Monoclonal antibody to detect Pneumocystis carinii

Quantitative PCR to Discriminate Between Pneumocystis Pneumonia and Colonization in HIV and Non-HIV Immunocompromised Patients

Pneumocystis pneumonia (PCP) is an opportunistic infection that commonly occurs in immunocompromised individuals. A definite diagnosis of PCP can be made only when the organism is identified in a respiratory specimen. It remains unclear whether qPCR can differentiate patients with PCP from those with Pneumocystis jirovecii colonization. In this study, we retrospectively collected data from HIV and non-HIV patients during 2013-2019. A diagnosis of definite, probable PCP, or PCP excluded was made based on clinical criteria, radiological reports, and three standard laboratory staining methods with blinding to qPCR data. Data from qPCR that was performed to determine the fungal burden (DNA copies/μl) in the BAL specimens of 69 HIV and 286 non-HIV patients were then obtained and reviewed. Receiver Operating Characteristic (ROC) curve analysis was performed to determine the upper and lower cut-off values for PCP diagnosis in HIV and non-HIV groups. In the non-HIV group, the lower cut-off value of 1,480 DNA copies/μl yielded a sensitivity of 100% (95% confidence interval [CI], 91.0-100), specificity of 72.9% (95% CI, 64.0-80.7), a positive predictive value (PPV) of 54.9% (95% CI, 47.6-62.1), and a negative predictive value (NPV) of 100% with Youden index of 0.73 for PCP diagnosis. In this group, the upper cut-off value of 9,655 DNA copies/μl showed the sensitivity of 100% (95% CI, 91.0-100) and specificity of 95.8% (95% CI, 90.4-98.6) with PPV of 88.6% (95% CI, 76.8-94.8) and a NPV of 100% with Youden index of 0.96 for PCP diagnosis. Regarding the HIV group, the lower cut-off value of 1,480 DNA copies/μl showed the sensitivity of 100% (95% CI, 92.5-100%) and specificity of 91.7% (95% CI, 61.5-99.8) with PPV of 97.9% (95% CI, 87.8-99.7) and a NPV of 100% with Youden index of 0.92 for PCP diagnosis. The sensitivity and specificity of the upper cut-off value of 12,718 DNA copies/μl in this group were 97.9% (95%CI, 88.7-100) and 100% (95%CI, 73.5-100), respectively. The values above the upper cut-off point had a PPV of 100% (95% CI, N/A) and a NPV of 92.3% (95% CI, 63.3-98.8) with Youden index of 0.98 for PCP diagnosis in the HIV group.

Cytologic examination of bronchoalveolar lavage fluid from immunosuppressed patients

Pulmonary infiltrates in immunocompromised patients frequently represent infections. This study was undertaken to evaluate cytologic examination of bronchoalveolar lavage samples and the value of different preparations and silver staining. Over 6 mo, 336 samples were collected from 155 immunosuppressed patients in whom both cytologic and microbiologic studies were performed. In 27 samples, the cytology, microbiology or both demonstrated the presence of infectious agents. In four cases, cytology identified neoplastic process. Cytology had a sensitivity of 34.6% for detection of infection, which increased to 42.9% when Cytomegalovirus was excluded. Cytology detected 6 of 15 cases of Aspergillus, including three cases not detected by microbiology and 3 of 4 cases of Pneumocystis, but did not identify any of the Cytomegalovirus cases. The type of preparations did not affect detection of the organism when present in cytologic samples and silver staining did not appear to have added value in examination of these samples.

Immunodetection of Pneumocystis carinii in bronchoalveolar lavage specimens compared with methenamine silver stain

Immunodetection of Pneumocystis carinii, based on immunofluorescence and use of a monoclonal antibody specific for an antigen located within the cyst wall and detectable after trypsin digestion only, was compared with a methenamine silver stain in 553 bronchoalveolar lavage specimens from immunosuppressed patients. P. carinii was found by immunofluorescence in 72 (86%) and by silver stain in 68 (81%) of the total of 84 positive samples detected by either or both of these methods.

Why have Pneumocystis carinii trophozoites been ignored?

