Nokea
The cell envelope of Gram-negative bacteria is composed of:
- A. Cytoplasmic membrane, a peptidoglycan layer and an outer membrane
- B. Cytoplasmic membrane and peptidoglycan layer
- C. Only peptidoglycan layer
- D. None of the above
Correct Answer: A
Rationale: The correct answer is A because Gram-negative bacteria have a unique cell envelope structure consisting of a cytoplasmic membrane, a peptidoglycan layer, and an outer membrane. The cytoplasmic membrane is the innermost layer that separates the cytoplasm from the external environment. The peptidoglycan layer provides structural support to the cell. The outer membrane acts as an additional protective barrier and contains lipopolysaccharides. Choice B is incorrect because Gram-negative bacteria have an outer membrane in addition to the cytoplasmic membrane and peptidoglycan layer. Choice C is incorrect because Gram-negative bacteria have more than just a peptidoglycan layer in their cell envelope. Choice D is incorrect as the cell envelope of Gram-negative bacteria does have specific components.
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Rheumatic fever is an inflammatory disease and rare complication of:
- A. strep throat
- B. gangrene
- C. brucellosis
- D. tularemia
Correct Answer: A
Rationale: Rheumatic fever is caused by untreated strep throat. Step 1: Strep throat is caused by Streptococcus bacteria. Step 2: If strep throat is not treated with antibiotics, it may lead to rheumatic fever due to the body's immune response attacking its own tissues. Summary: Gangrene, brucellosis, and tularemia are not associated with rheumatic fever.
A source of hospital-acquired infection could be:
- A. New patients in incubation period
- B. Medical staff
- C. Medical instruments
- D. All are correct
Correct Answer: D
Rationale: The correct answer is D because all the choices can contribute to hospital-acquired infections. New patients in the incubation period can spread infections, medical staff can inadvertently transmit infections, and contaminated medical instruments can also be a source of infections. Therefore, it is important to consider all these factors to prevent and control the spread of infections in a hospital setting.
A 45-year-old patient, a sailor, was hospitalized on the 2nd day of the disease. A week ago he returned from India. Complains of body temperature of 41oC, severe headache, dyspnea, cough with frothy rusty sputum. Objectively: the patient is pale, mucous membranes are cyanotic, breathing rate - 24/min, tachycardia is present. In lungs: diminished breath sounds, moist rales over both lungs, crepitation. What is the most likely diagnosis?
- A. Pneumonic plaque
- B. Miliary tuberculosis
- C. Influenza
- D. Ornithosis
Correct Answer: A
Rationale: The most likely diagnosis is A: Pneumonic plague. The patient's symptoms align with the presentation of pneumonic plague, caused by the bacterium Yersinia pestis. Symptoms include high fever, severe headache, dyspnea, cough with bloody sputum, and cyanosis. The characteristic bubonic plague lymphadenopathy may be absent in the pneumonic form. The patient's recent travel history to India also raises suspicion, as plague is endemic in some regions. The other choices can be ruled out based on the patient's symptoms and presentation. Miliary tuberculosis typically presents with diffuse miliary nodules on imaging. Influenza typically presents with more generalized symptoms and does not usually cause rusty sputum. Ornithosis is caused by Chlamydophila psittaci and usually presents with pneumonia-like symptoms after exposure to infected birds.
What is the function of bacterial fimbriae?
- A. Adhesion to surfaces
- B. DNA replication
- C. Protein synthesis
- D. Flagella movement
Correct Answer: A
Rationale: The correct answer is A: Adhesion to surfaces. Bacterial fimbriae are hair-like appendages that help bacteria attach to surfaces, such as host cells or medical devices. This adhesion is crucial for colonization and infection. DNA replication (B) occurs in the cell's nucleus, not on the surface. Protein synthesis (C) happens inside the cell, not on the fimbriae. Flagella movement (D) is the function of flagella, not fimbriae.
Microscopy of a smear taken from the film that appeared on the peptone water 6 hours after seeding and culturing of a fecal sample in a thermostat revealed mobile gram-negative bacteria curved in form of a comma that didn't make spores or capsules. What microorganisms were revealed?
- A. Vibrios
- B. Spirochetes
- C. Clostridia
- D. Corynebacteria
Correct Answer: A
Rationale: The correct answer is A: Vibrios. Vibrios are gram-negative curved bacteria that are motile and do not form spores or capsules. The description of the bacteria in the question fits the characteristics of Vibrios. Vibrios are commonly found in aquatic environments and some species can cause gastrointestinal infections in humans.
B: Spirochetes are also gram-negative curved bacteria, but they are spiral-shaped and have unique axial filaments for motility. The description in the question does not match the characteristics of spirochetes.
C: Clostridia are gram-positive, spore-forming bacteria. The question specifically states that the bacteria are gram-negative and do not form spores, ruling out Clostridia.
D: Corynebacteria are gram-positive, non-spore-forming bacteria. The description in the question does not match the characteristics of Corynebacteria.