Pneumocystis carinii colonization in the absence of immunosuppression

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.

In vitro antibacterial and cytotoxic activity of leaf extracts of Centella asiatica (L.) Urb, Warburgia salutaris (Bertol. F.) Chiov and Curtisia dentata (Burm. F.) C.A.Sm - medicinal plants used in South Africa

Background

Compounds having both anticancer and antimicrobial activity have promising therapeutic potential due to their selective cytotoxicity and their potential to reduce the occurrence of bacterial and fungal infections in immune-compromised cancer patients. In our quest to find new antimicrobial agents with potent anticancer activity, the biological potential of leaves from the three medicinal plants Centella asiatica, Warburgia salutaris and Curtisia dentata as used by Zulu traditional healers for the treatment of cancer is investigated.

Methods

Extracts were assayed for antibacterial activity using the agar well diffusion and micro plate dilution assay. In addition, minimum bactericidal concentrations (MBC), lactate dehydrogenase (LDH) release assay and rhodamine 6G intake assay were used to ascertain the antibacterial activity. The cytotoxic effects of the plant extracts were determined using tetrazolium-based colorimetric (MTT) cell proliferation assay against MCF-7, human colorectal carcinoma cells (Caco-2), A549 and HeLa cancerous cell lines.

Results

The acetone extracts from Waburgia salutaris revealed noteworthy anti-proliferative effect yielding IC₅₀ value of 34.15 μg/ml against MCF-7 cell line, while acetone extract from Curtisia dentata significantly (P ≤ 0.05) revealed promising IC₅₀ values of 41.55, 45.13, 57.35 and 43.24 μg/ml against A549, HeLa, CaCo-2 and MCF-7 cell lines. The extracts further revealed a broad-spectrum antibacterial activity against bacterial strains used in the study. An acetone extract from W. salutaris revealed the highest zone of inhibition and the lowest minimum inhibitory concentration (MIC) of 21.0 mm and 0.16 mg/ml respectively against Staphylococcus aureus. Methanol extract from W. salutaris and ethyl acetate extract from C. dentata revealed 53% inhibition of R6G inside the cell against Staphylococcus aureus and Escherichia coli respectively in a cytosolic lactate dehydrogenase assay, suggesting that the mode of action of such extracts may be through efflux pump.

Conclusions

Overall, the extracts had good antibacterial activity and anti-proliferative effects against selected cancerous cell lines. Given the good antibacterial activity of the extracts the plants may act as an immune booster and prevent infection in immunosuppressed cancer patients. This is further supported by the plants’ anti-proliferative potential, bacteriostatic, bactericidal properties and also their ability to block bacterial efflux pump systems.

A study on the colonization of Pneumocystis jirovecii among outpatients during cancer chemotherapy and among healthy smokers

AIMS

Pneumocystis Jirovecii (PJ) is regarded as an agent of fungal infection and in cases of pneumocystis pneumonia (PCP) in immune-compromised patients including cancer patients. It is not clear what kinds of cancer, treatments, and environment need prophylaxis for PCP. In this study, we have analyzed the detectability of PJ DNA from sputum, and discussed prophylaxis and risk factors regarding PCP.

METHODS

A total of forty-nine materials (twenty-four from outpatients during cancer chemotherapies and twenty-five from healthy control subjects) was collected. Their PJ DNAs were amplified using nested PCR with specific primers of the PJ gene (the mitochondrial small subunit rRNA gene).

RESULTS

PJ DNA was detectable in 46% of specimens (sputum) from cancer patients during chemotherapies, and incidences of not significantly different among types of cancer and chemotherapy regimens. Prophylactic use of Sulfamethoxazole/Trimetoprim (ST) reduced the detection of PJ DNA. Detection of PJ DNA is not high among healthy non-smokers (20%) and high among healthy smokers (47%).

