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  • Question 1 - A 52-year-old woman presented with abdominal pain, fever and weight loss. Abdominal imaging...

    Incorrect

    • A 52-year-old woman presented with abdominal pain, fever and weight loss. Abdominal imaging revealed multiple retroperitoneal lymph nodes. She was diagnosed with intestinal tuberculosis and received a full drug regimen for six months. However, after completion of treatment, her symptoms remain. She presents to us with a body weight of 38 kg. There is angular stomatitis and diffuse loss of hair. She looks tanned. Repeat abdominal imaging reveals persistence of the lymph nodes. Her son, who accompanied her, complains that his mother is becoming listless and she has even given up her favourite hobby of Sudoku. She also has a few involuntary movements of her face, such as chewing.
      Which of the following is the most likely diagnosis?

      Your Answer: Huntington’s chorea

      Correct Answer: Whipple’s disease

      Explanation:

      Whipple’s Disease: A Multisystem Disorder with Malabsorption and Cognitive Decline

      This patient presents with iron deficiency, abdominal lymphadenopathy, hyperpigmentation, and cognitive decline. Despite treatment for tuberculosis, there has been no improvement. These symptoms suggest a possible diagnosis of Whipple’s disease, a multisystem disorder caused by infection with Tropheryma whipplei. Malabsorption with abdominal lymphadenopathy is a common manifestation, and extraintestinal symptoms can include cognitive decline with facial involuntary movements, arthritis, hyperpigmentation, retinitis, and endocarditis. HIV dementia, prion disease, Huntington’s chorea, and coeliac disease are all ruled out based on the patient’s clinical presentation and lack of risk factors.

    • This question is part of the following fields:

      • Microbiology
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  • Question 2 - A 26-year-old woman presents with a history of lethargy and increased frequency of...

    Incorrect

    • A 26-year-old woman presents with a history of lethargy and increased frequency of infections. The patient reports that she has had three separate episodes of skin infections in the past six months, and at least two to three colds a month for nearly a year. She feels that recently, she has always been ill with some little thing or another and has felt generally run down.
      She is concerned, as she has had a lot of sick leave from her work in a factory and worries that her employment will be terminated soon if she keeps missing work. She had mild asthma as a child but has no other history of note.
      On further questioning, the patient admits to intravenous (IV) drug use in the past; however, she has not used drugs for nearly two years. She does not drink alcohol and is currently single.
      As a part of initial investigations, bloods are taken for various tests, including human immunodeficiency virus (HIV).
      Which of the following is correct regarding HIV?

      Your Answer:

      Correct Answer: Establishes persistence through antigenic variation

      Explanation:

      Understanding HIV: How the Virus Establishes Persistence and Evades the Immune System

      HIV is a retrovirus that primarily targets and destroys CD4 T-cells, leading to a decline in immune function. The virus can also infect macrophages and dendritic cells, establishing a reservoir of infection in lymphoid tissues. One of the ways HIV evades the immune system is through antigenic variation, constantly mutating and overwhelming the immune system with a huge number of antigenic variants. HIV is transmitted through sexual contact, blood-borne transmission, or vertically from mother to baby. It is an RNA virus that contains three viral enzymes, including reverse transcriptase, protease, and integrase. Understanding how HIV establishes persistence and evades the immune system is crucial in developing effective treatments and prevention strategies.

    • This question is part of the following fields:

      • Microbiology
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  • Question 3 - A 32-year-old woman visits her GP complaining of dysuria and urinary frequency that...

    Incorrect

    • A 32-year-old woman visits her GP complaining of dysuria and urinary frequency that have been present for 2 weeks. She denies any recent sexual activity or vaginal discharge and is in good health otherwise. The GP suspects a UTI. What is the leading cause of UTIs?

      Your Answer:

      Correct Answer: Escherichia coli

      Explanation:

      Common Bacteria that Cause Urinary Tract Infections

      Urinary tract infections (UTIs) are a common health problem caused by bacterial infections. The following are some of the most common bacteria that cause UTIs:

      Escherichia coli (E. coli): This bacterium is responsible for up to 90% of UTIs. E. coli is part of the normal flora of the colon, and perianal colonisation can lead to ascending infection of the urethra. UTIs may involve the urethra (urethritis) or may ascend to infect the bladder (cystitis) or kidneys (pyelonephritis).

      Staphylococcus aureus (S. aureus): This bacterium causes infections of the skin and wounds but, in severe cases, can also cause pneumonia, osteomyelitis, and endocarditis. They are also found as a commensal skin bacterium.

      Proteus mirabilis: This is a less common cause of UTI but, like E. coli, is an enteric organism.

      Klebsiella: This is also a less common cause of UTI but, like E. coli, is an enteric organism having spread from the anus.

      Candida albicans: Candida is an unlikely cause for a UTI and is a far more common cause of vaginal infections, and can commonly contaminate a urine sample. Only in immunosuppression or if strong clinical suspicion should a urine sample growing Candida be considered to be a fungal UTI.

      To diagnose a UTI, a urine dipstick test is needed to look for the presence of nitrites and leukocytes. If these are present, then empirical treatment is usually started with a 3-day course of trimethoprim (7-day course in men). If symptoms persist, then a mid-stream specimen of urine is sent for analysis where infection is diagnosed by the presence of >105 organisms per ml. The symptoms of UTIs may vary depending on the location of the infection.

