A rapid molecular assay for the detection of antibiotic resistance determinants in causal agents of infective endocarditis

Aims: To develop and employ a PCR amplification system, directly from clini cal specimens, for the rapid molecular detection of common antimicrobial re sistance genes for streptococci, staphylococci and enterococci organisms ca using infective endocarditis (IE). Methods and Results: Eleven antibiotic resistance genes were targeted by PC R along with four identification-related loci. Blood culture and heart valv e material from staphylococcal endocarditis patients were directly examined for methicillin resistance. PCR conditions were optimized for the followin g antibiotic resistance loci: staphylococci (mecA, aacA-aphD), streptococci (PBP 1A, PBP 2B, gyrB, parE) and enterococci (vanA, vanB, vanC-1, vanC-2, aacA-aphD, aphA3). The presence of methicillin resistance was confirmed in one of the eight IE patients examined. Conclusions: This study presents a PCR amplification system for the detecti on of antibiotic resistance genes. Detection of such genes may indicate sus ceptibility of the causal agents of IE to commonly prescribed antimicrobial agents. Significance and Impact of the Study: Rapid detection of antibiotic resista nt organisms may reduce the use of inappropriate antibiotic agents or enabl e the use of the most appropriate combinations of antibiotics, other than t hose that would normally be prescribed empirically for IE. Such a method ma y be particularly valuable in cases of culture-negative endocarditis. Detec tion of antibiotic resistance genes by molecular-based techniques, namely P CR, will allow more directed antibiotic therapy and may also provide opport unities for earlier identification of resistant organisms.