New drugs for tuberculosis are a major need for international public health. The results of clinical trials focussed on evaluation of fluoroquinolones for pulmonary tuberculosis are presented. From this work have emerged new methods to evaluate clinical trials data that have influenced methodology internationally. Isolates obtained in these studies have been the subject of molecular epidemiological typing methods. This led to the discovery ofpotential false matches in typing data bases. Later studies led to the demonstratiQP of the evolutionary pathways that individual strains take as lineages of M tuberculosis are transmitted in human communities. Studies demonstrating for the first time the fit~ess deficit associated with acquisition of resistance are presented and expanded to include the adaptation that occurs following the transmission of drug resistant strains between patients. Diagnostic methods have been studied, including not only studies of sensitivity and specificity but of the impact ofthese tests on management decisions. Lower respiratory tract infections are critically important 'and work is presented about the epidemiological spectrum. diagnosis of infection and antibiotic resistance. Diagnosis based on C-polysaccharide antigen led to studies on the biology of this organism and attempts to purify the enzymes involved in its synthesis led to the purification of pneumococcal enolase and important pathogenicity determinant. More recent work ·on the diagnosis of capsular serotype by molecular means is presented. Further experiments in evolution of drug resistance resulted in the demonstration of the unique evolutionary pathway to fluoroquinolones for the pneumococcus. The practical application ofmodem diagnosis is presented in studies ofadults and children in the UK and Africa. Further work to improve the diagnosis of bacteriological and parasitological infections including the results of clinical trials of treatment are presented that has allowed and extension of our knowledge ofthe clinical spectrum and epidemiology of these important infections.