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Question 1
Correct
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A 6-year-old child with a few itchy honey crusted sores on her left cheek is brought in by her mother. Following a thorough examination of the child, you diagnose impetigo and recommend a course of topical fusidic acid.Fusidic acid's mode of action is which of the following?
Your Answer: Inhibition of protein synthesis
Explanation:By binding EF-G-GDP, fusidic acid prevents both peptide translocation and ribosome disassembly, which slows protein synthesis. Because it has a novel structure and mechanism of action, it is unlikely to cause cross-resistance with existing antibiotics.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 2
Incorrect
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Regarding gentamicin, which of the following statements is INCORRECT:
Your Answer: Gentamicin is indicated for treatment of infective endocarditis.
Correct Answer: Gentamicin typically causes acute glomerulonephritis in toxicity.
Explanation:Gentamicin is the aminoglycoside of choice in the UK and is used widely for the treatment of serious infections. It has a broad spectrum but is inactive against anaerobes and has poor activity against haemolytic streptococci and pneumococci. When used for the blind therapy of undiagnosed serious infections it is usually given in conjunction with a penicillin or metronidazole (or both). The main toxic effects are nephrotoxicity and ototoxicity due to damage to the vestibulocochlear nerve (CN VIII).Gentamicin is contraindicated in myasthenia gravis and should be used with caution in renal disease which may result in accumulation and a greater risk of toxic side effects.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 3
Correct
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A patient who shows symptoms of infection and is admitted under supervision of the medical team. The organism which caused this, is a Gram-negative bacterium, according to the culture. A penicillin therapy is suggested by the microbiologist.Which of the penicillins listed below is the most effective against Gram-negative bacteria?
Your Answer: Amoxicillin
Explanation:Amoxicillin and Ampicillin are more hydrophilic (broad-spectrum) penicillins than benzylpenicillin and phenoxymethylpenicillin. Because they may penetrate through gaps in the outer phospholipid membrane, they are effective against Gram-negative bacteria. Amoxicillin and Ampicillin are resistant to penicillinase-producing microbes.Community-acquired pneumonia, otitis media, sinusitis, oral infections, and urinary tract infections are among the most prevalent conditions for which they are prescribed. The normal adult oral dose of Amoxicillin is 500 mg three times/day, which can be increased to 1 g three times/day if necessary. Ampicillin is given to adults in doses of 0.5-1 g every 6 hours.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 4
Correct
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You're examining a 58-year-old male who has cellulitis in his left leg. Because he is allergic to penicillin, you start him on erythromycin.Which of the following statements about erythromycin is correct?
Your Answer: It can be used to treat Legionnaire’s disease
Explanation:Bacteriostatic antibiotics include erythromycin and other macrolide antibiotics. They work by attaching to the bacterial ribosome’s 50S subunit, preventing translocation and thereby protein synthesis. Macrolide antibiotics are actively concentrated inside leukocytes and delivered to the infection site as a result.Erythromycin is an orally active antibiotic that can also be given intravenously. It is metabolized in the liver and eliminated in the bile and has a biological half-life of 1.5 hours.It has a similar antibacterial spectrum to benzylpenicillin (i.e., a narrow spectrum, primarily against Gram-positive pathogens) and can be used as a penicillin substitute in people who are allergic to penicillin.Erythromycin is unsuccessful in the treatment of meningitis because it does not penetrate the central nervous system well enough. It is efficient against a variety of unusual pathogens, unlike penicillin.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 5
Correct
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A 23 year old student presents to ED with a widespread maculopapular rash. She recently had a sore throat and was started on a course of antibiotics. The most likely antibiotic that she was prescribed is:
Your Answer: Amoxicillin
Explanation:Maculopapular rashes are commonly seen with ampicillin and amoxicillin. However they are not usually related to true penicillin allergy. Very often, they occur in patients with glandular fever and so, broad-spectrum penicillins should not be used blindly, for management and treatment of a sore throat. There is also an increased risk of rash in patients with acute or chronic lymphocytic leukaemia or in cytomegalovirus infection.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 6
Correct
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You examine a 34-year-old lady with symptoms that are consistent with acute sinusitis. You're thinking about giving her doxycycline for treatment.What is doxycycline's mechanism of action?
