2^nd International Conference on
Worldwide Infectious Diseases

Biography:

Doctor is a strong advocate of advanced technology in clinical diagnosis of infectious diseases, she played a key role in the overall development of the Microbiology dept. at Nizam’s Institute of Medical Sciences and in catalyzing its emergence as an eminent referral laboratory. She made great strides in introducing automation in the laboratory as suited in a tertiary care hospital. Her special interest is in the development of simple, rapid and point of care assays for an early and cost effective diagnosis of infectious diseases. She is well known Internationally for the application of Dried Blood spot technology for surveillance of infectious pathogens. She was involved in several national and international collaborative projects of Public health importance and applied research, especially using the DBS and LAMP assay. Her research work on the LAMP assay for rapid molecular diagnosis of Infectious diseases such as HIV and Dengue, won 5 national awards.

 

Abstract:

Understanding genetic mechanisms of carbapenem resistance among  Gram-negative bacteria (GNB) could help tailor antibiotic therapy and lead to improved outcomes, particularly for critically ill patients. We developed a novel, low cost, bench side rapid molecular assay, V-CARB, based on the Loop mediated isothermal amplification (LAMP) technology that simultaneously identifies the 4 major carbapenemase genes: bla​_NDM, bla​_OXA-48, bla​_OXA-23 and bla​_VIM. The assay takes one hour and gives a clear visual readout. 188 clinical GNB isolates, were screened by the V-CARB assay for bla​_NDM, bla​_OXA-48,bla​_OXA-23and bla​_VIM genes and by the Kirby Bauer’s Disc diffusion susceptibility test (DDST). For isolates with mismatched results, the Carbapenem Inhibition assay (CIM) was undertaken.

41/188 (21.8%) isolates were positive for at least one gene by the V-CARB assay. Of these, 14 were detected as susceptible by DDST. 8/14 were true positives   and 6/14 were false positives. Further, 5 isolates detected as resistant by DDST were not identified by the V-CARB assay. Of these, 2 expressed unidentified carbapenemases, 1 was carbapenemase-independent and 2 were false negatives. With DDST as a gold standard, the LAMP assay had a sensitivity of 95%, negative predictive value of 98.61%, specificity of 95.95% and positive predictive value of 86.36%.

The different isolates tested included Acinetobacter (12), E. coli (108), Klebsiella (52) and Pseudomonas (16). The LAMP assay detected 9 NDM, 2 VIM, 16 OXA- 23 and 21 OXA-48 positive isolates. NDM was found across the species, except Pseudomonas. OXA-48 was more common among Klebsiella pneumoniae while OXA-23was found exclusively in Acinetobacter. VIM was detected in Pseudomonas and Klebsiella isolates. The V-CARB assay for carbapenemase genes developed by our team is a highly sensitive, specific, rapid and simple bench-side assay. The availability of the results in a clinically useful time will help clinicians select an appropriate antibiotic at the earliest.