Detection of Pneumocystis jirovecii by Quantitative PCR To Differentiate Colonization and Pneumonia in Immunocompromised HIV-Positive and HIV-Negative Patients

Abstract

dPneumocystis jirovecii pneumonia (PCP) is an acute and life-threatening lung disease caused by the fungus Pneumocystis jirovecii. The presentation of PCP in HIV-positive patients is well-known and consists of a triad of dyspnea, fever, and cough, whereas the presentation of PCP in HIV-negative patients is atypical and consists of a sudden outbreak, O 2 desaturation, and a rapid lethal outcome without therapy. Despite the availability of direct and indirect identification methods, the diagnosis of PCP remains difficult. The cycle threshold (C T ) values obtained by quantitative PCR (qPCR) allow estimation of the fungal burden. The more elevated that the fungal burden is, the higher the probability that the diagnosis is pneumonia. The purposes of the present study were to evaluate the C T values to differentiate colonization and pneumonia in a population of immunocompromised patients overall and patients stratified on the basis of their HIV infection status. Testing of bronchoalveolar lavage (BAL) fluid samples from the whole population of qPCR-positive patients showed a mean C T value for patients with PCP of 28 (95% confidence interval [CI], 26 to 30) and a mean C T value for colonized patients of 35 (95% CI, 34 to 36) (P < 10 ؊3 ). For the subgroup of HIV-positive patients, we demonstrated that a C T value below 27 excluded colonization and a C T value above 30 excluded PCP with a specificity of 100% and a sensitivity of 80%, respectively. In the subgroup of HIV-negative patients, we demonstrated that a C T value below 31 excluded colonization and a C T value above 35 excluded PCP with a specificity of 80% and a sensitivity of 80%, respectively. Thus, qPCR of BAL fluid samples is an important tool for the differentiation of colonization and pneumonia in P. jirovecii-infected immunocompromised patients and patients stratified on the basis of HIV infection status with different C T values.

Reliable differentiation of Pneumocystis pneumonia from Pneumocystis colonisation by quantification of Major Surface Glycoprotein gene using real‐time polymerase chain reaction

“…One study proposed that patients of inflammatory rheumatic arthritis and Wegener's granulomatosis should be treated for PJ colonisation before initiating immunosuppressive therapy, as there was growing evidence that these colonizers may infect other immunosuppressed patients in the ward . This grey area had been documented by other researchers also . Till a better multi‐centre study resolves the problem, the decision to treat or not‐to‐treat these patients may be left to the clinician depending upon clinical correlations and serological markers …”

“…Although conventional PCR can improve sensitivity of detection, it cannot differentiate the disease from colonisation in the absence of quantification. These challenges have been addressed with various real‐time quantitative PCRs, using different target genes and methodologies . The interpretation of these qPCRs, however, remain confusing owing to several contrasting variables thereby hindering reliable fungal burden estimation.…”

Influenza and Pneumocystis jirovecii pneumonia in an allogeneic hematopoietic stem cell transplantation recipient: Coinfection or superinfection?

“…PJP can be diagnosed by identification on respiratory samples of cysts using various stains or by indirect immunofluorescence. Pneumocystis PCR on respiratory samples is another very sensitive method for diagnosis of PJP in non‐HIV patients, given the lower pathogen load in this patient population . Also of importance, despite the reported high mortality associated with PJP infection in immunocompromised non‐HIV patients and similarly in the case of influenza LRTI, this case demonstrated a good outcome with prompt and appropriate antimicrobial therapy and aggressive supportive care.…”

LOW CD4 LYMPHOCYTE COUNT RELATED RISK TO Pneumocystis jiroveci PNEUMONIA IN HIV/AIDS PATIENTS FROM BRONCHOALVEOLAR LAVAGE SPECIMENS USING REAL TIME PCR DETECTION

“…16 Cycle threshold value positively correlated with the microorganism density in the sample. 17 A cut off CT value of 32 cycle can be applied in differentiating colonization to P. jiroveci infection with sensitivity 72% and specificity 75%. 17 CD4 lymphocyte count and P. jiroveci as an agent of pneumonia show significant relationship with p value 0.002.…”