Pneumocystis carinii pneumonia: a review of current issues in diagnosis and management

Development of a Gold Nanoparticle-Based Lateral-Flow Immunoassay for Pneumocystis Pneumonia Serological Diagnosis at Point-of-Care

Pneumocystis jirovecii pneumonia (PcP) is a major human immunodeficiency virus (HIV)-related illness, rising among immunocompromised non-HIV patients and in developing countries. Presently, the diagnosis requires respiratory specimens obtained through invasive and costly techniques that are difficult to perform in all patients or implement in all economic settings. Therefore, the development of a faster, cost-effective, non-invasive and field-friendly test to diagnose PcP would be a significant advance. In this study, recombinant synthetic antigens (RSA) of P. jirovecii's major surface glycoprotein (Msg) and kexin-like serine protease (Kex1) were produced and purified. These RSA were applied as antigenic tools in immunoenzymatic assays for detection of specific anti-P. jirovecii antibodies (IgG and IgM) in sera of patients with (n = 48) and without (n = 28) PcP. Results showed that only IgM anti-P. jirovecii levels were significantly increased in patients with PcP compared with patients without P. jirovecii infection (p ≤ 0.001 with both RSA). Thus, two strip lateral flow immunoassays (LFIA), based on the detection of specific IgM anti-P. jirovecii antibodies in human sera samples, were developed using the innovative association of P. jirovecii's RSA with spherical gold nanoparticles (AuNPs). For that, alkanethiol-functionalized spherical AuNPs with ca. ~40 nm in diameter were synthetized and conjugated with the two RSA (Msg or Kex1) produced. These AuNP-RSA conjugates were characterized by agarose gel electrophoresis (AGE) and optimized to improve their ability to interact specifically with serum IgM anti-P. jirovecii antibodies. Finally, two LFIA prototypes were developed and tested with pools of sera from patients with (positive sample) and without (negative sample) PcP. Both LFIA had the expected performance, namely, the presence of a test and control red colored lines with the positive sample, and only a control red colored line with the negative sample. These results provide valuable insights into the possibility of PcP serodiagnosis at point-of-care. The optimization, validation and implementation of this strip-based approach may help to reduce the high cost of medical diagnosis and subsequent treatment of PcP both in industrialized and low-income regions, helping to manage the disease all around the world.

Circulating genotypes of Pneumocystis jirovecii and its clinical correlation in patients from a single tertiary center in India

The present study was carried out with the objectives of genotyping Pneumocystis jirovecii at three distinct loci, to identify the single nucleotide polymorphisms (SNPs), and to study its clinical implications in patients with Pneumocystis pneumonia (PCP). Analysis of genetic diversity in P. jirovecii from immunocompromised patients was carried out by genotyping at three distinct loci encoding mitochondrial large subunit rRNA (mtLSU rRNA), cytochrome b (CYB), and superoxide dismutase (SOD) using polymerase chain reaction (PCR) assays followed by direct DNA sequencing. Of the 300 patients enrolled in the present study, 31 (10.33%) were positive for PCP by a specific mtLSU rRNA nested PCR assay, whereas only 15 P. jirovecii could be amplified at the other two loci (SOD and CYB). These positives were further subjected to sequence typing. Important genotypic combinations between four SNPs (mt85, SOD110, SOD215, and CYB838) and clinical outcomes could be observed in the present study, and mt85A, mt85T, and SOD110C/SOD215T were frequently associated with "negative follow-up". These SNPs were also noted to be relatively more prevalent amongst circulating genotypes in our study population. The present study is the first of its kind from the Indian subcontinent and demonstrated that potential SNPs of P. jirovecii may possibly be attributed to the clinical outcome of PCP episodes in terms of severity or fatality in different susceptible populations likely to develop PCP during their course of illness.

