Case 2: An infant with fever

Chief complaint: Fever

History of present illness:
This is a two-month old boy born to a 33 year old G3P2 mother. At 34 weeks mother developed premature rupture of membranes. She had no fever but was placed on clindamycin. Baby developed fetal bradycardia and was delivered vaginally, vertex presentation, with forceps. Birth weight was 1.85 kg, and baby initially required bag-mask ventilation, with Apgar scores of 5 (one minute) and 8 (5 minutes). A 1.5 cm laceration was noted on the left inferior occiput that was closed with three sutures. Because of the premature rupture of membranes, a septic workup was done on baby, with negative results. He was given one dose of human immune globulin. He had a bilirubin of 12.5 and underwent a single phototherapy treatment on day # 3. He was discharged home on day #14 at a weight of 1.9 kg.
    At home, baby was breast fed and had no known problems until the day prior to admission when a fever was noted, rectal temperature 100.5 degrees F. On the day of admission mother thought he had a shrill cry and was difficult to console.  When he began to refuse breast feedings, mother took him to hospital.

Allergies: none
Medications: none
Past medical history: None except as given in HPI.
Social: Has two healthy siblings. There are no unusual exposures. A cat and a dog are kept in the house.

Physical examination:
Vital signs: Temperature 101.8 degrees F, Pulse 154, Respiratory rate 54, Blood pressure 110/47, Weight 3.8 kg.
General physical exam:  Baby was awake and appeared alert. There was a healed laceration in the left posterior scalp near the midline. Fontanelle was soft. Neck was supple. There were no oral lesions. Cardiac exam showed a normal rhythm with no murmur. Abdomen was soft.
Neurological exam:  Fundus examination was normal. Pupils were equal round and reactive to light. The left side of the face moved much less when the patient grimaced or cried. Deep tendon reflexes were symmetrical and of normal intensity. There was no clonus. Babinski responses were present bilaterally.

Initial laboratory studies:
Chest X ray:  normal
CBC:  hemoglobin 7.4, hematocrit 22.3, white blood cell count 13.6 with 45% segmented forms and 7% bands. Platelets were 366000.
Basic metabolic panel:  normal
Capillary blood gases: pH 7.45, pCO2 34, pO2 53, HCO3 24.
Liver function tests: normal except for alkaline phosphatase of 600.
Blood cultures were done, and were negative at 3 days.
Urine cultures were done, and were negative at 3 days.

Course of illness:
The patient was admitted to hospital with a diagnosis of infection, possible sepsis. Routine workup for infection was done. A had CT scan was done and was normal. A lumbar puncture was also performed. The fluid was cloudy, with a white blood cell count of 3900 per cu mm, and a differential showing 82% neutrophils, 6% mononuclear forms, 11% lymphocytes. Red blood cell count was 33, glucose was 9, and protein 421. Gram's stain was negative, and latex agglutination test also negative. The patient was immediately treated with ampicillin (200 mg IV Q 6 hours), cefotaxime (200 mg IV Q 8 hours), and vancomycin (58 mg IV Q 6 hours). He was given a blood transfusion. A brainstem auditory evoked response test was done, and no brainstem waves could be detected. His fever was gone by day 2 and he began feeding again.

1. What is the diagnosis?
2. Can you determine the most likely etiology?
3. The patient appears to have already had neurologic complications of this illness. What are they?
4. Is the patient's difficult birth and delivery to blame?

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