CA-MRSA. The New Sports Pathogen

Transcription

1 _ON2605-Kurkowski.qxd 9/13/07 2:25 PM Page 310 CA-MRSA The New Sports Pathogen Christina Kurkowski Skin infections in athletes caused by community-associated (CA-MRSA) have been observed within many cities throughout the United States and within many countries throughout the world (Centers for Disease Control and Prevention [CDC], 2003). As the incidence rises in the athletic population, clinicians must learn to identify risk factors for CA-MRSA, diagnosis and treat infections with judicious use of antimicrobial agents and facilitate strategies to limit transmission. Recently, a new consensus guideline for handling CA-MRSA outbreaks in sports has been released by the CDC (Gorwitz et al., 2006). This article includes a review of the evolution of MRSA; distinguishes between healthcare associated (HA-MRSA) and CA-MRSA; and reviews the diagnosis, management, and prevention strategies to limit transmission of CA-MRSA. Skin infections in athletes caused by communityassociated Methicillin-resistant Staphylococcus aureus (CA-MRSA) have been observed within many cities throughout the United States and within many countries throughout the world (Centers for Disease Control and Prevention [CDC], 2003). As the incidence rises in the athletic population, clinicians must learn to identify risk factors for CA-MRSA, diagnose and treat infections with judicious use of antimicrobial agents, and facilitate strategies to limit transmission. Recently, a new consensus guideline for handling CA- MRSA outbreaks in sports has been released by the CDC (Gorwitz et al., 2006). This article includes a review of the evolution of MRSA; distinguishes between healthcareassociated (HA-MRSA) and CA-MRSA; and reviews the diagnosis, management, and prevention strategies to limit transmission of CA-MRSA. A 14-year-old male wrestler presents to the clinic for follow-up of a sore swollen left knee that started 3 days ago. He was seen in the emergency department last night and was given the diagnosis of a patellar cellulitis and started on Cephalexin 500 mg three times daily. His medical history is unremarkable. He now complains of left groin pain that started today during school. He reported to the school nurse and was found to have a fever and a lump in his groin area and was urgently referred to his primary care provider for evaluation. He presents with a tender red patellar abscess with a painful erythematous nodule and cellulitis of the adjacent tissue. Evolution of Staphylococcus Aureus Alexander Fleming discovered penicillin in 1929, and penicillin was first used in humans in In 1941, the first case of penicillin-resistant Staphylococcus aureus (PRSA) was discovered. Methicillin was developed to treat PRSA and was first used in 1960, and in 1961 (MRSA) came into existence. MRSA is defined as an isolate of Staphylococcus aureus that shows resistance to any semisynthetic penicillin such as Methicillin. In the last 4 decades, MRSA has been one of the most widely known multidrug-resistant organisms in healthcare institutions. Data from the U.S. National Nosocomial Infections Surveillance System (NNIS, 2004) for 2004 showed that 61% of all Staphylococcus aureus isolates in intensive care units harbored Methicillin resistance. Since its initial identification in 1961, many risk factors for healthcare-associated Methicillin-resistant Staphylococcus aureus (HA-MRSA) infection have been recognized. These include prolonged hospitalizations, intensive care unit stays, use of invasive procedures and catheters, dialysis or other medical comorbidities, and frequent antibiotic exposure (Lowy, 1998). Over the past decade, however, community outbreaks of MRSA infections have been reported with increasing frequency in young persons without healthcare exposures or associated risk factors, such as athletes. The report of 4 pediatric fatalities from fulminant CA-MRSA infections in alerted the medical community to the virulence of these organisms (CDC, 1999). In most cases, CA-MRSA strains have shown a predilection to cause skin and soft tissue infections. As the incidence rises in the community setting, it is essential for orthopaedic healthcare providers to recognize and treat potential CA-MRSA infections appropriately. When MRSA infections initially emerged in the community, most strains were thought to represent organisms that had spread from healthcare institutions. CA-MRSA has a number of characteristics that help distinguish it from healthcare-associated MRSA, including Christina Kurkowski, MS, RN, ONC, ONC-P, CNOR, APNP, RNFA at Ministry Medical Group and Adult Nurse Practitioner at Thedacare Physicians Waupaca Family Medicine, Plover, WI. The author has no significant ties, financial or otherwise, to any company that might have an interest in the publication of this educational activity. 310 Orthopaedic Nursing September/October 2007 Volume 26 Number 5

