicity
- sunburn (increased sensitivity to UV rays)
- dizziness, nausea and vomiting
(minocycline and doxycycline concentrate in the inner ear)
- headache/blurred vision
- superinfection: resistance is common
- not recommended or patients with kidney/liver disease or pregnant/lactating women

36

How do aminoglycosides act as a protein synthesis inhibitor?

- binds irreversibly to the 30S ribosome
- blocks functional assembly of the ribosome

37

Amino glycosides are effective against _______

aerobic gram negative bacteria

38

Is aminoglycosides bacteriocidal or bacteriostatic

bacteriocidal

39

What Abs are derived from streptomyces?

streptomycin
kanamycin

40

What Abs are derived from micromonospora?

gentamicin
amikacin

41

Molecular properties of aminoglycosides prevent ____ absorption

oral

42

Describe the distribution of aminoglycosides in the body?

- levels achieved in most tissues are low
- concentrates in the renal cortex and the inner ear
- low penetration into the cerebrospinal fluid
- crosses the placenta and enters the fetal circulation

43

Where are aminoglycosides excreted?

the urine

44

What are the adverse effects associated with aminoglycosides?

- nephrotoxicity - retention of aminoglycosides by proximal tubular cells disrupts calcium mediated transport
- ototoxicity - deafness caused by the destruction of hair cells within the inner ear (fetuses and elderly are the most susceptible)
- neuromuscular paralysis- high dose toxicity from injections
- allergic reactions

45

How do macrolides act as protein synthesis inhibitors?

- bind irreversibly to the 50S ribosome
- blocks peptidyl transfer

46

Macrolides are ____ spectrum and effective against gram ___ bacteria

broad
positive

47

What macrolide Abs are derived from streptomyces

-erythromycin
- clarithromycin
- azithromycin

48

What macrolides are derived from the synthetic ketolides?

telithromycin

49

Macrolides are ____ administered

orally

50

___ interferes with the absorption of macrolides.

food

51

What is one method of ensuring that erythromycin does not get destroyed in the gastric acid of the stomach?

can enteric coat the tablets

52

Describe the distribution of macrolide Abs?

- distributes throughout the body
- does not penetrate the cerebrospinal fluid
- concentrates in the liver

53

Where are macrolide Abs excreted? What about their inactive metabolites?

- excreted in the bile
- inactive metabolites are secreted in the urine

54

What are the adverse effects associated with using macrolides?

- GI problems
- jaundice
- ototoxicity (associated with high doses of erythromycin)
- prolonged QT c interval- patients with existing arrhythmia (erythromycin, clarithromycin)
- myopathy - interactions with statins due to the inhibition of CYP 3A4

55

In what case would we use Quinupristin/Dalfopristin (synercid)?

- reserved for the treatment of vancomycin resistant enterococcus
- mixture of 2 drugs in a ratio of 70:30
- binds to separate sites on the ribosome (Quinupristin binds to the 50S subunit preventing peptide elongation while dalfopristin binds to the 23S subunit preventing peptide transfer
- tx of gram + cocci
- bactericidal with a long post Ab effect

56

What is the administration route of synercid

IV/IM

57

What is the distribution of synercid?

- penetrates macrophages and polymorphonucleosites- VREs grow intracellularly
- low levels in the cerebrospinal fluid

58

Where is synercid excreted?

in the bile
- secondarily excreted in the urine

59

What are the adverse effects of synercid?

- venous irritation when given IV
- joint/muscle ache in patients given high doses
- hyperbilirubinemia (bilirubin is elevated in about 25% of patients)
- causes inhibition of P450

60

What are the two enzymes that are inhibited by DNA synthesis inhibitors?

- bacterial topoisomerase
- DNA gyrase

61

What are two examples of DNA synthesis inhibitors?

- fluorowuinolones
- rifamycin

62

What enzyme does fluoroquinolones inhibit?

- DNA gyrase

63

What route of administration are fluoroquinolones given?

- via the oral/IV route

64

What mineral interferes with oral absorption of fluoroquinolones?

- dietary calcium

65

What is the distribution of the fluoroquinolones?

- distributes well throughout the tissues
- levels are high in the bones, kidney and prostate
- low penetration into the cerebral spinal fluid
- crosses the placenta and enters fetal circulation

66

Where are fluoroquinolones excreted?

the urine

67

List the adverse effects of fluoroquinolones?

- GI disturbances
- CNS - light headed, dizziness
- phototoxicity
- cartilage erosion (should not be administered to pregnant or nursing women)

68

What is the most commonly prescribed fluoroquinolone?

- ciprofloxacin

69

What infections is ciproflxacin generally used to treat?

