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American Journal of Respiratory and... Dec 2023
Topics: Humans; Pneumonia, Pneumocystis; Pneumocystis carinii; Immunocompromised Host
PubMed: 37489929
DOI: 10.1164/rccm.202212-2195IM -
European Journal of Epidemiology May 1992Pneumocystis carinii is a widespread eukaryotic microorganism found in the lungs of healthy mammals, including humans. It is able to proliferate extensively in the... (Comparative Study)
Comparative Study Review
Pneumocystis carinii is a widespread eukaryotic microorganism found in the lungs of healthy mammals, including humans. It is able to proliferate extensively in the alveoli, becoming an important agent of severe pneumonitis in immunosuppressed hosts, especially in persons suffering from AIDS. The taxonomic position of P. carinii is uncertain. Typical cytoplasmic organelles of eukaryotic cells have been found and described in the parasite. Biochemical research is hindered by the lack of an efficient in vitro culture system. Results of comparative study of nucleic acid sequences suggest that Pneumocystis is a fungus. However, ultrastructural, biochemical and nucleic acid homology insights appear as clearly insufficient to class Pneumocystis. Pneumocystis infection might be acquired, as deep mycoses, from environmental sources through the respiratory tract. Thus, the hypothesis of an environmental stage of the parasite must be considered. Pneumocystis might be seen as a widespread pathogenic dimorphous fungus. As fungal agents, P. carinii is able to disseminate from the infected lung to other organs. However, deep mycoses and pneumocystosis induce different histopathological changes in the host. Furthermore, deep fungal infections, unlike pneumocystosis, cannot be transmitted from one infested host to another one. Beside these two aspects, pneumocystosis shares many features with deep mycoses. Research on the epidemiology of pneumocystosis is needed.
Topics: Animals; Humans; Mycoses; Pneumocystis; Pneumonia, Pneumocystis
PubMed: 1397210
DOI: 10.1007/BF00158583 -
Leukemia & Lymphoma Aug 2022
Topics: Humans; Immunocompromised Host; Incidence; Pneumocystis carinii; Pneumonia, Pneumocystis
PubMed: 35341452
DOI: 10.1080/10428194.2022.2056179 -
PLoS Pathogens Nov 2014
Review
Topics: Animals; Genome, Fungal; Humans; Pneumocystis carinii; Pneumonia, Pneumocystis
PubMed: 25375856
DOI: 10.1371/journal.ppat.1004425 -
Expert Review of Anti-infective Therapy Mar 2010A Commemorative Conference of Pneumocystis Discovery First Centenary was held in Brussels, Belgium, on 5-6 November 2009. A total of 16 keynote speakers from different...
A Commemorative Conference of Pneumocystis Discovery First Centenary was held in Brussels, Belgium, on 5-6 November 2009. A total of 16 keynote speakers from different countries attended the meeting. This conference has allowed the principal European and non-European groups who are working on Pneumocystis infection to gather together, in order to expose the most recent advances accomplished in the basic and translational scientific knowledge of Pneumocystis infection, and to discuss the trends of future research in this area.
Topics: Child; Child, Preschool; Humans; Pneumocystis; Pneumocystis Infections; Pneumonia, Pneumocystis; Research
PubMed: 20192679
DOI: 10.1586/eri.10.11 -
Medical Mycology Nov 2010Pneumocystis jirovecii is an atypical opportunistic fungus with lung tropism and worldwide distribution that causes pneumonia in immunosuppressed individuals. The...
Pneumocystis jirovecii is an atypical opportunistic fungus with lung tropism and worldwide distribution that causes pneumonia in immunosuppressed individuals. The development of sensitive molecular techniques has led to the recognition of a colonization or carrier state of P. jirovecii, in which low levels of the organism are detected in persons who do not have pneumonia. Pneumocystis colonization has been described in individuals with various lung diseases, and accumulating evidence suggests that it may be a relevant issue with potential clinical impact. Only a few published studies carried out in Europe have evaluated the prevalence of Pneumocystis colonization in patients with cystic fibrosis, reporting ranges from 1.3-21.6%. The evolution of P. jirovecii colonization in cystic fibrosis patients is largely unknown. In a longitudinal study, none of the colonized patients developed pneumonia during a 1-year follow-up. Since patients with cystic fibrosis could act as major reservoirs and sources of infection for susceptible individuals further research is thus warranted to assess the true scope of the problem and to design rational preventive strategies if necessary. Moreover, it's necessary to elucidate the role of P. jirovecii infection in the natural history of cystic fibrosis in order to improve the clinical management of this disease.
Topics: Carrier State; Cystic Fibrosis; Europe; Genotype; Humans; Pneumocystis carinii; Pneumonia, Pneumocystis; Prevalence
PubMed: 21067325
DOI: 10.3109/13693786.2010.505205 -
Lakartidningen Jan 1999Despite recent decrease in the incidence of Pneumocystis carinii pneumonia (PCP) among patients infected with HIV (human immunodeficiency virus), PCP remains a threat to... (Review)
Review
Despite recent decrease in the incidence of Pneumocystis carinii pneumonia (PCP) among patients infected with HIV (human immunodeficiency virus), PCP remains a threat to other categories of immunocompromised patients. The article provides an outline of recent, mainly molecular genetic, findings in P. carinii research, including its new classification as a primitive fungus, host specificity and verified de novo infection in HIV-infected subjects. As the pathogen still defies propagation in vitro, laboratory diagnosis is dependent on microscopic demonstration of the organism. Diagnostic specificity can be enhanced by generating specific PCR (polymerase chain reaction) products which can be sequenced for genotyping. Findings in animal studies and epidemiological observations (e.g., in outbreaks of PCP among immunocompromised hospital patients), suggest transmission of PCP infection to be airborne. Genetic methods have been used to study the mode of P. carinii transmission. Nucleic acids of the human form of P. carinii (P. carinii f. sp. hominis) have been detected in the air of hospital wards, indicating susceptible patients to be at risk. By contrast, findings obtained with the same methods in studies of person-to-person transmission of P. carinii among clustered cases of PCP in hospitals suggest infection to be environmentally acquired. Thus, many questions remain to be answered regarding the occurrence and transmission of P. carinii infection.
