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Question 1
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A 63-year-old woman is admitted to the medical ward with a 4-week history of fevers and lethargy. During the examination, you observe a few splinter haemorrhages in the fingernails and a loud systolic murmur at the apex. Your consultant advises you to obtain 3 sets of blood cultures and to schedule an echocardiogram. Microbiology contacts you later that day with the preliminary blood culture findings.
What organism is the most probable cause of the growth?Your Answer: Gram positive cocci
Explanation:Gram positive cocci are responsible for the majority of bacterial endocarditis cases. The most common culprits include Streptococcus viridans, Staphylococcus aureus (in individuals who use intravenous drugs or have prosthetic valves), and Staphylococcus epidermidis (in those with prosthetic valves). Other less common causes include Enterococcus, Streptococcus bovis, Candida, HACEK group, and Coxiella burnetii. Acute endocarditis is typically caused by Staphylococcus, while subacute cases are usually caused by Streptococcus species. Knowing the common underlying organisms is crucial for determining appropriate empirical antibiotic therapy. For native valve endocarditis, amoxicillin and gentamicin are recommended. Vancomycin and gentamicin are recommended for NVE with severe sepsis, penicillin allergy, or suspected methicillin-resistant Staphylococcus aureus (MRSA). Vancomycin and meropenem are recommended for NVE with severe sepsis and risk factors for gram-negative infection. For prosthetic valve endocarditis, vancomycin, gentamicin, and rifampicin are recommended. Once blood culture results are available, antibiotic therapy can be adjusted to provide specific coverage. Treatment typically involves long courses (4-6 weeks) of intravenous antibiotic therapy.
Aetiology of Infective Endocarditis
Infective endocarditis is a condition that affects patients with previously normal valves, rheumatic valve disease, prosthetic valves, congenital heart defects, intravenous drug users, and those who have recently undergone piercings. The strongest risk factor for developing infective endocarditis is a previous episode of the condition. The mitral valve is the most commonly affected valve.
The most common cause of infective endocarditis is Staphylococcus aureus, particularly in acute presentations and intravenous drug users. Historically, Streptococcus viridans was the most common cause, but this is no longer the case except in developing countries. Streptococcus mitis and Streptococcus sanguinis are the two most notable viridans streptococci, commonly found in the mouth and dental plaque. Coagulase-negative Staphylococci such as Staphylococcus epidermidis are the most common cause of endocarditis in patients following prosthetic valve surgery.
Streptococcus bovis is associated with colorectal cancer, with the subtype Streptococcus gallolyticus being most linked to the condition. Non-infective causes of endocarditis include systemic lupus erythematosus and malignancy. Culture negative causes may be due to prior antibiotic therapy or infections caused by Coxiella burnetii, Bartonella, Brucella, or HACEK organisms (Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, Kingella).
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This question is part of the following fields:
- Infectious Diseases
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Question 2
Correct
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A 32-year-old man has recently returned from a backpacking trip in Southeast Asia. While there, he consumed food from various street vendors. He complained of abdominal discomfort, bloating and loose stools. Analysis of three stool samples showed cysts in two of them. The patient was treated with metronidazole and showed improvement.
What is the probable medical condition in this scenario?Your Answer: Giardiasis
Explanation:Giardiasis: A Protozoal Parasite Causing Diarrhoeal Illness
Giardiasis is a diarrhoeal disease caused by the flagellate protozoan Giardia intestinalis (previously known as G. lamblia). It is prevalent in areas with poor sanitation and can cause asymptomatic colonisation or acute or chronic diarrhoeal illness. Travellers to highly endemic areas are at high risk of infection. Ingestion of as few as ten Giardia cysts can cause infection. Diarrhoea is the most common symptom of acute Giardia infection, occurring in 90% of symptomatic subjects. The traditional basis of diagnosis is identification of G. intestinalis trophozoites or cysts in the stool of infected patients via stool ova and parasite examination. Standard treatment consists of antibiotic therapy, and metronidazole is the most commonly prescribed antibiotic for this condition. Giardia infection may occur more commonly in families with X-linked agammaglobulinaemia and in sexually active men who have sex with men (MSM).
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This question is part of the following fields:
- Infectious Diseases
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Question 3
Correct
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A 50-year-old man with a persistent chest infection visits the clinic for evaluation. Despite two rounds of antibiotics, there has been no significant improvement. The medical team decides to conduct a chest x-ray and screening blood tests. When analyzing the blood tests, which of the following markers is typically not elevated in response to an acute infection?
