Presence of Methicillin Resistant Staphylococcus aureus on Dental Student Laptops

Objectives: This study evaluated the presence of methicillin resistant Staphylococcus aureus (MRSA) on Second Year (pre-clinical) dental student (2YDS) personal laptop computers before and after daily or weekly disinfection procedures. Methods: Experimentation involved two groups. First, 52 2YDS laptop computers underwent a series of weekly disinfections three times. The second group included 33 2YDS laptops that received daily disinfection for one week. Prior to disinfection, sampling of the top surface of each laptop involved physiological buffered saline (PBS) moistened cotton swabs. These then went into tubes containing 2.0 mL of PBS and vortexed for 15 seconds. Using a spiral plater, the solutions went onto enriched trypticase soy agar (ETSA) and mannitol salt agar (MSA) plates. Incubation was aerobic at 37oC for 48 hours. Sub-culturing of colony types was in trypticase soy broth followed by spread plating onto MSA, ETSA with cefotaxime discs, oxacillin resistance screening agar and MRSA selective agars - CHROMagar and MRSASelect - followed. Counting colonies occurred after incubation. The first group received three weekly disinfection procedures with CaviWipes (Metrex, Romulus, MI), while disinfection of the second group was daily for one week. Sampling and plating that then occurred was as previously described. Results: Pre-disinfection specimens from 2YDS daily (2YDS weekly in parenthesis) laptops produced 127 (109) isolates with 71 (74) being Staphylococcus aureus. 13 (23) laptops yielded 62 (23) MRSA isolates with 6 (6) being cefotaxime resistant. Sampling after disinfection produced 90 (90) isolates of which 35 (59) were S. aureus. 8 (35) laptops produced 17 (36) MRSA isolates of which 0 (2) were cefotaxime resistant. Conclusion: Results indicate the presence of MRSA on student laptops and that five daily disinfection procedures were more effective than three weekly disinfection procedures. However, more frequent disinfection in addition to other measures appear necessary to achieve laptops free of MRSA.