Instructions: The assignment consists of 3 case studies involving the use of ant

Instructions:
The assignment consists of 3 case studies involving the use of antibiotics.
Questions are to be answered in detail and presented as a typed document.
The questions should be answered using lecture material as well as additional sources such as recommended texts and other supplementary material. All referenced material should be cited in the text and included in a bibliography.
Case study 1
Barry presents with constant pain in the upper right quadrant, fever, and nausea. Upon further investigation, Barry is diagnosed with acute cholecystitis. Blood culture reports indicate evidence of sepsis, which is likely due to the enteric bacteria Escherichia coli. Barry is prescribed intravenous amoxicillin, 1 g every 6 hours.
Explain the mode of action of this class of antibiotics, regarding their specific molecular targets, and how they result in the death of the bacterium. (2 marks) Initially, the treatment appears to be effective. However, after several days, the symptoms return. The prescribed antibiotic now appears to be less effective.
How can bacteria produce resistance to this class of antibiotics? Why does cross- resistance occur? It is suggested that additional treatments be used to improve the effectiveness of amoxicillin.
What can be used to enhance the effectiveness of this class of antibiotics in resistant bacteria?
Why is it generally considered more difficult to treat infections caused by gram-negative bacteria?
Case study 2
Larry has been experiencing fever, pleuritic chest pain, and a new-onset cough. Chest X- ray indicates community-acquired pneumonia (CAP). Patient mortality and hospital length of stay are significantly reduced if treatment is commenced within 8 hours, and so Larry is immediately administered intravenous penicillin, 1 g every 8 hours for 7 days.
However, within 1 hour of initial administration, Larry develops urticaria and bronchospasm, and finally anaphylaxis.
How is anaphylaxis normally treated to restore airway function in this patient?
What are the allergenic determinants behind this hypersensitivity reaction?
Will the patient likely experience a similar reaction to carbenicillin and cefuroxime?
Due to the immediate hypersensitivity reaction, Larry’s penicillin treatment has been replaced with oral moxifloxacin, 400 mg daily for 7 days.
What is the mechanism of action for this class of antibiotics?
Microbiological investigation of Larry’s sputum reveals that the infection is due to Mycoplasma pneumoniae. As such another antibiotic, oral doxycycline (200 mg then 100 mg daily for 5 days), has been added to the treatment.
What is the mechanism of action for this class of antibiotics?
What adverse effects may be seen with the use of tetracyclines, and when should they not be used? What is the mechanism behind these effects?
Case study 3
Sally complains of frequent urination accompanied by a burning sensation. Upon examination, Sally’s urine sample appears cloudy. Urinalysis confirms the diagnosis of a urinary tract infection (UTI) caused by Staphylococcus saprophyticus. Sally is subsequently administered intramuscular gentamicin, 3 mg/kg/day for 7 days, with blood concentrations of the antibiotic being monitored regularly. High fluid intake and complete bladder emptying have been recommended to Sally to assist with antimicrobial therapy for UTIs. The overall treatment has appeared effective in treating the infection.
1. Describe the mechanism of action for the antibiotic gentamicin. Why must the blood concentrations of gentamicin be monitored regarding potential toxicities?
This was the third UTI that Sally contracted within the last 12 months. As such, it is suggested that Sally begin antimicrobial prophylaxis to prevent future infection. Sally has been prescribed oral trimethoprim and sulfamethoxazole (cotrimoxazole, 160 mg, and 800 mg respectively), to be taken at night for the next 6 months.
Describe the mechanism of action for the two antibiotics, trimethoprim, and sulfamethoxazole.
Why are these two drugs more effective when used in combination?
Describe how bacterial resistance can develop to these two drugs.