Your Answer: Albumin
Explanation:A decrease in albumin levels is frequently observed after an acute phase response.
Acute phase proteins are a group of proteins that are produced by the liver in response to inflammation or infection. These proteins are involved in various physiological processes such as immune response, blood clotting, and iron metabolism. Examples of acute phase proteins include CRP, procalcitonin, ferritin, fibrinogen, alpha-1 antitrypsin, caeruloplasmin, serum amyloid A, serum amyloid P component, haptoglobin, and complement.
During the acute phase response, the liver decreases the production of other proteins known as negative acute phase proteins. These proteins include albumin, transthyretin, transferrin, retinol binding protein, and cortisol binding protein. The levels of acute phase proteins, particularly CRP, are commonly measured in acutely unwell patients. Elevated levels of CRP are indicative of inflammation or infection, and levels greater than 150 at 48 hours post-surgery suggest the development of complications.
It is important to note that while acute phase proteins play a significant role in humans, some of these proteins, such as serum amyloid P component, have a more significant role in other mammals like mice. Overall, the production of acute phase proteins is a crucial part of the body’s response to inflammation or infection, and monitoring their levels can aid in the diagnosis and management of various medical conditions.
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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 35-year-old woman presents to the emergency department with a cat bite on her hand while house-sitting for her neighbor. She complains of mild pain and swelling around the bite but denies having a fever. Upon examination, there is a small puncture wound on the palm of her left hand with mild erythema around it, but no visible purulent discharge. What is the best course of treatment for this patient?
Your Answer: Co-amoxiclav
Explanation:When a patient suffers an animal bite, it is likely that the wound will be infected with multiple types of bacteria. The most frequently identified bacteria in cultures from animal bites is Pasteurella multocida. To prevent infection, it is important to clean the wound thoroughly and provide the patient with tetanus and antibiotics. According to NICE guidelines, co-amoxiclav is the preferred antibiotic as it effectively targets the bacteria commonly found in animal bites.
Animal and Human Bites: Causes and Management
Animal and human bites are common injuries that can lead to infections caused by various microorganisms. Dogs and cats are the most common animals involved in bites, with Pasteurella multocida being the most commonly isolated organism. On the other hand, human bites can cause infections from both aerobic and anaerobic bacteria, including Streptococci spp., Staphylococcus aureus, Eikenella, Fusobacterium, and Prevotella.
To manage animal and human bites, it is important to cleanse the wound thoroughly. Puncture wounds should not be sutured closed unless there is a risk of cosmesis. The current recommendation for treatment is co-amoxiclav, but if the patient is allergic to penicillin, doxycycline and metronidazole are recommended. It is also important to consider the risk of viral infections such as HIV and hepatitis C in human bites.
In summary, animal and human bites can lead to infections caused by various microorganisms. Proper wound cleansing and appropriate antibiotic treatment are essential in managing these injuries. Additionally, healthcare providers should consider the risk of viral infections in human bites.
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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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As a foundation doctor in the emergency decisions unit, you assess a 28-year-old intravenous drug user who complains of pyrexia and malaise. Upon examination, the patient appears cachectic, pale, and is coughing. A soft murmur is detected, and mild erythematous macular lesions are observed on both palms. Although the patient is experiencing general aches, there is no specific tenderness reported. Can you identify the probable diagnosis and explain the significance of the lesions?
Your Answer: Janeway lesions
Explanation:Janeway lesions are painless, red, and bloody lesions that appear on the palms and soles. They are typically associated with infective endocarditis.
Based on the patient’s history of intravenous drug use, fever, and heart murmur, it is likely that he has infective endocarditis. Both janeway lesions (caused by septic emboli) and osler nodes (caused by immune complex deposition) can be present in endocarditis. However, in this case, the lesions are more likely to be janeway lesions as they are not painful.
Roth spots are retinal hemorrhages that can also be seen in endocarditis, but they would be detected during a fundoscopy exam.
If the patient had meningitis, the rash would not be limited to the palms and would not disappear when pressed.
