The patient was a 2-year-old female who had been taking amoxicillin for 8 days for an otitis media. She was brought in by her mother for a recurrence of fever, the development of cough, and increased work of breathing. The mother stated that four days ago, the child started to again spike fevers “over 100” and seemed to be having increased lethargy and decreased appetite. The patient’s vital signs revealed that she was febrile to 102F, tachycardic, and normotensive. On exam, the child was well appearing and in no acute distress. Auscultation to the lungs revealed decreased breath sounds throughout the right hemithorax and mild subcostal retractions. A two-view chest X-ray was obtained for further evaluation.
The patient’s X-ray showed near complete opacification of the right hemithorax with a small amount of mediastinal shift to the left. Additionally, there were small foci of gas at the right lung base and a larger collection of gas at the right lung apex with an air-fluid level.
In light of these findings, radiology recommended an ultrasound of the right lung to further characterize the disease process. The ultrasound demonstrated a large volume of loculated fluid in the right hemithorax and mobile gas within the pleural space.
With the findings from both the chest X-ray and the lung ultrasound, the definitive diagnosis of necrotizing pneumonia with empyema and bronchopulmonary fistula was made.
First identified in adults and later in children, necrotizing pneumonia is a rare, but serious complication of community acquired pneumonia (1). As the name suggests, the disease process involves destruction and necrosis of pulmonary tissue. It is thought that this significant tissue damage is caused by thrombosis of intrapulmonary vessels. This reduced blood flow not only leads to loss of pulmonary tissue, but also results in a reduction in local antibiotic concentration. The decrease in antibiotic penetrance allows for the active infection to flourish (2).
Since first being described in children in 1994, the rates of culture and pathologic proven necrotizing pneumonia are slowly increasing (1). Current reports indicate that necrotizing pneumonia may complicate around 4% of community acquired pneumonias (3) and up to 20% of pneumonias associated with empyema (4). It is thought that this increase is partly due to an increased awareness of the disease process, but also from changes in organisms and in antibiotic prescribing patterns (5). Of the reported cases of necrotizing pneumonia in literature, a majority have been caused by S. pneumoniae or S.aureus (1).
The clinical features of necrotizing pneumonia are nearly indistinguishable from those of community acquired pneumonia. Children often present with fever, cough, tachypnea, tachycardia, chest pain, and focal pulmonary findings on physical exam. Of the reported cases, a majority of children had been previously healthy without any significant co-morbid conditions (6). Often, children had been appropriately treated for community acquired pneumonia with outpatient antibiotic therapy, but re-presented with worsening or persistent symptoms (7).
There should be a high level of suspicion for necrotizing pneumonia for any child who remains unwell despite appropriate antibiotic treatment for community acquired pneumonia. Appropriate treatment most commonly being amoxicillin. Laboratory evaluation often shows an elevation in white blood cell count, elevation in C-reactive protein, hypoalbuminemia, and anemia (1). Additionally, patients who appear to be decompensating may demonstrate signs of septic shock such as a lactic acidosis and end-organ damage. As such, an infectious work-up is recommended including CBC, BMP, Lactic acid, VBG, CRP, and blood cultures.
Chest X-ray is often used as first-line for radiographic evaluation for necrotizing pneumonia and may reveal airspace opacity, gas foci, air-fluid levels, and mediastinal shift from mass effect. However, chest X-ray has poor sensitivity, particularly early in the disease course, as areas of necrosis are fluid filled and often have similar density to that of surrounding lung tissue. It is believed that for this reason, chest x-ray is only diagnostic in 27-41% of children with necrotizing pneumonia (1).
Given the poor performance of chest x-ray in the diagnosis of necrotizing pneumonia, contrast enhanced computed tomography (CT) has become the standard in diagnosing necrotizing pneumonia. With CT imaging of the chest, loss of vascularity, destruction of pulmonary tissue, and cavitary formation can be assessed. All of these findings are hallmark for necrotizing pneumonia (8).
Despite the increased sensitivity of CT, challenges exist in the pediatric population as patients are often unable to tolerate CT or are too sick to travel to radiology. For these reasons, pulmonary ultrasound has been studied in pneumonia and has been found to reliably detect lung consolidation (9). In a study in children with necrotizing pneumonia, doppler ultrasound was used to assess for lung hypoperfusion and was found to correlate well with CT scan results (10). For these reasons, lung ultrasound can be used to detect the consolidation found in community acquired pneumonia as well as the additional features of necrotizing pneumonia such as effusion, hypoechoic cavitary lesions, and decreased regional pulmonary perfusion. Challenges that exists with ultrasound are that it may not be available at all institutions and is highly dependent on operator skill level and comfort with pediatric patients.
Once the diagnosis of necrotizing pneumonia has been made, prompt treatment is warranted. Broad spectrum IV antibiotics should be initiated and selection of antibiotic should be based on local antibiogram and organism prevalence data. One suggested antibiotic regimen consists of ceftriaxone or cefotaxime plus clindamycin. At minimum, antibiotic selection should include coverage against gram positive organisms (11). As with all severe infections, antibiotics should be narrowed whenever possible on the basis of culture data.
Surgical intervention is not always warranted as invasive management can cause in an increase in bronchopulmonary fistula formation (12). However, if the initial workup reveals signs of mass effect, such as mediastinal shift, or evidence of loculated empyema, surgical consultation and debridement is required. Very often, video-assisted thoracoscopic surgery (VATS) is necessary for definitive management, but it has been suggested that chest tube drainage alone may suffice in cases of non-loculated parapneumonic effusions (1). Surgical intervention has the added benefit of being able to collect reliable culture data.
With the diagnosis of necrotizing pneumonia, the patient was started on vancomycin and ceftriaxone for broad antibiotic coverage. Pediatric surgery was consulted and determined that the patient would benefit from a VATS procedure. The patient was taken to the OR where a VATS was performed and two chest tubes were placed. Cultures were taken during the procedure and grew MRSA. The patient had an overall hospital stay of 8 days, during which the chest tubes were removed, and she was discharged with an extended course of clindamycin and infectious disease follow-up.
Faculty Reviewer: Dr. Jane Preotle
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