Your Answer: Inhibition of protein synthesis
Explanation:Doxycycline and other tetracycline antibiotics attach to the 30S subunit of the bacterial ribosome, preventing aminoacyl-tRNA binding and so protein synthesis beginning.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 7
Correct
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What is the mechanism of action of penicillin antibiotics:
Your Answer: Inhibition of bacterial cell wall synthesis
Explanation:Penicillins and the other ß-lactam antibiotics are bactericidal. They produce their antimicrobial action by preventing cross-linkage between the linear peptidoglycan polymer chains that make up the bacterial cell wall. They, therefore, inhibit cell wall synthesis.The integrity of the ß-lactam ring is essential for antimicrobial activity. Many bacteria (including most Staphylococci) are resistant to benzylpenicillin and phenoxymethylpenicillin because they produce enzymes (penicillinases, ß-lactamases) that open the ß-lactam ring.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 8
Correct
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A 78-year-old man develops renal impairment and hearing loss after inpatient management for sepsis.Which of these antibiotics is most likely to have been used?
Your Answer: Gentamicin
Explanation:Gentamicin, an aminoglycoside antibiotic, acts by binding to the 30S subunit of the bacterial ribosome inhibiting the binding of aminoacyl-tRNA, and thus prevents initiation of protein synthesis.Two of its most notable side effects are reversible nephrotoxicity(caused by the inhibition of protein synthesis in renal cells, which causes acute tubular necrosis) and hearing loss (caused by damage to the vestibular apparatus of the inner ear). Both side effects are dose-related and occur commonly in the elderly.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 9
Incorrect
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Regarding amoxicillin, which of the following statements is INCORRECT:
Your Answer: It is used first line for acute otitis media.
Correct Answer: It is used first line for bacterial tonsillitis.
Explanation:Amoxicillin is a derivative of ampicillin and has a similar antibacterial spectrum. It is better absorbed than ampicillin when given orally, producing higher plasma and tissue concentrations; unlike ampicillin, absorption is not affected by the presence of food in the stomach. The adverse effects of amoxicillin are mainly gastrointestinal and mild and include nausea, vomiting and diarrhoea. Amoxicillin is used first line for low to moderate severity community acquired pneumonia, exacerbations of chronic bronchitis, for acute otitis media, for acute sinusitis, for oral infections/dental abscess, for Listeria meningitis (in combination with another antibiotic), for infective endocarditis (in combination with another antibiotic) and for H. Pylori eradication (in combination with metronidazole/clarithromycin and a PPI). Penicillin V is used first line for bacterial tonsillitis; amoxicillin should be avoided in blind treatment of a sore throat as there is a high risk of a rash if glandular fever is present.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 10
Correct
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A 23-year-old student presents to the emergency department with a terrible headache, photophobia, and a fever. On her lower limbs, you see a non-blanching purpuric rash. In the department, a lumbar puncture is conducted. What do you think you'll notice on Gram stain:
Your Answer: Gram negative diplococci
Explanation:Bacterial meningitis and septicaemia are most commonly caused by meningococcal bacteria. The Gram-negative diplococci Neisseria Meningitidis causes meningitis. Gram stain and culture of CSF identify the etiologic organism, N meningitidis. In bacterial meningitis, Gram stain is positive in 70-90% of untreated cases, and culture results are positive in as many as 80% of cases.
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This question is part of the following fields:
- Infections
- Microbiology
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Question 11
Incorrect
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A young female was diagnosed with a urinary tract infection and was sent home with medications. However, after 48 hours of discharge, she returned to the hospital because there had been no relief from her symptoms. She is pregnant in her second trimester. The urine sensitivity test report is still unavailable. Fresh blood tests were sent, and her estimated GFR is calculated to be >60 ml/minute. She was prescribed nitrofurantoin 100 mg modified-release orally twice a day for two days.Out of the following, which antibiotic is most appropriate to be prescribed to this patient?
Your Answer: Amoxicillin
Correct Answer: Cefalexin
Explanation:The NICE guidelines for pregnant women with lower UTIs are:1. Prescribe an antibiotic immediately, taking into account the previous urine culture and susceptibility results or avoiding past antibiotics that may have caused resistance2. Obtain a midstream urine sample before starting antibiotics and send for urine culture and susceptibility – Review the choice of antibiotic when the results are available – change the antibiotic according to susceptibility results if the bacteria are resistant, using a narrow-spectrum antibiotic wherever possibleThe first choice of antibiotics for pregnant women aged 12 years and over is:1. Nitrofurantoin100 mg modified-release PO BD for 3 days – if eGFR >45 ml/minuteThe second-choice (no improvement in lower UTI symptoms on first-choice for at least 48 hours, or when first-choice is not suitable) are:1. Amoxicillin 500 mg PO TDS for seven days (ONLY if culture results available and susceptible)2. Cefalexin500 mg BD for seven daysAlternative second-choices – consult local microbiologist, choose antibiotics based on culture and sensitivity results
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 12
Correct
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A 30-year-old woman presents with a history of fever and sore throat. On examination, there is tonsillar exudate and cervical lymphadenopathy and a diagnosis of tonsillitis is made. A course of penicillin is prescribed.What is the mechanism of action of penicillin?
