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Which type of bacteria are capable of surviving in high salt concentrations?
- A. Acidophiles
- B. Thermophiles
- C. Halophiles
- D. Mesophiles
Correct Answer: C
Rationale: Correct Answer: C: Halophiles
Rationale:
1. Halophiles are bacteria adapted to high salt environments.
2. They have specific mechanisms to tolerate high salt concentrations.
3. Acidophiles thrive in acidic conditions.
4. Thermophiles prefer high temperature environments.
5. Mesophiles grow best at moderate temperatures.
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A 38-year-old male complains of tonic tension of the masticatory muscles, so that he cannot open his mouth. 12 days before, he was bitten by an unknown dog. Objectively: there is pronounced tension and twitching of the masticatory muscles. What is the most likely diagnosis?
- A. Tetanus
- B. Rabies
- C. Hysteria
- D. Trigeminal neuralgia
Correct Answer: A
Rationale: The correct answer is A: Tetanus. The symptoms of tonic tension of the masticatory muscles following a dog bite are indicative of tetanus, caused by the bacterium Clostridium tetani. The incubation period of tetanus is usually 3-21 days, consistent with the patient's history of being bitten 12 days ago. Tetanus toxin causes muscle stiffness and spasms, leading to the inability to open the mouth. Rabies (B) presents with hydrophobia and neurological symptoms. Hysteria (C) is a psychological condition. Trigeminal neuralgia (D) is characterized by severe facial pain, not muscle stiffness.
According to the location of flagella on their surface, bacteria can be:
- A. Monotrichous
- B. Amphitrichous
- C. Peritrichous
- D. All of these
Correct Answer: D
Rationale: The correct answer is D, "All of these." Monotrichous bacteria have a single flagellum at one end, amphitrichous have flagella at both ends, and peritrichous have flagella distributed all over the surface. The answer D is correct because it includes all these possibilities based on flagella location. Monotrichous is incorrect as it only refers to a single flagellum, amphitrichous is incorrect as it only refers to flagella at both ends, and peritrichous is incorrect as it only refers to flagella all over the surface. Therefore, the correct answer encompasses all these options.
Etiological cause of bacteremia could be:
- A. S.epidermidis, E.coli, S. aureus
- B. P.aeruginosa, K. pneumoniae, E.coli
- C. Resident skin diphtheroids
- D. All of the above
Correct Answer: D
Rationale: The correct answer is D because bacteremia can be caused by a variety of bacteria including S.epidermidis, E.coli, S.aureus, P.aeruginosa, K.pneumoniae, and resident skin diphtheroids. Bacteremia refers to the presence of bacteria in the bloodstream, which can occur due to infections from various sources. Choices A and B include common bacteria known to cause bacteremia, while choice C refers to resident skin diphtheroids that can also enter the bloodstream under certain conditions. Therefore, the correct answer is D as it encompasses all the possible etiological causes of bacteremia.
A sputum smear from a patient with pneumonia revealed Gram-positive cocci in pairs with pointed ends and capsules. What is the likely microorganism?
- A. Streptococcus pneumoniae
- B. Staphylococcus aureus
- C. Klebsiella pneumoniae
- D. Neisseria meningitidis
Correct Answer: A
Rationale: The correct answer is A: Streptococcus pneumoniae. The description of Gram-positive cocci in pairs with pointed ends and capsules matches the morphology of S. pneumoniae. This bacterium is known to cause pneumonia, especially in individuals with underlying conditions like COPD. Staphylococcus aureus (B) typically appears in clusters, not pairs. Klebsiella pneumoniae (C) is a Gram-negative rod, not a cocci. Neisseria meningitidis (D) is a Gram-negative diplococcus, not a cocci. Hence, based on the morphology and clinical context, Streptococcus pneumoniae is the likely microorganism causing pneumonia in this patient.
A 12-year-old boy presents with nausea, frequent repeated vomiting that first occurred after eating canned vegetables. Objectively: the patient has dry mucous membranes, muscular hypotonia, anisocoria, mydriasis, dysphagia and dysarthria. What is the most likely diagnosis?
- A. Botulism
- B. Shigellosis
- C. Salmonellosis
- D. Cholera
Correct Answer: A
Rationale: The most likely diagnosis is A: Botulism. The symptoms, such as nausea, vomiting after eating canned vegetables, dry mucous membranes, muscular hypotonia, anisocoria, mydriasis, dysphagia, and dysarthria, are classic signs of botulism poisoning. Botulism is caused by the neurotoxin produced by Clostridium botulinum bacteria found in improperly canned or preserved food. The neurotoxin affects the nervous system, leading to symptoms like those described. Shigellosis (B), Salmonellosis (C), and Cholera (D) typically present with different symptoms such as diarrhea, fever, and abdominal pain, which are not seen in this patient.