Doosoo Jeon

Extensive drug resistance acquired during treatment of multidrug-resistant tuberculosis.

BACKGROUND Increasing access to drugs for the treatment of multidrug-resistant (MDR) tuberculosis is crucial but could lead to increasing resistance to these same drugs. In 2000, the international Green Light Committee (GLC) initiative began to increase access while attempting to prevent acquired resistance. METHODS To assess the GLCs impact, we followed adults with pulmonary MDR tuberculosis from the start to the end of treatment with monthly sputum cultures, drug susceptibility testing, and genotyping. We compared the frequency and predictors of acquired resistance to second-line drugs (SLDs) in 9 countries that volunteered to participate, 5 countries that met GLC criteria, and 4 countries that did not apply to the GLC. RESULTS In total, 832 subjects were enrolled. Of those without baseline resistance to specific SLDs, 68 (8.9%) acquired extensively drug-resistant (XDR) tuberculosis, 79 (11.2%) acquired fluoroquinolone (FQ) resistance, and 56 (7.8%) acquired resistance to second-line injectable drugs (SLIs). The relative risk (95% confidence interval [CI]) of acquired resistance was lower at GLC-approved sites: 0.27 (.16-.47) for XDR tuberculosis, 0.28 (.17-.45) for FQ, and 0.15 (.06-.39) to 0.60 (.34-1.05) for 3 different SLIs. The risk increased as the number of potentially effective drugs decreased. Controlling for baseline drug resistance and differences between sites, the odds ratios (95% CIs) were 0.21 (.07-.62) for acquired XDR tuberculosis and 0.23 (.09-.59) for acquired FQ resistance. CONCLUSIONS Treatment of MDR tuberculosis involves substantial risk of acquired resistance to SLDs, increasing as baseline drug resistance increases. The risk was significantly lower in programs documented by the GLC to meet specific standards.

PET/CT imaging correlates with treatment outcome in patients with multidrug-resistant tuberculosis

PET/CT imaging in humans with TB correlates with drug response and final treatment outcomes. Visualizing Drug Responses in TB A pair of papers by Chen et al. and Coleman et al. investigate how changes in quantitative positron emission tomography/computed tomography (PET/CT) scans in both nonhuman primates and humans can be used as early surrogate markers of treatment efficacy in tuberculosis. The Coleman et al. study shows that treatment of Mtb-infected macaques with linezolid and the second-generation oxazolidinone AZD5847 resulted in a reduced bacterial load at necropsy and reduced FDG PET avidity and CT-quantified lung pathology. Similar PET/CT changes were seen in human patients infected with extensively drug-resistant Mtb and treated with linezolid. The companion study by Chen et al. corroborated this effect in a prospective analysis of patients with multidrug-resistant tuberculosis and demonstrated that early PET/CT changes predicted final treatment outcomes. Definitive clinical trials of new chemotherapies for treating tuberculosis (TB) require following subjects until at least 6 months after treatment discontinuation to assess for durable cure, making these trials expensive and lengthy. Surrogate endpoints relating to treatment failure and relapse are currently limited to sputum microbiology, which has limited sensitivity and specificity. We prospectively assessed radiographic changes using 2-deoxy-2-[18F]-fluoro-d-glucose (FDG) positron emission tomography/computed tomography (PET/CT) at 2 and 6 months (CT only) in a cohort of subjects with multidrug-resistant TB, who were treated with second-line TB therapy for 2 years and then followed for an additional 6 months. CT scans were read semiquantitatively by radiologists and were computationally evaluated using custom software to provide volumetric assessment of TB-associated abnormalities. CT scans at 6 months (but not 2 months) assessed by radiologist readers were predictive of outcomes, and changes in computed abnormal volumes were predictive of drug response at both time points. Quantitative changes in FDG uptake 2 months after starting treatment were associated with long-term outcomes. In this cohort, some radiologic markers were more sensitive than conventional sputum microbiology in distinguishing successful from unsuccessful treatment. These results support the potential of imaging scans as possible surrogate endpoints in clinical trials of new TB drug regimens. Larger cohorts confirming these results are needed.

