-
Medical Mycology Nov 2020Pneumocystis jirovecii can cause life-threatening pneumonia in immunocompromised patients. Traditional diagnostic testing has relied on staining and direct visualization... (Review)
Review
Pneumocystis jirovecii can cause life-threatening pneumonia in immunocompromised patients. Traditional diagnostic testing has relied on staining and direct visualization of the life-forms in bronchoalveolar lavage fluid. This method has proven insensitive, and invasive procedures may be needed to obtain adequate samples. Molecular methods of detection such as polymerase chain reaction (PCR), loop-mediated isothermal amplification (LAMP), and antibody-antigen assays have been developed in an effort to solve these problems. These techniques are very sensitive and have the potential to detect Pneumocystis life-forms in noninvasive samples such as sputum, oral washes, nasopharyngeal aspirates, and serum. This review evaluates 100 studies that compare use of various diagnostic tests for Pneumocystis jirovecii pneumonia (PCP) in patient samples. Novel diagnostic methods have been widely used in the research setting but have faced barriers to clinical implementation including: interpretation of low fungal burdens, standardization of techniques, integration into resource-poor settings, poor understanding of the impact of host factors, geographic variations in the organism, heterogeneity of studies, and limited clinician recognition of PCP. Addressing these barriers will require identification of phenotypes that progress to PCP and diagnostic cut-offs for colonization, generation of life-form specific markers, comparison of commercial PCR assays, investigation of cost-effective point of care options, evaluation of host factors such as HIV status that may impact diagnosis, and identification of markers of genetic diversity that may be useful in diagnostic panels. Performing high-quality studies and educating physicians will be crucial to improve the rates of diagnosis of PCP and ultimately to improve patient outcomes.
Topics: Humans; Immunoassay; Immunocompromised Host; Microbiological Techniques; Pneumocystis carinii; Pneumonia, Pneumocystis; Polymerase Chain Reaction; Sensitivity and Specificity; Specimen Handling; Staining and Labeling
PubMed: 32400869
DOI: 10.1093/mmy/myaa024 -
Cold Spring Harbor Perspectives in... Nov 2014Since its initial misidentification as a trypanosome some 100 years ago, Pneumocystis has remained recalcitrant to study. Although we have learned much, we still do not... (Review)
Review
Since its initial misidentification as a trypanosome some 100 years ago, Pneumocystis has remained recalcitrant to study. Although we have learned much, we still do not have definitive answers to such basic questions as, where is the reservoir of infection, how does Pneumocystis reproduce, what is the mechanism of infection, and are there true species of Pneumocystis? The goal of this review is to provide the reader the most up to date information available about the biology of Pneumocystis and the disease it produces.
Topics: Humans; Pneumocystis; Pneumocystis Infections; Pneumonia, Pneumocystis; Virulence Factors
PubMed: 25367973
DOI: 10.1101/cshperspect.a019828 -
International Journal of Medical... Oct 2002Pneumocystis organisms can cause pneumonia in mammals that lack a strong immune defense. The genus Pneumocystis contains many different organisms that can be... (Review)
Review
Pneumocystis organisms can cause pneumonia in mammals that lack a strong immune defense. The genus Pneumocystis contains many different organisms that can be distinguished by DNA sequence analysis. These different organisms are different species of yeast-like fungi that are most closely related to the ascomycete, Schizosaccharomyces pombe. Each species of Pneumocystis appears to be specific for the mammal in which it is found. The species that infects humans is Pneumocystis jiroveci. P. jiroveci has not been found in any other mammal and the species of Pneumocystis found in other mammals have not been seen in humans. Genetic variation among P. jiroveci samples is common, suggesting that there are many strains. Strain analysis shows that adults can be infected by more than one strain, and suggests that pneumonia can be the result of infection occurring proximal to the time of disease, rather than to reactivation of dormant organisms acquired in early childhood. Nevertheless, long-term colonisation may be occurring. A large fraction of normal children and animals show evidence of infection. A Pneumocystis species that grows in rats has been shown to possess a complex genetic system for surface antigen variation, a strategy employed by other microbes that dwell in immunocompetent hosts. These findings, together with strong host specificity, suggest that Pneumocystis species may be obligate parasites. The source of infection is not clear. Pneumocystis DNA is detectable in the air, but is scarce except in environments occupied by individuals with Pneumocystis pneumonia. In a few cases, there is direct evidence of person to person transmission. In general, however, patients and their contacts have been found to have different strains of P. jiroveci.
Topics: Animals; Ascomycota; DNA, Fungal; Genetic Variation; Humans; Pneumocystis; Pneumonia, Pneumocystis; Species Specificity
PubMed: 12452285
DOI: 10.1078/1438-4221-00222 -
Seminars in Respiratory and Critical... Dec 2011Pneumocystis (carinii) jiroveci pneumonia can occur in immunocompromised individuals, especially hematopoietic stem and solid organ transplant recipients and those... (Review)
Review
Pneumocystis (carinii) jiroveci pneumonia can occur in immunocompromised individuals, especially hematopoietic stem and solid organ transplant recipients and those receiving immunosuppressive agents, and is the most common opportunistic infection in persons with advanced human immunodeficiency virus (HIV) infection. The Pneumocystis genus was initially mistaken as a trypanosome and later as a protozoan. Genetic analysis identified the organism as a unicellular fungus. Pneumocystis jiroveci is the species responsible for human infections. A slow indolent time course with symptoms of pneumonia progressing over weeks to months is characteristic in HIV-infected patients. Fulminant respiratory failure associated with fever and dry cough is typical in non-HIV-infected patients. Definitive diagnosis relies on histopathological testing of sputum, induced or sampled by fiberoptic bronchoscopy with bronchoalveolar lavage. The first-line drug for treatment and prevention is trimethoprim-sulfamethoxazole.
