ID Consult

Children who are coughing: Is it flu or bacterial pneumonia?


 

We are in the middle of flu season, and many of our patients are coughing. Is it the flu or might the child have a secondary bacterial pneumonia? Let’s start with the history for a tip off. The course of flu and respiratory viral infections in general involves a typical pattern of timing for fever and cough.

coughing child DavidWhalen/Thinkstock

A late-developing fever or fever that subsides then recurs should raise concern. A prolonged cough or cough that subsides then recurs also should raise concern. The respiratory rate and chest retractions are key physical findings that can aid in distinguishing children with bacterial pneumonia. Rales and decreased breath sounds in lung segments are best heard with deep breaths.

What diagnostic laboratory and imaging tests should be used

Fortunately, rapid tests to detect influenza are available, and many providers have added those to their laboratory evaluation. A complete blood count and differential may be helpful. If a pulse oximeter is available, checking oxygen saturation might be helpful. The American Academy of Pediatrics community pneumonia guideline states that routine chest radiographs are not necessary for the confirmation of suspected community-acquired pneumonia (CAP) in patients well enough to be treated in the outpatient setting (Clin Inf Dis. 2011 Oct;53[7]:e25–e76). Blood cultures should not be performed routinely in nontoxic, fully immunized children with CAP managed in the outpatient setting.

What antibiotic should be used

Antimicrobial therapy is not routinely required for preschool-aged children with cough, even cough caused by CAP, because viral pathogens are responsible for the great majority of clinical disease. If the diagnosis of CAP is made, the AAP endorses amoxicillin as first-line therapy for previously healthy, appropriately immunized infants and preschool children with mild to moderate CAP suspected to be of bacterial origin. For previously healthy, appropriately immunized school-aged children and adolescents with mild to moderate CAP, amoxicillin is recommended for treatment of Streptococcus pneumoniae, the most prominent invasive bacterial pathogen.

However, the treatment paradigm is complicated because Mycoplasma pneumoniae also should be considered in management decisions. Children with signs and symptoms suspicious for M. pneumoniae should be tested to help guide antibiotic selection. This may be a simple bedside cold agglutinin test. The highest incidence of Mycoplasma pneumonia is in 5- to 20-year-olds (51% in 5- to 9-year-olds, 74% in 9- to 15-year-olds, and 3%-18% in adults with pneumonia), but 9% of CAP occurs in patients younger than 5 years old. The clinical features of Mycoplasma pneumonia resemble influenza: The patient has gradual onset of headache, malaise, fever, sore throat, and cough. Mycoplasma pneumonia has a similar incidence of productive cough, rales, and diarrhea as pneumococcal CAP, but with more frequent upper respiratory symptoms and a normal leukocyte count. Mycoplasma bronchopneumonia occurs 30 times more frequently than Mycoplasma lobar pneumonia. The radiologic features of Mycoplasma is typical of a bronchopneumonia, usually involving a single lobe, subsegmental atelectasis, peribronchial thickening, and streaky interstitial densities. While Mycoplasma pneumonia is usually self-limited, the duration of illness is shortened by oral treatment with doxycycline, erythromycin, clarithromycin, or azithromycin.

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