It's not a spider bite, it's community-acquired methicillin-resistant Staphylococcus aureus.

Skin and soft tissue infections caused by hospitalacquired methicillin-resistant Staphylococcus aureus, or HA-MRSA, have been a problem in hospital and nursing home settings for several years. In recent years, infections caused by a new isolate termed community-acquired MRSA (CA-MRSA) have been increasing in incidence, and outbreaks of CA-MRSA have been identified in other settings, including athletic teams and prisons. Community-acquired MRSA differs from HA-MRSA in that CA-MRSA is not multidrug-resistant and can usually be treated with clindamycin, trimethoprim/ sulfamethoxazole, or linezolid. Both organisms carry the staphylococcal cassette chromosomemecA (SCCmecA) gene that encodes resistance to the -lactams—the class of antibiotics most commonly used in treating skin and soft tissue infections. At this time, it is not known whether CAMRSA is the result of HA-MRSA that escaped the hospital setting and mutated to its present form or is community-generated in origin. Several studies are currently being conducted in molecular genetics to identify the source of CA-MRSA and effectively treat it. This article presents a case review of several CA-MRSA infections identified in a community clinic setting, identifies clues that might lead the clinician to suspect a CA-MRSA infection, recommends questions to consider in making this diagnosis, and discusses options for treatment. It may be that contact with prisons or prisoners needs to be placed on the list of known risk factors associated with CA-MRSA. Case Review From July 2002 to September 2003, 10 patients were identified as having CA-MRSA skin and soft tissue infections at an indigent health care clinic in San Antonio, Texas. These infections were classified as community-acquired MRSA based on several factors: (1) none of the patients had risk factors for nosocomially acquired MRSA (ie, recent hospitalization or surgery) or those risk factors previously associated with acquisition of MRSA outside a short-term care setting: residence in a long-term care facility, current intravenous drug abuse, or underlying illnesses such as cardiovascular or pulmonary disease, diabetes mellitus, malignancy, or chronic skin disease such as eczema, and (2) antimicrobial resistance patterns were consistent with CA-MRSA—ie, they showed susceptibility to several classes of antimicrobial agents other than -lactams. Patients were identified through a positive wound culture using an aerobic/anaerobic Culturette. Many had been diagnosed and treated for other causes of their infection, including spider bites, impetigo, and varicella zoster. Four of the patients had been incarcerated and reported they had been treated for recurring skin infections several times while in prison. One of these 4 patients had a positive nasal culture for CA-MRSA. The other 6 patients had contact with either a prison facility or someone recently released from prison. One patient also played on his high school football team. Several patients were treated by other providers for what were thought to be spider bites. All CA-MRSA infections treated at the community clinic responded well to clindamycin, mupirocin, and drainage of the abscess, if present. The sensitivity pattern was similar in the positive MRSA cultures in that all were sensitive to clindamycin, rifampin, trimethoprim/sulfamethoxazole, and vancomycin (Table 1). All the isolates were resistant to amoxicillin/clavulanic acid, cefazolin, erythromySubmitted, revised, 20 October 2003. From the Bishop Ernest T. Dixon Clinic, Methodist Healthcare Ministries of South Texas, Inc., San Antonio. Address correspondence to Tamara J. Dominguez, MD, Bishop Ernest T. Dixon Jr. Clinic, 1954 East Houston Street #201, San Antonio, TX 78202. This work was supported by Methodist Healthcare Ministries of South Texas, Inc., which operates the Dixon Clinic.