2 _ON2605-Kurkowski.qxd 9/13/07 2:25 PM Page 311 a pulsed-field gel electrophoresis pattern; the production of specific toxins, including Panton-Valentine leukocidin (PVL) toxin, which encode a pore-forming toxin that evades the immune system, targeting leukocytes and erythrocytes, inducing an intense inflammatory cascade and ensuing enzymatic tissue necrosis; and then a resistance pattern. A few years ago, the CDC completed studies looking at over 1,200 different isolates of Staphylococcus. Deoxyribonucleic acid (DNA) cleavage testing with various enzymes was run in a gel, and then the pulsed electrophoresis patterns were sorted out. This process was similar to DNA fingerprinting for people, and it helped to sort out Staphylococcus aureus. Using an 80% similarity threshold, the CDC identified these isolates into eight patterns, and they called them USA Most HA-MRSA infections are typically associated with the pattern USA 100, whereas community-associated MRSA infections typically fall into the USA 300 pattern (Kowalski, Berbari, & Osmon, 2005). Associated Risk Factors for CA-MRSA Risk factors for acquisition of CA-MRSA remain understudied, though certain populations have demonstrated greater risk. Table 1 provides a comparison of risk factors between HA-MRSA and CA-MRSA strains. There are a number of associated factors for this infection, including limited time for hygiene. Persons in crowded conditions may be at higher risk, especially if personal hygiene is lacking. Outbreaks have been described in correctional facility inmates, military recruits (Sanford, Windmer, Bale, Jones, & Wenzel, 1994), men who have sex with men, and users of intravenous drugs (Kowalski et al., 2005). Competitive athletic participants at all levels have been particularly susceptible to skin and soft tissue infections caused by CA-MRSA, especially in football, wrestling, and rugby (CDC, 2003). Other associated factors are sharing personal items, skin cuts and abrasions from sports participants on Astroturf, and frequent skin-to-skin contact. All of these factors seem to predispose to the spread of this infection (see Table 2). EVALUATION OF THE ATHLETE This particular case study of a 14-year-old wrestler is complicated due to the general complaints of knee pain, groin pain, and fever. For this reason, a thorough evaluative history and inspection of the athlete is required to narrow down the variety of possibilities. The diagnosis of knee and groin pain in athletes is often difficult because the anatomy of the region is complex and there are often coexisting pathologies. This illustrates how easy it would be to overlook a more serious condition related to the groin by assuming it was a musculoskeletalrelated injury. A thorough history of the athlete identifying any possible risk factors for CA-MRSA, including other recent skin infections, trauma, hospitalization, close skin contact with other people, infection from drug use, diabetes mellitus, or chronic venous insufficiency. He is a wrestler and reported a skin abrasion at his last meet. A review of medications, supplements, and herbal preparations is TABLE 1. COMPARISON OF RISK FACTORS ASSOCIATED WITH HA-MRSA AND CA-MRSA INFECTIONS HA-MRSA Infections Older age: Elderly Prolonged hospitalization Intensive care unit admission Hemodialysis Indwelling lines and catheters Invasive procedures Comorbid medical conditions Institutionalization CA-MRSA Infections Younger age: Children, young adults Certain ethnic groups: Native American, Alaskan Natives, Pacific Islanders Persons in crowded living conditions Correctional facility inmates Users of intravenous drugs Men who have sex with men Athletes in contact sports Persons exposed to frequent antibiotic use Persons exposed to MRSA close contacts Note. Adapted from Borlaug, Davis, and Fox (2005). HA-MRSA = healthcare-associated ; CA-MRSA = community-associated