CONCLUSIONS

Prophylactic use of ST may be necessary for cancer patients during chemotherapies. Also, smoking may be associated with PJ colonization in the airway and air vesicles, and may increase the mortality rate for PCP. All patients undergoing cancer chemotherapies should cease smoking.

Pneumocystis jirovecii Pneumonia in Rheumatoid Arthritis Patients: Risks and Prophylaxis Recommendations

Pneumocystis jirovecii infection causes fulminant interstitial pneumonia (Pneumocystis pneumonia, PCP) in patients with rheumatoid arthritis (RA) who are receiving biological and/or nonbiological antirheumatic drugs. Recently, we encountered a PCP outbreak among RA outpatients at our institution. Hospital-acquired, person-to-person transmission appears to be the most likely mode of this cluster of P. jirovecii infection. Carriage of P. jirovecii seems a time-limited phenomenon in immunocompetent hosts, but in RA patients receiving antirheumatic therapy, clearance of this organism from the lungs is delayed. Carriers among RA patients can serve as sources and reservoirs of P. jirovecii infection for other susceptible patients in outpatient facilities. Development of PCP is a matter of time in such carriers. Considering the poor survival rates of PCP cases, prophylactic antibiotics should be considered for RA patients who are scheduled to receive antirheumatic therapy. Once a new case of PCP occurs, we should take prompt action not only to treat the PCP patient but also to prevent other patients from becoming new carriers of P. jirovecii. Short-term prophylaxis with trimethoprim-sulfamethoxazole is effective in controlling P. jirovecii infection and preventing future outbreaks of PCP among RA patients.

Diagnostic value of direct fluorescence antibody staining for detecting Pneumocystis jirovecii in expectorated sputum from patients with HIV infection

Direct fluorescent antibody (DFA) staining of induced sputum is frequently used to diagnose Pneumocystis pneumonia (PCP) in patients infected with human immunodeficiency virus, although induction can provoke nausea and bronchospasm. Since the diagnostic value of expectorated sputum examined with DFA stain has not been well evaluated, we reviewed the medical records of HIV-infected patients who were clinically diagnosed as having PCP between 1999 and 2011. Over this 13-year period, we found 76 patients whose records included the results of DFA staining of expectorated sputum and noted that 42 (55.3%) were positive. Polymerase chain reaction to detect Pneumocystis in the sputum of 65 of the patients resulted in the finding of 43 (66.2%) who were positive. Our findings suggest that DFA staining of expectorated sputum could be a useful initial diagnostic method in HIV-infected patients with PCP.

Pneumocystis jirovecii infection: an emerging threat to patients with rheumatoid arthritis

Accompanying the increased use of biologic and non-biologic antirheumatic agents, patients with RA have been exposed to an increased risk of Pneumocystis jirovecii infection, which causes acute fulminant P. jirovecii pneumonia (PCP). Mortality in this population is higher than in HIV-infected individuals. Several guidelines and recommendations for HIV-infected individuals are available; however, such guidelines for RA patients remain less clear. Between 2006 and 2008 we encountered a clustering event of P. jirovecii infection among RA outpatients. Through our experience with this outbreak and a review of the recent medical literature regarding asymptomatic colonization and its clinical significance, transmission modes of infection and prophylaxis of PCP, we have learned the following lessons: PCP outbreaks among RA patients can occur through person-to-person transmission in outpatient facilities; asymptomatic carriers serve as reservoirs and sources of infection; and short-term prophylaxis for eradication of P. jirovecii is effective in controlling PCP outbreaks among RA outpatients.

