Resistance

The most common mechanism of isoniazid resistance is the mycobacteria's formation of mutations in cata-lase-peroxidase KatG, the enzyme that is responsible for activation of isoniazid. Another resistance mechanism is through a missense mutation related to the inhA gene involved in mycolic acid biosynthesis.

An active tuberculosis cavity may contain as many as 107 to 1010 microorganisms. The frequency of isoni-azid-resistant mutants in a susceptible mycobacterial population is about 1 bacillus in 106, and this organism is readily selected out if isoniazid is given as the sole agent. If a second drug having a similar drug resistance (1in 106) is combined with isoniazid, the odds that a bacillus is resistant to both drugs become 1 in 1012. Therefore, it is vital to combine at least two antitubercular agents to which the organism is susceptible.

Bacterial Vaginosis Facts

Bacterial Vaginosis Facts

This fact sheet is designed to provide you with information on Bacterial Vaginosis. Bacterial vaginosis is an abnormal vaginal condition that is characterized by vaginal discharge and results from an overgrowth of atypical bacteria in the vagina.

Get My Free Ebook


Post a comment