Serological diagnosis of pneumocystosis: production of a synthetic recombinant antigen for immunodetection of Pneumocystis jirovecii

Diagnosis of Pneumocystis pneumonia (PcP) relies on the detection of P. jirovecii in respiratory specimens obtained by invasive techniques. Thus, the development of a serological test is urgently needed as it will allow the diagnosis of PcP using blood, an inexpensive and non-invasive specimen. This study aims to combine the production of a multi-epitope synthetic recombinant antigen (RSA) and an ELISA test for detection of anti-P. jirovecii antibodies, in order to develop a new approach for PcP diagnosis. The RSA was selected and designed based on the study of the immunogenicity of the carboxyl-terminal domain of the major surface glycoprotein. This antigen was purified and used as an antigenic tool in an ELISA technique for detection of Ig, IgG and IgM antibodies anti-P. jirovecii (patent-pending no. PT109078). Serum specimens from 88 patients previously categorized in distinct clinical subgroups and 17 blood donors, were analysed. The IgM anti-P. jirovecii levels were statistically increased in patients with PcP (p = 0.001) and the ELISA IgM anti-P. jirovecii test presented a sensitivity of 100% and a specificity of 80.8%, when associated with the clinical diagnosis criteria. This innovative approach, provides good insights about what can be done in the future serum testing for PcP diagnosis.

Pneumocystis jirovecii--from a commensal to pathogen: clinical and diagnostic review

Pneumocystis pneumonia is an opportunistic disease caused by invasion of unicellular fungus Pneumocystis jirovecii. Initially, it was responsible for majority of morbidity and mortality cases among HIV-infected patients, which later have been reduced due to the introduction of anti-retroviral therapy, as well as anti-Pneumocystis prophylaxis among these patients. Pneumocystis pneumonia, however, is still a significant cause of mortality among HIV-negative patients being under immunosuppression caused by different factors, such as transplant recipients as well as oncologically treated ones. The issue of pneumocystosis among these people is particularly emphasized in the article, since rapid onset and fast progression of severe symptoms result in high mortality rate among these patients, who thereby represent the group of highest risk of developing Pneumocystis pneumonia. In contrast, fungal invasion in immunocompetent people usually leads to asymptomatic colonization, which frequent incidence among healthy infants has even suggested the possibility of its association with sudden unexpected infant death syndrome. In the face of emerging strains with different epidemiological profiles resulting from genetic diversity, including drug-resistant genotypes, the colonization phenomenon desires particular attention, discussed in this article. We also summarize specific and sensitive methods, required for detection of Pneumocystis invasion and for distinguish colonization from the disease.

Therapeutic potential of caspofungin combined with trimethoprim-sulfamethoxazole for pneumocystis pneumonia: a pilot study in mice

Pneumocystis pneumonia (PcP) is a major cause of mortality and morbidity in immunocompromised patients. There are limited alternative therapeutic choices to trimethoprim-sulfamethoxazole (TMP-SMX) which is the standard first line therapy/prophylaxis for PcP. The efficacy of low doses of caspofungin and caspofungin in association with TMP-SMX standard-prophylactic dose was evaluated in an experimental model of Pneumocystis. Susceptibility of Pneumocystis spp. to low doses of caspofungin and caspofungin/TMP-SMX was evaluated in Balb/c immunosuppressed mice, infected intranasally with P. murina. Caspofungin was administered once daily at 0.1 mg/kg, 0.05 mg/kg, and 0.001 mg/kg and TMP-SMX was administered by oral gavage (12.25 mg/62.5 mg/day), for 21 days. Efficacy was calculated based on the reduction in organism burden determined through quantitative fluorescent-based real-time PCR (qPCR). Serum β-1,3-D-glucan was measured as an additional marker of infection. The present data showed that caspofungin demonstrated anti-Pneumomocystis effect. However, the doses administrated were too low to achieve Pneumocystis eradication, which suggests that echinocandin treatment should not be administrated as mono-therapy. After 21 days of treatment, P. murina was not detected in the lungs of mice with either TMP-SMX or caspofungin/TMP-SMX. The results showed that, even at the lowest concentrations tested, the efficacy of caspofungin in association with TMP-SMX was higher than the efficacy of either drug used alone. The administration of caspofungin/TMP-SMX was at least 1.4 times more effective against P. murina infection than TMP-SMX used alone. The most promising result was achieved with the combination of caspofungin 0.05 mg/kg/day with TMP-SMX 12.5 mg–62.5 mg/day, which reduced the parasite burden to undetectable levels immediately at the 14^th day of treatment, showing a highly marked anti-Pneumomocystis effect. These data suggest that the administration of low doses of caspofungin in combination with low doses of TMP-SMX may provide an improved treatment protocol for Pneumocystis infection clearance.

