Meningitis due to two serotypes of Escherichia coli. An infant who recovered

A newborn infant with hyaline membrane disease and aspiration pneumonia developed purulent meningitis on day 19, three days after discontinuation of ampicillin sodium and gentamicin sulfate therapy. Therapy with gentamicin, both systemically and intrathecally, for two weeks was ineffective. During this time each of four specimens of cerebrospinal fluid contained two serotypes of Escherichia coli, namely, O83:H4 and O75:H5. The antibiograms of the two strains were identical, both being susceptible to gentamicin and ampicillin. Treatment with ampicillin resulted in prompt disappearance of the infecting microorganisms and recovery from the infection. One of the strains (O75:H5) produced an antigen cross-reacting with the capsular antigen of Haemophilus influenzae type B; the other did not. The patient developed O antibodies in substantial titers against E coli O83 but not against E coli O75.