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Issue: April 2006
April 01, 2006
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CA-MRSA becoming fact of life for some athletes involved in contact sports

Sharing towels, bars of soap and other personal items, including equipment, increasingly appears to be a transmission factor, researchers say.

Issue: April 2006

NAPA, Calif. — The fall of 2003 was not merely a “breakout� season for the football team at the University of Southern California, “but an outbreak season,� said Irving Steinberg, PharmD, at the Fifth Pediatric Infectious Diseases Society Conference.

And that outbreak of skin and soft tissue infections is indicative of what is happening across the country. Cases of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) have been occurring in sports teams, particularly among football players and wrestlers, according to Steinberg, who is director of the division of pediatric pharmacotherapy, department of pediatrics at Los Angeles County and USC Medical Center.

In August 2002, two USC players were hospitalized for skin and soft tissue infections that failed therapy with cephalexin and levofloxacin (Levaquin, Ortho-McNeill) due to MRSA. During training camp a year later, four more players were hospitalized for skin and soft tissue infections due to MRSA. Ten cases occurred during 2003 camp. Most of the cases were boils, but folliculitis and insect bites were also among presenting signs. Doxycycline and rifampin were used in the players who were not hospitalized, according to Steinberg, who is also associate professor of pediatrics and clinical pharmacy at the USC Keck School of Medicine and School of Pharmacy.

Infection control measures were instituted that called for hexachlorophene showers, but two more cases occurred. Twenty-six players carried the organism in their nares and eight of the 26 were methicillin resistant. A study in Emerging Infectious Diseases showed that locker room proximity to the index case was a factor in those who became infected or a carrier.

“In the epidemiologic data, nasal carriers were 60 times more likely to have a locker adjacent to or across from the skin and soft tissue infection case and 47 times more likely to share towels with their teammates. Carriers were also more likely to live on a campus dorm or the frat house and have a greater number of roommates as compared with those who live off campus,� Steinberg said.

Sharing bars of soap after infection control practices that were already implemented was also implicated in infection. “So, even in the best of attempts, oftentimes it takes more than one pass at trying to encourage proper hygiene. And so this brings together the precipitating factors in one fell swoop: crowding conditions where the players are sequestered during training camp, turf burns and abrasions, sharing and frequent contact, although it’s interesting that none of the opposing teams that were in contact with the USC football team came down with infection themselves. I guess what you can't tackle, you can’t get infected by,� Steinberg said.

Guidelines

The CDC and state health departments have implemented some guidelines that any physician can recommend to schools and coaches. Make sure all wounds are covered. Encourage good hygiene, including using soap dispensers instead of bars in the locker room showers. Discourage the sharing of towels and other equipment including playing equipment. Establish routine cleaning schedules for the equipment. Make sure athletes report skin lesions.

“One of the problems occurring in multiple locker rooms across the country is making sure that in fact the routine abrasion is taken care of rather than letting it fester,� Steinberg said.

Although sports figures may make the news when they have MRSA infections, the problem gained national recognition in pediatrics, he added, with four deaths in Minnesota and North Dakota in 1999 from CA-MRSA.

“We’ve all had cases of patients with severe sepsis,� he said, adding that treating patients quickly and correctly is vital. “Therapeutic modalities have to be maximized immediately.�

MRSA definitions that separate community associated with hospital acquired are blurring, he added. “The more that MRSA cycles out from the hospital back into the community, the more you see a blurring of these antibiotic susceptibility patterns, as regional variation suggests,� he said.

D tests should be done on all erythromycin-resistant, clindamycin-sensitive strains as inducible resistance may impair clindamycin’s in-vivo activity, he said, and it is important to know the susceptibilities in the community where one practices. Chloramphenicol and clindamycin tend to have activity against CA-MRSA. The activity of erythromycin and fluoroquinolones against CA-MRSA vary; they are more resistant in some communities than others. CA-MRSA is usually about 98% susceptible to trimethoprim-sulfamethoxazole (TMP-SMX).

