Study patients
From 2017 June to 2018 Dec, we enrolled patients between 18 and 65 years diagnosed as MDR-TB confirmed by MTB MGIT 960 liquid culture and DST. Inclusive criteria were patients satisfied with the following conditions: patients were diagnosed as pulmonary MDR-TB confirmed by culture and DST at least resistant to isoniazid and rifampicin; patients had no previous history of anti-TB treatment or had previously administered only by first-line drugs or administered by second-line anti-TB drugs no more than one month; patients willing to join the study. Excluded criteria were as follows: patients had been administered by second-line anti-TB drugs more than one months; patients had poor compliance to any drugs within the regimens; had severe cardiovascular, liver, kidney, blood system or other serious diseases; coexisted with extrapulmonary tuberculosis; co-infected with HIV and other virus, taking immunosuppressive agents; pregnant or less than 18 years or older than 65 years.
Ethic Statement
The study was approved by The Ethics Committees of Shanghai Pulmonary Hospital, Tongji University School of Medicine, the approval number was k17-138. Individual participants were gave written informed consent before enrollment into the study. Adverse reaction was monitored by quality control team in the hospital in order to guarantee the most possibility of safety during the trial.
Study Design
Patients satisfied with included criteria were prospectively enrolled into the study, administered by the regimen including Capremycin(Cm), Levofloxacin(Lfx), Cycloserine(Cs), Protionamide(Pto), Pyrazinamide(PZA) and Pasiniazid(Pa)for six months with injectable Cm followed by 12 months of oral Lfx or Mfx, Cs, Pto, PZA and Pa. Levofloxacin was replaced by Moxifloxacin (Mfx) if patients cannot tolerate. The doses of drugs were administered according to the recommendation of Chinese guideline on treatment of MDR-TB and WHO guideline 2014(15). Cm was injectable administered by 750 mg/day, Lfx was orally 600 mg/day, Mfx 400 mg/day, Cs 250 mg every 12 h per day at initially 2 weeks and then 250 mg every 8 h per day, Pto1500 mg/day, Z 1500 mg/day, Pa was at 20 mg/kg/day (from 800 mg/day to 1200 mg/day taken orally after three meals). All included patients were followed up at outpatients department concerning treatment efficacy, side effects of drugs and safety monitoring. Sputum culture was tested once a month and Chest CT once three months. The evaluation of treatment efficacy was based on sputum culture conversion, treatment success rate and lesion absorption on Chest CT. Sputum culture negative conversion was considered when patients had negative results of two consecutive sputum cultures at least 30 days apart. Each patient was administered under directly observed therapy (DOT) throughout the treatment course.
Treatment outcomes was classified into as “cured”, ‘‘Completed treatment’’, ‘‘Treatment failure’’, ‘‘Defaulted’’ and ‘‘died’’ according to the WHO guideline(2).
BACTEC MGIT 960 Culture and DST
All enrolled patients was diagnosed and based on the sputum or BALF (Bronchoalveolar lavage fluid) culture positive by BACTEC Mycobacteria Growth Indicator Tube (MGIT) 960 system and DST, the procedure of BACTEC MGIT 960 culture (Difco/Becton Dickson, USA) and DST were followed by protocols of the kits (BD Biosciences, Sparks, Md.) The DST of drugs included Isoniazid, Rifampicin, Streptomycin,Ethambutol, Ofloxacin, Amikacin, Capremycin. Enrolled patients were tested by routine BACTEC 960 culture and DST by clinical laboratory at the beginning of chemotherapy and culture was performed during the course of the treatment.