    • This question is part of the following fields:

      • Microbiology
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  • Question 4 - A 14-year-old girl presents with a 3-day history of fever and polyarthralgia. She...

    Incorrect

    • A 14-year-old girl presents with a 3-day history of fever and polyarthralgia. She has widespread aches in multiple joints, including the hips, wrists and knees. She is normally fit and well, and the only medical history to note was eczema as a child, which she has now grown out of. The patient’s mother mentions that she did have a sore throat around two weeks ago, which was self-limiting. From the history and examination findings, the examining doctor feels that the patient is likely to have rheumatic fever.
      Which of the following is most likely to be the cause of rheumatic fever?

      Your Answer:

      Correct Answer: Group A Streptococcus

      Explanation:

      Different Types of Streptococcus Bacteria and Their Associated Infections

      Streptococcus bacteria are a group of Gram-positive bacteria that can cause a variety of infections in humans. Here are some of the different types of Streptococcus bacteria and the infections they are associated with:

      1. Group A Streptococcus: This type of bacteria can cause rheumatic fever, tonsillitis, erysipelas, scarlet fever, cellulitis, septic arthritis, Henoch–Schönlein purpura, post-streptococcal autoimmunity, and erythema multiforme.

      2. Group B Streptococcus: This type of bacteria can cause septic abortion and bacterial meningitis.

      3. Gamma-haemolytic Streptococcus: This type of bacteria is classified as gamma-haemolytic because it does not break down red blood cells on blood agar plates.

      4. Streptococcus pneumoniae: This type of bacteria is a common cause of community-acquired pneumonia.

      5. Streptococcus viridans: This type of bacteria is an important cause of bacterial endocarditis.

      Overall, it is important to be aware of the different types of Streptococcus bacteria and the infections they can cause in order to properly diagnose and treat these infections.

    • This question is part of the following fields:

      • Microbiology
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  • Question 5 - A 30-year-old man comes to the Emergency Department with a headache that has...

    Incorrect

    • A 30-year-old man comes to the Emergency Department with a headache that has been bothering him for the past 48 hours. He is experiencing neck stiffness and photophobia, and his temperature is 39 °C. The Brudzinski sign is positive. The patient has a history of intravenous drug use (IVDU) and human immunodeficiency virus (HIV) infection. He admits to not following his highly active antiretroviral therapy (HAART) medication regimen. A lumbar puncture is performed, and the cerebrospinal fluid (CSF) analysis reveals budding yeast cells that stain strongly with India Ink. What antimicrobial medication would you suggest?

      Your Answer:

      Correct Answer: Amphotericin B

      Explanation:

      Antifungal Treatment for Cryptococcal Meningitis

      The patient in question is likely immunosuppressed due to non-compliance with medication, making meningitis a possibility. Microscopy revealed budding yeast cells that stained positive with India Ink, indicating cryptococcal meningitis. Treatment for this organism is antifungal medication, specifically amphotericin B. Clotrimazole is used for candida infections, while azithromycin is effective against intracellular bacteria like chlamydia. Ceftriaxone is given prior to diagnosis, but would not affect the organism present. Co-amoxiclav is not effective against cryptococcal meningitis.

    • This question is part of the following fields:

      • Microbiology
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  • Question 6 - A 16-year-old girl, originally from India, has been exhibiting behavioural problems at school....

    Incorrect

    • A 16-year-old girl, originally from India, has been exhibiting behavioural problems at school. After a few months, she started experiencing involuntary movements of her limbs and is now having tonic-clonic seizures. A diagnosis of subacute sclerosing panencephalitis has been confirmed through an EEG. Which infectious agent is likely to be detected in her cerebrospinal fluid (CSF) antibodies?

      Your Answer:

      Correct Answer: Measles

      Explanation:

      Subacute Sclerosing Panencephalitis: A Rare Complication of Measles

      Subacute sclerosing panencephalitis (SSPE) is a progressive neurological disorder caused by the measles virus and is a rare complication of measles. It typically occurs 5-10 years after the initial measles infection. The diagnosis of SSPE is based on clinical symptoms such as behavioural changes, myoclonus, dementia, and visual disturbances, along with the presence of characteristic periodic EEG discharges called Rademecker complexes, and a raised antibody titre against measles in the plasma and cerebrospinal fluid.

      Treatment for SSPE involves lifelong oral isoprinosine and intraventricular interferon. However, if the patient does not respond, SSPE usually causes death within 1-3 years. The best way to prevent SSPE is through vaccination against measles.

      Other viral infections such as mumps, rubella, varicella zoster, and malaria are not associated with SSPE. Cerebral malaria may present with an unarousable coma, which is unlikely to be seen in SSPE until the very end stage of the disease.

    • This question is part of the following fields:

      • Microbiology
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  • Question 7 - A pediatric hospital adopts a set of infection management practice guidelines developed within...

    Incorrect

    • A pediatric hospital adopts a set of infection management practice guidelines developed within the local community. If the medical staff follows these guidelines, what is the expected outcome?

      Your Answer:

      Correct Answer: Stable antibiotic susceptibility patterns for bacteria

      Explanation:

      The Benefits of Guideline Use in Antibiotic Treatment

      Guideline use in antibiotic treatment has been linked to stable antibiotic susceptibility patterns in both Gram positive and Gram negative bacteria. This is thought to be due to the promotion of antimicrobial heterogeneity. Additionally, guideline use has been associated with a decrease in overall antibiotic use and a reduction in the use of inadequate treatment regimens. These factors could potentially impact the development of antibiotic resistance. The use of automated guidelines has also been shown to decrease adverse drug effects and improve antibiotic selection. Overall, the use of guidelines in antibiotic treatment can have numerous benefits for both patients and the healthcare system.

