Gingival bleeding and halitosis is often the first sign of poor oral hygiene that may eventually lead to further periodontal problems, said Walter A. Bretz, DDS, PhD, Department of ...Germs to blame for bad breath... of the Journal of Microbiology that bad breath or halitosis is caused by certain types of bacteria that domina...ompare bacteria found on the tongues of those with halitosis and tho