Phenotypic and Genotypic Characterization with MALDI-TOF-MS Based Identification of Staphylococcus spp. Isolated from Mobile Phones with their Antibiotic Susceptibility, Biofilm Formation, and Adhesion Properties

Abstract

Cell phones, smartphones, and tablets are extensively used in social and professional life, so they are frequently exposed to bacteria. The main goal of the present work was to isolate and characterize Staphylococci strains from students’ cell phone mobiles. Subsequently, 24 Staphylococci strains were tested against a wide range of antibiotics, for the distribution of some virulence-related genes and their ability to form biofilm. Staphylococcus spp. were cultured from all studied devices on chromogenic medium and identified using the matrix-assisted laser desorption/ionization (MALDI), time-of-flight (TOF) mass spectrometry (MS) technique (MALDI-TOF-MS). The results obtained showed that S. aureus was the dominant species (19 strains, 79.1%), followed by S. warneri (3 strains, 12.5%), and S. haemolyticus (2 strains, 8.3%). Isolated strains showed high percentages of hydrolytic enzymes production, resistance to many tested antibiotics, and 37.5% expressed the mecA gene. The tested strains were highly adhesive to polystyrene and glass and expressed implicated icaA (62.5%) and icaD (66.6%) genes. All Staphylococcus spp. strains tested were found to possess proteases and the α-hemolysin gene. Our results highlighted the importance of mobile phones as a great source of Staphylococcus spp., and these species were found to be resistant to many antibiotics with multiple antibiotic resistance (MAR) index ranging from (0.444) to (0.812). Most of the studied strains are able to form biofilm and expressed many virulence genes. Phylogenetic analysis based on the phenotypic and genetic characters highlighted the phenotypic and genetic heterogeneity of the S. aureus population studied. Further analyses are needed to elucidate the human health risks associated with the identified Staphylococci strains.

Molecular Characterization of Staphylococcus aureus Strains Isolated from Mobile Phones

“…Finally, the high genetic variability prevailing in the S. aureus strains isolated from students and their MP ( Table 2 , Figure 2 ) is consistent with the evidence proposed by other studies; this variability is also observed among humans and MP [ 20 , 56 ]. This implies a high number of different S. aureus strains circulating in the environment, so epidemiological surveillance studies of S. aureus should continue to be carried out.…”

“…The predominant adhesin genes identified in the studied strains of the students and their MP were icaD , clfB , sdrC , and cna ( Table 2 and Table 3 , Figure 2 ). Something similar was documented by Noumi et al, since they also found a high percentage of MP strains that presented the icaD , can , and fnbA genes [ 56 ]. Nevertheless, we found that the fnbA gene is present in a higher percentage in pharynx strains than in those isolated from MP ( Table 3 ).…”

Bacterial contamination of the smartphones of healthcare workers in a German tertiary-care hospital before and during the COVID-19 pandemic

“…Bacterial contamination of SP surfaces is affected by various factors such as sebum, sweat, saliva, fat, food residues, and make-up. 15 , 21 When comparing both study periods, the spectrum of bacteria was very similar. However, bacteria known for airborne transmission were detected more frequently in 2021, as well as polymicrobial contamination.…”

“…Bacterial contamination of SP surfaces is affected by various factors such as sebum, sweat, saliva, fat, food residues, and make-up [15,21]. When comparing both study periods, the spectrum of bacteria was very similar.…”

MALDI-TOF MS: application in diagnosis, dereplication, biomolecule profiling and microbial ecology

“…The ribosomal protein spectra are microbe specific, as in case of rep-PCR, and hence these could be a potential tool for dereplication (Barthélemy et al 2020 ). Additionally, this technique has also its application in the accurate identification of organisms isolated from varied environments such as biofilm habitats (Gaudreau et al 2018 ), cellular phones (Noumi et al 2020 ), spacecraft surfaces (Seuylemezian et al 2018 ) and in nosocomial settings (De Florio et al 2018 ). Furthermore, it has revolutionized the field of disease diagnostics by identifying the varied mammalian cell types, circulating immune cells without using cell specific antibodies thus making diagnostic procedures more effective and affordable (Munteanu and Hopf 2013 ).…”