    • This question is part of the following fields:

      • Microbiology
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  • Question 8 - A 45-year-old woman with human immunodeficiency virus (HIV) is hospitalized due to dehydration...

    Incorrect

    • A 45-year-old woman with human immunodeficiency virus (HIV) is hospitalized due to dehydration caused by chronic diarrhea. What is the most frequently identified pathogen in cases of chronic diarrhea linked to HIV?

      Your Answer:

      Correct Answer: Cryptosporidium

      Explanation:

      Common Causes of Diarrhoea in Immunocompromised Patients

      Immunocompromised patients, particularly those with HIV infection, are at increased risk of developing chronic diarrhoea. Among the causative organisms, Cryptosporidium is the most commonly isolated. This intracellular protozoan parasite can cause severe debilitating diarrhoea with weight loss and malabsorption in HIV-infected patients. Treatment involves fluid rehydration, electrolyte correction, and pain management, with the initiation of highly active antiretroviral therapy (HAART) being crucial for restoring immunity.

      Salmonella, Isospora belli, Campylobacter, and Shigella are other common causes of diarrhoea in immunosuppressed patients. Salmonella infection typically occurs after eating uncooked foods such as chicken, while Isospora species can also cause diarrhoea but not as commonly as Cryptosporidium. Campylobacter infection can present with a flu-like prodrome, fever, and in severe cases, bloody diarrhoea and severe colitis. Treatment often involves quinolones, but one complication to be wary of is the subsequent development of neurological symptoms due to Guillain–Barré syndrome. Shigella infection typically presents with bloody diarrhoea after ingestion of the toxin.

    • This question is part of the following fields:

      • Microbiology
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  • Question 9 - A 62-year-old woman came to the clinic with complaints of abdominal bloating and...

    Incorrect

    • A 62-year-old woman came to the clinic with complaints of abdominal bloating and diarrhea for the past week. She was especially bothered by frequent passing of gas. She had recently returned from a trip to India where she was involved in missionary work. There was no presence of blood in her stool. Additionally, she reported experiencing mild nausea. She had no history of abdominal surgery and was not taking any medications. What is the recommended course of treatment?

      Your Answer:

      Correct Answer: Metronidazole, 400 mg three times daily (tid) for 5 days

      Explanation:

      If a person has not followed proper food hygiene while traveling in the Indian subcontinent, they may develop infectious diseases. Symptoms such as bloating, belching, and flatulence suggest acute Giardia infection, which can lead to chronic infection and malabsorption if left untreated. The recommended treatment is metronidazole 400 mg three times daily for five days. Tinidazole 2 g single-dose therapy is also effective, but three days of treatment are excessive. Albendazole 400 mg is used to treat intestinal helminth infections. Oral rehydration therapy is suitable for viral or toxin-mediated diarrhea, but it is not the first choice. If left untreated, chronic infection may persist, so any suspected episode of giardiasis should be treated.

    • This question is part of the following fields:

      • Microbiology
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  • Question 10 - A 35-year-old man visits his General Practitioner to receive the results of an...

    Incorrect

    • A 35-year-old man visits his General Practitioner to receive the results of an HIV test, which come back positive. What test would be the most helpful in determining his likelihood of developing an opportunistic infection (OI)?

      Your Answer:

      Correct Answer: CD4 count

      Explanation:

      Diagnostic Tests for HIV-Related Immune Impairment

      The CD4 count is a reliable indicator of HIV-related immune impairment. In HIV-negative individuals, the CD4 count is usually maintained above 600-800 cells/µl. Without antiretroviral therapy (ART), HIV-positive individuals will experience a gradual decline in CD4 count. A CD4 count of <350 cells/µl is associated with an increased risk of opportunistic infections (OI), while a count of <200 cells/µl indicates an 80% risk of developing an OI over the next three years. Chest X-rays are usually normal in HIV-positive individuals without a history of chronic respiratory disorders. Blood cultures may be useful in diagnosing the presence of an OI, but will not help estimate the risk of developing OIs. HIV-positive individuals often have an abnormal full blood count (FBC), being at higher risk of anaemia, lymphopenia, and thrombocytopenia. However, these abnormalities may be for a variety of reasons and do not help with risk assessment for developing OIs. Tuberculin skin tests (TST) are used to check for immunity to tuberculosis (TB) and in the diagnosis of latent TB infection (LTBI). HIV-positive individuals are at a much higher risk of TB disease, but may also have a muted response to TST due to their compromised immunity. TST can be useful in assessing a patient’s eligibility for treatment with isoniazid preventive therapy but is not useful in assessing disease stage and risk of OIs in general. Diagnostic Tests for HIV-Related Immune Impairment

    • This question is part of the following fields:

      • Microbiology
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  • Question 11 - An 80-year-old woman presents to the Emergency Department with a 3-day history of...

    Incorrect

    • An 80-year-old woman presents to the Emergency Department with a 3-day history of fever, anorexia, and right upper quadrant pain. She appears lethargic and confused about her surroundings. Upon examination, there is significant tenderness in the abdomen, particularly in the right upper quadrant. What is the probable bacterial source of her infection?

