Bacterial DNA gyrase and topoisomerase IV are the major targets of quinolone antibiotic, and mutational alterations in quinolone resistance determining regions (QRDR) serve as major mechanism of resistance in most bacterial species, including P. aeruginosa. The present investigation was aimed to study the molecular mechanism of fluoroquinolone resistance among clinical P. aeruginosa isolated from Dhaka, Bangladesh, including alterations in target sites of the antimicrobial action. Laboratory collection of 53 P. aeruginosa were subjected to conventional cultural and biochemical characterization, followed by molecular identification using 16S rDNA sequencing. Susceptibility to ciprofloxacin and levofloxacin was tested by disc diffusion method followed by MIC assay. Resistant isolates were analyzed for mutation in their QRDR regions of gyrA and parC, and subjected to PCR detection of plasmid mediated quinolone resistance (PMQR) genes qnrA, qnrS and qnrB. Among the isolates, 28% were found to be resistant to both fluoroquinolones tested. All of the fluoroquinolone resistant isolates carried a single mutation in gyrA (Thr-83-Ile), while 20% carried a single parC mutation (Ser-87-Leu). Higher level of MIC was observed in isolates carrying alterations at both sites. None of the isolates harbored any PMQR genes investigated, suggesting that chromosomal mutations in QRDR regions to be the major contributing factor for quinolone resistance in P. aeruginosa under investigation.

Inappropriate antimicrobial use in food animal farming propels antimicrobial resistance (AMR) that affects all health domains. Colistin is a ‘Reserve’ antibiotic for human treatment to be conserved for multidrug-resistant pathogens; however, it is being used as an animal growth promoter in many developing countries. The evolution of mobilized colistin resistance (mcr) gene-mediated colistin resistance has been reported to be associated with rampant colistin use. This study investigated the current variants of the mcr gene in chicken gut contents in Bangladesh. A cross-sectional study was designed to assess the mcr-1 to mcr-5 genes in 80 fresh poultry droppings from commercial poultry farms and 40 poultry droppings from household farms. DNA was extracted from each poultry dropping using commercial kits (Qiagen GmbH, Hilden, Germany). Real-time quantitative polymerase chain reaction (RT-qPCR) was employed using the qTOWER3 thermal cycler (Analytik Jena GmbH, Jena, Germany) to analyze the mcr gene variants in the extracted DNA. This study observed that 47.5% (57/120) of the samples exhibited the presence of at least one mcr gene out of the five variants investigated. The individual detection rates of the mcr-1, mcr-2, mcr-3, mcr-4, and mcr-5 genes were 42.5% (51/120), 2.5% (3/120), 1.7% (2/120), 5% (6/120), and 9.2% (11/120), respectively. The co-carriage of two or more genes was found in over 10% (10/57) of the samples. The triple occurrence of mcr genes was identified in three samples with the combination of mcr-1+mcr-2+mcr-4, mcr-1+mcr-3+mcr-5, and mcr-1+mcr-4+mcr-5. Overall, a significantly higher number of mcr genes were identified in the commercial farm chicken droppings compared to the household chicken droppings (p = 0.007). The existence of mcr genes in poultry feces in Bangladesh emphasizes the importance of proper poultry waste disposal and good hygiene practices in poultry livestock and its value chain. The potential impact of environmental ARGs should be considered in national and global policy documents. An integrated and combined approach to the One Health concept should be applied in all domains to understand and control the environment’s role in the evolution and transmission of AMR.

Antibiotic-resistant Pseudomonas aeruginosa is a common nosocomial pathogen all over the world. We detected the presence of P. aeruginosa in 22% (53 out of 238) of the test samples collected from patients with infections including secondary wound infections, abscesses and urinary tract infections admitted to two academic hospitals in Bangladesh. Resistance to carbapenems (imipenem, and meropenem) was present among 30% (16 out of 53) of these clinical P. aeruginosa isolates, which is more than 2-fold higher compared to that of previous studies. Such a rapid increase in carbapenem resistance was mediated by metallo-β-lactamase (MBL). Expression of MBL was detected in 90% (14 out of 16) of these resistant isolates. Molecular analyses revealed that the carbapenem-resistant isolates carried at least one of the MBL variants, either bla- VIM or bla -NDM-1. All the bla- NDM-1 positives carried a 0.5 MDa plasmid. ERIC-PCR revealed the highly heterogeneous nature of the P. aeruginosa isolates indicating multiple sources of infection within the hospital. However, the majority of XDR isolates belonged to a single cluster of drug-resistant bacterial infections. These findings indicate that Metallo-β-lactamase (MBL) mediated resistance to carbapenem in P. aeruginosa poses a serious threat to the spread of infections among hospitalized patients.

Bacterial DNA gyrase and topoisomerase IV are the major targets of quinolone antibiotic, and mutational alterations in quinolone resistance determining regions (QRDR) serve as major mechanism of resistance in most bacterial species, including P. aeruginosa . The present investigation was aimed to study the molecular mechanism of fluoroquinolone resistance among clinical P. aeruginosa isolated from Dhaka, including alterations in target sites of the antimicrobial action. Laboratory collection of 53 P. aeruginosa were subjected to conventional cultural and biochemical characterization, followed by molecular identification using 16S rDNA sequencing. Susceptibility to ciprofloxacin and levofloxacin was tested by disc diffusion method followed by MIC assay. Resistant isolates were analyzed for mutation in their QRDR regions of gyrA and parC , and subjected to PCR detection of plasmid mediated quinolone resistance (PMQR) genes qnrA, qnrS and qnrB . Among the isolates, 28% were found to be resistant to both fluoroquinolones tested. All of the fluoroquinolone resistant isolates carried a single mutation in gyrA (Thr-83-Ile), while 20% carried a single parC mutation (Ser-87-Leu). Higher level of MIC was observed in isolates carrying alterations at both sites. None of the isolates harbored any PMQR genes investigated, suggesting that chromosomal mutations in QRDR regions to be the major contributing factor for quinolone resistance in P. aeruginosa under investigation.

Background and Objectives: Worldwide dissemination of Metallo-β-Lactamases (MBLs) has been reported as a major mechanism of resistance to carbapenems in clinical Gram-negative isolates, including Pseudomonas aeruginosa (P. aeruginosa). The present study aimed to investigate the occurrence of MBL variants in carbapenem resistant P. aeruginosa isolates from Dhaka, Bangladesh. Methods: Samples from ...