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Question 1
Correct
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A 13-year-old girl takes a deliberate, unknown number of paracetamol tablets in one go. She immediately regrets her actions and calls for help.
She was brought to the hospital 2 hours after consuming the tablets. She has a history of HIV and is on antiretroviral therapy, though she cannot recall the name of the medication.
Which of the following management options is most appropriate for this patient?Your Answer: Check paracetamol level in further 2 hours' time
Explanation:In this scenario, the most appropriate management option for the 13-year-old girl who ingested an unknown number of paracetamol tablets is to check the paracetamol level in a further 2 hours’ time. This is because the Rumack-Matthew Nomogram, which is used to determine the risk of hepatotoxicity following paracetamol overdose, is most accurate between 4-15 hours post-ingestion. Checking the paracetamol level now would not provide an accurate assessment of the severity of the overdose.
It is important to note that the administration of N-acetylcysteine (NAC) can be delayed until the 4-hour level is obtained and compared to the nomogram. Haemodialysis is only indicated in cases of hepatorenal syndrome, which typically occurs 72-96 hours post-ingestion. Acute liver transplantation is considered in cases of severe liver damage, such as persistent acidosis, hepatorenal syndrome, and worsening coagulopathy.
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This question is part of the following fields:
- Clinical Evaluation
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Question 2
Incorrect
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A 3 month old infant born to HIV positive mother presented with jaundice, epileptic seizures and microcephaly. The most likely cause will be?
Your Answer: Varicella
Correct Answer: Cytomegalovirus
Explanation:Congenital cytomegalovirus (CMV) infection is a common viral infection that can be passed from a mother to her baby during pregnancy. Infants born with congenital CMV infection may present with a variety of symptoms, including jaundice, hepatosplenomegaly (enlargement of the liver and spleen), petechiae (small red or purple spots on the skin), microcephaly (abnormally small head size), hearing loss, and seizures.
In this case, the 3-month-old infant born to an HIV positive mother presented with jaundice, epileptic seizures, and microcephaly. Given these symptoms, the most likely cause would be congenital cytomegalovirus infection. Other viral infections such as Epstein-Barr virus, measles, rubella, and varicella can also cause similar symptoms, but the combination of jaundice, seizures, and microcephaly is most commonly associated with CMV infection.
It is important to diagnose and manage congenital CMV infection early to prevent long-term complications such as hearing loss and developmental delays. Testing for CMV infection can be done through blood tests, urine tests, or saliva tests. Treatment may include antiviral medications and supportive care to manage symptoms.
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This question is part of the following fields:
- Microbiology
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Question 3
Correct
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A 52-year-old man visits his GP with complaints of burning during urination and swelling in the groin area. He also reports experiencing penile discharge and pain in the groin. He has been sexually active with his wife for the past 6 years.
During the examination, his heart rate is 91/min, respiratory rate is 15/min, blood pressure is 129/84 mmHg, and temperature is 38.3ºC. The patient experiences pain in his right testicle, which is relieved by elevating the scrotum.
What is the most likely organism responsible for his symptoms?Your Answer: Escherichia coli
Explanation:Epididymo-orchitis in individuals with a low risk of sexually transmitted infections (such as a married male in his 50s with only one sexual partner, his wife) is most likely caused by enteric organisms, specifically Escherichia coli. This is evidenced by the patient’s symptoms of unilateral testicular pain, tenderness, and swelling, as well as dysuria and relief of pain when the testicle is raised. While Enterococcus faecalis is also a possible causative organism, E. coli is more common in older patients with low-risk sexual histories. Chlamydia trachomatis and Neisseria gonorrhoeae are less likely causes, as they are more commonly associated with epididymo-orchitis in younger patients with high-risk sexual histories.
Epididymo-orchitis is a condition where the epididymis and/or testes become infected, leading to pain and swelling. It is commonly caused by infections spreading from the genital tract or bladder, with Chlamydia trachomatis and Neisseria gonorrhoeae being the usual culprits in sexually active younger adults, while E. coli is more commonly seen in older adults with a low-risk sexual history. Symptoms include unilateral testicular pain and swelling, with urethral discharge sometimes present. Testicular torsion, which can cause ischaemia of the testicle, is an important differential diagnosis and needs to be excluded urgently, especially in younger patients with severe pain and an acute onset.
Investigations are guided by the patient’s age, with sexually transmitted infections being assessed in younger adults and a mid-stream urine (MSU) being sent for microscopy and culture in older adults with a low-risk sexual history. Management guidelines from the British Association for Sexual Health and HIV (BASHH) recommend ceftriaxone 500 mg intramuscularly as a single dose, plus doxycycline 100 mg orally twice daily for 10-14 days if the organism causing the infection is unknown. Further investigations are recommended after treatment to rule out any underlying structural abnormalities.
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This question is part of the following fields:
- Microbiology
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Question 4
Incorrect
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Which of the following pairing is correct:
Your Answer: Herpes simplex type I and primary genital herpes
Correct Answer: Herpes simplex type I and herpes encephalitis
Explanation:The correct pairing is Herpes simplex type I and herpes encephalitis.
