Topical Antibacterials Chapter 36

shevyatiwari's version from 2015-10-17 08:29


Question Answer
A polypeptide antibacterialT
Complexed with Zn for broad spectrum activityF, to increase shelf life from 2-5 years. Also makes it less water soluble
Cat CT
Active against GN and pseudomonas, nocardia, enterobacteriacae, candida and cryptococcus F. Active against staph
Very effective in mono therapy for eliminating S aureus carriageF, minimally effective (44% eradication rate)
Bacitracin is superior to white petrolatum in dermatologic surgeryF, should treat with white petrolatum
Common allergen for contact dermatitis T
Anaphylaxis can occurT
Can cross react with neomycin allergyF, co-reacts, doesn't cross react. Patch testing to both may uncover neomycin allergy
Often combined with mupirocinF, often combined with polymyxin B/neomycin

Polymyxin B

Question Answer
Anionic branched cyclic decapeptideF, cationic
Destroys bacterial membranes by a surface detergent like mechanismT
Can be given topical or POF,topical, IV, IM
Cat CF, B. Polymyxin B = Cat B
Active against GN including pseudomonasT
Active against fungiF
Triple therapy includes polymyxin B, neomycin and bacitracinT
Active against GP onlyF, N, incl psuedomonas, proteus, serratia and acinetobacter. Not effective for GP or fungi
Useful as monotherapyF, combined with others to increase GN cover
Contact allergy is commonF, rare


Question Answer
An aminoglycosideT
Binds to 50s subunit of bacterial ribosomeF, 30s
Potentiates bacterial DNA polymeraseF, inhibits
Cat CF, D
Good cover incl pseudomonas, and anaerobes such as bactericidesF, cover doesn't include these
Resistance is very rareF, common - therefore usually used in combination
Bacitracin, neomycin and polymyxin B are used together oftenT
Cross reacts with streptomycin, kanamycin, gentamicin, paromomycin, spectinomycin, tobramycinT
Can be nephrotoxic and ototoxicT


Question Answer
Mupirocin inhibits bacterial RNA protein cell wall synthesisT
BacteriostaticF, cidal
Topical absorption is significantF, minimal
Active against P acnes, and enterococciF
Equivalent to erythromycin in imeptigoT, FDA approved for this as well
Most S/E are due to the vehicle - polyethylene glycolT
Doesn't cross react with other antibacterialsT
Common cause of ACDF
Nasal formulation contains WSPT
Cream contains polyethylene glycolT
Cat BT
Resistance is mostly seen in VREF, in MRSA
Mupirocin is more costly than erythromycinT, however cost is offset by reduced adverse effects
Nasal formulation is more irritating than creamF, is an ointment, the polyethylene glycol is the most irritating


Question Answer
BactericidalF, static
Binds to 50S ribosomal subunitT
Inhibits ribosomal peptidyl transferaseT
Prevents translation by blocking feet-trna to P site of ribosomseT
Cat CF, B
GP activity, and most anaerobessT
No siginficant cross reactionsT
Approved for impetigo secondary to MRSAF, only for MSSA
ACD is a new problemT


Question Answer
Binds to 30S subunitst
Bactericidal for GP and some GN incl psuedomonasT
Bactericidal for strepF
ACD is rareT
Significant cross reactivityT
Cross reacts to prior exposure to systemic aminoglycosides including neomycinT

Silver sulfadiazine

Question Answer
Bactericidal for GP, and GN incl MRSA and pseudomonasT
binds to bacterial DNA and inhibits replicationT
Cat CF, B
Adverse effects incl ACD, haemolysis in G6PD deficiency, hyperosmolality, methaemoglobinemiaT
Hepatic failure associated with prolonged useF, renal insufficiency
Argyria can occur T
Significant absorption causes renal insufficiencyT


Question Answer
Cat CT
Activity against pseudomonas and dermatohpytesT
C/I in those with hypersensitivity to iodine,T
Neurotoxicity, iododerma, goitre and interference with thyroid tests is possibleT
History of treatment in amoebiasisT
Mechanism of action unknownT
Active against P acnes, MRSA, pseudomonasT
Broad spectrum agentT
Not useful in fungal infections complicated by bacterial involvementF, are useful