Polymorphisms Associated with Resistance and Cross-Resistance to Aminoglycosides and Capreomycin in Mycobacterium tuberculosis Isolates from South Korean Patients with Drug-Resistant Tuberculosis

ABSTRACT The aminoglycosides streptomycin, amikacin, and kanamycin and the cyclic polypeptide capreomycin are all widely used in second-line therapy for patients who develop multidrug-resistant tuberculosis. We have characterized a set of 106 clinical isolates of Mycobacterium tuberculosis using phenotypic drug susceptibility testing (DST) to determine the extent of resistance to each agent and cross-resistance between agents. These results were compared with polymorphisms in the DNA sequences of ribosome-associated genes previously implicated in resistance and with the clinical outcomes of subjects from whom these isolates were obtained. Thirty-six (34%) of these isolates displayed resistance to one or more of these agents, and the majority of these (20 of 36) showed cross-resistance to one or more agents. Most (33 of 36) of the resistant isolates showed polymorphisms in the 16S ribosome components RpsL and rrs. Three resistant strains (3 of 36) were identified that had no known polymorphisms in ribosomal constituents. For kanamycin and streptomycin, molecular DST significantly outperformed phenotypic DST using the absolute concentration method for predicting 4-month sputum conversion (likelihood ratios of 4.0 and 2.0, respectively) and was equivalent to phenotypic DST using the National Committee for Clinical Laboratory Standards (NCCLS)-approved agar proportion method for estimating MIC (likelihood ratio, 4.0). These results offer insight into mechanisms of resistance and cross-resistance among these agents and suggest that the development of rapid molecular tests to distinguish polymorphisms would significantly enhance clinical utility of this important class of second-line antituberculosis drugs.

Efficacy and Safety of Metronidazole for Pulmonary Multidrug-Resistant Tuberculosis

ABSTRACT Pulmonary lesions from active tuberculosis patients are thought to contain persistent, nonreplicating bacilli that arise from hypoxic stress. Metronidazole, approved for anaerobic infections, has antituberculosis activity against anoxic bacilli in vitro and in some animal models and may target persistent, nonreplicating bacilli. In this double-blind, placebo-controlled trial, pulmonary multidrug-resistant tuberculosis subjects were randomly assigned to receive metronidazole (500 mg thrice daily) or placebo for 8 weeks in addition to an individualized background regimen. Outcomes were measured radiologically (change on high-resolution computed tomography [HRCT]), microbiologically (time to sputum smear and culture conversion), and clinically (status 6 months after stopping therapy). Enrollment was stopped early due to excessive peripheral neuropathies in the metronidazole arm. Among 35 randomized subjects, 31 (15 metronidazole, 16 placebo) were included in the modified intent-to-treat analysis. There were no significant differences by arm in improvement of HRCT lesions from baseline to 2 or 6 months. More subjects in the metronidazole arm converted their sputum smear (P = 0.04) and liquid culture (P = 0.04) to negative at 1 month, but these differences were lost by 2 months. Overall, 81% showed clinical success 6 months after stopping therapy, with no differences by arm. However, 8/16 (50%) of subjects in the metronidazole group and 2/17 (12%) of those in the placebo group developed peripheral neuropathy. Subjects who received metronidazole were 4.3-fold (95% confidence interval [CI], 1.1 to 17.1) more likely to develop peripheral neuropathies than subjects who received placebo. Metronidazole may have increased early sputum smear and culture conversion but was too neurotoxic to use over the longer term. Newer nitroimidazoles with both aerobic and anaerobic activity, now in clinical trials, may increase the sterilizing potency of future treatment regimens.

