In vitro activity of ciprofloxacin, ofloxacin and levofloxacin against Mycobacterium tuberculosis

Biological In Vitro Evaluation of PIL Graft Conjugates: Cytotoxicity Characteristics

In vitro cytotoxicity of polymer-carriers, which in the side chains contain the cholinum ionic liquid units with chloride (Cl) or pharmaceutical anions dedicated for antituberculosis therapy, i.e., p-aminosalicylate (PAS) and clavulanate (CLV), was investigated. The carriers and drug conjugates were examined, in the concentration range of 3.125-100 μg/mL, against human bronchial epithelial cells (BEAS-2B) and adenocarcinomic human alveolar basal epithelial cells (A549) as an experimental model cancer cell line possibly coexisting in tuberculosis. The cytotoxicity was evaluated by MTT test and confluency index, as well as by the cytometric analyses, including Annexin-V FITC apoptosis assay. The polymer systems showed supporting activity towards the normal cells and no tumor progress, especially at the highest concentration (100 μg/mL). The analysis of cell death did not show meaningful changes in the case of the BEAS-2B, whereas in the A549 cell line, the cytostatic activity was observed, especially for the drug-free carriers, causing death in up to 80% of cells. This can be regulated by the polymer structure, including the content of cationic units, side-chain length and density, as well as the type and content of pharmaceutical anions. The results of MTT tests, confluency, as well as cytometric analyses, distinguished the polymer systems with Cl/PAS/CLV containing 26% of grafting degree and 43% of ionic units or 46% of grafting degree and 18% of ionic units as the optimal systems.

Intensified treatment with high dose rifampicin and levofloxacin compared to standard treatment for adult patients with tuberculous meningitis (TBM-IT): protocol for a randomized controlled trial

Background

Tuberculous meningitis is the most severe form of tuberculosis. Mortality for untreated tuberculous meningitis is 100%. Despite the introduction of antibiotic treatment for tuberculosis the mortality rate for tuberculous meningitis remains high; approximately 25% for HIV-negative and 67% for HIV positive patients with most deaths occurring within one month of starting therapy. The high mortality rate in tuberculous meningitis reflects the severity of the condition but also the poor antibacterial activity of current treatment regimes and relatively poor penetration of these drugs into the central nervous system. Improving the antitubercular activity in the central nervous system of current therapy may help improve outcomes. Increasing the dose of rifampicin, a key drug with known poor cerebrospinal fluid penetration may lead to higher drug levels at the site of infection and may improve survival. Of the second generation fluoroquinolones, levofloxacin may have the optimal pharmacological features including cerebrospinal fluid penetration, with a ratio of Area Under the Curve (AUC) in cerebrospinal fluid to AUC in plasma of >75% and strong bactericidal activity against Mycobacterium tuberculosis. We propose a randomized controlled trial to assess the efficacy of an intensified anti-tubercular treatment regimen in tuberculous meningitis patients, comparing current standard tuberculous meningitis treatment regimens with standard treatment intensified with high-dose rifampicin and additional levofloxacin.

Methods/Design

A randomized, double blind, placebo-controlled trial with two parallel arms, comparing standard Vietnamese national guideline treatment for tuberculous meningitis with standard treatment plus an increased dose of rifampicin (to 15 mg/kg/day total) and additional levofloxacin. The study will include 750 patients (375 per treatment group) including a minimum of 350 HIV-positive patients. The calculation assumes an overall mortality of 40% vs. 30% in the two arms, respectively (corresponding to a target hazard ratio of 0.7), a power of 80% and a two-sided significance level of 5%. Randomization ratio is 1:1. The primary endpoint is overall survival, i.e. time from randomization to death during a follow-up period of 9 months. Secondary endpoints are: neurological disability at 9 months, time to new neurological event or death, time to new or recurrent AIDS-defining illness or death (in HIV-positive patients only), severe adverse events, and rate of treatment interruption for adverse events.

Discussion

Currently very few options are available for the treatment of TBM and the mortality rate remains unacceptably high with severe disabilities seen in many of the survivors. This trial is based on the hypothesis that current anti-mycobacterial treatment schedules for TBM are not potent enough and that outcomes will be improved by increasing the CSF penetrating power of this regimen by optimising dosage and using additional drugs with better CSF penetration.

Trial registration

International Standard Randomised Controlled Trial Number ISRCTN61649292

Mutation characterization of gyrA and gyrB genes in levofloxacin-resistant Mycobacterium tuberculosis clinical isolates from Guangdong Province in China

OBJECTIVE

Fluoroquinolone (FQ)-resistant Mycobacterium tuberculosis (MTB) clinical isolates have emerged in many areas of the world. The aim of this study was to observe the molecular characterization of gyrA and gyrB genes in FQ-resistant MTB clinical isolates from Guangdong Province in China.

MATERIALS AND METHODS

A total of 62 MTB clinical strains were originally isolated from patients with pulmonary tuberculosis. The phenotype of susceptibility of each strain was determined by the absolute concentration method and the sequences of the QRDR in gyrA and gyrB genes were detected with DNA direct sequencing technique.

RESULTS

44 of 60 (73.3%) levofloxacin-resistant MTB clinical isolates, including 17 of 18 (94.4%) high-level resistant strains and 27 of 42 (64.3%) low-level resistant strains, had mutation in QRDR of gyrA gene. The mutation patterns involved six patterns of single codon mutation (H70R, A90V, S91A, D94G, D94A or D94N) and one pattern of double codons mutation (A90V with D94A). Of 60 levofloxacin-resistant MTB clinical isolates, only one (1.6%) mutated in gyrB gene (T511N).

CONCLUSIONS

These findings confirm that mutations of gyrA codons 90, 91 and 94 constitute the primary mechanism of FQ resistance in MTB. Furthermore, our findings indicate that the regional investigations are necessary for the comprehensive understanding of FQ resistance of MTB.

In vitro activity of a new isothiazoloquinolone, ACH-702, against Mycobacterium tuberculosis and other mycobacteria

In this work, we describe the activity of ACH-702 against clinical isolates of Mycobacterium tuberculosis and six different nontuberculous mycobacteria. The MIC(50) and MIC(90) of both susceptible and drug-resistant M. tuberculosis strains tested were 0.0625 and 0.125 microg/ml, respectively. The MIC(50) and MIC(90) values for Mycobacterium fortuitum isolates were 0.0625 microg/ml in both cases; Mycobacterium avium complex isolates showed MIC(50) and MIC(90) values of 0.25 and 4 microg/ml, respectively.