Phenotypic and genotypic analysis of anti-tuberculosis drug resistance in Mycobacterium tuberculosis isolates in Myanmar.

BACKGROUND: Tuberculosis (TB) is one of the most serious health problems in Myanmar. Because TB drug resistance is associated with genetic mutation(s) relevant to responses to each drug, genotypic methods for detecting these mutations have been proposed to overcome the limitations of classic phenotypic drug susceptibility testing (DST). We explored the current estimates of drug-resistant TB and evaluated the usefulness of genotypic DST in Myanmar. METHODS: We determined the drug susceptibility of Mycobacterium tuberculosis isolated from sputum smear-positive patients with newly diagnosed pulmonary TB at two main TB centers in Myanmar during 2013 by using conventional phenotypic DST and the GenoType MTBDRplus assay (Hain Lifescience, Germany). Discrepant results were confirmed by sequencing the genes relevant to each type of resistance (rpoB for rifampicin; katG and inhA for isoniazid). RESULTS: Of 191 isolates, phenotypic DST showed that 27.7% (n=53) were resistant to at least one first-line drug and 20.9% (n=40) were resistant to two or more, including 18.3% (n=35) multidrug-resistant TB (MDR-TB) strains. Monoresistant strains accounted for 6.8% (n=13) of the samples. Genotypic assay of 189 isolates showed 17.5% (n=33) MDR-TB and 5.3% (n=10) isoniazid-monoresistant strains. Genotypic susceptibility results were 99.5% (n=188) concordant and agreed almost perfectly with phenotypic DST (kappa=0.99; 95% confidence interval 0.96-1.01). CONCLUSIONS: The results highlight the burden of TB drug resistance and prove the usefulness of the genotypic DST in Myanmar.

Linezolid for treatment of chronic extensively drug-resistant tuberculosis.

BACKGROUND: Linezolid has antimycobacterial activity in vitro and is increasingly used for patients with highly drug-resistant tuberculosis. METHODS: We enrolled 41 patients who had sputum-culture-positive extensively drug-resistant (XDR) tuberculosis and who had not had a response to any available chemotherapeutic option during the previous 6 months. Patients were randomly assigned to linezolid therapy that started immediately or after 2 months, at a dose of 600 mg per day, without a change in their background regimen. The primary end point was the time to sputum-culture conversion on solid medium, with data censored 4 months after study entry. After confirmed sputum-smear conversion or 4 months (whichever came first), patients underwent a second randomization to continued linezolid therapy at a dose of 600 mg per day or 300 mg per day for at least an additional 18 months, with careful toxicity monitoring. RESULTS: By 4 months, 15 of the 19 patients (79%) in the immediate-start group and 7 of the 20 (35%) in the delayed-start group had culture conversion (P=0.001). Most patients (34 of 39 [87%]) had a negative sputum culture within 6 months after linezolid had been added to their drug regimen. Of the 38 patients with exposure to linezolid, 31 (82%) had clinically significant adverse events that were possibly or probably related to linezolid, including 3 patients who discontinued therapy. Patients who received 300 mg per day after the second randomization had fewer adverse events than those who continued taking 600 mg per day. Thirteen patients completed therapy and have not had a relapse. Four cases of acquired resistance to linezolid have been observed. CONCLUSIONS: Linezolid is effective at achieving culture conversion among patients with treatment-refractory XDR pulmonary tuberculosis, but patients must be monitored carefully for adverse events. (Funded by the National Institute of Allergy and Infectious Diseases and the Ministry of Health and Welfare, South Korea; ClinicalTrials.gov number, NCT00727844.).

Development and evaluation of an automated stainer for acid-fast bacilli.

