Hepatitis with cholestatic jaundice occurs most frequently as an adverse reaction to the following preparation of erythromycin

Correct Answer: C

Rationale: The correct answer is C) Erythromycin estolate. Erythromycin estolate is known to be associated with an increased risk of cholestatic jaundice compared to other erythromycin preparations. This adverse reaction occurs due to the estolate salt form of erythromycin causing a higher incidence of hepatotoxicity, leading to cholestatic jaundice. Option A) Erythromycin base, B) Erythromycin stearate, and D) Erythromycin ethylsuccinate are less likely to cause cholestatic jaundice compared to erythromycin estolate. Erythromycin base is the basic form of the drug, stearate is a salt form with lower risk of liver toxicity, and ethylsuccinate is another salt form that is less likely to cause cholestatic jaundice. Educationally, understanding the differences in erythromycin preparations and their associated adverse effects is crucial for healthcare professionals to make informed decisions when prescribing medications. This knowledge helps in preventing potential harm to patients and in providing safer and more effective healthcare.

Correct Answer: B

Rationale: In the context of this question on the addition of clavulanic acid to amoxicillin, the correct answer is B) Enhance the anti-bacterial activity of amoxicillin. Clavulanic acid is a beta-lactamase inhibitor that is often combined with amoxicillin to protect amoxicillin from being degraded by beta-lactamase enzymes produced by certain bacteria. By inhibiting beta-lactamase, clavulanic acid allows amoxicillin to exert its antibacterial effects effectively, hence enhancing its antibacterial activity. Option A) Decrease the renal excretion of amoxicillin is incorrect because clavulanic acid does not affect the renal excretion of amoxicillin. Option C) Decrease the biotransformation of amoxicillin is incorrect as clavulanic acid's main role is to protect amoxicillin from enzymatic degradation rather than affecting its biotransformation. Option D) To increase oral absorption of amoxicillin is also incorrect because clavulanic acid does not directly impact the oral absorption of amoxicillin. In an educational context, understanding the rationale behind combining clavulanic acid with amoxicillin is crucial for healthcare professionals, particularly in the field of pharmacology and infectious diseases. This knowledge helps in choosing the appropriate antibiotic therapy, especially in cases where beta-lactamase-producing bacteria are involved. It also underscores the importance of combination therapy in combating antibiotic resistance, as these combinations can enhance the effectiveness of antibiotics against resistant strains.

Correct Answer: A

Rationale: In the context of this question, the correct answer is A) Pertussis. Erythromycin is the drug of choice for treating pertussis, also known as whooping cough, due to its effectiveness against the causative bacterium, Bordetella pertussis. Erythromycin works by inhibiting bacterial protein synthesis, thus helping to eradicate the infection. Option B) Gonococcal urethritis is typically treated with antibiotics such as ceftriaxone or azithromycin, as gonorrhea is caused by Neisseria gonorrhoeae which has developed resistance to erythromycin. Option C) Prophylaxis of bacterial endocarditis usually involves antibiotics like amoxicillin or clindamycin, not erythromycin. Option D) Chlamydial infections are commonly treated with antibiotics such as azithromycin or doxycycline, as Chlamydia trachomatis is not effectively treated by erythromycin. Educationally, understanding the appropriate use of antibiotics in specific infections is crucial for healthcare providers to effectively treat patients and prevent the development of antibiotic resistance. It is important for students to grasp the rationale behind drug choices to provide safe and evidence-based care to patients.

Correct Answer: C

Rationale: In this question, the correct answer is C) Tetracyclines and chloramphenicol. These antibiotics inhibit protein synthesis in cells by targeting the bacterial ribosomes, thereby preventing the translation of mRNA into proteins. Tetracyclines bind to the 30S ribosomal subunit, while chloramphenicol inhibits the peptidyl transferase activity of the 50S ribosomal subunit. Option A) Sulphonamides and PAS are not antibiotics that inhibit protein synthesis. Sulphonamides work by inhibiting folic acid synthesis, while PAS is used in the treatment of tuberculosis. Option B) Isoniazid and PAS are also not antibiotics that inhibit protein synthesis. Isoniazid is used in the treatment of tuberculosis by inhibiting mycolic acid synthesis in the bacterial cell wall. Option D) Penicillin and cephalosporins are beta-lactam antibiotics that inhibit cell wall synthesis by targeting penicillin-binding proteins, not protein synthesis. Understanding the mechanisms of action of different antibiotics is crucial for healthcare professionals to make informed decisions regarding the selection of appropriate antibiotics for treating bacterial infections. Knowing which antibiotics target protein synthesis, cell wall synthesis, or other bacterial processes helps in effectively combating bacterial infections and preventing antibiotic resistance.

Correct Answer: B

Rationale: In the context of drugs for the immune system, understanding the activity of antibiotics like Streptomycin at different pH levels is crucial for their effectiveness. The correct answer, B) pH 8.5 than pH 5.5 of urine, is based on the pharmacokinetics of Streptomycin. Streptomycin is more active at alkaline pH levels like 8.5 because it is a weak base and its solubility and activity increase in alkaline environments. This is important to know for dosing and treatment efficacy. Option A) pH 5.5 than pH 8.5 of urine is incorrect because acidic pH levels would actually decrease the activity of Streptomycin. In acidic conditions, Streptomycin may become less soluble and therefore less effective. Option C) Equally active at all pH of urine is incorrect because, as mentioned earlier, Streptomycin's activity is pH-dependent due to its chemical properties as a weak base. It is not equally active across all pH levels. Option D) All of the above is incorrect because Streptomycin does not exhibit consistent activity across different pH levels. Understanding this concept is important in clinical practice when prescribing antibiotics and ensuring their optimal effectiveness in treating infections.