Molecular diagnosis and detection of Pneumocystis jirovecii DHPS and DHFR genotypes in respiratory specimens from Colombian patients

A total of 98 respiratory specimens from 88 patients suspected of having Pneumocystis jirovecii pneumonia (PcP) were evaluated using a previously reported nested polymerase chain reaction (PCR) assay for mitochondrial large subunit rRNA (mtLSUrRNA). In addition, samples from patients with other pulmonary infections and a sizeable DNA collection from other fungal pathogens were studied. A panfungal PCR assay amplifying the ITS1-ITS2 regions were also used to identify all fungal DNAs. All samples positive for mtLSUrRNA-PCR were evaluated to determine mutations in dihydropteroate synthase (DHPS) and dihydrofolate reductase (DHFR) genes. All PCR-amplified products were sequenced. Of the 98 clinical specimens, 13 (13.2%) were positive by GMS stain and mtLSUrRNA-PCR, while 32 (32.6%) that were GMS stain-negative gave positive results with mtLSUrRNA-PCR. All the sequences corresponding to the 45 products amplified by mtLSUrRNA-PCR showed 99% or greater identity with P. jirovecii. The mtLSUrRNA-PCR exhibited 86% sensitivity and 98% and 96.6% specificity when results were compared to those corresponding to negative controls and other proven clinical entities, respectively. We found mutations in the DHPS gene in 3 (7.7%) patients, 2 located at codon 55 and 1 at codon 57. One patient showed a synonymous substitution at nucleotide position 312 in the DHFR gene. These results suggest that mtLSUrRNA-PCR is a useful test for diagnosing PcP. In contrast to other studies, this study found a low prevalence of mutations in the DHPS and DHFR genes in Colombian patients.

Asymptomatic carriage of Pneumocystis jiroveci in elderly patients with rheumatoid arthritis in Japan: a possible association between colonization and development of Pneumocystis jiroveci pneumonia during low-dose MTX therapy

Low-dose methotrexate (MTX) has been used effectively for rheumatoid arthritis (RA) because of its favorable risk-benefit ratio. One of the recent concerns arising from this therapy is a possible increase in the rate of opportunistic infections, particularly Pneumocystis jiroveci pneumonia (PCP). In this study, we report two cases of PCP occurring during low-dose methotrexate therapy for RA and review 13 additional cases from the literature on Japanese patients with RA. The average age of these patients was 67.7 years, and most were over the age of 60. MTX-associated PCP appears to occur more frequently in elderly individuals in Japan. To identify individuals with a high risk of PCP, we performed a polymerase chain reaction on specimens from induced sputum or bronchoalveolar lavage fluids from 55 patients with RA. At that point in time, they showed no evidence of PCP development. We found six patients (10.9%) having asymptomatic carriage of P. jiroveci. The mean age of the P. jiroveci-positive patients was 74.7 years, which was significantly older than the P. jiroveci-negative patients (mean age 63.6 years). Of the RA patients over the age of 65, 18.8% (6 cases out of 32) were carriers of P. jiroveci. There were no significant differences in RA duration or counts of white blood cells or lymphocytes between the positive and negative groups. Notably, we encountered a case of PCP occurring in an asymptomatic carrier of P. jiroveci during low-dose MTX therapy for RA. This case appeared to be a reactivation of latent infection. By careful follow-up on the carriers of P. jiroveci, we succeeded in promptly diagnosing PCP, and we employed the appropriate therapeutic strategies for this possibly life-threatening complication.

Apparent Absence of Pneumocystis jirovecii in Healthy Subjects

We prospectively investigated 30 healthy subjects with normal CD4+ T cell counts in blood and normal findings of spirometry and chest radiography for the presence of Pneumocystis jirovecii, by performing polymerase chain reaction on sputum specimens. Fifty patients with chronic obstructive pulmonary disease were investigated at the same time in the same manner; this group was used as controls for the diagnosis of pulmonary colonization with P. jirovecii. None of the healthy subjects had positive test results, whereas the fungus was detected in 8 patients with chronic obstructive pulmonary disease. The results suggest that in our region (Amiens, France), P. jirovecii is apparently uncommon in healthy subjects and that this population, therefore, plays a minor role in circulation of the fungus within human communities.