Herpes simplex virus type I is known to cause herpes encephalitis, which is a rare but serious infection of the brain. This condition can lead to inflammation of the brain, seizures, and even death if not treated promptly.
The other pairings are incorrect because they do not match the specific viruses with the corresponding diseases. For example, Human herpesvirus type 7 is not associated with Kaposi’s Sarcoma, and Human herpesvirus type 8 is not associated with Roseola infantum. It is important to correctly match the virus with the disease in order to understand the causes and treatments for each condition.
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This question is part of the following fields:
- Microbiology
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Question 5
Incorrect
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Which of the following drugs is NOT bacteriostatic?
Your Answer: Chloramphenicol
Correct Answer: Penicillin
Explanation:Bacteriostatic antibiotics work by inhibiting the growth or reproduction of bacteria, while bactericidal antibiotics work by directly killing bacteria. In this case, Penicillin is a bactericidal antibiotic because it inhibits cell wall synthesis, leading to bacterial cell death. Tetracycline, Erythromycin, and Sulphonamides are bacteriostatic antibiotics because they slow down bacterial growth or reproduction. Chloramphenicol is also primarily bacteriostatic, although it can exhibit bactericidal action in high concentrations. Therefore, the correct answer to the question is Penicillin.
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This question is part of the following fields:
- Pharmacology
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Question 6
Correct
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For PMTCT, when is an HIV PCR test done for neonates born to HIV-positive mothers?
Your Answer: At birth or immediately for high-risk mothers.
Explanation:For Prevention of Mother-to-Child Transmission (PMTCT) of HIV, it is crucial to identify HIV infection in newborns as early as possible in order to start treatment promptly and prevent the progression of the disease. Therefore, an HIV PCR test is done for neonates born to HIV-positive mothers at birth or immediately for high-risk mothers.
The option At one year of age is not ideal because delaying the test until one year of age can result in missed opportunities for early intervention and treatment. The option Only if the mother was not on ART during pregnancy is not accurate because all newborns born to HIV-positive mothers should be tested regardless of the mother’s ART status. The option At six weeks during vaccinations is not the recommended timing for the HIV PCR test. The option At nine months is also not the recommended timing for the test.
In conclusion, conducting an HIV PCR test at birth or immediately for babies born to high-risk mothers is essential for early detection and management of HIV infection in newborns.
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This question is part of the following fields:
- Epidemiology
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Question 7
Incorrect
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A 34-year-old HIV positive man is referred to gastroenterology due to jaundiced sclera. Liver function tests are as follows:
Albumin 34 g/l
ALP 540 iu/l
Bilirubin 67 µmol/l
ALT 45 iu/l
What is the most likely diagnosis?Your Answer: Primary biliary cirrhosis
Correct Answer: Sclerosing cholangitis
Explanation:The most likely diagnosis for this 34-year-old HIV positive man with jaundiced sclera and abnormal liver function tests is primary sclerosing cholangitis. This is because HIV can cause strictures in the biliary tract, leading to inflammation and scarring of the bile ducts. The elevated ALP and bilirubin levels, along with the presence of jaundiced sclera, are consistent with this diagnosis.
Sclerosing cholangitis is a chronic liver disease characterized by inflammation and scarring of the bile ducts, leading to obstruction of bile flow. This can result in symptoms such as jaundice, fatigue, and itching. The liver function tests in this case show elevated ALP and bilirubin levels, which are indicative of cholestasis (impaired bile flow).
While other conditions such as hepatic abscess, fungal obstruction of the bile duct, duodenal adenoma, and primary biliary cirrhosis can also present with jaundice and abnormal liver function tests, the association of HIV with strictures in the biliary tract makes primary sclerosing cholangitis the most likely diagnosis in this case. It is important to consider the patient’s HIV status and the potential complications associated with the disease when making a diagnosis.
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This question is part of the following fields:
- Pathology
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Question 8
Incorrect
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A 20-year-old woman visits her GP complaining of discharge. She mentions having a recent sexual partner without using barrier protection. During the examination, the doctor observes thick cottage-cheese-like discharge. The patient denies experiencing any other notable symptoms. What is the probable diagnosis?
Your Answer: Chlamydia
Correct Answer: Candida albicans
Explanation:Vaginal candidiasis, also known as thrush, is a common condition that many women can diagnose and treat themselves. Candida albicans is responsible for about 80% of cases, while other candida species cause the remaining 20%. Although most women have no predisposing factors, certain factors such as diabetes mellitus, antibiotics, steroids, pregnancy, and HIV can increase the likelihood of developing vaginal candidiasis. Symptoms include non-offensive discharge resembling cottage cheese, vulvitis, itching, vulvar erythema, fissuring, and satellite lesions. A high vaginal swab is not routinely indicated if the clinical features are consistent with candidiasis. Treatment options include local or oral therapy, with oral fluconazole 150 mg as a single dose being the first-line treatment according to NICE Clinical Knowledge Summaries. If there are vulval symptoms, a topical imidazole may be added to an oral or intravaginal antifungal. Pregnant women should only use local treatments. Recurrent vaginal candidiasis is defined as four or more episodes per year by BASHH. Compliance with previous treatment should be checked, and a high vaginal swab for microscopy and culture should be performed to confirm the diagnosis. A blood glucose test may be necessary to exclude diabetes, and differential diagnoses such as lichen sclerosus should be ruled out. An induction-maintenance regime involving oral fluconazole may be considered. Induction involves taking oral fluconazole every three days for three doses, while maintenance involves taking oral fluconazole weekly for six months.
