Abstract:

Objective This study aimed to investigate the drug resistance status of patients with smear-negative while culture-positive pulmonary tuberculosis (PTB) in Guangdong province. Methods A total of 12323 newly diagnosed smear-negative PTB patients from 32 tuberculosis drug resistance surveillance sites in Guangdong province during January-December 2016 were collected as research subjects. After sputum culture, 1224 were culture positive, with culture positive rate of smear-negative of 9.9%. The results of strain identification tests indicated that 1177 cases (96.16%) were Mycobacterium tuberculosis complex, and 47 cases (3.84%) were nontuberculous mycobacteria (NTM). Then, drug sensitivity tests were performed on 1177 strains identified as Mycobacterium tuberculosis complex with 9 different anti-TB drugs, which were isoniazid (INH), streptomycin (Sm), rifampicin (RFP), ethambutol (EMB), kanamycin (Km), ofloxacin (Ofx), capriomycin (Cm), propionamide (Pto) and p-aminosalicylic acid (PAS). Results Totally, 12323 sputum isolates from newly diagnosed patients with smear-negative PTB were cultured, and the results showed that the total resistance rate was 29.57% (348/1177), including a multidrug resistance (MDR) rate of 2.38% (28/1177), extensive drug resistance (XDR) rate of 0.08% (1/1177), single drug resistance rate of 17.42% (205/1177), and a polyresistance rate of 9.77% (115/1177). We also found that the MDR rate (2.94%, 25/849) in men were significantly higher than those in women (0.91%, 3/328), with significant statistical differences (χ ²=4.19, P=0.040). There were 52 types of MDR spectrum, among which, INH+Sm resistant types were the most, accounting for 20.87% (24/1150, followed by Sm+Km resistant types, accounting for 9.57% (11/115). Conclusion Patients with smear-negative and culture-positive PTB in Guangdong province have a higher drug resistance rate. Monitoring and management should be strengthened to reduce the occurrence of drug-resistant tuberculosis.

Key words: Mycobacterium tuberculosis, Colony count, microbial, Drug resistance, bacterial, Microbial sensitivity tests