Ethambutol and isoniazid are antimicrobial agents used to treat multi-drug-resistant tuberculosis. The most commonly recognized toxic effect of these drugs is optic neuropathy, usually manifesting as a decrease in visual acuity, deficits in color vision and ceco central scotomas. Total visual loss is a rare complication that can be related to ethambutol and isoniazid toxicity. As precipitating ...

The influence of ethambutol on retinal function was studied by recording ganglion cell responses in isolated carp retinas superfused with a Ringer solution containing different concentrations of ethambutol (0 mg/liter, 10 mg/liter, 20 mg/liter, 30 mg/liter). The results indicate that ethambutol reversibly affects color opponency, without changing the sensitivity of the underlying receptor proce...

OBJECTIVES Ethambutol resistance has mostly been related to mutations in the embB gene. The objective of the present study was to characterize the embB gene in a collection of ethambutol-resistant and ethambutol-susceptible isolates of Mycobacterium tuberculosis complex (MTBC) from Barcelona, and to develop a DNA microarray for the rapid detection of embB mutations in our area. METHODS Fifty-...

OBJECTIVES To evaluate the inexpensive colorimetric nitrate reductase-based antibiotic susceptibility (CONRAS) assay for testing the susceptibility of Mycobacterium tuberculosis to streptomycin and ethambutol in liquid cultures, and to compare the CONRAS test with the manual mycobacteria growth indicator tube (MGIT) test, using the radiometric BACTEC 460TB method as reference. METHODS A total...

Contrast sensitivity was measured by means of Arden grating plates in 100 patients on medication for pulmonary tuberculosis. The scores were abnormal in 38.2% of the patients whose therapy included ethambutol for three months, and 36.7% of the patients on similar treatment for six months. In comparison with age matched groups of patients on a regimen where streptomycin replaced ethambutol a sta...

Ethambutol, a tuberculostatic drug, induces red-green colour vision defects in man and goldfish. The ethambutol-induced red-green colour vision defect in goldfish was argued to originate in the retina because after ethambutol application: (1) inhibitive interactions in red-green (double) opponent ganglion cells are lost [Van Dijk & Spekreijse, 1982 (Investigative Ophthalmology and Visual Scienc...

Seventy-four Mycobacterium tuberculosis clinical isolates from China were subjected to drug susceptibility testing using ethambutol, isoniazid, rifampin, and ofloxacin. The results revealed that the presence of embB mutations did not correlate with ethambutol resistance but was associated with multiple-drug resistance, especially resistance to both ethambutol and rifampin.

Only the dextro isomer of ethambutol inhibited mycobacterial spermidine synthase and spermidine biosynthesis. Inhibition of mycobacterial spermidine synthase appeared to be specific. Spermidine synthase from Mycobacterium fortuitum, which was resistant to ethambutol in vitro, required a higher concentration of ethambutol for its inhibition than the enzyme of susceptible Mycobacterium bovis.

The critical concentration (CC) for ethambutol testing on the Bactec MGIT 960 M. tuberculosis susceptibility testing has been questioned in recent publications. In this study, we correlate susceptibility results from the Bactec 460, MGIT 960 and embB gene sequencing to determine if the Bactec MGIT 960 adequately detects ethambutol resistance. We discovered discrepancies between the methods that...