Aetiology of Infective Endocarditis
Infective endocarditis is a condition that affects patients with previously normal valves, rheumatic valve disease, prosthetic valves, congenital heart defects, intravenous drug users, and those who have recently undergone piercings. The strongest risk factor for developing infective endocarditis is a previous episode of the condition. The mitral valve is the most commonly affected valve.
The most common cause of infective endocarditis is Staphylococcus aureus, particularly in acute presentations and intravenous drug users. Historically, Streptococcus viridans was the most common cause, but this is no longer the case except in developing countries. Streptococcus mitis and Streptococcus sanguinis are the two most notable viridans streptococci, commonly found in the mouth and dental plaque. Coagulase-negative Staphylococci such as Staphylococcus epidermidis are the most common cause of endocarditis in patients following prosthetic valve surgery.
Streptococcus bovis is associated with colorectal cancer, with the subtype Streptococcus gallolyticus being most linked to the condition. Non-infective causes of endocarditis include systemic lupus erythematosus and malignancy. Culture negative causes may be due to prior antibiotic therapy or infections caused by Coxiella burnetii, Bartonella, Brucella, or HACEK organisms (Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, Kingella).
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This question is part of the following fields:
- Infectious Diseases
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Question 6
Incorrect
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An epidemic of diarrhoea and vomiting has broken out on one of the elderly care wards. The catering suppliers assure you that their food is unlikely to be responsible because they follow the strictest hygiene procedures. A total of 15 elderly patients on the ward have become unwell with a sudden onset of diarrhoea and vomiting. Those infected earlier have recovered with rehydration therapy after about 48 hours. Examination of faeces by electron microscopy has revealed circular virus particles with radiating spokes.
Which virus is most likely to be responsible for this outbreak?Your Answer: Norovirus
Correct Answer: Rotavirus
Explanation:Common Viruses that Cause Gastroenteritis
Gastroenteritis is a self-limiting illness caused by several viruses, including rotavirus, enteric adenovirus, small round-structured virus (SRSV), norovirus, and astrovirus. Among these, rotavirus is the most common cause of gastroenteritis in children under 5 years of age, while norovirus affects people of all ages. Rotavirus causes infant deaths worldwide, but acquired immunity develops after one episode. Norovirus is usually transmitted through contaminated food or water, while adenovirus is endemic throughout the year and commonly affects children in daycare settings. SRSV is another name for norovirus, and astrovirus is associated with contaminated food and water. Symptoms of gastroenteritis include anorexia, low-grade fever, vomiting, and watery diarrhea, but most cases do not require medication and can be managed with supportive treatment. Death from dehydration remains common in developing countries.
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This question is part of the following fields:
- Infectious Diseases
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Question 7
Correct
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After hepatitis B immunisation, which serological marker indicates successful immunisation? Choose ONE option from the list provided.
Your Answer: Anti-HBs antibodies
Explanation:Understanding Hepatitis B Antibodies and Antigens
Hepatitis B is a viral infection that affects the liver. To diagnose and manage the disease, healthcare providers rely on various serologic tests that detect specific antibodies and antigens in the blood. Here are some key markers and their significance:
Anti-HBs antibodies: These antibodies are produced after a resolved infection or vaccination. They indicate immunity to hepatitis B.
HBs antigen: This antigen is present in the blood during an acute infection. Its detection confirms the diagnosis of hepatitis B.
Anti-HBe antibodies: These antibodies appear during recovery from acute hepatitis B or in inactive carriers. They suggest a lower risk of infectivity.
Anti-HBc antibodies: These antibodies are present in both acute and chronic hepatitis B. Their detection helps distinguish between recent and past infections.
HBe antigen: This antigen is a marker of high infectivity and viral replication. Its presence indicates a higher risk of transmission.
Understanding these markers can help healthcare providers diagnose and manage hepatitis B infections more effectively. It can also help individuals understand their immune status and make informed decisions about vaccination and prevention.
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This question is part of the following fields:
- Infectious Diseases
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Question 8
Correct
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A 26-year-old male patient complains of painful ulcers on his penis shaft and dysuria for the past three days. He has never experienced such symptoms before. The clinical diagnosis suggests primary genital herpes. What is the best course of action for managing this condition?
Your Answer: Oral aciclovir
Explanation:Even if the presentation is delayed for up to 5 days, primary genital herpes infections require oral antiviral therapy.