Genotypic variation in Pneumocystis jirovecii isolates in Britain

BACKGROUND

Pneumocystis jirovecii is the cause of Pneumocystis pneumonia (PCP) in immunosuppressed humans. Asymptomatic colonisation with P jirovecii may occur in patients with minor immunosuppression or chronic lung disease. The aim of this study was to describe the molecular epidemiology of P jirovecii in Britain over a period of 12.5 years.

METHODS

Between January 1989 and July 2001 161 samples of P jirovecii were obtained from patients with PCP (n = 119), patients colonised by P jirovecii (n = 35), and from air spora (n = 6). Genotyping of samples was performed at the mitochondrial large subunit rRNA (mt LSU rRNA).

RESULTS

Genotype 1 (38%) was the most frequently identified genotype: genotypes 2 (26.6%), 3 (20.3%), and 4 (5%) were less common. Mixed infection (more than one genotype) was identified in 10% of samples. While genotype 1 was the most frequently detected type in both patients with PCP and those colonised by P jirovecii (38% and 42%, respectively), these groups differed in the relatively lower rate of detection of genotype 4 (2% v 17%) and the higher detection of mixed infection in those with PCP (13% v 3%). Detection of specific genotypes of P jirovecii was associated with the patient's place of residence (p = 0.02). There was no association between specific genotypes and severity of PCP as measured by arterial oxygen tension (p = 0.3).

CONCLUSIONS

The evidence of clustering of specific genotypes with patient's postcode of residence is consistent with the hypothesis of person to person transmission of P jirovecii via the airborne route. The lack of association between specific mt LSU rRNA genotypes and severity of PCP suggests that this locus is not implicated in the virulence of the organism.

Is Pneumocystis carinii pneumonia after stem cell transplantations a contagious disease?

We report of twins who underwent hematopoietic stem cell transplantation (HSCT) for neonatal acute leukemia. Hospitalized in the same room from the time the first one demonstrated respiratory symptoms, they both developed Pneumocystis jiroveci (formerly carinii) pneumonia (PCP) 2 wk apart. This observation suggests that PCP may be a contagious disease in HSCT recipients. This may be especially true for infants and young children who are at risk of primary P. jiroveci infection, and should be avoided.

Immunoglobulin G Fc(gamma) receptor expression on polymorphonuclear cells in bronchoalveolar lavage fluid of HIV-infected and HIV-seronegative patients with bacterial pneumonia

This study was designed to test the hypothesis that impaired neutrophil function might contribute to the development of bacterial pneumonia in patients with HIV-infection. Numbers of inflammatory cells and immunoglobulin G Fcgamma receptor (IgG FcgammaR) I, II, III levels were investigated in bronchoalveolar lavage (BAL) fluid of HIV-seronegative and HIV-infected patients with bacterial pneumonia. The 99 patients were classified into three groups: I: HIV-seronegative and pneumonia (n = 40); II: HIV-infected and pneumonia (n = 19); III: HIV-seronegative with other pulmonary diseases than pneumonia (n = 40). The results of groups I and II, II and III, and I and III were compared. The percentage of alveolar macrophages was significantly lower (group II vs. III: p = 0.005, group I vs. III: p = 0.001), that of neutrophils increased significantly in patients with pneumonia (group II vs. III: p = 0.02, group I vs. III: p = 0.01). Lymphocytes differed only between groups I and III (p = 0.04). Although only the expression of FcgammaRI was significantly higher in HIV-seronegative pneumonia patients compared to those without pneumonia (p = 0.01), the mean expression of all three receptors was lower in the HIV-infected group, with that of FcgammaRI approaching statistical significance. This report provides first evidence that altered FcgammaR expression on BAL neutrophils might contribute to the increased susceptibility of HIV-infected patients to bacterial pneumonia.

