A 13-year-old boy with cystic fibrosis comes to the clinic with a persistent cough over the past 2 weeks despite treatment with several oral antibiotics. Temperature is 36.7 C (98.1 F). Pulmonary examination reveals diffuse wheezing. Pulmonary function testing is consistent with an exacerbation of the underlying disease, and the patient is admitted for broad-spectrum intravenous antibiotics and aggressive respiratory therapy. Induced sputum is collected for cultures. In addition to blood, chocolate, and MacConkey agar, this patient's sputum should also be cultured on which of the following media?

Question

A 13-year-old boy with cystic fibrosis comes to the clinic with a persistent cough over the past 2 weeks despite treatment with several oral antibiotics.  Temperature is 36.7 C (98.1 F).  Pulmonary examination reveals diffuse wheezing.  Pulmonary function testing is consistent with an exacerbation of the underlying disease, and the patient is admitted for broad-spectrum intravenous antibiotics and aggressive respiratory therapy.  Induced sputum is collected for cultures.  In addition to blood, chocolate, and MacConkey agar, this patient's sputum should also be cultured on which of the following media?

Quizplus · Accepted Answer

11ec160b_381d_5348_9249_e9a3724a22fb_MD0001_00 Cystic fibrosis (CF) is an autosomal recessive disorder in which an abnormality in the CF transmembrane conductance regulator results in the accumulation of thick, viscous mucus in multiple organ systems. In particular, inspissated airway secretions block the respiratory tract and impair mucociliary clearance, leading to bacterial colonization and chronic, recurrent sinopulmonary infections. CF pulmonary exacerbations are characterized by a decline in lung function (ie, forced expiratory volume in 1 sec) and new or worsening cough, shortness of breath, or sputum production. Infection and subsequent airway inflammation are typically responsible for the acute change in respiratory status, and common bacterial pathogens include Staphylococcus aureus, nontypeable Haemophilus influenzae, and Pseudomonas aeruginosa. With progressive disease, however, patients are also at risk for colonization with Burkholderia cepacia complex, a fastidious gram-negative bacterium that is often difficult to eradicate and associated with increased morbidity and mortality. Sputum cultures are typically performed during CF pulmonary exacerbation to identify the pathogen and guide antimicrobial management. In addition to regular blood (eg, Streptococcus), chocolate (eg, H influenzae), and MacConkey (eg, Pseudomonas) agars, sputum should also be plated on mannitol salt agar (eg, S aureus) and B cepacia-selective agar. (Choices A, C, D, and E) Bordetella pertussis, Corynebacterium, Legionella, Salmonella, and Shigella do not commonly cause CF exacerbations. Educational objective: Patients with cystic fibrosis are at risk for pulmonary exacerbations due to Staphylococcus aureus, Pseudomonas aeruginosa, nontypeable Haemophilus influenzae, and Burkholderia cepacia complex. __________ References: Antibiotic treatment for Burkholderia cepacia complex in people with cystic fibrosis experiencing a pulmonary exacerbation. (http://www.ncbi.nlm.nih.gov/pubmed/26789750)

A 13-Year-Old Boy with Cystic Fibrosis Comes to the Clinic