Abstract:

Objective: To explore transmission characteristics of multidrug-resistant pulmonary tuberculosis (MDR-PTB) in family. Methods: A total of 282 household contacts of 166 MDR-PTB patients (first generation cases) registered in Wuhan Pulmonary Hospital from July 2018 to June 2020 (MDR-PTB patients found in them were second generation cases) were enrolled. All the subjects were treated with tuberculin skin test (TST), chest X-ray, mycobacterium culture and phenotypic drug sensitivity test. Genotypes of strains from the first and second generation patients were tested by DTM-PCR and standard 24-loci MIRU-VNTR. The infection rate of Mycobacterium tuberculosis and the number of cases of MDR-PTB in close family contacts were calculated. The drug-resistant phenotype of first and second generation cases were compared, and the MIRU minimum spanning tree of the isolated strain was drawn. Results: Among 282 family contacts, the negative rate, general positive rate, moderate positive rate and strong positive rate of TST were 53.90% (n=152), 8.51% (n=24), 10.64% (n=30) and 26.95% (n=76), respectively, the infection rate of Mycobacterium tuberculosis was 37.59% (n=106). Of the 282 subjects, 9 (3.19%) had suspected symptoms, and 8 (2.92%) had abnormal chest films among 274 subjects who underwent chest X-ray. Among 106 subjects who had performed bacteriological examination of sputum Mycobacterium tuberculosis, 4 (3.77%) were positive in etiology, and all of them were second generation MDR-PTB, with a incidence rate of 1.42%. In the second generation cases, 3 cases had the same drug resistance phenotype as the indicator case, and 1 case was different. The 24 locus MIRU-VNTR genotyping of 6 strains from 3 families showed that the 24 loci of MIRU genotyping of 2 families were identical, and only 1 locus of 1 family was different. DTM-PCR genotyping showed that all 6 strains were Beijing strains. Conclusion: Close family contacts of MDR-PTB patients are at risk of infection. The incidence rate of second generation MDR-PTB in families is higher than that of the general population. Therefore, publicity, education, screening and follow-up should be coducted for close family contacts to reduce the spread of MDR-PTB within families.

Key words: Mycobacterium tuberculosis, Multidrug-resistant tuberculosis, Contact tracing, Family, Population surveillance