Topics: AIDS-Related Opportunistic Infections; Air Microbiology; Humans; Immunocompromised Host; Pneumocystis; Pneumonia, Pneumocystis; Polymerase Chain Reaction
PubMed: 10024821
DOI: No ID Found -
Mycopathologia May 2024Pneumocystis pneumonia is a serious lung infection caused by an original ubiquitous fungus with opportunistic behavior, referred to as Pneumocystis jirovecii. P....
Pneumocystis pneumonia is a serious lung infection caused by an original ubiquitous fungus with opportunistic behavior, referred to as Pneumocystis jirovecii. P. jirovecii is the second most common fungal agent among invasive fungal infections after Candida spp. Unfortunately, there is still an inability to culture P. jirovecii in vitro, and so a great impairment to improve knowledge on the pathogenesis of Pneumocystis pneumonia. In this context, animal models have a high value to address complex interplay between Pneumocystis and the components of the host immune system. Here, we propose a protocol for a murine model of Pneumocystis pneumonia. Animals become susceptible to Pneumocystis by acquiring an immunocompromised status induced by iterative administration of steroids within drinking water. Thereafter, the experimental infection is completed by an intranasal challenge with homogenates of mouse lungs containing Pneumocystis murina. The onset of clinical signs occurs within 5 weeks following the infectious challenge and immunosuppression can then be withdrawn. At termination, lungs and bronchoalveolar lavage (BAL) fluids from infected mice are analyzed for fungal load (qPCR) and immune response (flow cytometry and biochemical assays). The model is a useful tool in studies focusing on immune responses initiated after the establishment of Pneumocystis pneumonia.
Topics: Animals; Pneumonia, Pneumocystis; Disease Models, Animal; Bronchoalveolar Lavage Fluid; Lung; Mice; Pneumocystis; Colony Count, Microbial; Pneumocystis carinii; Immunocompromised Host
PubMed: 38709375
DOI: 10.1007/s11046-024-00846-1 -
International Journal For Parasitology Jan 1998Pneumocystis carinii pneumonia remains a prevalent opportunistic disease among immunocompromised individuals. Although aggressive prophylaxis has decreased the number of... (Review)
Review
Pneumocystis carinii pneumonia remains a prevalent opportunistic disease among immunocompromised individuals. Although aggressive prophylaxis has decreased the number of acute P. carinii pneumonia cases, many patients cannot tolerate the available drugs, and experience recurrence of the infection, which can be fatal. It is now generally agreed that the organism should be placed with the fungi, but the identification of extant fungal species representing its closest kins, remains debated. Most recent data indicate that P. carinii represents a diverse group of organisms. Since the lack of methods for the continuous subcultivation of this organism hampered P. carinii research, molecular cloning and nucleotide sequencing approaches led the way for understanding the biochemical nature of this pathogen. However, within the last 5 years, the development of improved protocols for isolating and purifying viable organisms from infected mammalian host lungs has enabled direct biochemical and metabolism studies on the organism. The protein moiety of the major high mol. wt surface antigen, represented by numerous isoforms, is encoded by different genes. These proteins are post-transcriptionally modified by carbohydrates and lipids. The organism has the shikimic acid pathway that leads to the formation of compounds which mammals cannot synthesise (e.g., folic acid), hence drugs that inhibit these pathways are effective against the pathogen. Ornithine decarboxylase has now been detected; rapid and complete depletion of polyamines occurs in response to difluoromethylornithine (DFMO). Instead of ergosterol (the major sterol of higher fungi), P. carinii synthesises distinct delta7, C-24-alkylated sterols. An unusual C32 sterol, pneumocysterol, has been identified in human-derived P. carinii. Another signature lipid discovered is cis-9,10-epoxy stearic acid. CoQ10, identified as the major ubiquinone homologue, is synthesised de novo by P. carinii. Atovaquone and other hydroxynaphthoquinone drugs with anti-P. carinii activity probably inhibit pathogen respiration as CoQ analogues. Unlike its effects on Plasmodium, atovaquone does not inhibit the P. carinii dihydroorotate dehydrogenase and pyrimidine metabolism.
Topics: Animals; Bacterial Proteins; Enzymes; Genes, Bacterial; Humans; Mammals; Pneumocystis; Pneumonia, Pneumocystis
PubMed: 9504336
DOI: 10.1016/s0020-7519(97)00179-3 -
Zhurnal Mikrobiologii, Epidemiologii I... 1994
Review
Topics: AIDS-Related Opportunistic Infections; Animals; HIV-1; Humans; Pneumocystis; Pneumonia, Pneumocystis
PubMed: 7992519
DOI: No ID Found