Pneumocystis jirovecii dihydropteroate synthase genotypes in immunocompetent infants and immunosuppressed adults, Amiens, France

To date, investigations of Pneumocystis jiroveci circulation in the human reservoir through the dihydropteroate synthase (DHPS) locus analysis have only been conducted by examining P. jirovecii isolates from immunosuppressed patients with Pneumocystis pneumonia (PCP). Our study identifies P. jirovecii genotypes at this locus in 33 immunocompetent infants colonized with P. jirovecii contemporaneously with a bronchiolitis episode and in 13 adults with PCP; both groups of patients were monitored in Amiens, France. The results have pointed out identical features of P. jirovecii DHPS genotypes in the two groups, suggesting that in these two groups, transmission cycles of P. jirovecii infections are linked. If these two groups represent sentinel populations for P. jirovecii infections, our results suggest that all persons parasitized by P. jirovecii, whatever their risk factor for infection and the form of parasitism they have, act as interwoven circulation networks of P. jirovecii.

Pneumocystis jiroveci isolates with dihydropteroate synthase mutations in patients with chronic bronchitis

Since mutations in the dihydropteroate synthase (DHPS) gene possibly associated with sulfonamide resistance have been reported in patients with Pneumocystis jiroveci (previously carinii) pneumonia, and since P. jiroveci colonization has been recently demonstrated in patients with chronic pulmonary diseases, the present study aimed to investigate the possible occurrence of P. jiroveci DHPS mutations in patients with chronic bronchitis. P. jiroveci colonization was detected in 15 of 37 non-selected patients with chronic bronchitis by amplifying the large subunit of the mitochondrial gene of the ribosomal RNA using nested PCR. DHPS mutations were demonstrated using touchdown PCR and restriction enzyme analysis in two of eight patients with chronic bronchitis and in two of six patients from the same region who had AIDS-associated Pneumocystis pneumonia. In all cases, mutations were observed in subjects with no prior exposure to sulfonamides. These data could have important implications for public health, since (i) P. jiroveci colonization could speed the progression of chronic bronchitis, and (ii) these patients, who are customary sputum producers, could represent a reservoir for sulfonamide-resistant strains with the potential ability to transmit them to immunocompromised hosts susceptible to Pneumocystis pneumonia.

Similar genotypes of Pneumocystis jirovecii in different forms of Pneumocystis infection

This study describes the genotyping of Pneumocystis jirovecii organisms isolated from three groups of patients that developed diverse forms of P. jirovecii infection; the patients were monitored in the same French hospital. Forty archival specimens from 13 adults with Pneumocystis pneumonia, eight adults colonized by P. jirovecii and 19 immunocompetent infants infected with the fungus contemporaneously with a bronchiolitis episode were analysed retrospectively. Genotyping was performed by analysis of sequences of the internal transcribed spacer (ITS)1 and ITS2 regions, and of the dihydropteroate synthase (DHPS) locus. At the ITS regions, a high diversity of genotypes, identical main genotypes (B1a3 and B2a1) and the occurrence of mixed infections (more than one genotype) were observed in the three patient groups. At the DHPS locus, the results indicated the presence of mutants in the two adult groups, as well as in the infant group. Consequently, at these two independent genomic regions, P. jirovecii isolates from patients who developed different forms of infection and who lived in the same geographical region presented common characteristics. These results suggest that patients infected with P. jirovecii, whatever the form of infection they present, are part of a common human reservoir for P. jirovecii.

Association between human-Pneumocystis infection and small-cell lung carcinoma

BACKGROUND

Tobacco smoking is the most important but not the only risk factor in lung carcinoma. There is evidence that certain infections, which cause chronic inflammatory reactions, can also induce tumour development. It has recently been shown that patients with chronic pulmonary diseases present a high rate of subclinical Pneumocystis infection, and that the latter is able to induce inflammatory responses and alveolar cell alterations. The possible role of Pneumocystis infection in the development of lung neoplasms thus deserves consideration.

MATERIAL AND METHODS

Polymerase chain reaction has been used to analyze the presence of DNA of two independent loci of the Pneumocystis genome: the mitochondrial region (mtLSU rRNA) and the gene encoding for the dihydropteroate synthase enzyme, in paraffin-embedded tissue blocks of 10 cases of small cell lung carcinoma (SCLC) and 10 cases of nonsmall cell lung carcinoma (NSCLC) with similar demographic and clinical characteristics. Five cases without lung pathology, and two cases of Pneumocystis pneumonia were also analyzed as controls.

