Occurrence and Evaluation of Antimicrobial Susceptibility of Staphylococcus aureus Isolated from Chicken Eggs, Eastern Ethiopia

Abstract

A total of 335 egg samples were obtained from open market (n = 174) and poultry farm (n = 161) to isolate Staphylococcus aureus present on eggs, and determine antimicrobial susceptibility patterns. A sterile cotton swab was used to sample the surface of eggs. After sterilizing the shells, the egg contents were sampled. Isolation of Staphylococcus aureus was done based on culture characteristics, Gram staining and biochemical tests. The isolates were subjected to antimicrobial susceptibility testing using disc diffusion method. Out of the total 335 eggs sample examined, 93(27.8%) samples yielded S. aureus. Out of these, 28(17.4%) were from poultry farm while 65(37.4%) were obtained from open market. Similarly, 63(18.8%) were from the shell while 30(8.9%) were from the content. The occurrence of S. aureus in the egg shell collected from open market was significantly higher than egg shell obtained from poultry farm (P = 0.021). The level of S. aureus in egg contents was also significantly higher in the open market (P = 0.003). All 76 S. aureus isolates were resistant to at least one of the antimicrobials tested with overall 3.9-92.0% level of resistance pattern showing higher resistant to penicillin (92%), ampicillin (89.5%) and amoxicillin (55.3%). Multiple drug resistance to more than two antimicrobial agents was detected in 86.8% of the total S. aureus isolates. The study showed high level of S. aureus with considerable antimicrobial resistant pattern. Further study is needed to better define bacterial resistance to antimicrobial agents with emphasis on surveillance of multiple drug resistant.