Revista Ciencias de la Salud (Apr 2009)
Variability of Staphylococcus Aureus Carriers on a Medicine Student’s Population
Abstract
This is a longitudinal study performed ina 159 medicine student’s cohort, of fourth andninth study semester, in order to evaluate thevariation of Staphylococcus aureus carriers andits antimicrobial susceptibility on students, beforeand after clinical practice. Clinical sampleswere taken with a swab from the tonsils, pharynxposterior wall, nasal fosses and hands and werecultured in 5% sheep blood and incubated at37oC in aerobic conditions during 48 hours.The identification of Sthaphylococcus aureuswas performed according to the phenotypic andbiochemical test. The antimicrobial susceptibilitywas evaluated by the diffusion disc methodusing the Kirby-Bauer technique, accordingto Clinical and Laboratory Standards Institute(CLSI), with the following antibiotics: Ciprofloxacyn,Vancomycin, Oxacyclin, Cephalotine,Clyndamycin, and Ryphampycin. The averageage of the fourth semester students was 19.1±1,2 years and the female gender was 2/1 morefrequent than the male. The history of infections,allergy, smoke habit, non infectious diseases,surgeries, antibiotic use during the last threemonths and hospitalizations six months beforesampling was analyzed. There was no significantrelationship between previous history analysisand the carrier state incidence (p=0.001 Mc Nemarexact Test). A significant increase of 15,1%for S. aureus carrier state was observed afterthree years of exposure to hospital environmenton ninth semester students, compared to fourthsemester students (p=0.001 Test Mc Nemar);from which 16.4% (p<0.001) was founded inhands, 13.8% in nasal fosses (p=0.0015) and3.2% in pharynx. 35.8% of S. aureus carrierwas persistent: 25.2% in nasal fosses, 4.4% inpharynx and 3.8% in hands. Antimicrobial resistancewas observed in 1.9% of the bacterialstrains isolated from fourth semester students:One to Ciprofloxacyn and two to Clyndamycin.Besides was observed 2.5% of bacterial strainsisolated from ninth semester students: one toCiprofloxacyn, Oxacyclin, Cephalotine andClyndamycin, one to Cephalotine and Oxacyclinand two to Clyndamycin. Finally, MethycylinResistant Sthaphylococcus Aureus (MRSA)strains were isolated from 1.3% of the studiedgroup. This results didn’t show significant differences(p=1.000).
