Investigation of key virulence factors in Candida parapsilosis isolated from subclinical bovine mastitis cases in Baghdad Governorate

Mastitis is a serious economic disease that can be caused by fungal pathogens from the genus Candida. This study aimed to isolate and identify Candida parapsillosis from subclinical cases of bovine mastitis and to evaluate its main virulence factors, including proteinase production (using albumin and casein as substrates), haemolytic activity, urease production, and biofilm formation. Between November 2023 and March 2024, fifty milk samples were collected from various locations within Baghdad Governorate and the surrounding suburban farms of Abu-Ghraib. Each milk sample was tested for the California Mastitis Test (CMT). The results showed that 84% of the samples were positive for CMT. Forty-four mycotic isolates were identified, including six isolates of Candida spp. (33.3%), of which two were Candida parapsilosis (4.5%), along with several other fungal species. All of Candida parapsilosis isolates were identified macroscopically by culturing on Sabouraud Dextrose Agar (general medium), CHROM Agar and BIGGY Agar (special, selective and differential media) at 37C and 25ºC for 3-5 days and microscopically using lactophenol cotton blue stain. This study demonstrated that C. parapsilosis exhibited several virulence factors, including the ability to degrade albumin, hydrolase urea, produce haemolytic activity on Blood Agar and form biofilms, but was unable to degrade casein. The findings indicate that cow milk contains various types of fungi, including molds and yeasts. Importantly, the yeast species identified were not limited to C. albicans but also other Candida species, with a notable prevalence of C. parapasilosis. This species may act as an opportunistic pathogen in bovine mastitis.