- infections of the bones/joints
- infections of the respiratory tract
- infections of the urinary tract

70

Administration of fluoroquinolones at the same time as ____substantially reduces absorption

calcium, antacids, zinc, magnesium

71

What are the drug interactions that ciproflaxacin has?

- alters level of drugs metabolized by the cytochrome P450 enzyme
- warfarin levels can be dangerously increased
- increased seizure risk when combines with NSAIDS
- affects the renal clearance of other drugs such as methotrexate

72

What infections is moxiflaxacin used to treat?

- respiratory tract infections
- endocarditis
- meningitis
- conjunctivitis

73

Concurrent administration of moxifloxacin along with ____ significantly reduced absorption

- aluminum or mangesium

74

What is moxifloxacin's adverse drug reactions?

- may prolong the QTc interval - should not be used in patients with cardiac arrhythmias
-

75

What drug interactions are associated with moxifloxacin?

- does not inhibit the cut p450 enzyme
- may interact with warfarin

76

What antibacterials ball under the category of metabolite synthesis inhibitors?

- sulfonamides
- trimethoprim

77

Sulfonamides inhibit the synthesis of bacterial _____ acid

dihydrofolic acid

78

What bacteria are sulfonamides active against?

- most gram positive and many gram negative bacteria - broad spectrum

79

Bacteria that _________ are inherently resistant for sulfonamides

obtain folate from the environment

80

What is considered a short acting sulphonamide?

- sulfamethazole
- sulfadiazine

81

What is considered an intermediate acting sulfonamide?

- sulfacetamide
- sulfadoxine

82

What is considered to be a long acting sulfonamide?

sulfadimethoxine

83

Where are sulfonamides absorbed?

- in the small intestine

84

Describe sulfonamide distribution

- crosses the BBB and penetrates the CSF
- crosses the placenta and gets into fetal circulation

85

Where are sulfonamides excreted?

- active and inactive metabolites secreted in the urine
- secreted into the breast milk

86

What are the adverse effects of sulfonamides?

- allergies common
- kernicterus- sulfonamide displaces bilirubin from binding albumin causing free bilirubin to cross the undeveloped BBB and pass into the CNS
- nephrotoxicity (solubility of sulfonamides is low)
- hemolytic anemia

87

What are the drug interactions associated with sulfonamides?

- potentiate the hypoglycaemia effect of tolbutamide
- potentiate the anticoagulant effect of warfarin

88

Trimethoprim inhibits the synthesis of bacterial ______

tetrahydrofolic acid

89

What is trimethoprim active against?

- against most gram positive and many gram negative bacteria
- broad spectrum

90

Trimethoprim is used in the treatment of what?

- urinary tract infections
- vaginal infections
- bacterial prostatitis
- prophylaxis

91

Absorption of trimethoprim is where?

in the small intestine

92

Where is trimethoprim distributed?

- penetrates CSF
- crosses the placenta and affects fetal folate metabolism
- distributed widely throughout the body

93

Where is trimethoprim excreted?

- in the urine

94

What are the adverse effects of trimethoprim?

- contraindicated in pregnancy (doubling of miscarriage rates)
- thrombocytopenia (low levels of platelets, pregnant women and those with poor diets are at a higher risk

95

What does trimethoprim interact with?

- potentiates the anticoagulant effects of warfarin

96

What 2 medications make up cotrimoxazole?

- composed of both trimethoprim (more lipid soluble) and sulfonamethazole in a 1:5 ratio

97

There is _____ activity in cotrimoxazole from the sequential inhibition of ______

synergistic
folate synthesis

98

What is the advantage of using cotrimoxazole over other sulfonamides?

- broader spectrum

99

Cotrimoxazole is used generally in the treatment of what infections?

- urinary tract infections
-respiratory tract infections
- kidney infections
- GI tract infections
- septicemia
- prophylaxis in HIV patients

100

Where is cotrimoxazole absorbed?

in the small intestine

101

Cotrimoxazole is distributed where in the body?

- throughout the body
- crosses the BBB very slowly
- crosses the placenta and affects fetal folate metabolism

102

Where is cotrimoxazole excreted?

in the urine

103

What are the adverse effects associated with cotrimoxazole use?

- contraindicated for pregnant women
- hematologic (thrombocytopenia, anemia, leukopenia)
- skin rashes are common and can be severe in the elderly
- nausea/vomiting
- jaundice, renal damage/ failure
- rashes/diarrhea (common along immunocompromised patients)

104

What are the drug interactions that are associated with cotrimoxazole?

- potentiate the anti-coagulant effect of warfarin
- methotrexate is displaced for albumin binding sites

105

Normal GI and vaginal flora are disrupted with antibiotic use, contributing to 4 major side effects

nausea, vomiting, diarrhea and yeast infections