Resident Rounds

January 2008

A 6-month-old previously healthy boy presented to the emergency department after three days of cough and fever to 101.5°F.

He was afebrile and nontoxic-appearing and was prescribed amoxicillin for bilateral otitis media. His mother reported continued fever to 102°F and cough over the next three days. In addition, she observed increased respiratory rate as well as “heavier breathing” over the 24 hours prior to admission. There was no audible wheezing or grunting, no cyanosis or nasal flaring by report prior to admission. The mother noted he had some decrease in oral intake and seemed to be sleeping more but otherwise was alert and interactive. There was no history of rhinorrhea, conjunctivitis, emesis, diarrhea or decreased urine output. There were no preceding or associated skin lesions or rashes.

With the continued symptoms noted above, the patient was brought to his primary care provider where he was noted to be febrile to 103°F with tachypnea and mild intercostal retractions. A chest radiograph was obtained that showed a left lower lobe infiltrate as well as a small pleural effusion. The child was given a dose of cefotaxime and transferred to the admitting hospital for further management.

The patient’s past medical history revealed no previous hospitalizations, surgeries or significant illnesses. He was born at term without complications. He had been treated for one episode of otitis media, with no history of pneumonia or sinus infections. His nutritional and developmental statuses were normal for age. He had only received one set of immunizations at two months to include the conjugated pneumococcal vaccine.

The infant lived with his healthy mother and father, and there were no other children in the home. There were no known ill contact exposures, although he attended daily childcare and was exposed to secondhand cigarette smoke intermittently. He had not traveled outside of his primary area of residence in Virginia and had no known animal exposures.

On arrival to the admitting hospital, the vital signs were: temperature 100.6°F, heart rate of 196 beats per minute, respiratory rate of 82 breaths per minute and blood pressure of 90/58 mm Hg. His oxygen saturations were 96% to 98% on room air. Overall, he was alert and interactive and easily consoled by his mother. He did appear to be in mild respiratory distress as evidenced by his tachypnea, in addition to mild intercostal retractions, intermittent grunting and nasal flaring. There was good air movement heard throughout the right lung fields and left upper fields. Decreased breath sounds and scattered crackles were heard in the left base. There was no conjunctivitis or ocular discharge, no rhinorrhea and oral exam was completely benign. There was no lymphadenopathy palpated, and abdominal exam showed no abnormal findings. His cardiac exam was significant for tachycardia with a normal rhythm, and no murmurs or gallops were auscultated. His distal pulses were easily felt, and the capillary refill time was one to two seconds. There was no noted skin trauma, lesions or rashes.

Initial laboratory results revealed a white blood cell count of 42.8 th/mm³ with 76% neutrophils, 4% bands and 18% lymphocytes. His hemoglobin was 11.6 g/dL, platelets were 752 th/mm³, and a complete metabolic panel, including liver function tests, was normal. Blood cultures and respiratory viral cultures were obtained on admission as well. Twenty-four hours after admission, the patient remains febrile with respiratory rates from 70 to 92 breaths per minute and continued grunting, nasal flaring and intermittent retractions. His oxygen saturations remain above 95% on room air, and a repeat chest radiograph shows worsening disease (Figure 1).

What further evaluation would you recommend? What organisms would you consider as the cause of this patient’s illness?

Answer

Continued signs of respiratory distress in this patient, although potentially due to the expected course of his illness, did raise the concern for the possibility of resistant organisms and/or progression of his pulmonary disease. Due to the lack of full immunizations, Haemophilus influenzae, an uncommon cause of pediatric pneumonia in this day of routine vaccination, was also considered possible.

Although this organism would have been expected to respond to ceftriaxone, methicillin-resistant Staphylococcus aureus might not. At this time, this must be at the top of the list of suspicious organisms and so therapy was changed to vancomycin.

Further imaging was recommended to evaluate for possible progression of the initial pleural effusion and signs indicating need for surgical intervention. Ultrasound was the preferred imaging modality, but due to technician constraints, a computed tomography scan of the chest was obtained that showed extensive loculations within the pleural effusion, consistent with a complicated effusion or empyema.

A surgical consult was obtained, and the patient was taken for video-assisted thoracoscopic surgery, where 100 mL of cloudy fluid was removed from the left pleural cavity, loculations were broken and a chest tube was placed. Pleural fluid studies showed a white blood cell count of 15,500 th/mm³; pH and LDH were not obtained.

Initial Gram’s stain of the pleural fluid showed gram-positive cocci in singles and pairs, and after 24 hours, the culture grew methicillin-resistant Staphylococcus aureus that was sensitive to clindamycin, trimethoprim/sulfamethoxazole and vancomycin. The patient completed one week of intravenous antibiotic therapy as an in-patient, and with improved clinical exam, normal temperatures and improving chest radiograph, the chest tube was removed. He was discharged home on oral antibiotics with plans to follow up after four days for evaluation and further antibiotic management.

