Management of Skin and Soft-Tissue Infection

doi:10.1056/NEJMclde0708359

A 20-year-old college basketball player presents to the emergencydepartment with a 2-day history of a red, painful area on hisright buttock. He reports that there was no specific traumato this area but that he had participated in several basketballgames over the past several weeks at various schools throughoutthe United States. He believes he may have had a low-grade feverthe night before but did not take his temperature. He has nochronic medical conditions and is taking no medications. Hedid receive amoxicillin for 1 week within the past year fora sinus infection but otherwise has not received any antimicrobialtherapy. He has no known allergies to medication. A physicalexamination was notable for an oral temperature of 37.7°C,a pulse of 78 beats per minute, a blood pressure of 110/70 mmHg, respirations of 12 per minute, and an erythematous, warm,tender, 5-by-3-cm area on the right buttock, with a firm, tendercentral area approximately 2 cm in diameter and without drainage.He does not like to take medications, but he is concerned thathe will not be at full strength for his next basketball gamein 1 week's time.

What kind of treatment would you find most appropriate for thispatient? Three options are outlined and each is defended ina short essay by an expert in the management of infectious diseases;read the essays and then cast your vote.

Treatment Option 1

Incision and Drainage Alone

Henry F. Chambers, M.D.

This is a case of an uncomplicated cutaneous abscess, probablydue to infection with Staphylococcus aureus, in a college athlete.On physical examination, the center of the lesion is indurated,not fluctuant, maybe because the abscess is not fully matureor because overlying inflammation and tissue edema are obscuringa deeper abscess. The absence of purulent drainage, which ifpresent would favor the diagnosis of abscess, is not helpfulin ruling out the diagnosis. Needle aspiration or ultrasonographyis useful in locating the collection of pus not evident on inspectionor palpation. Surrounding cellulitis is common, and given thefocal nature of this lesion, it can be effectively treated withincision and drainage alone. Prescribing a course of antimicrobialtherapy, although a common practice, is unnecessary and maybe associated with side effects, either in direct relation tothe use of the medication or through facilitation of resistantorganisms. Antibiotics have not been shown to improve outcomesin patients with uncomplicated abscesses, as compared with incisionand drainage alone.

The fact that antibiotics are not necessary in treating uncomplicatedstaphylococcal skin infections was suggested by the resultsof a trial published in 1957 comparing intramuscular penicillinwith oral penicillin for a variety of skin infections, 80% ofwhich were boils, abscesses, or carbuncles.¹ Clinical isolatesof S. aureus from 66 of the 239 patients were penicillin-resistant,yet these patients fared just as well as those infected withsusceptible strains. The following year, Anderson reported resultsfor 320 patients with S. aureus infections in the hand thatwere treated with the use of surgical drainage.² The outcomewas the same for those not treated with penicillin and thosetreated with penicillin. These findings have been confirmedin randomized trials comparing no antibiotic therapy and therapywith cloxacillin,³ clindamycin,⁴ or cephradine.⁵

Should the treatment recommendations be different for this athleteif his infection is caused by a community-associated strainof methicillin-resistant S. aureus (MRSA)? Although there areno specific risk factors for MRSA in this case, community-associatedMRSA strains are widespread and prevalent throughout the UnitedStates.⁶ Regardless of susceptibility, antibiotics are not neededin this healthy man with an uncomplicated first abscess, nocoexisting medical conditions, and no systemic signs of infection.According to three observational studies⁶^,⁷^,⁸ and one randomizedtrial,⁹ the outcome for MRSA infection of the skin and softtissues is independent of whether the antibiotic prescribedis active or not, and outcome of MRSA infections treated withan inactive agent is the same as that for methicillin-susceptibleS. aureus (MSSA) infection treated with an active antibiotic.One retrospective study¹⁰ suggesting a benefit of antibioticsis not applicable to this particular case. The patient populationstudied had a high rate of coexisting medical conditions; 34%of patients had health care–associated infections, and34% were hospitalized.

A randomized, double-blind trial¹¹ comparing placebo to cephalexinin 166 patients undergoing surgical drainage of uncomplicatedabscesses provides the strongest evidence yet that antibioticsare not needed. A total of 68% of cultures yielded S. aureusstrains, 88% of which were MRSA, and 94% of the MRSA strainswere positive for Panton–Valentine leukocidin. In all,90.5% of placebo recipients had a clinical cure, as comparedwith 84.1% of cephalexin recipients — an absolute differenceof 6.4% (95% confidence interval, –4.2 to 17.0), favoringthe placebo.