Your Answer: Inhibition of cell wall synthesis
Explanation:Penicillin is bactericidal and produces its antimicrobial action by preventing cross-linkage between the linear peptidoglycan polymer chains that make up the bacterial cell wall. This action inhibits cell wall synthesis.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 13
Incorrect
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A 22-year-old man comes to the emergency department with a human bite injury to his hand received from a punch during a fight 3 hours earlier outside a bar. On closer inspection, you discover bite marks on his first and second knuckles. Which of the following is the best treatment option for this patient:
Your Answer: IM ceftriaxone
Correct Answer: Oral co-amoxiclav for 7 days
Explanation:Even if there is no evidence of infection, prophylactic antibiotics should be administered for all human bite wounds that are less than 72 hours old. The first-line therapy is 7 days of co-amoxiclav. In penicillin-allergic people, metronidazole + doxycycline is an option. Streptococcus spp., Staphylococcus aureus, Haemophilus spp., Eikenella corrodens, Bacteroides spp., and other anaerobes are the most prevalent organisms found in human bites.
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This question is part of the following fields:
- Infections
- Microbiology
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Question 14
Incorrect
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Flucloxacillin is used first line for all of the following infections EXCEPT for:
Your Answer: Osteomyelitis
Correct Answer: Otitis media
Explanation:Flucloxacillin is used first line for treatment of widespread impetigo infection, cellulitis, mastitis, osteomyelitis, septic arthritis, severe erysipelas, severe/spreading otitis externa and infective endocarditis caused by staphylococci. Amoxicillin is first line for acute otitis media.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 15
Correct
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Following a phone call from the microbiology consultant, you evaluate a patient who has been diagnosed with urinary sepsis. Following the results of the blood cultures, he recommends that you add gentamicin to the patient's antibiotic treatment.Gentamicin produces its pharmacological effect by binding to which of the following?
Your Answer: The 30S subunit of the bacterial ribosome
Explanation:Antibiotics with aminoglycosides, such as gentamicin, bind to the 30S subunit of the bacterial ribosome and prevent aminoacyl-tRNA from binding, preventing protein synthesis.They also cause mRNA misreading, resulting in the production of non-functional proteins. This last mechanism is unique to aminoglycosides, and it may explain why they are bactericidal rather than bacteriostatic, as other protein synthesis inhibitors are.Patients with myasthenia gravis should avoid aminoglycosides since they can disrupt neuromuscular transmission. They cross the placenta and are linked to poisoning of the 8th cranial nerve in the foetus, as well as permanent bilateral deafness.It is possible that they will cause deafness, although this is not a contraindication. In individuals with renal impairment, serum aminoglycoside concentrations should be closely monitored, but this is still not considered a contraindication.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 16
Incorrect
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Regarding flucloxacillin, which of the following statements is CORRECT:
Your Answer: It is used first line for empirical treatment of infective endocarditis.
Correct Answer: It is resistant to bacterial beta-lactamases.
Explanation:Flucloxacillin is unique in that it is beta-lactamase stable and it can be used in infections caused by beta-lactamase producing staphylococci e.g. S. aureus. It is acid-stable and can therefore be given by mouth as well as by injection. It is used first line for treatment of widespread impetigo infection, cellulitis, mastitis, osteomyelitis, septic arthritis, severe erysipelas, severe/spreading otitis externa and infective endocarditis caused by staphylococci. The most common adverse effects of flucloxacillin include nausea, vomiting, skin rash, and diarrhoea. Cholestatic jaundice and hepatitis may occur very rarely, up to two months after treatment with flucloxacillin has been stopped. Administration for more than 2 weeks and increasing age are risk factors. First line treatment of animal and human bites is co-amoxiclav.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 17
Incorrect
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Dysuria and urinary frequency are symptoms of a 29-year-old woman. A urine dipstick is used to detect the presence of blood, protein, leucocytes, and nitrites in the urine. You diagnose a urinary tract infection and give antibiotics to the patient.In the United Kingdom, which of the following antibiotics has the highest percentage of E.coli resistance?
