Trends and risk factors for drug-resistant tuberculosis among children in Sichuan, China: A 10-year retrospective analysis, 2013-2022

To investigate the status of the drug-resistant tuberculosis (DR-TB) among children in Sichuan, and to find out the risk factors and high-risk population related to drug resistance among children. The clinical data of tuberculosis patients ≤14 years old with culture-confirmed tuberculosis hospitalized in Chengdu Public Health Clinical Center from January 2013 through December 2022 were collected. Clinical data such as gender, age, ethnicity, history of anti-TB treatment, history of exposure to tuberculosis, nutritional status, and specific drug resistance of the children were collected and recorded. The drug resistance of children in different age groups (0-4 years old, 5-9 years old, 10-14 years old) and different periods (2013-2017 and 2018-2022) were grouped and compared. Logistic regression analysis was to analyze analysis of risk factors of drug resistance in children. A total of 438 children with culture-confirmed tuberculosis were screened. Among them, 26.19% (11/42) were 0 to 4 years old, 33.33% (22/66) were 5 to 9 years old, and 36.67% (121/330) were 10 to 14 years old among the resistant children. There was no statistically significant difference in the resistance rate among the 3 groups (P = .385). The proportions of DR-TB, monoresistant tuberculosis, polydrug-resistant tuberculosis were decreased during 2019 to 2022 compared with 2013 to 2017 (P < .0001). The resistance rates of drug resistant, monoresistant, polydrug-resistant, isoniazid-resistant, and rifampicin resistant during 2018 to 2022 were decreased compared with those from 2013 to 2017 (P < .05), but the multi-drug resistance rate was not decreased (P = .131, without statistical difference). The results of logistic regression analysis showed that male gender OR = 1.566 (95% CI 1.035-2.369), a history of antituberculosis therapy OR = 4.049 (95% CI 1.442-11.367), and pulmonary and extrapulmonary tuberculosis OR = 7.335 (95% CI 1.401-38.392) were risk factors for the development of drug resistance; but fever OR = 0.581 (95% CI 0.355-0.950) was Protective factor. The total drug resistance rate of children in Sichuan showed a downward trend, but the rate of multi-drug-resistant tuberculosis was still at a high level, and the form of drug resistance was still severe. Absence of fever, male, retreatment, and pulmonary concurrent with extrapulmonary tuberculosis are risk factors for DR-TB in children.

The epidemiological characteristics and profile of drug-resistant tuberculosis among children with tuberculosis in Sichuan, China, 2015-2018: A retrospective study

The aim of this study was to investigate the epidemiological characteristics and profile of drug-resistant tuberculosis (DR-TB) among children with TB in Sichuan province of China.From January 2015 to December 2018, microbiological culture-confirmed child TB cases (aged <15 years old) were enrolled retrospectively. Epidemiological and clinical information from these cases, and the drug susceptibility testing results of the isolates were collected and analyzed.Of 317 culture-confirmed child TB cases, 16.7% (53/317) were aged under 5 years old. 54.9% were Tibetans, and 31.9% had clear history of contact with TB patients. More than half (53.9%) were not vaccinated by Calmette-Guérin bacillus (BCG). Thirty percent (n = 95) were diagnosed as severe TB, and 92.4% (n = 293) were new cases. The ratio of severe TB in BCG vaccinated group was significant lower than that observed in unvaccinated group (P < .01). Significantly higher proportion of severe TB among Tibetans than Han child TB cases was observed in BCG unvaccinated group (P < .01). The overall rate of DR-TB in this study was 24.3% (77/317) and 17 multidrug-resistant tuberculosis (MDR-TB) cases were identified with rate of MDR-TB at 5.4% (17/317). No extensively drug-resistant case was found. Thirteen out of 17 MDR-TB cases (76.4%) were Tibetan children. The ratio of any resistance to 4 first-line drugs identified were: isoniazid (INH), 15.5%; rifampicin (RIF), 9.1%; ethambutol, 0.6% and streptomycin, 6.0%, respectively. More than half of MDR patterns were resistant to INH + RIF (9/17), followed by at least resistance to INH + RIF + streptomycin (n = 7).This was the first investigation on the epidemiological characteristics and profiles of DR-TB among child TB cases in Southwest of China. Our findings indicated a potentially high risk of TB infection to Tibetan children in the concentrated Tibetan communities of Sichuan.

Mycobacterial interspersed repetitive unit typing in Mycobacterium tuberculosis isolates from Sichuan province in China

BACKGROUND & OBJECTIVES

Emergence and spread of drug resistant Mycobacterium tuberculosis is a serious threat to tuberculosis (TB) control programme. Therefore, the objective of this study was to genotype drug-resistant M. tuberculosis strains isolated from patients in Sichuan, China, using Mycobacterial Interspersed Repetitive Units (MIRU) for epidemiological analysis.

METHODS

Drug-resistance testing of M. tuberculosis isolates from pulmonary TB patients was confirmed by proportion method. Twelve MIRU loci were analyzed on 80 drug-resistant and 9 susceptible isolates by polymerase chain reaction and agarose gel electrophoresis. Hunter-Gaston discriminatory index (HGI) values were determined for each 12 MIRU loci for the evaluation of their discrimination power.

RESULTS

Among 12 MIRU loci examined, polymorphic bands could be generated on 11 loci. Sixty five isolates had distinct MIRU patterns, while other 24 belonged to 8 clusters and resistant to at least one anti-TB drug tested. The association between the MIRU patterns and the mutation patterns of drug-resistance relevant target genes was not significant among the drug-resistant isolates.

INTERPRETATION & CONCLUSIONS

The results showed that with a satisfactory discrimination power exhibited, the 12 loci based MIRU typing could be a valuable tool for epidemiological studies in M. tuberculosis isolates from Sichuan.