Understanding Herpes Simplex Virus
Herpes simplex virus (HSV) is a common viral infection that affects humans. There are two strains of the virus, HSV-1 and HSV-2, which were previously thought to cause oral and genital herpes, respectively. However, there is now considerable overlap between the two strains. The primary infection may present with severe gingivostomatitis, while cold sores and painful genital ulceration are common features.
Management of HSV includes oral aciclovir for gingivostomatitis and genital herpes, and topical aciclovir for cold sores, although the evidence base for the latter is modest. Patients with frequent exacerbations may benefit from longer-term aciclovir. In pregnant women, a primary attack of herpes during pregnancy at greater than 28 weeks gestation may require elective caesarean section at term. Women with recurrent herpes who are pregnant should be treated with suppressive therapy and advised that the risk of transmission to their baby is low.
The cytopathic effect of HSV can be seen in Pap smears, which show multinucleated giant cells representing infection by the virus. The 3 M’s – multinucleation, margination of the chromatin, and molding of the nuclei – are characteristic features of HSV infection. Understanding the features and management of HSV is important for effective treatment and prevention of transmission.
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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 68-year-old man is admitted to the gastroenterology ward with a 9-day history of cramping abdominal pain, fever and diarrhoea, opening his bowels up to 7 times per day. He has a past medical history of COPD and reports to have completed 2 courses of antibiotics to treat an exacerbation within the last 2 weeks.
After being diagnosed with a likely infection, the patient is started on oral vancomycin but shows little improvement. The treatment is then switched to fidaxomicin, but he still reports ongoing pain and diarrhoea even after completing the course.
What would be the most appropriate next step in managing this patient's condition?Your Answer: Oral vancomycin and intravenous metronidazole
Explanation:If the initial treatment of C. difficile with vancomycin or fidaxomicin is ineffective, the next step should be to administer oral vancomycin with or without intravenous metronidazole.
Clostridioides difficile is a type of bacteria that is commonly found in hospitals. It is a Gram positive rod that produces an exotoxin which can cause damage to the intestines, leading to a condition called pseudomembranous colitis. This bacteria usually develops when the normal gut flora is suppressed by broad-spectrum antibiotics, with second and third generation cephalosporins being the leading cause of C. difficile. Other risk factors include proton pump inhibitors. Symptoms of C. difficile include diarrhea, abdominal pain, and a raised white blood cell count. The severity of the infection can be determined using the Public Health England severity scale, which ranges from mild to life-threatening.
To diagnose C. difficile, a stool sample is tested for the presence of C. difficile toxin (CDT). Treatment for a first episode of C. difficile infection typically involves oral vancomycin for 10 days, with fidaxomicin or a combination of oral vancomycin and IV metronidazole being used as second and third-line therapies. Recurrent infections occur in around 20% of patients, increasing to 50% after their second episode. In such cases, oral fidaxomicin is recommended within 12 weeks of symptom resolution, while oral vancomycin or fidaxomicin can be used after 12 weeks. For life-threatening C. difficile infections, oral vancomycin and IV metronidazole are used, and surgery may be considered with specialist advice. Other therapies, such as bezlotoxumab and fecal microbiota transplant, may also be considered for preventing recurrences in certain cases.
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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 65-year-old patient with chronic obstructive pulmonary disease (COPD) who continues to smoke is housebound due to his disability.
Which of the following immunisations should he receive on a yearly basis?Your Answer: Influenza A virus
Explanation:Common Vaccinations and Their Administration Schedule
Influenza, caused by three types of viruses, is a highly contagious respiratory tract infection. The influenza vaccination programme aims to protect those at risk of severe disease or complications. The World Health Organisation recommends the strains of influenza to include in the vaccine each year. Inactivated vaccines are available in the UK, containing two subtypes of influenza A and one of influenza B virus. The vaccine is recommended for children aged 6 months to 2 years in an at-risk group, those aged 18 years and over in an at-risk group, pregnant women, those aged 65 years and older, those in long-stay residential care homes, and carers.
Haemophilus influenzae type b (Hib) is a bacterium that can cause serious infections, including meningitis. Vaccination against Hib is administered in children as part of the 6-in-1 vaccine at 8, 12, and 16 weeks of age.
Clostridium tetani is a bacterium that causes tetanus, a serious disease that affects the nervous system. Vaccination against tetanus is administered in children as part of the 6-in-1 vaccine at 8, 12, and 16 weeks of age.