Methicillin-resistant Staphylococcus aureus; MRSA = Methicillin-resistant Staphylococcus aureus. TABLE 2. TACTICS FOR PREVENTION OF CA-MRSA INFECTIONS IN ATHLETES Prevention of Outbreaks of CA-MRSA in Athletes Keep hands clean by washing thoroughly with soap and water or by using alcohol-based hand sanitizer routinely Encourage immediate showering following activity (soap dispensers) Avoid whirlpools and common tubs; adequately clean and dry the ones you have Properly wash towels (>70 C), wash gear (1 tb. bleach, 1 qt. water) Avoid sharing towels, razors, and daily athletic gear Encourage reporting of lesions Prevention/early treatment of abrasions Cover lesions with clean, dry bandages Wash soiled clothes/linens with hot water and detergent and machine dry Wear gloves when caring for wounds, clean and disinfect patient-care surfaces with EPA-registered hospital disinfectant after use (Cavicide) Clean weightlifting/workout equipment with detergent/ disinfectant Note. Adapted from Kowalski, T. J., Berbari, E. F., & Osmon, D. R. (2005). CA-MRSA = community-associated Methicillin-resistant Staphylococcus aureus; EPA = Environmental Protection Agency. Orthopaedic Nursing September/October 2007 Volume 26 Number 5 311

3 _ON2605-Kurkowski.qxd 9/13/07 2:25 PM Page 312 also necessary, as well as a general medical family history. Any complaint of inflammation of the skin and subcutaneous tissue, itchy rash (colliculitis), furuncles, pustules, or abscesses would be concerning and indicative of MRSA. It is also important to inquire about any localizing pain or symptoms distant from the lesion, which may suggest systemic spread. Additionally, it is necessary to gather a complete account of his symptoms, their duration, progression, severity, and how they affect activities of daily living. The actual physical examination would include inspection for any cellulitis, furuncles, abscesses, folliculitis, or impetigo, which are all indicative of MRSA (Martinez-Aguilar, Hammerman, Mason, & Kaplan, 2003). The main observable signs of osteomyelitis would be bone tenderness and possible swelling and redness. After completion of the physical examination, lab and diagnostic tests may need to be performed to rule out other possibilities and to confirm diagnosis of the pathology. These tests would include blood tests, blood cultures, and wound cultures. CASE STUDY CLINICAL EVALUATION RESULTS This athlete was found to have a superficial 2-cm circumscribed area of tender induration present on the patella with a surrounding 2- to 3-cm border of erythema. Fluctuance of the lesion was palpated. A red streak was visible on his thigh, and a tender 2-cm lymph node was palpable in the left groin. The patient was afebrile with normal vital signs and no other visible lesions. Clinical Manifestations CA-MRSA infections primarily manifest as skin and soft tissue infections, such as furuncles and carbuncles. The MRSA skin lesions typically present as one or more abscesses, with or without surrounding cellulitis; they are often erythematous, tender, and fluctuant (see Figure 1). Skin and soft tissue infections account for over 75% of infections caused by CA-MRSA (Naimi et al., 2003) and up to 90% of those described in the pediatric literature (Kaplan, 2005). Clinicians need to have a high suspicion FIGURE 1. Example of a CA-MRSA lesion. From Dominguez, T. J. (2004). It s not a spider bite, it s community-acquired methicillinresistant staphylococcus aureus. Journal of the American Board of Family Practice, 173, 224. Used with permission. for CA-MRSA in skin infections in athletes and should culture all pus, lance pustules, aspirate lesions, and order susceptibility testing on all Staphylococcus aureus isolates. Skin lesions may appear necrotic and can easily be misdiagnosed as a brown recluse spider bite. Impetigo and folliculitis occur less commonly, and rare cases of scalded skin syndrome have been caused by infection with strains harboring PVL toxins (Liassine et al., 2004). Management Treatment of cutaneous CA-MRSA infection requires drainage of the abscess (either spontaneously or after incision), considering and optimally confirming by culture the diagnosis of MRSA infection (Stevens et al., 2005), and treatment with systemic antimicrobial therapy to which the bacterial isolate is susceptible. For cases of mild illness in which the patient is afebrile, has an abscess <5 