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Question 1
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A 30-year-old male presented with a history of bloody and mucoid diarrhoea since that morning. He is also complaining of abdominal spasm and bloating. Which of the following investigations is the most suitable one in this case?
Your Answer: Stool culture and sensitivity
Explanation:In a case of sudden bloody and mucoid diarrhoea, stool culture and sensitivity are required to access which organism is causing the problem and to discuss appropriate antibiotics.
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This question is part of the following fields:
- Infectious Diseases
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Question 2
Incorrect
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A 34-year-old man presents with haemoptysis and weight loss. History reveals he suffers from night sweats and upon auscultation you notice reduced breath sounds over the apex of his right lung and significant nail clubbing. You refer him to a pneumologist who administers the following antibiotics: rifampicin, ethambutol, pyrazinamide and isoniazid. What is the mechanism of action of the first drug?
Your Answer: Inhibit cell wall formation
Correct Answer: Inhibit RNA synthesis
Explanation:Rifampicin specifically inhibits bacterial RNA polymerase, the enzyme responsible for DNA transcription, by forming a stable drug-enzyme complex with a binding constant of 10(-9) M at 37 C.
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This question is part of the following fields:
- Infectious Diseases
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Question 3
Incorrect
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A 45-year-old male patient presents with severe pharyngitis and dysphagia. He's found to be HIV positive and with oesophageal candidiasis. Which of the following regarding HIV virus is correct?
Your Answer: HIV is a DNA virus
Correct Answer: HIV is an RNA virus
Explanation:The human immunodeficiency virus (HIV) is grouped to the genus Lentivirus within the family of Retroviridae, subfamily Orthoretrovirinae. The HIV genome consists of two identical single-stranded RNA molecules that are enclosed within the core of the virus particle. The genome of the HIV provirus, also known as proviral DNA, is generated by the reverse transcription of the viral RNA genome into DNA, degradation of the RNA and integration of the double-stranded HIV DNA into the human genome.
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This question is part of the following fields:
- Infectious Diseases
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Question 4
Correct
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A 20-year-old boy returning from vacation in India presented with a history of fever, myalgia, headache and abdominal pain for 4 days duration. He revealed that he had bathed in a river during his vacation. On examination, he had severe muscle tenderness, hypotension (BP - 80/60 mmHg) and tachycardia (140 bpm). What would be the first step in management?
Your Answer: IV normal saline
Explanation:The history is suggestive of leptospirosis. This is a zoonotic infection caused by a spirochete. As the patient is in shock, resuscitation with IV fluids is the first step in the management. IV antibiotics should be started (Doxycycline or Penicillin) as soon as possible. Other investigations mentioned are important during the management to rule out other possible diagnoses.
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This question is part of the following fields:
- Infectious Diseases
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Question 5
Correct
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A 36-year-old man is scheduled to start on interferon-alpha and ribavirin for the treatment of hepatitis C. His past history includes intravenous drug usage. Which are the most common side effects of interferon-alpha?
Your Answer: Depression and flu-like symptoms
Explanation:Adverse effects due to IFN-alpha have been described in almost every organ system. Many side-effects are clearly dose-dependent. Taken together, occurrence of flu-like symptoms, haematological toxicity, elevated transaminases, nausea, fatigue, and psychiatric sequelae are the most frequently encountered side effects.
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This question is part of the following fields:
- Infectious Diseases
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Question 6
Correct
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A 25-year-old female presented with multiple small genital ulcers, which are painful following a sexual intercourse with an unknown man. Which of the following can be used topically for this presentation?
Your Answer: Acyclovir
Explanation:The most probable diagnosis is Herpes Simplex infection. Topical Acyclovir can be used in early stages.
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This question is part of the following fields:
- Infectious Diseases
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Question 7
Incorrect
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A 19-year-old woman is diagnosed with acute purulent meningitis after returning from a recent holiday abroad. Which of the following investigations is the least relevant?
Your Answer: India ink staining of CSF
Correct Answer: PCR of CSF for Mycobacterium TB
Explanation:Amoebic, bacterial and fungal meningitis may present acutely but this is not common in tuberculous meningitis. Amoebic meningitis is caused by Naegleria fowleri as a result of swimming in infected freshwater. The organism may be found in fresh CSF specimens with phase contrast microscopy.
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This question is part of the following fields:
- Infectious Diseases
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Question 8
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A 28-year-old male complained of an annular rash following an insect bite he received during a hiking trip. Which of the following is the drug of choice?