The current strategy for the control of tuberculosis (TB) relies on early diagnosis, and smear microscopy is an essential component of the laboratory diagnosis of TB in most countries with a high prevalence of the disease. However, even simple smear microscopy examination is far from satisfactory because staining results can vary among individual technicians. In an effort to minimize variations in manual staining procedures, we developed an automated stainer for AFB and evaluated its usefulness in comparison with manual staining. The key feature of our automated stainer is a heating apparatus required for fixation and carbol-fuchsin staining. After smear slides are placed into the machine, the entire staining process is fully automated, from fixation to final washing and drying. With the automated methods, five slides can be fixed and stained in 21 min at consistent high quality. Using sputum samples from 91 TB patients, the staining results of the automated stainer were compared blindly with those of manual staining. The concordance rate between the two methods was 94.5%. In addition, there was no significant difference in the rate of detection of AFB in the sputum samples. Although further optimization of the auto staining procedures is required, the results indicate that the automated AFB stainer developed in this study looks promising for use in clinical mycobacteriology laboratory in order to minimize personal variation during AFB staining.

Anthelmintic effect of amidental (Bay d 8815) against Ancylostoma duodenale infection.

A new anthelmintic, amidantel(Bay d 8815), an acetylated p-amino-phenyl-acetamidine was tried in 140 patients with Ancylostoma duodenale and other helminth infections. In the first trial, each 16 cases in 64 patients with A. duodenale were treated with 3.0, 6.0 and 9.0 or 10.0 mg/kg body weight of amidantel including placebo control. Another 76 patients infected with hookworms and other helminths were treated with 5.0, 6.0 and 8.0 mg/kg body weight of amidantel in the second trial. In order to assess the efficacy and safety of the drug, follow-up examination by repeated and replicated examinations over three consecutive days were performed at 14 to 16 days and 28 to 30 days after treatment, And complete laboratory studies including ECG were carried out before and one day after the medication. In the results, it was confirmed that amidantel is very effective against A. duodenale as well as Ascaris lumbricoides. With regard to dosage, a single dose of 6.0 mg/kg body weight of amidantel was found to be the most effective and well tolerated than the other dosages employed. In a single dose of 6.0 mg/kg body weight the cure rates were 93.8 and 96.6 per cent for A. duodenale infection and 90.9 and 93.1 per cent for ascariasis in the first and second trials respectivley. Relatively significant activity was also observed against Necator americanus at the dosages employed, however it was not superior to other drugs currently use. No significant activity was noted against Trichuris trichiura. Side effects including headache, nausea, dizziness and abdominal discomfort were usually mild and transient. No significant changes attributable to therapy were observed in hematology, blood biochemistry and urinalysis as well as ECG.

Effectiveness of anthelmintic drugs against Clonorchis sinensis infection of rabbits.

In order to find a highly efficient compound against Clonorchis infection, the anthelmintic activity of disophenol, Tremerad (SYD-230), dithiazanine iodide, dehydroemetine-late-release tablets(RO 1-9334/20), niridazole (Ambilhar), hexachlorophene (G-11), Hetol(1, 4-bis-trichloromethylbenzol) and Bilevon (niclofolan) was tested against Clonorchis sinensis experimentally infected rabbits. All drugs showed a progressive increase in efficacy as the dose rate. They were highly efficient against Clonorchis infection if sufficiently high, potentially toxic doses were given. The efficacy was evaluated by the number of detected worms with vital condition at autopsy after the treatment with above drugs. The high efficacy was observed at the following dose rates of each drugs, i.e. disophenol at a single dose of 30 mg/kg, Tremerad at the daily dose of 200 mg/kg for 10 consecutive days, dithiazanine iodide at the daily dose of 50 mg/kg for 6 consecutive days, dehydroemetine at the daily dose of 10 mg/kg for 10 consecutive days, hexachlorophene at the daily dose of 20 mg/kg for 10 to 15 consecutive days, Hetol at the daily doses from 50 to 100 mg/kg for 5 to 10 consecutive days, and Bilevon at a single dose of 8 mg/kg. Moderate effectiveness was shown in niridazole at the dose of 25 mg/kg for 10 days medication. The use of these anthelmintics for the clinical treatment of Clonorchis sinensis infection is discussed.