This research was done at UZIMA University of Health and Social Sciences, which is located in Kisumu County, in Western Kenya. The University offers undergraduate courses in various disciplines such as Medicine, Nursing, Clinical medicine, Microbiology, Health records and Community health.
An experimental study design was adopted where a total of 16 mobile phones were randomly selected from students. The primary outcome was to isolate Staphylococcus aureus from surfaces of mobile phones. These phones were obtained from students of Microbiology and Biomedical Laboratory Sciences from UZIMA University of Health and Social Sciences, Kisumu (Kenya) and the University Colleges Leuven- Limburg, Leuven (Belgium), respectively. The research was part of an annual international project between the two academic institutions to enhance student linkages and experience on practical aspects in the field of microbiology.
Swabs from surfaces of mobile phones were collected using disposable sterile cotton swabs moistened with sterile normal saline.
Approximately 1.84 g of nutrient agar (Fisher Scientific, Leicestershire, UK) was weighed and dissolved in 80mls of distilled water in a glass beaker. The glass beaker was heated until the agar was completely dissolved. The media was sterilized by autoclaving at 121 °C for 15 minutes. Mobile swabs were plated onto nutrient agar and incubated at 37 °C for 24 h. After incubation, the colonies were identified by their characteristic appearance on nutrient agar.
Gram staining was used for differentiation of Gram-positive and Gram-negative bacteria by microscopy. Smears were made on microscopic slides from the colonies. The smears were air-dried and heat fixed and flooded with crystal violet (Fisher Scientific, Leicestershire, UK) staining reagent for 1 minute. The slides were then washed gently in running water for 2 seconds. The slides were then flooded with gram’s iodine (Fisher Scientific, Leicestershire, UK) for 1 minute and thereafter washed in a gentle and indirect stream of tap water for 2 seconds. The slides were decolorized for 15 seconds with acetone (Fisher Scientific, Leicestershire, UK) and counterstained with safranin (Fisher Scientific, Leicestershire, UK) for 1 minute. The slides were finally washed in running water and blotted on an adsorbent filter paper.
The catalase method was used to differentiate Staphylococci from Streptococci bacteria. Briefly, a small amount of bacterial colony was added to a glass using a sterile loop. A drop of 3% H202 (Fisher Scientific, Leicestershire, UK) was then added onto the slide and mixed with the colony.
The coagulase method was used as a confirmatory test for Staphylococcus aureus. A drop of staphylococcal colony was emulsified on a glass slide. A sterile wire loop was dipped into undiluted plasma and then emulsified onto the staphylococcal suspension. Coarse clumping was confirmatory for Staphylococci aureus.
The Kirby-Bauer disc diffusion susceptibility test method was used to determine the sensitivity or resistance of bacteria to antibiotics. Mueller-Hinton agar (Fisher Scientific, Leicestershire, UK) was prepared by weighing 1.84 g of agar in 80 ml of distilled water. The media was briefly heated on a Bunsen burner flame to dissolve and autoclaved as previously described. The media was then dispensed on agar plates and left to solidify. An inoculum was prepared as follows: A sterile inoculating loop was used to pick colonies of the test organism and suspended in 2 ml sterile saline in a tube. A sterile swab was dipped into the inoculum tube and rotated against the side of the tube. The dried surface of the Mueller-Hinton agar plate was inoculated by streaking the swab three times over the entire surface. The antimicrobial impregnated disks (Sigma-Aldrich, Missouri, USA) were placed on the surface of the agar plates using a pair of sterile forceps. The plates were placed inverted in an incubator for 24 hrs. The zones of inhibition were measured in mms and the results were scored as resistant, intermediate or susceptible based on the Clinical Laboratory Standards Institute Performance Standards for Antimicrobial Disk Susceptibility Tests.