In the Disease Control Priorities (DCP) analysis of treatment efficacy, 727 studies of treatments for pyoderma were evaluated in the context of management of pyodermas in a tropical and resource-poor environment (16). Of these, many were rated as effective preventive therapies using systematic reviews of the current literature: chlorhexidine solution, hexachlorophene scrubbing, and neomycin/polymyxin B-bacitracin (Neosporin) cream. In the case of primary treatments, effectiveness was reported with the following topical therapies: povidone iodine solution, hydrogen peroxide cream, electrolyzed strong acid aqueous solution, tea tree ointment, soframycin ointment, honey, fusidic acid cream, trimethoprim-polymyxin B sulfate cream, rifaximin cream, sulconazole cream, miconazole cream, neomycin/Polymyxin B-bacitracin (Neosporin) cream, and mupirocin, as well as some systemic antibiotics, cephalexin, erythromycin, penicillin, augmentin, amoxicillin, sultamicillin, (di)cloxacillin, azithromycin, cefadroxil, cefpodoxime, cefaclor, ceftizoxime, clindamycin, erythromycin, clarithromycin, tetracycline, fluoroquinolones, and fusidic acid. The Cochrane review (48) of impetigo included fewer studies and used stringent criteria. It found that there was no difference between the topical agents such as mupirocin and fusidic acid, and that penicillin was less effective than most other antibiotics such as erythromycin and cloxacillin. However, although it commented on resistance patterns, these were not specifically documented in the studies. Interestingly, most topical agents – the most comprehensive studies were with mupirocin and fusidic acid – were equal to or more effective that oral antibiotics. Likewise, the review rejected most of the studies using antiseptics either because they were underpowered or there was no placebo arm.

The standard treatments for superficial bacterial infections of the skin such as impetigo are limited in most developing countries through cost. Having said this, the best evaluated topical preparations are these specific antibacterial, such as fusidic acid ointment, mupirocin, or retapulin ointment, which are given daily for up to 7–10 days (49,50). These agents have been tested more against staphylococcal than streptococcal infections; nonetheless, efficacy is confirmed. Recent studies of these agents add more information. For instance, a recent study of fusidic acid compared with placebo in a general practice setting, with both groups using povidone iodine foam (51), showed a cure rate of 56% after 1 week of treatment for fusidic acid ointment, but only 13% for povidone iodine alone. It is interesting that in this community-based study, no S. aureus isolates were resistant to fusidic acid. Yet other studies in Norway (52) and Guyana (53) found that 75% and 42%, respectively, of S. aureus strains were resistant to fusidic acid. Over 60% of isolates in the Guyanan study were S. aureus. Mupirocin was originally formulated in an ointment base, and a new cream formulation evaluated in experimental infections showed similar efficacy to fusidic acid (54). Most recent studies comparing mupirocin with erythromycin have found advantages in using mupirocin in view of the wide spread of erythromycin resistance (55). The new agent, retapulin, is also very effective after 1 week of treatment in impetigo (56,57). It has similar efficacy to fusidic acid ointment, but in addition, clears S. aureus resistant to fusidic acid or muprirocin. So treatment with topical antibacterials, such as fusidic acid, retapulin, or mupirocin, is effective, but the disadvantage of these topical agents in a tropical environment is that they are expensive. The use of cheaper agents such as antiseptics is a necessary option, even though the evidence base for their evaluation is thin.

Chlorhexidine, clioquinol, potassium permanganate, and povidone iodine have all been used to treat impetigo and are said to be clinically effective, but there is insufficient stringent trial evidence of their value (3,48). Likewise, gentian violet at concentrations of 0.5–1% is a cheap preparation that is widely used, with proven in vitro efficacy against agents commonly involved in pyoderma (58). Again, the difficulty in evaluating this agent is that there is little robust clinical trial data (59). Most of these compounds have also been used to prevent infections. In many rural pharmacies, tetracycline ointment is still available and is widely used for the treatment of superficial skin lesions, even though some bacterial infections will be unresponsive. There is one recent study using topical tetracycline ointment from Japan that showed that it was as effective as a combination of the same ointment and erythromycin; there was no mention of drug resistance in this community (60). Topical neomycin, as well as bacitracin, is also widely available, but associated with identifiable levels of treatment failure, as well as carrying a risk of sensitization or adverse effects.