I anticipate an excellent outcome in our college athlete withthe use of incision and drainage alone. I would not want toexpose him to potential side effects from the use of antibiotics,although they are uncommon, without a reasonable likelihoodof benefit.

Dr. Chambers reports receiving grant support from Cubist andJohnson and Johnson. No other potential conflict of interestrelevant to this article was reported.

From the Department of Medicine, Division of Infectious Diseases,University of California, San Francisco, San Francisco.

Treatment Option 2

Incision and Drainage plus Anti-MSSA Therapy

Robert C. Moellering, Jr., M.D.

There are three major issues to consider in determining whetheror not incision and drainage plus therapy with an oral antistaphylococcalagent such as dicloxacillin or an oral first-generation cephalosporinsuch as cephalexin should be used in this patient. The issuesto be considered are the following:

1. What is the potential benefit of antimicrobial therapy aftersuccessful incision and drainage in this patient?

2. What is the probable cause of the infection of the buttockin this patient?

3. What are the probable patterns of susceptibility of the pathogenscausing this infection in the geographic area in which it occurred?

It has been clearly shown that many localized small abscessesand furuncles will respond favorably to local incision and drainagealone and do not require antimicrobial therapy. Indeed, a recentstudy of such infections in the San Francisco area showed thatcephalexin was no better than placebo for treating such infections.¹¹It should be noted, however, that the majority of these infectionswere due to community-associated methicillin-resistant Staphylococcusaureus (MRSA), and in essence the study had a double-placebodesign, since cephalexin is not active against community-associatedMRSA.

However, in patients with a sizable area of surrounding cellulitisor with skin and soft-tissue infections in which there is cellulitiswithout a drainable focus, most clinicians would add antimicrobialagents to the therapeutic regimen.¹²^,¹³ Antimicrobial drugsare used in these patients to provide more rapid resolutionof symptoms, to prevent further spread of the infection, andto prevent bacteremia with dissemination to other parts of thebody. The prevalence of bacteremia in uncomplicated skin andskin-structure infections is generally less than 5%.¹²^,¹⁴ However,certain factors have been shown to be associated with bacteremia,including the absence of previous antimicrobial therapy, acuteand abrupt onset of cellulitis, illness of less than 2 days'duration, presence of two or more coexisting conditions, andinvolvement of a proximal limb.¹⁵

Most uncomplicated skin and soft-tissue infections in immunocompetenthosts are caused by group A streptococci or methicillin-susceptibleS. aureus (MSSA).¹²^,¹³ Group A and other β-hemolytic streptococciremain universally susceptible to penicillins and cephalosporins(including penicillin G), the antistaphylococcal penicillins,and the oral cephalosporins. These agents are also more activeagainst group A streptococci than the tetracyclines or trimethoprim–sulfamethoxazole,which are frequently used for presumed community-associatedMRSA infections.¹⁶^,¹⁷

During the past decade, community-associated MRSA has becomeincreasingly frequent in the United States, and in certain communities,as many as 60 to 75% of S. aureus isolates are now resistantto methicillin.¹⁸^,¹⁹ Such isolates are also being seen withincreasing frequency in Australia and in parts of Europe, butin many parts of the world their prevalence is low or nonexistent.In communities without a high prevalence of community-associatedMRSA, initial treatment of skin and soft-tissue infection withincision and drainage and use of an oral antistaphylococcalpenicillin or cephalosporin is perfectly reasonable, is desirablegiven the potential for streptococcal infection, and is consistentwith current therapeutic guidelines.¹²^,¹³ Given the rapid spreadof community-associated MRSA, it is imperative to obtain materialfor culture and susceptibility testing when possible and tokeep track of local variations in the prevalence of MRSA inthe community.

The patient in the vignette does not have evidence of feveror clinically significant systemic reaction to the infectionon his buttock and is not known to have had exposure to community-associatedMRSA. Nonetheless, given the amount of the surrounding cellulitis,it is perfectly reasonable to add an antimicrobial agent tothe therapeutic regimen. Unless the cultures are positive forMRSA, use of either dicloxacillin or cephalexin is appropriate.

Dr. Moellering reports receiving consulting or advisory feesfrom Pfizer, Cubist, Astellas, Forest, and Wyeth. No other potentialconflict of interest relevant to this article was reported.

From Harvard Medical School and the Department of Medicine,Beth Israel Deaconess Medical Center — both in Boston.

Treatment Option 3

Incision and Drainage plus Anti-MRSA Therapy

Paul Kamitsuka, M.D., D.T.M.H.

