Isolation of Gram-Positive, Antibiotic-Resistant Bacteria from Tactile Mobile Phones in a Northwestern Mexican City.

The widespread use of touch-screen mobile devices renders them potential fomites for the transmission of bacterial pathogens among users of different ages. The objectives of the present research were to isolate bacteria from mobile phones, perform molecular and phylogenetic identification, and determine the antibiotic resistance profiles. The surfaces of 50 touch-screen mobile devices owned by bystanders were sampled in the city center of Culiacan, Sinaloa, Mexico. The samples were cultured on nutritive agar; 13 bacterial colonies were isolated and characterized based on their macroscopic and microscopic characteristics and then identified using PCR amplification and sequencing of the 16S rRNA gene V4 and V6 regions. Their taxonomic relationships were determined via a Bayesian inference approach. Antimicrobial resistance was evaluated via disc diffusion and broth microdilution assays. Species of the genera Staphylococcus, Bacillus, and Enterococcus were identified on 84.6, 7.7, and 7.7% of the mobile phones, respectively. A unique subgroup of Staphylococcus epidermidis was identified in strains FBOPL-23, CAEPL-28, and FREPL-28. Staphylococcus hominis novobiosepticus was also identified on mobile phones for the first time. Of the isolated bacteria, 92.3% were resistant to erythromycin, 76.9% to ampicillin and penicillin, 61.5% to dicloxacillin, 38.5% to cephalothin and 7.7% to cefotaxime and ceftriaxone. The presence of antibiotic-resistant bacteria of clinical relevance poses potential risks to users' health and the dissemination of antibiotic resistance mechanisms throughout the community; thus, we recommend regular cleaning to prevent cross-infection by multidrug-resistant bacteria when using touch-screen mobile devices.