Hepatitis B is a virus that can cause liver disease. Vaccination against hepatitis B is administered in children as part of the 6-in-1 vaccine at 8, 12, and 16 weeks of age.
Streptococcus pneumoniae is a bacterium that can cause pneumonia, meningitis, and other serious infections. Pneumococcal vaccine is administered to children at 8, 16, and 18 weeks and to those at high risk due to long-term health conditions at 65 years of age or older (pneumococcal polysaccharide vaccine – PPV).
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This question is part of the following fields:
- Infectious Diseases
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Question 11
Correct
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A teenager returns from a backpacking holiday in South America, having developed abdominal pain, diarrhoea and fevers one week before his return. On examination, he has a fever of 38.5 °C and diffuse abdominal pain. Stool microscopy shows pus and red blood cells; culture is awaited.
Which of the following is the most likely organism?Your Answer: Salmonella species
Explanation:Common Causes of Gastroenteritis in Travellers
Travellers are at risk of contracting various infections that can cause gastroenteritis. Salmonella species, transmitted through contaminated food or beverages, can cause non-typhoidal enterocolitis, non-typhoidal focal disease, or typhoid fever. Rotavirus, which causes self-limited gastroenteritis, typically presents with anorexia, low-grade fever, and watery, bloodless diarrhea. Plasmodium falciparum, a parasite that causes malaria, can be detected through blood films. Norovirus, the most common cause of epidemic non-bacterial gastroenteritis, presents with nausea, vomiting, watery non-bloody/non-purulent diarrhea, and low-grade fever. Vibrio cholerae, which causes cholera, is transmitted through contaminated water or food and can cause severe watery diarrhea, vomiting, and dehydration. It is important to consider these potential causes when diagnosing gastroenteritis in returning travellers.
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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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Which one of the following statements regarding listeria infection in elderly individuals is accurate?
Your Answer: Diagnosis is made by taking blood for listeria IgM
Correct Answer: Pregnant women are 20 times more likely to develop listeriosis compared with the rest of the population
Explanation:Listeria: A Dangerous Bacterial Infection
Listeria monocytogenes is a type of bacteria that can cause serious illness in certain populations. This Gram-positive bacillus has the unique ability to multiply at low temperatures, making it a common contaminant in unpasteurized dairy products. The infection is particularly dangerous for pregnant women, as it can lead to miscarriage and other complications. Other at-risk populations include the elderly, neonates, and those with weakened immune systems.
Listeria infections can present in a variety of ways, including gastroenteritis, diarrhea, bacteraemia, and flu-like illness. In severe cases, it can lead to central nervous system infections such as meningoencephalitis, ataxia, and seizures. Diagnosis is typically made through blood cultures or cerebrospinal fluid findings.
Treatment for Listeria infections typically involves antibiotics such as amoxicillin or ampicillin. In cases of Listeria meningitis, gentamicin may also be used. Pregnant women are at a particularly high risk for Listeria infection, and diagnosis can only be made through blood cultures. Treatment with amoxicillin is recommended to prevent complications such as miscarriage, premature labor, stillbirth, and chorioamnionitis.
Overall, Listeria is a dangerous bacterial infection that requires prompt diagnosis and treatment, particularly in at-risk populations.
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This question is part of the following fields:
- Infectious Diseases
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Question 13
Incorrect
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What is the most suitable antibiotic for treating uncomplicated Chlamydia infection in a 22-year-old female who is not expecting?
Your Answer: Azithromycin
Correct Answer: Doxycycline
Explanation:Doxycycline is the recommended treatment for chlamydia.
Chlamydia is a common sexually transmitted infection caused by Chlamydia trachomatis. It is prevalent in the UK, with approximately 1 in 10 young women affected. The incubation period is around 7-21 days, but many cases are asymptomatic. Symptoms in women include cervicitis, discharge, and bleeding, while men may experience urethral discharge and dysuria. Complications can include epididymitis, pelvic inflammatory disease, and infertility.
Traditional cell culture is no longer widely used for diagnosis, with nuclear acid amplification tests (NAATs) being the preferred method. Testing can be done using urine, vulvovaginal swab, or cervical swab. Screening is recommended for sexually active individuals aged 15-24 years, and opportunistic testing is common.
