Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0019693 (HIV)
 170,526 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Pneumocystis carinii (PC) is an ubiquitous pathogen phylogenetically considered a fungus. In individuals with T-cell deficiency, PC produces typically an interstitial pneumonia. The primary infection is, perhaps, transmitted airborne, and is acquired during early infancy. PC was a rare cause of disease until the advent of AIDS. In susceptible patients infected with HIV it remains a major cause of morbidity and mortality despite appropriate prophylaxis and treatment. Mutations in the gene that encodes the enzyme dihydropteroate synthase are seemingly accountable for the failure of prophylaxis in some individuals. The incidence of new cases of PC pneumonia (PCP) in patients with infection with HIV has dropped substantially since the advent of highly active antiretroviral therapy (HAART). Ongoing trials are designed to study the effect of withdrawing prophylaxis for PCP in patients whose T-cell count has risen over 200/mm3 in response to HAART.
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PMID:[Pneumocystis carinii pneumonia in AIDS. New concepts for an old problem]. 1041 1

To determine factors associated with mutations in the Pneumocystis carinii dihydropteroate synthase (DHPS) gene, a prospective study of human immunodeficiency virus (HIV)-infected patients with confirmed P. carinii pneumonia was conducted in Atlanta, Seattle, and San Francisco. Clinical information was obtained from patient interview and chart abstraction. DHPS genotype was determined from DNA sequencing. Overall, 76 (68.5%) of 111 patients had a mutant DHPS genotype, including 22 (81.5%) of 27 patients from San Francisco. In multivariate analysis, sulfa or sulfone prophylaxis and study site were independent predictors of a mutant genotype. Fourteen (53.8%) of 26 patients who were newly diagnosed with HIV infection and had never taken prophylaxis had a mutant genotype. The significance of geographic location as a risk factor for mutant genotype and the high proportion of mutant genotypes among persons never prescribed prophylaxis, including those newly diagnosed with HIV infection, provide indirect evidence that these mutations are transmitted from person to person either directly or through a common environmental source.
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PMID:Sulfa or sulfone prophylaxis and geographic region predict mutations in the Pneumocystis carinii dihydropteroate synthase gene. 1097 17

Sulpha agents, which act by inhibiting the enzyme dihydropteroate synthase (DHPS), are used widely for the treatment and prophylaxis of Pneumocystis carinii pneumonia (PCP). Recently, we have shown that mutations in the dihydropteroate synthase (DHPS) gene of Pneumocystis carinii f.sp hominis are associated with failure of sulpha prophylaxis and increased mortality in HIV-1 positive patients with PCP, suggesting that DHPS mutations may cause sulpha resistance. To facilitate detection of DHPS mutations we developed a restriction fragment length polymorphism (RFLP) assay, detecting mutations at codon 55 and 57 of the P. carinii DHPS gene. The RFLP-assay was compared with direct DNA sequencing on 27 PCP isolates from HIV-1 positive patients with a mixture of wildtype and mutant DHPS types. In all samples the RFLP-assay correctly identified wildtype or DHPS mutation at codon 55 or 57. Combined with DNA extraction by a Chelex-based method, this method can be performed within 1 d and allows a fast, cost-efficient and reliable method of detection of DHPS mutations in P. carinii.
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PMID:Rapid detection of dihydropteroate polymorphism in AIDS-related Pneumocystis carinii pneumonia by restriction fragment length polymorphism. 1144 Feb 35

Pneumonia is the leading HIV-associated infection. It may occur at an early stage of HIV-infection. The spectrum of microorganisms includes bacteria, mainly Streptococcus pneumoniae, Staphylococcus aureus, Haemophilus influenzae and Mycobacterium tuberculosis. In addition, fungi such as Pneumocystis carinii, Cryptococcus neoformans and Histoplasma capsulatum are common HIV-associated pathogens. The diagnostic work-up depends on the epidemiology (travel history) and the immune status (CD4-lymphocytes). Imaging techniques are always required, and the microbiological analysis of expectorations should be performed. In patients with < 200/microliter CD4-lymphocytes, a bronchoalveolar lavage is generally required. If tuberculosis is suspected, a CT-scan and a transbronchial biopsy should be performed, irrespective of the CD4-lymphocyte counts. During treatment of Pneumocystis-carinii-pneumonia, the possibility of sulpha resistance (i.e. mutations in dihydropteroate synthase) should be considered. The primary and secondary prophylaxis against opportunistic pathogens can be discontinued in patients with effective antiretroviral therapy, as soon as CD4-lymphocytes persistently (> 3 months) remain above threshold levels.
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PMID:[Pneumonia in patients with HIV infection]. 1169 94

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.
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PMID:Mutations in dihydropteroate synthase gene of Pneumocystis carinii in HIV patients with Pneumocystis carinii pneumonia. 1173 42

