1 - TOPICAL ANTIBACTERIAL AGENTS Flashcards Preview

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Flashcards in 1 - TOPICAL ANTIBACTERIAL AGENTS Deck (150):
1

Bacitracin is a topical antibacterial agent used for wound care and minor bacterial infections

True (can be combined with Polymyxin B and possibly also Neomycin to provide a wider spectrum of bacterial coverage)

2

Polymixin B is a topical antibacterial agent used for wound care and minor bacterial infections

True (not available as an individual product, usually in combination with Bacitracin as a 'double antibiotic'/Bacitracin and Neomycin as a 'triple antibiotic' to broaden coverage against gram -Ve bacteria especially pseudomonas)

3

Mupirocin (Bactroban) is a topical antibacterial agent used for wound care and minor bacterial infections

True

4

Neomycin is a topical antibacterial agent used for wound care and minor bacterial infections

True (not available as an individual product, usually in combination with Bacitracin and Polymixin B as a 'triple antibiotic')

5

Retapamulin is a topical antibacterial agent used for wound care and minor bacterial infections

True

6

Gentamicin is a topical antibacterial agent used for wound care and minor bacterial infections

True

7

Silver sulfadiazine and iodoquinol are topical antibacterial agents used for wound care and minor bacterial infections

True

8

Iodoquinol is a topical antibacterial agent used for wound care and minor bacterial infections

True

9

Bacitracin is minimally effective for eliminating nasal carriage of S. Aureus

True (Mupirocin is superior)

10

A double-blind study comparing bacitracin with white petrolatum found no statistical difference in the postoperative infection rate in dermatologic surgery patients

True (90% of the wound infections in the petrolatum group were due to MSSA whereas the patients treated with bacitracin grew Ciprofloxacin-sensitive gram -Ve bacteria; given the higher cost of treating gram -Ve infections, the 0.9% risk of contact dermatitis and higher cost of bacitracin, It is less expensive to treat clean dermatologic surgical wounds with white petrolatum)

11

There is no systemic absorption of topical bacitracin

True

12

Common adverse effects with topical bacitracin include localised itching and burning

True

13

Bacitracin is a frequent allergen in patients with chronic stasis dermatitis or keratoconjunctivitis

True (barrier disruption in patients with stasis dermatitis and chronic leg ulcers may allow the development of contact dermatitis resulting in positive patch test results, thus long-term use on non-intact skin encountered in stasis ulcers or chronic inflammatory dermatoses may lead to an increased risk of contact allergy)

14

There have been a significant number of reported cases of anaphylactic shock due to topical bacitracin

True (most cases involved patients who had used bacitracin on non-intact skin such as ulcers)

15

Bacitracin often co-reacts (not a true cross-reaction as both are chemically unrelated) with Neomycin such that patch testing to both may uncover a Neomycin allergy which is the most common cause of postoperative allergic contact dermatitis

True (the co-reaction is believed to be due to coincidental sensitisation as Bacitracin is chemically unrelated to Neomycin but both antibacterial agents are commonly found in combination) - though Neomycin cross-reacts with other aminoglycosides such as streptomycin, kanamycin, gentamicin, tobramycin

16

Contact allergy to Polymyxin B in the absence of concomitant positive reactions to Neomycin and Bacitracin is very rare

True (usually combined with other antibacterial agents to broaden coverage against gram -Ve bacteria including pseudomonas)

17

Polymyxin B is not a significant allergen in postoperative wounds in dermatologic surgery patients

True

18

There is little systemic absorption and few systemic reactions even when Polymyxin B is applied to open wounds because Polymyxin B binds avidly to cell membranes

True

19

Because bacterial resistance to Neomycin has been reported in both gram +Ve and gram -Ve bacteria, Neomycin is virtually always used in combination with other topical antibacterial agents (Bacitracin and Polymyxin B to produce the 'triple antibiotic')

True

20

Bacitracin is typically added for its gram +Ve coverage

True (Polymyxin B is typically added to provide coverage for pseudomonas)

21

Polymyxin B is typically added to provide coverage for pseudomonas

True (whereas Bacitracin is typically added for its gram +Ve coverage)

22

Systemic toxicity to Neomycin (an aminoglycoside) includes ototoxicity and nephrotoxicity, although systemic absorption and toxicity do not occur when the antibacterial agent is used topically on minor skin lesions

True (Neomycin-related deafness has been reported but usually involving a Neomycin solution to irrigate a large wound, and rarely from ear drops containing Neomycin where this should not be used in patients with tympanic membrane perforation)

23

Bacitracin is bactericidal against gram +Ve and Neisseria species by interfering with bacterial cell wall synthesis