First, although decisions regarding the choice of empiricalantibiotics should be made on the basis of local resistancedata when possible, the likelihood that our patient has a community-associatedmethicillin-resistant Staphylococcus aureus (MRSA) infectionis considerable. He is an athlete with exposure to skin florathrough physical contact in geographic locales across the UnitedStates. In a study of acute skin and soft-tissue infectionsin patients presenting to emergency departments in 11 U.S. cities,59% of the infections were due to community-associated MRSA(range, 15 to 74).⁶ Nonetheless, it is advisable to obtain asample for culture at the time of incision and drainage, notonly to focus current treatment but also to have susceptibilitydata in case the infection recurs and eradication of community-associatedMRSA is needed.

Second, although it has long been accepted that most MRSA soft-tissueabscesses may be treated with incision and drainage alone,¹³recent data suggest that antibiotics may play a more importantrole in treating abscesses due to community-associated MRSA.Unlike traditional MRSA strains,²⁰ community-associated MRSAstrains often produce Panton–Valentine leukocidin, a pore-formingcytotoxin associated with increased tissue destruction. In aretrospective cohort study of 492 adults with 531 independentepisodes of skin and soft-tissue infections with community-associatedMRSA, most of whom underwent incision and drainage, therapywas successful in 95% of those receiving an active antibioticas compared with 87% of those who did not.¹⁰ Use of an inactiveantimicrobial agent was an independent predictor of treatmentfailure on logistic-regression analysis (adjusted odds ratio,2.80; 95% confidence interval, 1.26 to 6.22; P=0.01). Szumowskiet al.²¹ found, in a retrospective review of 399 sequentialcases of culture-confirmed S. aureus skin and soft-tissue infections,including 227 cases of MRSA infection, use of an antibioticto which the isolate was sensitive was associated with an increasedlikelihood of clinical resolution (odds ratio, 5.91, as comparedwith no such use), after adjustment for incision and drainageand human immunodeficiency virus status. Finally, in a prospectiveobservational study of a pediatric population, Lee et al.⁸ foundthat an infected site more than 5 cm in diameter treated bymeans of incision and drainage was less likely to respond inthe absence of effective antibiotic therapy than with such therapy.Our patient's abscess is 5 cm in diameter.

A third consideration is whether providing effective antibioticswill decrease the risk of persistent carriage and thereby preventrecurrent infection as well as spread of community-associatedMRSA to others. The answer to this question awaits further study,although in the absence of hard data clinicians often find themselvesattempting to break the cycle of recurrent infection with thecombined use of systemic antibiotics and topical antiseptics.Recurrent skin and soft-tissue infection is a vexing characteristicof community-associated MRSA, with estimates of recurrence rangingfrom 10%²² to 23.8%.²¹ Although some of these recurrences maybe due to infection with a different community-associated MRSAstrain, others result from persistent cutaneous carriage ofthe original strain after resolution of the initial infection.The spread of community-associated MRSA to household contactsis also problematic. Zafar et al.²³ found that 20% of householdcontacts of patients with community-associated MRSA skin andsoft-tissue infections carried MRSA, with half the MRSA strainsrelated to the patient's infective isolate. A previous studyreported household MRSA-carriage rates of 14.5%.²⁴ Anecdotalevidence suggests that more than 60% of households of childrenhospitalized with community-associated MRSA infections includeone or more family members who had a putative MRSA infectionin the previous 6 months.²² The likelihood of clinical infectionafter colonization by community-associated MRSA appears to beconsiderable. Ellis et al.,²⁵ in a prospective observationalstudy of soldiers, found that soft-tissue infections developedover a period of 8 to 10 weeks in 9 of 24 (38%) of those withcommunity-associated MRSA in their nares, as compared with only8 of 229 (3%) of those with nasal carriage of methicillin-susceptibleS. aureus (MSSA) (P<0.001).

For our athlete, eager to resolve his infection before nextweek's game, the provision of an antibiotic effective againstcommunity-associated MRSA, perhaps with the use of 2% chlorhexidinefor bathing, appears to be prudent.

No potential conflict of interest relevant to this article wasreported.

From Wilmington Health Associates and the Department of Medicine,University of North Carolina School of Medicine, Wilmington.

Given your knowledge of the condition and the points made bythe experts, which treatment option would you choose? Base youropinion on the published literature, your past experience, recentguidelines, and other sources of information, as appropriate.Indicate your choice by using the Cast Your Vote button below.You may also submit comments after you vote (maximum of 175words).