Doxycycline is the first-line treatment for Chlamydia, with azithromycin as an alternative if doxycycline is contraindicated or not tolerated. Pregnant women may be treated with azithromycin, erythromycin, or amoxicillin. Patients diagnosed with Chlamydia should be offered partner notification services, with all contacts since the onset of symptoms or within the last six months being notified and offered treatment.
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This question is part of the following fields:
- Infectious Diseases
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Question 14
Correct
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A 42-year-old male complains of difficulty breathing after experiencing flu-like symptoms for a week. He has a dry cough and no chest discomfort. A chest x-ray reveals bilateral consolidation, and he has red rashes on his limbs and torso. Which test is most likely to provide a definitive diagnosis?
Your Answer: Serology for Mycoplasma
Explanation:A diagnosis of Mycoplasma can be made based on symptoms such as flu-like symptoms, bilateral consolidation, and erythema multiforme. The most suitable diagnostic test for this condition is Mycoplasma serology.
Mycoplasma pneumoniae: A Cause of Atypical Pneumonia
Mycoplasma pneumoniae is a type of bacteria that causes atypical pneumonia, which is more common in younger patients. This disease is associated with various complications such as erythema multiforme and cold autoimmune haemolytic anaemia. Epidemics of Mycoplasma pneumoniae typically occur every four years. It is important to recognize atypical pneumonia because it may not respond to penicillins or cephalosporins due to the bacteria lacking a peptidoglycan cell wall.
The disease usually has a gradual onset and is preceded by flu-like symptoms, followed by a dry cough. X-rays may show bilateral consolidation. Complications may include cold agglutinins, erythema multiforme, erythema nodosum, meningoencephalitis, Guillain-Barre syndrome, bullous myringitis, pericarditis/myocarditis, and gastrointestinal and renal problems.
Diagnosis is generally made through Mycoplasma serology and a positive cold agglutination test. Management involves the use of doxycycline or a macrolide such as erythromycin or clarithromycin.
In comparison to Legionella pneumonia, which is caused by a different type of bacteria, Mycoplasma pneumoniae has a more gradual onset and is associated with different complications. It is important to differentiate between the two types of pneumonia to ensure appropriate treatment.
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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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A 35-year-old man presents with a swollen, erythematous finger and right axillary tenderness, 24 hours after being bitten by his pet dog.
Which of the following is the best treatment?Your Answer: Co-amoxiclav
Explanation:Antibiotics for Dog Bite Infections: Recommended and Not Recommended Options
Dog bites can lead to infections caused by various micro-organisms, including anaerobic mouth flora and bacteria. Co-amoxiclav, a combination of amoxicillin and clavulanic acid, is the recommended antibiotic for dog bite-related infections, as it is effective against the most likely organisms. Fluconazole, an antifungal agent, is not indicated for such infections, as fungal micro-organisms in dogs usually cause only superficial skin rashes. Metronidazole, although effective against anaerobic bacteria, is not recommended for dog bite-related infections, except for patients allergic to penicillin. Aciclovir is not used for dog bite-related infections, as it is restricted to treating varicella-zoster and herpes zoster. Flucloxacillin, although recommended for skin infections, is not active against anaerobic bacteria and is not recommended for dog bite-related infections.
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This question is part of the following fields:
- Infectious Diseases
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Question 16
Incorrect
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A 38-year-old teacher presents with ongoing fatigue. During a routine blood test, abnormal liver function tests are detected, prompting a hepatitis screen. The results are as follows:
Negative for Anti-HAV IgG
Negative for HBsAg
Positive for Anti-HBs
Negative for Anti-HBc
Positive for Anti-HCV
What is the most likely interpretation of these results?Your Answer: Hepatitis B and C infection
Correct Answer: Hepatitis C infection with previous hepatitis B vaccination
Explanation:To determine if a patient still has the hepatitis C virus, a HCV PCR test is necessary as only a small percentage of patients naturally clear the infection. Unfortunately, there is currently no vaccine available for hepatitis C.
When interpreting hepatitis B serology, the presence of surface antigen (HBsAg) typically indicates acute disease and triggers the production of anti-HBs. If HBsAg is present for more than six months, it suggests chronic disease and is infectious. Anti-HBs indicates immunity from either exposure or vaccination, while anti-HBc suggests previous or current infection. The appearance of IgM anti-HBc during acute or recent hepatitis B infection lasts for about six months. HbeAg is a marker of infectivity as it results from the breakdown of core antigen from infected liver cells.
