|
Antibiotic usage in dermatology
David S Feingold, MD
Department of Dermatology and Medicine, Tufts University School of Medicine and New England Medical Center, Boston,
Massachusetts, USA
Our ability to diagnose and treat diseases of all organ systems has progressed beyond even our most optimistic
predictions of 50 years ago, and our understanding of human pathophysiology continues to make enormous advances.
Unfortunately, however, our ability to treat bacterial pathogens with antibiotics has suffered enormous setbacks
since the introduction of these drugs. In 1950, the antibiotic arsenal included penicillin, streptomycin and sulfonamides,
followed by tetracyclines, chloramphenicol and erythromycin. Today, bacterial resistance has compromised the effectiveness
of these antimicrobials. Until the last decade the development of new antibiotics has roughly kept pace with the
continuing evolution of bacterial resistance to antimicrobials. Today, the problem of resistance has become far
more serious, escalating to crisis proportions.
Antibiotic misuse is a major contributor to bacterial resistance.
It has also been conclusively demonstrated that a decrease in the use of an antibiotic in a community may result
in a decrease in the percentage of resistant pathogens in that community.(1) Dermatologists rely heavily on antibiotics
to treat their patents for a variety of conditions; thus, it seems clear that policies and programs to foster the
judicious use of antibiotics must be endorsed. These are common conditions for which dermatologists prescribe antibiotics
(Table 1), and where actions toward optimizing the use of these agents can be suggested.
Prophylactic use
Antibiotics are often prescribed for prophylaxis after cutaneous trauma or surgical wounds. Studies to prove antibiotics
helpful in these clinical situations are difficult to conduct. There are, however, some prudent guidelines. When
feasible, topical antimicrobials are preferred over systemic agents. This should be a general principle of dermatological
antibiotic use, because topical application exposes only the sparse cutaneous bacterial flora to the agent, whereas
systemic use causes all of the floral sites, including gastrointestinal, respiratory and genital, to undergo selection
pressure for the development of resistance. Also, antibiotics, whether topical or systemic, should only be used
as prophylaxis for wounds that have a significant likelihood of infection. Examples would include traumatic wounds
in the tropics, where there is a high incidence of secondary infection, or surgical wounds in a “dirty” site. Antibiotic
treatment should be directed toward the most likely pathogens rather than all potential organisms. Topical mupirocin,
for example, with its narrow gram-positive spectrum, is a preferred agent for cuts or scratches incurred in the
summer heat; prophylaxis for surgical wounds is best aimed at preventing staphylococcal and streptococcal infections,
rather than a broader spectrum of organisms.
Clinical applications
Impetigo is a superficial cutaneous infection by Staphylococcus aureus or Streptococcus pyogenes. Although usually
a self-limited infection, most dermatologists treat minimal impetigo with a topical antibiotic. Extensive cases
are treated with several days of a systemic antibiotic directed at Gram-positive cocci. Erysipelas and cellulitis
are usually acute, potentially dangerous S. pyogenes infections of the dermis and subcutaneous tissue. Systemic
therapy with a beta-lactam antibiotic is the optimal treatment. Bacterial folliculitis is most often a S. aureus
infection of hair follicles which, when persistent, deserves topical or systemic anti-staphylococcal therapy, depending
on the extent of infection. Furuncles and abscesses, and cutaneous purulent collections are best treated by drainage
alone, where appropriate. Antibiotic treatment, although frequently given, is only indicated if there is significant
associated cellulitis.
Patients with acute flares of atopic dermatitis or other types of
eczema often respond more promptly to therapy if antibiotic treatment aimed at staphylococci and streptococci is
part of the regimen. The rationale is that the gram-positive pathogens are often present in large numbers in dermatitic
skin. Heavy colonization contributes to inflammation by causing toxin-mediated or superantigen-mediated release
of cytokines and other inflammatory mediators. Decreasing the bacterial colonization results in decreased inflammation.
