Prevalence of yeast-like fungi and evaluation of several virulence factors from feral pigeons in Seoul, Korea

Aims: Studies of pigeon-borne yeasts have tended to focus on species, such as Cryptococcus neoformans and Candida albicans, with scant attention to feral pigeons in Korea. We studied the prevalence of yeasts from faecal samples of feral pigeons obtained in various public places in Seoul, Korea, and assessed their potential capacity as human pathogens. Methods and Results: Three hundred and six pigeon faeces samples were collected at city squares and parks in 21 localities in Seoul and Seoul Grand Park and analysed for yeast with conventional methods. Of the 306 samples, 126 (41 center dot 2%) were positive for yeast. Seventeen species of yeast were identified. The most frequent species were Candida glabrata (34 center dot 1%), Candida famata (12 center dot 7%), Cryptococcus albidus (14 center dot 3%) and Cryptococcus laurentii (7 center dot 9%). The yeast isolates were tested for virulence. Of the 116 isolates (ten isolates missing), 70 center dot 7% (n = 82) grew at 37 degrees C. All the Cryptococcus spp. isolates possessed a capsule, 16 center dot 4% (n = 19) produced melanin, and 33 center dot 6% (n = 39) produced proteinase. Two Ca. glabrata, a Ca. famata and Ca. albicans as well as three C. neoformans, a C. laurentii and Ca. albicans isolates had three virulence factors. Accordingly, 29 center dot 3% (n = 34) isolates possessed more than two virulence factors except capsule formation. Conclusions: These results of this study indicate that feral pigeons harbour a variety of yeasts and are a reservoir of human pathogenic fungi. Significance and Impact of the Study: This study is the first time about the microflora (fungi) presents in faecal samples collected from a variety of public areas throughout Seoul, Korea.