Antibiotics kill only bacteria. Most common colds and sore throats are caused by viruses. Sometimes when you take an antibiotic, the bacteria may be resistant or become resistant. Resistant bacteria aren't killed by the antibiotic.
They continue to cause infection. You should take antibiotics only when you need to. This can happen if you take an antibiotic for a viral infection. Resistant bacteria have made certain infectious diseases harder to treat. These diseases include tuberculosis, pneumonia, and meningitis. Once a certain type of bacteria is resistant to a medicine, it can pass on that resistance to other types of bacteria.
True B. Antibiotics will help you get better from a cold or the flu. Viruses cause most colds and the flu. They also cause most coughs and most sore throats. But certain antiviral medicines can work for the flu. Taking an antibiotic for a cold or the flu will not help you get better faster.
It may also make some bacteria resistant. This also can happen in children. Children often play together and can easily pass resistant bacteria onto others. This makes the problem worse. Your healthcare provider will probably prescribe an antibiotic if you have an ear infection, a chronic sinus infection, strep throat, or a urinary tract infection. Many of these infections are caused by bacteria.
Many antibiotics only work against certain types of bacteria. These antibiotics are called "narrow-spectrum" antibiotics. The other major category of antibiotics is "broad-spectrum. It is very difficult to kill a virus. To cause disease, pathogenic bacteria must gain access into the body. The range of access routes for bacteria includes:. Forgetting to wash your hands after handling pets and animals is another way for germs to be taken in by mouth. Bacteria that cause disease are broadly classified according to their shape.
The four main groups include:. Most bacteria, apart from the cocci variety, move around with the aid of small lashing tails flagella or by whipping their bodies from side to side.
Under the right conditions, a bacterium reproduces by dividing in two. They develop a tough outer coating and await the appropriate change of conditions. These hibernating bacteria are called spores. Spores are harder to kill than active bacteria because of their outer coating. The body reacts to disease-causing bacteria by increasing local blood flow inflammation and sending in cells from the immune system to attack and destroy the bacteria.
Antibodies produced by the immune system attach to the bacteria and help in their destruction. They may also inactivate toxins produced by particular pathogens, for example tetanus and diphtheria. Immunisation is available to prevent many important bacterial diseases such as Hemophilus influenza Type b Hib , tetanus and whooping cough.. A virus is a miniscule pocket of protein that contains genetic material. If you placed a virus next to a bacterium, the virus would be dwarfed.
For example, the polio virus is around 50 times smaller than a Streptococci bacterium, which itself is only 0. The four main types of virus include:. This makes it difficult for antibodies to reach them. Some special immune system cells, called T-lymphocytes, can recognise and kill cells containing viruses, since the surface of infected cells is changed when the virus begins to multiply.
Many viruses, when released from infected cells, will be effectively knocked out by antibodies that have been produced in response to infection or previous immunisation. Antibiotics are useless against viral infections. This is because viruses are so simple that they use their host cells to perform their activities for them. So antiviral drugs work differently to antibiotics, by interfering with the viral enzymes instead. Antiviral drugs are currently only effective against a few viral diseases, such as influenza, herpes, hepatitis B and C and HIV — but research is ongoing.
A naturally occurring protein, called interferon which the body produces to help fight viral infections , can now be produced in the laboratory and is used to treat hepatitis C infections. It is possible to vaccinate against many serious viral infections such as measles, mumps, hepatitis A and hepatitis B.
An aggressive worldwide vaccination campaign, headed by the World Health Organization WHO , managed to wipe out smallpox. However, some viruses — such as those that cause the common cold — are capable of mutating from one person to the next.
Why are there so few antivirals? The answer boils down to biology, and specifically the fact viruses use our own cells to multiply. This makes it hard to kill viruses without killing our own cells in the process.
Bacteria are self-contained life forms that can live independently without a host organism. They are similar to our cells, but also have many features not found in humans.
For example, penicillin is effective because it interferes with the construction of the bacterial cell wall. Cell walls are made of a polymer called peptidoglycan. So antibiotics that prevent bacteria from making peptidoglycan can inhibit bacteria without harming the human taking the medicine. This principle is known as selective toxicity. Unlike bacteria, viruses cannot replicate independently outside a host cell.
There is a debate over whether they are really living organisms at all. To replicate, viruses enter a host cell and hijack its machinery. Once inside, some viruses lie dormant, some replicate slowly and leak from cells over a prolonged period, and others make so many copies that the host cell bursts and dies. The newly replicated virus particles then disperse and infect new host cells. The problem is that if it targets a replication process that is also important to the host cell, it is likely to be toxic to the human host as well.
0コメント