Increased dosage of infliximab is a potential cause of Pneumocystis carinii pneumonia
© Iwama et al. 2016
Received: 13 December 2015
Accepted: 18 January 2016
Published: 2 February 2016
Pneumocystis carinii pneumonia occasionally appears in immunodeficient patients. While several reports have shown that Pneumocystis carinii pneumonia occurred in the early phase of starting infliximab treatment in patients with Crohn’s disease (CD), the present case suggests for the first time that an increased dosage of infliximab may also lead to pneumonia.
A 51-year-old male had been taking 5 mg of infliximab for the treatment of CD for 10 years with no adverse events. Beginning in September 2013, the dose of infliximab had to be increased to 10 mg/kg because his status worsened. Thereafter, he complained of a fever and cough, and a CT scan revealed ground-glass opacities in the lower lobes of the bilateral lung with a crazy-paving pattern. Bronchoscopy detected swelling of the tracheal mucosa with obvious dilations of the vessels. A polymerase chain reaction using a bronchoalveolar lavage fluid sample detected specific sequences for Pneumocystis jirovecii; thus he was diagnosed with Pneumocystis carinii (jirovecii) pneumonia. After discontinuing infliximab and starting antibiotic treatment, his symptoms and CT findings were dramatically improved.
The administration of an increased dosage of infliximab can cause Pneumocystis carinii pneumonia in CD patients.
Pneumocystis carinii pneumonia occasionally appears in immunodeficient patients, particularly with the administration of chemotherapy. While several reports have shown that infliximab treatment [1–5], which is generally used for the treatment of rheumatoid arthritis and Crohn’s disease, can lead to Pneumocystis carinii pneumonia [6–12], to the best of our knowledge, no case has demonstrated the development of pneumonia due to an increased dosage of infliximab treatment. The present case suggests that an increased dosage of infliximab is a potential cause of Pneumocystis carinii pneumonia.
Date on pneumocystis pneumonia during administrarion of infliximab
Age at diagnosis (years)
Crohn’s disease duration
Dose of IFX
Seddik et al. 
PSL + AZA
2 weeks alive
Velayos et al. 
2 years 3 months
ST + PSL
2 weeks alive
Kaur et al. 
ST + PM
1 month died
Stratakos et al. 
mPSL + AZA
6 month alive
Itaba et al. 
PSL + AZA
ST + mPSL
4 month alive
金井 et al. 
5-ASA + PSL
ST + mPSL
6 month alive
Tshudy et al. 
4 weeks alive
6-MP (0.15 g/day)
1 year 5 month alive
Of the seven cases, five were male and two were female. The age ranged from 8 to 77 years. While Pneumocystis carinii pneumonia appeared at 4 weeks to 29 months after starting infliximab treatment in previous reports, the present case exhibited pneumonia at 120 months after starting infliximab treatment, at 102 months after starting the 6-mercaptopurine treatment, 24 weeks after starting an increased dosage of infliximab from 5 to 10 mg/kg. This suggests that an increased dosage of infliximab is a potential cause of immunodeficiency, leading to Pneumocystis carinii pneumonia. Notably, all cases developing Pneumocystis carinii pneumonia took immunomodulators and/or steroids, suggesting that the combined use of these drugs is a risk for pneumonia. Because sulfamethoxazole/trimethoprim was effective for all cases, antibiotics should be immediately administered after the diagnosis of Pneumocystis carinii pneumonia.
The findings of the present case suggest that the administration of an increased dosage of infliximab, as well as a general dose of infliximab, can cause Pneumocystis carinii pneumonia in CD patients, particularly in patients taking immunomodulators and/or steroids, illustrating the need for follow up, including pulmonary symptoms and CT examinations, when increasing the dosage of infliximab in CD patients.
Written informed consent was obtained from the patient for publication of this case report and accompanying images.
TI and AS were equally contributed to this study. TI, AS and MF conceived the report, collected data, and wrote the first draft of the report. AS and KT followed up the patient. YN, NU and SK performed endoscopy and evaluated the disease severity. SF, TG and JS evaluated radiological images including computed tomography. KM and IK supervised the study. All authors contributed to the critical revision of the report for important intellectual content. All authors read and approved the final manuscript.
We would like to thank Dr. Yuhei Inaba for his excellent suggestion and Dr. Tatsuya Utsumi and Dr. Hiroki Sato for significant assistances.
The authors declare that they have no competing interests.
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