Antibody responses against Pneumocystis jirovecii in health care workers over time

Pneumocystis jirovecii in the lower respiratory tract of immunocompetent individuals

BACKGROUND

Pneumocystis jirovecii colonization rates in healthy patients are unclear. Previously published studies suggest that the fungus could play a role in the physiopathology and progression of chronic respiratory diseases.

AIMS

The goal of this study was to determine the prevalence of colonization by this fungus in the lower respiratory tract of immunocompetent patients who are not at risk of dysbiosis.

METHODS

The presence of P. jirovecii was confirmed in the bronchoalveolar lavage (BAL) samples from adults who underwent bronchoscopy for non-infectious reasons, had no immunosuppressive factors, and had not been on antibiotic treatment for at least one month. The results were compared with those obtained in the study on the presence of Pneumocystis in environmental dust samples obtained by swabbing surfaces in the participating subjects' domestic settings. Real-time PCR was the technique used for detecting the fungus in both types of samples.

RESULTS

A total of 97 BAL samples and 49 domestic environment samples were studied. The medical reasons for needing a bronchoscopy were, mainly, the examination of both pulmonary neoplasm in 55 patients (57%) and diffuse interstitial lung disease in 21 patients (22%). The overall prevalence of P. jirovecii in our population was 7.22% in BAL samples and 0% in domestic samples.

CONCLUSIONS

The presence of P. jirovecii in the lower respiratory tract is relevantly linked with the patient's immune status, not with an underlying pathology. Prevalence is low in immunocompetent individuals who do not have any infectious pathology and are not having antimicrobial treatments. Our results do not enable us to figure out which the environmental niche of P. jirovecii is.

Pneumocystis jirovecii Disease: Basis for the Revised EORTC/MSGERC Invasive Fungal Disease Definitions in Individuals Without Human Immunodeficiency Virus

BACKGROUND

Pneumocystis jirovecii pneumonia (PCP) causes substantive morbidity in immunocompromised patients. The EORTC/MSGERC convened an expert group to elaborate consensus definitions for Pneumocystis disease for the purpose of interventional clinical trials and epidemiological studies and evaluation of diagnostic tests.

METHODS

Definitions were based on the triad of host factors, clinical-radiologic features, and mycologic tests with categorization into probable and proven Pneumocystis disease, and to be applicable to immunocompromised adults and children without human immunodeficiency virus (HIV). Definitions were formulated and their criteria debated and adjusted after public consultation. The definitions were published within the 2019 update of the EORTC/MSGERC Consensus Definitions of Invasive Fungal Disease. Here we detail the scientific rationale behind the disease definitions.

RESULTS

The diagnosis of proven PCP is based on clinical and radiologic criteria plus demonstration of P. jirovecii by microscopy using conventional or immunofluorescence staining in tissue or respiratory tract specimens. Probable PCP is defined by the presence of appropriate host factors and clinical-radiologic criteria, plus amplification of P. jirovecii DNA by quantitative real-time polymerase chain reaction (PCR) in respiratory specimens and/or detection of β-d-glucan in serum provided that another invasive fungal disease and a false-positive result can be ruled out. Extrapulmonary Pneumocystis disease requires demonstration of the organism in affected tissue by microscopy and, preferably, PCR.

CONCLUSIONS

These updated definitions of Pneumocystis diseases should prove applicable in clinical, diagnostic, and epidemiologic research in a broad range of immunocompromised patients without HIV.

Pneumocystis jirovecii pneumonia in patients receiving tumor-necrosis-factor-inhibitor therapy: implications for chemoprophylaxis

Pneumocystis jirovecii pneumonia (PJP) is an important opportunistic infection that has been increasingly reported in patients with rheumatic disease. Reported incidence among patients taking TNF inhibitors (TNFi) has varied, but has usually been low. Still, disease causes significant mortality among those affected and must be considered in patients with rheumatological disease presenting with dyspnea and cough. Diagnosis can be difficult in the non-HIV population, and our understanding of the epidemiology and natural history after exposure is changing. Trimethoprim-sulfamethoxazole is believed to be the most effective agent for treatment and prophylaxis, but is associated with significant adverse effects. Given the low incidence reported in most studies of patients on TNFi, prophylaxis is probably not beneficial for this patient population as a whole.