Skin Infections in Athletes

Brian B Adams

Disclosures

Expert Rev Dermatol. 2010;5(5):567-577. 

In This Article

Bacterial Infections

Methicillin-resistant Staphylococcus aureus (MRSA) infection creates extensive attention in the media. S. aureus (methicillin-resistant or -sensitive) causes multiple types of cutaneous infections, each of which possesses a different clinical appearance.[25] No staphylococcal infection has morphologic traits specific to a particular strain of S. aureus. A clinician would only determine the resistant variety after culturing the organism. Interestingly, the recent reports indicate that community-acquired MRSA may derive its occasional aggressive presentation from the presence of the Panton–Valentine leukocidin gene.[26,27] The myriad clinical manifestations of MRSA and methicillin-sensitive S. aureus (MSSA) include furunculosis, folliculitis, impetigo and cellulitis, the last of which will not be discussed in this article.

Athletes, from professionals to weekend warriors, have developed furunculosis in epidemic proportions. Many different types of sports participation may result in cutaneous S. aureus infection, including basketball, cross-country, fencing, football, rugby, soccer, volleyball, weight lifting and wrestling.[1,25] Skin-to-skin contact probably plays a primary role in basketball, football, rugby, soccer and wrestling; while contact with fomites may play a relatively larger role in sports such as cross-country, fencing, volleyball and weight lifting.[1,25] In practice, a combination of these factors causes epidemics of S. aureus.

The seminal paper of MRSA in athletes described a major epidemic in a US professional American football team, the St Louis Rams, in 2003.[28] A total of 9% of the team experienced furunculosis and lost 17 days of practice and competition. After a rigorous review of the epidemic, the investigators identified several risk factors in the development of furunculosis among athletes. First, the presence of turf burns increased the risk of infection. Players developed these turf burns quite often, at the rate of two- to three-times per week. Second, team mates shared towels regularly. An average of three players used a single towel. Third, before using the communal whirlpool, athletes did not shower. Fourth, athletic trainers did not have immediate access to hand sanitation between caring for athletes. Fifth, staff did not periodically clean the weights in the training room.

Several collegiate football epidemics have occurred as well.[29,30] Ten members of a 100-person college football team developed MRSA infections.[29] The presence of turf burns correlated with increased prevalence of MRSA infections (relative risk: 7.2). The relative risk of developing MRSA infection was also related to player position. The cornerback and wide receiver positions possessed relative risk values of 17.5 and 11.7, respectively. Body shaving, which represents a common practice among athletes, increased the risk of developing MRSA infection (relative risk: 6.1). Interestingly, the use of the whirlpool two-times or more per week increased the relative risk of developing MRSA infection to 12.2.

Furunculosis

Like other clinical manifestations of S. aureus infections, furunculosis occurs in athletes. Clinically, furunculosis manifests as tender, erythematous nodules, most commonly on exposed skin. Frequently, the diagnosis of furunculosis presents few challenges; very early lesions, however, may appear as acne or insect bite reactions.[1,25,31] Clinicians frequently confuse mature lesions of furunculosis with ruptured epidermoid cysts. All athletes with furunculosis should undergo incision and drainage.[1,25,31,32] As the prevalence of MRSA in athletes greatly exceeds that in the nonathletic population, clinicians should culture the material removed from the drainage. One study documented the increased risk of recurrence (relative risk: 33) of furunculosis in individuals who did not have cultures compared with those who did.[33] Sports medicine clinicians, armed with appropriate culture and sensitivity results, will appropriately treat infected athletes.

In general, the treatment of infected athletes requires a dual-pronged approach with both topical and oral antibiotics. Topical mupirocin twice-daily, in addition to oral dicloxacillin or cephalexin, clears MSSA furunculosis.[1,25,32] Most athletes who have furunculosis from MRSA will respond to topical mupirocin. Most MRSA-related furunculosis clears with oral doxycycline, minocycline or trimethoprim-sulfamethoxazole.[1,25,31,32] In addition, all athletes with furunculosis should apply warm compresses for 10 min, three-times daily to their affected areas. To minimize epidemics of furunculosis, athletes should use the same techniques described in the section on prevention of tinea corporis gladiatorum. In addition, athletes should not share helmets.

