Pneumocystis pneumonia outbreak among renal transplant recipients at a North American transplant center: Risk factors and implications for infection control.

BACKGROUND

Pneumocystis pneumonia is a severe opportunistic fungal infection. Outbreaks among renal transplant recipients have been reported in Europe and Japan, but never in North America.

METHODS

We conducted a retrospective case-control study among adult renal transplant recipients at a Canadian center, using a 3:1 matching scheme. Ten cases and 30 controls were matched based on initial transplantation date, and all patients received prophylaxis with trimethoprim-sulfamethoxazole for 1 year posttransplantation.

RESULTS

The median time between transplantation and infection was 10.2 years, and all patients survived. Compared with controls, case patients had statistically lower estimated glomerular filtration rate (29.3 mL/min vs 66.3 mL/min; P = .028) and lymphopenia (0.51 × 10(9)/L vs 1.25 × 10(9)/L; P = .002). Transmission mapping revealed significant overlap in the clinic and laboratory visits among case vs control patients (P = .0002). One hundred percent of patients (4 out of 4) successfully genotyped had the same strain of Pneumocystis jirovecii.

CONCLUSIONS

Our study demonstrated an outbreak of pneumocystis more than 10 years following initial transplantation, despite using recommended initial prophylaxis. We identified low estimated glomerular filtration rate and lymphopenia as risk factors for infection. Overlapping ambulatory care visits were identified as important potential sources of infection transmission, suggesting that institutions should re-evaluate policy and infrastructure strategies to interrupt transmission of respiratory pathogens.