A 9-year-old boy is brought to the emergency department for a worsening cough. Two weeks ago, he developed rhinorrhea, congestion, and a mild cough. Since then, the cough has worsened, particularly at night and during exertion, and he often vomits after a bout of coughing. The patient has no chronic medical conditions. Temperature is 37.2 C (99 F), blood pressure is 90/60 mm Hg, pulse is 98/min, and respirations are 20/min. Pulse oximetry shows an oxygen saturation of 98%. On physical examination, the child is alert and well-appearing. Bilateral subconjunctival hemorrhages and periorbital petechiae are noted. The lungs are clear to auscultation. Which of the following organisms is the most likely cause of this patient's illness?

Question

A 9-year-old boy is brought to the emergency department for a worsening cough.  Two weeks ago, he developed rhinorrhea, congestion, and a mild cough.  Since then, the cough has worsened, particularly at night and during exertion, and he often vomits after a bout of coughing.  The patient has no chronic medical conditions.  Temperature is 37.2 C (99 F), blood pressure is 90/60 mm Hg, pulse is 98/min, and respirations are 20/min.  Pulse oximetry shows an oxygen saturation of 98%.  On physical examination, the child is alert and well-appearing.  Bilateral subconjunctival hemorrhages and periorbital petechiae are noted.  The lungs are clear to auscultation.  Which of the following organisms is the most likely cause of this patient's illness?

Quizplus · Accepted Answer

11ec25c8_d284_fbb8_bc81_0bf40f6ead4c_MD0003_00 Bordetella pertussis is a gram-negative coccobacillus that causes whooping cough, a highly contagious illness. The illness begins with a catarrhal phase resembling the common cold (eg, mild cough, rhinorrhea) that lasts 1-2 weeks. This is followed by the paroxysmal phase in which severe, periodic coughing episodes can last up to 30 minutes. These paroxysms may be more frequent at night or exacerbated by activities such as exercise, laughing, or yawning. Forceful coughing often triggers posttussive emesis and may result in facial petechiae and/or subconjunctival hemorrhages because the increased intrathoracic pressure leads to capillary hemorrhage. Coughing episodes may be followed by a whoop sound caused by forced inspiration, especially in infants and unvaccinated children. Patients can appear remarkably well between coughing spells. However, infants age <6 months are at risk for life-threatening apnea and death. Prevention is best achieved by immunization with acellular pertussis at age 2, 4, 6, and 15-18 months and 4-6 years, with a booster dose at age 11-12. Vaccination, however, does not confer lifelong protection because immunity wanes over time. Therefore, documentation of appropriate vaccination does not exclude a diagnosis of pertussis. (Choice A) Adenovirus causes a common, acute upper respiratory infection in children; it is often accompanied by fever, pharyngitis, conjunctivitis, and diarrhea. Coughing paroxysms are not typical. (Choice C) Influenza virus infection presents acutely with upper respiratory symptoms (eg, cough), in addition to fever, headache, and myalgias. Prolonged symptoms in this afebrile child make influenza unlikely. (Choice D) Nontypeable Haemophilus influenzae, a cause of community-acquired pneumonia in children, presents with acute fever, cough, and tachypnea. Paroxysmal coughing is not typical. (Choice E) Parainfluenza virus is a common cause of laryngotracheobronchitis (croup) in children. Croup classically presents acutely with a barky cough and inspiratory stridor, neither of which is present in this patient. (Choice F) Respiratory syncytial virus is the most common cause of bronchiolitis in children age <2. Symptoms include acute fever, rhinorrhea, cough, and respiratory distress. Wheezing is often present on examination. Educational objective: Bordetella pertussis causes whooping cough, a vaccine-preventable disease characterized by severe coughing episodes, which are often associated with posttussive emesis and an inspiratory whoop. Physical examination may reveal evidence of increased capillary pressure (eg, facial petechiae, subconjunctival hemorrhage). References: Pertussis (whooping cough). (http://www.ncbi.nlm.nih.gov/pubmed/30085550)

A 9-Year-Old Boy Is Brought to the Emergency Department for a Worsening