Empiric antibiotic treatment might be recommended for all patients with severe inflammatory dermatoses. Topical
antibiotics may be employed if the process is limited; systemic treatment is necessary to treat extensive inflammatory
dermatoses.
Treating acne and rosacea
Acne vulgaris is an extremely common clinical condition in adolescents and young adults, for which dermatologists
rely heavily on antibiotics. The pathology of acne involves the pilosebaceous follicle in the skin. Abnormal follicular
keratinization and increased sebum production results both in comedone formation and overgrowth of Proprionibacterium
acnes, which results in inflammation. Antibiotic therapy has a direct anti-inflammatory action, as well as reducing
P. acnes counts in the follicles. Therapy with these drugs is typically recommended for patients with inflammatory
acne, often intermittently or continuously, throughout the disease’s usual natural history of 8-12 years. In cases
of mild inflammatory acne, topical antibiotics are used initially. Erythromycin and clindamycin are the common
agents prescribed. More severe cases require treatment with oral antibiotics, often continued for years. The tetracyclines
(i.e., tetracycline, doxycycline, minocycline), erythromycin and, to a lesser extent, clindamycin and sulfa-trimethoprim,
are the oral antibiotics more typically used.
Chronic use of topical agents can lead to the development of resistant
P. acnes and staphylococci.(2,3) Multi-resistance in these organisms has also been demonstrated, although studies
show that the development of resistance to topically-applied erythromycin is decreased by the concomitant application
of benzoyl peroxide.(2,3) Resistance has been shown to emerge in the skin flora of household contacts of patients
treated with topical antibiotics.(4) Systemic use of antibiotics markedly amplifies resistance because of the increased
number of bacteria exposed to selection pressures.
Alternative treatment regimens that do not rely on the use of antibiotics
have proven to be effective therapy for acne. Several non-antibiotic regimens attack the abnormal keratinization
and sebum production. The synthetic retinoids, both topical and systemic, are effective anti-acne agents, with
their action directed at normalizing follicular keratinization. In the female patient, a variety of anti-androgen
therapies, both topical and systemic, have been used effectively to suppress sebum synthesis.(5,6) These include
estrogen, which suppresses ovarian androgen synthesis, glucocorticoids, which suppress adrenal androgen synthesis,
and spironolactone which blocks androgen receptors in the skin.
Rosacea is a chronic, inflammatory dermatosis that involves the
face with erythema and an intermittent acneiform eruption. Typical therapy is topical or oral antibiotics, the
same ones used to treat acne vulgaris. A recent major textbook of dermatology stated that therapy must be maintained
indefinitely, since relapses are common following discontinuation of therapy.(7) Several authors have presented
treatment plans to minimize oral antibiotic use in rosacea. These should be codified into a single or a few suggested
plans, and disseminated throughout the specialty.
In general, authoritative guidelines, which reduce to a minimum
the systemic use of antibiotics, should be promulgated for the treatment of acne and other dermatological conditions.
Topical antibiotics are preferred, but should be used in a way that minimizes exposure to selection pressures for
resistance. In order to change prescribing habits, dermatologists must be convinced that overuse of antibiotics
is a serious problem in their field, and that regimens using less of these drugs will not adversely effect patient
care. Such efforts must become a priority within the specialty if we are to serve the interests of the coming generations.
References
- Seppälä H, et al. 1997. New Eng J Med 337:441-446.
- Harkaway, KS, et al. 1992. Br J Dermatol 126:586-590.
- Eady EA, et al. 1996. Br J Dermatol 134:107-113.
- Eady EA, Cove JH, Holland KT, Cunliffe WJ. 1990. Br
J Dermatol 122: 233-244.
- Beylot C, et al. 1998. Dermatol196:148-152.
- Schmidt D. 1998. Dermatol 196:153-157.
- Pollack SV. Rosacea. 1996. In Cutaneous Medicine and
Surgery, edited by KA Arndt et al. Philadelphia, PA: WB Saunders, p. 488.
|
