BCMH

A 6-year-old child presents with a low-grade fever, sore throat, and malaise. Over the next two days, a grayish, adherent pseudomembrane develops over the tonsils and pharynx, which bleeds on attempted removal. The child is unimmunized. The systemic effects of this infection, such as myocarditis and neuropathy, are mediated by a potent exotoxin that inhibits host cell protein synthesis through what specific molecular mechanism?

A 7-year-old child is brought to a rural clinic with multiple honey-coloured, crusted lesions around her nose and mouth, which started as small blisters. Some lesions are also present on her arms where she had minor scratches. The lesions are mildly itchy. She is otherwise well and afebrile.

What is the most likely diagnosis for these skin lesions?

A 40-year-old male farmer presents with a painless black eschar surrounded by significant edema on his right forearm. He reports handling animal hides a week prior. He is febrile and has tender regional lymphadenopathy. A Gram stain from the edge of the eschar reveals large, Gram-positive, spore-forming rods in chains. The organism is non-hemolytic on blood agar.

What is the most likely causative organism?

A group of people fall ill after sharing a meal that included a home-canned jar of vegetables at a community gathering. Twelve hours later, they develop symptoms including double vision, drooping eyelids, slurred speech, and progressing descending muscle weakness. Gastrointestinal symptoms like nausea were mild and preceded the neurological signs.

What microbial toxin is responsible for this clinical picture?

A cattle farmer from North West province presents with a large, painless, black-centred skin lesion (eschar) on his forearm, surrounded by significant oedema. He reports that the lesion started as a small, itchy papule a week ago. He has been otherwise well, with no cough or abdominal pain. Gram stain from the base of the eschar reveals large, Gram-positive, boxcar-shaped rods in chains.

What is the most likely diagnosis?

A 28-year-old woman, who is 10 weeks pregnant, presents to her antenatal clinic for her first visit. Routine screening blood tests are performed. Her rapid plasma reagin (RPR) test is reactive, and a subsequent Treponema pallidum particle agglutination (TPPA) test is also positive. She reports no symptoms or visible sores.

What is the most likely diagnosis?

A 19-year-old man sustains a deep laceration to his forearm from a contaminated piece of metal while working on a farm. Several days later, he develops increasing stiffness in his jaw (trismus), difficulty swallowing, and painful muscle spasms.

What is the most likely diagnosis?

A 25-year-old tourist who recently ate at a roadside food stall in Durban presents to the emergency department with acute-onset abdominal cramps, watery diarrhoea, and vomiting that began eight hours after his meal. His symptoms are intense but resolve spontaneously within 24 hours. Several other people who ate from the same stall report similar brief, violent illnesses.

Which gram-positive, spore-forming bacillus is the most likely culprit for this type of rapid-onset food poisoning?

A 25-year-old immunocompetent male develops watery diarrhea, abdominal cramps, and vomiting approximately 4 hours after consuming leftover fried rice from a buffet. The symptoms resolve within 24 hours without specific treatment. No fever or blood in the stool is reported. Several other people who ate the same rice also became ill.

Which pre-formed bacterial toxin, resistant to reheating, is the most likely cause of this rapid-onset food poisoning?

A 28-year-old pregnant woman in her third trimester is admitted to the labour ward with a fever, backache, and rigors. She is diagnosed with pyelonephritis. Her urine culture grows Gram-positive cocci in chains that exhibit beta-haemolysis on a blood agar plate. The laboratory performs a CAMP test, which is positive.

What is the most likely causative organism?

Which of the following are all fastidious Gram-Negative Bacteria: