Objective  To investigate clinical and epidemiological features of pneumocystis jirovecii pneumonia (PJP) in kidney transplant recipients.

  Methods  Clinical data of 68 kidney transplant recipients admitted from July, 2021 to December, 2021 were collected. All patients were divided into the PJP group (n=11), common pulmonary infection group (n=24) and non-pneumonia group (n=33) according to the status of pulmonary infection. The incidence and treatment of PJP after kidney transplantation were analyzed. Basic characteristics and laboratory parameters of the recipients were compared among all groups. The genotyping and transmission map of PJP patients were evaluated.

  Results  Among 64 kidney transplant recipients, 11 cases were definitely diagnosed with PJP. The most common clinical manifestations included elevated body temperature, and dry cough complicated with progressive dyspnea. Chest CT scan showed diffuse interstitial inflammation and ground glass-like lesions of bilateral lungs in all patients. After diagnosis, all patients were orally given with compound sulfamethoxazole for 3-4 weeks. Two patients received non-invasive ventilator-assisted ventilation due to severe lung infection and dyspnea, and the remaining patients were given with nasal cannula oxygenation. One patient experienced elevated serum creatinine level upon discharge, and developed renal allograft failure. The remaining 10 recipients with PJP obtained normal renal allograft function, and no recipient died. Compared with the non-pneumonia group, the rejection rate was higher, the length of hospital stay was longer, the lymphocyte count was less, the lymphocyte proportion was lower, the levels of C-reactive protein, serum creatinine and lactate dehydrogenase were higher, and the levels of serum albumin was lower and CD4⁺T cell count was less in the PJP group (all P < 0.05). Compared with common pulmonary infection group, the lymphocyte count was less, the lymphocyte proportion was lower, the CD4⁺T cell count was less and 1, 3-β-D- glucan (BDG) level was higher in the PJP group (all P < 0.05). No new genotype was detected in 10 of the 12 testing samples. It was considered that PJP mainly depended on two transmission chains and two independent transmission individuals.

  Conclusions  Kidney transplant recipients are prone to pneumocystis jirovecii (PJ) infection due to impaired cellular immune function. The most common clinical manifestations consist of elevated body temperature and dry cough complicated with progressive dyspnea, accompanied by headache and fatigue in partial patients. Chest CT scan shows diffuse interstitial inflammation and ground glass-like lesion of bilateral lungs. PJ may be transmitted through respiratory tract. Small-scale PJP might occur in the follow-up outpatient of kidney transplant recipients. Preventive measures should be delivered in a timely manner.