First Documented: 1872 Illness Caused: Pneumonia, Various Infections Antibiotic Resistance: Medium Virulence: Worrying Quick to mutate and adapt to counter different antibiotic treatments, Pseudomonas aeruginosa shows an innate ability to develop resistance to antibiotics. Described as ‘opportunistic’ because it primarily affects humans that are already critically ill, this bacteria can cause serious complications in the treatment of AIDS, cancer or cystic fibrosis patients. While it isn’t a massive threat to humanity currently, this bacteria will become an increasing threat over the next few years.