RESULTS

DNA of the microorganism was found in all the cases of SCLC but in only two of the NSCLC, and in none of the controls without pulmonary disease - thus implying a statistically significant association (P < 0.0001) between subclinical Pneumocystis infection and SCLC.

CONCLUSIONS

While the nature of this association is not clear, it nevertheless constitutes an important finding - either the infection is specifically facilitated by this tumour or induces the development of this type of neoplasm in combination with other factors. Eur J Clin Invest 2004; 34 (3): 229-335

Asymptomatic carriage of Pneumocystis jiroveci in subjects undergoing bronchoscopy: a prospective study

BACKGROUND

The opportunistic fungus Pneumocystis jiroveci is a common cause of respiratory infection in immunocompromised patients. By contrast, pneumocystis pneumonia (PCP) occurs only rarely in immunocompetent individuals. Asymptomatic colonisation with P jiroveci has recently been described in patients who are either minimally immunosuppressed or who have underlying lung disorders such as bronchiectasis. We sought to determine the prevalence of asymptomatic colonisation by P jiroveci in a cohort of adult patients undergoing diagnostic bronchoscopy.

METHODS

A prospective observational cohort study was performed in patients who required bronchoscopy and bronchoalveolar lavage (BAL) as part of their routine clinical assessment. All the samples underwent standard microbiological analysis and a Grocott methenamine silver stain was performed where clinically indicated to detect the presence of P jiroveci. Polymerase chain reaction for detection of P jiroveci specific DNA was also performed.

RESULTS

Ninety three consecutive BAL fluid samples were analysed, 17 (18%) of which contained P jiroveci DNA. Of the potential predictors examined, only glucocorticoid use was significantly associated with detectable P jiroveci DNA. Eighteen patients were receiving oral glucocorticoids (equivalent to >20 mg/day prednisolone) at the time of bronchoscopy, of whom eight (44%) had detectable P jiroveci DNA. In contrast, P jiroveci was detected in only nine of 75 patients (12%) who were not receiving glucocorticoids (difference between proportions 32%, 95% CI 8 to 57; p=0.004, two tailed Fisher's exact test).

CONCLUSIONS

P jiroveci colonisation, as determined by detection of P jiroveci DNA in BAL fluid, is common in HIV negative patients with primary respiratory disorders undergoing bronchoscopy and BAL. The higher prevalence in patients receiving corticosteroids suggests that oral glucocorticoid therapy is an independent risk factor for colonisation. In contrast, underlying lung cancer or COPD did not appear to be risk factors.

Genotypes at the internal transcribed spacers of the nuclear rRNA operon of Pneumocystis jiroveci in nonimmunosuppressed infants without severe pneumonia

The frequency of Pneumocystis jiroveci (human-derived Pneumocystis) in immunocompetent infants developing acute respiratory syndromes has recently been evaluated and has been shown to be close to 25%. Until now, there have been no data on the genomic characteristics of the fungus in these patients, while molecular typing of P. jiroveci organisms was mostly performed with samples from immunosuppressed patients with pneumocystosis (Pneumocystis carinii pneumonia [PCP]). The present report describes the genotypes of P. jiroveci organisms in 26 nonimmunosuppressed infants developing a mild Pneumocystis infection contemporaneously with an episode of bronchioloalveolitis. The typing was based on sequence analysis of internal transcribed spacers (ITSs) 1 and 2 of the rRNA operon, followed by the use of two typing scores. By use of the first score, 11 P. jiroveci ITS types were identified: 10 were previously reported in immunosuppressed patients with PCP, while 1 was newly described. By use of the second score, 13 types were identified, of which 2 were newly described. The most frequent type was identified as type B(1)a(3) (first score), which corresponds to type Eg (second score). Mixed infections were diagnosed in three infants. The occurrence of such diversity of P. jiroveci ITS types, an identical main type, and mixed infections has previously been reported in immunosuppressed patients with PCP. Thus, the P. jiroveci ITS genotypes detected in immunocompetent infants and immunosuppressed patients developing different forms of Pneumocystis infection share characteristics, suggesting that both groups of individuals make up a common human reservoir for the fungus. Finally, the frequency of P. jiroveci in nonimmunosuppressed infants with acute respiratory syndromes and the genotyping results provide evidence that this infant population is an important reservoir for the fungus.