Your Answer: Cefalexin
Correct Answer: Trimethoprim
Explanation:In the United Kingdom, antibiotic resistance is becoming a significant factor in the treatment of urinary tract infections and pyelonephritis. E. coli (the main causative organism of both urinary tract infections and acute pyelonephritis) resistance to the following antibiotics in laboratory-processed urine specimens is:30.3 percent trimethoprim (varies by area from 27.1 to 33.4 percent )19.8 percent co-amoxiclav (varies by area from 10.8 to 30.7 percent )Ciprofloxacin (Cipro): 10.6% (varies by area from 7.8 to 13.7 percent )Cefalexin has a concentration of 9.9%. (varies by area from 8.1 to 11.4 percent )
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 18
Incorrect
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Which of the following is NOT a notifiable disease:
Your Answer: Legionnaires' disease
Correct Answer: HIV
Explanation:HIV mainly infects CD4+ T helper cells. Viral replication results in progressive T-cell depletion and impaired cell-mediated immunity with subsequent secondary opportunistic infections and increased risk of malignancy. B-cell function is also reduced as a result of lack of T-cell stimulation.HIV is not a notifiable disease.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 19
Correct
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A patient allergic to penicillin and with marked cellulitis presents and you decide to start him on erythromycin.Which statement about macrolide antibiotics is true?
Your Answer: They are actively concentrated within leukocytes
Explanation:Macrolide antibiotics are bacteriostatic. They act by binding to the 50S subunit of the bacterial ribosome inhibit protein synthesis. Macrolide antibiotics are actively concentrated within leukocytes, because of this, they are transported into the site of infection.Macrolide antibiotics are not effective in meningitis as they do not penetrate the central nervous system well. They are mainly against Gram-positive organisms and can be used as an alternative in patients with penicillin allergy.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 20
Correct
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You investigated a patient with a chest infection and want to start antibiotics right away. The patient says they she can't take cephalosporins when you ask about allergies.Choose the 'second-generation' cephalosporin from the following choices?
Your Answer: Cefuroxime
Explanation:Cephalosporins of the first generation include cephalexin, cefradine, and cefadroxil. Urinary tract infections, respiratory tract infections, otitis media, and skin and soft-tissue infections are all treated with them.Second-generation cephalosporins include cefuroxime, cefaclor, and cefoxitin. These cephalosporins are less vulnerable to beta-lactamase inactivation than the ‘first-generation’ cephalosporins. As a result, they’re effective against germs that are resistant to other antibiotics, and they’re especially effective against Haemophilus influenzae.Cephalosporins of the third generation include cefotaxime, ceftazidime, and ceftriaxone. They are more effective against Gram-negative bacteria than second generation’ cephalosporins. They are, however, less effective against Gram-positive bacteria such Staphylococcus aureus than second-generation cephalosporins.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 21
Incorrect
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A young female was diagnosed with a urinary tract infection and was sent home with medications. However, after 48 hours of discharge, she returned to the hospital because there had been no relief from her symptoms. The urine sensitivity test report is still unavailable. Fresh blood tests were sent, and her estimated GFR is calculated to be >60 ml/minute. She was prescribed nitrofurantoin 100 mg modified-release orally twice a day for two days.Out of the following, which antibiotic is most appropriate to be prescribed to this patient?
Your Answer: Amoxicillin
Correct Answer: Fosfomycin
Explanation:The NICE guidelines for women with lower UTIs who are not pregnant are:1. Consider prescribing a different antibiotic if symptoms do not improve within 48 hours or worsen at any time 2. If the urine culture and susceptibility test results are available, review the choice of antibiotic according to the results and change the antibiotic accordingly if symptoms are not improving or bacteria is resistant to the prescribed antibioticThe first choice of antibiotics for non-pregnant women aged 16 years and over is:1. Nitrofurantoin100 mg modified-release PO BD for 3 days – if eGFR >45 ml/minute2. Trimethoprim 200 mg PO BD for three daysThe second-choice (no improvement in lower UTI symptoms on first-choice for at least 48 hours, or when first-choice is not suitable) are:1. Nitrofurantoin100 mg modified-release PO BD for three days – if eGFR >45 ml/minute2. Pivmecillinam400 mg PO initial dose, then 200 mg PO TDS for three days3. Fosfomycin 3 g single sachet dose
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 22
Correct
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Regarding drug interactions with erythromycin, which of the following statements is INCORRECT:
Your Answer: Erythromycin decreases plasma levels of warfarin.
Explanation:Erythromycin and clarithromycin inhibit cytochrome P450-mediated metabolism of warfarin, phenytoin and carbamazepine and may lead to accumulation of these drugs. There is an increased risk of myopathy (due to cytochrome P450 enzyme CYP3A4 inhibition) if erythromycin or clarithromycin is taken with atorvastatin or simvastatin. Erythromycin increases plasma concentrations of theophylline, and theophylline may also reduce absorption of oral erythromycin. All macrolides can prolong the QT-interval and concomitant use of drugs that prolong the QT interval is not recommended.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 23
Correct
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All of the following statements regarding metronidazole are correct except:
Your Answer: Metronidazole reduces the anticoagulant effect of warfarin.