Clinicians should culture the nares of athletes with recurrent furunculosis or athletes on teams with epidemics. The presence of MSSA nasal colonization in athletes approaches 40%.[28,29] While the nasal colonization of MRSA is 1.3% in nonathletes, athletes and day-care contacts of MRSA-colonized individuals have a higher prevalence of MRSA (3%).[34] Other sites of S. aureus colonization include the axilla, crural and perianal areas. No studies have documented a decrease in epidemics with clearance of MRSA or MSSA colonization; however, athletes with documented carriage should use mupirocin twice-daily for 7 days in both nares with repeat dosing 4–6 months thereafter. Athletes can also decolonize their entire body with antiseptic agents (such as chlorhexidine gluconate) in conjunction with mupirocin. Assuming that mupirocin application decreases colonization and hence aborts potential epidemics, clinicians should recognize that many athletes (33% in one study) fail to apply the medication.[33]

Folliculitis

Unlike furunculosis, investigators have not studied the epidemiology of folliculitis in athletes. Staphylococcus folliculitis represents the most common infectious variant of folliculitis. Athletes, with intense skin-to-skin contact and those athletes who wear equipment or tight garments, such as female volleyball players, primarily develop these lesions.[1,25,32] Clinically, lesions develop on exposed skin or beneath equipment and appear as follicular pustules. Culture and sensitivity identifies the variant of S. aureus so that the clinician may prescribe specific therapy. The differential diagnosis of Staphylococcus folliculitis includes other infections such as Gram-negative folliculitis, Pseudomonas folliculitis and Pityrosporum folliculitis, and noninfectious folliculitis such as steroid folliculitis and acne. Lesions of molluscum contagiosum may also appear like folliculitis. Especially in athletes, clinicians should carefully examine for the presence of the characteristic white color and umbilication to exclude molluscum contagiosum. If doubt remains, as is the case occasionally with very small lesions, biopsy confirms the diagnosis of either folliculitis or molluscum contagiosum.

In general, the treatment of infected athletes requires a dual-pronged approach with both topical and oral antibiotics. Topical mupirocin twice-daily in addition to oral dicloxacillin or cephalexin clears MSSA folliculitis.[1,25,32] Most athletes who have MRSA folliculitis will respond to topical mupirocin. Most MRSA-related folliculitis clears with oral doxycycline, minocycline or trimethoprim–sulfamethoxazole.[1,25,31,32]

To prevent folliculitis, athletes should employ the same techniques used to minimize the effect of tinea corporis gladiatorum in athletes.[1]

Impetigo

Impetigo, another S. aureus cutaneous infection (also in some cases caused by Streptococcus species), occurs in athletes who experience intense skin-to-skin contact or who wear equipment.[1,25,32] The prevalence of sports-related impetigo has not been studied. Clinically, lesions develop on exposed skin or beneath equipment, and classically appear as honey-colored crusted erythematous plaques (Figure 7). The differential diagnosis of these early lesions includes other infections such as herpes gladiatorum and tinea corporis gladiatorum, and inflammatory conditions such as dermatitis, acne and early lupus erythematosus.[1,25,32] Clinicians must differentiate very early lesions, which tend to appear as nonspecific erythematous papules. Culture and sensitivity identifies the type of S. aureus so that the clinician may prescribe precise therapy.

Figure 7.

Impetigo.

In general, the treatment of infected athletes requires a dual-pronged approach with both topical and oral antibiotics. Topical mupirocin twice daily in addition to oral dicloxacillin or cephalexin clears impetigo caused by MSSA.[1,25,32] Most athletes who have MRSA will also respond to topical mupirocin. If oral antibiotics are required, most MRSA-related impetigo clears with oral doxycycline, minocycline or trimethoprim–sulfamethoxazole.[1,25,31,32]

Athletes and teams, at risk for developing impetigo, should employ the same techniques used to prevent tinea corporis gladiatorum outbreaks.[1]

Pitted Keratolysis

Athletes can also develop a bacterial infection of the foot, termed pitted keratolysis, that sports clinicians often misdiagnose. In one study, 14% of competitive athletes had pitted keratolysis.[35] Runners, along with basketball and tennis players, seem particularly susceptible.[1] Caused by various Gram-positive organisms such as Corynebacteria or Micrococcus species, pitted keratolysis may develop on the soles of any athlete.[1,32] Occlusive footwear coupled with sweating promote the growth of the organism. Athletes with this infection demonstrate discrete, small, crater-like pits on the soles and lateral and medial aspects of the toes; a foul-odor occurs frequently (Figure 8). Clinicians often misdiagnose pitted keratolysis as tinea pedis. The presence of the distinctive crater-like pits, a negative potassium hydroxide examination, and the lack of response to topical and oral antifungal agents characterize pitted keratolysis.

Figure 8.

Pitted keratolysis.

The therapeutic approach to pitted keratolysis focuses on the elimination of the Gram-positive organisms. Effective topical antibiotics include clindamycin and erythromycin.[1,32] Topical benzoyl peroxide not only kills the microorganisms, but also makes the skin dry and inhospitable for bacteria. No athlete should wear cotton socks; these promote the growth of Corynebacteria or Micrococcus species by keeping the microenvironment of the foot warm and moist. Synthetic socks, however, wick away the moisture and keep the feet dry and cool.[1,32] Recently developed material derived from coconut husks appears superior to their synthetic predecessors.

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