Nokea
Nonchromosomal DNA molecules found in a bacterial cell are
- A. endospores.
- B. transposons.
- C. plasmids.
- D. prions.
Correct Answer: C
Rationale: The correct answer is C: plasmids. Plasmids are nonchromosomal DNA molecules commonly found in bacterial cells, providing additional genetic material for bacteria. They are not essential for bacterial survival but can confer advantages such as antibiotic resistance. Endospores (A) are dormant bacterial structures resistant to harsh conditions. Transposons (B) are mobile genetic elements that can move within a genome. Prions (D) are misfolded proteins causing neurodegenerative diseases, not DNA molecules.
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In the micropreparation made from patient's regional lymph node punctate and stained according to Romanovsky-Giemsa method, the doctor found out thin microorganisms with 12-14 equal ringlets and pale- pink sharp pointes 10-13 mkm in length. The pathogen of what disease is it about?
- A. Leishmaniasis
- B. Leptospirosis
- C. Surra
- D. Relapsing fever
Correct Answer: D
Rationale: The thin microorganisms described with 12-14 equal ringlets and pale-pink sharp points are characteristic of Borrelia spirochetes, the causative agent of relapsing fever. The ringlet appearance corresponds to the characteristic coiled structure of Borrelia spirochetes. The length of 10-13 mkm falls within the typical size range of Borrelia spirochetes. This pathogen is commonly identified in Romanovsky-Giemsa stained samples from patients with relapsing fever.
Summary of other choices:
A: Leishmaniasis - Leishmania parasites are larger and do not have the described ringlets or pale-pink sharp points.
B: Leptospirosis - Leptospira bacteria are not described as having ringlets or pale-pink sharp points.
C: Surra - Surra is caused by Trypanosoma evansi, and the description does not match the characteristics of this parasite.
The symmetry of nucleocapsid of poxviruses is:
- A. Complex
- B. Isohedral
- C. Helical
- D. All of the above
Correct Answer: A
Rationale: The correct answer is A: Complex. Poxviruses have a complex nucleocapsid symmetry due to their unique structure with multiple layers of proteins and genetic material. Isohedral symmetry (B) refers to a regular polyhedron shape, which is not characteristic of poxviruses. Helical symmetry (C) is found in viruses like tobacco mosaic virus, not poxviruses. "All of the above" (D) is incorrect because poxviruses do not exhibit isohedral or helical symmetry.
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.
Differentiating media are:
- A. Lowenstein-Jensen and Petraniani
- B. Apoholate-citrate aga and Brilliant-green phenol-red Lactose Agar
- C. Endo, Gassner and Levin
- D. None of the above
Correct Answer: C
Rationale: The correct answer is C because Endo, Gassner, and Levin are all examples of differential media used in microbiology. These media contain specific components that allow for the differentiation of different types of microorganisms based on their metabolic characteristics or biochemical reactions. Lowenstein-Jensen and Petraniani (choice A) are selective media for mycobacteria, not differential. Apoholate-citrate agar and Brilliant-green phenol-red Lactose agar (choice B) are selective media for Salmonella and E. coli, respectively, not differential. Therefore, the correct choice is C as it includes examples of differential media commonly used for microbial identification.
A 22-year-old patient is a clerk. His working day runs in a conditioned room. In summer he was taken by an acute disease with the following symptoms: fever, dyspnea, dry cough, pleural pain, myalgia, arthralgia. Objectively: moist rales on the right, pleural friction rub. X-ray picture showed infiltration of the inferior lobe. In blood: WBC - 11 · 109/l, stab neutrophils - 6%, segmented neutrophils - 70%, lymphocytes - 8%, ESR - 42 mm/h. What is the etiological factor pneumonia?
- A. Legionella
- B. Mycoplasma
- C. Streptococcus
- D. Staphylococcus
Correct Answer: C
Rationale: The correct answer is C: Streptococcus. Streptococcus pneumoniae is the most common etiological factor for community-acquired pneumonia in young adults. The symptoms described align with typical pneumococcal pneumonia presentation. Presence of pleural friction rub and infiltration in the X-ray support the diagnosis. The blood work showing elevated WBC count with a left shift (increased neutrophils and low lymphocytes) and elevated ESR is consistent with a bacterial infection. Legionella and Mycoplasma typically present with atypical pneumonia symptoms such as headache, confusion, and GI symptoms, which are not described in the case. Staphylococcus pneumonia is not a common cause of community-acquired pneumonia in young adults.