Your Answer: Doxycycline PO
Explanation:The described rash is the typical rash of erythema migrans of Lyme disease, which is treated by doxycycline PO
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This question is part of the following fields:
- Infectious Diseases
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Question 9
Correct
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A 34-year-old's chest x-ray showed diffuse bilateral alveolar shadows. He also suffers from shortness of breath, weight loss and dry cough due to Kaposi's sarcoma but no fever was noted. Which is the most likely causative organism?
Your Answer: Pneumocystis jiroveci
Explanation:Pneumocystis Jiroveci. This causative organism is responsible for pneumonia in individuals that have a compromised immune system. Symptoms include cyanosis, dry cough and in some cases, diffuse bilateral alveolar shadows on CXR. Co-trimoxazole is normally the treatment for this.
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This question is part of the following fields:
- Infectious Diseases
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Question 10
Correct
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A 40-year-old male returning from an African country, presented with lower abdominal pain and haematuria. Bladder calcifications were detected on abdominal x-ray. Which of the following is the most probable cause?
Your Answer: Schistosoma haematobium
Explanation:Schistosoma haematobium characteristically causes urinary tract disease. S.mansoni, S. mekongi, S. intercalatum, and S. japonicum cause intestinal tract and liver disease.
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This question is part of the following fields:
- Infectious Diseases
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Question 11
Incorrect
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A 20-year-old pregnant female in her first trimester met a child with chickenpox. She was investigated for the varicella antibody, which came back negative. She visited her GP. Which of the following measures is the most appropriate one?
Your Answer: Ig + vaccine
Correct Answer: Ig
Explanation:After the exposure to chickenpox while pregnant, even if the patient is negative for antibodies she requires immunoglobulin to prevent further issues.
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This question is part of the following fields:
- Infectious Diseases
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Question 12
Incorrect
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A baby is born with complications including microcephaly, hepatosplenomegaly and elevated total bilirubin. Which of the following is the most likely diagnosis in this case?
Your Answer: Syphilis
Correct Answer: Cytomegalovirus (CMV)
Explanation:CMV infection is usually asymptomatic in adults. However, if the mother is infected for the first time during pregnancy then there is high chances of this infection passing on to the foetus. CMV infection can cause blindness, deafness, learning difficulties, restricted growth etc. Hepatitis B, herpes simplex, syphilis and HIV do not present with these classical signs of CMV infection in new-borns. It is estimated that 10 stillbirths occur in England and Wales every year due to CMV infection. The foetus is most at risk in early pregnancy. There is no effective prevention.
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This question is part of the following fields:
- Infectious Diseases
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Question 13
Correct
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Sensorineural deafness is strongly associated with which one of the following?
Your Answer: Rubella
Explanation:Primary rubella infection during pregnancy, particularly during the first trimester, can affect several organs and cause birth defects that are responsible for congenital rubella syndrome (CRS). The most common defects of CRS are hearing impairment (unilateral or bilateral sensorineural), eye defects (e.g., cataracts, congenital glaucoma, or pigmentary retinopathy), and cardiac defects (e.g., patent ductus arteriosus or peripheral pulmonic stenosis). Congenital hearing loss is the most common sequela, occurring in approximately 60% of cases, especially when infection occurs in the 4th month of pregnancy.
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This question is part of the following fields:
- Infectious Diseases
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Question 14
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A 22-year-old female presents with a history of a whitish discharge from her vagina. She previously underwent a dental procedure and completed a 7 day antibiotic course prior to it. Which of the following microorganisms has most likely lead to this?
Your Answer: Candida
Explanation:Candida albicans is the most common cause of candidiasis and appears almost universally in low numbers on healthy skin, in the oropharyngeal cavity, and in the gastrointestinal and genitourinary tracts. In immunocompetent individuals, C. albicans usually causes minor localized infections, including thrush (affecting the oral cavity), vaginal yeast infections (if there is an underlying pH imbalance), and infections of the intertriginous areas of skin (e.g., the axillae or gluteal folds). More widespread and systemic infections may occur in immunocompromised individuals (e.g., neonates, diabetics, and HIV patients), with the oesophagus most commonly affected (candida esophagitis). Localized cutaneous candidiasis infections may be treated with topical antifungal agents (e.g., clotrimazole). More widespread and systemic infections require systemic therapy with fluconazole or caspofungin.
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This question is part of the following fields:
- Infectious Diseases
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Question 15
Correct
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An 18-year-old male was diagnosed with meningococcal meningitis, confirmed on lumbar puncture. After 6 months he presents in the infectious clinic with a second episode of meningitis. His past history is clear and he takes no regular medication. Which of the following is most probably deficient?
