Molecular epidemiology of an outbreak of fulminant hepatitis B

A nosocomial outbreak of hepatitis B occurred among the inpatients of a hem atology unit. Nine of the 11 infected patients died from fulminant hepatiti s. An investigation was conducted to identify the source of infection and t he route of transmission. Two clusters of nosocomial hepatitis B were ident ified. The hepatitis B virus (HBV) genome from serum samples of all case pa tients, of one HBsAg-positive patient with acute reactivation of the infect ion, and of eight acutely infected, unrelated cases was identified by PCR a mplification of viral DNA and was entirely sequenced. Transmission was prob ably associated with breaks in infection control practices, which occurred as single events from common sources or through a patient-to-patient route, likely the result of shared medications or supplies. Sequence analysis evi denced close homology among the strains from the case patients and that fro m the patient with reactivation, who was the likely source of infection. Mo lecular analysis of viral isolates evidenced an accumulation of mutations i n the core promoter/precore region, as well as several nucleotide substitut ions throughout the genome. The sequences of all patients were compared wit h published sequences from fulminant and nonfulminant HBV infections.