      Your Answer:

      Correct Answer: Escherichia

      Explanation:

      Common Bacteria Associated with Cholecystitis

      Cholecystitis is a condition characterized by inflammation of the gallbladder. The most likely cause of this condition is Escherichia, a Gram-negative bacilli belonging to the Enterobacteriaceae family. Although Enterococcus can also cause cholecystitis, E Coli is more common. Bacteroides, an obligate anaerobic, Gram-negative bacterium, is a significant component of bacterial flora on mucous membranes but is not a common cause of cholecystitis. Pseudomonas, a Gram-negative aerobic bacterium, is a far less likely cause of acute cholecystitis and is associated with lung infections in those with underlying chronic lung pathology. Proteus, another member of the Enterobacteriaceae family, is a less likely cause of acute cholecystitis and is commonly associated with urinary tract infections. Understanding the common bacteria associated with cholecystitis can aid in the diagnosis and treatment of this condition.

    • This question is part of the following fields:

      • Microbiology
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  • Question 12 - A 13-year-old girl and her mother visit the GP to discuss the HPV...

    Incorrect

    • A 13-year-old girl and her mother visit the GP to discuss the HPV vaccine, Gardasil. The mother has concerns and wants to know which strains of HPV the vaccine targets.

      Your Answer:

      Correct Answer:

      Explanation:

      Understanding the Different Strains of HPV and Their Association with Cervical Cancer

      Human papillomavirus (HPV) is a common sexually transmitted infection that can lead to various health issues, including cervical cancer. However, not all strains of HPV are equally dangerous. Here is a breakdown of some of the most common strains and their association with cervical cancer:

      HPV 16 and 18 are the most concerning strains as they have the strongest association with cervical cancer. In fact, 70% of cervical cancers are caused by these two strains. This is why the HPV vaccination programme targets these strains.

      HPV 1 and 2 are associated with warts on the feet and hands, respectively, and are not strongly linked to cervical cancer.

      HPV 45 is a rare strain, and the current HPV vaccine provides protection against HPV 6, 11, 16, and 18 strains.

      HPV 31 and 33 are linked to cervical intra-epithelial neoplasia and have a high correlation with genital and oral cancers, but their link to cervical cancer is not as strong as HPV 16 and 18.

      HPV 52 and 58 are also linked to cancer, but their association with cervical cancer is not as strong as HPV 16 and 18.

      Understanding the different strains of HPV and their association with cervical cancer is crucial in preventing and managing this disease. Regular cervical cancer screenings and getting vaccinated against HPV can help reduce the risk of developing cervical cancer.

    • This question is part of the following fields:

      • Microbiology
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  • Question 13 - How would you describe a small RNA genome delta antigen virus that can...

    Incorrect

    • How would you describe a small RNA genome delta antigen virus that can only exist alongside hepatitis B?

      Your Answer:

      Correct Answer: Hepatitis D

      Explanation:

      Hepatitis D and Human Cytomegalovirus

      Hepatitis D is a virus that can only exist alongside another virus, specifically hepatitis B. Patients who are infected with both viruses have a higher risk of developing severe liver conditions such as hepatic failure, cirrhosis, and cancer. The mortality rate for those with both viruses is 20%, and it is more common in under-developed countries and among intravenous drug users.

      On the other hand, Human Cytomegalovirus (CMV) is a type of herpes virus that can remain latent in the body for many years. While a normal individual may not experience any symptoms, CMV can be life-threatening for those with weakened immune systems. HIV seropositive patients are unlikely to develop CMV disease unless their CD4 counts are less than 50. Diagnosis of CMV is typically done through whole blood CMV PCR.

      Overall, both hepatitis D and CMV are viruses that can have severe consequences for those who are infected, particularly for those with weakened immune systems. It is important to take preventative measures and seek medical attention if symptoms arise.

    • This question is part of the following fields:

      • Microbiology
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  • Question 14 - Which organism causing bacteraemia/sepsis necessitates the combined use of penicillin and an aminoglycoside...

    Incorrect

    • Which organism causing bacteraemia/sepsis necessitates the combined use of penicillin and an aminoglycoside for effective treatment?

      Your Answer:

      Correct Answer: Bacteroides fragilis

      Explanation:

      Antibiotic Treatment for Common Bacterial Infections

      Bacterial infections can be treated with antibiotics, but different types of bacteria require different antibiotics for effective treatment. Bacteroides fragilis, for example, requires a combination of penicillin and gentamicin to be adequately treated. On the other hand, Streptococcus pneumoniae can be treated with penicillin alone. Staphylococcus aureus, which can be resistant to certain antibiotics, is treated with flucloxacillin or vancomycin for resistant strains. Similarly, Enterococcus can be treated with a penicillin or vancomycin if it is resistant.

      It is important to note that the appropriate antibiotic treatment for a bacterial infection should be determined by a healthcare professional. Taking the wrong antibiotic or not completing a full course of antibiotics can lead to antibiotic resistance, which can make future infections more difficult to treat. Additionally, some antibiotics may have side effects or interact with other medications, so it is important to follow the instructions of a healthcare professional when taking antibiotics. By using antibiotics appropriately, we can effectively treat bacterial infections and prevent the development of antibiotic resistance.

    • This question is part of the following fields:

      • Microbiology
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  • Question 15 - A 55-year-old man was admitted to hospital for a cellulitis that had not...

