In Chicago, IL, USA, in the late 1970s, hospitalisations for infective endocarditis due to Pseudomonas aeruginosa began to increase among people who inject drugs. 1 Shekar R Rice TW Zierdt CH Kallick CA Outbreak of endocarditis caused by Pseudomonas aeruginosa serotype O11 among pentazocine and tripelennamine abusers in Chicago. J Infect Dis. 1985; 151: 203-208 Crossref PubMed Scopus (45) Google Scholar Once a rare occurrence, by 1980, P aeruginosa was the most common cause of endocarditis among people who inject drugs at Cook County Hospital (Chicago). It became clear, however, that P aeruginosa did not affect all individuals injecting drugs equally. It predominantly affected those injecting pentazocine, an opioid, and tripelennamine, an antihistamine (a combination known as T's and blues), which unlike heroin, were not boiled before injecting. 2 Botsford KB Weinstein RA Nathan CR Kabins SA Selective survival in pentazocine and tripelennamine of Pseudomonas aeruginosa serotype O11 from drug addicts. J Infect Dis. 1985; 151: 209-216 Crossref PubMed Scopus (31) Google Scholar This drug combination allowed P aeruginosa serotype O11 strains to survive, while inhibiting the growth of other P aeruginosa serotypes and Staphylococcus aureus, the latter being the main pathogen associated with infections in people using heroin. 1 Shekar R Rice TW Zierdt CH Kallick CA Outbreak of endocarditis caused by Pseudomonas aeruginosa serotype O11 among pentazocine and tripelennamine abusers in Chicago. J Infect Dis. 1985; 151: 203-208 Crossref PubMed Scopus (45) Google Scholar , 2 Botsford KB Weinstein RA Nathan CR Kabins SA Selective survival in pentazocine and tripelennamine of Pseudomonas aeruginosa serotype O11 from drug addicts. J Infect Dis. 1985; 151: 209-216 Crossref PubMed Scopus (31) Google Scholar In other words, the specific drugs and the way they were injected modulated the risk for a particular infection, with T's and blues serving as a selective medium for P aeruginosa O11. Hydromorphone and the risk of infective endocarditis among people who inject drugs: a population-based, retrospective cohort studyAmong people who inject drugs, the risk of infective endocarditis is significantly higher for those exposed to controlled-release hydromorphone than to other opioids. This association might be mediated by the controlled-release mechanism and should be the subject of further investigation. Full-Text PDF