The bacteria that causes whooping cough is:
- A. Bordetella pertussis
- B. Haemophilus influenzae
- C. Pseudomonas aeruginosa
- D. Streptococcus pneumoniae
Correct Answer: A
Rationale: The correct answer is A: Bordetella pertussis. Whooping cough is caused by this bacteria, which specifically infects the respiratory tract. Bordetella pertussis produces toxins that lead to the characteristic symptoms of the disease. Haemophilus influenzae, Pseudomonas aeruginosa, and Streptococcus pneumoniae are not the causative agents of whooping cough. Haemophilus influenzae can cause respiratory infections, Pseudomonas aeruginosa is associated with hospital-acquired infections, and Streptococcus pneumoniae is a common cause of pneumonia and other respiratory infections, but none of these bacteria are responsible for whooping cough.
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A smear of a patient's sputum suspected for tuberculosis was prepared and stained. The smear showed red bacilli against a blue background. What staining method was used?
- A. Ziehl-Neelsen
- B. Gram
- C. Giemsa
- D. Neisser
Correct Answer: A
Rationale: The correct answer is A: Ziehl-Neelsen staining method. This method is used to detect acid-fast bacteria like Mycobacterium tuberculosis. Step-by-step rationale: 1. Acid-fast bacteria resist decolorization with acid-alcohol. 2. The red bacilli seen in the smear indicate acid-fast bacteria. 3. Ziehl-Neelsen stain uses carbol fuchsin to stain acid-fast bacteria red. 4. The blue background is likely the counterstain methylene blue. Incorrect choices: B: Gram stain is for categorizing bacteria into Gram-positive or Gram-negative, not specific for acid-fast bacteria. C: Giemsa stain is used for blood films and detecting parasites, not acid-fast bacteria. D: Neisser stain is not a standard microbiological staining method.
Which bacteria is commonly associated with urinary tract infections (UTIs)?
- A. Escherichia coli
- B. Clostridium botulinum
- C. Staphylococcus aureus
- D. Bacillus cereus
Correct Answer: A
Rationale: The correct answer is A: Escherichia coli. E. coli is commonly associated with UTIs due to its ability to colonize the urinary tract. It possesses adhesins that allow it to attach to the bladder wall, causing infection. E. coli is also a common inhabitant of the intestinal tract, making it easily able to migrate to the urinary system.
Explanation of incorrect choices:
B: Clostridium botulinum - This bacterium causes botulism, a rare foodborne illness, not UTIs.
C: Staphylococcus aureus - Often associated with skin infections and abscesses, not UTIs.
D: Bacillus cereus - Known for causing food poisoning, not UTIs.
Which bacteria is responsible for causing the disease known as whooping cough?
- A. Clostridium botulinum
- B. Bordetella pertussis
- C. Streptococcus pneumoniae
- D. Neisseria meningitidis
Correct Answer: B
Rationale: The correct answer is B: Bordetella pertussis. This bacterium causes whooping cough by infecting the respiratory tract. It produces toxins that lead to severe coughing fits characteristic of the disease. Clostridium botulinum (A) causes botulism, Streptococcus pneumoniae (C) causes pneumonia, and Neisseria meningitidis (D) causes meningitis, not whooping cough. B. pertussis is the only bacterium specifically associated with whooping cough.
Allergies to sea food, eggs, etc are an example of:
- A. Type 1 hypersensitivity reaction
- B. Type 2 hypersensitivity reaction
- C. Type 3 hypersensitivity reaction
- D. Type 4 hypersensitivity reaction
Correct Answer: A
Rationale: The correct answer is A: Type 1 hypersensitivity reaction. In this type of reaction, allergens trigger the production of IgE antibodies, leading to mast cell and basophil degranulation and release of inflammatory mediators like histamine. This causes immediate allergic symptoms. Seafood and eggs are common allergens that can elicit this response.
B: Type 2 hypersensitivity reaction involves antibodies targeting cell surface or extracellular matrix antigens, leading to cell destruction or dysfunction. This is not the mechanism in seafood or egg allergies.
C: Type 3 hypersensitivity reaction involves immune complex deposition in tissues, leading to inflammation and tissue damage. This is not the mechanism in seafood or egg allergies.
D: Type 4 hypersensitivity reaction is cell-mediated and involves T cells causing inflammation and tissue damage. This is not the mechanism in seafood or egg allergies.
A duodenal content smear of a patient with indigestion contains protozoa 10-18 mcm large. They have piriform bodies, 4 pairs of filaments, two symmetrically located nuclei in the broadened part of body. What kind of the lowest organisms is it?
- A. Lamblia
- B. Dysentery ameba
- C. Trichomonas
- D. Intestinal ameba
Correct Answer: A
Rationale: The correct answer is A: Lamblia. The description matches the characteristics of Giardia lamblia - a protozoan parasite that causes giardiasis. The piriform bodies, 4 pairs of filaments, and two symmetrically located nuclei are specific to Giardia lamblia. It is important to differentiate it from the other choices. Dysentery ameba (choice B) typically has a single nucleus and lacks the specific characteristics described. Trichomonas (choice C) is a flagellated protozoan with different morphology and does not match the given description. Intestinal ameba (choice D) such as Entamoeba histolytica usually has a single nucleus and different body shape compared to the described organism.