Post-Vaccination Disseminated Bacillus Calmette Guerin Infection Among Children in Southern Iran

BACKGROUND: Disseminated bacillus calmette guerin (BCG) infection is a rare but life threatening complication of BCG vaccination. It has been mainly seen in severe immune deficiency. A precise and rapid diagnosis is crucial for prompt initiation of an aggressive anti-mycobacterial treatment. Polymerase chain reaction (PCR) is directly applicable to smear-positive clinical specimens, proven to be a rapid and specific diagnostic test. OBJECTIVES: The aim of this study was to investigate disseminated BCG infection among 34 children in southern Iran, mainly confirmed by PCR. PATIENTS AND METHODS: We included all the patients hospitalized with disseminated BCG infection at a referral teaching hospital in southern Iran between years 1990 and 2007. The clinical and laboratory data including the immunological workups were obtained through a review of the medical files. We recalled all pathology samples from pathology specimen banks and used an in-house PCR specific for Mycobacterium bovis BCG substrain to confirm the diagnosis. RESULTS: From the total of 34 children hospitalized with disseminated BCG infection, 21 were categorized as definite and 13 probable. Thirty-one patients (91%) were under two years of age and 41% were male. The most common clinical findings were fever in 31 (91.2%), axillary’s lymphadenopathy in 26 (76.5%), hepatosplenomegaly in 25 (73.5%), stunted growth in 21 (61.8%), and distant lymphadenopathy in 16 (47.1%). Polymerase Chain Reaction positivity rate was 100% (9 of 9) in bone marrow smear slides and 84.2% (16 of 19) for formalin-fixed and paraffin-embedded tissue specimens. Immunodeficiency state was detected in 50% and the overall mortality rate was 58.8% (20 of 34). CONCLUSIONS: Disseminated BCG infection should be considered in the differential diagnosis of infants and young children with fever, hepatosplenomegaly, lymphadenopathy, and history of BCG vaccination. The PCR method has a high positivity rate and can serve as a useful tool for the rapid and specific identification of M. bovis BCG substrain infection.