Molecular detection ofPneumocystisin the lungs of cats

Abstract

The genus Pneumocystis comprises potential pathogens that reside normally in the lungs of a wide range of mammals. Although they generally behave as transient or permanent commensals, they can occasionally cause life-threatening pneumonia (Pneumocystis pneumonia; PCP) in immunosuppressed individuals. Several decades ago, the presence of Pneumocystis morphotypes (trophic forms and cysts) was described in the lungs of normal cats and cats with experimentally induced symptomatic PCP (after immunosuppression by corticosteroids); yet to date spontaneous or drug-induced PCP has not been described in the clinical feline literature, despite immunosuppression of cats by long-standing retrovirus infections or after kidney transplantation. In this study, we describe the presence of Pneumocystis DNA in the lungs of normal cats (that died of various unrelated causes; n = 84) using polymerase chain reactions (PCRs) targeting the mitochondrial small and large subunit ribosomal RNA gene (mtSSU rRNA and mtLSU rRNA). The presence of Pneumocystis DNA was confirmed by sequencing in 24/84 (29%) cats, with evidence of two different sequence types (or lineages). Phylogenetically, lineage1 (L1; 19 cats) and lineage 2 (L2; 5 cats) formed separate clades, clustering with Pneumocystis from domestic pigs (L1) and carnivores (L2), respectively. Results of the present study support the notion that cats can be colonized or subclinically infected by Pneumocystis, without histological evidence of damage to the pulmonary parenchyma referable to pneumocystosis. Pneumocystis seems most likely an innocuous pathogen of cats' lungs, but its possible role in the exacerbation of chronic pulmonary disorders or viral/bacterial coinfections should be considered further in a clinical setting.

Predicting Species Boundaries and Assessing Undescribed Diversity in Pneumocystis, an Obligate Lung Symbiont

“…Two of the most devastating emerging diseases of wild animals are fungal: amphibian Chytridiomycosis ( Batrachochytrium dendrobatidis ) and White Nose Syndrome ( Pseudogymnoascus destructans ) of bats. The struggle to understand these previously obscure fungi has slowed progress towards treatment development, demonstrating the importance of basic research into fungal pathogens [ 65 ], while assumptions of host specificity in Pneumocystis have led researchers to discount the possibility of disease spillover from host jumps between distantly related taxa, instances of closely related fungal species colonizing domestic cats and pigs suggests it can occur [ 66 ]. The example of cat and pig Pneumocystis is especially interesting, since both animals are domesticated and have not had opportunity for close contact until fairly recently, following their domestication.…”

Detection of Pneumocystis and Morphological Description of Fungal Distribution and Severity of Infection in Thirty-Six Mammal Species

“…have been found in the lungs of a wide variety of mammals [ 1 , 4 ]. Members of the mammal orders Artiodactyla [ 5 , 6 , 7 , 8 , 9 ], Carnivora [ 10 , 11 , 12 , 13 ], Chiroptera [ 14 ], Eulipotyphla [ 7 , 15 , 16 ], Perissodactyla [ 17 ], Primates [ 18 ], and the clade Glires consisting of the orders Lagomorpha and Rodentia [ 19 , 20 ] have been investigated during the last decades. Nevertheless, depending on the study focus, different Pneumocystis detection methods have been used, making the comparison of data difficult.…”

Pneumocystis Colonization in Dogs Is as in Humans

“…Although Pneumocystis is best known as a cause of severe disease in immunocompromised patients, the organism far more often acts as a transient or permanent commensal, colonizing limited portions of the lungs, while causing minimal or no damage to the host [ 20 , 21 ]. Thus, colonization and/or subclinical Pneumocystis infection may occur in immunocompetent dogs, cats and humans, including patients that have died of various causes unrelated to PCP carriage (such as vehicular trauma, chronic kidney disease or systemic viral illness) [ 22 , 23 ].…”