A gold nanoparticle colorimetric probe-based biosensor for rapid detection of VIM-2 and IMP-1 metallo-beta lactamase genes

Despite actions to reduce the prevalence of antibiotic resistance, antibiotic resistance remains a major threat in the treatment and control of infections. Therefore, the development of rapid diagnostic methods plays a significant role in the detection of antibiotic resistance genes and the management of hospital infections. This study aimed to design and develop a gold nanoparticle colorimetric probe-based biosensor was developed for faster and more accurate detection of VIM-2 and IMP-1 Metallo-Beta-Lactamases (MBLs) genes in different clinical samples. After identifying 248 clinical isolates of bacteria with standard biochemical methods and evaluation of antibiotic resistance and identifying MBL-producing strains, PCR method was carried out for detecting VIM-2 and IMP-1 genes as a gold standard. Synthesis of AuNPs were done by citrate reduction method and AuNP -IMP-1 biosensor was used for detecting IMP-1 gene, after functionalization of thiol modified oligonucleotides. AuNP biosensor and IMP-1 PCR were compared in terms of detection indices. Method PCR was defined as the gold standard. Bacteria examined, 87 isolates were resistant to carbapenems. Out of the 87 carbapenem-resistant isolates, 85 (34.2%) were phenotypically positive for MBLs. Also, 7 isolates had IMP-1 gene, but none of them carried VIM-2 gene. The AuNP biosensor had 100% sensitivity, specificity, PPV and NPV, respectively. The final detection limit of IMP-1 genomic DNA (LOD) by PCR and AuNP-IMP-1 biosensor technique was 0.1 fg/mu l (2.5 fg/25 reactions) and 0.001 fg/mu l (0.025 fg/25 reaction), respectively. According to the promising results of Diagnostic indices, AuNP biosensor is a more efficient and accurate method for direct and indirect detection of antibiotic resistance genes in clinical samples.