Health-associated MRSA (HA-MRSA) is frequently resistant to clindamycin, chloramphenicol and erythromycin. It is usually susceptible to TMP-SMX. Daptomycin tends to be the most bactericidal, but pediatric experience is limited. Linezolid is bacteriostatic, but has been successful in comparative trials of skin and soft tissue infections and some invasive disease, according to Steinberg.

Vancomycin is advocated in pneumonia and sepsis cases, but Steinberg said he strongly considers combination therapy with aminoglycoside or clindamycin. For serious infections, some experts are advocating higher trough concentrations and others are calling for continuous infusion of vancomycin to get a stable, higher therapeutic level. Low serum levels and genetic characteristics of invasive HA-MRSA, such as accessory gene regulator polymorphisms, are linked to vancomycin insensitivity and clinical/microbiologic failure.

“The real purpose of having a dosage relationship to efficacy is that you can maximize both the pharmacokinetics and pharmacodynamics. Since children clear vancomycin faster, our challenge is not giving them low enough doses to be less toxic, but giving them high enough doses to provide efficacy and avoid the exposure or the uncovering of resistance,� he said.

Risks and trends

People who are at increased risk for CA-MRSA infections are Alaska natives, Pacific Islanders, Native Americans and blacks, as well as travelers to the Middle East and their families, correctional facility inmates, athletes in contact sports, military personnel and the homeless, along with those who have previously used antibiotics, according to Steinberg.

Activities that increase the risk of acquiring MRSA are cosmetic body shaving and spa or whirlpool use, depending on the frequency of use and the number of participants. Data from Alaska suggest that “fomites certainly can survive very long periods within a spa,� he said.

MRSA cases are increasing in children and adults, he said. “In children, it was a more profound jump. From 2001 to 2002, the total number of staph cultures that were attributable to wounds was 45%, only 4% being from MRSA. Jump to 2003 to 2004 and MRSA is up to 28%, nearly the adult value, again with about half of the staph infections being of a wound,� he said.

Again, there is geographic variability. Texas has more CA-MRSA, but it tends to predominantly be skin and soft tissue infections, he said, but underlying risk factors (recent MRSA infection/colonization, chronic disease, recent hospitalization/surgery, long-term institutional care, indwelling catheter, day care center attendance, IV drug abuse, antibiotic use in the prior six months, household contact with a risk factor) may increase the likelihood of invasive disease.

A connection between cystic fibrosis and MRSA has not been well established, but the Washington University Pediatric Cystic Fibrosis Center looked at 45 of 227 evaluated patients with MRSA. They found that 16% were positive for the Panton-Valentine leukocidin (PVL) strain through genetic typing. PVL-positive strains are implicated more often in pneumonia, empyema and necrotizing pneumonia, he said.

“The PVL-positive patients were more likely to be admitted for IV antibiotics, had a higher rate of focal infiltrates plus or minus cavitation, beyond what the usual pulmonary work-up contains. They also have a larger decrease in FEV1 than the preceding year’s maximum FEV1 and they tended to have higher white cell counts, higher absolute neutrophil counts, as well as fever,� he explained. “So, those patients with a PVL-positive toxin mediation are going to be somewhat sicker than the customary findings within the cystic fibrosis population.�

Lee et al published a study of 69 children with skin and soft tissue abscesses due to MRSA — 65% of the patients were black, 34% in day care, 21% with family members who were health care workers, 29% had been hospitalized recently, 12% had had a prior skin abscess and 90% underwent an incision and drainage. Severe tenderness was seen in about 60% of the patients, fever in about 40%.

Only 7% of the patients were given an initial antibiotic that was active against their isolate. However, even infections that were initially treated with an ineffective antibiotic recovered. So, it could be that incision and drainage were more important than the antibiotic in treating superficial skin abscesses, even if MRSA is present.

The predictor of hospitalization was a lesion that was initially greater than 5 cm. Steinberg said this was a guide point for clinicians. A larger lesion may be a reason to give more pathogen-specific antibiotics, he said.