True (inhibition of phospholipid receptors involved in peptidoglycan synthesis)

24

Polymyxin B is bactericidal against gram -Ve bacteria and pseudomonas by increasing the permeability of bacterial cell membrane

True (occurs by interacting with phospholipid components of the cell membrane)

25

Neomycin (an aminoglycoside) is bactericidal against gram +Ve and gram -Ve bacteria by inhibiting protein synthesis, and is typically used for its gram +Ve coverage

True (occurs by binding to 30s subunit of ribosomal RNA)

26

Mupirocin (Bactroban) is bactericidal against MRSA and strep pyogenes by inhibiting bacterial RNA and protein synthesis

True (occurs by reversibly bonding to bacterial isoleucyl-tRNA synthetase) - Mupirocin is not active against anaerobic bacteria

27

Bacitracin is derived from Bacillus subtilis

True

28

Polymyxin B is derived from Bacillus polymyxa

True

29

Neomycin is derived from Streptomyces fradiae

True

30

Mupirocin is derived from P. fluorescens

True

31

Retapamulin is a semi-synthetic derivative of Clitopilus scyphoides

True

32

Gentamicin is derived from Micromonospora Purpurea

True

33

Silver sulfadiazine is synthesised from a reaction of silver nitrate and sodium sulfadiazine

True

34

Iodoquinol is a synthetic halogenated derivative of quinolone

True

35

Systemic absorption of Mupirocin is minimal and cutaneous metabolism is <3%, leaving most of the drug on the skin for antibacterial activity

True

36

95% of Mupirocin is protein bound, therefore it may be less effective on weeping wounds (drainage of serum/protein and clearance of the drug)

True

37

Mupirocin is used to treat skin infections frequently initiated by staph and strep, including impetigo, folliculitis, impetiginised eczema, burns, lacerations and leg ulcers

True

38

Mupirocin ointment is equivalent to PO erythromycin for the treatment of impetigo and is approved as a monotherapy

True (the higher cost of Mupirocin is offset by the increased incidence of adverse effects and lost production due to erythromycin)

39

Intranasal Mupirocin is effective for the elimination of staph, even MRSA from chronic carriers and most recent studies advocate BD application for 5 days, and prolonged suppression of nasal staph carriage is achieved by weekly dosing or monthly courses

True

40

Intranasal Mupirocin in combination with Chlorhexidine soap reduced nosocomial staph aureus surgical site infections in nasal carriers, whereas Intranasal Mupirocin alone is ineffective for this purpose

True

41

Among nasal MRSA carriers undergoing Mohs surgery, no postoperative MRSA infections occurred in patients who used Intranasal Mupirocin and PO Bactrim for 5-7 days

True

42

Most reactions associated with Mupirocin are localised pain, burning and itching which is attributed to the polyethylene glycol in the vehicle base because the incidence is no greater than with the vehicle alone

True (the nasal formulation is in WSP base and does not contain polyethylene glycol and so it is less irritating on mucosal surfaces)

43

Mupirocin does not cross-react with other topical antibacterials due to its unique structure

True

44

True allergic contact sensitivity to Mupirocin is extremely rare; and unlike Bacitracin and Neomycin, Mupirocin is an uncommon cause of postoperative allergic contact dermatitis following dermatologic surgery

True (Mupirocin is an uncommon sensitiser)

45

Retapamulin is bacteriostatic against strep pyogenes, Mupirocin-resistant staph aureus, MRSA and anaerobes by inhibiting bacterial protein synthesis

True (occurs by binding to protein L3 on the 50s ribosomal subunit)

46

Retapamulin has no clinically relevant cross-resistance with other antibacterials due to its unique structure

True

47

Retapamulin is FDA-approved for the treatment of primary impetigo due to methicillin susceptible staph aureus or strep pyogenes in adults and children 9 months of age and older

True (recommended BD for 5 days for the treatment of impetigo)

48

The most frequent adverse effects of Retapamulin are localised pruritus, paraesthesia, irritation or pain at the application site

True

49

Retapamulin may cause an allergic contact dermatitis with positive patch testing

True

50

Gentamicin is bactericidal against gram +Ve (excluding strep) and notably gram -Ve organisms including pseudomonas, by inhibiting bacterial protein synthesis

True (occurs by irreversibly binding to 30s ribosomal subunits)

51

Gentamicin is an uncommon sensitiser although rarely allergic contact dermatitis is found in patients with Rosacea thought to be secondary to prior antibiotic treatment of ocular disease

True

52

Neonatal patients who used gentamicin ointment for ocular infection prophylaxis developed periocular ulcerative dermatitis

