P. Carinii Pneumonia Research Articles

Topomer CoMFA 3D-QSAR and Docking Studies of Pyrimidine Inhibitors of Pneumocystis Carinii Dihydrofolate Reductase

P. carinii dihydrofolate reductase (PcDHFR) inhibitors are used for the treatment of P. carinii pneumonia (PCP) in humans with acquired immunodeficiency syndrome (AIDS). Translocation comparative molecular field vector analysis (Topomer CoMFA) 3D-QSAR and molecular docking were applied for a series of pyrimidine derivatives. 64 Pyrimidine derivatives were analyzed and the relationship between the structures and bioactivities was explored. Topomer CoMFA was used to build 3D-QSAR model, the results show that cross-validation q2 = 0.721, SDCV = 0.52, the non-crossvalidated r2 = 0.922, SD = 0.28, and the correlation coefficient of external validation Q2 ext = 0.934, this indicated that model generated form Topomer CoMFA was reasonable, and had good prediction ability. The mechanism of action of drug was studied by molecular docking. It showed that the pyrimidine compounds and GLU32, ILE123, LYS37 sites of PcDHFR have interactions. These results have provided an insight for the design of new potent inhibitors of PcDHFR. Keywords: 3D-QSAR, dihydrofolate reductase, pyrimidine derivatives, topomer CoMFA, molecular docking.

CoMFA/CoMSIA 3D-QSAR of pyrimidine inhibitors of Pneumocystis carinii dihydrofolate reductase

Pneumocystis carinii is typically a non-pathogenic fungus found in the respiratory tract of healthy humans. However, it may cause P. carinii pneumonia (PCP) in people with immune deficiency, affecting mainly premature babies, cancer patients and transplant recipients, and people with acquired immunodeficiency syndrome (AIDS). In the latter group, PCP occurs in approximately 80% of patients, a major cause of death. Currently, there are many available therapies to treat PCP patients, including P. carinii dihydrofolate reductase (PcDHFR) inhibitors, such as trimetrexate (TMX), piritrexim (PTX), trimethoprim (TMP), and pyrimethamine (PMT). Nevertheless, the high percentage of adverse side effects and the limited therapeutic success of the current drug therapy justify the search for new drugs rationally planned against PCP. This work focuses on the study of pyrimidine inhibitors of PcDHFR, using both CoMFA and CoMSIA 3D-QSAR methods.

Pneumocystis jiroveci Pneumonia in Patients with Non-Hodgkin's Lymphoma Receiving Chemotherapy Containing Rituximab

Rituximab enhances treatment efficacy of B-lineage lymphoma by targeting CD20 + B-cells. Such target therapies may compromise the immune system and render patients susceptible to opportunistic infections. We report 2 cases of lymphoma complicated with Pneumocystis jiroveci (previously known as P. carinii) pneumonia (PCP) while being treated with rituximab-containing chemotherapy regimens. In both cases, PCP developed during the neutropenic period. With timely diagnosis and proper management, both were treated successfully. We searched the literature and found that such opportunistic infection occurred only infrequently in lymphoma patients, and it has not been reported in the large-scale clinical trials of rituximab. Such cases demonstrate the importance of taking PCP into diagnostic consideration in lymphoma patients receiving similar therapies.

Perioral Numbness Associated with Intravenous Pentamidine Administration

To report a case of perioral numbness associated with intravenous pentamidine. A 56-year-old female with acute myelogenous leukemia in remission developed Pneumocystis carinii infection. Treatment was initiated with trimethoprim/sulfamethoxazole (TMP/SMX), but the patient subsequently developed a rash on day 10 of treatment. TMP/SMX was discontinued and intravenous pentamidine was started in order to complete a 21 day treatment course for P. carinii pneumonia (PCP). However, on day 3 of pentamidine treatment, the patient reported perioral numbness during the infusion. The numbness disappeared soon after completion of the infusion but recurred with all subsequent pentamidine infusions. Paresthesias in general and facial area numbness in particular have been reported with pentamidine administration. While it is possible such adverse events may be a result of pentamidine's effect on serum electrolytes and glucose, especially hypocalcemia and hypoglycemia, these laboratory values were not grossly affected by pentamidine in our patient. The Naranjo probability scale revealed a probable adverse reaction of perioral numbness associated with intravenous pentamidine. Pentamidine is considered an alternative agent to TMP/SMX in the treatment of PCP. Although they do not commonly occur, paresthesias have been reported with pentamidine therapy. Healthcare practitioners should be aware of this type of event in association with pentamidine administration, especially as it may not be associated with overt serum glucose or electrolyte disturbances.

