Effectiveness of combination therapy with ampicillin and gentamicin for a 2-month-old boy with group B streptococcal meningitis

摘要

Group B Streptococcus (GBS, or Streptococcus agalactiae) is among the most common causes of severe bacterial infections in early infancy. Combination therapy with ampicillin (AMP) plus gentamicin (GM) is recommended for such GBS infections, although this therapeutic approach has been based on relatively old in vitro and in vivo studies. Recently, a synergistic effect from this combination was found to involve ribosomal binding by GM allowed to enter bacterial cells by cell wall damaged from AMP. Here we report a 2-month-old boy with meningitis caused by GBS, against which AMP plus GM proved clinically effective. GBS isolated from his cerebrospinal fluid and blood belonged to capsular type III and sequence type17, and possessed hypervirulent GBS adhesin (HvgA); GBS isolated from maternal vaginal samples was the same type. In vitro determinations of time-kill kinetics for the patient's isolate showed enhancement of bactericidal activity by combining AMP with a small amount of GM. This case report provides clinical and laboratory evidence supporting effectiveness of combination therapy of AMP plus GM for severe GBS infection in early infancy.