Developing a Vaccine for Clostridium Difficile
Clostridium difficile (C. difficile) bacteria is one of the primary sources of sepsis, which is a life-threatening complication of an infection. C. Difficile infections mainly occur in patients over in hospitals over the age of 65 and typically occurs after the use of antibiotics. After a patient has taken antibiotics to stop the growth of the bacteria causing their primary infection, most of the beneficial bacteria that reside in the intestines are wiped out as well. C. difficile is then able to colonize the intestines and spread throughout the rest of the body. Hence, C. difficile typically causes secondary infections, an infection that occurs during or after the treatment of another infection.
Symptoms of a severe C. difficile infection include watery diarrhea, abdominal cramping and pain, fever, weight loss, kidney failure, intestinal inflammation, and toxic megacolon, all eventually leading to sepsis. Every year, over 500,000 people in the US are infected by C. difficile, with numbers rising in recent years. C. difficile is particularly difficult to completely wipe out because it can form endospores that can keep the bacteria alive for hundreds of years. Endospores are a dormant form of the bacteria that are produced once living conditions are no longer suitable. Endospores are more resistant to stress factors and can survive where C. difficile normally would not be able to. Once an endospore finds an environment with the appropriate conditions, it can germinate and become a viable cell once again and colonize the new environment.
Symptoms of a severe C. difficile infection include watery diarrhea, abdominal cramping and pain, fever, weight loss, kidney failure, intestinal inflammation, and toxic megacolon, all eventually leading to sepsis. Every year, over 500,000 people in the US are infected by C. difficile, with numbers rising in recent years. C. difficile is particularly difficult to completely wipe out because it can form endospores that can keep the bacteria alive for hundreds of years. Endospores are a dormant form of the bacteria that are produced once living conditions are no longer suitable. Endospores are more resistant to stress factors and can survive where C. difficile normally would not be able to. Once an endospore finds an environment with the appropriate conditions, it can germinate and become a viable cell once again and colonize the new environment.
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Currently, vaccines that would help prevent the infection of C. difficile are being tested, and phase II trials, which focuses on its effectiveness, have recently been completed. This vaccine contains genetically and chemically weakened versions of toxins A and B, toxins produced by C. difficile that normally would disrupt human cell structure, ultimately causing cell death. By injecting the weakened versions of these toxins as a vaccine, the human immune system will be able to produce antibodies to these toxins without actually causing an infection to the test subject. The phase II trials included 885 healthy adults between the ages of 65 and 85, as that is the age range in which C. difficile infections are most common. The test subjects received either 0, 100, or 200 micrograms of the vaccine on either the ‘daily regimen’ or ‘monthly regimen’. For the ‘daily regimen’, patients received the vaccine on the 1st, 8th, and 30th day for the 6 month duration of the trial. For the ‘monthly regimen’, patients received received the vaccine on the first day, then at the 1st month and 6th month of the trial. The trials found the highest immune response among the patients that received the 200 microgram dose and were on the monthly regimen. Because of the positive results seen during the phase II trial, a phase III trial is planned. The phase III trial will consider the effectiveness of the vaccine among adults aged 50 years or older who have an increased risk for CDI due to age and increased exposure to healthcare systems.
As a major cause of secondary infection in hospitalized patients, C. difficile remains one of the most dangerous bacteria and requires intensive treatment. Furthermore the presence of endospores allows this bacteria to lie dormant until it comes across an ideal environment in which it can proliferate. While researchers have created a vaccine to help prevent C. difficile infections, this vaccine is not yet available to the public. FDA approval of this vaccine would be extremely beneficial to those at risk of contracting this infection and would drastically decrease the amount of secondary infections that occur in hospital settings.
As a major cause of secondary infection in hospitalized patients, C. difficile remains one of the most dangerous bacteria and requires intensive treatment. Furthermore the presence of endospores allows this bacteria to lie dormant until it comes across an ideal environment in which it can proliferate. While researchers have created a vaccine to help prevent C. difficile infections, this vaccine is not yet available to the public. FDA approval of this vaccine would be extremely beneficial to those at risk of contracting this infection and would drastically decrease the amount of secondary infections that occur in hospital settings.
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