Question

1. To determine the likelihood that a patient with a bacterial infection who is in the intensive care unit (ICU) of a hospital could be successfully treated with antibiotic therapies, researchers investigated the frequency of antibiotic resistance in bacteria isolated from patients in ICUs in the United States from 1994 to 2000. The data from the study are shown in the table, along with the overall change in the frequency of bacterial resistance in patient samples from 1994 to 2000. INCIDENCE OF ANTIBIOTIC RESISTANCE IN PATIENTS ADMITTED TO ICUS FROM 1994 TO 2000 Percent of All Samples Demonstrating Overall Change in Percent Resistance to Antibiotic Antibiotic Resistance in 2000 Antibiotics from 1994 to 2000 Ciprofloxacin 19 +10 Gentamicin 22 Ampicillin 65 +3 Imipenem 11 Tazobactam 22 +6 (a) A patient was admitted to the ICU in December 2000 with an uncharacterized bacterial infection. Based on the data from the study, identify the following. • The antibiotic that was most likely to be effective for treating the infection • The antibiotic that was least likely to be effective for treating the infection (b) Using the data, provide justification for the claim that antibiotic resistance may arise in bacterial species. (c) Describe THREE different processes by which antibiotic resistance develops in individual bacterial cells. (d) Describe TWO features of natural selection that lead to the spread of antibiotic resistance in a population over many generations. Give ONE reason that the development of antibiotic resistance is an example of evolution. (e) Giving low doses of antibiotics to beef cattle to control the population sizes of intestinal bacteria can result in more efficient uptake of food materials by the cattle. Pose an ethical question that the Food and Drug Administration (FDA) should consider when deciding whether to approve this type of antibiotic use in beef cattle.

Answer 1

A) 1. According to the data provided , the antibiotic that was most likely to be effective for treating the infection is Imipenam because of its least resistance .

2. According to the data provided , the antibiotic that was least likely to be effective for treating the infection is Ampicillin because of its highest resistance

(b) Antibiotic resistance occurs when bacteria develop the ability to defeat the drugs designed to kill them. This adaptation is the case due to the principle that natural seleciton.

c) Three different process by which antibiotic resistance develops in individual bacterial cells are :-

1. The enzymatic inactivation method of resistance.

The bacteria spontaneously produces an enzyme that can degrade the antibiotic, e.g. The beta-lactamases.

Can be passed between different species.

2. The enzymatic addition method of resistance.

Bacteria may express enzymes that add a chemical group to the antibiotic, inhibiting its activity. For example, some bacteria can express enzymes that add an amino, acetyl or adenosine group to aminoglycosides, making them inactive.

3. The efflux method of antibiotic resistance.

Bacteria may acquire an inner membrane protein that actively pumps the antibiotic (commonly tetracycline) out of the cell. This is how streptococci become resistant to macrolides. May also have an important role in organisms gaining higher levels of resistance because the bacterium is under attack from the antibiotic for longer (I.e. has more time to develop other forms of resistance).