cm in diameter, and lacks other medical comorbidities incision and drainage with or without topical antibiotics may be a sufficient and definitive therapy (Lee et al., 2004). In a recent randomized, placebocontrolled trial in adult patients with deep skin abscesses and surrounding cellulitis, the majority of which were caused by MRSA, treatment success rates were over 90% for patients treated with incision and drainage alone (Gorwitz et al., 2006). Factors that may influence the clinical decision to supplement incision and drainage with antimicrobial therapy include the severity and rapidity of progression of the infection site or the presence of associated cellulitis. In one study (Lee et al., 2004), an infected site of >5 cm in diameter was associated with failure of incision and drainage without effective antimicrobial therapy. There is no ideal antibiotic for treatment of MRSA. From a clinical management standpoint, awareness of local resistance patterns for pathogens in the differential diagnosis of specific clinical syndromes is more important than formally categorizing possible MRSA infections as CA-MRSA or HA-MRSA. Unlike HA-MRSA isolates, which are usually resistant to multiple classes of antimicrobial agents, many CA-MRSA isolates to date have been resistant only to beta-lactams (the antimicrobial class that includes penicillins and cephalosporins) and macrolides/azalides (e.g., erythromycin, clarithromycin, azithromycin) (Fridkin et al., 2005). Most CA-MRSA isolates to date have been susceptible to trimethoprim-sulfamethoxazole, gentamicin, tetracycline, and clindamycin, although some Staphylococcus aureus isolates that appear erythromycin-resistant and clindamycin-susceptible by routine susceptibility testing exhibit in vitro resistance to clindamycin during therapy (inducible resistance) (Lewis & Jorgensen, 2005). TREATMENT OF CASE STUDY The wrestler in this study initially presented to the emergency department with a single abscess without cellulitis. At his initial visit, the surface of his nondraining infectious lesions was not incised or cultured for bacteria, and he received empiric treatment with an antibiotic to which his culture-positive MRSA strain was not susceptible. When he returned for follow-up 2 days later, his left knee abscess was still tender and fluctuant with 312 Orthopaedic Nursing September/October 2007 Volume 26 Number 5

4 _ON2605-Kurkowski.qxd 9/13/07 2:25 PM Page 313 cellulitis and lymphadenopathy of the ipsilateral groin. The lesion was incised and cultured, and the antibiotic was changed to 2 weeks of double-strength trimethoprim/ sulfamethoxazole twice daily, and all of his infectious skin lesion and swollen lymph node had completely resolved in that 2-week interval. Prevention of Transmission CA-MRSA is contagious and may affect not only the athletes but also their household contacts. Therefore, in addition to establishing the diagnosis of the infectious cutaneous lesion and appropriately treating the CA-MRSA skin infection, it is also important to prevent additional transmission of the causative bacteria. Healthcare providers should routinely ask about similar cases of skin infections in household members and other close contacts. If a potential outbreak of cases in a defined cohort outside of a single household (e.g., school, athletic team) is identified, the local public health department should be notified (Gorwitz et al., 2006). Orthopaedic healthcare providers need to know that if wounds cannot be adequately covered, exclusion of the athletes from participation should be considered (Borlaug, Davis, & Fox, 2005). It has been widely known that direct contact via the hands or gloves of healthcare workers is the major mode for transmission of HA-MRSA and other multidrugresistant organisms in healthcare institutions (Thompson, Cabezudo, & Wenzel, 1982). Possible risk factors for the acquisition and transmission of CA-MRSA infection in athletes include physical contact (enabling direct skinto-skin transmission of CA-MRSA), skin damage (resulting in nonintact epithelium that facilitates the entry of pathogens at that location), and sharing of equipment or clothing (providing a vehicle for bacterial transmission if they have not been cleaned or laundered between users). Clean equipment and other environmental surfaces with which multiple individuals have bare skin contact with a detergent/disinfectant