Pediatric pneumonia

Pneumonia is a common infection of childhood, with estimates of 34 to 40 cases per 1,000 patients in children living in North America and Europe who are aged younger than 5 years. Incidence, morbidity and mortality are undoubtedly much higher in developing countries. The information discussed here applies primarily to community-acquired pneumonia of children aged older than 1 month in developed countries and is limited to a brief overview, given the scope of the subject and its related topics.

Epidemiology

A large number of both bacterial and viral organisms have been identified in children with pneumonia. Factors such as age, season, geographic location and ill contacts or other specific risk factors can often help guide the determination of the most likely etiologies.

Clinical signs and symptoms

Tachypnea, retractions and grunting in the presence of fever should make one suspect the diagnosis of lung parenchymal disease which may be confirmed by the presence of rales or evidence of fluid in the pleural cavity, ie, dullness or decreased breath sounds. Physical signs may be difficult to elicit in small infants. Radiographic studies may be useful in confirming the diagnosis and even suggest a bacterial as opposed to a viral etiology.

Additional studies such as a complete blood count, erythrocyte sedimentation rate and C-reactive protein may provide helpful information but rarely are specific enough for definitive diagnostic information. Blood cultures are specific but are positive in less than 10% of patients. Nasopharyngeal viral cultures can provide useful information although may not accurately represent lower respiratory tract organisms. Sputum cultures are not relied upon for diagnosis for similar reasons. Serologies may be misleading in patients with previous disease or concurrent illnesses and are not readily available for all potential pathogens. Pleural fluid samples and/or lung tissue provide the most sensitive material for culture and diagnostic purposes and should be obtained when possible in hospitalized or severely ill patients, those with effusions or patients who do not respond in the expected manner.

Complications

Complications of acute pneumonia include necrotizing infection, lung abscesses and in some cases bronchopleural fistula. Pleural effusions are present when fluid accumulates and when infection impedes the flow of pleural fluid from the visceral to the parietal pleura. Sometimes infection may spread to the pleural space and the fluid will be exudative with changes in lactate dehydrogenase, pH and glucose levels. An empyema conventionally refers to a complicated pleural effusion with opaque, purulent fluid. Pneumococcus continues to be the most common cause of empyema although staphylococcus also is a significant cause. Streptococcus is an uncommon cause and Hib has become rare since the advent of immunization against this organism.

Treatment

Treatment of acute pneumonia is optimally directed at an identified organism. More commonly, treatment must be targeted at the suspected or most likely cause. In the case of presumed viral etiologies, supportive therapy only is indicated.

In outpatients with presumed bacterial pneumonia, amoxicillin remains the recommended first-line agent. Despite the appearance of penicillin resistance in S. pneumoniae, high-dose amoxicillin or second-generation cephalosporins are often effective.

If factors are present that indicate need for admission, such as young age, underlying factors, inability to take fluids or oral medications, hypoxia, or toxic appearance, the recommended therapy is parenteral ceftriaxone or cefotaxime. Vancomycin is rarely if ever needed for treatment of pneumonia due to S. pneumoniae; however, it may be indicated in patients who are severely ill or for those in whom MRSA is suspected. In school-aged children, macrolides should be considered as first-line therapy due to the relative presence of M. pneumoniae as a causative agent; they should be considered in the treatment of hospitalized children aged 5 years and over as well. Uncomplicated community-acquired pneumonia is usually treated for a total of 10 to 14 days.

Treatment of complicated bacterial pneumonia typically consists of prolonged antibiotic therapy. With moderate to large effusions or to determine the etiology and obtain sensitivities, pleural fluid should be obtained and sent for Gram’s stain and culture, white blood cell count and differential, LDH, glucose, protein and pH. The method of obtaining this fluid is of great debate in the current pediatric and medical surgical literature, and a full comparison of the advantages and risks of each is beyond the scope of this discussion. Potential interventions include thoracentesis with or without chest tube placement and with or without instillation of intrapleural fibrinolytics, immediate video-assisted thoracoscopic surgery with placement of chest tube, or in severe or recurrent cases, open thoracotomy. Management decisions are best made by the primary pediatric team, in consultation with infectious disease specialists and pediatric surgeons when possible. Those patients with complicated pneumonia should be followed clinically and radiographically to ensure continued improvement and resolution or stability of signs and symptoms of disease.

For more information:

• Michael Rajnik, MD, is a Lieutenant Colonel in the U.S. Air Force. He is currently the pediatric infectious disease fellowship director and assistant professor of pediatrics at the F. Edward Herbert School of Medicine, Uniformed Services University of Health Sciences in Bethesda, Md.
• Dawn Muench, MD, is a Captain in the U.S. Air Force and Assistant Professor of Pediatrics at F. Edward Hebert School of Medicine, Uniformed Services University of the Health Sciences, in Bethesda, Md.
• McIntosh K. Community-acquired pneumonia in children. N Engl J Med. 2002;346:429-437.
• Long SS, Pickering LK, Prober CG. Principles and Practice of Pediatric Infectious Diseases. 2nd ed. Philadelphia: Churchill Livingstone; 2003.
• Bradley, J. Management of community-acquired pediatric pneumonia in an era of increasing antibiotic resistance and conjugate vaccines. Pediatr Infect Dis J. 2002;21:592-598.