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This question is part of the following fields:
- Microbiology
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Question 9
Incorrect
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A 55-year-old woman comes to the clinic with blisters on her skin. She reports that some of the blisters have healed and left scars, but others are still growing and new ones are appearing. Despite taking antibiotics prescribed by her primary care physician, the blisters have not improved. Upon examination, the patient has multiple superficial skin lesions and oral lesions that easily slough off. A skin punch biopsy with immunofluorescent examination reveals circular intra-epidermal deposits. What other symptoms may this patient be experiencing?
Your Answer: Alopecia
Correct Answer: Antibodies against desmosomes
Explanation:Understanding Pemphigus Vulgaris: An Autoimmune Blistering Condition
Pemphigus vulgaris is a blistering condition that primarily affects middle-aged individuals. It is caused by IgG autoantibodies against desmosomal components, specifically desmogleins 1 and 3, in the superficial layers of the skin. This results in flaccid blisters that easily rupture, leading to erosions and scarring. The oral mucosa is often affected early on, and Nikolsky’s sign is positive. Immunofluorescence reveals intra-epidermal circular deposits, and antibodies against desmosomes are typically positive. Treatment involves high-dose steroids and may require life-long maintenance doses. In contrast, bullous pemphigoid, which affects older individuals, is characterized by antibodies against hemidesmosomes in the deeper basement membrane of the skin, resulting in tense, firm blisters that do not rupture easily. Psoriasis, alopecia, and HIV are not linked to pemphigus vulgaris.
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This question is part of the following fields:
- Pathology
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Question 10
Correct
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A 32-year-old man visits the sexual health clinic following unprotected sex with a female partner. He reports experiencing coryzal symptoms and myalgia, which began four weeks ago. The patient has a history of asthma, which is managed with salbutamol. The doctor advises him to undergo HIV testing, and he consents. What is the best course of action for managing his condition?
Your Answer: Order HIV p24 antigen and HIV antibody tests
Explanation:The recommended course of action is to order a combination test for HIV p24 antigen and HIV antibody. The patient is exhibiting symptoms of HIV seroconversion and had unprotected intercourse 4 weeks ago. Combination tests are now the standard for HIV diagnosis and screening, with p24 antigen tests typically turning positive between 1 and 4 weeks post-exposure and antibody tests turning positive between 4 weeks and 3 months post-exposure. If a patient at risk tests positive, the diagnosis should be confirmed with a repeat test before starting treatment.
Offering post-exposure prophylaxis is not appropriate in this case, as the patient had unprotected intercourse 3 weeks ago. Two NRTIs and an NNRTI should not be prescribed as treatment, as the patient has not yet tested positive. Ordering only a p24 antigen or antibody test alone is also not recommended, as combination tests are now standard practice.
Understanding HIV Seroconversion and Diagnosis
HIV seroconversion is a process where the body develops antibodies to the HIV virus after being infected. This process is symptomatic in 60-80% of patients and usually presents as a glandular fever type illness. Symptoms may include sore throat, lymphadenopathy, malaise, myalgia, arthralgia, diarrhea, maculopapular rash, mouth ulcers, and rarely meningoencephalitis. The severity of symptoms is associated with a poorer long-term prognosis and typically occurs 3-12 weeks after infection.
Diagnosing HIV involves testing for HIV antibodies, which may not be present in early infection. However, most people develop antibodies to HIV at 4-6 weeks, and 99% do so by 3 months. The diagnosis usually consists of both a screening ELISA test and a confirmatory Western Blot Assay. Additionally, a p24 antigen test may be used to detect a viral core protein that appears early in the blood as the viral RNA levels rise. Combination tests that test for both HIV p24 antigen and HIV antibody are now standard for the diagnosis and screening of HIV. If the combined test is positive, it should be repeated to confirm the diagnosis. Testing for HIV in asymptomatic patients should be done at 4 weeks after possible exposure, and after an initial negative result, a repeat test should be offered at 12 weeks.
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This question is part of the following fields:
- Clinical Evaluation
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Question 11
Correct
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What proportion of HIV infections worldwide are caused by HIV-1?
Your Answer: Most
Explanation:HIV-1 is the most common and widespread type of the HIV virus, responsible for the majority of HIV infections worldwide. It is estimated that around 95% of all HIV infections are caused by HIV-1. This particular strain of the virus is more easily transmitted and progresses more rapidly to AIDS compared to HIV-2, which is less common and mainly found in West Africa.
