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The most common causative agents of bacterial meningitis are:
- A. Neisseria meningitidis
- B. Streptococcus pneumonia, Neisseria Meningitidis, hemophilus influenz
- C. Rubella virus
- D. Herpangina
Correct Answer: B
Rationale: The correct answer is B because Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae are the most common causative agents of bacterial meningitis. Streptococcus pneumoniae is a leading cause in adults, Neisseria meningitidis is common in adolescents and young adults, and Haemophilus influenzae is more frequent in children. The other choices, Rubella virus (C) and Herpangina (D), are not bacterial agents known to cause meningitis.
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Microscopic examination of a smear from a patient with diphtheria revealed dark blue-staining granules at the ends of rod-shaped bacteria. What staining technique was likely used?
- A. Neisser's staining
- B. Ziehl-Neelsen staining
- C. Gram staining
- D. Giemsa staining
Correct Answer: A
Rationale: The correct answer is A: Neisser's staining. Neisser's staining is used to detect metachromatic granules in bacteria, which appear as dark blue-staining granules at the ends of rod-shaped bacteria in diphtheria. This technique specifically targets these granules, making it ideal for identifying Corynebacterium diphtheriae, the causative agent of diphtheria. Ziehl-Neelsen staining is used for acid-fast bacteria like Mycobacterium tuberculosis, Gram staining is for classifying bacteria based on cell wall composition, and Giemsa staining is used for detecting parasites and certain blood cells, making them incorrect for identifying granules in diphtheria.
A 40-year-old man developed skin redness and swelling in the neck area, where eventually a small abscess appeared. On section the focus is dense and yellow-green colored, in the purulent masses there are white granules. Histologically there are fungal druses, plasma and xanthoma cells, and macrophages detected. Specify the most correct etiological name of this pathological process:
- A. Syphilis
- B. Carbuncle
- C. Actinomycosis
- D. Leprosy
Correct Answer: C
Rationale: The correct answer is C: Actinomycosis. Actinomycosis is a chronic suppurative bacterial infection caused by Actinomyces species, which form sulfur granules in purulent masses surrounded by dense fibrous tissue. In this case, the presence of fungal druses, plasma cells, xanthoma cells, and macrophages in the histological examination is characteristic of actinomycosis. The clinical presentation of skin redness, swelling, and abscess formation in the neck area also aligns with actinomycosis.
Choice A: Syphilis is caused by Treponema pallidum, presenting with a painless chancre at the site of infection, not skin redness and swelling in the neck area.
Choice B: Carbuncle is a bacterial skin infection involving a group of hair follicles, typically on the back of the neck, not characterized by fungal druses or sulfur granules.
Choice D: Leprosy
The most common cause of cystitis (after Escherichia coli) in healthy sexually active women is:
- A. Staphylococcus saprophyticus
- B. Proteus mirabilis
- C. Pseudomonas aeruginosa
- D. Klebsiella pneumoniae
Correct Answer: A
Rationale: The correct answer is A: Staphylococcus saprophyticus. This bacterium is the second most common cause of cystitis in healthy sexually active women after E. coli. Staphylococcus saprophyticus is commonly found in the gastrointestinal and genital areas. It has a unique ability to adhere to uroepithelial cells, making it a common pathogen in urinary tract infections. Proteus mirabilis is more commonly associated with complicated UTIs, especially in catheterized patients. Pseudomonas aeruginosa is more commonly seen in hospitalized or immunocompromised patients. Klebsiella pneumoniae is typically associated with UTIs in elderly patients or those with structural abnormalities in the urinary tract.
Microscopy of a sputum smear revealed acid-fast bacilli stained red using the Ziehl-Neelsen method. What is the most likely diagnosis?
- A. Tuberculosis
- B. Leprosy
- C. Diphtheria
- D. Pneumonia
Correct Answer: A
Rationale: The presence of acid-fast bacilli stained red using the Ziehl-Neelsen method indicates a mycobacterial infection. Among the choices, tuberculosis is the most common mycobacterial infection affecting the lungs, presenting with acid-fast bacilli in sputum. Leprosy is caused by Mycobacterium leprae, but it typically does not show up in sputum smears. Diphtheria is caused by Corynebacterium diphtheriae, which is not acid-fast. Pneumonia is a general term for lung inflammation caused by various pathogens, not specifically mycobacteria. Therefore, the correct diagnosis is tuberculosis based on the microscopy findings.
Which of the following microorganisms are always in a parasitic form of interaction with the individual?
- A. viruses
- B. non-pathogenic bacteria
- C. facultative pathogenic bacteria
- D. all listed above
Correct Answer: A
Rationale: The correct answer is A: viruses. Viruses are always in a parasitic form of interaction with the individual because they cannot survive or reproduce outside of a host cell. They rely on host cells to replicate and cause harm. Non-pathogenic bacteria (choice B) do not always cause harm and can coexist with the individual. Facultative pathogenic bacteria (choice C) can switch between being beneficial and harmful. Therefore, the correct answer is A as viruses always rely on a host for survival and reproduction.