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Antimicrobial Agents and Chemotherapy Oct 2019
Topics: Caspofungin; Catalytic Domain; Echinocandins; Glucosyltransferases; Humans; Mutagenesis, Site-Directed; Pneumocystis carinii; Pneumonia, Pneumocystis
PubMed: 31548210
DOI: 10.1128/AAC.01296-19 -
PLoS Pathogens 2012
Review
Topics: Animals; Humans; Pneumocystis; Pneumonia, Pneumocystis; Rats
PubMed: 23209406
DOI: 10.1371/journal.ppat.1003025 -
The Journal of Eukaryotic Microbiology 2013I am honored to receive the second Lifetime Achievement Award by International Workshops on Opportunistic Protists and to give this lecture. My research involves... (Review)
Review
I am honored to receive the second Lifetime Achievement Award by International Workshops on Opportunistic Protists and to give this lecture. My research involves Pneumocystis, an opportunistic pulmonary fungus that is a major cause of pneumonia ("PcP") in the immunocompromised host. I decided to focus on Pneumocystis ecology here because it has not attracted much interest. Pneumocystis infection is acquired by inhalation, and the cyst stage appears to be the infective form. Several fungal lung infections, such as coccidiomycosis, are not communicable, but occur by inhaling < 5 μm spores from environmental sources (buildings, parks), and can be affected by environmental factors. PcP risk factors include environmental constituents (temperature, humidity, SO2 , CO) and outdoor activities (camping). Clusters of PcP have occurred, but no environmental source has been found. Pneumocystis is communicable and outbreaks of PcP, especially in renal transplant patients, are an ongoing problem. Recent evidence suggests that most viable Pneumocystis organisms detected in the air are confined to a patient's room. Further efforts are needed to define the risk of Pneumocystis transmission in health care facilities; to develop more robust preventive measures; and to characterize the effects of climatological and air pollutant factors on Pneumocystis transmission in animal models similar to those used for respiratory viruses.
Topics: Disease Outbreaks; Ecology; Humans; Immunocompromised Host; Inhalation Exposure; Pneumocystis; Pneumonia, Pneumocystis; Risk Factors
PubMed: 24001365
DOI: 10.1111/jeu.12072 -
Journal of Medical Case Reports Feb 2024Pneumocystis jirovecii (PJP) pneumonia is a serious life-threatening condition in immunocompromised individuals and is often associated with human immunodeficiency virus...
INTRODUCTION AND IMPORTANCE
Pneumocystis jirovecii (PJP) pneumonia is a serious life-threatening condition in immunocompromised individuals and is often associated with human immunodeficiency virus (HIV) + patients. We describe a case of PJP pneumonia which provided a diagnostic challenge in a patient who presented with no known risk factors leading to a delay in initiation of appropriate antibiotic therapy.
CASE PRESENTATION
A 71-year-old previously healthy white/Caucasian male presented with subacute hypoxic respiratory failure due to multifocal pneumonia with diffuse bilateral ground glass opacities with consolidations despite prior treatment with antibiotics and steroids. He was admitted and started on intravenous broad-spectrum antibiotics but continued to deteriorate, eventually requiring intubation and transfer to the ICU. Bronchoscopy revealed PJP and treatment was initiated, but the patient developed refractory shock and multiorgan failure, and ultimately died. It was later discovered that he was HIV-1 positive.
CLINICAL DISCUSSION
PJP, as a potential cause of his presentation, was not considered given that our patient lacked any overt risk factors for PJP pneumonia. He continued to worsen despite broad spectrum antibiotic therapy and hence bronchoscopy was pursued. His clinical profile, in hindsight, was suspicious for PJP pneumonia and early PJP-directed antibiotic therapy may have prevented a fatal outcome, as in this case. There was an element of cognitive bias across multiple providers which may have contributed to the delay in treatment despite his rapid clinical decline while on conventional pneumonia treatment protocol. His diagnosis was later evident when his BAL-DFA grew PJP in addition to his low levels of CD4 and CD8 cells. He was found to be HIV-1 positive five days after his death; there was a delay in this diagnosis since all positive HIV tests from the hospital are reported as 'pending' until the presumptive positive sample goes to the Connecticut Department of Public Health State laboratory for the confirmatory test. PJP-targeted therapies were initiated later in our patient's hospital course when the infection had progressed to refractory septic shock with multiorgan failure and eventual death.
CONCLUSION
PJP pneumonia is a fatal disease if not recognized early in the course of illness, and the patient usually undergoes multiple antibiotic regimens before they are diagnosed and receive appropriate clinical care. The gold standard of diagnostic testing for PJP is by obtaining bronchial washings through a flexible bronchoscopy and the turnaround time for such results may take a few days to result. A significant proportion of patients may not have any overt risk factors of immunosuppression and early empiric treatment for PJP may be clinically appropriate as the delay in diagnosis may be associated with significant morbidity and mortality risk.
