He spent a year at the University of Wisconsin–Madison before moving to the GlasgowInstitute of Virology in 1969, where he researched vaccinia, smallpox and other viruses. He was appointed Chair of Bacteriology at the University of Aberdeen in 1979, where he remained until his retirement in 2003. His research focused on improved bacteria typing, or "fingerprinting", methods, and led to new methods for the investigation of virulence and antibiotic resistance in a number of important pathogens including Staphylococcus aureus, Haemophilus influenzae, Neisseria meningitidis, and. He also wrote on the history of science and medicine such as the introduction of antiseptic surgery to Aberdeen by Alexander Ogston using a Lister 'steam spray producer'. He was dean of the medical school between 1987 and 1992. Pennington was also awarded a higher doctorate, i.e. DSc. From 2003-6 he was President of the Society for General Microbiology. He is a member of the Advisory Council for the Campaign for Science and Engineering.
Pennington Group enquiry
In late November 1996, an Escherichia coli outbreak in the town of Wishaw, central Scotland prompted the Scottish Office to establish an expert group, chaired by Pennington. The Pennington Group convened between December 1996 and March 1997. Another case of E. coli infection occurred in Tayside in January 1997 and the group was tasked with investigating the additional outbreak.
Subsequent public work
Following his chairmanship of the E. coli enquiry, Pennington has worked for the UK, Scottish and Welsh governments as an expert on microbiology and food safety, and has also appeared in British media as an expert. He was a member of the Scottish Food Advisory Committee, part of the Food Standards Agency, an agency he recommended the government create. He was a founder member of the World Food ProgrammeTechnical Advisory Group. He is the former Vice Chair of the Broadcasting Council for Scotland, which advises the BBC. He has criticised the UK and German governments for their handling of Bovine spongiform encephalopathy and the NHS for their handling of MRSA. He chaired a 2005 enquiry into a Welsh E. coli outbreak. The 2005 Outbreak of E. coli O157 in South Wales Public Inquiry report was published in March 2009. In 2003, Pennington published When Food Kills, a popular science book on the topic of BSE, E. coli and public food safety. He was appointed Commander of the Order of the British Empire in the 2013 Birthday Honours for services to microbiology and food hygiene.
Personal life
He married Carolyn Beattie in 1966 in Maidstone, Kent. They have two daughters.