Your Answer: C5
Explanation:Pneumococcal meningitis is the most common and severe form of bacterial meningitis. Fatality rates are substantial, and long-term sequelae develop in about half of survivors. Disease outcome has been related to the severity of the proinflammatory response in the subarachnoid space. The complement system, which mediates key inflammatory processes, has been implicated as a modulator of pneumococcal meningitis disease severity in animal studies. C5 fragment levels in cerebrospinal fluid (CSF) of patients with bacterial meningitis correlated with several clinical indicators of poor prognosis.
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This question is part of the following fields:
- Infectious Diseases
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Question 16
Correct
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A 4-year-old boy admitted with fever for 2 days had a left sided focal fits, which persisted for 4 minutes. There was no history of head injury. On examination, he was drowsy but there were no focal neurological signs. Urine dipstick was negative. What is the investigation of choice that can be done at this stage to arrive at a diagnosis?
Your Answer: CSF analysis
Explanation:This presentation could be due to either a meningitis or encephalitis, which are clinically not distinguishable from the given history. Encephalitis is mostly viral and in UK herpes simplex virus is the main cause. Advanced neuro imaging and EEG will help to differentiate them however from the given answers CSF analysis is the most appropriate, provided that intracranial pressure is not raised. CSF analysis will help to differentiate a pyogenic meningitis from other forms of meningitis and encephalitis.
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This question is part of the following fields:
- Infectious Diseases
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Question 17
Correct
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A urine culture of a 50-year-old patient with urosepsis has isolated a multi-drug resistant Escherichia coli. What is the most likely reason for the multidrug resistance?
Your Answer: Extended spectrum beta-lactamase (ESBL) production
Explanation:Extended-spectrum beta-lactamases (ESBL) are enzymes that confer resistance to most beta-lactam antibiotics, including penicillins, cephalosporins, and the monobactam aztreonam. Extended spectrum beta-lactamase (ESBL) production is the main reason for multi-drug resistance among E.coli. Commonly used medications to treat ESBL-involved infections include carbapenems (imipenem, meropenem, and doripenem), cephamycins (cefoxitin and cefotetan), Fosfomycin, nitrofurantoin, beta-lactamase inhibitors (clavulanic acid, tazobactam, or sulbactam), non-beta-lactamases and colistin (if all other medications have failed.)
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This question is part of the following fields:
- Infectious Diseases
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Question 18
Correct
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A 30-year-old man has been unwell for the last 3 weeks and now developed a rash. Chickenpox is diagnosed.
What is the appropriate treatment?Your Answer: Acyclovir
Explanation:You may treat chickenpox with acyclovir if it is commenced within the first 24 hours of the rash’s appearance. Erythromycin, doxycycline, and ampicillin would not help because it’s a viral infection (Varicella) not a bacterial infection.
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This question is part of the following fields:
- Infectious Diseases
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Question 19
Correct
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A 19-year-old male presented with a fever and fatigue. On examination, he had multiple lesions on his back and abdomen in various forms. Which of the following is the most probable diagnosis?
Your Answer: Varicella zoster
Explanation:Patients with varicella zoster infection present with general fatigue and fever along with multiple lesions which do not appear to be identical.
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This question is part of the following fields:
- Infectious Diseases
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Question 20
Incorrect
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Hepatitis C is what kind of virus?
Your Answer: A DNA virus
Correct Answer: A variable RNA virus
Explanation:Hepatitis C is a single-stranded positive sense RNA virus. It is variable because of the high rate of error of RNA-dependent RNA polymerase and the pressure from the host immune system has caused HCV to evolve and develop seven genetic lineages.
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This question is part of the following fields:
- Infectious Diseases
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Question 21
Correct
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Regarding neonatal meningitis, which of the following statements is true?
Your Answer: Has an above average incidence in babies with a meningomyelocele
Explanation:The commonest time for bacterial meningitis is in the 1st month of life and group B Streptococcus is the commonest organism. The anterior fontanelle is full, but does not bulge with normal flexion. Neurological manifestations include seizures, irritability, poor tone, lethargy and tremors, however no findings of sensorineural deafness have been noted. One of the risk factors for introduction of meningeal infection is Meningomyelocele.
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This question is part of the following fields:
- Infectious Diseases
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Question 22
Incorrect
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Which of the following drugs is NOT used in the treatment of MRSA?
Your Answer: Doxicycline
Correct Answer: Ceftriaxone
Explanation:Cephalosporins, such as ceftriaxone, do not cover methicillin-resistant staph aureus. They do cover some gram positives and gram negatives. Vancomycin and teicoplanin given intravenously have good coverage of MRSA and other gram positive bacteria. Rifampicin and doxycycline, although not the best treatment, can be used for outpatients if there are no systemic signs of illness.