Explanation:The anticoagulant effect of warfarin is enhanced by metronidazole. If use of both cannot be avoided, one must consider appropriately reducing the warfarin dosage. With alcohol, metronidazole can cause a disulfiram-like reaction, with symptoms like flushing, headaches, dizziness, tachypnoea and tachycardia, nausea and vomiting. The common side effects of metronidazole include a metallic taste and gastrointestinal irritation, in particular nausea and vomiting. These side effects are more common at higher doses. This drug has high activity against anaerobic bacteria and protozoa, and is well absorbed orally. For severe infections, the intravenous route is normally reserved.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 24
Correct
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All of the following statements are correct regarding penicillin antibiotics except:
Your Answer: Penicillins are of no use in meningitis as they are unable to penetrate into the cerebrospinal fluid.
Explanation:Penicillin penetration into the cerebrospinal fluid is generally poor. However, when the meninges are inflamed, as in meningitis, penetration of penicillin is increased. Benzylpenicillin should be given before transfer to hospital if meningococcal disease (meningitis with non-blanching rash or meningococcal septicaemia) is suspected, once this does not delay transfer. Benzylpenicillin is no longer the drug of first choice for pneumococcal meningitis.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 25
Incorrect
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In a ward round, you come across a patient's treatment chart prescribed an antibiotic to fight his infection. This antibiotic disrupts cell membrane function.Which of the following antimicrobial drugs is prescribed to this patient?
Your Answer: Vancomycin
Correct Answer: Nystatin
Explanation:Nystatin binds ergosterol (unique to the fungi cell membrane) and forms membrane pores that allow K+ leakage, acidification, and subsequent death of the fungus.Vancomycin inhibits cell wall peptidoglycan formation by binding the D-Ala-D-Ala portion of cell wall precursors. Flucloxacillin inhibits the synthesis of bacterial cell walls. It inhibits cross-linkage between the linear peptidoglycan polymer chains that make up a major component of the cell wall of Gram-positive bacteria. Trimethoprim inhibits bacterial dihydrofolate reductase.Isoniazid decreases the synthesis of mycolic acids in mycobacteria.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 26
Correct
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Which of the following side effects is most likely caused by erythromycin:
Your Answer: QT - prolongation
Explanation:The side effects of erythromycin include abdominal pain, anaphylaxis, cholestatic hepatitis, confusion, diarrhoea, dyspepsia, fever, flatulence, hallucinations, hearing loss, headache, hypertrophic pyloric stenosis, hypotension, Interstitialnephritis, mild allergic reactions, nausea, nervous system effects,including seizures, pain, pruritus, pseudomembranous colitis, QT prolongation, rash, skin eruptions, tinnitus, urticaria, ventricular arrhythmias, ventricular tachycardia, vertigo, vomiting
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 27
Correct
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Following the administration of a drug that was started a few months earlier, a patient presents with features of peripheral neuropathy.Which of the following drugs is most likely to cause peripheral neuropathy?
Your Answer: Isoniazid
Explanation:Isoniazid, a first-line agent for the treatment of tuberculosis, has the commonest side effect of peripheral neuropathy. It occurs in up to 20% of patients taking the drug at a dose > 6 mg/kg daily. Isoniazid combines with pyridoxine (vitamin B6) to form hydrazone, which is excreted in the urine. This causes a deficiency of biologically active pyridoxine leading to peripheral neuropathy.Peripheral neuropathy of isoniazid is prevented by the co-administration of pyridoxine at a dose of 10 mg for each 100 mg of isoniazid given.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 28
Correct
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Regarding ampicillin, which of the following statements is CORRECT:
Your Answer: Ampicillin may cause a widespread maculopapular rash in a patient with glandular fever.
Explanation:Ampicillin is a broad-spectrum antibiotic, active against certain Gram-positive and Gram-negative organisms but is inactivated by penicillinases (similar to amoxicillin in spectrum). Ampicillin is associated with high levels of resistance, therefore it is often not appropriate for blind treatment of infection. It is principally indicated for the treatment of exacerbations of chronic bronchitis and middle ear infections, both of which may be due to Streptococcus pneumoniae and H. influenzae, and for urinary tract infections. Maculopapular rashes commonly occur with ampicillin (and amoxicillin) but are not usually related to true penicillin allergy. They almost always occur in patients with glandular fever; thus broad-spectrum penicillins should not be used for blind treatment of a sore throat. The risk of rash is also increased in patients with acute or chronic lymphocytic leukaemia or in cytomegalovirus infection.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 29
Incorrect
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You're currently treating an infection in a patient and trying to figure out which antibiotic would be best.Which of the following antimicrobial drugs inhibits the formation of cell walls?
