CASE HISTORY
Tina,a 33-year-old store clerk from Peoria,Illinois,had her first dental exam in five years.She told the hygienist that her gums hurt and that stains appeared on her pillow where her jaw had rested.She also told the hygienist that she did not smoke or drink.
The hygienist found that Tina's gums were swollen and bled upon probing.The gums had receded from Tina's teeth,forming pockets about 5 mm deep,and X-rays revealed some loss of bone.
Tina then saw the dentist,who told her she had periodontitis,inflammatory disease of the gums and bone supporting the teeth.Periodontitis is caused by dental plaque,a biofilm of mixed bacterial species that grow on the teeth.Without regular oral hygiene,the biofilm grows beneath the gum and eventually causes loss of teeth.
Tina expressed surprise,as she thought that only elderly people suffered gum disease.The dentist asked her again whether she smoked,perhaps two packs a day.Tina denied smoking that much,but admitted to one pack a day.The dentist told her that smoking is a common factor in early gum disease,as are diabetes and genetic susceptibility.Under predisposing conditions,many different kinds of bacteria can cause gum disease.
To determine the bacterial species causing Tina's periodontitis,the dentist ordered a DNA test.The DNA test works by polymerase chain reaction (PCR),a technique in which a short piece of DNA is amplified (copied many times),making it possible to read the sequence of DNA base pairs.The DNA sequence reveals the bacterial species.Tina's DNA test revealed Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans,two Gram-negative anaerobes that are sensitive to metronidazole and amoxicillin,respectively.
The DNA test enabled the dentist to target the most effective antibiotics for Tina's condition.The dentist also enrolled Tina in a smoking cessation program.
Following amplification of the bacterial DNA from Tina's sample,one of the ways the bacteria involved may be identified is via sequencing of the amplified fragment of DNA.Explain how this process works and how it can be used to identify bacteria.

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The Answer of CASE HISTORY
Tina,a 33-year-old store clerk from Peoria,Illinois,had her first dental exam in five years.She told the hygienist that her gums hurt and that stains appeared on her pillow where her jaw had rested.She also told the hygienist that she did not smoke or drink.
The hygienist found that Tina's gums were swollen and bled upon probing.The gums had receded from Tina's teeth,forming pockets about 5 mm deep,and X-rays revealed some loss of bone.
Tina then saw the dentist,who told her she had periodontitis,inflammatory disease of the gums and bone supporting the teeth.Periodontitis is caused by dental plaque,a biofilm of mixed bacterial species that grow on the teeth.Without regular oral hygiene,the biofilm grows beneath the gum and eventually causes loss of teeth.
Tina expressed surprise,as she thought that only elderly people suffered gum disease.The dentist asked her again whether she smoked,perhaps two packs a day.Tina denied smoking that much,but admitted to one pack a day.The dentist told her that smoking is a common factor in early gum disease,as are diabetes and genetic susceptibility.Under predisposing conditions,many different kinds of bacteria can cause gum disease.
To determine the bacterial species causing Tina's periodontitis,the dentist ordered a DNA test.The DNA test works by polymerase chain reaction (PCR),a technique in which a short piece of DNA is amplified (copied many times),making it possible to read the sequence of DNA base pairs.The DNA sequence reveals the bacterial species.Tina's DNA test revealed Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans,two Gram-negative anaerobes that are sensitive to metronidazole and amoxicillin,respectively.
The DNA test enabled the dentist to target the most effective antibiotics for Tina's condition.The dentist also enrolled Tina in a smoking cessation program.
Following amplification of the bacterial DNA from Tina's sample,one of the ways the bacteria involved may be identified is via sequencing of the amplified fragment of DNA.Explain how this process works and how it can be used to identify bacteria.

CASE HISTORY Tina,a 33-Year-Old Store Clerk from Peoria,Illinois,had Her First Dental Exam