Evaluation of Disk Potentiation Test (DPT) and Double Disk Synergy Test (DDST) for The Detection of Metallo-β-lactamases (MBLs) in Clinical Isolates of Bangladesh

ObjectiveIncreasing the emergence of Metallo-{beta}-lactamase (MBL) producing gram-negative Enterobacteriaceae and their dexterous horizontal transmission of the gene among other strains, demands rapid and accurate detection. This study was conducted to determine a suitable MBL detection method that could promptly identify the distribution of MBL-producing Gram-negative isolates at hospital settings in Bangladesh. MethodsA total of 103 gram-negative bacilli were identified from various clinical samples at a tertiary care hospital in Dhaka city. MBL producers were detected by two phenotypic methods; Disk Potentiation Test (DPT) and the Double Disk Synergy Test (DDST) based on {beta}-lactam chelator combinations where EDTA/SMA has been used as inhibitor and Imipenem, Ceftazidime as substrates. ResultsAll 103 isolates which were identified as Escherichia coli spp, Klebsiella spp, Pseudomonas spp, Acinetobacter spp, Proteus spp, Providencia spp were found to be multidrug-resistant in antibiogram test. All the mentioned isolates showed complete resistance (100%) to Imipenem, Meropenem, and Amoxiclav. The highest carbapenem-resistant etiological agents isolated were Acinetobacter spp 40 (38.8%) followed by Pseudomonas spp 27 (26.2%), Klebsiella spp 26 (25.2%), Escherichia coli 8(7.8%), Proteus spp 1(1%) and Providencia spp 1(1%). DPT method detected significantly (p=0.000009) higher number of MBL-producers (n=61, 59.2% & n=56, 54.4%) compared to the DDST method (n=43, 41.7%, n=38, 36.9% & n=15, 14.6%). ConclusionThis study depicts that DPT is a more sensitive method than DDST and could be recommended for identifying MBL-producing bacteria in Bangladeshi hospitals for the proper management of patients, and to reduce time constraints as well as treatment costs.