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Detection of enterotoxins genes in staphylococci isolated from milk and cheese
العناوين الأخرى
التحري عن جينات السموم المعوية في المكورات العنقودية المعزولة من الحليب و الجبن
مقدم أطروحة جامعية
al-Khafaji, Marwah Hamid Muṭashshar
مشرف أطروحة جامعية
أعضاء اللجنة
al-Hassani, Hayfa Hadi
Kazim, Shruq R.
Jumah, Intisar M.
Fadil, Iyad Muhammad Ali
Muslih, Rashid Mahjub
الجامعة
جامعة بغداد
الكلية
كلية العلوم
القسم الأكاديمي
قسم علوم الحياة
دولة الجامعة
العراق
الدرجة العلمية
دكتوراه
تاريخ الدرجة العلمية
2013
الملخص الإنجليزي
During 2011; 300 milk and cheese samples were collected from Baghdad markets.
Two hundred staphylococcal isolates were isolated from milk and cheese samples, the predominant species was Staphylococcus aureus, 97 isolates (48%), followed by S.chromogenes 82 isolates (41%) and 21 (11%) S.epidermidis isolates.
The pattern of antibiotic susceptibility of Coagulase Positive Staphylococci (COPS) and Coagulase Negative Staphylococci (CONS) isolates to 3 antibiotics (Methicillin, Tetracycline and Vancomycin) was determined using disc diffusion method; the results revealed that 80 S.
aureus isolates (82.47%) found to be methicillin resistant (MRSA) and 18 S.
aureus isolates (19%) resist tetracycline while 8 isolates (8.24%) were vancomycin resistant (VRSA).
Sixty four CONS isolates (62.13%) were methicillin resistant, 28 CONS isolates (27.18%) resist tetracycline, and 5 CONS isolates (4.85%) were vancomycin resistant.
Deoxyribo nucleic acid (DNA) extraction from staphylococcal isolates and directly from milk and cheese samples was done manually.
The isolates were subjected to Polymerase chain reaction (PCR) technique in a monoplex pattern to amplify coagulase encoding gene: the coa gene; results by this study showed that 76 (78.35%) S.
aureus isolates gave the amplicon size 730 base pair of the coa gene.
The genetic determinants of methicillin resistance femA and mecA genes were amplified using monoplex PCR technique in order to identify methicillin resistant (mecA+) and susceptible (lacking mecA) staphylococci and to differentiate S.
aureus (femA+) from coagulase negative staphylococci (lacking femA).
Ninety six S.
aureus isolates (98.96%) were found to harbour femA gene, it is species specific marker for S.
aureus.
The mecA gene was detected in 91 (93.81%) MRSA isolates, while it was detected in 70 (67%) CONS isolates.
The detection of staphylococcal enterotoxigenicity according to four classical enterotoxins genes which are sea, seb, sec, and sed was performed simultaneously using multiplex PCR assay.
One hundred fifty three staphylococcal isolates (76.5%) found to be enterotoxigenic, 95 S.aureus isolate (62.09%) found to harbor one or more enterotoxin gene.
CONS isolates showed to be enterotoxigenic in this research, they accomplished 37.9% of the total enterotoxigenic strains (58 strains).
The sea gene was the most frequent enterotoxin coding gene among the others tested; sea accomplished 51.85% of the detected enterotoxin genes followed by the sed gene, which constituted 34.73%, and then the seb coding gene by 12.5% while the sec gene was very rare as 0.92%.
The results obtained by this study showed that 102 (66.66%) staphylococcal isolates harboured only one enterotoxin coding gene, while 39 (25.5%) of the isolates possessed two toxin genes, which were mostly sea and sed genes and 12 staphylococcal isolates (7.8%) harboured three toxin coding gene: sea, seb and sed genes.
Suckling mouse bioassay was tested to investigate the staphylococcal enterotoxin biological activity.
Results showed that 131 isolates which constitutes 65.5% of the examined isolates, gave a positive result.
Both COPS and CONS isolates were shown to be enterotoxigenic, COPS represented by S.
aureus species occupied the higher ratio of the enterotoxigenic staphylococci, 86 S.aureus isolates (65.64% of the enterotoxigenic staphylococci) gave the positive ratio of the intestine weight to the body weight which was ≥ 0.083 while 45 CONS isolates (34.35%) were enterotoxin producers.
These toxins were thermostable staphylococcal enterotoxins which gave the same toxic effect after heating to 100°C for 30 minutes.
Comparing the results obtained by multiplex PCR assay detecting four classical enterotoxin coding genes, with those obtained by suckling mouse bioassay concerning the phenotypic expression of enterotoxin coding genes, 153 (76.5%) staphylococcal isolates harboured one or more enterotoxin coding genes, while the suckling mouse bioassay revealed that 131 (65.5%) of those isolates produced detectable amounts of enterotoxins.
التخصصات الرئيسية
الموضوعات
عدد الصفحات
163
قائمة المحتويات
Table of contents.
Abstract.
Abstract in Arabic.
Introduction.
Chapter One : Literature review.
Chapter Two : Materials and methods.
Chapter Three : Results and discussion.
Conclusions and recommendations.
References.
نمط استشهاد جمعية علماء النفس الأمريكية (APA)
al-Khafaji, Marwah Hamid Muṭashshar. (2013). Detection of enterotoxins genes in staphylococci isolated from milk and cheese. (Doctoral dissertations Theses and Dissertations Master). University of Baghdad, Iraq
https://search.emarefa.net/detail/BIM-598836
نمط استشهاد الجمعية الأمريكية للغات الحديثة (MLA)
al-Khafaji, Marwah Hamid Muṭashshar. Detection of enterotoxins genes in staphylococci isolated from milk and cheese. (Doctoral dissertations Theses and Dissertations Master). University of Baghdad. (2013).
https://search.emarefa.net/detail/BIM-598836
نمط استشهاد الجمعية الطبية الأمريكية (AMA)
al-Khafaji, Marwah Hamid Muṭashshar. (2013). Detection of enterotoxins genes in staphylococci isolated from milk and cheese. (Doctoral dissertations Theses and Dissertations Master). University of Baghdad, Iraq
https://search.emarefa.net/detail/BIM-598836
لغة النص
الإنجليزية
نوع البيانات
رسائل جامعية
رقم السجل
BIM-598836
قاعدة معامل التأثير والاستشهادات المرجعية العربي "ارسيف Arcif"
أضخم قاعدة بيانات عربية للاستشهادات المرجعية للمجلات العلمية المحكمة الصادرة في العالم العربي
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