How does drug resistance happen?

Q: How does drug resistance happen?

[fusion_builder_container hundred_percent="no" equal_height_columns="no" menu_anchor="" hide_on_mobile="small-visibility,medium-visibility,large-visibility" class="" id="" background_color="" background_image="" background_position="center center" background_repeat="no-repeat" fade="no" background_parallax="none" parallax_speed="0.3" video_mp4="" video_webm="" video_ogv="" video_url="" video_aspect_ratio="16:9" video_loop="yes" video_mute="yes" overlay_color="" video_preview_image="" border_size="" border_color="" border_style="solid" padding_top="" padding_bottom="" padding_left="" padding_right=""][fusion_builder_row][fusion_builder_column type="1_1" layout="1_1" background_position="left top" background_color="" border_size="" border_color="" border_style="solid" border_position="all" spacing="yes" background_image="" background_repeat="no-repeat" padding_top="" padding_right="" padding_bottom="" padding_left="" margin_top="0px" margin_bottom="0px" class="" id="" animation_type="" animation_speed="0.3" animation_direction="left" hide_on_mobile="small-visibility,medium-visibility,large-visibility" center_content="no" last="no" min_height="" hover_type="none" link=""][fusion_text columns="" column_min_width="" column_spacing="" rule_style="default" rule_size="" rule_color="" hide_pop_tinymce="" hide_on_mobile="small-visibility,medium-visibility,large-visibility" class="" id=""]Resistance to anti-TB drugs can occur when these drugs are misused or mismanaged. Examples include when patients do not complete their full course of treatment; when health care providers prescribe the wrong treatment, the wrong dose or length of time for taking the drugs; when the supply of drugs is not always available; or when the drugs are of poor quality.[/fusion_text][/fusion_builder_column][/fusion_builder_row][/fusion_builder_container]

Resistance to anti-TB drugs can occur when these drugs are misused or mismanaged. Examples include when patients do not complete their full course of treatment; when health care providers prescribe the wrong treatment, the wrong dose or length of time for taking the drugs; when the supply of drugs is not always available; or when the drugs are of poor quality.