Microbial evaluation of boiled eggs sold in retail outlets in Zaria, Nigeria

Abstract

One hundred and fifty samples of boiled eggs were collected from three designated sampling areas in Zaria, Nigeria, for the isolation of Escherichia coli and Staphylococcus aureus, widely known to be contaminants and in some cases pathogens in ready-to-eat foods. Total aerobic plate count was carried out using nutrient agar. The total aerobic plate count ranged from 1.0 x 109 to 7.1 x 1010 cfu/g. The average aerobic plate count was 1.8 x 1010 cfu/g. The samples were inoculated on Eosin Methylene Blue (EMB) and staphylococcus 110 agars and the susceptible isolates were subjected to standard biochemical tests and pathogenicity tests for proper biochemical characterization and identification of the pathogens respectively. The results showed that out of 7 suspected isolates of Escherichia coli and 9 of the suspected Staphylococcus aureus isolates, there were no Escherichia coli confirmed in all 7 (100%) isolates and 9(100%) was confirmed as Staphylococcus aureus. Therefore, the work shows that boiled eggs can be contaminated and that unsanitary, and unhygienic practices, during preparation and presentation especially cracked shell eggs for consumption can pose serious health hazards.