A hydrophilic-interaction chromatography tandem mass spectrometry method for quantitation of serum s-adenosylmethionine in patients infected with human immunodeficiency virus

BACKGROUND

s-Adenosylmethionine (SAM)1 has been suggested as a diagnostic test and surrogate marker for Pneumocystis jirovecii pneumonia (PCP) in HIV-positive patients. In this study, we report a robust hydrophilic-interaction liquid chromatography tandem mass spectrometry (LC-MS/MS) assay that can be used to quantitate serum SAM in clinical laboratories.

METHODS

Proteins in serum samples were precipitated using trichloroacetic acid. The supernatant was separated after centrifugation. D3d3-SAM was added as the internal standard. SAM and d3-SAM were extracted using a mixed-mode cation exchange column. Extracts were dried under nitrogen and reconstituted in H2O and acetonitrile (1:9, vol:vol). HPLC-tandem mass spectrometry analysis was performed with a silica column and multiple reaction monitoring for SAM and d3-SAM.

RESULTS

The limit of quantitation (LOQ) for SAM was 10 ng/mL. The assay was linear between 10 and 500 ng/mL. Intra-assay coefficient of variation (CV) was 8% and inter-assay CV was 17% at the LOQ. Turnaround time for each specimen was approximately 1 h. Using this method, we found that serum SAM concentration was correlated with fasting status, especially methionine intake. We also measured acute and convalescent serum SAM levels of 8 HIV-positive patients with PCP and non-PCP pneumonia. SAM concentrations in convalescent samples were significantly increased compared to acute levels only in patients with PCP.

CONCLUSIONS

The LC-MS/MS method had sufficient analytical sensitivity for detecting low levels of SAM found in HIV-infected patients and can be used for quantitative measurements in a clinical laboratory. This method facilitates research and possible clinical application of SAM as a marker for PCP.

Pafuramidine for Pneumocystis jiroveci pneumonia in HIV-infected individuals

Pneumocystis jiroveci pneumonia remains one of the major worldwide contributors to the morbidity and mortality of those with HIV infection. The mainstay of therapy for treatment is trimethoprim-sulfamethoxazole (TMP-SMX); however TMP-SMX may be associated with significant side effects and intolerability. In addition, TMP-SMX has a moderate pill burden with three- to four-times daily dosing schedule. Patients unable to tolerate TMP-SMX are confronted with either parenteral therapy or other oral agents that may be less efficacious or are associated with potential serious adverse reactions. Pafuramidine (DB289) is an orally bioavailable prodrug of furamidine (DB75), an investigational diamidine that is less toxic than previous diamidines such as pentamidine. To date, human trials suggest that pafuramidine is well tolerated overall and has clinical activity against Pneumocystis pneumonia. In this article, we review the available data for the use of pafuramidine in Pneumocystis pneumonia.

Pneumocystis pneumonia in patients with HIV infection: clinical manifestations, laboratory findings, and radiological features

Pneumocystis pneumonia (PCP) remains the most common opportunistic infection in patients with acquired immunodeficiency syndrome (AIDS). Familiarity with the clinical features of PCP is crucial for prompt diagnosis, even if the patient is unaware of their HIV serostatus. We describe herein the clinical features of 34 episodes in 32 patients with AIDS-associated PCP and review the existing literature. As for symptoms, the frequency of fever, cough, and dyspnea was 74%, 74%, and 65%, respectively, and the complete triad was present in only 14 of the 34 episodes on first examination. Median duration from onset of symptoms until diagnosis was 3 weeks, and AIDS-associated PCP tended to take an insidious clinical course. Although laboratory findings were generally nonspecific, measurement of beta-D-glucan levels in the serum or plasma was highly useful in the diagnosis of PCP. All but 1 of the patients showed beta-D-glucan levels higher than the cutoff value (median, 147 pg/ml; range, 5-6920 pg/ml). Typical radiographic features of PCP are bilateral, symmetrical ground-glass opacities, but a wide variety of radiographic findings were observed. In our patients, high-resolution computed tomography (HRCT) of the lung showed ground-glass opacities sparing the lung periphery (41% of episodes) or displaying a mosaic pattern (29%), or being nearly homogeneous (24%), ground-glass opacities associated with air-space consolidation (21%), associated with cystic formation (21%), associated with linear-reticular opacities (18%), patchily and irregularly distributed (15%), associated with solitary or multiple nodules (9%), and associated with parenchymal cavity lesions (6%).