Your Answer: Doxycycline
Correct Answer: Cefuroxime
Explanation:Cefuroxime and other cephalosporin antibiotics are bactericidal ß-lactam antibiotics. They work similarly to penicillins in that they prevent cross-linking between the linear peptidoglycan polymer chains that make up the bacterial cell wall. As a result, they prevent the formation of cell walls.The following is a summary of the various mechanisms of action of various types of antimicrobial agents:1) Inhibition of cell wall synthesisPenicillinsCephalosporinsVancomycin2) Disruption of cell membrane functionPolymyxinsNystatinAmphotericin B3) Inhibition of protein synthesisMacrolidesAminoglycosidesTetracyclinesChloramphenicol4) Inhibition of nucleic acid synthesisQuinolonesTrimethoprim5-nitroimidazolesRifampicin5) Anti-metabolic activitySulphonamidesIsoniazid
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 30
Incorrect
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A 7-days-old neonate is taken to the emergency department. She's pyretic, lethargic, and unresponsive, and her fontanelle has bulged. Antibiotics are started, and a lumbar puncture reveals Gram-negative rods. Which pathogen is most likely to be the cause:
Your Answer: Neisseria meningitidis
Correct Answer: Escherichia coli
Explanation:Among neonates, group B streptococci (GBS) are the most commonly identified causes of bacterial meningitis, implicated in roughly 50% of all cases. Escherichia coli(Gram-negative rods) accounts for another 20%. Thus, the identification and treatment of maternal genitourinary infections is an important prevention strategy.
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This question is part of the following fields:
- Infections
- Microbiology
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Question 31
Correct
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During her pregnancy, a 28-year-old lady was given an antibiotic. The neonate is born with bilateral deafness as a result of this.From the following antibiotics, which one is most likely to cause this side effect?
Your Answer: Gentamicin
Explanation:Aminoglycosides cross the placenta and are linked to poisoning of the 8th cranial nerve in the foetus, as well as permanent bilateral deafness.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 32
Correct
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You review a patient with urinary sepsis and decide to start her on gentamicin.Which statement about gentamicin is true?
Your Answer: Ototoxicity is a dose-related effect
Explanation:Gentamicin, an aminoglycoside antibiotic, acts by binding to the 30S subunit of the bacterial ribosome inhibiting the binding of aminoacyl-tRNA, and thus prevents initiation of protein synthesis.Gentamicin is given by injection because it is NOT absorbed orally. It is excreted in the kidneys by glomerular filtrationGentamicin is not to be used for the treatment of Neisseria meningitidis, Neisseria gonorrhoea, or Legionella pneumophila.There is a risk of patient going into shock from lipid A endotoxin release.Two of its most notable side effects are hearing loss reversible nephrotoxicity and which are both dose-related and levels should be monitored in patients.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 33
Correct
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You need to give your patient antibiotics, so you call microbiology for some advice.Of the following antibacterial drugs, which of them is a protein synthesis inhibitor?
Your Answer: Erythromycin
Explanation:Bacteriostatic antibiotics include erythromycin and other macrolides. They work by attaching to the bacterial ribosome’s 50S subunit, preventing translocation and, as a result, inhibit protein synthesis. Macrolide antibiotics are actively concentrated inside leukocytes and delivered into the infection site as a result.Action Mechanisms- Examples:Cell wall production is inhibitedVancomycinVancomycinCephalosporinsThe function of the cell membrane is disrupted NystatinPolymyxinsAmphotericin B Inhibition of protein synthesisChloramphenicolMacrolidesAminoglycosidesTetracyclinesNucleic acid synthesis inhibitionQuinolonesTrimethoprimRifampicin5-nitroimidazolesSulphonamidesAnti-metabolic activityIsoniazid
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 34
Correct
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A 40-year-old man complains of pain and redness in his lower thigh due to an insect bite. He was diagnosed with cellulitis. Select the first-line antibiotic for cellulitis.
Your Answer: Flucloxacillin
Explanation:Cellulitis is most commonly caused by bacteria from the group Aß-hemolytic streptococcus. Cellulitis can be caused by animal bites. For uncomplicated cellulitis, flucloxacillin is the first-line antibiotic. Because it is beta-lactamase stable, it is efficient against Staphylococcus aureus.
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This question is part of the following fields:
- Infections
- Microbiology
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Question 35
Correct
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A 58-year-old male has cellulitis of his left leg. Because he is allergic to penicillin, you start him on erythromycin.What is erythromycin's mechanism of action?
Your Answer: Inhibition of protein synthesis
Explanation:Bacteriostatic antibiotics include erythromycin and other macrolide antibiotics. They work by attaching to the bacterial ribosome’s 50S subunit, preventing translocation and thereby protein synthesis. Macrolide antibiotics are actively concentrated inside leukocytes and delivered to the infection site as a result.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 36
Correct
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A patient presents with a cough, productive of green sputum and fever. He was commenced on antibiotics 4 days earlier, but his condition has worsened. There is a documented history of penicillin allergy, and the GP prescribed erythromycin.Erythromycin exert its pharmacological effect by binding to?