Multidrug-Resistant Tuberculosis Treatment Outcomes in Relation to Treatment and Initial Versus Acquired Second-Line Drug Resistance

BACKGROUND Resistance to second-line drugs develops during treatment of multidrug-resistant (MDR) tuberculosis, but the impact on treatment outcome has not been determined. METHODS Patients with MDR tuberculosis starting second-line drug treatment were enrolled in a prospective cohort study. Sputum cultures were analyzed at a central reference laboratory. We compared subjects with successful and poor treatment outcomes in terms of (1) initial and acquired resistance to fluoroquinolones and second-line injectable drugs (SLIs) and (2) treatment regimens. RESULTS Of 1244 patients with MDR tuberculosis, 973 (78.2%) had known outcomes and 232 (18.6%) were lost to follow-up. Among those with known outcomes, treatment succeeded in 85.8% with plain MDR tuberculosis, 69.7% with initial resistance to either a fluoroquinolone or an SLI, 37.5% with acquired resistance to a fluoroquinolone or SLI, 29.3% with initial and 13.0% with acquired extensively drug-resistant tuberculosis (P < .001 for trend). In contrast, among those with known outcomes, treatment success increased stepwise from 41.6% to 92.3% as the number of drugs proven effective increased from ≤1 to ≥5 (P < .001 for trend), while acquired drug resistance decreased from 12% to 16% range, depending on the drug, down to 0%-2% (P < .001 for trend). In multivariable analysis, the adjusted odds of treatment success decreased 0.62-fold (95% confidence interval, .56-.69) for each increment in drug resistance and increased 2.1-fold (1.40-3.18) for each additional effective drug, controlling for differences between programs and patients. Specific treatment, patient, and program variables were also associated with treatment outcome. CONCLUSIONS Increasing drug resistance was associated in a logical stepwise manner with poor treatment outcomes. Acquired resistance was worse than initial resistance to the same drugs. Increasing numbers of effective drugs, specific drugs, and specific program characteristics were associated with better outcomes and less acquired resistance.

Tuberculous Pleurisy: An Update

Tuberculous pleurisy is the most common form of extrapulmonary tuberculosis in Korea. Tuberculous pleurisy presents a diagnostic and therapeutic problem due to the limitations of traditional diagnostic tools. There have been many clinical research works during the past decade. Recent studies have provided new insight into the tuberculous pleurisy, which have a large impact on clinical practice. This review is a general overview of tuberculous pleurisy with a focus on recent findings on the diagnosis and management.

Low-dose heparin during extracorporeal membrane oxygenation treatment in adults

Dear Editor, Bleeding during extracorporeal membrane oxygenation (ECMO) is a potentially severe complication [1]. Excess anticoagulation may result in bleeding, unnecessary transfusions, and mortality [2]. Recent technological advances have reduced the amount of anticoagulation needed to prevent thrombosis [3]. We evaluated whether a lower target activated clotting time (ACT) during ECMO results in fewer hemorrhagic complications and a reduced need for blood products. The conventional (group C) and lower (group L) target groups comprised patients who received anticoagulation to maintain an ACT of 180–220 or 140–160 s, respectively, by continuous infusion of unfractionated heparin. Seventy-one patients were analyzed (Fig. 1 in the Electronic Supplementary Material, ESM). The indications for ECMO support were respiratory failure and cardiogenic shock (54 vs. 46 % patients, respectively). Forty-nine and 22 patients were treated with venoarterial and veno-venous ECMO, respectively; 69 % used vasopressors and 33.8 % underwent continuous renal replacement therapy. The preECMO clinical variables and coagulation profiles did not differ significantly between the two groups (Table 1 in the ESM). The mean activated partial thromboplastin time, ACT, and heparin dose during ECMO were higher in group C than L (Fig. 2 in the ESM). The incidences of major bleeding and bleeding-induced death were higher in group C than L (71.0 vs. 20.0 %, p\ 0.001; 22.6 vs. 2.5 %, p = 0.008; respectively) (Fig. 1a). The cannulation site was the most common bleeding site. The incidences of cannula-site and gastrointestinal bleeding were higher in group C than L (Table 2 in the ESM).