Understanding Hepatitis C: Transmission, Complications, and Management
Hepatitis C is a viral infection that is expected to become a significant public health concern in the UK in the coming years. It is estimated that around 200,000 people in the country are chronically infected with the virus, with intravenous drug users and those who received blood transfusions prior to 1991 being at higher risk. The virus is an RNA flavivirus with an incubation period of 6-9 weeks.
Transmission of the virus can occur through needle stick injuries, vertical transmission from mother to child (especially if coexistent with HIV), and sexual intercourse (although the risk is low). There is currently no vaccine for hepatitis C. Symptoms of acute infection include a transient rise in serum aminotransferases, jaundice, fatigue, and arthralgia.
Around 15-45% of patients will clear the virus after an acute infection, while the majority (55-85%) will develop chronic hepatitis C. This can lead to complications such as rheumatological problems, cirrhosis, hepatocellular cancer, and cryoglobulinemia. Treatment for chronic infection depends on the viral genotype and aims for sustained virological response (SVR), defined as undetectable serum HCV RNA six months after the end of therapy. Interferon-based treatments are no longer recommended, with protease inhibitors such as daclatasvir and sofosbuvir or sofosbuvir and simeprevir being used instead. However, these treatments can have side effects such as haemolytic anaemia, cough, flu-like symptoms, depression, and fatigue.
In conclusion, understanding the transmission, complications, and management of hepatitis C is crucial in addressing this growing public health concern.
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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 32-year-old man comes to the clinic with a maculopapular rash and mouth ulcers. He had a painless penile ulcer two months ago. What is the most probable causative organism for his symptoms?
Your Answer: Treponema pallidum
Explanation:The symptoms exhibited by this individual suggest the presence of secondary syphilis.
Understanding Syphilis: Symptoms and Stages
Syphilis is a sexually transmitted infection caused by the bacterium Treponema pallidum. The infection progresses through three stages: primary, secondary, and tertiary. The incubation period can range from 9 to 90 days.
During the primary stage, a painless ulcer called a chancre appears at the site of sexual contact. Local lymph nodes may also become swollen, but this symptom may not be visible in women if the lesion is on the cervix.
The secondary stage occurs 6 to 10 weeks after the primary infection and is characterized by systemic symptoms such as fevers and lymphadenopathy. A rash may appear on the trunk, palms, and soles, along with buccal ulcers and painless warty lesions on the genitalia.
In the tertiary stage, granulomatous lesions called gummas may develop on the skin and bones, and there may be an ascending aortic aneurysm. Other symptoms include general paralysis of the insane, tabes dorsalis, and Argyll-Robertson pupil.
Congenital syphilis can also occur if a pregnant woman is infected. Symptoms include blunted upper incisor teeth, linear scars at the angle of the mouth, keratitis, saber shins, saddle nose, and deafness.
Understanding the symptoms and stages of syphilis is important for early detection and treatment. It is a treatable infection, but if left untreated, it can lead to serious complications.
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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 6-year-old girl is brought to her general practitioner by her mother, with a 3-day history of fever up to 37.8 °C. She had no history of lesions on the buccal mucosa but developed a maculopapular rash across the face and trunk. A few days before the appearance of the rash, she complained of some eye pain, sore throat and general body aches. On physical examination, she has a discrete rose-pink maculopapular rash on the face, neck and trunk, low-grade fever and enlarged posterior auricular and suboccipital lymph nodes.
What is the most likely diagnosis?Your Answer: Rubella
Explanation:Distinguishing Between Viral Diseases: Rubella, Mumps, Meningitis, Scarlet Fever, and Erythema Infectiosum
Rubella, also known as German measles, is a typically mild viral disease that often goes unnoticed, with almost half of those infected showing no symptoms. However, it can have severe consequences for pregnant women, especially in the early stages of pregnancy. Symptoms include eye pain, sore throat, low-grade fever, and a rose-pink rash that starts on the face and spreads to the trunk and extremities within 24 hours.
Mumps is another viral disease caused by rubulavirus. It typically presents with low-grade fever, malaise, headache, and myalgia, followed by painful swelling of the salivary glands and tender cervical lymphadenopathy. Mumps is highly contagious and has become less common in developing countries due to vaccination.
Meningitis is a serious condition characterized by inflammation of the meninges. Symptoms include fever, headache, and neck stiffness, and it requires urgent medical attention.
