The incidence of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) infection in high school and college athletes remains high, and those practicing contact sports lead the pack, according to a new study.

Though football and wrestling pose the greatest relative risks for contracting these drug-resistant infections, Dr. Tim Braun reported, "CA-MRSA infections are much more than simply a wrestling and football problem. For any athlete presenting with a potential bacterial skin lesion, the differential diagnosis must include CA-MRSA."

The study, online in Medicine & Science in Sports & Exercise, also found substantial variations in treatment and management protocols. For example, although the primary recommended treatment is incision and drainage, only about 20% to 30% of CA-MRSA lesions were treated with this procedure.

The study has two relatively novel aspects, said Dr. Brau. First, it's one of few studies that have quantified the incidence of CA-MRSA within athletics prospectively; most quantitative studies have been retrospective and among less-specific populations.

Second, he said, the wide variability in treatment that was found indicates the need for collaboration between professions "to ensure proper and prompt treatment and follow-up" of CA-MRSA cases. "Our results may provide the largest snapshot to date of the CA-MRSA infection impact in high school and intercollegiate athletics," the authors write.

The two-part study consisted of two surveys sent to high school and intercollegiate athletic programs in the United States. In the 2015-16 survey, 269 athletic trainers completed a one-time retrospective questionnaire, while for the 2016-17 survey, 217 trainers reported data bimonthly during the academic year.

Of the 310 sport-specified, physician-confirmed CA-MRSA cases in the 2015-16 survey, most occurred in football (40%), followed by wrestling (32%), male basketball (5%), male soccer (4%), female soccer (4%), baseball (3%) and female basketball, female volleyball, softball, male lacrosse and "other" sports (all 2%).

There were 332 physician-confirmed CA-MRSA infections, 42% of which underwent susceptibility testing; 72% underwent culture testing and 29% incision and drainage procedures. Isolation from teammates was undertaken in only 12.7% of cases; areas frequented by student-athletes were decontaminating in about 38% of cases.

In the 2016-17 survey, 23.5% of respondents reported at least one physician-confirmed CA-MRSA infection over the reporting year, with a total of 187 CA-MRSA infections, for an annual incidence of 20.3 per 10,000 student-athletes.

CA-MRSA infection

CA-MRSA infections were reported in 19 sports, but the majority (58%) occurred in football, followed by wrestling (12%), male soccer (4%) and female soccer (4%). Male gymnastics (410.9 per 10,000) and male rugby (232.6 per 10,000), however, reported the highest incidence rates.

Ninety-one percent of multiple-infection cases occurred among team members or student athletes using the same athletic facilities, such as locker rooms, playing surfaces, weight rooms, showers, and whirlpools.

Over the 2016-17 academic year, 18% of 1,027 suspicious bacterial skin lesions were confirmed CA-MRSA infections. Of those student-athletes, 27% underwent susceptibility testing, 40% culture testing and 21% incision and drainage.

In the 90 instances in which a specific antibiotic was reported as given for suspicious bacterial lesions, the most-issued oral antibiotic (24.9%) was Trimethoprim-sulfamethoxazole.

Athletes remain a high-risk population for CA-MRSA, Dr. Braun said. "We are only beginning to identify the extent and impact of CA-MRSA infections on athletes."

Rather than simply undertaking empiric antibiotic treatment, Dr. Braun advised, physicians should bear in mind that "mild purulent skin infection abscesses without signs of systemic infection often respond to incision and drainage. By solely prescribing empiric antibiotics, physicians are contributing to the development of newer strains with heightened resistance patterns."

He largely agrees with the report's advice favoring incision and drainage over empirical antibiotics, provided a lesion is smaller than about 3 cm to 5 cm. Still, noted, some antibiotics, such as clindamycin, have been shown to be associated with lower rates of MRSA recurrence. Finally, though both are important, he said, "Personal hygiene matters more than environmental hygiene," in preventing CA-MRSA.