A 3-year old boy was brought to the emergency department (ED) with chief complaints of fever, vomiting, and cough. The boy’s mother described a two-day course of vomiting, which consisted of several episodes per day of nonbilious and nonbloody emesis. On the day of the ED visit, the vomiting had decreased to three episodes. During the past month, the child appeared more fatigued than usual and had a runny nose and an occasional nonproductive cough. The mother reported no sick contacts. There had been no loose stools, respiratory distress, or weight loss, and he was eating, drinking, and urinating normally.
That morning, the child was shivering and had a 103°F temperature, which prompted a visit to the primary-care provider. A WBC obtained at the pediatrician’s office measured 25,000/µL. The child was then referred to the ED.
Medical history
The boy had had three separate diagnoses in the past month, with one hospital admission. He was diagnosed with gastroenteritis four weeks before and admitted and discharged after a short stay. Two weeks later, the child was taken to his primary-care provider after complaining of a sore throat and being treated with penicillin G benzathine (Bicillin). Three days after this course of treatment, the patient was taken to the ED with a cough. He was diagnosed with croup, given a dose of ceftriaxone and dexamethasone, and sent home on oral steroids. After finishing the oral steroids, the patient again presented to his primary-care provider with an outbreak of herpetic whitlow, the most recent of occasional outbreaks first diagnosed at the age of 6 months. At the time of the current ED visit, he had been on acyclovir for 10 days.
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The boy’s mother reported no known drug allergies. The birth and family history were noncontributory, and no surgical history was identified. The child lived on a farm with both parents and one sibling in a nonsmoking household. There were no household pets. The child attended day care.
Review of systems
There were no complaints of upper respiratory congestion, hemoptysis, weight loss, night sweats, sore throat, cough, wheezing, or shortness of breath.
The mother doubted the possibility of foreign-body aspiration. The child did not complain of any chest discomfort, and no congenital cardiac anomalies had been identified. There was no stomach discomfort. The mother described formed, nonbloody, brown stools and clear yellow urine without blood, both of which were of sufficient quantity. There had been no change in urinary habits. The child’s skin was intact and without rashes. While no change in mentation or seizurelike activity was reported, he was reluctant to get out of bed.
Physical examination
The child was alert, oriented, quiet, and calm. Temperature was 98.9°F, heart rate 119 beats per minute, BP 99/56 mm Hg, respiration rate 22 breaths per minute, and oxygen saturation 100% on room air. Weight was 16.3 kg.
The physical examination was remarkable only for dullness, decreased fremitus, and decreased breath sounds heard over the lower lobe of the right lung. Resonance was noted throughout the remaining lung fields. Breath sounds were decreased in the right lower lobe. The skin exhibited good turgor and was intact and of normal temperature and color. The patient had no rash. Strength, sensation, and balance were intact, decreased only by lack of effort (the boy was reluctant to participate in testing). Deep tendon reflexes and cranial nerves were intact.
Laboratory results
A complete blood count, comprehensive metabolic panel, rapid flu determination, respiratory syncytial viral nasal washing, urinalysis, as well as urine and blood cultures were obtained.
Erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and coagulation studies were also ordered. The significant lab values were as follows: WBC 27,300/µL; granulocytes 8,100/µL; lymphocytes 10,000/µL; platelets 493,000/µL; carbon dioxide 17 mEq/L; glucose 53 mg/dL; blood urea nitrogen 19 mg/dL; ESR 52 mm/hr; prothrombin time 17.4 sec; international normalized ratio 1.4; CRP 7.87 mg/L; urinalysis positive for ketones; CD4/CD3 25/µL; immunoglobulin (Ig) E 49 IU/mL. Fecal WBC count, stool culture, urine culture, blood culture, acid-fast bacilli, anaerobes, fungal culture, monospot and rapid streptococcus A testing, immunoglobulin (Ig) M antibodies to mycoplasma, pneumonia IgG, IgA, and other CD4 combinations all were negative.
Studies
A chest x-ray taken in the ED revealed a 4.5-cm round area of consolidation in the lower lobe of the right lung. The left lung was clear, and the heart was of normal size. An abdominal CT scan with contrast was ordered one day after admission when the child complained of pain. The CT showed no abdominal anomalies but revealed a clearer view of the lung abscess (now more accurately measured as 4.5 × 3.3 cm).
Hospital course
Once diagnosed with right lung abscess, dehydration, and herpetic whitlow, the child was admitted to the pediatric unit and placed on IV ceftriaxone and clindamycin. He remained on acyclovir to counter exacerbation of the herpetic whitlow. An infectious disease specialist suggested staphylococcus, streptococcus, or (less likely) gram-negative rods as possible etiologies of the lung abscess.
Since the patient lived on a farm, Pasteurella multocida was included in the differential. Culture of the abscess revealed Streptococcus pneumoniae, resistant to penicillin and erythromycin. After the infectious disease consult, the antibiotics were changed to vancomycin and piperacillin/tazobactam, followed by CT-guided drainage of the subphrenic abscess with a pigtail drain and placement of a peripherally inserted central catheter (PICC). The patient continued on antibiotics plus morphine sulfate for pain. Throughout the hospital stay, he remained free of respiratory distress and required no oxygen. The patient had few febrile episodes. A repeat CT scan showed a significant decrease in the size of the abscess prior to discharge.
Discharge summary
The discharge diagnosis was S. pneumoniae right lung abscess (improved) and herpetic whitlow (improved). The patient was sent home in good condition after a nine-day stay. Discharge medications included ceftriaxone 1,250 mg daily for 14 days via PICC line and acyclovir 400 mg three times daily until the herpetic whitlow resolved. The parents were instructed to bring the patient for a follow-up CT scan in two weeks. Thoracic CT measurement of the lung abscess on discharge was 3.0 × 3.3 cm. The initial follow-up CT scan revealed a decrease in size to 2.2 × 2.2 cm. An additional follow-up CT revealed no evidence of cavitary lesion in the right lower lung field to suggest a lung abscess, and the remaining thorax remained within normal limits.
Discussion
Prior to the discovery of antibiotics, a diagnosis of lung abscess resulted in either death or debilitating disease. Today, the cure rate is 95%. Most lung abscesses are the end result of tissue necrosis following pneumonitis due to aspiration either of a foreign body or of mouth anaerobes from periodontal disease. Common anaerobes diagnosed in >89% of cases include Peptostreptococcus, Bacteroides, Fusobacterium, microaerophilic streptococcus, and Prevotella. Other organisms that cause lung abscess less frequently are Staphylococcus aureus, Klebsiella pneumoniae, Hemophilus influenzae, Actinomyces, Nocardia, gram-negative bacilli, Mycobacterium tuberculosis, Streptococcus pyogenes, and S. pneumoniae. Of course these organisms must be considered in the differential when evaluating the patient’s social and past medical history.
Nonbacterial pathogens, such as fungi and parasites, should also be considered. The immunocompetency of the patient should always be considered because of the complicated presentation and resistance to antibiotics in immunocompromised patients.