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Pneumocystis carinii pneumonia: detection of parasites in sputum and bronchoalveolar lavage fluid by monoclonal antibodies

Diagnosis of pneumocystis pneumonia is based on identifying Pneumocystis carinii cytochemically in material from the lung. The silver methenamine staining methods most commonly used are technically difficult and lack specificity. The diagnostic value of immunocytological identification of the parasite was evaluated by using mouse monoclonal antibody 3F6, specific for human pneumocystis, to identify P carinii in bronchoalveolar lavage fluid and sputum by immunofluorescence and was compared with that of other variables. Bronchoalveolar lavage was performed on 25 patients positive for HIV antibody with clinically suspected pneumocystis pneumonia and 40 patients negative for HIV antibody who presented with interstitial disorders of the lung. Lavage fluid showed pneumocystis only in the patients positive for antibody, the parasite being detected in 19 by immunofluorescence and in 17 by a modified silver methenamine staining method. Chest x ray films obtained at the time of bronchoscopy showed interstitial or alveolar shadowing in 17 of the 19 patients, but clinical symptoms and the presence of antibodies to pneumocystis did not seem to be predictive. Sputum samples were collected during 43 episodes of clinically suspected pneumocystis pneumonia in patients positive for HIV antibody. Pneumocystis was detected consistently more commonly by immunofluorescence than the silver strain in sputum collected routinely and induced by inhalation of saline. In 17 patients bronchoalveolar lavage followed sputum collection, and the sensitivity of detection of pneumocystis in immunofluorescence in sputum compared with lavage fluid was 57% (8/14). Immunofluorescence was suitable for specimens fixed in ethanol and seemed highly specific and more sensitive than the standard cytochemical methods for identifying pneumocystis.

Asian mothers' risk factors for perinatal death--the same or different? A 10 year review of Leicestershire perinatal deaths

A case-control study of all perinatal deaths in Leicestershire was established in 1976. By 1985 some 1342 singleton perinatal deaths had occurred. Perinatal mortality among patients of Asian origin was consistently higher than that among European women. Many of the sociomedical risk factors for perinatal death known at booking were common to both population groups. In this population of Asian women, however, low social class was not associated with perinatal risk and illegitimacy hardly ever occurred. In contrast, previous infertility among the Asian women was associated with risk of perinatal death, while no such association was found with European women. In 19% of perinatal deaths care was either inadequately provided or taken up. The case-control design in these circumstances provides a practicable way to evaluate causal factors and at the same time to provide information of value to educators and health service planners.

Observations favouring Pneumocystis carinii pneumonia as a primary infection: a monoclonal antibody study on paraffin sections

Pneumocystis carinii pneumonia is characteristic of immunodeficiency and the organism is probably acquired during early childhood. Since infection is only manifest in the lungs, it has been presumed that the organism lies dormant in these tissues following the primary infection. Conventional staining procedures have, however, failed in the absence of pneumonia to demonstrate consistently any forms of Pneumocystis carinii. To study this problem further, lung sections and hilar lymph nodes from immunodepressed adults with and without Pneumocystis carinii pneumonia as well as lung sections from presumed immunocompetent patients were examined for the cyst and trophozoite forms of Pneumocystis carinii using a monoclonal antibody. The organism was only identified in areas of pneumonia, and the source of the organism in these patients may therefore be a new infection with a different human subtype and not, as previously thought, reactivation of a primary infection.

Detection of Pneumocystis carinii in lung-derived samples using monoclonal antibodies to an 82 kDa parasite component

Monoclonal antibodies against Pneumocystis carinii (PC) antigenic epitopes resistant to denaturing procedures were developed by immunization of mice with isolated parasites and a urea extract of infected human lung tissue. Paraffin sections of infected lung tissue were used as antigen in the screening for reactive clones. The target antigen was identified as an 82 kDa parasite specific component in immunoblotting. The antibody showed no cross-reactivity with human lung tissue and various rat tissues and failed to react with a number of parasites and fungi. The antigenic epitope recognized by the anti-82 kDa component was resistant to denaturing procedures involved in fixation and processing of tissues for histology. The antibodies could be used for identification of both cysts and trophozoites in fixed smears of infected lung tissue and bronchoalveolar lavage fluid from infected individuals.