Bacteria...?

Question

When bacteria are grown under adverse conditions, i.e. in the presence of a poisonsuch as an antibiotic, most cells grow slowly. But it is not uncommon that the growth rate of a bacterial culture kept in the presence of the poison is restored after a few days to that observed in its absence. Suggest why this may be the case.

Answer 1

At least on Earth, life is a hardy organism and it tries to grow anywhere it can find water; from just under the ice in the deserts of Antarctica to the undersea volcano vents. Evolution lets those bacteria survive the poison and grow.

One of the hardest creatures is bacteria; they are small, can get into almost anything, and they can exist and breed free floating in the water or in the atmosphere. Some strains grow in the presence of oxygen (salmonella) or without oxygen (botchulism). We are starting to find really harder versions that can survive exposure to antibiotics.

When an antibiotic is administered it secrets a poison that kills some bacteria, the first one discovered was penicillin (of course). Since then our arsenal has only grown. Since they can be given with a simple shot or just a pill, and have few problem side effects, they are a very popular treatment; too popular. Many people ask for antibiotics even when they have a viral infection. In the past the doctors agreed thinking that the antibiotics wouldn’t hurt. If the patient took them then they would fight most bacterial infections letting the body concentrate on the viral infection. They also would have a placebo effect, if the patient felt like he was doing something to cure his infection then that could boost the body’s immune response and help fight the infection. The power of positive thinking can be very strong and doctors know this; they have seen patients with the same illness heal at different rates. Almost always the person with the positive attitude heals faster, or just survives longer than other patients with a worse attitude.

This over use of antibiotics has resulted in creating stronger strains. When an antibiotic is used some of the bacteria survives it. Usually the rest of the bacteria are taken out by the bodies’ normal immune system, but not always. This is an example of evolution in action. The bacteria that was susceptible to the antibiotic dies quickly, and don’t get the chance to reproduce. The bacteria that do survive are stronger. These stronger bacteria breed and pass on their genes making a stronger and stronger strain of bacteria. The continued expose of antibiotics to these strains of bacteria breed more robust strains, because those are the only strains that survive. Finally the bacteria become immune to that antibiotic.

The problem becomes worse if the patient starts to feel better and decide to not finish taking the antibiotics. Why not, they feel better and their body has the situation under control? This means more strains of stronger bacteria get a chance to survive. Some of the bacteria that could have been killed by the antibiotics also will survive, but only those that could have survived for a longer time that the others will live long enough to breed. The bacteria can breed and cross two successful gene patterns that can survive that antibiotic, making the bacteria even more robust.

When these immune bacteria are excreted by the body, breathed out, or pass out in some other fashion they breed. When this happens the chance of being exposed to a stronger and stronger bacteria strain increases, which just allows that strain to breed even more and continue to get stronger (in it’s immunity to that antibiotic).

So when a person gets infected with a really hardy strain of bacteria (that is immune one or more antibiotics) the typical antibiotics have no affect. So another antibiotic is used, and if it doesn’t kill ALL of that strain of bacteria then bacteria develop that are immune to yet one more type of antibiotic.

This is a serious problem so doctors have reserved some antibiotics to only be used in case of a really immune strain. If this continues then we can run out of effective antibiotics. Remember we are trying to kill the bacteria not the patient, so the types of antibiotics we can use are limited. As we improve out knowledge about genes we can create a virus that is targeted only to that bacteria. The problem with that is that bacteria have short life spans and breed very quickly. So they go through several generations quickly, and they change slightly with each generation. Therefore a virus targeted to hit a specific bacteria strain this year, may not be able to hit that same strain next year. We see this problem with the flu virus, and have to make a new vaccine for the flu every season. Viruses don’t have enough material to breed by themselves. They can only breed in a host, by hijacking some of the host’s cells. Bacteria don’t have this problem; they can happily breed on their own as long as they have a growth medium (food).

The problem only gets worse in a hospital. There are a lot of sick people giving off bacteria, suffering from bacterial infections and so on. This makes the hospital a soup of bacteria. Since the use of antibiotics in hospitals is common, we have the greatest chance to get a strain that can survive an antibiotic in the hospital. This is why infection after the surgery is a big threat, and with more robust strains of bacteria the threat will only grow.

If you breed bacteria in a container that has something that can kill them, it may not kill all of them. Those that don’t die, those with an immunity to that poison, continue to breed—survival of the fittest. With quick generations and a strong evolutionary pressure (the poison) soon the bacteria develops a strain that can survive that poison and it starts to breed Before long the only bacteria that you have left are those that are immune to that poison. If you were to take the surviving bacteria and expose it to a new, not quite fatal, poison then you would get a strain of bacteria that is immune to both poisons. This will continue until you end up with a Super Bug.

Like I said this is an example of evolution in action. The poison will kill most of the bacteria, but not all, and those that survive will continue to multiple and the colony grows.

Answer 2

bacterias are micro scopic unicellular organisms . They can produce a hard outer covering which is resistant to any conditions .

during this period the growth rate is slow and it prepares for a sudden growth by storing the energy to be used in the mitochondria and when the effect of the anti biotics are over the it would remove its outer covering and its growth rate will be fast and it would catch up with its normal growth or even faster .

Answer 3

The bacteria are numerous. Out of the gillions of cells a few are resistant to foreign environment. All other bacteria die, but the small number of resistant bacteria take time to reproduce to original numbers.

Answer 4

1

Answer 5

What a cheater! Read your textbook for the answer.