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Which bacteria produce exotoxins that can cause severe dehydration and diarrhea?
- A. Vibrio cholerae
- B. Clostridium tetani
- C. Escherichia coli
- D. Shigella dysenteriae
Correct Answer: A
Rationale: The correct answer is A: Vibrio cholerae. This bacterium produces cholera toxin, an exotoxin that causes severe dehydration and diarrhea by increasing the secretion of electrolytes and water in the intestines. Vibrio cholerae is the causative agent of cholera, a disease characterized by profuse watery diarrhea. Choice B, Clostridium tetani, produces tetanospasmin causing tetanus, not dehydration or diarrhea. Choice C, Escherichia coli, can cause diarrhea but rarely severe dehydration. Choice D, Shigella dysenteriae, produces Shiga toxin leading to bloody diarrhea, not severe dehydration.
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A 43-year-old cattle farm worker is brought to the surgeon with fever, malaise, and inflamed lesions on his hands and arms. He reports that about 2 weeks before his presentation at the hospital he noticed small, painless, pruritic papules that quickly enlarged and developed a central vesicle. The vesicles developed into erosion and left painless necrotic ulcers with black, depressed eschar. Gram's staining of the ulcer reveals gram-positive spore-forming bacilli. Which of the following diseases is the most likely cause of these findings?
- A. Anthrax
- B. Chickenpox
- C. Syphilis
- D. Tularemia
Correct Answer: A
Rationale: The correct answer is A: Anthrax. The clinical presentation of painless necrotic ulcers with black eschar, along with the gram-positive spore-forming bacilli seen on Gram's staining, is classic for cutaneous anthrax. Anthrax is caused by Bacillus anthracis, which produces spores and can lead to skin lesions in individuals working with animals or animal products. Choice B, Chickenpox, typically presents with vesicular rash all over the body. Choice C, Syphilis, is caused by Treponema pallidum and does not present with the characteristic eschar seen in the patient. Choice D, Tularemia, caused by Francisella tularensis, presents with ulceroglandular lesions but lacks the black eschar characteristic of anthrax.
Which are the most suitable materials for isolation of polio viruses
- A. feces, duodenal and bile content
- B. blood, sputum and urine
- C. only feces
- D. feces, nasopharyngeal swabs and cerebrospinal fluid
Correct Answer: D
Rationale: The correct answer is D because polio viruses are primarily found in the gastrointestinal tract and respiratory secretions. Feces, nasopharyngeal swabs, and cerebrospinal fluid are the most suitable materials for isolating polio viruses due to their presence in these body fluids. Feces contain the virus shed from the intestines, nasopharyngeal swabs collect respiratory secretions where the virus may be present, and cerebrospinal fluid is important for detecting the virus in cases of neurological complications. Choices A and B include irrelevant body fluids that are not typically associated with polio virus transmission. Option C is too limited as the virus can also be present in respiratory secretions and cerebrospinal fluid, not just feces.
Factors that can increase the chances of vaginitis are:
- A. urinary blockage, drug use, and stress
- B. use of antibiotics, pregnancy, and menopause
- C. puberty, exposure to HPV, and smoking/tobacco use
- D. menopause, stress, and steroid use
Correct Answer: B
Rationale: The correct answer is B. Vaginitis is often caused by an imbalance in vaginal flora. Antibiotics can disrupt the natural balance, leading to overgrowth of harmful bacteria or yeast. Pregnancy alters hormone levels, making the vagina more susceptible to infection. Menopause decreases estrogen levels, thinning the vaginal walls and reducing beneficial bacteria.
A: Urinary blockage does not directly relate to vaginitis. Drug use and stress may weaken the immune system but are not direct causes of vaginitis.
C: Puberty, HPV exposure, and smoking/tobacco use do not directly increase the chances of vaginitis. HPV is a viral infection, not a direct cause of vaginitis.
D: While menopause can increase the risk of vaginitis due to hormonal changes, stress and steroid use are not primary factors in developing vaginitis.
A patient with fever and enlarged lymph nodes had a blood smear examined under the microscope. Spiral microorganisms with pointed ends were detected. What is the likely diagnosis?
- A. Syphilis
- B. Leptospirosis
- C. Lyme disease
- D. Relapsing fever
Correct Answer: A
Rationale: Rationale: The correct answer is A: Syphilis. Spiral microorganisms with pointed ends are characteristic of Treponema pallidum, the causative agent of syphilis. This bacterium is known for its corkscrew shape. Other choices are incorrect because Leptospirosis, Lyme disease, and Relapsing fever are caused by different pathogens and do not exhibit spiral microorganisms on blood smears. Syphilis should be suspected in the presence of these specific spiral microorganisms.
A 45-year-old patient complains of fever up to 40oC, general weakness, headache and spasmodic contraction of muscles in the region of a shin wound. The patient got injured five days ago when tilling soil and didn't seek medical attention. What kind of wound infection can be suspected?
- A. Tetanus
- B. Anthrax
- C. Erysipelas
- D. Gram-positive
Correct Answer: A
Rationale: Step 1: The patient's symptoms align with tetanus infection, such as muscle spasms and fever.
Step 2: Tetanus is caused by Clostridium tetani bacteria found in soil.
Step 3: The wound from tilling soil provides an entry point for the bacteria.
Step 4: Delayed seeking medical attention increases the risk of tetanus development.
Step 5: Tetanus toxin affects the nervous system, leading to muscle stiffness and spasms.
Summary: Choice A is correct due to symptom alignment, bacterial source, wound type, delayed treatment, and specific neurological effects. Choices B, C, and D lack these specific connections to the given scenario.