The predominance of HIV-1 in the global HIV/AIDS epidemic is due to its higher transmission rates and ability to adapt and evolve rapidly. This has made it more challenging to develop effective vaccines and treatments against HIV-1 compared to HIV-2.
Overall, understanding the prevalence of HIV-1 is crucial for public health efforts to prevent and control the spread of HIV/AIDS worldwide. By focusing on strategies to target HIV-1 transmission and treatment, we can work towards reducing the impact of the virus on global health.
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This question is part of the following fields:
- Epidemiology
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Question 12
Correct
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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 this case, the most suitable investigation would be a stool culture and sensitivity. This is because the patient is presenting with symptoms of bloody and mucoid diarrhea, which could be indicative of a bacterial or parasitic infection. A stool culture and sensitivity test would help identify the specific organism causing the infection and determine the most effective antibiotic treatment.
Colonoscopy and biopsy may be considered if the symptoms persist or if there are other concerning findings, but it is not the initial investigation of choice in this case. IgA against tissue transglutaminase is a test used to diagnose celiac disease, which does not typically present with bloody diarrhea. Barium meal and jejunal biopsy are not typically indicated for the symptoms described.
Therefore, in this case, a stool culture and sensitivity test would be the most appropriate investigation to determine the cause of the bloody and mucoid diarrhea and guide treatment.
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This question is part of the following fields:
- Microbiology
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Question 13
Correct
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Regarding hepatitis C, which of the following statements is INCORRECT:
Your Answer: Anti-HCV IgG antibodies are diagnostic of acute infection.
Explanation:Anti-HCV IgG antibodies indicate exposure to hepatitis C but this could be acute, chronic or resolved infection. If the antibody test is positive, HCV RNA should be tested for, which if positive indicates that a person has current infection with active hepatitis C.
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This question is part of the following fields:
- Microbiology
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Question 14
Incorrect
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A 12-year-old boy presented with jaundice and fatigue for the last two weeks. He complains of intermittent pain in his epigastrium.
He is otherwise healthy with no history of vomiting, diarrhoea, loss of appetite or weight.
History revealed that he has had fatigue all his life leading to him missing out on sports at regular intervals at school.
His mother reports that he had two episodes of hepatitis at ages 5 and 7 years. There is no family history of jaundice. He has no significant travel history.
On physical examination, yellow sclera were observed. Additionally, on abdominal examination, the splenic tip was palpable at 3 cm with some tenderness of the right upper quadrant. He was found to have mild tachycardia with normal blood pressure and no fever.
Blood results:
- Hb: 12.6 g/dl
- MCV: 104 fL
- MCHC: 38 g/dL
- WBC Count: 10 x 109/L
- Reticulocyte count: 148 x 109/L (Normal Range 20-100 x 109/L)
- Bilirubin: 34 μmol/L
- LDH: 600 lμ/L (Normal Range 230-450 lμ/l)
- Direct Coombs test: Negative
Abdominal ultrasonography revealed an enlarged spleen measuring 15 cm
What is the most probable diagnosis?Your Answer: Acquired autoimmune haemolytic anaemia (AIHA)
Correct Answer: Hereditary spherocytosis
Explanation:The most probable diagnosis in this case is hereditary spherocytosis. This conclusion is based on the patient’s presentation of jaundice, fatigue, and abdominal pain, along with a history of chronic fatigue and previous episodes of hepatitis. The absence of fever and travel history to endemic areas makes acute hepatitis and cholecystitis less likely.
The blood results showing low hemoglobin levels, high MCV, high reticulocyte count, and elevated LDH also point towards a chronic hemolytic anemia. The negative Coombs test rules out autoimmune hemolytic anemia, leaving hereditary spherocytosis as the most likely cause.
Hereditary spherocytosis is a genetic disorder that causes red blood cells to be more fragile, leading to their destruction and resulting in anemia. Splenomegaly and gallstones are common complications of this condition due to increased red cell destruction and hemoglobin metabolism. Abdominal ultrasound showing an enlarged spleen further supports the diagnosis of hereditary spherocytosis.
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This question is part of the following fields:
- Clinical Evaluation
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Question 15
Correct
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An HIV positive woman who is 18 weeks pregnant complains of frothy yellow vaginal discharge and vaginal soreness. A wet mount and microscopy confirms a Trichomonas vaginalis infection. Which of the following is the most appropriate treatment regime?
Your Answer: Metronidazole 500mg BD 7 days
Explanation:In the case of diagnostic testing, detection of C. trachomatis, N. gonorrhoeae and Trichomonas vaginalis should be done using a nucleic acid amplification test (NAAT) using first-void urine in men and, in women, a self-collected or healthcare-worker-collected vulvovaginal or endocervical swab. In some specific situations, collection of first-void urine may provide an alternative option to a vaginal swab; however, a vaginal swab is the preferred specimen as the yield is higher than with urine in women.
In the absence of diagnostic tests, syndromic treatment (i.e. empirical antimicrobial treatment that covers the most likely aetiology of the syndrome that the patient presents with) should be provided and patients instructed to return for further management if there is not resolution of symptoms.
