The causative agent for AIDS is Human Immunodefeciency Virus or HIV.
Syphylis is a sexually transmitted disease caused by bacterium Triponema palladium.
Viral hepatitis is caused by different strains of hepatitis virus A, B and C
Gonorrhea is a sexually transmitted disease caused by Neisseria gonorrhooeae a gram negative bacteria.
Plague is caused by the gram negative bacteria Yersinia pestis.