Trends in the discovery of new drugs for Mycobacterium tuberculosis therapy with a glance at resistance

Despite the low expensive and effective four-drug treatment regimen (isoniazid, rifampicin, pyrazinamide and ethambutol) was introduced 40 years ago, TB continues to cause considerable morbidity and mortality worldwide. In 2015, the WHO estimated a total of 10.4 million new tuberculosis (TB) cases worldwide. Currently, the increased number of multidrug-resistant (MDR-TB), extensively-drug resistant (XDR-TB) and in some recent reports, totally drug-resistant TB (TDR-TB) cases raises concerns about this disease. MDR-TB and XDR-TB have lower cure rates and higher mortality levels due to treatment problems. Novel drugs and regimens for all forms of TB have emerged in recent years. Moreover, scientific interest has recently increased in the field of host-directed therapies (HDTs) in order to identify new treatments for MDR-TB. In this review, we offer an update on the discovery of new drugs for TB therapy with a glance at molecular mechanisms leading to drug resistance in Mycobacterium tuberculosis.