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PGY2 Infectious Diseases Pharmacotherapy Resident School of Pharmacy Temple University
Infectious Diseases Fellow Temple University Hospital
Associate Professor of Medicine Temple University School of Medicine/Temple University Hospital
Clinical Assistant Professor School of Pharmacy Temple University Department of Pharmacy Practice, 5th Floor 3307 North Broad Street Philadelphia, Pennsylvania 19140 fax 215/707-8326 jason.gallagher{at}temple.edu
Published Online, September 15, 2009. www.theannals.com, DOI 10.1345/aph.1M270
Case Report. A 21-year-old man with a history of intravenous drug abuse presented to the emergency department complaining of severe pain and swelling in the left thigh and fever of 1 week's duration after recent dynamic hip and screw surgery with hardware placement. Initial diagnostic tests included blood urea nitrogen (BUN) 10 mg/dL, serum creatinine (SCr) 1 mg/dL, and white blood cell (WBC) count 20.1 x 103/mm3 with 1.1% eosinophils. These values remained stable and the WBC count normalized by the time of discharge. Vancomycin was initiated after a bone scan showed likely osteomyelitis of the femur. Blood and hip joint cultures were negative. Due to the patient's improvement on vancomycin, oral linezolid 600 mg every 12 hours for a total of 8 weeks was prescribed.
Ten days after discharge, the patient returned to the hospital with a diffuse pruritic maculopapular rash and a fever. Vital signs were temperature 37.9 °C, blood pressure 146/70 mm Hg, and heart rate 122 beats/min. Significant laboratory test results included a WBC count of 8.9 x 103/mm3 with 24.7% eosinophils, BUN 41 mg/dL, and SCr 3.8 mg/dL. Urine studies showed eosinophiluria and microscopic hematuria; a renal ultrasound was normal. The patient reported taking linezolid for 7 days before losing the prescription bottle 4 days prior to this admission. He reported that the pruritus and rash developed shortly after starting linezolid.
The patient received antihistamines to control symptoms. There was no evidence of skin desquamation or mucosal involvement. SCr remained elevated at 3.6 mg/dL for the first several days of hospitalization. Shortly after admission, the rash began to improve, but the patient remained febrile, with continued eosinophilia. A clinician from the Nephrology service diagnosed the patient with AIN due to eosinophiluria and linezolid exposure. The patient responded to corticosteroids and SCr began to decline on hospital day 8. Blood and urine cultures were negative and intravenous vancomycin was the planned therapy. However, the patient left the hospital against medical advice and did not return.
Discussion. There have been 2 published case reports of AIN related to linezolid.1,2 Our patient had clinical manifestations similar to those in these cases, including maculopapular rash, facial edema, eosinophilia, and elevations in SCr, all of which developed within 1 week of linezolid exposure and responded with supportive care, corticosteroids, and linezolid discontinuation.
According to the Naranjo probability scale, the likelihood of linezolid having caused this reaction is probable.3 The majority of AIN cases are induced by drug therapy.4 With the exception of vancomycin, our patient was not receiving any other classes of drugs that would be suspected of inducing AIN. However, he received vancomycin without complications during both hospitalizations. He did not have any documented previous exposure to linezolid, had the clinical hallmarks of AIN, and responded to therapy for AIN. We cannot exclude the use of contaminated intravenous drugs as a possible cause for this reaction.
Patients receiving linezolid should be closely and routinely monitored for potential adverse events, including AIN.
Footnotes
Financial disclosure: None reported
Letters are subject to review prior to acceptance. They should address areas related to pharmacy practice, research, or education, or articles recently published. Corrections of previously published material also are accepted. Letters are limited to no more than five authors. In cases where adverse effects or drug interactions are described, the Naranjo ADR probability scale (Clin Pharmacol Ther 1981;30:239-45) or DIPS scale (Ann Pharmacother 2007;41:674-80. DOI 10.1345/aph.1H423), respectively, should be used to determine the likelihood that the adverse effect or interaction was drug-related.
References
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