Nokea
Bacterial transformation involves:
- A. Transfer of plasmids through pili
- B. Uptake of naked DNA from the environment
- C. Transfer of DNA via bacteriophages
- D. Binary fission
Correct Answer: B
Rationale: The correct answer is B: Uptake of naked DNA from the environment. Bacterial transformation is a process where bacteria take up free DNA from their surroundings and incorporate it into their own genome. This process is essential for genetic recombination and the acquisition of new traits. Plasmids are small DNA molecules that can be transferred between bacteria, but not necessarily through pili. Bacteriophages are viruses that infect bacteria and transfer their DNA, but this is not the primary mechanism of bacterial transformation. Binary fission is a method of bacterial reproduction, not related to the uptake of DNA.
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Microscopic examination of a patient's duodenal contents revealed protozoa with two nuclei, four flagella, and a ventral adhesive disc. What is the likely causative agent?
- A. Giardia lamblia
- B. Leishmania donovani
- C. Entamoeba coli
- D. Trypanosoma gambiense
Correct Answer: A
Rationale: The correct answer is A: Giardia lamblia. This protozoan matches the description of the causative agent because it has two nuclei, four flagella, and a ventral adhesive disc. Giardia lamblia is commonly found in the duodenum and causes giardiasis. The other choices can be eliminated because Leishmania donovani causes visceral leishmaniasis, not the described symptoms. Entamoeba coli is a non-pathogenic amoeba found in the large intestine. Trypanosoma gambiense causes African trypanosomiasis and is transmitted by the tsetse fly, not matching the described characteristics.
Which of the following bacteria is responsible for causing bacterial meningitis?
- A. Neisseria meningitidis
- B. Haemophilus influenzae
- C. Streptococcus pneumoniae
- D. All of the above
Correct Answer: D
Rationale: The correct answer is D because all three bacteria (Neisseria meningitidis, Haemophilus influenzae, and Streptococcus pneumoniae) can cause bacterial meningitis. Neisseria meningitidis is a common cause of meningococcal meningitis, Haemophilus influenzae can cause H. influenzae meningitis, and Streptococcus pneumoniae is a leading cause of pneumococcal meningitis. Therefore, all of the above choices are correct. The other choices are incorrect because each of the bacteria listed can independently cause bacterial meningitis, so none of them alone can be the sole correct answer.
Which of the following bacteria is responsible for causing the plague?
- A. Yersinia pestis
- B. Clostridium difficile
- C. Neisseria gonorrhoeae
- D. Pseudomonas aeruginosa
Correct Answer: A
Rationale: The correct answer is A: Yersinia pestis. Y. pestis is responsible for causing the plague, a severe infectious disease. This bacterium is transmitted via fleas from rodents to humans. It causes bubonic, septicemic, and pneumonic plague. Clostridium difficile causes gastrointestinal infections, Neisseria gonorrhoeae causes gonorrhea, and Pseudomonas aeruginosa can cause various infections but not the plague.
A patient has wound abscess. Bacteriological examination of the wound content revealed a gram- negative bacillus which forms semi-transparent mucous colonies of blue-green color with a pearlescent appearance on the beef-extract agar. Culture has a specific odor of violets or jasmine. What type of pathogen was isolated from the patient's wound?
- A. P. aeruginosa
- B. P. vulgaris
- C. S. aureus
- D. S. pyogenes
Correct Answer: A
Rationale: Step 1: Gram-negative bacillus indicates P. aeruginosa, known for causing wound infections.
Step 2: Semi-transparent mucous colonies of blue-green color with a pearlescent appearance are characteristic of P. aeruginosa.
Step 3: Specific odor of violets or jasmine is a unique feature of P. aeruginosa.
Therefore, the correct answer is A: P. aeruginosa.
Summary:
- B: P. vulgaris typically forms yellow colonies and doesn't have the characteristic odor.
- C: S. aureus forms creamy white colonies, not blue-green, and has a distinct odor.
- D: S. pyogenes forms grayish-white colonies and doesn't have the unique characteristics described.
A 23 year old female patient complains about periodical chill and body temperature rise up to 40oC, sense of heat taking turns with profuse sweating. The patient has had already 3 attacks that came once in two days and lasted 12 hours. She has lived in Africa for the last 2 months. Liver and spleen are enlarged. In blood: erythrocytes - 2,5x1012/l. What is the most probable diagnosis?
- A. Malaria
- B. Spotted fever
- C. Sepsis
- D. Haemolytic anaemia
Correct Answer: A
Rationale: The most probable diagnosis is A: Malaria. The patient's symptoms of periodic chills, high fever, and profuse sweating, along with living in Africa where malaria is endemic, strongly suggest malaria. The enlarged liver and spleen are consistent with malaria infection. The low erythrocyte count indicates hemolysis, a common feature of malaria. Spotted fever and sepsis do not typically present with the same pattern of symptoms and travel history as seen in this case. Haemolytic anaemia would not explain the patient's fever episodes and other symptoms. Therefore, based on the symptoms, travel history, and laboratory findings, malaria is the most likely diagnosis.