Given the high burden of STIs in Southern Africa, the syndromic treatment regimen of VDS should cover C. trachomatis, N. gonorrhoeae and T. vaginalis infection in sexually active women. The recommended empirical regimen is azithromycin, ceftriaxone, and metronidazole.
The most appropriate treatment regime for a pregnant HIV positive woman with a Trichomonas vaginalis infection is metronidazole 500mg twice daily for 7 days. A 7-day course of metronidazole is preferred over single-dose treatment as it has a higher efficacy for the treatment of T. vaginalis and, if present, the added benefit of treating concurrent BV. However, single-dose metronidazole may be used in certain populations and settings based on the benefits of same-day and observed therapy, and medication availability.
It is important to treat both the pregnant woman and her sexual partners to prevent reinfection. Additionally, screening for other sexually transmitted infections should be carried out to ensure comprehensive care for the patient.
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This question is part of the following fields:
- Microbiology
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Question 16
Correct
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A 72-year-old woman who presented with headache and neck stiffness was started on IV ceftriaxone after undergoing a lumbar puncture. The CSF culture shows listeria monocytogenes. What is the treatment of choice?
Your Answer: Change to IV amoxicillin + gentamicin
Explanation:Listeria monocytogenes is a bacterium that can cause serious infections, particularly in immunocompromised individuals and the elderly. When treating listeria meningitis, the treatment of choice is a combination of ampicillin and gentamicin. Ampicillin is effective against listeria monocytogenes, while gentamicin is added to provide synergistic activity and improve outcomes.
In this case, the patient was initially started on IV ceftriaxone, which is not the optimal treatment for listeria monocytogenes. Therefore, the best course of action would be to change the antibiotic regimen to IV ampicillin and gentamicin. This combination therapy has been shown to be effective in treating listeria meningitis and reducing mortality rates.
The other options provided, such as IV amoxicillin, IV ciprofloxacin, IV co-amoxiclav, and continuing IV ceftriaxone as monotherapy, are not recommended for the treatment of listeria monocytogenes. It is important to promptly switch to the appropriate antibiotics to ensure the best possible outcome for the patient.
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This question is part of the following fields:
- Microbiology
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Question 17
Correct
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A 35-year-old man presents with haemoptysis, night sweats, and weight loss. Further examinations were done and a diagnosis of tuberculosis is suspected.
Which of the following statements is considered correct regarding Mycobacterium tuberculosis?Your Answer: It is impervious to decolourisation with acid
Explanation:Mycobacterium tuberculosis is a bacterium that causes tuberculosis, a contagious infection that usually affects the lungs. One of the key characteristics of Mycobacterium tuberculosis is its resistance to decolorization with acid, making it difficult to stain and identify using traditional methods like Gram staining.
Scrofula refers to extrapulmonary tuberculosis that affects the lymph nodes, particularly those in the neck. It is not specifically related to spinal tuberculosis.
Approximately 90% of patients infected with Mycobacterium tuberculosis will develop latent tuberculosis infection, where the bacteria are present in the body but not causing symptoms. Only a small percentage of these individuals will go on to develop active tuberculosis disease.
The Ghon focus is a characteristic lesion seen in primary tuberculosis infection, typically appearing at the base of the lower lobe of the lung. It consists of a small area of consolidation and lymphadenopathy.
Overall, Mycobacterium tuberculosis is a highly infectious bacterium that can cause serious health complications if left untreated. Early detection and appropriate treatment are essential in managing tuberculosis and preventing its spread to others.
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This question is part of the following fields:
- Microbiology
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Question 18
Incorrect
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A 24 year old woman presents to the clinic with foul smelling vaginal discharge. Which facultative anaerobic bacteria is most likely to be the cause?
Your Answer: Neisseria gonorrhoeae
Correct Answer: Gardnerella vaginalis
Explanation:Bacterial vaginosis is a common infection in women that is caused by an overgrowth of atypical bacteria in the vagina. The most common causative agent of bacterial vaginosis is Gardnerella vaginalis, which is a facultative anaerobic bacteria. This means that Gardnerella vaginalis can survive in both oxygen-rich and oxygen-poor environments.
When a woman presents with symptoms of bacterial vaginosis, such as foul-smelling vaginal discharge, Gardnerella vaginalis is the most likely culprit. Other symptoms of bacterial vaginosis may include itching, burning, and irritation in the vaginal area.
In diagnosing bacterial vaginosis, a healthcare provider may take a swab of the vaginal discharge for microscopy. Clue cells, which are vaginal epithelial cells covered in bacteria, are often seen under the microscope in cases of bacterial vaginosis.
It is important to differentiate bacterial vaginosis from other sexually transmitted infections, such as Chlamydia trachomatis, Neisseria gonorrhoeae, and Treponema pallidum. These organisms have different characteristics and require different treatment approaches.
In conclusion, when a 24-year-old woman presents with foul-smelling vaginal discharge, Gardnerella vaginalis is the most likely cause, and bacterial vaginosis should be considered as a possible diagnosis.
