Isolation and identification of yeasts found in selected urban wastewater and assessment for in vitro antimicrobial resistance

• Main Authors: Arive, Jana Karissa O., Benedicto, Angelo James M., Castro, Keesha Mikaela B., Ibay, Juliana Rae M., Llamas, Martha Alia M.
• Format: text
• Language: English
• Published: Animo Repository 2024
• Subjects: Sewage—Microbiology; Anti-infective agents; Candida tropicalis; Yeast; Microbiology
• Online Access: https://animorepository.dlsu.edu.ph/etdb_bio/82
• Institution: De La Salle University

The prevalence of antimicrobial resistance is quickly becoming a global health crisis, especially due to humans’ constant exposure to different pathogenic microorganisms, including yeasts. With this, further studies on antimicrobial resistance are important in determining effective prevention and treatment of infections caused by such pathogens. This study aimed to assess the antimicrobial susceptibility against azole drugs of yeasts isolated from urban wastewater samples. In addition, identification of the yeast isolates in wastewater was also conducted using phenotypic methods such as Gram staining and germ tube assay, as well as genotypic methods through molecular sequencing. A total of 20 presumptive yeast colonies based on colony morphology and microscopic analysis were isolated and further purified. Sequencing of the Internal transcribed spacer (ITS) 4 and 5 regions for molecular sequence analysis confirmed the following species: (i) Candida glabrata, (ii) Candida tropicalis, and (iii) Candida nivariensis. Results of the antimicrobial susceptibility testing revealed that five isolates were susceptible-dose-dependent (SDD) and fifteen isolates were susceptible to both fluconazole (25 ug) and voriconazole (1 ug). This study sheds light on the current antimicrobial resistance patterns of yeast species in wastewater collected from DLSU-Manila. Keywords: Urban wastewater, antimicrobial resistance, Candida glabrata, Candida tropicalis, Candida nivariensis, voriconazole, fluconazole