Imaging Findings of Primary Multidrug-Resistant Tuberculosis: A Comparison With Findings of Drug-Sensitive Tuberculosis

Objective: This study was designed to identify and describe thin-section computed tomographic (CT) findings of primary multidrug-resistant tuberculosis (MDR TB) as compared with the findings for drug-sensitive TB. Methods: Between October 2002 and December 2007, thin-section chest CT findings of 39 patients with primary MDR TB and 39 patients with drug-sensitive TB were retrospectively reviewed. The frequency and patterns of lung lesions (including centrilobular nodules, large nodules, consolidation, cavity, fibrotic bands, bronchiectasis, calcification, pleural effusion, lymphadenopathy, number of lobes affected by parenchymal lesions, and laterality) were compared. Statistical comparisons were performed with the use of the &khgr;2 and the Mann-Whitney U tests for univariate analysis, and a stepwise logistic regression method was used for multivariate analysis. Results: Based on univariate analysis, bilateral involvement (P < 0.001), segmental or lobar consolidation (P < 0.001), and cavities (P < 0.001) were more frequently seen in primary MDR TB patients. A stepwise logistic regression analysis demonstrated that bilateral involvement of parenchymal lesions (odds ratio, 4.7; 95% confidence interval, 1.4-15.6; P = 0.012) and multiple cavities (odds ratio, 1.7; 95% confidence interval, 1.2-2.5; P = 0.004) were significant CT findings associated with primary MDR TB. Conclusions: The presence of primary MDR TB as detected on a CT scan may help the use of appropriate therapy for infected patients before obtaining a definite diagnosis based on bacteriology.

The Utility of Preemptive Distal Perfusion Cannulation During Peripheral Venoarterial Extracorporeal Membrane Oxygenation Support

OBJECTIVES We compared the ischemia and rescue rates according to the strategy of distal cannulation. BACKGROUND Limb ischemia developing during percutaneous venoarterial (VA) extracorporeal membrane oxygenation (ECMO) is a potentially severe complication. Although appropriate use of a distal perfusion cannula can avoid ischemia, evidences about distal cannulation is still lacking. METHODS Patients who underwent peripheral VA ECMO between January 2010 and August 2015 were reviewed. We classified patients into 2 groups in terms of insertion timing with respect to the onset of ischemia. The preemptive strategy group underwent early insertion of a distal perfusion cannula at commencement of ECMO support. The rescue strategy group underwent delayed cannula insertion after onset of limb ischemia. RESULTS A total of 151 patients were included in the analysis. Forty-four patients formed the preemptive strategy group and 107 patients formed the rescue strategy group. In total, 10 of 151 (6.7%) patients developed significant limb ischemia, they all were the rescue strategy group (10/107, 9.3%). Of the 10 patients, 2 patients were rescued from limb ischemia after distal cannulation. Otherwise, ischemia was not rescued in the remaining eight patients. Of the latter 8, 3 patient required surgical interventions (2 fasciotomy and 1 below-the-knee amputation) and the other five died from disease aggravation prior to surgical intervention. CONCLUSIONS Preemptive distal perfusion cannulation is safe and effective when used to prevent lower limb ischemia in patients undergoing femoral cannulation to treat ECMO. However, delayed distal cannulation increases the extent of cannulation site bleeding, without improving the ischemia.

Impact of Implementation of an Automated Liquid Culture System on Diagnosis of Tuberculous Pleurisy.

This study was conducted to evaluate the impact of implementation of an automated liquid culture system on the diagnosis of tuberculous pleurisy in an HIV-uninfected patient population. We retrospectively compared the culture yield, time to positivity, and contamination rate of pleural effusion samples in the BACTEC Mycobacteria Growth Indicator Tube 960 (MGIT) and Ogawa media among patients with tuberculous pleurisy. Out of 104 effusion samples, 43 (41.3%) were culture positive on either the MGIT or the Ogawa media. The culture yield of MGIT was higher (40.4%, 42/104) than that of Ogawa media (18.3%, 19/104) (P<0.001). One of the samples was positive only on the Ogawa medium. The median time to positivity was faster in the MGIT (18 days, range 8-32 days) than in the Ogawa media (37 days, range 20-59 days) (P<0.001). No contamination or growth of nontuberculous mycobacterium was observed on either of the culture media. In conclusion, the automated liquid culture system could provide approximately twice as high yields and fast results in effusion culture, compared to solid media. Supplemental solid media may have a limited impact on maximizing sensitivity in effusion culture; however, further studies are required. Graphical Abstract