The diagnostic bacteriologist, be that in the clinical or the veterinary field, plays a critical role in providing the laboratory based skills that underpin disease diagnosis. The role is one that can bring great challenges but also great satisfaction. As both a front-line diagnostic bacteriologist and a researcher focussed on improving diagnostic technologies, I have had personal experience for over 40 years of those challenges and those satisfactions. Along with a plethora of highly skilled colleagues, I have had the good fortune to be involved with a number of projects that have included the recognition and naming of two new genera (Avibacterium and Bibersteinia) and six new species, the development of novel approaches to the classic serotyping of two major respiratory pathogens (Avibacterium paragallinarum and Glaesserella parasuis), the replacement of a traditional classic serotyping with modern molecular methods (Actinobacillus pleuropneumoniae and Pasteurella multocida), and the acceptance by the CLSI of a proposed methodology for antimicrobial resistance testing for a key pig pathogen (Glaesserella parasuis). Over those 40 years, the issue that has not changed is the unique diversity that faces the veterinary bacteriologist. A diagnostic clinical bacteriologist deals with one host (the human) while a veterinary bacteriologist deals with multiple diverse hosts. This host diversity then results in diversity in both the pathogens and the normal flora that confronts the diagnostic bacteriologist. In my very early days, the problem was that the breakthrough diagnostic technology (API 20E strips) had a data-base focussed on clinical bacteria and thus failed to recognise key veterinary pathogens. Over 40 years later, the key break through diagnostic technology (MALDI-TOF MS) has a significant drawback for veterinary bacteriologist –a data-base that does not reflect the diversity of pathogens and normal flora seen in a typical veterinary laboratory. “Plus ça change, plus c'est la même chose”.