Abstract :Elderly residents of nursing homes are more susceptible to bacterial infections when compared to
young adults, mostly by commensal bacteria from microbiota, such as staphylococci. This study
aimed to isolate S. aureus and S. epidermidis from the nasal cavity of elderly residents of a nursing
home in Presidente Prudente, SP, Brazil, to determine their antimicrobial susceptibility and biofilm
production. Swabs were collected from 32 individuals and the S. aureus and S. epidermidis isolates
were tested regarding their antimicrobial susceptibility by the disc diffusion method and agar
screening with oxacillin. Biofilm production was determined by the Congo Red Agar (CRA) method
and adherence to borosilicate test tubes. Forty-one bacterial samples were obtained, corresponding
to 87.8% of staphylococci. S. aureus was isolated from 10 individuals and S. epidermidis from 8.
The isolates were resistant to oxacillin, cefoxitin, erythromycin, levofloxacin and clindamycin, and
100% susceptible to vancomycin and linezolid. Oxacillin resistance was found in 40% of S. aureus
and 62.5% of S. epidermidis isolates. Biofilm production by S. aureus was observed in 90% of strains
by CRA and 80% by the borosilicate test tube. By CRA and borosilicate tube test, respectively, 100%
and 62.5% of S. epidermidis produced biofilm. Our data emphasize the need for prophylactic and
biosecurity measures in order to avoid dissemination of multiresistant and virulent strains in those
environments, a potential cause of elderly infections.