SCIENTIFIC ACTIVITIES - ABOUT PNEUMOCYSTIS

This multicenter study found DHPS mutations in 68.5% of Pneumocystis carinii isolates from HIV-infected patients with PCP, strongly associated with sulfa/sulfone prophylaxis and geographic location. The high prevalence of mutations even in prophylaxis-naïve patients suggests possible person-to-person or environmental transmission of resistant strains.

This study characterizes the early-life lower airway microbiome in 53 infants, revealing dynamic changes in fungal and bacterial communities during the first year of life. Findings identify 2–4 months as a critical window, where asymptomatic Pneumocystis jirovecii colonization may act as an ecological driver influencing microbial equilibrium and long-term respiratory health.

This review traces the evolutionary history of Pneumocystis jirovecii, suggesting its origin from environmental ancestors during the Cretaceous and subsequent adaptation to mammals through massive gene loss. The species cospeciated with primates around 65 million years ago, with molecular evidence indicating chromosomal rearrangements and genetic barriers driving its specialization to humans.

This study sequenced and compared genomes of Pneumocystis species from diverse mammalian hosts, providing robust phylogenies and insights into host adaptation mechanisms. The findings illuminate the evolutionary history of P. jirovecii, the only species infecting humans, and clarify its divergence in relation to mammalian speciation.

This review summarizes recent genomic advances in Pneumocystis species, highlighting subtelomeric regions enriched in glycoprotein-encoding genes that drive surface antigenic variation. These findings provide new insights into mechanisms of immune evasion and host adaptation, underscoring antigenic variation as a central virulence strategy in these obligate fungal pathogens.

This study presents near-complete genome assemblies of three Pneumocystis species, revealing compact genomes lacking key fungal cell wall components such as chitin and outer chain N-mannans. The data highlight unique adaptations to exclusive growth in mammalian lungs, including metabolic dependence and expanded surface glycoprotein families for immune evasion.

This study reports the first successful whole-genome sequencing of Pneumocystis jirovecii using immunoprecipitation enrichment and next-generation sequencing, yielding an 8.1-Mb draft genome. These findings provide a critical resource for advancing research on its biology, transmission, and the development of novel therapeutic and vaccine targets.

This report describes two HIV-infected patients in whom co-trimoxazole prophylaxis or treatment failed, with detection of Pneumocystis carinii DHPS gene mutations. These findings support concerns that sulphonamide resistance may emerge under prophylactic pressure, threatening the efficacy of standard PCP prevention strategies.

This study analyzed ITS regions of Pneumocystis carinii sp. f. hominis from HIV-infected patients, identifying ten genetic types across 24 pneumonia episodes. Findings revealed frequent mixed infections and showed that recurrent cases may result from both reactivation of latent strains and reinfection from exogenous sources.

This study aimed to assess whether Pneumocystis jirovecii can be transmitted transplacentally from immunocompetent mothers to fetuses using molecular assays. It demonstrated the presence of P. jirovecii DNA at two gene loci in lung tissues of 35% of fetuses and placentas of 5%, providing molecular evidence of vertical transmission. These findings suggest that P. jirovecii may cross the placental barrier in humans, warranting further investigation into its potential role in miscarriage or fetal compromise

This study determines that Pneumocystis carinii circulates between immunocompromised and immunocompetent hosts, causing pneumonia in the former and asymptomatic carriage in the latter. Two main transmission routes are suggested: between immunocompromised patients and from them to closely exposed immunocompetent individuals. Other possibilities, such as spread from carriers or environmental sources, cannot be excluded. Further studies are needed to clarify these transmission dynamics.

This study provides molecular evidence that airborne person-to-person transmission of P. carinii sp. f.hominis is possible, thus suggesting that patients with PCP should not come into close contact with immunocompromised persons. Immunocompromised patients who are not receiving PCP prophylaxis should not enter the room of a patient with PCP. The data show that the immunocompetent contacts of patients with PCP can acquire transient colonization by the organism.

This study demonstrates that PCR amplification of Pneumocystis carinii DNA from bronchoalveolar lavage is highly sensitive and specific, detecting cases missed by conventional staining. The findings establish PCR as a valuable diagnostic and epidemiological tool for P. carinii infection in immunosuppressed patients.

This study determines that pulmonary colonization with Pneumocystis carinii occurs in HIV-negative patients, with an estimated prevalence of 14%. Colonization is significantly associated with reduced CD4+ T-cell counts and inverted CD4/CD8 ratios. Importantly, no cases progressed to pneumonia, underscoring colonization as a marker of impaired cellular immunity rather than overt infection.

Pneumocystis carinii infection was identified in patients with chronic bronchial disease, underscoring its potential role as a contributory pathogen beyond classical immunocompromised settings. Clinical and diagnostic observations indicate that P. carinii may exacerbate respiratory decline. These findings suggest the need to reconsider its epidemiological and pathological significance in chronic airway disorders.

This study shows that prolonged sulfa or sulfone prophylaxis in AIDS patients with PCP is strongly associated with Pneumocystis carinii DHPS mutations, detected in 76% of exposed cases. While most patients with mutations still responded to therapy, their presence significantly increased the risk of treatment failure.

This study evaluated whether point mutations in the Pneumocystis carinii DHPS gene, a key enzyme in folate biosynthesis, are linked to prior sulpha drug exposure. The findings assess their potential impact on treatment efficacy and clinical outcomes in HIV-1 patients with PCP.

This study reviews the reclassification of the human pathogen as Pneumocystis jirovecii, emphasizing its genetic distinctness and diversity across host species. Evidence of sequence variation suggests transient colonization rather than lifelong latency, reshaping concepts of host–pathogen interaction.

This study shows that nested PCR of oropharyngeal samples targeting the mtLSU rRNA of Pneumocystis carinii sp. f. hominis enables non-invasive monitoring of treatment response in HIV patients with PCP. ITS sequence typing proved consistent with bronchoalveolar lavage results, supporting its value as a reliable, less invasive tool for diagnosis and epidemiological studies.

This study examines the biology and epidemiology of Pneumocystis jirovecii, the human-specific species of the genus Pneumocystis. It highlights its genetic diversity, strain variability, and the potential for both recent infection and long-term colonization. The findings underscore unresolved questions regarding transmission routes and infection sources, pointing to the need for further investigation.

This study evaluated the humoral immune response to Pneumocystis carinii in 122 confirmed cases of pneumonia, comparing AIDS and non-AIDS immunosuppressed patients. Results showed that AIDS patients largely failed to mount a detectable antibody response, in contrast to other immunosuppressed individuals who frequently seroconverted. These findings indicate that serology has limited diagnostic value in AIDS but may complement clinical diagnosis in other immunocompromised populations when paired sera are analyzed.

This study addresses the taxonomic uncertainty of Pneumocystis carinii, the most frequent opportunistic infection in AIDS, by analyzing its 16S-like rRNA sequences. Phylogenetic comparisons place the organism within the fungal lineage, rather than among protozoa as previously debated. These findings redefine its biological classification and provide a framework for understanding its evolutionary relationships and pathogenicity.

This study sequenced rRNA genes and ITS regions of human-derived Pneumocystis carinii, revealing high conservation in rRNA genes but marked variability in ITS1 and ITS2. The findings demonstrate strain diversity, classification into distinct groups, and evidence of coinfection with multiple P. carinii strains within individual patients.