HISTORY OF PRESENT ILLNESS
The patient is a 3-year-old girl who was brought to the emergency department crying and clutching her chest. She was extremely difficult to console. She had poor oral intake during the last day with decreased urine output. On the evening of admission, she was found sitting in bed whimpering and holding her chest. She did not have a history of vomiting or diarrhea. Her temperature had not been measured but she did not feel subjectively warm.
The girl had been seen in the emergency department 3 weeks prior and diagnosed with viral stomatitis. Culture of the lesions grew HSV I and the lesions had resolved by the time of this presentation. She had only been taking ibuprofen at home. The remainder of her medical history was unremarkable.
T 38.2°C; HR 130 bpm; RR 30/min; BP 98/60 mmHg; Oxygen saturation, 95% in room air
Weight 75th to 90th percentile
In general, she was crying and difficult to examine, holding her chest with both arms. She was not in significant respiratory distress. Her chest examination revealed no apparent bony tenderness over her sternum or ribs. She had decreased aeration at the left base with no wheezes or rales appreciated. Her eyes were slightly sunken and she had some crusty nasal discharge. Her lips and other mucous membranes were dry. The remainder of her physical examination was normal.
The girl’s complete blood count revealed 19 000 WBCs/mm3 (8% band forms, 81% segmented neutrophils, 11% lymphocytes). Hemoglobin was 12.8 g/dL and platelet count was 402 000/mm3. Electrolytes and liver function tests were normal.
COURSE OF ILLNESS
The girl was given a 40 mL/kg normal saline fluid bolus. She refused to drink and was therefore placed on maintenance intravenous fluids. A chest roentgenogram revealed the diagnosis (Figure 14-6).
FIGURE 14-6. Chest radiograph.
DISCUSSION CASE 14-5
As with adolescents, chest pain in the school-aged child is very rarely a life-threatening condition. Common causes of chest pain in this age group include asthma, pneumonia, and musculoskeletal (muscle strain, trauma, costochondritis). It is also quite common for chest pain to be deemed idiopathic. Less commonly, one may see a child with gastroesophageal reflux, pneumothorax, pneumomediastinum, or pleural effusion present with chest pain. As with the older child, the history and physical examination are crucial in guiding the appropriate work up.
Rarely, one will see a child with chest pain and cardiovascular disease. However, one must remember that this is the diagnosis that most families will be concerned about. Thus, it must be addressed, if even to reassure the family and child that it is not a concern. Certainly, children with palpitations, syncope, or chest pain with exertion should have a thorough evaluation for any cardiovascular disease. Finally, toddlers are always at risk for foreign body ingestion. While aspirated foreign bodies are not likely to give chest pain, esophageal foreign bodies may commonly present with chest pain.
The chest roentgenogram revealed round airspace opacities in the apical segment of the right lower lobe and the posterior basal segment of the left lower lobe (Figure 14-6). The diagnosis is pneumonia.
INCIDENCE AND EPIDEMIOLOGY
In children younger than 5 years of age, the yearly incidence of community-acquired pneumonia is 36-40/1000, and for 5-14 year olds, the incidence is 11-16/1000. In the United States, 1-4/1000 children are hospitalized every year with a lower respiratory tract infection. It is fairly difficult to develop a consensus definition of a case of pneumonia. Some define it based on an abnormal chest roentgenogram, while others require only the presence of clinical symptoms.
There are a large number of organisms that can cause community-acquired pneumonia in children. The most common causes include viruses (respiratory syncytial virus, influenza A and B, parainfluenzae, human metapneumovirus, adenovirus, and rhinovirus) Mycoplasma pneumoniae, Chlamydia species (C. trachomatis and C. pneumoniae) bacteria (Streptococcus pneumoniae, Mycobacterium tuberculosis, Staphylococcus aureus, Hae-mophilus influenzae type B, and nontypeable H. influenzae). Less common etiologies include other viruses (varicella, enteroviruses, cytomegalovirus, and Epstein-Barr virus), Chlamydia psittaci, less common bacteria (Streptococcus pyogenes, anaerobic mouth flora, Bordetella pertussis, Klebsiella pneumoniae, and Legionella), and fungi (Coccidioides immitis, Histo-plasma capsulatum, and Blastomyces dermatitidis).
Often, the difficulty is in differentiating a bacterial from a nonbacterial pneumonia. Classically, lobar infiltrates, cavitary lesions, and large pleural effusions suggest either bacterial or mycobacterial infections. Viral pneumonias typically present with diffuse radiographic involvement, but focal infiltrates can be seen. Laboratory data has been used in an attempt to differentiate viral from bacterial pneumonia, with C-reactive protein and white blood cell counts more significantly elevated in bacterial pneumonias. Ultimately, when attempting to determine the etiologic agent for pneumonia, one must consider the underlying immunologic function of the patient. Certainly, immunocompromised patients are susceptible to several other infectious etiologies that may be life-threatening.
One must also consider that some noninfectious processes may cause a similar clinical picture. These would include gastroesophageal reflux, chemical aspiration, asthma, hypersensitivity pneumonitis, and pulmonary hemosiderosis.
Generally, viral pneumonia will commence with upper respiratory tract infection symptoms, fever, rhinorrhea, and cough. Respiratory symptoms may be insidious. This is in contrast to most bacterial pneumonias where there is often an acute onset with fever, cough, and chest pain.