Pneumocystis carinii pneumonia (PCP) is still the commonest AIDS-defining condition in the UK, although absolute numbers have fallen since 1990 with the advent of prophylaxis and highly active antiretroviral therapy (HAART). Further decreases in its incidence are unlikely unless efforts are made to reduce late first presentations of HIV, improve retention of patients in care and improve adherence to P. carinii prophylaxis. The widespread development of key mutations in the P. carinii dihydropteroate synthase gene in the 1990's suggests that the organism is evolving under positive evolutionary pressure, possibly mediated by widespread use of co-trimoxazole and dapsone prophylaxis. It is not clear whether these mutants lead to treatment failure with co-trimoxazole, since most episodes are treated successfully and failure of prophylaxis is rare. Molecular diagnosis of PCP is restricted to research use, due to difficulties with sensitivity, specificity and turn-around times. Patients are infected with multiple P. carinii subtypes and re-infection from an environmental source is probably more important than re-activation of an existing infection. Person-to-person transmission does not appear to be a major source of infection in HIV-infected patients. Recent reports have highlighted the potential complications of initiating HAART during treatment of PCP.
J HIV Ther 2002 Feb
PMID:Pneumocystis carinii: where are we now? 1195 98

To investigate the possible association between different prophylactic sulfa drugs and the genotype of the Pneumocystis jiroveci dihydropteroate synthase (DHPS) gene, we examined DHPS polymorphisms in clinical specimens from 158 immunosuppressed patients (38 HIV-negative and 120 HIV-positive), using polymerase chain reaction-single-strand conformation polymorphism. Fifty-seven (36.1%) of 158 patients were infected with a mutant DHPS genotype. All patients who developed P. jiroveci pneumonia (PcP) while receiving pyrimethamine/sulfadoxine (PM/SD) prophylaxis (n=14) had a strain harboring DHPS with an amino acid change at position 57 (Pro-->Ser). This mutation was only present in 20 (14%) of 144 patients not receiving prophylaxis (P<.001). Hospitalization in a specific hospital was an independent risk factor for having P. jiroveci harboring the same DHPS mutation, which indirectly supports that interhuman transmission may affect the dissemination of the mutant strains.
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PMID:Association between a specific Pneumocystis jiroveci dihydropteroate synthase mutation and failure of pyrimethamine/sulfadoxine prophylaxis in human immunodeficiency virus-positive and -negative patients. 1451 22

Pneumocystis pneumonia (PCP) remains a major cause of illness and death in HIV-infected persons. Sulfa drugs, trimethoprim-sulfamethoxazole (TMP-SMX) and dapsone are mainstays of PCP treatment and prophylaxis. While prophylaxis has reduced the incidence of PCP, its use has raised concerns about development of resistant organisms. The inability to culture human Pneumocystis, Pneumocystis jirovecii, in a standardized culture system prevents routine susceptibility testing and detection of drug resistance. In other microorganisms, sulfa drug resistance has resulted from specific point mutations in the dihydropteroate synthase (DHPS) gene. Similar mutations have been observed in P. jirovecii. Studies have consistently demonstrated a significant association between the use of sulfa drugs for PCP prophylaxis and DHPS gene mutations. Whether these mutations confer resistance to TMP-SMX or dapsone plus trimethoprim for PCP treatment remains unclear. We review studies of DHPS mutations in P. jirovecii and summarize the evidence for resistance to sulfamethoxazole and dapsone.
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PMID:Dihydropteroate synthase gene mutations in Pneumocystis and sulfa resistance. 1550 56

The detection of Pneumocystis DNA in clinical specimens by using PCR assays is leading to important advances in Pneumocystis pneumonia (PcP) clinical diagnosis, therapy and epidemiology. Highly sensitive and specific PCR tools improved the clinical diagnosis of PcP allowing an accurate, early diagnosis of Pneumocystis infection, which should lead to a decreased duration from onset of symptoms to treatment, a period with recognized impact on prognosis. This aspect has marked importance in HIV-negative immunocompromised patients, who develop often PcP with lower parasite rates than AIDS patients. The specific amplification of selected polymorphous sequences of Pneumocystis jirovecii genome, especially of internal transcribed spacer regions of the nuclear rRNA operon, has led to the identification of specific parasite genotypes which might be associated with PcP severity. Moreover, multi-locus genotyping revealed to be a useful tool to explore person-to-person transmission. Furthermore, PCR was recently used for detecting P. jirovecii dihydropteroate synthase gene mutations, which are apparently associated with sulfa drug resistance. PCR assays detected Pneumocystis-DNA in bronchoalveolar lavage fluid or biopsy specimens, but also in oropharyngeal washings obtained by rinsing of the mouth. This non-invasive procedure may reach 90%-sensitivity and has been used for monitoring the response to treatment in AIDS patients and for typing Pneumocystis isolates.
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PMID:Molecular diagnosis of Pneumocystis pneumonia. 1606 60

In the present study, in order to improve the detection of Pneumocystis jirovecii dihydropteroate synthase (DHPS) mutations in pulmonary specimens of HIV-infected patients with P. jirovecii pneumonia, we evaluated a microfiltration procedure for the removal of human cell contamination and a nested-PCR method, for amplification in specimens with low parasite load. In the studied population, PCR amplification of the DHPS gene was more successful in unfiltered than in filtered specimens, with both touchdown-PCR and nested-PCR procedures (p<0.05 and p<0.001, respectively), but the amount of host DNA in the samples analysed seems to be inversely related with the successful PCR parasite detection. Amplification of P. jirovecii DHPS gene with nested-PCR was achieved in 77.5% of the specimens studied, demonstrating that this is a useful method for the identification of mutations in pulmonary specimens, including samples with low parasite loads, and will facilitate the evaluation of the relationship between the P. jirovecii DHPS polymorphisms and clinical resistance to sulfa drugs.
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PMID:Detection of Pneumocystis jirovecii dihydropteroate synthase polymorphisms in patients with Pneumocystis pneumonia. 1619 98


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