Pneumocystis carinii pneumonia in a rheumatoid arthritis patient treated with adalimumab

Patients with rheumatoid arthritis (RA) have an increased risk of infection as a result of alterations in immune regulation, debility, and comorbid illnesses. TNF-alpha is of central importance in the pathophysiological responses to infection and inflammation, and plays a crucial role in host defence. Pneumocystis carinii is an opportunistic pathogen that commonly affects individuals with inadequate T-cell mediated immune response. Patients with acquired immune deficiency, as well as those receiving immunosuppressive drugs for various conditions have an increased risk of P. carinii pneumonia (PCP). We report the development of PCP in a woman with RA shortly after the initiation of anti-TNF-alpha treatment with adalimumab.

Detection of Pneumocystis carinii by DNA amplification in patients with connective tissue diseases: re-evaluation of clinical features of P. carinii pneumonia in rheumatic diseases

We evaluated the polymerase chain reaction (PCR) detection of Pneumocystis carinii DNA in induced sputum of patients with connective tissue diseases and assessed the clinical features of patients positive for P. carinii. Sputum was induced by nebulization in 29 in-patients with various connective tissue diseases who presented with symptoms suggestive of P. carinii pneumonia (PCP), and was examined by PCR. Detection of P. carinii DNA by PCR was significantly more sensitive than cytology; 54.5% patients were positive by PCR and only 4.5% by cytology. The prevalence of PCP was higher than previously considered and was especially high in patients receiving > 30 mg/day prednisolone with or without other immunosuppressants. P. carinii-positive patients had significant lymphocytopenia and a low serum IgG level compared with P. carinii-negative patients. P. carinii disappeared within 7-10 days after therapy with trimethoprim/sulfamethoxazole. We propose that the use of PCR for detection of P. carinii using induced sputum is a useful and non-invasive method that has high sensitivity and specificity for the early diagnosis of PCP.

Experimental Pneumocystis carinii pneumonia in simian immunodeficiency virus-infected rhesus macaques.

To establish experimental Pneumocystis carinii infection in simian immunodeficiency virus (SIV)-infected macaques as a model of acquired immunodeficiency syndrome (AIDS)-associated P. carinii pneumonia (PCP), SIV-infected macaques were inoculated intrabronchially with macaque-derived P. carinii, and P. carinii-specific polymerase chain reaction (PCR) and flow cytometric analysis of bronchoalveolar lavage fluid were done biweekly for up to 44 weeks after inoculation. All inoculated animals had a P. carinii-specific PCR product after infection. CD8(+) T cells in lung lavage samples from SIV- and P. carinii-coinfected animals increased to >90% of total CD3(+) cells, a pattern associated with naturally acquired P. carinii infection. Progression of disease also was correlated with increased neutrophil infiltration to the lungs. The animals had a protracted period of asymptomatic colonization with P. carinii before progression to PCP. The development of a model of PCP in SIV-infected rhesus macaques provides the means to study AIDS-associated PCP.

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

To investigate the prevalence of Pneumocystis carinii in consecutive HIV-positive patients with suspected pulmonary tuberculosis (PTB) attending a university hospital in Ethiopia. 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. 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. 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 carinii carriage in immunocompromised patients with and without human immunodeficiency virus infection.

Eighty-one bronchoalveolar lavage (BAL) specimens obtained from 26 HIV-infected, 45 non-HIV immunosuppressed and 10 immunocompetent patients with primary pulmonary diseases were analysed for the presence of Pneumocystis carinii by staining and by P. carinii 5S rDNA determined by PCR. P. carinii was observed by staining of BAL specimens from HIV-infected patients significantly more frequently than those from immunocompromised hosts without HIV infection (57.7% versus 20.0%, respectively). P. carinii 5S rDNA was detected by PCR assay in seven (26.9%) HIV-infected individuals, which was significantly more frequent than for four (8.9%) immunosuppressed patients without HIV infection, for whom staining was negative. None of these patients developed P. carinii pneumonia (PCP) within the follow-up period. BAL specimens from 10 immunocompetent patients with pulmonary disorders were negative for PCP by both staining and PCR assay.

Dihydrofolate reductase gene polymorphisms in Pneumocystis carinii f. sp. hominis in Japan.

This study examined polymorphisms in the dihydrofolate reductase (DHFR) gene of Pneumocystis carinii isolates from 27 patients with P. carinii pneumonia (PCP) in Japan. Four substitution sites with two synonymous and two non-synonymous changes were found. Two synonymous substitutions at nucleotide positions 540 and 312 were identified in one and 13 patients, respectively. Two amino acid substitutions (Ala67Val, Cysl66Tyr) were found in two different patients. No linkage of amino acid substitutions in DHFR to those in dihydropteroate synthase was observed. The two patients whose isolates showed non-synonymous DHFR mutations were not exposed to DHFR inhibitors before they developed PCP and were treated successfully with co-trimoxazole.