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This question is part of the following fields:
- Microbiology
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Question 19
Correct
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A 6-year-old boy with fever and malaise for 2 days recently developed bloody diarrhoea. What is the most probable aetiology?
Your Answer: Escherichia coli 0157
Explanation:The most probable etiology for the 6-year-old boy’s symptoms of fever, malaise, and bloody diarrhea is Escherichia coli 0157. This particular strain of E. coli, known as enterohemorrhagic verotoxin-producing E. coli, is known to cause bloody diarrhea and can lead to complications such as hemolytic uremic syndrome.
Crohn’s disease is unlikely in this case as it typically presents with chronic symptoms rather than an acute onset. Polio and giardiasis are also less likely as they typically present with non-bloody diarrhea.
Overall, given the symptoms described, E. coli 0157 is the most probable cause of the boy’s illness.
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This question is part of the following fields:
- Microbiology
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Question 20
Incorrect
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A 33-year-old lady who is known hepatitis C positive comes to your clinic. She is 28 weeks pregnant and her obstetrician wants you to assess her and provide medical advice for the mother and child.
Which of the following statements concerning hepatitis C are most accurate in her case?Your Answer: A high viral load at delivery increases the risk of transmission
Correct Answer: Breast-feeding does not increase the risk of transmission
Explanation:Hepatitis C is a viral infection that can be transmitted from mother to baby during pregnancy or childbirth. In the case of the 33-year-old pregnant lady who is hepatitis C positive, it is important to provide accurate information and advice to ensure the health of both the mother and the baby.
Breastfeeding does not increase the risk of transmission of hepatitis C from mother to baby. This is an important fact to remember when counseling the mother.
Co-infection with HIV does increase the risk of transmission of hepatitis C from mother to baby. It is important to monitor and manage both infections in this case.
A high viral load at delivery does increase the risk of transmission of hepatitis C from mother to baby. Close monitoring and appropriate management are necessary in this situation.
Mother to baby transmission of hepatitis C is estimated to be around 5-15%. It is important to provide accurate information about the risk of transmission to the mother.
There is no evidence to suggest that elective Caesarean section reduces the risk of transmission of hepatitis C from mother to baby. It is important to focus on monitoring and managing the infection during pregnancy and childbirth.
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This question is part of the following fields:
- Epidemiology
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Question 21
Incorrect
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A 25-year-old woman visits her primary care physician (PCP) complaining of yellow vaginal discharge, abnormal vaginal odor, vulvar itching, and pain while urinating. During the examination, the PCP notices a purulent discharge and a patchy erythematous lesion on the cervix. The PCP suspects Trichomonas vaginalis as the possible diagnosis. What would be the most suitable investigation to assist in the diagnosis of T. vaginalis for this patient?
Your Answer: Cervical swab
Correct Answer: Wet mount and high vaginal swab
Explanation:Trichomoniasis is a sexually transmitted disease caused by the protozoan parasite T. vaginalis. While both men and women can be affected, women are more likely to experience symptoms. Diagnosis of trichomoniasis is typically made through wet mount microscopy and direct visualisation, with DNA amplification techniques offering higher sensitivity. Urine testing is not considered the gold standard, and cervical swabs are not sensitive enough. Treatment involves a single dose of metronidazole, and sexual partners should be treated simultaneously. Trichomoniasis may increase susceptibility to HIV infection and transmission. Symptoms in women include a yellow-green vaginal discharge with a strong odour, dysuria, pain on intercourse, and vaginal itching. Men may experience penile irritation, mild discharge, dysuria, or pain after ejaculation.
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This question is part of the following fields:
- Microbiology
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Question 22
Incorrect
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For neonates born to HIV-positive mothers, what is the recommended antiretroviral therapy (ART) regimen from birth to less than 4 weeks of age and weighing ≥ 3.0 kg?
Your Answer: Tenofovir disoproxil fumarate-Lamivudine-Dolutegravir
Correct Answer: Zidovudine-Lamivudine-Nevirapine
Explanation:Neonates born to HIV-positive mothers are at risk of acquiring the virus during childbirth or through breastfeeding. To prevent mother-to-child transmission of HIV, it is crucial to provide antiretroviral therapy (ART) to these neonates as soon as possible after birth.
For neonates born to HIV-positive mothers from birth to less than 4 weeks of age and weighing ≥ 3.0 kg, the recommended ART regimen is Zidovudine (AZT) + Lamivudine (3TC) + Nevirapine (NVP). This combination of antiretroviral drugs has been shown to be effective in reducing the risk of HIV transmission from mother to child.
Zidovudine (AZT) and Lamivudine (3TC) are nucleoside reverse transcriptase inhibitors (NRTIs) that work by inhibiting the replication of the HIV virus. Nevirapine (NVP) is a non-nucleoside reverse transcriptase inhibitor (NNRTI) that also helps to prevent the virus from multiplying in the body.