Your Answer: The 50S subunit of the bacterial ribosome
Explanation:Macrolides are bacteriostatic antibiotics. They act by binding to the 50S subunit of the bacterial ribosome and inhibit translocation, therefore, inhibiting protein synthesis.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 37
Correct
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Which of the following antibiotics may be used for malaria prophylaxis:
Your Answer: Doxycycline
Explanation:Doxycycline may be used for malaria prophylaxis and as an adjunct to quinine in the treatment of Plasmodium falciparum malaria.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 38
Correct
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A 50-year-old man presents with signs and symptoms of an anaphylactic reaction. His GP had recently given him a new medication.Which one of these is the most likely medication responsible for the drug-induced anaphylactic reaction?
Your Answer: Penicillin
Explanation:The most common cause of drug-induced anaphylaxis is penicillin.The second commonest cause are NSAIDs. Other drugs associated with anaphylaxis are ACE inhibitors and aspirin.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 39
Correct
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Gentamicin is contraindicated in which of the following:
Your Answer: Myasthenia gravis
Explanation:Gentamicin is the aminoglycoside of choice in the UK and is used widely for the treatment of serious infections. It has a broad spectrum but is inactive against anaerobes and has poor activity against haemolytic streptococci and pneumococci. When used for the blind therapy of undiagnosed serious infections it is usually given in conjunction with a penicillin or metronidazole (or both). The main toxic effects are nephrotoxicity and ototoxicity due to damage to the vestibulocochlear nerve (CN VIII).Gentamicin is contraindicated in myasthenia gravis and should be used with caution in renal disease which may result in accumulation and a greater risk of toxic side effects.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 40
Correct
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In a ward round, you come across a patient's treatment chart prescribed an antibiotic to fight his infection. This antibiotic is an inhibitor of cell wall synthesis. Which of the following antimicrobial drugs is prescribed to this patient?
Your Answer: Benzylpenicillin
Explanation:Penicillins and cephalosporins are the major antibiotics that inhibit bacterial cell wall synthesis. They inactivate transpeptidases that help cross-link peptidoglycans in cell walls. Isoniazid decreases the synthesis of mycolic acids in mycobacterium.Clarithromycin binds to the 50S subunit of ribosomes and inhibits protein synthesis. Metronidazole and the other 5-nitroimidazole agents inhibit nucleic acid synthesis by forming toxic free radical metabolites in the bacterial cell that damage DNA. Tetracycline bind to 30S and prevent attachment of aminoacyl-tRNA.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 41
Correct
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Amoxicillin is used first line for all of the following infections EXCEPT for:
Your Answer: Cellulitis
Explanation:Amoxicillin is used first line for low to moderate severity community acquired pneumonia, exacerbations of chronic bronchitis, for acute otitis media, for acute sinusitis, for oral infections/dental abscess, for Listeria meningitis (in combination with another antibiotic), for infective endocarditis (in combination with another antibiotic) and for H. Pylori eradication (in combination with metronidazole/clarithromycin and a PPI). Flucloxacillin is used first line for acute cellulitis.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 42
Incorrect
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Streptococcus viridans has developed subacute bacterial endocarditis in your patient. Which of the following locations is most likely to be the organism's origin?
Your Answer: Colon
Correct Answer: Oral cavity
Explanation:Streptococci that are alpha-haemolytic, such as Streptococcus viridans, are major components of the flora in the oral cavity.
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This question is part of the following fields:
- Infections
- Microbiology
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Question 43
Incorrect
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Herpes simplex encephalitis has a predilection for which of the following sites:
Your Answer: Parietal lobe
Correct Answer: Temporal lobe
Explanation:Herpes simplex virus is the most common cause of infective encephalitis and has a predilection for the temporal lobes. Herpes simplex is transmitted through direct contact. It invades skin locally producing skin vesicles by its cytolytic activity.
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This question is part of the following fields:
- Infections
- Microbiology
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Question 44
Incorrect
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A 60-year-old male presents to the genitourinary clinic with dysuria and urinary frequency complaints. He has a past medical history of benign prostate enlargement, for which he has been taking tamsulosin. There is blood, protein, leucocytes, and nitrites on a urine dipstick. Fresh blood tests were sent, and his estimated GFR is calculated to be >60 ml/minute. A urinary tract infection (UTI) diagnosis is made, and he is prescribed antibiotics. Out of the following, which antibiotic is most appropriate to be prescribed to this patient?
