الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Dental caries is a widespread, persistent, but non-communicable disease worldwide. It is caused by a group of microorganisms, including bacteria, yeast, and fungi. As they are the main factors that cause sensitivity and tooth decay.
The objectives of this study included isolating, characterizing and identifying the most common dental caries-causing bacterial isolates and the use of culture methods and the morphological and biochemical properties of these isolates and the application of several different methods to overcome these bacterial species , One of these methods is to test the sensitivity of different antibiotics on the bacterial species that cause tooth decay , Some alternative methods of antibiotics resistant to pathogenic bacteria have also been applied and used to find out their efficiency against these isolates. Among these methods is the use of probiotics for different species, as well as the use of chemical alternatives, such as mouthwash, which contains chlorhexidine, which is effective against different bacterial species.
The results can be summarized in the following points:
1- 60 bacterial isolates were collected from different sources, as they were collected from Benha University Hospital, dental outpatient clinics, and the Health Insurance Hospital in Qalyubia Governorate. These swabs were collected using sterile cotton swabs then cultivated on TSA blood agar environment in the microbiology laboratory of the Botany Department.
2- 13 bacterial isolates were tested by dishes on the solid media, and 3 isolates were chosen from among the 13 studied bacterial isolates, as they gave white dots in the solid media. Then those isolates were examined by culture methods on a specialized media like TSA blood agar and to find out the most important characteristics of each isolate, and it was found that the 3 isolates in the dishes gave a different analysis of the blood environment, one of which was an analysis of the alpha haemolysis, the second a beta type, and the third a gamma one. With Branched spherical or cluster chains.
3- The bacterial isolates (ME01, STM01, EF01) were identified based on the phenotypic characteristics, according to Bergas Manuel, as Staphylococcus aureas ME01, Streptococcus mutans STM01, Enterococcus faecalis EF01), respectively. The definition of the bacterial isolates was confirmed by studying the biochemical characteristics of each of them, where it was found that one of the three isolates S. aureus was catalase positive and coagulase positive noticed by bubbles of H2O2 on the slide while S. mutans and E. faecalis were coagulase negative, since no bubbles occurred on the slide, and no aggregation and clotting occurred during the coagulase test.
4- Different antibiotics were used to find out the effect of each antibiotic on different bacterial species, where 19 antibiotics were applied to each type, including Erythromythin, methicillin, cefotaxime, Nitrofurantoin, Amoxicillin, penicillin G, Chloramphenicol, vancomycin, where the isolation of S. aureas showed ME01 has resistance against many antibiotics with different percentages, about 80% against Erythromythin, methicillin, cefotaxime, Nitrofurantoin, 100% resistance to Amoxicillin, penicillin G, while it showed resistance by 60% to Chloramphenicol and 30% to vancomycin. Isolate S. mutans STM01 showed 100% resistance to some of these antibiotics to Erythromythin, methicillin, cefotaxime, penicillin G, 50% to Chloramphenicol and 100% sensitivity to other antibiotics, including vancomycin, and isolate E. faecalis EF01 showed 100% resistance to most antibiotics. They are Erythromythin, methicillin, cefotaxime, penicillin G, chloramphenicol, and 100% sensitivity to amoxicillin, vancomycin, and nitrofurantoin.
5- To overcome the problem of bacterial isolates resistance to most antibiotics, different types of probiotics have been used and applied, such as lactobacillus acidophilus EMCC1324(La), Bifidobacterium bifidum (Tissier 1900) EMCC 1334(Bb), Enterococcus faecalis ATCC 19433, Lactobacillus plantarum EMCC 1027(Lp). , Lactobacillus rhamnosus EMCC 1105(Lr), Bacillus subtilis MBG874, where most of the different types of probiotics showed effectiveness and efficiency to inhibit the growth of bacterial isolates, especially the two types of lactobacillus acidophilus EMCC1324(La), Bifidobacterium bifidum (Tissier 1900) EMCC 1334(Bb). the inhibation zone for probiotics EMCC1324(La) was measured for each isolate and was 15.5mm for S.aureus isolate, 15mm for S. mutans isolate, 13mm for E. faecalis isolate, while the probiotic Bifidobacterium bifidum (Tissier 1900) EMCC 1334(Bb) was the inhibation zone for the first isolate. 14mm, the second isolation 12.5mm, and the third isolation 13mm.
6- The use of different probiotics to inhibit the growth of bacterial isolates resistant to most antibiotics had an effect in overcoming the bacteria that cause tooth decay, and it was compared with the use of some of the chemicals currently used as mouthwash to get rid of caries bacteria, where a mouthwash containing chlorhexidine was used and a study inhibation zone and compared with probiotics. It was found that mouthwash (chlorohexidine 125mg) gave the highest zone for the first isolate, S. aureus, where it was 22 mm, followed by the second isolate, S. mutans, 19 mm, and the third isolate, E. faecalis, 17.5 mm.
7- Through these results, it was clarified that lack of oral hygiene and the use of antibiotics are among the most predisposing factors for tooth decay, and that there are alternative ways to overcome the problem of antibiotic resistance, which is the use of probiotics and mouthwashes.