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Risk Assessment and Management of Escherichia Coli in Local Vegetable Markets

Thesis Info

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Author

Sadia Alam

Program

PhD

Institute

Quaid-I-Azam University

City

Islamabad

Province

Islamabad.

Country

Pakistan

Thesis Completing Year

2011

Thesis Completion Status

Completed

Subject

Natural Sciences

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/2461/1/3044S.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676727106022

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Fresh produce linked foodborne outbreaks have become a global concern. Nutritional value of vegetables and high prices of meat and meat originated food compel common people for consumption of plant originated food particularly salad vegetables. Microbial population of vegetable surfaces contains large number of pathogenic bacteria including members of Enterobactereace. Most promising pathogen among enteric microbes is Escherichia coli (E.coli) that is normally a nonpathogenic bacteria and becomes virulent due to several pathogenic factors like toxin production. Shigalike toxins are chief disease causing molecular structures produced by Shigalike toxin producing strains of E.coli possessing genes for shigalike toxin I and shigalike toxin II. It was intended to assess and manage the risk associated with these potential pathogens. This research was an effort to reduce faecal contamination of salad vegetables consumed in Pakistan and to provide clean nutritious food to public. A survey was conducted in three markets of Islamabad, Rawalpindi and Lahore and tomato, lettuce, cabbage and cucumber were collected from three shops of each market. Each vegetable was analysed as unwashed and washed for aeobic plate count (APC), total coliforms, faecal coliforms and E.coli. About two hundred and fifty E. coli isolates were preserved, serotyped and studied for presence of shigalike toxin genes. Results indicated a high APC on all vegetable samples. Total coliforms, faecal coliforms and E.coli count exceeded the permissible limits in most samples. Highest APC was associated with lettuce (6.6 log 10 cfu/g). Tomato was least contaminated by APC (5.6 log 10 cfu/g). E.coli was detected in tomato, lettuce, cucumber and cabbage. Washed samples showed significantly reduced bacterial population. Two hundred and fifty isolates of E.coli were biochemically characterized and serotyped for O and H antigens. Majority of strains could not be identified by serotyping. Polymerase chain reaction (PCR) results indicated presence of shigalike toxins in 55 E.coli isolates. Raw garlic proved to be most promising antibacterial spice extract with maximum zone of inhibition (29mm) and lowest MIC (3mg/ml). Ginger, cinnamon, mustard also indicated considerable antibacterial activity. Extracts xiprepared by using methanol, acetone and water as solvents showed variable antimicrobial efficiency. Solvent extraction reduced efficacy of extracts as compared to crude extracts. Acetic acid, citric acid and common salt also lowered growth of E.coli strains. A treatment solution of pH=2.7, consisting of 5 ml of raw extracts of garlic, ginger, mustard, cinnamon, 5 ml of 2% acetic acid, 2% citric acid and 1.5% common salt was prepared and directly applied on salad vegetables. This composite treatment solution significantly reduced APC and completely eliminated total coliforms, faecal coliforms and E.coli. These findings conclude with high potentially pathogenic microbial load on salad vegetables and urge for preventive action on priority basis. Raw spice extracts alongwith non toxic chemicals provide an excellent source for pathogens elimination from fresh produce.
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آزاد

  آزاد

سکندر عباسی

لوگ اسے مینٹل کیس کہہ کر بلاتے تھے۔، کیونکہ اس کا مزاج کسی سے بھی نھیں ملتا تھا۔ وہ بھیڑ میں بھی تنھا رہتا تھا۔ اس کی عادتیں عجیب تھیں۔ اس کی سوچ سماجی سانچے میں ڈھل نھیں پاتی تھی۔ اس کے خیالات بنا پروں کے پرواز رکھتے تھے۔ اس کا طرز حیات عام دنیا سے ہٹ کے تھا۔ دنیا سے باغی دماغ میں وہ انیک سوالوں کے انبار لیٸے پھرتا تھا۔ اس کی سوچوں کے سمندر میں الجھے الجھے سوالات سیپیوں کی مانند چمکتے رہتے تھے جو اسے ہمہ وقت بے سکون رکھتے تھے۔ گھر والوں نے اس کا نام تو کچھ اور ہی رکھا تھا مگر وہ خود کو آزاد کہلواتا تھا۔ یہ ہی وجہ تھی کہ وہ آزاد کے نام سے بدنام تھا کیونکہ لوگ اس کا ذکر مضحکہ خیز انداز میں کرتے تھے۔

آزاد کو بے ترتیبی سے عشق تھا جسکو وہ اپنے لیٸے آ کسیجن گردانتا تھا۔ اس کو خوف تھا کہ اگر یہ بے ترتیبی اس کی زندگی سے بیدخل ہوٸی تو اس کا کی سانسوں کی ڈور ٹوٹ جاٸیگی۔ اسی باعث آزاد کی حیات کا ہر ایک صفحہ بے ترتیب اور بکھرا ہوا تھا۔ اس کے خواب بلکل ایسے معصوم تھے جیسے پرندوں کے خواب ہوتے ہیں۔ وہ قید سے کتراتا تھا، غلامی سے اسے سخت نفرت تھی ، پابندیاں اس کو پسند نھیں تھیں .