True

53

Silver sulfadiazine is bactericidal against gram +Ve (including MRSA) and gram -Ve organisms (especially pseudomonas in burn wounds) by inhibiting bacterial replication

True

54

Silver sulfadiazine has a low toxicity profile although caution should be exercised with application to large burn sites and with prolonged use in bullous disorders as renal insufficiency has been reported with significant absorption

True

55

Silver sulfadiazine may cross-react with patients who have a sulfonamide allergy

True (due to the shared sulfa moiety)

56

Silver sulfadiazine may cause haemolytic anaemia in patients with G6PD deficiency due to the cross-reaction with sulfonamide

True

57

Iodoquinol is active against gram +Ve (including MRSA) and gram -Ve organisms (including pseudomonas) as well as being a broad spectrum agent against dermatophytes and may be useful in the treatment of fungal infections complicated by secondary bacterial involvement

True

58

Benzoyl peroxide is used as a topical antibacterial agent for acne and rosacea

True

59

Clindamycin is used as a topical antibacterial agent for acne and rosacea

True

60

Erythromycin is used as a topical antibacterial agent for acne and rosacea

True

61

Metronidazole is used as a topical antibacterial agent for acne and rosacea

True

62

Azelaic acid is used as a topical antibacterial agent for acne and rosacea

True

63

Dapsone is used as a topical antibacterial agent for acne and rosacea

True

64

Sodium sulfacetamide is used as a topical antibacterial agent for acne and rosacea

True

65

Benzoyl peroxide is a broad spectrum bactericidal topical antibacterial agent (including P. acnes) derived from organic peroxide

True

66

Clindamycin (semi-synthetic derivative of lincomycin derived from Streptomyces species) is a broad spectrum topical antibacterial agent with good gram +Ve and anaerobic cover which inhibits bacterial protein synthesis and may produce bactericidal or bacteriostatic effects

True

67

Erythromycin is a macrolide antibacterial agent isolated from Streptomyces erythraeus and is bactericidal against most gram +Ve bacteria and P. acnes by inhibiting bacterial protein synthesis by reversibly binding to the 50s subunit of the bacterial ribosome

True

68

Metronidazole is a synthetic nitroimidazole antibacterial agent with aerobic and anaerobic coverage which causes bacterial DNA disruption and inhibition of nuclei acid synthesis

True

69

Azelaic acid is a naturally occurring dicarboxylic acid with broad bacteriostatic and bactericidal activity including against P. acnes by inhibiting bacterial protein synthesis

True

70

Dapsone is a synthetic sulfone with bacteriostatic activity against Mycobacterium species via inhibition of dihydropteroate synthetase enzyme in the folate pathway

True

71

Sodium sulfacetamide is a synthetic molecule derived from aniline with antibacterial and anti-inflammatory properties commonly incorporated with sulphur (non-specific antifungal and antibacterial) which inhibits dihydropteroate synthetase enzyme of the folate pathway

True

72

Topical benzoyl peroxide is indicated for the treatment of mild-to-moderate acne vulgaris

True

73

Benzoyl peroxide reduces inflammation in acne lesions

True

74

Benzoyl peroxide has keratolytic and comedolytic properties

True (although antibacterial effects is >> keratolytic effects for acne)

75

The stability of benzoyl peroxide depends on the vehicle and it is least stable in propylene glycol

True

76

5% of topically applied benzoyl peroxide is absorbed through the skin and completely metabolised to benzoic acid in the skin then rapidly cleared by the kidneys without causing any systemic toxicity

True

77

Benzoyl peroxide, dapsone and sodium sulfacetamide are classified as pregnancy category C

True (Clindamycin, erythromycin, metronidazole and azelaic acid are classified as pregnancy category B instead)

78

Clindamycin, erythromycin, metronidazole and azelaic acid are classified as pregnancy category B

True (Benzoyl peroxide, dapsone and sodium sulfacetamide are classified as pregnancy category C)

79

Benzoyl peroxide has not been associated with induction of bacterial resistance and is therefore a useful adjunct to control antibiotic resistance by effectively reducing strains of P. acnes resistant to erythromycin, tetracyclines, and Clindamycin

True

80

Benzoyl peroxide is as effective as erythromycin or Clindamycin for inflammatory acne lesions

True

81

Benzoyl peroxide is more effective than erythromycin or Clindamycin for non-inflammatory acne lesions

True

82

Benzoyl peroxide is comparable to Tretinoin (retinoid) in treating non-inflammatory acne lesions but superior in treating inflammatory acne lesions

