Staphylococcus aureus -causes skin and tissue infections, suspected to be causing at least 25% of all hospital infections

Streptococcus -there are several types, causing sore throats, upper respiratory infections and pneumonia

Escherichia coli -causes urinary tract and wound infections, also problems after surgery

Proteus species -causes urinary tract infections

Salmonella species -causes food poisoning and typhoid

Shigella species -causes dysentry

Enterobacter species -causes respiratory tract infections and septicaemia

Pseudomonas aeruginosa -causes severe infections in burn victims, cancer patients, and cystic fibrosis

Hemophilus influenzae -causes ear and chest infections, especially in children

Bacteroides fragilis -ususally causes septicaemia following gastrointestinal surgey