    Incorrect

    • A 55-year-old man was admitted to hospital for a cellulitis that had not improved with empirical antibiotic treatment. He is currently taking warfarin for atrial fibrillation and is allergic to penicillin. During the course of his stay he developed a severe diarrhoea, and was put into a side-room after a stool sample returned positive for Clostridium difficile.
      Which antibiotic most likely contributed to his developing C. difficile?

      Your Answer:

      Correct Answer: Clindamycin

      Explanation:

      Antibiotics and C. difficile Infection: Understanding the Risks and Treatments

      C. difficile infection is commonly associated with the use of antibiotics, particularly clindamycin and second and third-gen Cephalosporins. Other antibiotics such as fluoroquinolones, penicillins, and co-amoxiclav are also linked to this infection. Risk factors include age, underlying health conditions, current use of PPIs, and prolonged antibiotic use. When C. difficile infection is confirmed, metronidazole is the initial treatment of choice, although mild cases may not require treatment. Severe cases may require vancomycin or fidaxomicin. Amoxicillin is also associated with C. difficile infection, while clarithromycin should not be prescribed to patients on warfarin. Ceftaroline, a new fifth-generation cephalosporin, has not yet been established as a risk factor for C. difficile infection. Understanding the risks and treatments associated with antibiotics and C. difficile infection is crucial for effective management and prevention.

    • This question is part of the following fields:

      • Microbiology
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  • Question 16 - A 35-year-old bird keeper in a zoo developed fever and difficulty breathing after...

    Incorrect

    • A 35-year-old bird keeper in a zoo developed fever and difficulty breathing after handling a new group of birds imported from Brazil. Which microorganism is likely to have caused his illness?

      Your Answer:

      Correct Answer: Chlamydia psittaci

      Explanation:

      Bacterial Infections and their Risk Factors

      Chlamydia psittaci, also known as ornithosis, is a bacterial infection that can be contracted through contact with exotic birds. The severity of the disease can range from no apparent illness to severe pneumonia, with additional symptoms such as diarrhea, arthralgia, meningitis, leukopenia, and Horder’s spots. Diagnosis is made through serology or bronchoalveolar lavage, and treatment involves tetracyclines or macrolides.

      Legionella pneumophila is typically transmitted through contaminated air conditioning systems and whirlpools, rather than through birds.

      Coxiella burnetii is usually contracted through exposure to infected cattle or cats, rather than birds.

      Rhodococcus is a Gram-positive organism that primarily affects individuals who are immunosuppressed, such as those with HIV infection.

      Klebsiella pneumonia is a Gram-negative organism that is commonly seen in individuals with weakened immune systems, including those with diabetes, alcoholism, liver disease, malignancy, or long-term steroid therapy.

      Understanding Bacterial Infections and their Risk Factors

    • This question is part of the following fields:

      • Microbiology
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  • Question 17 - A geriatric patient develops a wound infection postoperatively on the abdominal wall. This...

    Incorrect

    • A geriatric patient develops a wound infection postoperatively on the abdominal wall. This is swabbed, and 2 days later, the following report is available:
      Sample type: Pus from wound infection
      Culture report: Significant Staphylococcal species
      Sensitivities: Methicillin Sensitive
      Ciprofloxacin Resistant
      Tetracycline Resistant
      Trimethoprim Resistant
      Gentamicin Resistant
      Which of the following would you commence?

      Your Answer:

      Correct Answer: Flucloxacillin

      Explanation:

      Antibiotic Options for Staphylococcal Infections: A Review

      When it comes to treating staphylococcal infections, choosing the right antibiotic is crucial. Here, we review several options and their effectiveness against this type of bacteria.

      Flucloxacillin is a great choice for staphylococcal infections, as it has excellent activity against this type of bacteria. However, ciprofloxacin is not recommended, as staphylococci are typically resistant to it. Methicillin is the most effective option, but it is only used in the laboratory for testing antibiotic resistance. If the organism is resistant to methicillin, vancomycin may be necessary, but it is a broad-spectrum intravenous antibiotic that requires monitoring. Finally, trimethoprim is not a good choice for staphylococcal infections, as the bacteria are often resistant to it.

      In summary, choosing the right antibiotic for staphylococcal infections requires careful consideration of the available options and the specific characteristics of the infective organism.

    • This question is part of the following fields:

      • Microbiology
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  • Question 18 - A 30-year-old woman presents to you with complaints of dysuria, right flank pain...

    Incorrect

    • A 30-year-old woman presents to you with complaints of dysuria, right flank pain and suprapubic discomfort following her honeymoon. What is the most probable causative organism for her symptoms?

      Your Answer:

      Correct Answer: Escherichia coli

      Explanation:

      Bacterial Causes of Urinary Tract Infections

      Urinary tract infections (UTIs) and pyelonephritis are commonly caused by bacteria from the gastrointestinal tract. The most common causative agent is Escherichia coli, followed by Staphylococcus saprophyticus in young women. Serratia marcescens is less likely to cause UTIs as it is more commonly associated with hospital-acquired infections. Enterobacter cloacae is a less common cause of UTIs compared to E. coli. Proteus mirabilis, a highly motile organism that splits urea, can cause staghorn calculi if it chronically colonizes the urinary tract. Treatment usually involves a fluoroquinolone or sulfamethoxazole mixture with trimethoprim, but never moxifloxacin as it does not get into the urine. Understanding the bacterial causes of UTIs is crucial in selecting appropriate treatment options.

    • This question is part of the following fields:

      • Microbiology
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  • Question 19 - A 14-year-old boy with a history of sickle cell disease complains of worsening...