Topics: Humans; Male; Aged; Pneumonia, Pneumocystis; Pneumocystis carinii; Risk Factors; Anti-Bacterial Agents; HIV Infections
PubMed: 38342895
DOI: 10.1186/s13256-024-04350-4 -
Microbiology Spectrum Dec 2022The proposed life cycle of fungi in the genus Pneumocystis has typically included both an asexual cycle via binary fission and a sexual cycle. Until recently, the...
The proposed life cycle of fungi in the genus Pneumocystis has typically included both an asexual cycle via binary fission and a sexual cycle. Until recently, the strategy used for sexual replication was largely unknown, but genomic and functional assays now support a mode known as primary homothallism (self-fertilization). The question of whether an asexual cycle contributes to the growth of these fungi remains. Treatment of Pneumocystis pneumonia in immunosuppressed rodent models with the class of drugs known as echinocandins is challenging the historical concept of asexual replication. The echinocandins target 1,3-β-D-glucan (BG) synthesis resulting in death for most fungi. Because Pneumocystis species have both non-BG expressing life cycle stages (trophic forms) and BG-expressing asci, treatment with anidulafungin and caspofungin resulted in elimination of asci, with large numbers of non-BG expressing organisms remaining in the lungs. Transcriptional analyses of anidulafungin treated Pneumocystis murina-infected lungs indicated that these agents were blocking the sexual cycle. In the present study, we explored whether there was an asexual or alternative method of replication that could rescue P. murina survival and growth in the context of anidulafungin treatment. The effects of anidulafungin treatment on early events in the sexual cycle were investigated by RT-qPCR targeting specific mating genes, including , and . Results from the and gene expression studies clearly indicated there was no rescue by an asexual cycle, supporting these fungi's reliance on the sexual cycle for survival and growth. Dysregulation of mating-associated genes showed that anidulafungin induced effects early in the mating process. The concept of a sexually obligate fungus is unique among human fungal pathogens. This reliance can be exploited for drug development and here we show a proof of principle for this unusual target. Most human fungal pathogens eschew the mammalian environment with its battery of immune responses. Pneumocystis appear to have evolved to survive in such an environment, perhaps by using sexual replication to help in DNA repair and to introduce genetic variation in its major surface antigen family because the lung is the primary environment of these pathogens. The concept of primary homothallism fits well into its chosen ecosystem, with ready mating partners expressing both mating type receptors, and a sexual cycle that can introduce beneficial genetic variation without the need for outbreeding.
Topics: Animals; Anidulafungin; Echinocandins; Ecosystem; Pneumocystis; Pneumonia, Pneumocystis
PubMed: 36287071
DOI: 10.1128/spectrum.02906-22 -
Journal of Medical Microbiology Dec 2021Pathogen-associated molecular patterns' (PAMPs) are microbial signatures that are recognized by host myeloid C-type lectin receptors (CLRs). These CLRs interact with...
Pathogen-associated molecular patterns' (PAMPs) are microbial signatures that are recognized by host myeloid C-type lectin receptors (CLRs). These CLRs interact with micro-organisms via their carbohydrate recognition domains (CRDs) and engage signalling pathways within the cell resulting in pro-inflammatory and microbicidal responses. In this article, we extend our laboratory study of additional CLRs that recognize fungal ligands against and and their purified major surface glycoproteins (Msgs). To study the potential of newly synthesized hFc-CLR fusions on binding to and its Msg. A library of new synthesized hFc-CLR fusions was screened against and organisms and their purified major surface glycoproteins (Msgs) found on the respective fungi via modified ELISA. Immunofluorescence assay (IFA) was implemented and quantified to verify results. mRNA expression analysis by quantitative PCR (q-PCR) was employed to detect respective CLRs found to bind fungal organisms in the ELISA and determine their expression levels in the mouse immunosuppressed Pneumocystis pneumonia (PCP) model. We detected a number of the CLR hFc-fusions displayed significant binding with and organisms, and similarly to their respective Msgs. Significant organism and Msg binding was observed for CLR members C-type lectin domain family 12 member A (CLEC12A), Langerin, macrophage galactose-type lectin-1 (MGL-1), and specific intracellular adhesion molecule-3 grabbing non-integrin homologue-related 3 (SIGNR3). Immunofluorescence assay (IFA) with the respective CLR hFc-fusions against whole life forms corroborated these findings. Lastly, we surveyed the mRNA expression profiles of the respective CLRs tested above in the mouse immunosuppressed Pneumocystis pneumonia (PCP) model and determined that macrophage galactose type C-type lectin (), implicated in recognizing terminal N-acetylgalactosamine (GalNAc) found in the glycoproteins of microbial pathogens was significantly up-regulated during infection. The data herein add to the growing list of CLRs recognizing and provide insights for further study of organism/host immune cell interactions.
Topics: Animals; Mice; Fungal Proteins; Galactose; Host-Pathogen Interactions; Lectins, C-Type; Membrane Glycoproteins; Pneumocystis; Pneumocystis carinii; Pneumonia, Pneumocystis; RNA, Messenger
PubMed: 34889727
DOI: 10.1099/jmm.0.001470 -
Trends in Parasitology Oct 2021The clinical picture of the fungal disease, Pneumocystis pneumonia, resembles the course of coronavirus disease 2019 (COVID-19), presenting a diagnostic challenge in the...