By starting ART early in neonates born to HIV-positive mothers, healthcare providers can significantly reduce the risk of HIV transmission and improve the long-term health outcomes of these infants. It is important for healthcare providers to closely monitor the neonates on this ART regimen and adjust the treatment as needed based on their individual health status.
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This question is part of the following fields:
- Pharmacology
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Question 23
Correct
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By what mechanism do retroviruses, including HIV, replicate?
Your Answer: Reverse transcription
Explanation:Retroviruses, such as HIV, replicate through a unique mechanism known as reverse transcription. This process involves the conversion of the virus’s RNA genome into DNA copies, which can then integrate into the host cell’s genome.
Binary fission is a method of asexual reproduction in which a cell divides into two identical daughter cells, commonly seen in bacteria and some single-celled organisms. This process is not used by retroviruses for replication.
Budding is a method of viral replication in which new virus particles are released from the host cell by taking a portion of the cell membrane with them. While some viruses, like the influenza virus, replicate through budding, retroviruses like HIV do not use this mechanism.
The lytic cycle is a method of viral replication in which the virus infects a host cell, replicates within the cell, and then causes the cell to burst, releasing new virus particles. Retroviruses do not replicate through the lytic cycle.
Transformation is a process by which a cell takes up foreign DNA from its surroundings and incorporates it into its own genome. This mechanism is not used by retroviruses for replication.
In conclusion, retroviruses, including HIV, replicate through reverse transcription, which involves copying RNA into DNA copies that integrate into the host cell’s genome.
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This question is part of the following fields:
- Microbiology
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Question 24
Correct
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Which factor does NOT significantly impact the prognosis of an HIV-infected individual?
Your Answer: Dietary habits
Explanation:The prognosis of an HIV-infected individual is primarily determined by their CD4 count and plasma HIV RNA levels. These factors indicate the progression of the disease and the effectiveness of treatment. Geographic location can also play a role in prognosis, as access to healthcare and treatment options may vary. Economic status can impact prognosis indirectly, as individuals with lower economic status may have less access to healthcare and resources. Genetic makeup can also influence how the body responds to the virus and treatment. However, dietary habits are not a significant factor in determining the prognosis of an HIV-infected individual. While a healthy diet can support overall health and immune function, it is not a direct determinant of HIV progression.
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This question is part of the following fields:
- Epidemiology
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Question 25
Correct
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A patient in the first trimester of pregnancy has just learned that her husband has acute hepatitis B. She feels well, and her screening test for hepatitis B surface antigen (HBsAg) was negative last month. She has not been immunized against hepatitis B.
Which one of the following would be the most appropriate management of this patient?Your Answer: Administration of both HBIG and hepatitis B vaccine now
Explanation:This question presents a scenario where a pregnant woman has just learned that her husband has acute hepatitis B. The woman herself tested negative for hepatitis B surface antigen (HBsAg) last month and has not been immunized against hepatitis B.
The most appropriate management of this patient would be the administration of both hepatitis B immune globulin (HBIG) and hepatitis B vaccine now. This is because HBIG should be administered as soon as possible to patients with known exposure to hepatitis B. Additionally, the hepatitis B vaccine is a killed-virus vaccine that can be safely used in pregnancy, with no need to wait until after organogenesis.
The other answer choices are not as appropriate:
– No further workup or immunization at this time, a repeat HBsAg test near term, and treatment of the newborn if the test is positive: This approach does not address the immediate need for treatment and prevention of hepatitis B transmission to the mother.
– Use of condoms for the remainder of the pregnancy, and administration of immunization after delivery: Condoms may not be effective in preventing transmission of hepatitis B, and delaying immunization until after delivery may put the mother and newborn at risk.
– Testing for hepatitis B immunity (anti-HBs), and immunization if needed: Given the patient’s lack of history of hepatitis B infection or immunization, it is unlikely that she is immune to hepatitis B. Immediate treatment is needed in this scenario. -
This question is part of the following fields:
- Clinical Evaluation
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Question 26
Correct
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Her parents with a severe headache present a 24-year-old woman. She is afraid of light and sun and prefers darker environments. On examination, a generalized rash that does not blanch on pressure is noticed. What is the best action in this case?
Your Answer: IV benzylpenicillin
Explanation:In this case, the best action is to administer IV benzylpenicillin. The patient presents with a severe headache, photophobia, and a non-blanching rash, which are all indicative of meningitis. Meningitis is a serious infection of the protective membranes covering the brain and spinal cord, and requires immediate treatment with antibiotics to prevent complications such as brain damage or death.
Isolating the patient, gowning and masking, and performing a blood culture are important steps in preventing the spread of infection and determining the specific cause of the meningitis. However, the most urgent action in this case is to start IV antibiotics to treat the infection and reduce the risk of serious complications.
A CT Head may be ordered to further evaluate the patient’s symptoms and confirm the diagnosis of meningitis, but starting IV antibiotics should not be delayed while waiting for imaging results. Early treatment is crucial in cases of suspected meningitis to improve outcomes and prevent long-term complications.