Topics: Adrenal Cortex Hormones; Anti-Infective Agents; Chemoprevention; Humans; Immunocompromised Host; Pneumocystis carinii; Pneumonia, Pneumocystis
PubMed: 22167405
DOI: 10.1055/s-0031-1295725 -
Trends in Microbiology Dec 2020
Topics: Genome, Fungal; Humans; Lung; Pneumocystis Infections; Pneumocystis carinii; Pneumonia, Pneumocystis
PubMed: 33171104
DOI: 10.1016/j.tim.2020.03.006 -
PLoS Pathogens Sep 2020
Review
Topics: Animals; Humans; Lung; Pneumocystis; Pneumonia, Pneumocystis; Species Specificity
PubMed: 32913371
DOI: 10.1371/journal.ppat.1008824 -
International Journal of Environmental... Mar 2022Pneumocystis is an atypical fungus that resides in the pulmonary parenchyma of many mammals, including humans and dogs. Immunocompetent human hosts are usually...
Pneumocystis is an atypical fungus that resides in the pulmonary parenchyma of many mammals, including humans and dogs. Immunocompetent human hosts are usually asymptomatically colonised or show subtle clinical signs, but some immunocompromised people can develop florid life-threatening Pneumocystis pneumonia (PCP). Since much less is known concerning Pneumocystis in dogs, we posit the question: can Pneumocystis colonization be present in dogs with inflammatory airway or lung disease caused by other pathogens or disease processes? In this study, Pneumocystis DNA was detected in bronchoalveolar lavage fluid (BALF) of 22/255 dogs (9%) with respiratory distress and/or chronic cough. Although young dogs (<1 year-of-age) and pedigree breeds were more often Pneumocystis-qPCR positive than older dogs and crossbreds, adult dogs with other infectious conditions and/or a history of therapy-resistant pulmonary disease could also be qPCR-positive, including two patients with suppression of the immune system. Absence of pathognomonic clinical or radiographic signs render it impossible to convincingly discriminate between overt PCP versus other lung/airway disease processes colonised by P. canis. It is possible that colonisation with P. canis might play a certain role as a co-pathogen in some canine patients with lower respiratory disease.
Topics: Animals; Bronchoalveolar Lavage Fluid; Dogs; Humans; Lung; Mammals; Plant Breeding; Pneumocystis; Pneumonia, Pneumocystis
PubMed: 35328882
DOI: 10.3390/ijerph19063192 -
FEMS Microbiology Letters Aug 2004Pneumocystis is a parasitic fungus causing pneumonia in immunosuppressed mammals and S-adenosylmethionine a key intermediary metabolite for all cells. Other than a... (Review)
Review
Pneumocystis is a parasitic fungus causing pneumonia in immunosuppressed mammals and S-adenosylmethionine a key intermediary metabolite for all cells. Other than a species of Rickettsia bacteria and an aberrant strain of the protozoan Amoeba proteus, Pneumocystis is the only cell known unable to synthesize AdoMet; it must extract this key compound from its host. This was discovered using a culture system and confirmed by observing depletion of AdoMet in the plasma of infected animals. Depletion also occurs in patients with Pneumocystis pneumonia (PcP), a phenomenon suggested as a basis for a method for diagnosis and evaluation of response to therapy. Preliminary data indicate that deliberate reduction of host lung AdoMet by nicotine treatment is therapeutic in the rat model of Pneumocystis pneumonia.
Topics: Animals; Humans; Methionine Adenosyltransferase; Nicotine; Pneumocystis; Pneumonia, Pneumocystis; Rats; S-Adenosylmethionine
PubMed: 15321660
DOI: 10.1016/j.femsle.2004.06.039 -
Parasitology Research Oct 2015Pneumocystis pneumonia is an opportunistic disease caused by invasion of unicellular fungus Pneumocystis jirovecii. Initially, it was responsible for majority of... (Review)
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.
Topics: AIDS-Related Opportunistic Infections; Genotype; Humans; Immunocompromised Host; Pneumocystis carinii; Pneumonia, Pneumocystis
PubMed: 26281787
DOI: 10.1007/s00436-015-4678-6 -
British Medical Bulletin 2002Pneumocystis carinii is an atypical fungus that causes pneumonia in immunocompromised individuals. P. carinii comprises a heterogeneous group of organisms that have been... (Review)
Review
Pneumocystis carinii is an atypical fungus that causes pneumonia in immunocompromised individuals. P. carinii comprises a heterogeneous group of organisms that have been isolated from a wide range of mammalian host species. P. carinii infection is host species specific, the P. carinii organisms that infect humans have only been found in humans. This review discusses the application of molecular techniques to the study of the biology and epidemiology of P. carinii infection. It addresses the use of DNA amplification for the detection and diagnosis of P. carinii pneumonia. Studies investigating the reservoir of infectious P. carinii organisms, the routes of transmission of the infection, and the emergence of drug resistant strains of P. carinii are also discussed.
Topics: Child; DNA, Fungal; Drug Resistance, Fungal; Genome, Fungal; Humans; Immunosuppression Therapy; Pneumocystis; Pneumonia, Pneumocystis; Polymerase Chain Reaction
PubMed: 11997305
DOI: 10.1093/bmb/61.1.175