Microbial Bioburden of Bathroom Door Handles at California State Polytechnic University, Pomona
Mentor:Shelton Murinda, Associate Professor of Animal and Veterinary Sciences , California State Polytechnic University Pomona
Centers for Disease Control and Prevention flyers on handwashing are posted on bathroom walls across our campus, but not everyone heeds their advice. We were concerned about the microbial bioburden of the door handles leading out of the bathrooms, especially that there could be pathogenic E. coli or other coliforms present. If they were present, it would be a public health hazard that would need to be addressed by our campus. We tested our concerns over a period of three months by using sterile cotton tipped applicators and buffered peptone water to swab the door handles of the men’s and women’s bathrooms of eighteen buildings across campus and let them incubate for 24 hours. Samples from tubes that showed growth were streaked for isolation on McConkey Lactose agar and incubated for another 24 hours. Plates that demonstrated lactose fermentation were plated on Tryptic Soy Agar, and colonies were isolated, and preserved. We performed polymerase chain reaction (PCR) on the positive samples testing for the lacZ gene, which confirmed the presence of coliforms, and the uidA gene, which was used to confirm the presence of E. coli. After E. coli was confirmed, we planned to use multiplex PCR analysis to test for the presence of pathogenic (diarrehagenic) clones of E. coli namely, Shiga toxin-producing, enteropathogenic, enterotoxigenic, enteroinvasive, enteroaggregative, and diffuse adherent E coli. After gathering samples for three months, we had a total of 84 isolates that grew on the McConkey Lactose agar. After performing PCR, seventeen of those isolates were confirmed as coliforms (0.04% positive samples), and of those, one was identified as E. coli (0.002% positive samples). We confirmed the presence of coliforms and E. coli in the bathrooms at Cal Poly Pomona. This confirms that there is a public health risk, and students need to be informed.