Nokea
Which of the following methods is the simplest heat-related method to sterilize metal?
- A. Incineration
- B. Autoclaving
- C. Direct flaming
- D. Indirect heating
Correct Answer: C
Rationale: The correct answer is C: Direct flaming. Direct flaming is the simplest heat-related method to sterilize metal because it involves passing the metal through a flame to kill microorganisms. The high temperature of the flame effectively destroys any bacteria or spores present on the metal surface. Incineration (A) is not practical for sterilizing metal as it involves burning at extremely high temperatures. Autoclaving (B) uses steam under pressure to sterilize, which is effective but more complex than direct flaming. Indirect heating (D) is not an effective method for sterilizing metal as it does not directly expose the metal to high temperatures required for sterilization.
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Which of the following bacteria produce endotoxins that can lead to septic shock?
- A. Staphylococcus aureus
- B. Escherichia coli
- C. Pseudomonas aeruginosa
- D. All of the above
Correct Answer: D
Rationale: The correct answer is D because all three bacteria listed (Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa) can produce endotoxins that can lead to septic shock. Endotoxins are lipopolysaccharides found in the outer membrane of Gram-negative bacteria like E. coli and P. aeruginosa. Staphylococcus aureus, a Gram-positive bacterium, can also produce endotoxins called superantigens that can trigger a massive immune response leading to septic shock. Therefore, all of the above choices are correct. Choices A, B, and C alone are incorrect because they do not account for the fact that all three bacteria listed produce endotoxins that can cause septic shock.
Which of the following statements for S. Aureus is FALSE
- A. it is always susceptible for penicillin
- B. around its colonies there is a beta hemolytic zone
- C. it produces hemolysins, leucocidins, enterotoxins
- D. has a positive catalase reaction
Correct Answer: A
Rationale: The correct answer is A because Staphylococcus aureus can develop resistance to penicillin over time due to the production of beta-lactamase enzymes. This resistance mechanism makes it no longer susceptible to penicillin. The other choices are correct: B) S. aureus can produce beta hemolysis, C) it produces various toxins like hemolysins, leucocidins, and enterotoxins, and D) it shows a positive catalase reaction due to the presence of catalase enzyme that converts hydrogen peroxide to water and oxygen.
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.
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.
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.