    Incorrect

    • A 14-year-old boy with a history of sickle cell disease complains of worsening pain in his left thigh and has a fever. An X-ray of the femur shows bone alterations indicative of osteomyelitis.
      What is the probable infectious agent responsible for this condition?

      Your Answer:

      Correct Answer: Salmonella enteritidis

      Explanation:

      Understanding the Causative Organisms of Osteomyelitis in Different Patient Populations

      Osteomyelitis is a complex condition that can be caused by a variety of organisms. In patients with sickle cell disease, salmonella enteritidis is the second most common causative organism, due to decreased immunity to encapsulated organisms. Staphylococcus aureus remains the most common causative organism overall. Gram-negative organisms, such as pseudomonas aeruginosa, are more commonly found in intravenous drug users and asplenic patients. Group B streptococci is a common causative agent in newborns, while proteus mirabilis is a rare causative organism in osteomyelitis. Escherichia coli is more commonly found in osteomyelitis occurring in asplenic patients and intravenous drug users. Diagnosis of osteomyelitis is complex and requires a combination of high clinical suspicion, raised inflammatory markers, and appropriate imaging investigations. Prolonged antibiotic therapy is often needed to successfully treat osteomyelitis, and early involvement of orthopaedic surgeons is useful, particularly in cases of chronic osteomyelitis.

    • This question is part of the following fields:

      • Microbiology
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  • Question 20 - What is the most frequent micro-organism responsible for haematogenous osteomyelitis? ...

    Incorrect

    • What is the most frequent micro-organism responsible for haematogenous osteomyelitis?

      Your Answer:

      Correct Answer: Staphylococcus aureus

      Explanation:

      Radiographic Abnormalities in Haematogenous Osteomyelitis

      Haematogenous osteomyelitis is a condition where infection spreads to the bone through the bloodstream. When the infection reaches the periosteal membrane, it can create a cloaca that extends into nearby soft tissues. This can lead to cortical sequestration. In children, the metaphysis may become infected and spread to the epiphysis, resulting in involucrum formation. Staphylococcus is a common cause of single or multiple Brodie’s abscesses, which appear as areas of radiolucency with adjacent sclerosis on X-rays. The lucent region in the metaphysis may connect with the growth plate through a tortuous channel, known as the channel or tract sign. In the diaphysis, the abscess cavity can be located in central or subcortical areas or in the cortex itself and may contain a central sequestrum. In the epiphysis, a circular, well-defined osteolytic lesion is seen. A cortical abscess can resemble the appearance of an osteoid osteoma or a stress fracture. These radiographic abnormalities can aid in the diagnosis of haematogenous osteomyelitis.

    • This question is part of the following fields:

      • Microbiology
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  • Question 21 - What is an example of an organism that can only survive inside a...

    Incorrect

    • What is an example of an organism that can only survive inside a host cell?

      Your Answer:

      Correct Answer: Chlamydia trachomatis

      Explanation:

      Chlamydia Trachomatis: A Unique Intracellular Parasite

      Chlamydia trachomatis is a type of intracellular parasite that infects only humans. Unlike other microorganisms, it cannot produce its own ATP or grow on artificial medium. Initially, it was believed to be a virus, but its unique developmental cycle led to its classification in a separate order. Diagnostic manuals often place it alongside other intracellular parasites like Rickettsiae.

      The genome size of Chlamydia trachomatis is around 500-1000 kilobases and contains both RNA and DNA. It is also highly temperature-sensitive and must be refrigerated at 4°C immediately after obtaining a sample.

    • This question is part of the following fields:

      • Microbiology
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  • Question 22 - A 16-year-old girl presents to the general practitioner, having noticed some swellings in...

    Incorrect

    • A 16-year-old girl presents to the general practitioner, having noticed some swellings in her left groin. She has recently acquired a cat and had a particularly nasty scratch on her left foot from it about 2 weeks earlier. She feels generally tired and unwell. On examination, she has a few swollen, tender left inguinal lymph nodes and some brownish papular discoloration around the site of the original scratch.
      Investigations:
      Investigation Result Normal value
      Haemoglobin 131 g/l 115–155 g/l
      White cell count (WCC) 5.3 × 109/l 4–11 × 109/l
      Platelets 180 × 109/l 150–400 × 109/l
      Erythrocyte sedimentation rate (ESR) 21 mm/hour 0–10mm in the 1st hour
      Sodium (Na+) 140 mmol/l 135–145 mmol/l
      Potassium (K+) 5.0 mmol/l 3.5–5.0 mmol/l
      Creatinine 100 μmol/l 50–120 µmol/l
      Which of the following is the most likely causative organism?

      Your Answer:

      Correct Answer: Bartonella henselae

      Explanation:

      Bacterial Infections: Causes and Symptoms

      Bacterial infections can cause a range of symptoms and affect different parts of the body. Here are some common bacterial infections and their associated symptoms:

      1. Bartonella henselae: This bacteria is responsible for cat scratch disease, which causes brownish-red papules around the site of inoculation. Other symptoms may include fever, malaise, and anorexia. Azithromycin is an effective antibiotic for treatment.

      2. Enterococcus faecalis: This Gram-positive bacteria is a commensal of the human gastrointestinal tract and can cause infections such as endocarditis, septicaemia, urinary tract infections, and meningitis.

      3. Campylobacter jejuni: This Gram-negative organism usually causes gastroenteritis symptoms such as diarrhoea, vomiting, and fever.

