Genetic weapons against bacterial resistance
Resistance to antibiotics is of major concern on a global scale. Low income countries face a particularly aggravated situation due to insanitary conditions combined with irrational and uncontrolled use of antimicrobials. There is therefore a high prevalence of antibiotic resistance in countries with poor resources, which is a constant threat to community health. The EU-led consortium of the ANTRES project chose to base their study in both urban and rural communities of Bolivia and Peru to monitor antibiotic use and consequent resistance levels. The project team at Ospedale le Scotte in the Tuscany region of Italy specifically researched into the development of molecular tools to investigate resistance mechanisms. The scientists probed for resistance genes to the most commonly used antibiotic classes, beta-lactamases, tetracyclines, sulphonamides, trimethoprims and phenicols,. In gram-negative bacteria, resistance to aminoglycosides is normally associated with integrons so the detection protocol used was designed to take this factor into account. Integron cassette arrays including primers for conserved integron regions were amplified using the polymerase chain reaction. Sometimes primers for the most common aminoglycoside resistance genes were incorporated. The uncovered resistance genes were then sequenced. The spread of antimicrobial resistance can be attributed to plasmid transfer during bacterial conjugation and the ability of the circular non-chromosomal DNA to replicate. The team adapted existing protocols to devise a methodology to characterise plasmid replicon types and to increase the understanding of the spread of resistance. The vast amount of data accumulated in the study was also used for a genotyping method, again developed from existing protocols, to investigate the clonal relationships between resistant Escherichia coli isolates. The study overall stands to provide data to use at community level right up to government bodies to improve both individual awareness and health policy making.