Identification of Pneumocystis carinii DNA in oropharyngeal mouth washes from AIDS children dying of respiratory illnesses.

Polymerase chain reaction (PCR) using Pneumocystis carinii-specific primers pAZ 102-H(5'-GTGTACGTTGCAAAGTACTC-3') and pAZ 102-E(5'-GATGGCTGTTTCCAAGCCCA-3') was performed on oropharyngeal washes obtained at autopsy from 22 AIDS children with histologically confirmed P. carinii pneumonia (PCP), and 48 control AIDS children who died from other infections. Fifteen of 22 (68%) PCP samples and none of 48 (0%) control samples had detectable P. carinii DNA (sensitivity 68%; specificity 100%; positive predictive value 100%; negative predictive value 87%). This method requires further validation in clinical practice.

Pneumocystis Carinii Infections

Pneumocystis carinii is a common pathogen among immunocompromised patients. The organism was originally classified as a protozoan until recent studies revealed more characteristics of a fungus. P. carinii is difficult to study because of the absence of an in vitro culture system. Trimethoprim-sulfamethaxozole is considered the drug of choice for P. carinii in adults and adolescents, including pregnant patients. P. carinii pneumonia (PCP) remains a major cause of morbidity and mortality in patients with human immunodeficiency virus infection. Even with the use of prophylaxis against P. carinii, PCP causes more deaths among patients with AIDS than does any other infectious disease process in the United States.

Mutations in dihydropteroate synthase gene of Pneumocystis carinii in HIV patients with Pneumocystis carinii pneumonia

The purpose of this study was to determine whether dihydropteroate synthase gene (DHPS) mutations were associated with the failure of sulpha/sulphone drugs used as prophylaxis agents in HIV infected patients. Results suggested that DHPS mutations were significantly associated with failure of anti- Pneumocystis carinii sulphone prophylaxis ( P=0.031). An increasing number of mutant P. carinii strains have been isolated from patients no longer having prophylaxis. There was no statistically significant difference in severity or outcome of the pneumonia caused by wild-type or mutant DHPS. Moreover, two of the three patients with mutant P. carinii pneumonia (PCP) were successfully treated with sulpha drugs. We think that P. carinii drug-resistance could be an emerging problem for immunocompromised patients including those with HIV infection.

Prophylaxis failure is associated with a specific Pneumocystis carinii genotype.

To investigate the possible association between Pneumocystis carinii types and various clinical and demographic parameters, we used molecular typing to analyze 93 bronchoalveolar lavage specimens from patients with P. carinii pneumonia (PCP). Multivariate regression analysis revealed an association between being infected with a specific P. carinii genotype and receiving anti-PCP prophylaxis (odds ratio, 4.4; 95% confidence interval, 1.0-18.6; P=.05), although no association with a specific drug was detected.

Plasminogen activator production in a rat model of Pneumocystis carinii pneumonia.

Several studies have indicated that the serine protease urokinase-plasminogen-activator (uPA) is an important factor in host defense against pulmonary pathogens. To gain a better insight into the role of uPA in Pneumocystis carinii (P. carinii) pneumonia (PCP), we evaluated PA production in alveolar macrophages (AMs) obtained from rats with steroid-induced PCP. Treatment with cortisone acetate favored PCP in 91% of rats. In the bronchoalveolar lavage (BAL) samples of immunosuppressed rats both with and without PCP, we observed a decrease in uPA activity as well as a decrease in cell number. Urokinase-PA production by AMs was reduced in rats treated with cortisone alone. However, an increase in cell-associated uPA was observed in rats with PCP. This increase appears to be produced in response to P carinii infection. In fact, when AMs obtained from untreated healthy or immunosuppressed uninfected rats were challenged with P carinii, a significant increase in PA activity in cell lysates was observed, though a lower response was obtained in cortisone-treated animals. Our results suggest that healthy AMs respond to the presence of P carinii with an increase in uPA production and that this response in immunodepressed rat-AMs is partially impaired.