      4. Salmonella typhi: This bacteria causes typhoid fever, which presents as fever, weakness, abdominal pain, and constipation. It is usually spread through poor hygiene and public sanitation.

      5. Francisella tularensis: This Gram-negative rod-shaped aerobic bacteria causes tularaemia, which is contracted via contact with infected animal vectors such as mosquitos, ticks, and deer flies.

    • This question is part of the following fields:

      • Microbiology
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  • Question 23 - A patient presents with diarrhoea and vomiting; she is jaundiced. Hepatitis A infection...

    Incorrect

    • A patient presents with diarrhoea and vomiting; she is jaundiced. Hepatitis A infection is diagnosed.
      Which one of the following modes of transmission is most likely?

      Your Answer:

      Correct Answer: Contaminated food

      Explanation:

      Modes of Transmission for Hepatitis A Virus

      Hepatitis A virus is a self-limiting RNA virus that causes hepatitis. It is primarily acquired orally through contaminated food or water, or through contact with the feces of an infected individual. The incubation period is between two and six weeks, and symptoms may include flu-like and gastrointestinal symptoms during the prodromal phase, and jaundice, pruritus, fatigue, and hepatomegaly during the icteric phase. Unlike hepatitis B, C, D, and E, hepatitis A does not cause chronic infection and usually confers lifelong immunity.

      Mosquitoes and ticks do not transmit hepatitis A, but different mosquito species act as vectors for diseases such as malaria, dengue, chikungunya, and yellow fever, while hard and soft ticks transmit rickettsial infections like Rocky Mountain spotted fever. Hepatitis B, C, and D can be transmitted sexually, and hepatitis B, C, D, and E can be transmitted through blood transfusion. In rare cases, hepatitis A may also be transmitted sexually.

      Understanding the Modes of Transmission for Hepatitis A Virus

    • This question is part of the following fields:

      • Microbiology
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  • Question 24 - A 35-year-old business woman recently returned from a work conference in Turkey, where...

    Incorrect

    • A 35-year-old business woman recently returned from a work conference in Turkey, where she spent a lot of her time in air-conditioned conference rooms. She has a dry cough and a respiratory rate of 24. She also reports multiple episodes of vomiting and loose stools.
      What is the most likely causative organism of this patient symptom?

      Your Answer:

      Correct Answer: Legionella

      Explanation:

      Common Bacterial Causes of Pneumonia and their Characteristics

      Pneumonia is a common respiratory infection caused by various bacteria, including Legionella, Pseudomonas aeruginosa, Staphylococcus aureus, Pneumocystis jiroveci, and Mycoplasma. Each bacterium has its own unique characteristics and mode of transmission.

      Legionella is an atypical causative agent that spreads through air-conditioning systems. Patients with Legionella pneumonia typically present with a dry cough and may have hyponatremia and deranged liver function.

      Pseudomonas aeruginosa is most commonly seen in patients with aspiration pneumonia, cystic fibrosis, and bronchiectasis.

      Staphylococcus aureus is often seen after the flu, but the above travel and air-conditioning history makes it less likely to be the causative agent.

      Pneumocystis jiroveci is the most common opportunistic infection in AIDS patients.

      Mycoplasma is a cause of atypical pneumonia that often affects younger patients and is associated with erythema multiforme and cold autoimmune hemolytic anemia.

    • This question is part of the following fields:

      • Microbiology
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  • Question 25 - What is the cause of Ramsay Hunt syndrome? ...

    Incorrect

    • What is the cause of Ramsay Hunt syndrome?

      Your Answer:

      Correct Answer: HZV

      Explanation:

      Ramsay Hunt Syndrome: A Facial Paralysis Associated with Herpes Zoster

      Ramsay Hunt syndrome, also known as herpes zoster oticus or geniculate neuralgia, is a condition characterized by acute facial paralysis that occurs alongside herpetic blisters on the skin of the ear canal or auricle. This syndrome was first described by James Ramsay Hunt in 1907, who attributed the symptoms to an infection of the geniculate ganglion by the varicella-zoster virus (VZV).

      Patients with Ramsay Hunt syndrome typically experience otalgia (ear pain) along with cutaneous and mucosal rashes. The condition is caused by the reactivation of VZV, which lies dormant in the sensory ganglia after an initial infection with chickenpox. The virus can then travel along the sensory nerves to the skin of the ear, causing blisters and inflammation.

      Ramsay Hunt syndrome can be a debilitating condition, as the facial paralysis can affect a person’s ability to speak, eat, and drink. Treatment typically involves antiviral medication, corticosteroids, and supportive care to manage symptoms. Early diagnosis and treatment are important for improving outcomes and reducing the risk of complications.

    • This question is part of the following fields:

      • Microbiology
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  • Question 26 - A 30-year-old sexually active, unmarried man comes in with a painful sore on...

    Incorrect

    • A 30-year-old sexually active, unmarried man comes in with a painful sore on the glans of his penis. He reports experiencing discomfort and swelling in both of his groin areas. Upon examination, a tender ulcer with distinct, undermined borders that bleeds easily is discovered. Additionally, bilateral inguinal lymphadenopathy is observed during the examination, and a small sinus is visible above one of the lymph nodes, with pus easily expressed.

      What is the probable diagnosis?