Community-applied measures have not been evaluated thoroughly in the management of skin infections, although there is data to show that effective treatment of scabies with ivermectin reduces the frequency or streptococcal pyoderma and serious consequences such as hematuria (39). Provision of supplies of medication is a means of achieving reduced incidence of disease at community level; for instance, Scmeller et al. reported the impact of provision of simple remedies on the incidence of infective skin diseases (61). Yet they showed that prevalence of bacterial infections was only reduced from 12.7% to 11.3% through provision of 1% gentian violet solution.

As stated previously, there is a real shortage of other studies on topical therapies for pyoderma, although there is evidence that there are alternatives such as zinc pyrithione (62). Most recent evaluations of antiseptics have focused on their use as agents to prevent positive blood cultures after insertion of intravenous devices or during surgery. Povidone iodine is effective for this purpose, but when it is given over larger areas of body surface, it can be absorbed, causing transient rises of blood iodine levels (63).

The prevention of pyoderma using chemotherapy is a more difficult target, and in the longer term, ambitious programs such as the development of a streptococcal vaccine are in development. However, there are simpler methods. A small study of antibacterial soap in Karachi containing triclocarban showed that its use reduced the frequency of impetigo by at least 40% (64). When a plain soap arm was introduced, it was found that introduction and promotion of hand washing and body washing with plain soap could also reduce the risk of impetigo (65); hand washing also reduced the risk of diarrheal disease.

A range of oral antibiotics are effective in eradicating bacterial skin infection. For instance, Group A streptococci are still sensitive to penicillin, which can be used for treatment, with alternatives for staphylococcal infections being cloxacillin, flucloxacillin, and erythromycin. At present, methicillin resistance among staphylococci is largely regarded in industrialized countries as a nosocomial problem; yet it has now spread to the community, and skin infections provide an ideal medium for spread of resistance even in developing countries. S. aureus strains isolated from skin sites, even in remote tropical areas, may now be resistant to βlactam penicillins and tetracyclines through spread of resistance genes. However, unfortunately, the spread of microbial resistance has only been evaluated in a few instances.

The treatment of pyodermas in a tropical setting presents us with a dilemma, as affordable treatments generally do not have a strong evidence base to support their use and there is also little data on antimicrobial resistance in this environment. The recent evaluation of childhood skin infections in the developing world published by the World Health Organization (66) states that “there is no specific recommendation for the treatment of pyoderma in tropical areas, where the bacteriological profile is somewhat unclear, although beta-haemolytic streptococcus (BHS) seems to predominate in many areas, and

where access to expensive drugs may be difficult.” The guidance recommends the use of oral agents appropriate to the likely spectrum of bacteriological disease although, once again, re-affirming the lack of recent studies. It also states that although there is widespread experience of the use of benzathine penicillin, it does not recommend its use. In many cases, this brings us back to dependence on sensible guidelines derived for local communities. The recommendations for treatment in Mali, as part of the algorithm study that targeted pyoderma as one of the key diseases (13), propose that antiseptics treatment (10% polyvidone iodide or 1/10,000 potassium permanganate) should be used for 1 week. But in severe cases or after failure of topical treatment, it was recommended that oral antibiotics (erythromycin or amoxicillin) should be given for 1 week in addition to antiseptics.

【节选自Hay RJ. Scabies and pyodermas – diagnosis and treatment. Dermatologic Therapy. Volume 22, Issue 6, pages 466–474, November/December 2009】