Your Answer: Amoxicillin
Correct Answer: Nitrofurantoin
Explanation:The NICE guidelines for men with lower UTIs are:1. Prescribe an antibiotic immediately, taking into account the previous urine culture and susceptibility results or avoiding antibiotics used previously that may have caused resistance 2. Obtain a midstream urine sample before starting antibiotics and send for urine culture and susceptibility – Review the choice of antibiotic when the results are available AND- change the antibiotic according to susceptibility results if the bacteria are resistant and symptoms are not improving, using a narrow-spectrum antibiotic wherever possibleThe first choice of antibiotics for men with lower UTIs is:1. Trimethoprim200 mg PO BD for seven days2. Nitrofurantoin100 mg modified-release PO BD for 3 days – if eGFR >45 ml/minuteIn men whose symptoms have not responded to a first-choice antibiotic, alternative diagnoses (such as acute pyelonephritis or acute prostatitis) should be considered. Second-choice antibiotics should be based on recent culture and susceptibility results.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 45
Correct
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Regarding macrolide antibiotics, which of the following statements is CORRECT:
Your Answer: Macrolides are first line for treatment of whooping cough.
Explanation:A macrolide antibiotic is recommended first line for whooping cough (if onset of cough is within the previous 21 days)Prescribe clarithromycin for infants less than 1 month of age.Prescribe azithromycin or clarithromycin for children aged 1 month or older, and non-pregnant adults.Prescribe erythromycin for pregnant women.Macrolides interfere with bacterial protein synthesis and are mainly active against Gram-positive organisms. They have a similar antibacterial spectrum to penicillin and are thus a useful alternative in penicillin-allergic patients. Erythromycin is commonly associated with gastrointestinal upset.
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 46
Correct
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A 22-year-old woman is brought in by ambulance from her GP surgery with suspected meningitis. She has been given a dose of benzylpenicillin already.What is the mechanism of action of benzylpenicillin? Select ONE answer only.
Your Answer: Inhibition of cell wall synthesis
Explanation:Penicillins and the other ß-lactam antibiotics are bactericidal. They produce their antimicrobial action by preventing cross-linkage between the linear peptidoglycan polymer chains that make up the bacterial cell wall. They, therefore, inhibit cell wall synthesis.An overview of the different mechanisms of action of the various types of antimicrobial agents is shown below:Mechanism of actionExamplesInhibition of cell wall synthesisPenicillinsCephalosporinsVancomycinDisruption of cell membrane functionPolymyxinsNystatinAmphotericin BInhibition of protein synthesisMacrolidesAminoglycosidesTetracyclinesChloramphenicolInhibition of nucleic acid synthesisQuinolonesTrimethoprim5-nitroimidazolesRifampicinAnti-metabolic activitySulfonamidesIsoniazid
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 47
Correct
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A 61-year-old patient experiences a spontaneous rupture of his Achilles tendon following a course of antibioticsWhich of the antibiotics listed below is MOST likely to be the cause?
Your Answer: Ciprofloxacin
Explanation:Tendinopathy and spontaneous tendon rupture are caused by fluoroquinolones, which are an uncommon but well-known cause. Tendon problems caused by fluoroquinolones are expected to affect 15 to 20 people per 100,000. Patients over the age of 60 are most likely to develop them.It usually affects the Achilles tendon, but it has also been described in cases involving the quadriceps, peroneus brevis, extensor pollicis longus, long head of biceps brachii, and rotator cuff tendons. The exact aetiology is uncertain, although the fluoroquinolone medication is thought to obstruct collagen activity and/or cut off blood supply to the tendon.Other factors linked to tendon rupture spontaneously include:GoutTreatment with corticosteroidsHypercholesterolaemiaLong-term dialysisKidney transplantRheumatoid arthritis
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This question is part of the following fields:
- Infections
- Pharmacology
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Question 48
Correct
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Question 49
Correct
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Question 50
Incorrect
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Regarding ciprofloxacin, which of the following statements is INCORRECT:
Your Answer: Ciprofloxacin is particularly active against Gram-negative bacteria.
Correct Answer: Ciprofloxacin decreases plasma concentrations of theophylline.
Explanation:Ciprofloxacin increases plasma concentrations of theophylline. There is an increased risk of convulsions when quinolones are given with NSAIDs or theophylline. There is an increased risk of tendon damage when quinolones are given with corticosteroids. Quinolones are known to increase the QT-interval and should not be taken with concomitantly with other drugs that are known to cause QT-interval prolongation. There is an increased risk of myopathy when erythromycin or clarithromycin are taken with simvastatin or atorvastatin.
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This question is part of the following fields:
- Infections
- Pharmacology
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SESSION STATS - PERFORMANCE PER SPECIALTY