Pneumocystis carinii pneumonia in patients being registered for smear-negative pulmonary tuberculosis in Malawi

The National TB Control Programme of Malawi registers and treats large numbers of patients with chronic cough for smear-negative pulmonary tuberculosis (PTB). Smear-negative PTB is diagnosed according to clinical and radiographic criteria, as mycobacterial cultures are not routinely available. In an area of high HIV seroprevalence there is a concern that other opportunistic infections apart from TB, such as Pneumocystis carinii, may be missed owing to lack of diagnostic facilities. The aims of this study were to investigate (i) the extent of P. carinii pneumonia (PCP) in patients about to be registered for smear-negative PTB; (ii) whether there were any clinical or radiological features that could help identify PCP in the absence of more detailed investigations; and (iii) the treatment outcome of PCP patients. A cohort of 352 patients who were about to be started on treatment for smear-negative PTB were investigated further in 1997–1999 by clinical assessment, HIV testing and bronchoscopy. HIV sero-prevalence was 89% ( 278 313 ). A total of 186 patients underwent bronchoscopy and bronchoalveolar lavage, and PCP was diagnosed by indirect immunofluorescence or polymerase chain reaction in 17 (9%) of this subgroup. Dyspnoea was significantly more common in PCP cases compared to non-PCP cases (RR 1·35; 95% CI 1·24–1·48; P = 0·008), but discrimination between the groups was difficult using clinical criteria alone. The outcome of PCP cases was poor despite management with high-dose co-trimoxazole and secondary co-trimoxazole prophylaxis, with a median survival of 4 months (25–75% range: 2–12 months).

Pneumocystis cariniiCytochrome b Mutations Are Associated with Atovaquone Exposure in Patients with AIDS

This retrospective cohort study was conducted to determine whether Pneumocystis carinii cytochrome b gene mutations in patients with AIDS and P. carinii pneumonia (PCP) are associated with atovaquone exposure. Portions of the P. carinii cytochrome b genes that were obtained from 60 patients with AIDS and PCP from 6 medical centers between 1995 and 1999 were amplified and sequenced by using polymerase chain reaction. Fifteen patients with previous atovaquone prophylaxis or treatment exposure were matched with 45 patients with no atovaquone exposure. Cytochrome b coenzyme Q binding site mutations were observed in 33% of isolates from patients exposed to atovaquone, compared with 6% from those who were not (P=.018). There was no difference in survival 1 month after treatment between patients with or without cytochrome b mutations (P=.14). Thus, cytochrome b mutations are significantly more common in patients with AIDS and PCP with atovaquone exposure, but the clinical significance of these mutations remains unknown.

Unsuspected Pneumocystis cariniipneumonia at presentation of severe primary immunodeficiency

BACKGROUNDPneumocystis carinii is an important pathogen in immunodeficiency but may be an unrecognised cause of respiratory compromise.OBJECTIVESTo ascertain the incidence of P cariniipneumonia (PCP) at presentation of severe combined immunodeficiency...

Pulmonary colonization with Pneumocystis carinii in human immunodeficiency virus-negative patients: assessing risk with blood CD4+ T cell counts.

Use of PCR analysis has led to detection of low numbers of Pneumocystis carinii organisms, which were undetectable by microscopy, in bronchoalveolar lavage (BAL) fluid specimens from immunosuppressed patients who showed no evidence of acute P. carinii pneumonia (PCP) (1). These low levels of par- asites were usually considered to reflect pulmonary coloniza- tion, but their significance was a subject of controversy. Cases of colonization were described mainly in patients positive for HIV who had blood CD4 1 T cell counts of /L (2). 6 ! 400 3 10 There were little data concerning HIV-negative patients (3). This study investigates the presence of P. carinii DNA in BAL fluid specimens from HIV-negative patients with no evidence of PCP and examines the link between colonization and decreases in blood CD4 1 T cell counts in this patient population.

Oropharyngeal samples for genotyping and monitoring response to treatment in AIDS patients with Pneumocystis carinii pneumonia.

A nested PCR, amplifying a portion of the gene encoding the mitochondrial large subunit ribosomal RNA (mt LSU rRNA) of Pneumocystis carinii sp. f. hominis was applied to oropharyngeal samples obtained on repeated occasions from 12 HIV-infected patients with P. carinii pneumonia (PCP) to monitor response to anti-P. carinii treatment. Genotyping of P. carinii sp. f. hominis was also performed on paired samples of oropharyngeal and broncho-alveolar lavage samples before the start of treatment, and on oropharyngeal samples during the course of treatment, by analysis of sequence variation at the internal transcribed spacer (ITS) regions of the nuclear rRNA operon. When a simple dilutional method was used, a reduction in the amount of amplification product was observed in samples from all patients during the course of treatment. In eight of the 12 patients, a single ITS sequence type was found in the oropharyngeal samples and also in the paired broncho-alveolar lavage sample. A mixed infection was identified in the samples from three patients. In eight patients, the ITS sequence types identified in the oropharyngeal sample were the same as in the broncho-alveolar lavage sample. Nested PCR amplifying the mt LSU rRNA on oropharyngeal samples provides a non-invasive method of monitoring response to treatment of PCP. ITS sequence typing of P. carinii sp. f. hominis from oropharyngeal samples appears to be a reliable alternative to broncho-alveolar lavage samples and provides a non-invasive tool for further epidemiological studies.