Identification and antimicrobial resistance pattern of Staphylococci isolated from cottage cheese (ayib) and yoghurt (ergo) in selected districts of jimma zone, Ethiopia

Abstract

Staphylococci are the main cause of food borne intoxication and food borne outbreaks worldwide due to its ubiquity and ability to persist and grow under various conditions. A crosssectional study was carried out between the periods of May 2014 to March 2015 with the aims to investigate the occurrence of Staphylococcus, determine the prevalence of Staphylococcus and evaluate the antimicrobial resistance pattern of the isolates from cottage cheese (Ayib) and yoghurt (Ergo) collected from selected districts of Jimma Zone, Ethiopia. Identification of the staphylococci was undertaken using Gram's staining, catalase, sugar fermentation and coagulase tests on 400 samples (cottage cheese = 200, yoghurt = 200) collected by simple random sampling technique. The overall prevalence of Staphylococcus in this study was found to be 14.3% with a specific prevalence of 22% in cottage cheese and 6.5% in yoghurt. The difference on the prevalence of staphylococci between cottage cheese and yoghurt was found to be statistically significant (P<0.05). Four species of staphylococci were identified and their prevalence was confirmed to be 5%, 3.5%, 3.3% and 5.8% for S. aureus, S. intermedius, S. hyicus and coagulase negative staphylococci respectively. The specific prevalences in cheese and yoghurt for each species respectively were 7% and 3% (S.aureus), 5.5% and 1.5% (S. intermedius), 4% and 2.5% (S. hyicus), and 9.5% and 2% (coagulase negative staphylococci). The identification results showed that the contamination of cottage cheese with staphylococcus was more likely to occur than yoghurt (OR = 4.1, 95%CI = 2.1-7.8). The disc diffusion assay of 70 isolates against five biogram revealed the highest resistance to penicillin G (65.7%) followed by tetracycline (41.4%), streptomycin (37.1%), gentamycin (35.7%) and kanamycin (28.6%). A large proportion of the isolates (87.1%) were resistant to one or more antimicrobials. The staphylococci found in cottage cheese and yoghurt was could be due to traditional methods of milking, handling, preparing, storing, selling and hygienic status of the personnel. The high antimicrobial resistance of the staphylococcal isolate observed might be due to indiscriminate use of the drug at the study area. Hence, sanitary measures and awareness creations are needed to improve the hygienic conditions of cheese and yoghurt from farm-to-table continuum as well as proper use of antimicrobials in order to guarantee the health and quality of these highly popular products.