University of Khartoum

Prevalence, Antibiotic Resistance and Plasmid Profile Patterns of Staphylococcus Isolates Recovered from White Cheese Samples Collected from Retail Markets in Khartoum State

Prevalence, Antibiotic Resistance and Plasmid Profile Patterns of Staphylococcus Isolates Recovered from White Cheese Samples Collected from Retail Markets in Khartoum State

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Title: Prevalence, Antibiotic Resistance and Plasmid Profile Patterns of Staphylococcus Isolates Recovered from White Cheese Samples Collected from Retail Markets in Khartoum State
Author: Ali, Nahla Mohammed Ahmed
Abstract: The objective of this study was to determine the prevalence, antibiotic resistance pattern and plasmid profile of Staphylococcus isolates recovered from white cheeses collected from different groceries in Khartoum State. A total of 120 cheese samples were collected, cut into pieces and immersed into peptone water for 72 hrs at 37°C. One ml cheese suspension was then transferred to plates of Staphylococcus Agar medium No.110 and incubated at 37°C for 48 hrs. Typical Staphylococcus colonies were picked, repeatedly subcultured for further purification and preserved in Nutrient Agar slants. Tentative Staphylococcus isolates were characterized by cultural, microscopic, biochemical and molecular means using standard methods. The antibiotic susceptibility of the isolates was tested against 12 antibiotics by Kerby Bauer, s method and plasmid profile of each isolate was also determined. Fifty (41.75%) Staphylococcus isolates were recovered from the cheese samples. Of these, 35 (70%) were identified as S.aureus as they have shown yellow colonies on Mannitol Salt Agar (MSA) medium, expressed coagulase enzyme and produced the target (108 bp) PCR amplicon of a known S.aureus 16S RNA conserved region. The remaining (30%) were identified as S. epidermidis. Results of antibiotic susceptibility testing indicated that resistance was most common to ampicillin and gentamycin (each 98%) followed by cefotaxime (90%), cloxacillin (84%), cephalexin (82%), tetracycline (68%), linomycin (52%), roxithromycin (34%), linezolid, (30%), co-trimoxazole (18%), ciprofloxacin (16%) and levofloxacin (14%). Over 85% of the isolates showed multidrug resistance phenotype with multiple antibiotic resistance indices (MARI) of > 0.2. Thirtyـــone different multidrug resistance profiles were identified among the 50 tested isolates. The most common (80%) resistance profiles were those which included resistance to ampicillin, cephalexin and tetracycline. Three of the isolates were resistant to ten out of the 12 tested antibiotics. Four different plasmid profile types each consisting 1 ـــ3 different plasmids with 1.3, 1.8 or 3.0 kb size were detected among 33 of the tested Staphylococcus isolates. No plasmid has been detected in 17of the isolates although they showed multidrug resistance phenotypes with 0.33ــ0.83 MARI. Likewise, no consistent relationship has been detected between plasmid profiling and antibiotic resistance phenotypes. This study indicates the prevalence of multidrug resistant Staphylococcus isolates in white cheeses consumed in Khartoum State. A comprehensive hygiene practice should be adopted in production of milk and milk products
URI: http://khartoumspace.uofk.edu/123456789/25608


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