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Which of the following is the most common cause of neonatal meningitis?
- A. Haemophilus influenzae b
- B. Streptococcus agalactiae
- C. Neisseria meningitidis
- D. Streptococcus pneumoniae
Correct Answer: B
Rationale: The correct answer is B: Streptococcus agalactiae. This bacterium is the most common cause of neonatal meningitis due to its ability to colonize the maternal genital tract and be transmitted to the newborn during delivery. It is a leading cause of early-onset neonatal sepsis and meningitis. Haemophilus influenzae b, Neisseria meningitidis, and Streptococcus pneumoniae are more commonly associated with meningitis in older children and adults, rather than in neonates. Therefore, choice B is the most appropriate answer based on the specific context of neonatal meningitis.
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A lumbar puncture is performed on a child suspected of having bacterial meningitis. CSF is obtained for analysis. A nurse reviews the results of the CSF analysis and determines that which of the following results would verify the diagnosis?
- A. Cloudy CSF, decreased protein, and decreased glucose
- B. Cloudy CSF, elevated protein, and decreased glucose
- C. Clear CSF, elevated protein, and decreased glucose
- D. Clear CSF, decreased pressure, and elevated protein
Correct Answer: B
Rationale: Bacterial meningitis is characterized by cloudy CSF due to the presence of white blood cells, elevated protein levels, and decreased glucose levels. These findings result from the inflammatory response to bacterial infection in the meninges. Confirming these results is critical for initiating appropriate antibiotic therapy.
A 33-year-old female presents with drooping of her eyelid that seem to occur while reading or watching television. This appears to get worse later in the day. She also reports that at times she sees "double." A few weeks ago, she was prescribed an antibiotic medication for a urinary tract infection. She does not recall the name of the antibiotic. On physical exam, bilateral ptosis, with the left affected more than the right is seen. Pupillary function intact. A glove is filled with ice, and subsequently applied to the patient's eyelid. After two minutes, the patient's ptosis has improved. Which of the following is most likely to yield rapid symptom improvement?
- A. Corticosteroids
- B. Plasma exchange
- C. Acetylcholinesterase inhibitor
- D. Thymectomy
Correct Answer: C
Rationale: The patient's symptoms of ptosis and diplopia that worsen with activity and improve with rest are classic for myasthenia gravis. The ice pack test, which improves ptosis, further supports this diagnosis. Acetylcholinesterase inhibitors, such as pyridostigmine, are the first-line treatment for symptomatic improvement in myasthenia gravis. Corticosteroids and plasma exchange are used for long-term management or severe cases, while thymectomy is a surgical option for thymoma-associated myasthenia gravis.
A patient is being evaluated for an acute onset of a high fever, severe headache, vomiting, and a change in mental status. Which assessment finding would confirm a definitive diagnosis of meningitis?
- A. Initial Glasgow Coma Scale score <15
- B. Pseudomonas aeruginosa on blood culture
- C. Normal MRI
- D. White blood cells (WBC) in cerebrospinal fluid (CSF)
Correct Answer: D
Rationale: The correct answer is D: White blood cells (WBC) in cerebrospinal fluid (CSF). In meningitis, an infection of the meninges, the CSF will show an elevated WBC count indicating an inflammatory response. This finding is crucial for confirming the diagnosis as it directly reflects the presence of infection in the central nervous system.
A: While a Glasgow Coma Scale score <15 may indicate altered mental status, it is not specific to meningitis.
B: Pseudomonas aeruginosa on blood culture suggests a bacterial infection but does not confirm meningitis specifically.
C: A normal MRI may not show definitive signs of meningitis, as the diagnosis is primarily made through CSF analysis.
Deuterium oxide and inulin are injected into a normal 30-year-old man. The volume of distribution of deuterium oxide is found to be 42 L and that of inulin 14 L.
- A. The man's intracellular fluid volume is about 14 L.
- B. The man's intracellular fluid volume is about 28 L.
- C. The man's plasma volume is about 7 L.
- D. The man's interstitial fluid volume is about 9 L.
Correct Answer: B
Rationale: Deuterium oxide distributes throughout total body water (TBW), while inulin distributes only in extracellular fluid (ECF). The intracellular fluid (ICF) volume is calculated as TBW - ECF. Here, TBW = 42 L and ECF = 14 L, so ICF = 42 - 14 = 28 L. This calculation is based on the principle that deuterium oxide measures all body water, while inulin is restricted to the extracellular compartment.
Millions of sensory receptors detect changes, called ________, which occur inside and outside the body.
- A. neuron
- B. skin
- C. motor
- D. stimuli
Correct Answer: D
Rationale: Sensory receptors detect changes, known as stimuli, which occur both inside and outside the body. These stimuli can include temperature, pressure, light, and chemical changes. Neurons are the cells that transmit these signals, while the skin is an organ that contains sensory receptors. Motor refers to the output of the nervous system, such as muscle movement. Stimuli is the correct answer as it refers to the changes detected by sensory receptors.