A 42-year-old woman has foamy purulent vaginal discharges. Microscopy revealed flagellated protozoa with an undulating membrane and pear-shaped structure. What organism was found?

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Question 1 of 9

A 42-year-old woman has foamy purulent vaginal discharges. Microscopy revealed flagellated protozoa with an undulating membrane and pear-shaped structure. What organism was found?

Correct Answer: A

Rationale: The correct answer is A: Trichomonas vaginalis. Trichomonas vaginalis is a sexually transmitted protozoan parasite that causes trichomoniasis, characterized by foamy purulent vaginal discharges. Microscopy of vaginal discharge showing flagellated protozoa with an undulating membrane and pear-shaped structure is indicative of Trichomonas vaginalis. Trypanosoma gambiense causes African sleeping sickness and is transmitted by tsetse flies. Leishmania donovani causes visceral leishmaniasis transmitted by sandflies. Lamblia intestinalis causes giardiasis and is characterized by diarrhea and flatulence.

Question 2 of 9

Microscopic examination of a smear from a chancre revealed spiral microorganisms. The bacteria were thin and mobile with 8-12 regular coils. What is the likely diagnosis?

Correct Answer: A

Rationale: The correct diagnosis is A: Syphilis. The spiral microorganisms described are characteristic of Treponema pallidum, the causative agent of syphilis. The thin and mobile bacteria with 8-12 regular coils match the morphology of Treponema pallidum. Leptospirosis is caused by Leptospira interrogans, which are thicker and have hook-like ends, different from the described bacteria. Lyme disease is caused by Borrelia burgdorferi, which has a different appearance than the thin, coiled bacteria in the smear. Relapsing fever is caused by Borrelia recurrentis, which typically have irregular coils, unlike the regular coils seen in the smear.

Question 3 of 9

Gram-negative rods producing blue-green pigment and a fruity odor were isolated from a wound infection. What is the causative agent?

Correct Answer: A

Rationale: The correct answer is A: Pseudomonas aeruginosa. P. aeruginosa is known for producing a blue-green pigment called pyocyanin, which gives a characteristic color to the colonies. The fruity odor is due to the production of a compound called 2-aminoacetophenone by P. aeruginosa. These features are classic for P. aeruginosa and help differentiate it from other Gram-negative rods. Proteus mirabilis (B) typically does not produce blue-green pigment or fruity odor. Klebsiella pneumoniae (C) and Escherichia coli (D) also do not exhibit these specific characteristics associated with P. aeruginosa.

Question 4 of 9

A defined microorganism can be isolated in pure culture:

Correct Answer: C

Rationale: The correct answer is C because isolating a defined microorganism in pure culture involves obtaining a single, distinct colony on solid media. This ensures that only one type of microorganism is present in the culture, preventing contamination. Liquid media can harbor multiple organisms, making it challenging to isolate a specific microorganism. Therefore, choice A is incorrect. Choice B is also incorrect as liquid nutrient media does not provide the necessary isolation required for pure culture. Choice D is incorrect because isolating from single colonies on solid media allows for the pure culture of the defined microorganism.

Question 5 of 9

A 6-year-old boy is brought to the pediatrician by his mother, who complains of low-grade fever, chronic cough and night sweats in her child. She describes the cough as productive, producing white sputum that is sometimes streaked with blood. She also says that her son has lost some weight in the last month. His vital signs include blood pressure of 115/75 mm Hg, heart rate of 110/min., respiratory rate of 18/min. and temperature of 36,6°C. On physical examination, the patient is ill looking. Pulmonary auscultation reveals some fine crackles in the right upper lobe. The pediatrician suspects an active infection and performs Mantoux test. Intradermal injection of which of the following substances has been most likely used by pediatrician for screening test in this clinical case?

Correct Answer: A

Rationale: The correct answer is A: Tuberculin. In this clinical scenario, the patient presents with symptoms suggestive of tuberculosis, including chronic cough, night sweats, weight loss, and hemoptysis. The Mantoux test, also known as the tuberculin skin test, is used to screen for tuberculosis. Tuberculin, a purified protein derivative (PPD) derived from Mycobacterium tuberculosis, is injected intradermally. The test elicits a delayed-type hypersensitivity reaction in individuals who have been exposed to the organism in the past. A positive Mantoux test indicates exposure to tuberculosis and does not differentiate between active infection and prior exposure. Explanation for other choices: B: Measles - Measles is a viral infection that presents with a characteristic rash and fever, not consistent with the symptoms described in the case. C: Tetanus and diphtheria toxoids vaccine (Td) - Td vaccine is not used for tuberculosis screening and does not elicit

Question 6 of 9

The phagocytosis is:

Correct Answer: C

Rationale: The correct answer is C because phagocytosis refers to the process where certain host cells engulf and destroy microorganisms. This is an essential mechanism of the immune system to eliminate pathogens. Choice A is incorrect because phagocytosis does not involve the use of antibiotics. Choice B is incorrect as it describes a different mechanism of action against bacteria. Choice D is incorrect because phagocytosis is a well-established biological process.

Question 7 of 9

A patient has food poisoning. Laboratory analysis revealed a culture of anaerobic gram-positive spore-forming bacteria. What is the most likely kind of the isolated causative agent?

Correct Answer: A

Rationale: The correct answer is A: C. perfringens. This is because Clostridium perfringens is a gram-positive, anaerobic, spore-forming bacterium commonly associated with food poisoning. It produces toxins that cause gastrointestinal symptoms. Proteus vulgaris (B) and P. mirabilis (C) are gram-negative bacteria not typically associated with food poisoning. Vibrio parahemolyticus (D) is a gram-negative bacterium causing seafood-related gastroenteritis, not spore-forming or anaerobic.

Question 8 of 9

A patient with a long history of chronic gastritis undergoes a gastroscopy, which detects an ulcer in the duodenum area. Microscopic examination of the tissue biopsy developed Gram-negative curved bacteria and the rapid urease activity test of the biopsy material was highly positive. The most likely cause of the disease is:

Correct Answer: D

Rationale: The correct answer is D: Helicobacter pylori. Helicobacter pylori is a known bacterium associated with causing duodenal ulcers. The presence of Gram-negative curved bacteria in the biopsy along with a highly positive rapid urease test is characteristic of H. pylori infection. Vibrio cholerae causes cholera, not duodenal ulcers. Campylobacter fetus is associated with gastroenteritis, not duodenal ulcers. Acinetobacter baumannii is a nosocomial pathogen, not typically associated with duodenal ulcers. In summary, the unique combination of findings in this case points towards H. pylori as the most likely cause of the disease.

Question 9 of 9

The bacterium Yersinia pestis is responsible for causing what disease?

Correct Answer: C

Rationale: The correct answer is C: Plague. Yersinia pestis is the bacterium responsible for causing the bubonic, septicemic, and pneumonic plague. The bacterium is transmitted to humans through infected flea bites or handling infected animals. Tonsillitis (A) is commonly caused by streptococcal bacteria, leprosy (B) is caused by Mycobacterium leprae, and rat fever (D) is another term for leptospirosis, caused by Leptospira bacteria.

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