True

83

Benzoyl peroxide is comparable to Adapalene (retinoid) in reducing both inflammatory and non-inflammatory acne lesions

True

84

Combination benzoyl peroxide and erythromycin therapy is more effective for acne than either drug alone

True (the activity of benzoyl peroxide is enhanced when used in combination with other medications including topical antibacterials)

85

For severe acne, the addition of once daily Adapalene/Benzoyl Peroxide to oral doxycycline 100mg reduced all types of lesions to a greater extent than doxycycline alone and the earlier onset of action with combination therapy correlated with a rapid reduction in P. acnes in the first 4 weeks

True (the activity of benzoyl peroxide is enhanced when used in combination with other medications including topical antibacterials)

86

Benzoyl peroxide may oxidise Tretinoin if applied simultaneously and it is recommended that benzoyl peroxide be used in the morning and Tretinoin at night

True (however an optimised, aqueous gel formulation of Tretinoin may be combined with benzoyl peroxide without the risk of peroxide-induced degradation of Tretinoin)

87

The main adverse effect of benzoyl peroxide is an irritant contact dermatitis

True

88

There is a rare potential for benzoyl peroxide to cause contact allergy

True

89

Benzoyl peroxide can bleach fabric, hair and other coloured materials

True

90

Benzoyl peroxide does not cause skin cancer

True

91

The 1% Clindamycin lotion is less irritating for acne than the alcohol-based solution and gel

True

92

Approximately 4-5% of topical Clindamycin is systemically absorbed

True

93

Clindamycin is effective against P. acnes although an increasing number of Clindamycin-resistant strains are associated with treatment failure

True

94

The main indication for topical Clindamycin is in acne vulgaris

True

95

Topical Clindamycin 1% as monotherapy is equally as effective as or superior to PO tetracycline for treating inflammatory lesions and BD 1% Clindamycin is as effective as minocycline 50mg BD

True

96

Combination therapy of Clindamycin in 1% with benzoyl peroxide, Adapalene (retinoid), Tretinoin (retinoid), salicylic acid is more effective than Clindamycin monotherapy

True

97

The addition of zinc acetate to topical Clindamycin reduces the systemic absorption of Clindamycin

True (usually approximately 3-5% of Clindamycin is systemically absorbed)

98

Mild local reactions from topical Clindamycin including itching, burning, stinging, excessive dryness, peeling, oily skin and erythema are usually due to the vehicle

True (contact allergy to Clindamycin is very rare)

99

Gram -Ve folliculitis has rarely been associated with topical Clindamycin use

True

100

There is no systemic absorption of topical erythromycin

True

101

One strategy to circumvent erythromycin-resistant P. acnes is to use a higher concentration of erythromycin with or without zinc

True (this strategy is effective in reducing erythromycin-resistant P. acnes)

102

Using topical erythromycin in combination with benzoyl peroxide is effective in reducing erythromycin-resistant P. acnes

True

103

The main indication for topical erythromycin is the treatment of acne vulgaris

True (available in a variety of vehicles in concentrations of 2% and 3%)

104

The role of zinc in topical erythromycin preparations is unclear as no statistical difference was found in the reduction of inflamed and non-inflamed lesions between topical erythromycin preparations with or without zinc

True

105

Topical erythromycin and benzoyl peroxide combination may be an alternative choice to topical metronidazole for treatment of pustulopapular Rosacea

True

106

Topical erythromycin has been associated with erythema, scaling, tenderness, burning, itching, irritation, oiliness and dryness

True

107

Topical erythromycin is a weak sensitiser and allergic contact dermatitis has been infrequently reported

True

108

There is a significant component of long-term acne benefit through topical erythromycin due to its anti-inflammatory effects

True

109

Systemic absorption of topical metronidazole is negligible

True

110

Topical metronidazole is NOT active against P. acnes or Demodex folliculorum

True (thus it seems unlikely that the beneficial effect of metronidazole for Rosacea stems from direct killing of the Demodex mite)

111

The mechanism of action of topical metronidazole for the treatment of Rosacea is uncertain, but metronidazole has anti-inflammatory effects that include suppression of cell-mediated immunity and leukocyte chemotaxis

True

112

The efficacy of topical metronidazole is enhanced by the addition of anti-inflammatory (subantimicrobial) doses of doxycycline

True

113

Topical metronidazole is effective against pustules, papules and to a lesser degree erythema; and is generally ineffective against telengiectasias and rhinophyma

True

114

It is unclear whether topical metronidazole has a role in treating acne vulgaris

True

115

Several studies have demonstrated that topical metronidazole can be used to eliminate the odour of putrid-smelling ulcers as well as ulcerated or fungating tumours where elimination of odour correlated with negative anaerobic cultures