The clinical picture of the fungal disease, Pneumocystis pneumonia, resembles the course of coronavirus disease 2019 (COVID-19), presenting a diagnostic challenge in the pandemic era. We discuss the concern of Pneumocystis jirovecii and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) coinfection, their similarities, and the impact of immunosuppression, with a suggested diagnostic pathway for their suspected coinfection.
Topics: COVID-19; Coinfection; Humans; Immunosuppression Therapy; Pandemics; Pneumocystis carinii; Pneumonia, Pneumocystis
PubMed: 34364804
DOI: 10.1016/j.pt.2021.07.010 -
The Malaysian Journal of Pathology Dec 2020Report of a 3-month old girl child who died due to multi-systemic infection of cytomegalovirus (CMV) involving the lungs, liver and kidneys along with pneumocystis...
Report of a 3-month old girl child who died due to multi-systemic infection of cytomegalovirus (CMV) involving the lungs, liver and kidneys along with pneumocystis jiroveci pneumonia (PJP). The mother of the child tested positive for CMV IgG and HIV with a very low CD4 count (160/ μl). Co-infection of cytomegalovirus and pneumocystis jiroveci always occurs in the setting of immunocompromise. Congenital CMV infection is transmitted through the placenta, especially during the first trimester and causes severe multi-systemic disease whereas perinatal infection is acquired during childbirth/ breastfeeding where the babies have maternal protective antibodies leading to much milder or asymptomatic infection. PJP is more common in infancy and presents as hypoxic pneumonia. CMV causes cyto-nucleomegaly and classic "owl's eye" inclusions on histology while PJP presents with characteristic fluffy "cotton ball" alveolar exudates.
Topics: Coinfection; Cytomegalovirus Infections; Female; Humans; Immunocompromised Host; Infant; Infectious Disease Transmission, Vertical; Pneumocystis carinii; Pneumonia, Pneumocystis
PubMed: 33361734
DOI: No ID Found -
The Journal of Infectious Diseases Sep 2016β-glucans, which can activate innate immune responses, are a major component in the cell wall of the cyst form of Pneumocystis In the current study, we examined whether...
β-glucans, which can activate innate immune responses, are a major component in the cell wall of the cyst form of Pneumocystis In the current study, we examined whether β-1,3-glucans are masked by surface proteins in Pneumocystis and what role β-glucans play in Pneumocystis-associated inflammation. For 3 species, including Pneumocystis jirovecii, which causes Pneumocystis pneumonia in humans, Pneumocystis carinii, and Pneumocystis murina, β-1,3-glucans were masked in most organisms, as demonstrated by increased exposure following trypsin treatment. Using quantitative polymerase chain reaction and microarray techniques, we demonstrated in a mouse model of Pneumocystis pneumonia that treatment with caspofungin, an inhibitor of β-1,3-glucan synthesis, for 21 days decreased expression of a broad panel of inflammatory markers, including interferon γ, tumor necrosis factor α, interleukin 1β, interleukin 6, and multiple chemokines/chemokine ligands. Thus, β-glucans in Pneumocystis cysts are largely masked, which likely decreases innate immune activation; this mechanism presumably was developed for interactions with immunocompetent hosts, in whom organism loads are substantially lower. In immunosuppressed hosts with a high organism burden, organism death and release of glucans appears to be an important contributor to deleterious host inflammatory responses.
Topics: Animals; Antifungal Agents; Caspofungin; Cytokines; Disease Models, Animal; Echinocandins; Lipopeptides; Mice, Knockout; Microarray Analysis; Pneumocystis; Pneumonia; Pneumonia, Pneumocystis; Real-Time Polymerase Chain Reaction; beta-Glucans
PubMed: 27324243
DOI: 10.1093/infdis/jiw249 -
Medecine Sciences : M/S 2012Is Pneumocystis pneumonia (PcP) a transmissible fungal disease? Does nosocomial PcP occur? Is there Pneumocystis transmission in the community? These questions, which... (Review)
Review
Is Pneumocystis pneumonia (PcP) a transmissible fungal disease? Does nosocomial PcP occur? Is there Pneumocystis transmission in the community? These questions, which could not be tackled before the 2000s, may at present be approached using either noninvasive detection methods or experimental transmission models. Represented by a unique entity (P. carinii) for almost one century, the Pneumocystis genus was shown to contain several species, being P. jirovecii the sole species identified in humans hitherto. Molecular methods combined with cross infection experiments revealed strong host specificity that precludes Pneumocystis inter-species transmission. In contrast, respiratory transmission between mammals of a same species is usually highly active, even between immunocompetent hosts. Other transmission ways could also exist. New data show that human being is the unique P. jirovecii reservoir; it would constitute the sole infection source in both hospital and community.
Topics: Animals; Cross Infection; Humans; Infectious Disease Transmission, Vertical; Models, Biological; Pneumocystis; Pneumocystis Infections; Pneumonia, Pneumocystis
PubMed: 22805135
DOI: 10.1051/medsci/2012286012