“A lot of the outcomes with superficial skin abscesses are going to be based on the local management, not necessarily the antibiotic management. By the time you get the cultures back with the susceptibilities, you may already have a patient who has done well on whatever they've been on,� he said.

All skin and soft tissue infections are not created equal; each must be assessed and followed diligently by the clinician. In minor infections, patients are likely to get well with proper, local management regardless of whether the antibiotic matches the organism susceptibility, but complications must be anticipated, and doctors must monitor these patients closely.

“Knowing about their health care risk factors, knowing about any kind of chronic underlying problems can help us in sorting out patients who should be given pathogen-specific therapy,� Steinberg said.

This article first appeared in Orthopedics Today’s sister publication, Infectious Disease News.

For more information:

  • Steinberg I. MRSA therapeutics: dilemmas of preference and amount. Presented at the Fifth Pediatric Infectious Disease Society Conference. Oct. 9-11, 2005. Napa, Calif.
  • American Thoracic Society. Guidelines for the management of adults with hospital-acquired, ventilator-associated, and healthcare-associated pneumonia. Am J Respir Crit Care Med. 2005;171:388-416.
  • Blot S. MRSA pneumonia: better outcome through continuous infusion of vancomycin? Crit Care Med. 2005;33:2127-2128.
  • Braun L, Craft D, Williams R, et al. Increasing clindamycin resistance among methicillin-resistant Staphylococcus aureus in 57 northeast United States military treatment facilities. Pediatr Infect Dis J. 2005;24:622-626.
  • Craig WA, Andes D, LaPlante KL, et al. In vivo activity of clindamycin (CLIN), daptomycin (DAP), doxycycline (DOXY), and linezolid (LND) against clindamycin inducible-resistance (CIR) community-associated Methicillin-resistant Staphylococcus aureus (CA-MRSA) in a murine thigh-infection model. Abstract #A-428. Presented at the 45th Annual ICAAC. Dec. 16-19, 2005. Washington.
  • Fridkin SK. Active Bacterial Core Surveillance Program of the Emerging Infections Program Network. Methicillin-resistant Staphylococcus aureus disease in three communities. N Engl J Med. 2005;352:1436-1444.
  • Kaplan SL, Hulten KG, Gonzalez BE, et al. Three-year surveillance of community-acquired Staphylococcus aureus infections in children. Clin Infect Dis. 2005;40:1785-1791.
  • Micek ST, Dunne M, Kollef MH. Pleuropulmonary complications of Panton-Valentine leukocidin-positive community-acquired methicillin-resistant Staphylococcus aureus: importance of treatment with antimicrobials inhibiting exotoxin production. Chest. 2005;128:2732-2738.
  • Nguyen DM, Mascola L, Brancoft E. Recurring methicillin-resistant Staphylococcus aureus infections in a football team. Emerg Infect Dis. 2005;11:526-532.
  • Purcell K, Fergie J. Epidemic of community-acquired methicillin-resistant Staphylococcus aureus infections: a 14-year study at Driscoll Children’s Hospital. Arch Pediatr Adolesc Med. 2005;159:980-985.
  • Tenover FC. New approaches to the molecular epidemiology of community-associated MRSA. Abstract #1323.Presented at the 45th Annual Interscience Conference of Antimicrobial Agents and Chemotherapy. Dec. 16-19, 2005. Washington.
  • Rello J, Sole-Violan J, Sa-Borges M, et al. Pneumonia caused by oxacillin-resistant Staphylococcus aureus treated with glycopeptides. Crit Care Med. 2005;33:1983-1987.
  • Baggett HC, Hennessy TW, Rudolph K, et al. Community-onset methicillin-resistant Staphylococcus aureus associated with antibiotic use and the cytotoxin Panton-Valentine leukocidin during a furunculosis outbreak in rural Alaska. J Infect Dis. 2004;189:1565-1573.
  • Lee MC, Rios AM, Aten MF, et al. Management and outcome of children with skin and soft tissue abscesses caused by community-acquired methicillin-resistant Staphylococcus aureus. Pediatr Infect Dis J. 2004;23:123-127.