A Virulent Non-Encapsulated Haemophilus Influenzae.

Abstract

. The specific microbial virulence factors that allow nonencapsulated H influenzae to cause serious disease remain unknown, and to our knowledge, the ability of such organisms to cause invasive disease in an animal model has never before been demonstrated. Case HistoryA 30-month-old white boy was in his usual state of good health until 6 days before admission, when he developed a low-grade fever and abdominal pain. He was seen by his primary pediatrician, who noted right otitis media and prescribed amoxicillin, which was not taken because of vomiting. Three days before admission, he was seen in an emergency department, where he appeared lethargic and dehydrated with unresolved otitis media. There were no meningeal signs on examination. His peripheral leukocyte count was 21,000/mm3 with 580Zo neutrophils and 180Zo band forms. A blood sample was obtained for culture, the patient received intravenous rehydration and 50 mg/kg ceftriaxone intravenously, and was discharged home to resume amoxicillin administration.The child continued to be irritable and listless with fever to 39.20C over the ensuing 48-72 h but was able to take liquids and amoxicillin. He was carefully examined daily by his pediatrician who, on day 6 of symptoms, noted the development of passive