Challenges in identifying antibiotic resistance targets for point-of-care diagnostics in general practice

Mitsakakis, Konstantinos; Kaman, Wendy E; Elshout, Gijs; Specht, Mara; Hays, John P

The incidence of antibiotic resistance genes may vary per GP geographic location and in time, making it difficult for innovators to predict future trends in antibiotic resistance profiles. For example, β-lactam resistance in Haemophilus influenzae (associated with respiratory tract infections in primary care) has previously been associated with the carriage and expression of the transferable rob-1 β-lactamase genes [18] . However, there appear to be differences in the carriage of rob-1 between Canada, USA, Mexico, Scotland and Turkey [19] [20] [21] . That said, the most likely antibiotic resistance phenotype associated with a specific disease in a particular geographical location or community may already be known by the GP via his own empirical experience of recent treatment successes and failures. This empirical knowledge (along with national guidelines) may mean that antibiotic resistance testing is seen as unnecessary by some GPs. Additionally, if a POC diagnostic is implemented, which determines bacterial future science group www.futuremedicine.com identification only, the GP may already be empirically aware of the most likely antibiotic resistances associated with that particular bacterial pathogen. For example, the bacterium Moraxella catarrhalis is associated with upper respiratory tract infections such as otitis media in children and lower respiratory tract infections such as exacerbations of chronic obstructive pulmonary disease in adults [22] [23] [24] . This bacterial pathogen is associated with the carriage of a single unique β-lactamase enzyme, which can be present in one of two slightly different forms (Bro-1 and Bro-2) [25] . Further, epidemiological studies have shown that penicillin resistance and the carriage of bro genes approach 90% in clinical isolates, meaning that a POC diagnostic that detects the bro gene may not actually be useful (or seen as financially viable) to GPs, especially when a broad-spectrum alternative such as erythromycin is available for prescription. Of course, erythromycin resistance in clinical isolates of M. catarrhalis is known, but the incidence of such resistance is relatively low in most regions of the world [26] .