Scarlet fever is caused by group A β-hemolytic streptococci and presents with exudative pharyngitis, fever, and a bright red rash. It typically evolves from a tonsillar/pharyngeal focus and is uncommon without buccal lesions.
Erythema infectiosum, also known as fifth disease, is a mild childhood illness caused by parvovirus B19. It presents with a bright red rash on the cheeks and may have atypical rashes in adults.
It is important to distinguish between these viral diseases to ensure proper treatment and prevent complications.
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This question is part of the following fields:
- Infectious Diseases
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Question 19
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A 28-year-old woman presents to the Emergency Department with a one week history of cough and increasing shortness of breath over the past 48 hours. She also reports fever, headache, anorexia, and chills. Upon examination, she appears slightly pale and confused. Her vital signs reveal a pulse of 136/min, blood pressure of 96/64 mmHg, respiratory rate of 32/min, and oxygen saturation of 89% on room air. Lung auscultation reveals reduced breath sounds in the left lower lung with some coarse crackles. Blood cultures are taken and the patient is cannulated. High flow oxygen is administered and a fluid challenge is ordered by the nurse. What is the most appropriate next step?
Your Answer: Prescribe broad spectrum intravenous antibiotics
Explanation:If the patient’s condition worsens, ITU may be consulted. However, before referring the patient, it is important to determine if she has already received basic sepsis care. Although studies have explored the use of steroids in sepsis, they are not presently recommended due to an increase in mortality.
Understanding Sepsis: Classification and Management
Sepsis is a life-threatening condition caused by a dysregulated host response to an infection. In recent years, the classification of sepsis has changed, with the old category of severe sepsis no longer in use. Instead, the Surviving Sepsis Guidelines now recognize sepsis as life-threatening organ dysfunction caused by a dysregulated host response to infection, and septic shock as a more severe form of sepsis. The term ‘systemic inflammatory response syndrome (SIRS)’ has also fallen out of favor.
To manage sepsis, it is important to identify and treat the underlying cause of the infection and support the patient regardless of the cause or severity. However, if any red flags are present, the ‘sepsis six’ should be started immediately. This includes administering oxygen, taking blood cultures, giving broad-spectrum antibiotics, giving intravenous fluid challenges, measuring serum lactate, and measuring accurate hourly urine output.
NICE released its own guidelines in 2016, which focus on the risk stratification and management of patients with suspected sepsis. For risk stratification, NICE recommends using red flag and amber flag criteria. If any red flags are present, the sepsis six should be started immediately. If any amber flags are present, the patient should be closely monitored and managed accordingly.
To help identify and categorize patients, the Sequential (Sepsis-Related) Organ Failure Assessment Score (SOFA) is increasingly used. The score grades abnormality by organ system and accounts for clinical interventions. A SOFA score of 2 or more reflects an overall mortality risk of approximately 10% in a general hospital population with suspected infection. Even patients presenting with modest dysfunction can deteriorate further, emphasizing the seriousness of this condition and the need for prompt and appropriate intervention.
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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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A 50-year-old businessman comes to the clinic complaining of watery, non-bloody diarrhea, anorexia, and abdominal bloating that has been going on for 10 days. He recently returned from a trip to India and his symptoms started 3 days after his return. Upon examination, he has dry mucous membranes but normal skin turgor and no fever. What is the probable organism responsible for his symptoms?
Your Answer:
Correct Answer: Giardia lamblia
Explanation:The symptoms experienced by the patient, such as bloating and watery diarrhoea lasting for an extended period, suggest that the cause of their illness is Giardiasis rather than the more typical culprit, Escherichia coli, which is commonly associated with travellers’ diarrhoea.
Understanding Giardiasis
Giardiasis is a condition caused by a type of protozoan called Giardia lamblia. It is transmitted through the faeco-oral route and can be contracted through various means such as foreign travel, drinking water from rivers or lakes, and even male-male sexual contact. While some individuals may not experience any symptoms, others may suffer from non-bloody diarrhea, bloating, abdominal pain, lethargy, flatulence, and weight loss. In severe cases, malabsorption and lactose intolerance may occur. Diagnosis can be made through stool microscopy, stool antigen detection assay, or PCR assays. Treatment typically involves the use of metronidazole.
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This question is part of the following fields:
- Infectious Diseases
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