Antimicrobial compounds kill microorganisms or inhibit their growth, either in the host, outside on the skin (antiseptics), or in the environment (disinfectants). In the host they are named after the target symbiont, for example antibiotics, antifungals, and antiparasitics. It suffices to permanently stop an essential pathway in the symbiont to kill it. Broad spectrum antimicrobials usually target a conserved pathway like protein synthesis or cell wall construction, in order to affect a whole taxonomic group (Arenz & Wilson 2016, Barry et al. 2007, Green 2002).
Resistance of microorganisms (bacteria, viruses, parasites) to antimicrobials is one of the most important public health problems. Many mechanisms exist, and they are either acquired by mutation, by horizontal gene transfer, or are already intrinsic to the organism. The main mechanisms are modification of the antimicrobial, or its removal from the place of action, modification of its binding partner in the affected pathway, or usage of a back-up pathway. Participation of the organism in a consortium (like in biofilms) enables additional resistance mechanisms (Aminov & Mackie 2007, Peterson & Kaur 2018, van Acker et al. 2014, van Acker & Coenye 2016).
The events described here are specific to Mtb infection.