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Chapter 38. Presentation and Management of Cystic Fibrosis

An 18-year-old cystic fibrosis patient is admitted to a medicine floor with marked increase in coughing, sputum production, and a recent history of fever. Auscultation reveals coarse inspiratory crackles in both bases posteriorly; SaO2 = 90% on room air by earlobe oximetry. A new chest radiograph shows infiltrates in the left lower lobe. The attending physician plans to start IV antibiotic therapy, but sputum cultures are not available yet. In addition to covering for infection with Pseudomonas aeruginosa, it will be most important to cover for possible infection by which of the following?

a. Klebsiella spp.

b. Haemophilus influenzae

c. Burkholderia cepacia

d. Staphylococcus aureus

e. Streptococcus pneumoniae

The most correct answer is d, S. aureus.

While virtually all of the other listed organisms can cause infections in CF patients, the possibility of this youth developing MRSA carries the greatest potential risk, particularly from nosocomial exposure while in the hospital. Klebsiella, H. influenzae, and B. cepacia, though potential pathogens in CF, are much less common than S. aureus.

A 15-year-old girl with cystic fibrosis complains of new onset nocturia and weight loss. Physical exam reveals mild digital clubbing. Her weight is at the 25th percentile for her age, but until now has always been at the 50th percentile. Her height is at the 50th percentile. Her cardiac, chest, and GI exams today are normal. What is the most likely explanation for nocturia in this patient?

a. Urinary tract infection

b. Congestive heart failure

c. Increased fluid intake

d. Impaired production of antidiuretic hormone

e. Onset of diabetes mellitus

The most correct answer is e.

The onset of CF-related DM due to endocrine pancreatic insufficiency develops in up to 10% of adolescent CF patients. Patients may present with weight loss (or fall in weight percentiles) and nocturia. A UTI in this girl (answer a) is certainly more likely than congestive heart failure (answer b) but would not present without pain or fever and would not be accompanied by weight loss. Fluid accumulation due to excessive intake or reduced ADH levels would likely be evident in both her physical exam and chest film (answers c and d).

A 12-year-old boy with CF presents to the emergency room with vomiting and crampy ...

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