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This question is part of the following fields:
- Clinical Evaluation
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Question 27
Correct
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A 14-month-old girl who was diagnosed with HIV at 8 weeks of age has been taking antiretroviral therapy and Pneumocystis pneumonia prophylaxis since the time HIV was diagnosed. She achieved an undetectable HIV RNA 4 weeks after starting antiretroviral therapy and has maintained suppressed HIV RNA levels since that time. Her recent laboratory studies showed an undetectable HIV RNA level, an absolute CD4 count of 812 cells/mm3, and a CD4 percentage of 26%.
Which one of the following should be recommended regarding Pneumocystis pneumonia prophylaxis?Your Answer: It can be stopped now
Explanation:All infants with HIV who are taking Pneumocystis pneumonia prophylaxis should continue the prophylaxis until age 1 year and then undergo reassessment for the need for prophylaxis. For children with HIV who are older than 1 year of age, discontinuing Pneumocystis pneumonia prophylaxis should be considered if the child meets the following two criteria:
They have received combination antiretroviral therapy for at least 6 months
They have surpassed the original age-specific CD4 count and percentage threshold for initiating prophylaxis and maintained above that threshold for at least 3 consecutive months.
For children who do not have virologic suppression, the CD4 count and percentage should be reassessed every 3 months, and prophylaxis should be restarted if the age-specific threshold for prophylaxis is once again met. -
This question is part of the following fields:
- Clinical Evaluation
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Question 28
Correct
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A 40-year-old man with known human immunodeficiency virus (HIV) presents to the Emergency Department with a 3-day history of worsening shortness of breath. He also has a fever and mentions the presence of a non-productive cough which has been getting worse over the past week.
On examination, the patient is febrile with a temperature of 38.2 oC, pulse is 92 bpm and regular, and his blood pressure is 110/85 mmHg.
The patient seems breathless at rest, with an oxygen saturation of 96% in room air. However, a chest examination reveals no abnormalities. The examining doctor orders tests, including a CD4 count, arterial blood gases (ABGs), and a chest X-ray; she lists Pneumocystis jirovecii pneumonia (PJP) as one of the possible differential diagnoses.
With regard to PJP, which of the following statements is true?Your Answer: Can be successfully treated with co-trimoxazole
Explanation:Understanding Pneumocystis Jirovecii Pneumonia (PJP)
Pneumocystis jirovecii pneumonia (PJP) is a fungal infection that primarily affects individuals with weakened immune systems. It is commonly seen in HIV patients with a CD4 count of less than 200, but can also occur in other immunosuppressive states. Symptoms include fever, dry cough, and progressive shortness of breath. Diagnosis can be challenging, and a high level of suspicion is required. While an abnormal chest radiograph is present in 90% of patients, blood culture is not a reliable diagnostic tool as pneumocystis cannot be cultured. Treatment involves the use of co-trimoxazole or pentamidine. Prophylaxis against PJP is recommended when CD4 counts fall below 200 cells/µl. It is important to note that while PJP is more common in HIV patients, it can also occur in individuals with other immunocompromising conditions.
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This question is part of the following fields:
- Microbiology
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Question 29
Incorrect
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What should be done if a pregnant woman on efavirenz (EFV)-based ART wishes to switch to a dolutegravir (DTG)-based regimen?
Your Answer: Switch after counseling, if the woman's most recent viral load in the last six months is <50 c/ml
Correct Answer:
Explanation:The reason for switching a pregnant woman on EFV-based ART to a DTG-based regimen after counseling and confirming a viral load of <50 c/ml in the last six months is due to the potential risks associated with EFV during pregnancy. EFV has been associated with an increased risk of neural tube defects in the fetus, particularly when taken in the first trimester of pregnancy. DTG, on the other hand, has shown to be safe and effective in pregnancy with no increased risk of birth defects. Therefore, it is recommended to switch to a DTG-based regimen in order to minimize the potential risks to the fetus. Counseling is important to ensure that the woman understands the reasons for the switch and is informed about the potential benefits and risks of the new regimen. Additionally, confirming a viral load of <50 c/ml ensures that the woman's HIV is well-controlled before making the switch, which is important for both her health and the health of the fetus.
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This question is part of the following fields:
- Pharmacology
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Question 30
Incorrect
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Which of the following diseases correctly matches the incubation period?
Your Answer: Measles - five to seven days
Correct Answer: Mumps - 14-18 days
Explanation:The correct match for the disease with its corresponding incubation period is as follows:
– Mumps: 14-18 daysExplanation:
– Chicken pox: The correct incubation period for chickenpox is 5-7 days, not 7-21 days.
– Hand foot and mouth disease: The correct incubation period for hand foot and mouth disease is 2-6 days, not 7-10 days.
– Measles: The correct incubation period for measles is 5-7 days, not 14-21 days.
– Rubella: The correct incubation period for rubella is 7-10 days, not 14-21 days.
– Mumps: The correct incubation period for mumps is 14-18 days, which matches the given information.Understanding the correct incubation periods for different diseases is crucial for proper diagnosis, treatment, and prevention strategies.
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This question is part of the following fields:
- Pathology
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