Minimum Inhibitory Concentration (MIC) of the drugs that make up the regimen
Strains from patients were stored and available resuscitated were taken out and cultured, tested by MIC DST of drugs in the regimens including Cm, Lfx(Mfx), Cs, Pto, PZA and Pa. M. tuberculosis H37Rv (ATCC 27294) was used as a control strain. Clinical isolates and H37Rv were initially cultured in the BACTEC MGIT 960 system. Subsequently, 100 µL of each MGIT culture was inoculated onto Middlebrook 7H10 agar (Difco) supplemented with 10% ADC (5% bovine serum albumin BSA, 2% dextrose, 5% catalase) and incubated at 37 °C for 4–6 weeks. Colonies were scraped from 7H10 agar with visible bacterial growth, inoculated in Middlebrook 7H9 broth supplemented with 10% ADC and 0.05% Tween-80 (Sigma) and incubated at 37 °C for 3–4 weeks. Capreomycin (Cm Sigma), Cycloserine (Cs, Sigma), Protionamide (Pto, Suzhou Kaiyuan Minsheng Technology Co., Ltd., China) and pyrazinamide (PZA, Sigma) were dissolved in deionized water to make 10 mg/ml drug solutions. Levofloxacin (Lfx, Sigma), Pasiniazid (Pa, Chongqing Winbond Pharmaceutical Company, China) were dissolved in 0.1 mol/L NaOH and formulated into 10 mg/ml drug solution. All the drug solutions were filtered with a 0.22 µm sterile filter (Millpore Company, USA), and stored at -70℃ after separate packing. The final concentrations for each drug respectively diluted with Middlebrook 7H9 broth supplemented with 10% ADC and 0.05% Tween-80 were Cm 0.25 ~ 128 µg/ml, Cs 0.25 ~ 128 µg/ml, Pto 0.125 ~ 256 µg/ml, Pa 0.015 ~ 32 µg/ml, Lfx0.03 ~ 64 µg/ml and PZA 12.5 ~ 1600 µg/ml. An inoculum of M. tuberculosis from the log phase culture was transferred into sterile bottles containing 2.5 mL Middlebrook 7H9 broth and glass beads. The suspension was vortexed to break the clumps for 5–10 minutes, then left to sediment for 10–15 minutes. 2 mL supernatant was then transferred to sterile flat-bottomed glass test tubes, and the turbidity of the suspension was measured and adjusted to McFarland 1.0. The suspension was then diluted 1:10 for PZA MIC assay and 1:100 for MIC determination of other drugs with Middlebrook 7H9 broth, and then inoculated into the drug-containing 96-well plates. Meanwhile, 100%, 10%, 1% bacterial growth control well for each M. tuberculosis were set up. Plates were sealed and incubated at 37 °C for 14 days. The 96-well U-shaped plates were placed on an inverted magnifying glass to observe the white bacterial pellets in the bottom of each well and record the results that the presence of visible bacterial pellets is positive, but no visible bacterial pellet is negative. The MIC value was defined as the lowest drug concentration that inhibited growth of bacteria compared with the 10% (PZA) or 1% (other drugs) positive control. The MIC value of a strain to certain drug higher than (≥)the cut-off concentration is resistant to this drug. The cut off MIC values for all tested drugs were showed in Table 1.
Table 1
Drug concentration range (µg/mL) and the cut off concentration of MTB
| Concentration range(µg/mL) | Cut-off concentration (µg/mL) |
Capremycin | 2 ~ 128 | 8 |
Cycloserine | 0.5 ~ 128 | 32 |
Isoniazid | 0.5 ~ 16 | 0.2 |
p-aminohydroxyacid | 0.5 ~ 128 | 2 |
Pasiniazid | 0.015 ~ 32 | 1 |
Moxifloxacin | 0.06 ~ 32 | 0.5 |
Levofloxacin | 0.03 ~ 64 | 1 |
Protionamide | 0.5 ~ 256 | 8 |
Pyrazinamide | 12.5 ~ 1600 | 200 |
Treatment Efficacy Evaluation
The patients were examined by Chest CT imaging every three months and sputum culture once a month during the treatment period. The imaging was evaluated by two radiologists and two pulmonary specialists. “cure” was referred as patients completed treatment with consistently at least five negative culture results for the final 12 months of the treatment course and without evidence of treatment failure; ‘‘Completed treatment’’ was referred as patients completed the treatment according to the programme protocol but did not completed the requirement for bacteriological results; ‘‘Treatment failure’’ was referred as patients had sputum culture positive in the final 12 months of the treatment course or if any one of the final three cultures was positive; ‘‘died’’ was patients died from any reason during the course of anti-TB treatment; ‘‘Defaulted’’ was referred as patients whose TB treatment was interrupted for at least two consecutive months for any reason. Treatment success was defined as sum of cured and treatment completed and called as favorable outcome, unfavorable outcomes included “failure”, “default” and “death”.
Safety Assessment
Included patients were monitored by liver and lung function, blood routine testing at least once a months, hearing and vision testing once a month, followed at outpatients department of Tuberculosis by physicians once a moths or less if possible. Physicians can do with adverse reactions during follow up if happened.
Statistical analysis
Statistical analysis was used SPSS 18.0(IBM Corp, Armonk, NY, USA). Categorical variables such as treatment success rate, sputum conversion rate were analysed using X2 tests and Fisher’s exact tests, and continuous variables were analysed using independent t-tests and Mann-Whitney U-tests. P value < 0.05 was considered statistically significant. Multivariate analysis to determine the impact factors of treatment outcome was conducted with logistic regression model.