      Your Answer:

      Correct Answer: Chancroid

      Explanation:

      Sexually Transmitted Diseases: Chancroid, Chlamydia, Syphilis, HIV, and gonorrhoeae

      Sexually transmitted diseases (STDs) are infections that are spread through sexual contact. Chancroid, caused by Haemophilus ducreyi, is a common STD that presents with painful genital ulcers and tender lymphadenopathy. Treatment involves a single dose of azithromycin. Chlamydia, caused by Chlamydia trachomatis, may be asymptomatic or present with penile/vaginal discharge or pain. Syphilis, on the other hand, presents with painless genital pustules that eventually ulcerate and does not typically involve lymphadenopathy. HIV, although associated with an increased risk of STDs, does not present with genital ulcers. gonorrhoeae, caused by Neisseria gonorrhoeae, usually presents with penile/vaginal discharge, dysuria, and pelvic pain, but can also be asymptomatic. It is important to practice safe sex and get tested regularly for STDs to prevent their spread.

    • This question is part of the following fields:

      • Microbiology
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  • Question 27 - A 40-year-old man with known human immunodeficiency virus (HIV) presents to the Emergency...

    Incorrect

    • 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:

      Correct 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.

    • This question is part of the following fields:

      • Microbiology
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  • Question 28 - A 27-year-old man presented to the Emergency Department with perineal pain. He has...

    Incorrect

    • A 27-year-old man presented to the Emergency Department with perineal pain. He has been experiencing excruciating pain while passing stool every morning for the past two weeks. He had previously been diagnosed with an anal fissure by a surgeon, but treatment failed to relieve his symptoms. He has also noticed streaks of blood in his stool. The patient recently returned from a trip to Tokyo. He appeared very distressed and reported continuous anal discharge leading to soiling of his undergarments for the past five days.
      What is the recommended treatment for this condition?

      Your Answer:

      Correct Answer: Single dose ceftriaxone

      Explanation:

      Treatment for Proctitis Syndrome: Single Dose Ceftriaxone

      Proctitis syndrome is a condition characterized by tenesmus, blood in stool, and anal discharge. It can be caused by infectious and non-infectious factors such as sexually transmitted diseases, Shigella, syphilis, Chlamydia, Crohn’s disease, and radiation proctitis. In this case, the patient has recently returned from a trip abroad, indicating the possibility of a sexually transmitted infection. Therefore, ceftriaxone is the appropriate treatment for gonorrhoeae, which is a common cause of proctitis.

      Probiotics are not indicated in the treatment of gonorrhoeae, and a steroid enema is only used if ulcerative colitis is suspected. Oral ciprofloxacin is not used in the treatment of gonorrhoeae but may be used for other conditions such as prostatitis or pyelonephritis. Surgical intervention is not necessary at this time but may be required later for the patient’s pre-existing anal fissure after recovery from proctitis.

    • This question is part of the following fields:

      • Microbiology
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  • Question 29 - A 45-year-old woman recently had a UTI, which was found to be positive...

    Incorrect

    • A 45-year-old woman recently had a UTI, which was found to be positive for Proteus mirabilis. What type of renal calculi is she now at a higher risk for developing?

      Your Answer:

      Correct Answer: Magnesium ammonium phosphate

      Explanation:

      Proteus mirabilis is a type of Gram-negative bacilli that can cause serious infections and is treated with broad-spectrum penicillins or cephalosporins. These organisms produce ureases, which can hydrolyze urea to ammonia and create an alkaline environment in urine. This can lead to the formation of magnesium ammonium phosphate stones, also known as struvite and staghorn calculi. However, Proteus mirabilis is not a risk factor for other types of kidney stones, such as urate, calcium oxalate, calcium phosphate, or cystine stones. These types of stones are caused by different factors, such as dehydration, hypercalcaemia, or genetic conditions. Treatment for each type of stone varies and may involve pain relief, medication, or surgery.

    • This question is part of the following fields:

      • Microbiology
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  • Question 30 - A 40-year-old intravenous drug user (ivDU) presents with fever, cough, and SOB. Upon...

    Incorrect

    • A 40-year-old intravenous drug user (ivDU) presents with fever, cough, and SOB. Upon echocardiogram, severe tricuspid regurgitation and two vegetations on the valve are observed. What is the most probable organism to be cultured from the patient's blood?

      Your Answer:

      Correct Answer: Staphylococcus aureus

      Explanation:

      Infective Endocarditis: Causes, Microbiology, and Clinical Features

      Infective endocarditis is a serious condition that can affect individuals with certain predisposing factors, such as a previous episode of endocarditis, rheumatic heart disease, intravenous drug use, prosthetic valves, congenital heart disease, and hypertrophic cardiomyopathy. The most common causative organisms include viridans streptococci, Streptococcus bovis, Staphylococcus aureus (especially in intravenous drug users), enterococcal, gram-negative bacteria, and Staphylococcus epidermidis (in patients with prosthetic valves).

      Clinical features of infective endocarditis include fever, anorexia and weight loss, new or changing murmur, splinter hemorrhages, clubbing, splenomegaly, petechiae, Osler’s nodes, Janeway’s lesions, Roth’s spots, systemic emboli, and hematuria. While 50% of cases occur in previously normal valves (native valve endocarditis), it is typically an acute presentation.

      Mycoplasma pneumoniae, Pneumocystis carinii (now known as Pneumocystis jirovecii), and Legionella pneumophila are not common causes of infective endocarditis. While Pseudomonas aeruginosa can cause infective endocarditis, it is less likely than S. aureus, especially in intravenous drug users.

    • This question is part of the following fields:

      • Microbiology
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