SAN FRANCISCO—Sulfamethoxazole-trimethoprim (SMX-TMP) single-strength twice-weekly provides effective prophylaxis for Pneumocystis jiroveci pneumonia (PJP) in abdominal organ transplant recipients but not for nocardia infections, according to a new study presented at IDWeek 2013.

“Norcardiosis is a very serious complication,” said investigator Costi Sifri, MD, Associate Professor of Medicine in the Division of Infectious Diseases and International Health at the University of Virginia Health System in Charlottesville. “Nocardia infections can involve many different body sites, including the lungs and the brain. They carry a substantial amount of morbidity and mortality and are considered very serious infections.”

Opportunistic infections such as PJP and nocardiosis were significant sources of morbidity and mortality in abdominal organ transplant recipients prior to the use of anti-infective prophylaxis regimens, Dr. Sifri said, and SMX-TMP has proven to be very effective as a prophylaxis agent, particularly for PJP. However, SMX-TMP can cause adverse events that include hyperkalemia, interstitial nephritis, hepatitis, agranulocytosis, and severe cutaneous reactions.

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SMX-TMP regimens for PJP prophylaxis can range from single-strength to double-strength tablets taken daily to three times a week. The minimal dose of SMX-TMP to provide adequate prophylaxis following abdominal organ transplantation has yet to be determined, he said.

Dr. Sifri and his colleagues conducted a retrospective, single-center, cohort study evaluating the prevalence of opportunistic infections in adults undergoing liver, kidney, pancreas, or any multi-organ abdominal transplant from December 2005 to March 2011. Adult patients were included if they had received SMX-TMP single-strength twice weekly within a month of discharge and one-year follow-up or death within a year. The study included 781 transplant patients, of whom 387 were kidney recipients.

The researchers observed no cases of PJP but did observe six cases of nocardiosis (0.77% incidence) in patients during the study period. Five of the six cases of nocardiosis occurred while patients were on SMX-TMP single-strength twice-weekly prophylaxis. The six patients included one liver recipient, two kidney recipients, and three pancreas recipients. All of the pancreas recipients previously had received a kidney transplant.

The rate of nocardiosis on this regimen was much higher than what is reported in the literature (0.1%-0.3% in kidney and liver transplant recipients), he noted. The authors concluded that SMX-TMP single-strength twice-weekly appeared to be effective prophylaxis against PJP infection but may not provide adequate prophylaxis for nocardiosis in abdominal organ transplant recipients.