Benzyl Peroxide

Question Answer
Broad spectrum antibacterialT
Oxidising activityT
Indicated for mild to moderate acneT
Bacteriostatic for P acnes, inhibtis TG hydrolysis, reduces inflammationF, bactericidal
Stability dependent on vehicleT
Most stable in propylene glycolF, least
Systemic absorption is 95%F, 5%
Drug is metabolised in the skin to benzoic acidT
More effective on inflamed lesions cf non-inflamed lesions cf erythromycin or clindamycinF, more effective on non inflamed lesions
Better than tretinoin for inflammatory lesionsT
BP and tretinoin should be applied togetherF, BP can oxidise tretinoin
Adapalene causes more irritation and dryness than either of its componentsT
Keratolytic but not comedolyticF, both keratolytic and comedolytic
Systemically absorbed BP is excreted by the kidneysT
Cat CT
Useful for controlling antibiotic resistance of P acnes to erythromycin, tetracycline and clindamycinT
As effective as erythromycin or clindamycin on pustules and papulesT, the inflammatory lesions
As effective as erythromycin or clindamycin on non inflammatory lesionsF, more effective
As effective as tretinoin in non inflammatory lesionsT
As effective as tretinoin in inflammatory lesionsF, more effective


Question Answer
Lotion is less irritating than the gelT
Approx 95% systemically absorbedF, 5%
Cat CF, B CAN use Clindatech on Pregnant ladies - also can use Erythromycin and azalaic acid
Broad spectrum antibacterial, binds to 50S subunitt
Effective against GP, GN and anaerobesT
Resistasnce is a problemT
Contact allergy is commonF, rare
GN folliculitis can occurT
Psuedomembranous colitis can occurT


Question Answer
Cat CF, B
Liposomal formulation is more effective than conventional and hydroalcoholicT
BacteriostaticF, cidal
The addition of Zn prolongs shelf lifeF, reduces rates of resistance to P acnes
Benzyl peroxide and erythromycin are C/IF, BP can help reduce rates of resistance against P acnes
Strong inducer of ACDF, weak
Concentrations available are between 1-4%T
Rates of resistance are approx 25%T
Zn, increased concentration of erythromycin and BP may be useful in managing resistanceT
No data on systemic absorptionT


Question Answer
Reduction products result in DNA disruption and inhibition of nucleic acid synthesisT
Cat CF, B
Broad spectrum of activityF, anaerobes
Active against P acnesF
Cross reacts with tioconazole and isothiazolinonesT
Neglible systemic absorptionT
Active against most anaerobic bacteria and protozoaT
Active against P acnesF
Active against staph, strep, fungiF
Active against DemodexF
Suppresses humoral immunityF, cell mediated
Suppresses leukocyte chemotaxisT
Useful in vascular rosaceaF
As effective as PO tetracyclineT
Can eliminate odour of ulcers or ulcerated/fungating tumoursT
Reduces pain and discharge in peri anal Crohn'sT
Useful in seb derm at higher dosesT (1%)
Cross reacts with tioconazole and isothiazolinonesT

Azelaic acid

Question Answer
SyntheticF, naturally occurring
Competitive inhibitor of tyrosinaseT, possible use in pigmentary disorders
Suppresses UVB induced expression of IL1B, IL6, TNFa and PPARYT
No systemic absorptionF, approx 3%
Cream has higher systemic absorption than gelF, gel is 8%, cream 3%
Cat BT
BactericidalF, static
Activity against P acnes and candidaT
Low pH favours uptake into cellsT
Reduces rate of sebum productionF
Improvement detected in 4 monthsF, 1-2 months, maximal improvement at 4 months
Has depigmenting ability on freckles, lentigines, pigmented Seb K and naveiF
Has depigmenting ability on hyeprmelanosis, post inflammatory hype pigmentation, lentigo malignant melanomaT
Non toxic, non mutagenic, non teratogenicT
Is a potential energy substrateT
Contact allergy is commonF, no reported cases
10% report itching, burning or scaling which lasts up to 4 weeksT
Tricarboxylic acidF, dicarboxylic acid
Inhibits division and differentiation of keratinocytesT

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