Ask the Expert: Skin/Soft Tissue Infection in a Patient With HIV
A 49 year-old inmate presents on sick call with concerns about a pimple on her sacral area that has been problematic for three weeks. She has been incarcerated for one year. She has untreated asymptomatic HIV infection with a recent CD4 count of 233 and a HIV-1 viral load of 174,000 copies/mL. She says that "she popped it (the pimple)," and though it appeared to improve initially, "it came back again". She also has two similar areas on her left hand and left inner thigh. She denies fevers, chills, nausea/vomiting, headache, myalgias/arthralgias, fatigue, cough/dyspnea. She has been feeling depressed recently and has not been bathing regularly. She has a history of cocaine dependence but denies injection drug use. She takes acyclovir regularly for genital HSV suppression but is on no other medications.
Physical exam is notable for BP 120/67, pulse 75, respirations 14, temperature 37.5° C, and weight 130 lbs. She appears disheveled and has poor dentition. She has a supple neck with full range of motion and no palpable lymphadenopathy. Her chest is clear to auscultation, and her cardiac exam reveals a regular rate and rhythm, normal S1 and S2, and no cardiac murmurs, rubs, or gallops. Her abdomen is soft, nontender with normoactive bowel sounds and no hepatosplenomegaly. Her extremities show no cyanosis, clubbing or edema. Skin examination is notable for two small 2.5 cm abscesses on the dorsum of her left hand and two similar areas on the left inner thigh. She has a 6 x 8 cm sacral abscess, with erythema surrounding induration and some oozing of thick yellow fluid. There are no vesicular lesions. Her neurological exam is nonfocal.
QuestionsQuestion: What tests should you perform/order, if any?
Answer: A bacterial culture of the oozing fluid from the sacral abscess would be helpful since this is a new visit for this inmate with a new skin/soft tissue infection. This infection could be due to a variety of organisms, including community-acquired methicillin-resistant Staphylococcus aureus (MRSA). The susceptibility pattern for this organism had not been well established at the facility where she is incarcerated. If the patient appeared systemically ill with fever, chills, chest pain, cough, dyspnea, abdominal pain, nausea, vomiting, or weight loss, then bacterial blood cultures, a complete blood count, and a chest x-ray should also be obtained. One could also consider performing a ppd if any question of tuberculosis is considered.
A culture is performed, and yields two colonies of coagulase positive Staphylococcus (S. aureus). The organism is methicillin-resistant by PBP2A latex test, which indicates resistance to penicillins, cephalosporins, beta lactam/beta lactamase inhibitor combinations, imipenem and other beta lactams. The organism is reported as sensitive to Clindamycin, Gentamicin, Levofloxacin, Trimeth_sulfamethoxazole, and Vancomycin.
Q: What treatment(s) should you offer this inmate?
A: There are two important treatments to consider: antibiotics and surgical debridement. In general, empiric oral antimicrobial therapy to cover common skin/soft tissue organisms, such as Streptococcus and Staphylococcus, including MRSA, should be given pending final culture results or based on a known antibiogram within the institution, indicating known resistance patterns for MRSA. Antibiotics are not always needed if the infection is localized and good wound care is available. In this patient with advanced HIV disease, multiple abscesses, and a history of not adequately caring for herself, it is prudent to offer oral antimicrobial therapy. Once the isolate's final susceptibility pattern is known, therapy can be tailored. Unlike hospital-acquired MRSA strains, which are usually resistant to multiple antibiotics, community-acquired (CA) MRSA strains are often resistant only to beta-lactam antibiotics. Thus, the empiric regimen might include agents such as trimethoprim/sulfamethoxazole, doxycycline, or clindamycin, with or without rifampin. Rifampin monotherapy is NOT recommended, as resistance to this agent can evolve rapidly. Ideally, empiric therapy should be based on institutional resistance patterns for MRSA, if known. In the setting of an MRSA outbreak within a facility, all cases do not require a culture, if the outbreak is well defined with a known established susceptibility pattern for the etiologic isolate. The addition of rifampin for improved clinical response is often reserved for patients with recurrent infections or serious infections in which bone, blood, hardware, and/or deep tissue (i.e., fasciitis) is involved. Surgical debridement is usually reserved for deep infections and/or infections with associated fluctuance that are not draining adequately. Although this inmate had a fairly large sacral abscess, it was open and draining well without areas of fluctuance or devitalized tissue. Therefore, no surgical debridement was required. Depending on the sophistication of the facility, this patient could be managed with outpatient care with wound dressing changes and monitoring of medication in the prison/jail clinic at regular intervals, as opposed to referral to an outpatient care clinic at a local hospital or to an infectious disease clinic in the community. Whether or not the inmate took her medications on pill line as opposed to "keeping on person" is an individual decision that should be made by the provider, keeping the extent of disease, the compliance of the inmate, and the level of understanding of the problem by the inmate in mind. One last point is that this inmate should be re-examined after the lesions have cleared to be sure a cyst (e.g., pilonidal) was not missed and predisposed her to this infection.
Q: What infection-control measures, if any, should you recommend?
A: Personal hygiene and environmental sanitation practices are critical. Wound dressings must be performed with strict attention to contact precautions. Frequent hand washing, daily bathing, and proper towel hygiene should be emphasized as discussed in detail in the spotlight on MRSA article in this issue of HEPP Report. If inmates and staff understand how CA-MRSA is transmitted, then infection control efforts are more likely to be successful.
The inmate was treated empirically with trimethoprim/sulfamethoxazole (160-800) bid for 14 days with daily wound packing with sterile gauze and wet to dry dressing changes. The areas dried up completely within a period of 3 weeks, and she suffered no complications.
CA-MRSA outbreaks continue to increase. Recent evidence suggests that this organism contains the Panton Valentine leukocidin gene, which codes for the production of cytotoxins that cause tissue necrosis and leukocyte destruction leading to skin and soft tissue infections or necrotizing pneumonia. Because no systematic, population-based surveillance of CA-MRSA isolates exists, the true prevalence is not known. Based on previous experience with penicillin-resistant strains, experts estimate that up to 25% of CA-SA may be MRSA within the next five to 10 years. Patients with CA-MRSA infections are at risk for life-threatening infections, particularly if a beta-lactam antibiotic is used and the infecting strain proves to be resistant. Judicious use of antibiotics, including consideration of institutional or individual resistance patterns in choosing the appropriate treatment, is very important in managing CA-MRSA infections. Use of agents such as linezolid and vancomycin should be reserved for more serious infections, such as bacteremia, endocarditis, and acute osteomyelitis.
Bethany Weaver, D.O., M.P.H., is Acting Instructor of Medicine at University of Washington Center for AIDS & STD Research (CFAR) and Northwest Correctional Medicine Education Program. Disclosures: Pfizer stockholder.
This article was provided by Brown Medical School. It is a part of the publication HEPP Report.