[Associated factors for the infection of Beijing genotype Mycobacterium tuberculosis].
OBJECTIVE
to analyze the risk factors for the infection of Beijing genotype Mycobacterium tuberculosis (MTB) and the relationship to drug resistance and clinical symptoms.


METHODS
sputum samples were collected from patients with pulmonary tuberculosis who were admitted to the hospital during July, 2007 to March, 2008. The sputum was cultured with L-J method, and then the bacterial DNA was isolated and genotyped with VNTR-7 (variable-number tandem repeats, VNTR) and RD105 deletion method respectively. The association between different genotypes and risk factors was analyzed.


RESULTS
a hundred and sixteen clinical sputum isolates were obtained from 172 positive sputum cases. There were 112 isolates of MTB, and isolates of non-tuberculosis mycobacterium (NTM). Among the 97 isolates from Shanghai, Zhejiang and Jiangsu areas, Beijing genotype accounted for 86.6% (84/97), and non-Beijing genotype for 13.4% (13/97). The rates of MDR (multi-drug resistance), PDR (poly-drug resistance) and single drug resistance in Beijing genotype were not significantly higher than those in non-Beijing genotype. Among the risk factors, female gender, and CD(4)/CD(8)< 1 in patients with newly-treated tuberculosis, were associated with higher rate of Beijing genotype, chi(2) = 4.436, 4.494 and all P < 0.05, respectively. The Beijing genotype isolates were subdivided into 31 VNTR-7 types, and the distribution of quantity and resistance among different VNTR-7 genotypes was not even. A large number of MTB isolates (47.6%, 40/84) and drug resistant isolates (43.6%, 17/39) were among four VNTR-7 genotypes.


CONCLUSIONS
Beijing genotype is the most prevalent MTB in Shanghai, Zhejian and Jiangsu areas. Female gender and low CD(4)/CD(8) ratio in patients with newly-treated TB are risk factors for infecting Beijing genotype MTB, which may have no relationship with drug resistance and clinical symptoms.
Fan
Lin
L
Tongji University Affiliated by Shanghai Pulmonary Hospital, the Shanghai Key Laboratory of Tuberculosis, Shanghai 200433, China.
Gui
Xu-Wei
XW
Qin
Lian-Hua
LH
Wang
Jie
J
Hu
Zhong-Yi
ZY
Tang
Sheng-Jie
SJ
Xiao
He-Ping
HP
D002681:China / Q000453:epidemiology; D004269:DNA, Bacterial / Q000235:genetics; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000235:genetics* / Q000302:isolation & purification; D015995:Prevalence; D012307:Risk Factors; D013183:Sputum / Q000382:microbiology; D018088:Tuberculosis, Multidrug-Resistant / Q000235:genetics*; D014397:Tuberculosis, Pulmonary / Q000453:epidemiology / Q000235:genetics / Q000382:microbiology*
D004269:DNA, Bacterial