Detection of Mycobacterium in fine-needle aspiration biopsy specimens from children with tuberculous lymphadenitis

Abstract

Objective To improve the diagnosis of tuberculosis （ TB） by analyzing Mycobacterium infection in fine-needle aspiration biopsy specimens from children with tuberculous lymphadenitis .Methods Fine-needle aspiration biopsy was performed on 269 children with tuberculous lymphadenitis diagnosed by Shanghai Public Health Clinical Center from January 2011 to September 2013 .The needle aspiration biopsy specimens were processed for acid-fast bacillus （AFB） smear test, mycobacterial culture and Mycobacterium identification （ p-nitrobenzoic acid inhibition test ） .Results Cytological diagnosis of tuberculous lymphade-nitis was made for 269 patients.The positive results by AFB smear test were detected in 63.19% of 269 specimens （n=170） and 40.15%（n=108） specimens were positive in mycobacterial culture .The differ-ence between the two tests were significant （P<0.01）.The positive rate of Mycobacterium detected by using BACTEC MGIT 960 automated system and L？wenstein-Jensen culture method were 38 .66% （ n=104 ） and 28.99%（n=78）, respectively, showing the significant difference between two tests （P<0.05）.AFB smear test in combination with mycobacterial culture could precisely diagnose 70.63% of tuberculous lym-phadenitis in children.Of the 108 clinical isolates, 105 strains （97.2%） were Mycobacterium tuberculosis complex and the rest were non-tuberculous Mycobacterium strains （2.8%）.Conclusion The positive rate by AFB smear test was significantly increased in fine needle aspiration biopsy specimens after a series of treatments including sample digestion , centrifugation and precipitation , but the positive rate of mycobacterial culture was reduced .Diagnostic accuracy could be significantly improved by using BACTEC MGIT 960 sys-tem.Mycobacterium tuberculosis complex was the predominant pathogenic bacterium in children with tubercu-lous lymphadenitis . Key words: Children; Tuberculous lymphadenitis; Fine-needle aspiration; BACTEC MGIT 960 system; Lowenstein-Jensen culture; A acid-fast bacillus smear