Background: Bacillus Calmette-Guerin (BCG) vaccine is a live attenuated vaccine derived from a virulent strain of Mycobacterium bovis. BCG-related regional lymphadenitis, so-called BCGosis, is one of the common complications following BCG vaccination.

Objective: The purpose of this research was to study the bacteriology of BCGosis focusing on Mycobacterium bovis. The clinical presentations, investigations, treatments (both medical and surgical managements), and outcomes of BCGosis treatments were evaluated.

Materials and Methods: A retrospective review was performed of all BCGosis patients less than 1 year old who had failed to respond to medical treatment and had underwent surgical management for fluctuated inflamed BCGosis at the Division of Pediatric Surgery, Siriraj Hospital, from 2006 to 2016. Descriptive statistical analysis was performed.

Results: In total, 36 patients were reviewed. The most common location of BCGosis was the left axilla (58.3%). Almost all patients underwent excision, but there was only one patient underwent incision and drainage. AFB stains from the pathologic specimens and bacteriologic study were positive in 33.3% and 16.7% of cases, respectively. Mycobacterium bovis was isolated from the culture of 13 patients (36.1%). The conventional PCR test for Mycobacterium tuberculosis complex was performed in 33 patients, with a positive finding in only 24.2% of cases. No patients had surgical complications. Anti-tuberculosis drugs were given to 22 patients following the operation. The one-year recurrence-free time in this study was 93.8%.

Conclusion: Investigations for making a diagnosis of BCGosis have significant limitations. Further extensive investigations are needed for identification of the Mycobacterium bovis (BCG) stain from other strains of Mycobacterium tuberculosis complex. Surgical excision is the mainstay of treatment for BCGosis with a fluctuated inflamed mass with a low recurrence rate. The role of antituberculosis drugs is still unclear, but the author believes they have benefits in cases with a positive Mycobacterium bovis culture.

Keywords: BCG, Mycobacteria, Tuberculosis