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Unformatted text preview: cs has dramatically increased the frequency of antibiotic resistance in bacterial populations. Chicken feed suppliers and chicken growers add antibiotics to chicken feed in order to produce healthier chickens and prevent harmful bacteria from getting into meat and eggs. This use of antibiotics results in populations of bacteria resistant to whichever antibiotic is being used. A commonly used antibiotic is kanamycin. Kanamycin interferes with bacterial growth by interacting with a subunit of bacterial ribosomes, inhibiting protein synthesis because it interferes with the translation stage of protein synthesis. Reports of severe gastroenteritis linked to eating raw or undercooked eggs have led the FDA to investigate possible sources of the contamination. Scientists have isolated Salmonella enteriditis bacteria from batches of eggs known to have caused food poisoning and found that they carry plasmids containing kanamycin resistant genes. They have also found that these contaminated eggs came from three different chicken farms. These three farms are geographically separate from each other, located in three different states. An important question to address is whether there is a shared source for the bacterial contamination among the three farms (e.g., shared feed producer, shared source of laying hens), or whether each occurrence of kanamycin‐resistant bacteria is unique to each farm (that is, they do not share a source). Scientists know that there are three different genes commonly responsible for kanamycin resistance. Each different gene codes for a different enzyme that chemically alters the kanamycin molecule in different ways. These enzymes occur in the area between the inner and outer bacterial membranes (periplasmic space), and disable the kanamycin after it passes through the outer membrane. The modification in the kanamycin molecule prevents it from being taken up by the inner membrane and thus prevents it from reaching the ribosomes and inhibiting protein synthesis. Bacteria that contain a...
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This note was uploaded on 02/06/2014 for the course BIO 110 taught by Professor Hass during the Fall '11 term at Pennsylvania State University, University Park.
- Fall '11