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This question is part of the following fields:
- Infectious Diseases
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Question 23
Correct
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A 79-year-old nursing home resident presents to the clinic with an intensely itchy rash. Examination reveals white linear lesions on the wrists and elbows, and red papules on the penile surface. Which of the following will be the most suitable management plan for this patient?
Your Answer: Topical permethrin
Explanation:Scabies is a parasitic skin infestation caused by Sarcoptes scabiei mite, which is primarily transmitted via direct human-to-human contact. The female scabies mite burrows into the superficial skin layer, causing severe pruritus, particularly at night. Primary lesions commonly include erythematous papules, vesicles, or burrows. Treatment involves topical medical therapy (e.g. permethrin) and decontamination of all clothing and textiles.
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This question is part of the following fields:
- Infectious Diseases
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Question 24
Correct
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A 32-year-old Indian male presents to the clinic with fever, cough and an enlarged cervical lymph node. Examination reveals a caseating granuloma in the lymph node. Which of the following is the most likely diagnosis?
Your Answer: TB adenitis
Explanation:Tuberculous lymphadenitis is a chronic, specific granulomatous inflammation of the lymph node with caseation necrosis, caused by infection with Mycobacterium tuberculosis or a related bacteria. The characteristic morphological element is the tuberculous granuloma (caseating tubercle).
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This question is part of the following fields:
- Infectious Diseases
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Question 25
Correct
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A 45-year-old female presented with weight loss, night sweats and abdominal pain for 6 months. Abdominal ultrasound scan showed a tubo-ovarian mass. What is the most likely organism, which is responsible for this presentation?
Your Answer: Mycobacterium tuberculosis
Explanation:Constitutional symptoms such as weight loss, evening pyrexia and night sweats are associated with Mycobacterium Tuberculosis (TB). TB can affect any system of the body and should be top in the list of differentials particularly if the patient has a history of contact with a known TB patient.
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This question is part of the following fields:
- Infectious Diseases
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Question 26
Incorrect
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Which one of the following congenital infections is most characteristically associated with chorioretinitis?
Your Answer: Cytomegalovirus
Correct Answer: Toxoplasma gondii
Explanation:The common congenital infections encountered are rubella, toxoplasmosis and cytomegalovirus. Cytomegalovirus is the most common congenital infection in the UK. Maternal infection is usually asymptomatic.
Congenital toxoplasmosis is associated with fetal death and abortion, and in infants, it is associated with neurologic deficits, neurocognitive deficits, and chorioretinitis. -
This question is part of the following fields:
- Infectious Diseases
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Question 27
Incorrect
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A 55-year-old lady who a known case of normal pressure hydrocephalus (NPH) presented with complaints of weakness in her lower limbs, urinary incontinence and progressively worsening confusion. Which of the following statements is true regarding NPH?
Your Answer: Is not associated with raised intracranial pressure
Correct Answer: Is associated with gait disturbance
Explanation:Normal pressure hydrocephalus is a form of communicating hydrocephalus characterised by enlarged ventricles with normal opening pressure on lumbar puncture. For diagnostic purposes, a triad of urinary incontinence, gait abnormality and dementia is necessary. It is necessary to diagnose the condition early because it is reversible by placing a ventriculoperitoneal shunt. It is most common in patients aged more than 60 years.
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This question is part of the following fields:
- Infectious Diseases
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Question 28
Correct
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A man was admitted to the hospital and developed varicella zoster after 48h. Which of the following categories of people should be administered immunoglobulin only?
Your Answer: All pregnant women who are tested negative for antibodies.
Explanation:Immunoglobulin should be given to all seronegative women within 4 days. However, it is strongly advised to seek medical care immediately if the disease develops.
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This question is part of the following fields:
- Infectious Diseases
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Question 29
Correct
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A 35-year-old female presented with complaints of earache and a high-grade fever. During examination, numerous small vesicles were found within the ear canal and her ear is very tender. Which one of the following organisms is most likely to be responsible for such a condition?
Your Answer: Herpes zoster
Explanation:Herpes zoster is a viral disorder in which painful vesicular lesions are present in a specific dermatome area. High-grade fever may present as well due to infection. Varicella zoster, measles, herpes simplex and HIV do not present with tender lesions of a limited area.
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This question is part of the following fields:
- Infectious Diseases
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Question 30
Incorrect
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Which of the following procedures does not require antibiotic prophylaxis?
Your Answer: Emergency sigmoid colectomy
Correct Answer: Dental procedure for a patient with an atrial septal defect
Explanation:According to latest NICE guidelines, patients with isolated atrial septal defects do not require prophylactic antibiotics originally used in prevention of infective endocarditis in dental procedures.
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This question is part of the following fields:
- Infectious Diseases
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