Occurrence of Multiple Antimicrobial Resistance among Staphylococcus aureus Isolates from Kenyan Milk

Two hundred and sixteen isolates of staphylococcus aureus were obtained from raw milk within different locations in the Rift Valley of Kenya. Their resistance profiles to six families of antimicrobials were evaluated using the plate diffusion method. Resistance to penicillin (72.2 %) was the most frequent followed by trimethoprim + sulfamethazin (59.2 %); tetracycline (57.9 %); erythromycin (21.3 %); chloramphenicol (46.8 %) and methicillin (7.8 %). Multiple resistances, to penicillin and at least two other non - β-lactam classes of antimicrobials, were observed in 76.9 % of isolates. Multiple resistances to more than four antimicrobials were 13.4 % while 1.9 % were susceptible (non resistant) to all six antmicrobials tested. Pearsons ÷2 statistic was determined to be 10.98 and ÷2 , 6 df = 12.59 (at P = 0.05) , under the null hypothesis of no association for the five regions and resistance pattern. It was concluded that while most of the isolates (76.9 %) were multiple resistance to the tested antimicrobials, there was independence (at the 0.05 level of significance) between the sensitivity levels evident and the regions. Key Words: Milk; Staphylococcus aureus; Antimicrobial Resistance; Multiple resistance Journal of Food Technology in Africa Vol.9(1) 2004: 23-25