Illuminating Biofilm Formation and Pathogen Persistence in Household Refrigerators: Evidence from Karachi, Pakistan

Abstract

In the modern household, refrigerators play a central role in preserving food freshness. However, the microbial landscape within these appliances, particularly the formation of biofilms, remains a significant concern for food safety and hygiene. This study investigated biofilm formation in household refrigerator environments to understand the potential risks associated with microorganisms and their implications for food safety. The study was conducted by examining a total of 80 refrigerators of residents of Karachi, over a 15-day period. employing rigorous methodologies to assess optical density (OD), Colony Forming Units (CFU/cm²), and Scanning Electron Microscopy (SEM) to uncover bacterial species' abilities to develop biofilms. Results revealed that 12 out of the 80 slides displayed positive biofilm formation based on both OD and CFU criteria. Strong biofilm producers encompassed Acinetobacter, Listeria, P. aeruginosa, E. coli, Bacillus, Salmonella, and others. Notably, P. aeruginosa was a common component across different biofilm categories. In vitro studies on individual isolates further confirmed biofilm-forming capabilities. P. aeruginosa isolates exhibited strong biofilm formation, while E. coli isolates displayed weak capabilities. Enterococci isolates generally formed weak to moderate biofilms. In summary, our study reveals the prevalence of biofilm formation in household refrigerators, with significant microbial risks posed by species like P. aeruginosa. These findings underscore the importance of stringent hygiene practices for ensuring food safety at home.