Pneumocystis carinii pneumonia in Hong Kong: a 10 year retrospective study

A retrospective review was performed of patients diagnosed with Pneumocystis carinii pneumonia (PCP) from 1994 to 2003 at the Prince of Wales Hospital in Hong Kong. Eighteen patients were identified. Six (33·3 %) were co-infected with human immunodeficiency virus (HIV). The remaining 12 non-HIV-infected patients had underlying diseases: three post-renal transplant recipients, three with haematological malignancies, two with auto-immune diseases, two with renal diseases, one with hepatocellular carcinoma and one with congenital cytomegalovirus disease. Cytomegalovirus co-infection was observed in four patients. All patients received cotrimoxazole therapy, with intolerance observed in four of them, including one with glucose-6-phosphate dehydrogenase deficiency, two with repeated vomiting and one with renal impairment. Overall crude mortality was 33·3 %. The results suggested that, apart from being a common infection for patients with HIV infection, PCP can occur during the course of many immunosuppressive diseases and therapies. The mortality of PCP was high despite appropriate treatment. Chemoprophylaxis should be considered in populations at risk.

S-adenosylmethionine concentrations in diagnosis of Pneumocystis carinii pneumonia

Pneumocystis carinii is unable to synthesise S-adenosylmethionine and thus scavenges this intermediate. We aimed to test whether measurement of concentrations of this metabolic intermediate in plasma could provide a new method for rapid diagnosis of Pneumocystis carinii pneumonia (PCP). We measured S-adenosylmethionine plasma concentrations in 12 healthy controls, 16 patients with confirmed or suspected PCP, and 36 patients with other infections. Median concentration in healthy controls was 106 nmol/L (range 86-128), but the protein was undetectable in eight patients with histologically proven and seven with suspected PCP, and was 8 nmol/L in another confirmed case (p<0.0001). In 36 patients with other infections, S-adenosylmethionine concentrations were much the same as in controls: 18 had bacterial pneumonia, two tuberculosis, five cryptococcal meningitis, three had other infections, and eight had asymptomatic HIV-1 infection. After treatment for PCP, S-adenosylmethionine concentrations rose rapidly in all but one patient who died of the disease. Measurement of plasma S-adenosylmethionine concentrations could prove useful for diagnosis of PCP and assessment of patients' response to treatment.

Prospective cohort study showing changes in the monthly incidence of Pneumocystis carinii pneumonia

Pneumocystis carinii pneumonia (PCP) remains a serious opportunistic infection in HIV infected individuals. Seasonal changes in climate are associated with changes within individual susceptibility to infection. The possibility of monthly variability in the incidence of PCP was therefore examined by means of a cohort study of a database of 8640 HIV infected individuals attending the Chelsea and Westminster Hospital. There were 792 cases of PCP diagnosed since 1985. A marked decline was observed in the incidence of PCP in mid-1992 coincident with the introduction of PCP prophylaxis. There was a further decline in 1996 after the introduction of highly active antiretroviral therapy. Despite no significant monthly variation in the mean attendance to clinic and CD4 count, both new and all cases of PCP were higher in January than in other months (15.9% and 14.5% of all cases, respectively). A correlation with low rainfall in January and new cases of PCP was observed. These data are consistent with an influence of climatic conditions on the presentation of PCP. The diagnosis of PCP is more common in winter months suggesting that this is a transmissible infection.