Clostridium difficile
Anaerobic bacteria or facultative anaerobic bacteria.
anaerobic
aerobic bacteria use oxygen based respiration, anaerobic bacteria use either nonoxygen based respiration (e.g. nitrogen, sulfur) or fermentation.
anaerobic.
used for growth anaerobic bacteria
Salmonella bacteria are anaerobic.
what are the cause is anaerobic respiration in bacteria and fungi
Aerobic bacteria uses oxygen for cellular respiration and anaerobic bacteria doesn't require oxygen to survive. ˇ_ˇ 
Some methanogenic bacteria (which are anaerobic) do have flagella. You can read more in the related link
Anaerobic means without oxygen. Those are anaerobic bacteria.
Firstly, pathogenic is not the opposite of anaerobic. The vast majority of bacteria are non-pathogenic, but this doesn't mean they are anaerobic.
Anaerobic bacteria are bacteria that do not live or grow in the presence of oxygen. In humans, these bacteria are most commonly found in the gastrointestinal tract.