that specifies Staphylococcus aureus on the product label and that is suitable for the type of surface being cleaned (Los Angeles County Department of Health Services, 2004). For nonporous surfaces (e.g., tile, stainless steel, epoxy, and linoleum) use an Environmental Protection Agency (EPA)-registered detergent disinfectant suitable for the type of surface being treated such as 3M Quat, Cavicide, or Johnson Virex II-256. If an EPA-registered product is not available, a 1:100 dilution ( ppm) of household chlorine bleach can be used for nonporous surfaces. For wood surfaces, scrub and disinfect with 1:10 dilution (5,000 6,150 ppm) of household chlorine bleach. Bleach solutions should be left on surfaces for at least 10 min to achieve maximum disinfection (Los Angeles County Department of Health Services, 2004). Summary Today, CA-MRSA is increasingly recognized as the agent responsible for skin infection outbreaks among sport teams, causing significant morbidity and lost days of practice. More data are needed to fully understand the epidemiology, microbiology, and pathophysiology of CA-MRSA infections and to identify optimal prevention and treatment strategies. From a clinical management standpoint, it is important to have a high suspicion for CA-MRSA in the otherwise healthy athlete. With the increasing prevalence of CA-MRSA, the empiric use of beta-lactam antimicrobials, such as cephalosporins or penicillins, without wound culturing is hazardous (Fleming, Brown, & Tice, 2006). Currently, the research supports incision, drainage with culture as a cornerstone of therapy, but awareness of local susceptibility patterns within one s community will assist in providing the best antimicrobial therapy when needed. Orthopaedic healthcare providers have an opportunity to educate athletes, coaches, and the public in the prevention of the transmission of this pathogen. REFERENCES Borlaug, G., Davis, J. P., & Fox, B. C. (2005). Community associated : Guidelines for clinical management and control of transmission. Retrieved June 3, 2006, from wisconsin.gov/communicable/pdf_files/camrsaguide_ 1105.pdf Centers for Disease Control and Prevention. (1999). 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5 _ON2605-Kurkowski.qxd 9/13/07 2:25 PM Page 314 Lewis, J. S., II, & Jorgensen, J. H. (2005). Inducible clindamycin resistance in Staphylococci: Should clinicians and microbiologists be concerned? Clinical Infectious Diseases, 40, Liassine, N. Auckenthaler, R., Descombes, M. C., Bes, M., Vandenesch, F., & Etienne, J. (2004). Communityacquired isolated in Switzerland contains the Panton-Valentine leukocidin or exfoliative toxin genes. Journal of Clinical Microbiology. 42: Los Angeles County Department of Health Services. (2004). Los Angeles County Department of Health Services guidelines for reducing the spread of Staph/CAMRSA in nonhealthcare settings. Retrieved June 12, 2006, from lapublichealth.org/acd/mrsa/mrsaguide.htm Lowy, F. D. (1998). Staphylococcus aureus infections. New England Journal Medicine, 339, Martinez-Aguilar, G., Hammerman, W., Mason, E. O., & Kaplan, S. L. (2003). Clindamycin treatment of invasive infections caused by community-acquired, Methicillinresistant and Methicillin-susceptible Staphylococcus aureus in children. The Pediatric Infectious Disease Journal, 22, Naimi, T. S., LeDell, K. H., Como-Sabetti, K, Borchardt, S. M., Boxrud, D. J., Etienne, J., et al. (2003). Comparison of community and healthcare-associated Methicillinresistant Staphylococcus aureus infection. Journal of the American Medical Association, 290, Sanford, M. D., Windmer, A. F., Bale, M. J., Jones, R. N. & Wenzel, R. P. (1994). Efficient detection and long-term persistence of the carriage of Methicillin-resistant Staphylococcus aureus. Clinical Infectious Diseases, 19, Stevens, D. L., Bisno, A. L., Chambers, H. F., Everett, E. D., Dellinger, P., Goldstein, E. J., et al. (2005). Practice guidelines for the diagnosis and management of skin and soft-tissue infections. Clinical Infectious Diseases, 41, Thompson, F. L., Cabezudo, I., & Wenzel, R. P. (1982). Epidemiology of nosocomial infections caused by. Annals of Internal Medicine, 97, U.S. National Nosocomial Infection Surveillance System. (2004). NNIS System Report, data summary from January 1992 through June American Journal of Infection Control, 32, Orthopaedic Nursing September/October 2007 Volume 26 Number 5