True

116

Topical metronidazole has a very low potential for causing sensitisation although cross-reactivity to metronidazole has been reported in cases of contact allergy to tioconazole and isothiazolinones

True

117

Topical metronidazole adverse effects are rare and include dryness, itching, burning and stinging

True

118

The topical azelaic acid dose absorbed is about 3% and is higher with the 15% gel formulation (8% absorption) than that of the 20% cream (3% absorption)

True

119

Azelaic acid is indicated for the treatment of acne and reduces the concentration of P. acnes on the skin surface and follicles

True

120

Azelaic acid inhibits the division and differentiation of human keratinocytes, but does not reduce the rate of sebum production

True (although patients report gradual reduction in skin greasiness after 1-2 months of treatment)

121

Azelaic acid 15% gel BD for 15 weeks is superior to metronidazole gel in improving the inflammatory lesions and erythema of Rosacea

True

122

Azelaic acid has demonstrated promising results for the treatment of corticosteroid-induced perioral dermatitis and can be used in paediatric patients

True

123

Azelaic acid is useful for certain disorders of pigmentation as it has some activity against hypermelanosis caused by physical and chemical agents, post inflammatory hyperpigmentation, melasma

True

124

Azelaic acid is non-toxic

True

125

Azelaic acid is non-mutagenic

True

126

Azelaic acid is non-teratogenic

True

127

Azelaic acid has no systemic side effects

True

128

There are no cases of contact allergy to Azelaic acid

True

129

Up to 10% of patients commencing Azelaic acid may report itching, burning or scaling which may last up to 4 weeks

True (local reactions to Azelaic acid may be reduced by initiating treatment with once daily application rather than the usual BD application during the first 2 weeks of treatment)

130

Topical dapsone gel is FDA approved for the treatment of acne vulgaris

True

131

Systemic exposure to dapsone is 100 times lower for topical dapsone than for PO dapsone

True (and serum drug levels did not increase during 1 year exposure of topical dapsone)

132

Topical dapsone is effective with rapid onset of action for inflammatory acne lesions

True

133

The most commonly reported adverse effects with topical dapsone are transient dryness, erythema, rash or sunburn

True

134

There is no requirement for G6PD screening before starting topical dapsone or monitoring of haematologic parameters during treatment

True (no clinical signs and symptoms of haemolytic anaemia, no other changes in lab markers of haemolysis)

135

Common sodium sulfacetamide adverse effects include dryness and transient pruritus in over 50% of patients

True

136

When sodium sulfacetamide is combined with benzoyl peroxide, sulfacetamide produces an orange-brown discolouration which stains clothing and not skin

True

137

Antiseptics (Triclosan, Chlorhexidine, and Povidone-Iodine) are most commonly used for surgical skin sterilisation and for personal hygiene

True

138

Antiseptics (Triclosan, Chlorhexidine, and Povidone-Iodine) have a broad antimicrobial spectrum with low incidence of irritation or allergic contact dermatitis

True

139

Triclosan and Triclosan-based products have very low sensitising potential even when used on eczematised skin

True (primary antibacterial soap ingredient available today)

140

Chlorhexidine is primarily used as a surgical scrub

True

141

Chlorhexidine gluconate 2% washes + Mupirocin 2% ointment intranasally + PO rifampicin + PO doxycycline for 7 days is 74% effective in eradicating MRSA colonisation in hospitalised patients for at least 3 months

True

142

Pre-operative cleansing with Chlorhexidine-alcohol is more effective than povidone-iodine in preventing superficial and deep incisional infections within the first 30 days after surgery

True

143

Allergic contact dermatitis due to Chlorhexidine is rare but sensitisation to Chlorhexidine has been reported in children with atopic dermatitis

True

144

More than 50 Anaphylaxis from Chlorhexidine has occurred but only 2 cases have resulted in application to intact skin

True

145

When using Chlorhexidine for skin sterilisation near the ear it is prudent to ensure that none of the disinfectant trickles into the ear canal as Chlorhexidine has been associated with ototoxicity resulting in deafness

True

146

Povidone-iodine is primarily used as a surgical scrub

True

147

Povidone-iodine is an antimicrobial agent active against gram +Ve and gram -Ve bacteria

True

148

Povidone-iodine is commonly used as an antiseptic perioperatively and for skin wounds

True (active ingredient in betadine solution)

149

The incidence of allergic contact dermatitis in Povidone-iodine is rare

True (more associated wth irritant contact dermatitis)

150

Povidone-iodine is associated with irritant contact dermatitis

True