Occurrence of Pneumocystis carinii in HIV-positive patients with suspected pulmonary tuberculosis in Ethiopia

OBJECTIVE

To investigate the prevalence of Pneumocystis carinii in consecutive HIV-positive patients with suspected pulmonary tuberculosis (PTB) attending a university hospital in Ethiopia.

METHODS

A PCR for P. carinii and an indirect immunoflorescence (IF) assay were performed on expectorated sputum samples from: 119 HIV-1-positive patients with negative smears and sputum cultures for Mycobacterium tuberculosis; 96 HIV-1-positive patients with culture-verified PTB; and 97 HIV-negative patients with negative mycobacterial cultures and 72 HIV-negative patients with culture-verified PTB, serving as controls. Outcome of PCR and IF were compared with the chest radiographic (CXR) and initial clinical diagnosis.

RESULTS

In the HIV+PTB- group, P. carinii was found in 10.9% by IF, 8.4% by single PCR (sPCR) and 30.3% by nested PCR (nPCR). In the HIV+PTB+ group, 3.1% were P. carinii positive by IF and sPCR and 13.5% by nPCR. All IF- and sPCR-positive samples were nPCR positive. In the HIV-PTB+ and HIV-PTB- groups, 4.2% and 3.1% were nPCR positive, respectively. Six out of eight HIV+PTB- patients with CXR suggesting P. carinii pneumonia (PCP) were IF and/or nPCR positive for P. carinii. In the IF-positive and nested PCR-positive HIV+PTB- patients more than one-third were interpreted as PTB by CXR whereas only one patient was diagnosed with clinical PCP.

CONCLUSIONS

P. carinii is prevalent in HIV-positive PTB suspects, suggesting that PCP may be an important, but not well recognized, differential diagnosis. Our findings have implications for treatment and primary prophylaxis for PCP in Ethiopia.

Pneumocystis jiroveci internal transcribed spacer types in patients colonized by the fungus and in patients with pneumocystosis from the same French geographic region

Pneumocystis jiroveci (human-derived Pneumocystis) infections can display a broad spectrum of clinical presentations, of which pulmonary colonization with the fungus may represent an important part, occurring frequently in patients with various underlying diseases and presenting alternative diagnoses of acute pneumocystosis (Pneumocystis carinii pneumonia [PCP]). There are few data concerning the P. jiroveci genotypes involved in pulmonary colonization, whereas several genotypes responsible for PCP in immunocompromised patients have been described. In this study, P. jiroveci genotypes have retrospectively been investigated and compared in 6 colonized patients and in 11 patients with PCP who were in the same hospital. Seventeen archival bronchoalveolar lavage samples were genotyped at internal-transcribed spacer 1 (ITS1) and ITS2 of the nuclear rRNA operon. Fourteen different genotypes were identified, of which 1 was found only in colonized patients, 10 were found only in patients with PCP, and 3 were found in both patient populations. Mixed infections were diagnosed in 2 of the 6 colonized patients and in 6 of the 11 patients with PCP. The results show that similar genotypes can be responsible for PCP as well as pulmonary colonization. There is a high diversity of genotypes in colonized patients and in patients with PCP. Mixed infections may occur in these two patient populations. These shared features of P. jiroveci ITS genotypes in colonized patients and patients with PCP suggest that human populations infected by P. jiroveci, whatever the clinical manifestation, may play a role as a common reservoir for the fungus.