On physical examination, patients may have signs that are suggestive of consolidation (dullness to percussion, bronchial breath sounds, and egophony). This is more suggestive of a bacterial process. In contrast, patients with Mycoplasma or viral infections may have unimpressive physical examinations, but have very distinct infiltrates noted on their chest roentgenograms. Furthermore, patients with Mycoplasma may have a concurrent bullous myringitis.
Chest roentgenogram. As mentioned previously, the difficulty in diagnosing a pneumonia is differentiating a bacterial from a viral process. Lobar consolidation, cavitation, and large pleural effusions suggest a bacterial or mycobacterial process. Small, bilateral pleural effusions are present in approximately 20% of children with M. pneumoniae pneumonia. Pneumococcal pneumonia is the most common bacterial cause of lobar consolidation. However, approximately 10% of cases of Mycoplasma pneumonia present with lobar consolidation. Pneumatoceles are detected in two-thirds of children with pneumonia due to S. aureus (Figure 14-7). Viral pneumonias typically have a diffuse appearance that may be either interstitial or alveolar. Disease confined to the lower lobes, or the upper lobes in supine patients may suggest aspiration pneumonia.
FIGURE 14-7. Chest radiograph showing round lucencies within the right upper lobe indicating pneumatocele formation.
Chest computed tomography (CT) or ultrasound. For an uncomplicated pneumonia, chest CT or ultrasound is not necessary. However, chest CT is useful in cases of recurrent pneumonia or in recalcitrant cases. Furthermore, in the immunocom-promised patient, a chest CT may reveal subtle parenchymal disease. In children with a unilateral pleural effusion, chest CT and chest ultrasound can detect loculations and distinguish pleural effusions from anatomic abnormalities such as pulmonary lobe sequestration.
Sputum examination. Sputum culture may help identify the bacterial cause of pneumonia in adolescents but is not commonly predictive of the cause of pneumonia in younger children due to the difficulty in obtaining an adequate sputum sample. In addition, real-time PCR can be performed to detect the presence of viral products. PCR can also be used to detect M. pneumoniae. A nasopharyngeal wash or aspirate is the most sensitive specimen for these studies.
Bronchoscopy. As with chest CT, a bronchoscopy is not necessary in the uncomplicated pneumonia. However, a pneumonia that does not respond to appropriate antibiotic therapy may require bronchoscopy to obtain appropriate samples for culture. With this technique, a bronchoalveolar lavage is performed which can be analyzed for the causative organisms via gram stain, culture, and viral studies. Bronchoscopy is often indicated in immunocompromised patients who are at risk for opportunistic infections in addition to common bacterial and viral etiologies.
In the majority of cases, the causative organism is hypothesized but not verified. Therefore, therapy must be empiric. Table 14-6 summarizes the common organisms and recommended therapy by age group. In the newborn period, the most common organisms include group B streptococci, enteric Gram-negative bacteria (particularly Escherichia coli and Klebsiella species), and Listeria monocyto-genes. Thus, a combination of ampicillin and either gentamicin or cefotaxime is often used. There is no consensus as to when the newborn period is over, but after 3 weeks of age, the causative organisms tend to switch to Chlamydia trachomatis, viruses, Streptococcus pneumoniae, Bordetella pertussis, and S. aureus. Currently, the prevailing opinion is to treat these children (generally 3 week to 3 month age group) with amoxicillin, ampicillin, or cefotaxime.
TABLE 14-6. Common microbial causes and recommended empiric treatment for the hospitalized patient with community-acquired pneumonia.
From 3 months to approximately 5 years of age, the causative organisms tend to include viruses, S. pneumoniae, H. influenzae, M. pneumoniae, and M. tuberculosis. In a study of 3475 S. pneumoniae isolates by Whitney and colleagues, ampicillin was effective against 98% of isolates with intermediate sensitivity against penicillin while erythromycin and second-generation cephalosporin antibiotics were effective against only 65% of those same isolates. For these reasons, the Pediatric Infectious Disease Society (PIDS) and the Infectious Diseases Society of America (IDSA) clinical practice guidelines recommend either amoxicillin or ampicillin for the treatment of uncomplicated lobar pneumonia. Children allergic to aminopenicillins can receive either clindamycin or second- or third-generation cephalosporin-class antibiotics. Children with antecedent influenza infection are at higher risk for pneumonia due to S. aureus. For these children, an agent with activity against both S. pneumoniae and S. aureus, such as amoxicillin-clavulanate, clindamycin, or azithromycin, is preferred to treat pneumonia in the child with influenza. If methicillin-resistant staph aureus (MRSA) is suspected, clindamycin or vancomycin can be added to the regimen.
Finally, in the 5-15-year age group, Mycoplasma and Chlamydophila pneumoniae are more common than other etiologies including S. pneumoniae. Mycoplasma pneumonia has been shown in some studies to cause greater than 40% of community-acquired pneumonias in this age group. The PIDS/IDSA guidelines recommend ampicillin or amoxicillin as first-line therapy for suspected bacterial pneumonia. A macrolide can be used in addition to beta-lactam therapy if atypical bacteria, such as Mycoplsama, are significant considerations and instead of beta-lactam therapy if findings are characteristic of an atypical infection. Macrolides provide coverage for atypical bacteria but provide suboptimal coverage for pneumococcus. Treatment failure and breakthrough infections have occurred when macrolides, such as azithromycin, were used to treat serious pneumococcal infections. Certainly, in any age range, one should pursue the diagnosis of M. tuberculosis if it is at all clinically suspected.
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