Nested–polymerase chain reaction detection of Pneumocystis carinii f. sp. canis in a suspected immunocompromised Cavalier King Charles spaniel with multiple infections

Petini, Matteo; Furlanello, Tommaso; Danesi, Patrizia; Zoia, Andrea

The genus Pneumocystis contains highly diversified and opportunistic fungal species that cause severe pneumonia in mammals with a deficient immune system. 1 In the veterinary literature, there are many published cases of confirmed canine pneumocystosis-most of which described cases of young to middle-age dogs with suspected immunodeficiency, with the Miniature Dachshund, and the Cavalier King Charles Spaniel (CKCS) breeds most commonly reported. [1] [2] [3] [4] [5] [6] [7] [8] Concurrent infection with other pathogens has been reported in only a few cases when concurrent Demodex canis 3, 5, 7 and canine distemper virus (CDV) 3 infections were demonstrated. In most of the previously reported veterinary cases, in vivo diagnosis of Pneumocystis spp. pneumonia (PP) was achieved by direct identification of the microorganism by cytological examination of bronchoalveolar lavage (BAL) samples, trans-tracheal aspirates, or transthoracic lung aspirates. 2 However, using this technique, the diagnosis can be missed due to failure on detection of the lung pathogen. 2, 4, 6, 9 In human medicine, several studies have demonstrated that polymerase chain reaction (PCR)-based methods increase the sensitivity of detection of the organism compared to its direct identification on lung samples. 10, 11 Indeed, real-time PCR has been recently recommended for PP diagnosis by a European panel of experts. 12 The aim of this report was to describe the first case of Pneumocystis carinii f. sp. canis infection in a suspected immunocompromised CKCS, with four concurrent pulmonary infective agents and one extrapulmonary infectious agent. In this case, an in vivo identification of Pneumocystis spp. was achieved by PCR testing of BAL fluid, in which no Pneumocystis cysts had been identified with cytological examination.