Clinical significance of nested polymerase chain reaction and immunofluorescence for detection of Pneumocystis carinii pneumonia

OBJECTIVE

To study the clinical significance of a nested polymerase chain reaction (PCR) method compared to immunofluorescence (IF) for detection of Pneumocystis carinii.

METHODS

The medical records of 89 patients with 91 episodes of pneumonia were scrutinised retrospectively. The pneumonia episodes were divided into categories according to the likelihood that the patient had had clinical Pneumocystis carinii pneumonia (PCP). All respiratory tract samples from the 89 patients (34 broncho-alveolar lavage (BAL) and 57 sputa) were tested for Pneumocystis carinii by IF and nested PCR.

RESULTS

Fifteen episodes, as diagnosed by IF, were classified as true PCP (combination of the groups with definite and probable PCP; sensitivity 60%, specificity 97%). Among the P. carinii DNA-positive episodes, detected with nested PCR, 24 were classified as true PCP (combination of the groups with definite and probable PCP; sensitivity 96%, specificity 59%), since all IF-positive samples were nested PCR positive. Only one pneumonia episode classified as a probable PCP, was negative with both methods, as applied to a BAL sample.

CONCLUSIONS

IF applied to BAL or sputum seems to be the most specific method for diagnosis of clinical PCP. Additional clinical cases can be found by nested PCR, although this then gives a high risk of detecting subclinical colonisation of P. carinii.

Evaluation of diagnostic value and epidemiological implications of PCR for Pneumocystis carinii in different immunosuppressed and immunocompetent patient groups

To evaluate the value of single and nested PCRs for diagnosis of Pneumocystis carinii pneumonia (PCP) in a variety of respiratorily distressed patient groups, 574 respiratory samples from 334 patients (89 human immunodeficiency virus [HIV]-positive patients, 61 transplant recipients, 66 malignancy patients, 34 otherwise immunosuppressed patients, and 84 immunocompetent patients) were prospectively examined by microscopy and single and nested PCRs. The resulting data were correlated with clinical evidence of PCP. Microscopy and single PCR of bronchoalveolar lavage (BAL) specimens from HIV patients were 100% sensitive and specific in detecting PCP, whereas nested PCR, although being 100% sensitive, reached a specificity of only 97.5%. In the three non-HIV immunosuppressed patient groups, both single and nested PCR invariably produced lower positive predictive values than microscopy. Among immunocompetent patients, the positive predictive values of both PCRs were 0%. Therefore, the diagnostic values of the PCR methods tested do not seem to offer any additional advantage compared to that of conventional microscopy for these patient groups. However, nested PCR identified a significant percentage of clinically silent P. carinii colonizations in about 17 to 20% of immunocompetent and immunosuppressed non-HIV patients.

Pneumocystis carinii carriage in immunocompetent patients with primary pulmonary disorders as detected by single or nested PCR

Ninety-five bronchoalveolar lavage specimens from 63 immunocompetent adult patients with primary pulmonary disease were analyzed for Pneumocystis carinii colonization by primary and nested PCR. Twelve of 63 patients (19%) were PCR positive. None of them developed P. carinii pneumonia. These results suggest that P. carinii carriage may exist in immunocompetent patients with underlying pulmonary disease.

Pneumocystis carinii infection in non-AIDS patients

Infection with the opportunist fungus Pneumocystis carinii remains a significant cause of morbidity and mortality in non-HIV-infected individuals immunosuppressed by a wide range of malignancies, transplantation and inflammatory conditions. Glucocorticoid use appears to be an independent risk factor for the development of Pneumocystis carinii pneumonia. Transmission from infected to susceptible patients may occur, albeit infrequently. A diagnosis of Pneumocystis carinii pneumonia may be achieved in the majority of cases by DNA detection using polymerase chain reaction on oropharyngeal mouth washes.