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Gram negative bacterial cells have an outer membrane that interferes with antibiotics and drug entry into the cell. The bacteria that are resistant to antibiotics are E. coli, salmonella, shigella, and Yersina. The first three affect the GI tract and the second causes the Black Death. These are resistant to penicillin. So ampicillin and streptomycin are used.
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What does gram negative on a serratia marcescens gram stain mean?
Bacteria are gram positive or gram negative. Serratia happens to be a gram negative bacteria. They appear pink on a gram stain. Gram positive bacteria stain to a purple color on a gram stain. We can classify and ID bacteria using their gram stain and shape. Some antibiotics only work on gram negative bacteria and some only work on gram positive bacteria. It helps a doctor know which antibiotic to use.
Why would you want to know if a gram stain is positive or negative?
Gram negative bacteria (pink gram stain) contain no outer cell membrane, while gram positive bacteria (purple gram stain) do contain an outer cell membrane. Gram negative and positive bacteria can respond differently to antibiotics. Many only work on only one of the two bacteria types. A gram stain is also the first step in identifying a bacteria, dividing bacteria into two large and distinct groups.
Why do some antibiotics work better against gram positive then gram negative bacteria?
Part of describing the function of an antibiotic is stating whether it is effective against Gram-positive bacteria, Gram-negative bacteria or both. (There are other aspects such as whether there is effect on aerobic versus anaerobic bacteria (those that can versus cannot survive in the presence of oxygen), but I'll address that some other time).Some antibiotics have broad spectrum activity, being able to kill Gram-positive and Gram-negative bacteria. At first that might seem like a good thing, and indeed it is when you are treating an infection with an unknown bacterium. However, broad spectrum activity is not desirable when you know exactly what bacterium you are trying to eliminate. If possible, it's much better to target treatment more specifically against the offending bacterium for various reasons, such as to reduce the risk of resistance emerging in other bacterial groups.Some antibiotics are narrow spectrum. Some are most effective against Gram-positive or Gram-negative bacteria, with little activity against the other. In general, we want to use an antibiotic of the most narrow spectrum possible.
Why does penicillin not work on all bacteria?
Penicillin comes from an antibiotic made by one microbe that acts only against certain others. Some microbes are just resistant toward the antibiotic and another will have to be used. At times not enough or a dose that is too weak will prevent the antibiotic from working. Some antibiotics will work only on Gram negative or Gram positive bacteria. Some are broad spectrum and will work on both.It just is that penicillin resistant bacteria are not affected by penicillin. These have mutated and evolved to resist penicillin. These are often called "super bugs".
Why do antibiotics not work on all bacteria?
because it doesn't want to, i mean would you really want to work on someones bacteria. didn't think so!
What does gram negative on a serratia marcescens gram stain mean?
Bacteria are gram positive or gram negative. Serratia happens to be a gram negative bacteria. They appear pink on a gram stain. Gram positive bacteria stain to a purple color on a gram stain. We can classify and ID bacteria using their gram stain and shape. Some antibiotics only work on gram negative bacteria and some only work on gram positive bacteria. It helps a doctor know which antibiotic to use.
Why would you want to know if a gram stain is positive or negative?
Gram negative bacteria (pink gram stain) contain no outer cell membrane, while gram positive bacteria (purple gram stain) do contain an outer cell membrane. Gram negative and positive bacteria can respond differently to antibiotics. Many only work on only one of the two bacteria types. A gram stain is also the first step in identifying a bacteria, dividing bacteria into two large and distinct groups.
Why might a gram-negative infection be harder to treat than gram-positive infection?
In short, it's because they have a membrane around their cell wall that both increases their toxicity, and makes them more resistant to antibiotics. It makes them more resistant because many antibiotics, such as penicillin, work by destroying the cell walls of bacteria. Because they have an extra membrane around their cell walls, gram negative bacteria have extra protection against the antibiotics.
What is the action of antibiotics used to treat Gram negative bacterial infections?
Most work by inhibiting cell wall biosynthesis in the bacteria.
Why are broad-spectrum antibotics often used to treat infections caused by unidentified pathogens?
Broad-spectrum antibiotics are used to treat unidentified pathogens because they are active again gram positive and negative bacteria.Certain antibiotics can treat only gram negative or positive bacteria.When bacteria is unidentified doctors must choose an antibiotic that work for all types of bacteria.
Why do some antibiotics work better against gram positive then gram negative bacteria?
Part of describing the function of an antibiotic is stating whether it is effective against Gram-positive bacteria, Gram-negative bacteria or both. (There are other aspects such as whether there is effect on aerobic versus anaerobic bacteria (those that can versus cannot survive in the presence of oxygen), but I'll address that some other time).Some antibiotics have broad spectrum activity, being able to kill Gram-positive and Gram-negative bacteria. At first that might seem like a good thing, and indeed it is when you are treating an infection with an unknown bacterium. However, broad spectrum activity is not desirable when you know exactly what bacterium you are trying to eliminate. If possible, it's much better to target treatment more specifically against the offending bacterium for various reasons, such as to reduce the risk of resistance emerging in other bacterial groups.Some antibiotics are narrow spectrum. Some are most effective against Gram-positive or Gram-negative bacteria, with little activity against the other. In general, we want to use an antibiotic of the most narrow spectrum possible.
Do Antibiotics only work on bacteria or virus?
Antibiotics only work on bacteria.
Why do antibiotics work against bacteria and not viruses?
Antibiotics disrupt bacterial cell processes that result in either killing the bacteria, preventing it from reproducing, or preventing it from causing symptoms in humans. For example: penicillin disrupts the synthesis of the bacterial cell wall in mostly gram positive bacteria. This prevents the growth of the target bacteria. Any gram negative bacteria will be unaffected by penicillin because they have a different process of synthesizing cell walls that is not disrupted by penicillin. Viruses don't even have a cell wall, they have a protein coat and sometimes an envelope. Neither of these are affected by penicillin. So antibiotics target specific processes that only occur in specific types of bacteria, so each antibiotic will only work on some bacteria and never on viruses. The virus version of antibiotics are called interferon, they disrupt processes that are specific to viruses.
What is the purpose of control test in gram stain?
Gram staining is a simple staining test that simply identifies the two main groups of bacteria. Gram positive, and gram negative. Down a microscope, gram pos look like a dark blue/purple colour, and gram neg look red. It is to do with what the wall of the bacteria comprises of, and without going into too much detail, certain drugs work on gram pos bacteria, and others wont. Likewise for gram neg.
Why is gram staining important?
It tells the microbiologist/clinician facts about the cell wall construction of the bacterium. This then indicates which antibiotics to prescribe if you are trying to get rid of a bacterial infection.
Why does penicillin not work on all bacteria?
Penicillin comes from an antibiotic made by one microbe that acts only against certain others. Some microbes are just resistant toward the antibiotic and another will have to be used. At times not enough or a dose that is too weak will prevent the antibiotic from working. Some antibiotics will work only on Gram negative or Gram positive bacteria. Some are broad spectrum and will work on both.It just is that penicillin resistant bacteria are not affected by penicillin. These have mutated and evolved to resist penicillin. These are often called "super bugs".
Does the gram stain procedure work for all bacteria?
Yes. The gram stain procedure separates all bacteria into one of two groups - into gram-negative bacteria which do not stain purple and into gram-positive cells which do stain purple. In structural terms, the ability of a cell to become stained during the gram stain procedure is due to the chemical makeup of the cell wall.