آزاد کبھی بھی استری کئے ہوئے  کپڑے نھیں پہنتا تھا ، شکن آلود کپڑے اسے زندگی کی علامت محسوس ہوتے تھے۔ وہ کبھی بالوں کو کنگھی نھیں کرتا تھا اس کے خشک اور بکھرے ہوٸے بال اس کے خیالوں کی طرح ہر قید و بند آزاد تھے۔جدید زمانے میں بھی اس کے پاس موباٸیل فون نھیں...

توریہ کے اصطلاحی مفاہیم اور اس کی شرعی حیثیت

Twriyah in a speech or word contains multiple meanings having different interpretations of its primary meaning. This article represents the linguistic and connotative concept of Twriyah and T’ryd in the light of Qur’an, hadith, Sirat, the views of various jurists. By analytical study of the available literature it is concluded that there is difference between using Twriyah and Falsification. There are several rules which regulate the use of Twriyah in special circumstances. All Messengers of Allah have never give false statements in any case, however they often used Twriyah in their statements. This article elaborated the various meanings and situations of Twryh in the light of Islamic teachings.

Anthraquinone Sulfonamides and Derived Heterocycles: Design, Synthesis, Biological Evaluation and Computational Studies

Leishmaniasis, a worldwide prevalent disease, is still enjoying the ruling with no proper medication; and to add to this current gloomy scenario the disease causing parasite Leishmania is becoming resistant to the ongoing medication that is being practiced now a days. Hence, the need is to search for reasonable, safe and targeted drugs; the present research is one such effort in this direction. To begin with, Leishmanolysin (GP63), zinc metalloprotease, expressed over the surface of Leishmania species was selected as drug target due to its virulence and reason for parasite resistance. A library of benzimidazole derivatives (1-37) was synthesized and screened for its antileishmanial potential against L. major. All the compounds were found potent antileishmanial with IC50 values in the range of 0.62-0.92 μg/mL as compared to amphotericin B (standard drug) IC50 value 0.56 μg/mL. 2-(Thiophen-2-yl)-1H- benzimidazole (19) and 2-(1H-indol-3-yl)-5-nitro-1H-benzimidazole (34) were identified as the lead compounds of the library with IC50 value of 0.62 μg/mL. ADMET properties of the entire library were also predicted by using ADMET PredictorTM and were observed to be safe. Molecular docking studies carried out on all the members of library and amphotericin B by using MOE software, indicated that the most active compounds fitted at the centre of binding pocket of GP63 built by amino acid residue His264, His268, His334 and Zn578. On the basis of molecular docking results, receptor based pharmacophore model was built containing three Aro|Hyd features and one Acc&ML feature. This pharmacophore model was used to design new scaffolds for antileishmanial compounds. Four libraries, 2-(2- aryl/heteroarylbenzimidazol-1-sulfonyl)anthraquinones (38-69), N-(heteroaryl)-anthraquinon-2- sulfonamides (70-95), aryl anthraquinon-2-sulfonates (96-111) and N-(anthraquinon-2-sulfonyl)-amino acid methylesters (112-123) were designed and all the cmpounds were found as hit by pharamocophoric search. Their antleishmanial activities were predicted by QSAR model; built by MOE software by selection of 94 descriptors and partial least square (PLS) method on experimental antileishmanial activity of 37-mebered library and amphotericin B, validated by internal and exernal test sets with correlation coefficient (R2) 0.7762. All the compounds belonging to four libraries (38-69, 70-95, 96-111 and 112- 123) were found potent antileihmanial with predicted activity in the range of 0.5435-0.9940. All the compouds were observed safe according to predicted ADMET properties and Lipinski’s rule of five (Ro5). Later, these four designed libraries were synthesized and characterized by physical constants and spectroscopic techniques for onward screening for their antileishmanial potential against L. major by using amphotericin B as standard control which confirmed that all the compounds were potent antileishmanial. Compliance of the predicted activity by QSAR model with observed activity from in vitro antileishmanial activity resulted in identification of the same lead compounds in each library 38-69, 70-95, 96-111 and 112-123 i.e. 2-(5-Nitro-4-methoxyphenyl-1H-benzimidazol-1-sulfonyl)anthraquinone (61) (predicted activity 0.6794, IC50 0.67 μg/mL), 2-(1H-benzo-1,2,3-triazol-1-sulfonyl)anthraquinone (91) (predicted activity 0.5579, IC50 0.57 μg/mL), 2-(1H-pyrazol-1-sulfonyl)anthraquinone (90) (predicted activity 0.5435, IC50 0.58 μg/mL), benzyl anthraquinon-2-sulfonate (100) (predicted activity 0.7615, IC50 0.76 μg/mL) and N-(anthraquinon-2-sulfonyl)-2-phenylglycine methylester (123) (predicted activity 0.7305, IC50 0.75 μg/mL). Pharmacophore based molecular docking studies carried out on all the eighty six compounds on GP63 by MOE software showed hydrophobic interactions, hydrogen bonding and metal ligation interactions with His268, His264, His334 and Zn578, respectively. This entire set of experiments in both dry and wet labs led to a successful designing of a variety of anthraquinon-2- sulfonamides as a novel scaffold having strong antileishmanial effect.