Microbiology Acta Spartae Vol. 2 No. 1 2016 Pages 14–15 Comparison of Antibiotic Susceptibility of Bacterial Communities on Cell Phones Belonging to Health Care Workers and Non-Health Care Workers Matt Guillemette, Zachary Rivera, and Eric Freundt 1 Department of Biology, University of Tampa, Tampa, FL 33606, 1 Faculty Advisor ABSTRACT The frequent use of cell phones inside of health care facilities produces a risk of contamination of the phones with potentially pathogenic bacteria. The elevated use of antibiotics within these health care facilities may also contribute to heightened levels of antibiotic resistant strains on these devices. To assess this, bacterial samples were collected from health care workers’ and non-health care workers’ cell phones. The bacterial isolates were assessed for antibiotic resistance via the Kirby-Bauer method. Eleven out of nineteen of the bacterial isolates from the health care workers cell phones displayed resistance to at least one antibiotic. According to our study, the lower amount of resistance of the bacteria isolated from the health care worker samples compared to the non-health care worker samples leads us to conclude that there is not a higher prevalence of antibiotic resistant bacteria on health care workers’ phones. 1 INTRODUCTION Bacterial cells are found on every surface from cell phones to the kitchen counter. The average bacterial cell is 1–4 micrometers in diameter. This means that about one million bacterial cells will take up the same amount of area as one grain of sand. If one million bacterial cells can fit in the same area as a grain of sand then the amount of bacteria that can fit on a cell phone surface would be astronomical. Sterile bacterial swabs of cell phones have been conducted and several colonies of bacteria have been isolated (Akinyemi et al., 2009). Furthermore, computer keyboards were swabbed for bacterial growth and produced results similar to those of cell phones (Sergio et al., 2000). Individuals are in contact with these two surfaces multiple times every day which could be leading to increased rates of bacterial infection. Health care workers should be extremely careful when using their cell phones in the hospital because of their increased level of exposure to drug-resistant strains of bacteria. A study of 200 health care workers demonstrated that 94.5% of their cell phones exhibited evidence of bacterial contamination (Ulger et al., 2009) There is evidence that cell phones contain the same bacterial contamination that peoples hands do thus acting has successful fomites. Cell phones have been proven to be effective in transporting bacteria, which can be how these bacterial infections are spreading (Noskin et al., 1995). Knowing that cell phones are effective mechanisms for bacteria transport, effective methods for cell phone disinfection should be studied. Previous work has shown that bacteria are able to survive on fingertips for at least 60 minutes (Pal et al., 2015), it is rational to believe that there is bacterial contamination all over cell phones. This was the focus of investigation in the following experiment. In this study, we isolated and cultured several species of bacteria from cell phones used in every day environments and compared the results to cell phones that are used within the healthcare environment. Upon determining the differences in colony morphologies, we tested the bacteria for resistance against two antibiotics. The two antibiotics used were erythromycin and ampicillin. Erythromycin is an antibiotic that affects gram-positive strains of bacteria much more efficiently than gram-negative strains. It was shown that the uptake of erythromycin by gram-positive species was 100 times greater than that of gram- negative species (Mao & Putterman, 1968). There was a close relationship between the accumulation of erythromycin and the ability to inhibit the growth of gram-positive bacteria. Ampicillin is considered to be a beta-lactam antibiotic and has been proven to treat both gram-positive and gram-negative species of bacteria. The ability for beta-lactam drugs to inhibit the growth of bacterial species is dependent upon binding to specific targets located in the cytoplasmic membrane of the bacteria (Knowles, 1985). Binding of beta-lactam drugs to target proteins results in the inability for bacteria to synthesize a peptidoglycan cell wall, ultimately causing cell rupture. More specifically, the acylation of a serine hydroxyl group at the active site is what results in inactivation of the cell-wall synthesizing protein (Knowles, 1985). Antibiotic resistance is becoming an increasingly common feature of bacterial species. There are several ways that they can become resistant. First, the target enzymes may become less susceptible to acylation, which inhibits inactivation of the protein. Another way is through changes in the outer membrane permeability resulting in the inability for the drug to penetrate the cell wall and reach the target protein in the cytoplasm. However, the most common method of resistance is specific toward beta-lactam antibiotics. The appearance of the enzyme beta-lactamase results in destruction of the antibiotic before it can reach the target protein within the bacterial cell (Malouin & Bryan, 1986) In this study, we assessed whether or not the cellphones of healthcare professionals are more susceptible to becoming contaminated with drug-resistant bacteria than phones in community settings. 2 MATERIALS AND METHODS Bacterial samples were collected from cell phones that were frequently used inside of a long term health care facility (labeled Hospital). The samples were collected from 8 volunteers who perform various tasks such as cleaning and observing patient- doctor interactions. Also samples from various phones that are 14 © 2016 Matt Guillemette, Zachary Rivera, and Eric Freundt, published with permission