Recent Review on Subclass B1 Metallo-β-lactamases Inhibitors: Sword for Antimicrobial Resistance

Perspective of Secondary Metabolites in Respect of Multidrug Resistance (MDR): A Review

Aberrant and haphazard use of antibiotics has created the development of antimicrobial resistance which is a bizarre challenge for human civilization. This emerging crisis of antibiotic resistance for microbial pathogens is alarming all the nations posing a global threat to human health. It is difficult to treat bacterial infections as they develop resistance to all antimicrobial resistance. Currently used antibacterial agents inhibit a variety of essential metabolic pathways in bacteria, including macro-molecular synthesis (MMS) pathways (e.g. protein, DNA, RNA, cell wall) most often by targeting a specific enzyme or subcellular component e.g. DNA gyrase, RNA polymerase, ribosomes, transpeptidase. Despite the availability of diverse synthetic molecules, there are still many complications in managing progressive and severe antimicrobial resistance. Currently not even a single antimicrobial agent is available for which the microbes do not show resistance. Thus, the lack of efficient drug molecules for combating microbial resistance requires continuous research efforts to overcome the problem of multidrug-resistant bacteria. The phytochemicals from various plants have the potential to combat the microbial resistance produced by bacteria, fungi, protozoa and viruses without producing any side effects. This review is a concerted effort to identify some of the major active phytoconstituents from various medicinal plants which might have the potential to be used as an alternative and effective strategy to fight against microbial resistance and can promote research for the treatment of MDR.

Novel 1,2,3-Triazole-sulphadiazine-ZnO Hybrids as Potent Antimicrobial Agents against Carbapenem Resistant Bacteria

Bacterial pneumonia is considered one of the most virulent diseases with high morbidity and mortality rates, especially in hospitalized patients. Moreover, bacterial resistance increased over the last decades which limited the therapy options to carbapenem antibiotics. Hence, the metallo-β-lactamase-producing bacteria were deliberated as the most deadly and ferocious infectious agents. Sulphadiazine-ZnO hybrids biological activity was explored in vitro and in vivo against metallo-β-lactamases (MBLs) producing Klebsiella pneumoniae. Docking studies against NDM-1 and IMP-1 MBLs revealed the superior activity of the 3a compound in inhibiting both MBLs enzymes in a valid reliable docking approach. The MBLs inhibition enzyme assay revealed the remarkable sulphadiazine-ZnO hybrids inhibitory effect against NDM-1 and IMP-1 MBLs. The tested compounds inhibited the enzymes both competitively and noncompetitively. Compound 3b-ZnO showed the highest antibacterial activity against the tested metallo-β-lactamase producers with an inhibition zone (IZ) diameter reaching 43 mm and a minimum inhibitory concentration (MIC) reaching 2 µg/mL. Sulphadiazine-ZnO hybrids were tested for their in vitro cytotoxicity in a normal lung cell line (BEAS-2Bs cell line). Higher cell viability was observed with 3b-ZnO. Biodistribution of the sulphadiazine-ZnO hybrids in the lungs of uninfected rats revealed that both [124I]3a-ZnO and [124I]3b-ZnO hybrids remained detectable within the rats’ lungs after 24 h of endotracheal aerosolization. Moreover, the residence duration in the lungs of [124I]3b-ZnO (t1/2 4.91 h) was 85.3%. The histopathological investigations confirmed that compound 3b-ZnO has significant activity in controlling bacterial pneumonia infection in rats.

Draft genome sequence analysis of a high carbapenem-resistant Klebsiella quasipneumoniae subsp. quasipneumoniae strain isolated from an HIV-positive patient with pneumonia

OBJECTIVES

The rapid spread of Klebsiella spp. is recognised as a major threat to public health owing to a rise in the number both of healthcare- and community-acquired infections. Here we report the draft genome sequence of a high carbapenem-resistant Klebsiella quasipneumoniae subsp. quasipneumoniae strain (Cln185) isolated from a human immunodeficiency virus (HIV)-positive patient with pneumonia.

METHODS

Classical microbiological methods were applied to isolate and identify the strain. Genomic DNA was sequenced using an Illumina HiSeq platform and the reads were de novo assembled into contigs using CLC Genomics Workbench. The assembled contigs was annotated and whole-genome sequencing (WGS) was performed.

RESULTS

WGS analysis revealed that the genome comprised a circular chromosome of 5 406 774bp with a GC content of 57.73%. Three important antimicrobial resistance genes (bla_IMP-38, bla_OKP-B-6 and bla_DHA-1) were detected. In addition, genes conferring resistance to aminoglycosides, β-lactams, fluoroquinolones and tetracycline were also identified.

CONCLUSION

The draft genome sequence reported here will lay the foundation for future research on antimicrobial resistance and pathogenic mechanisms in K. quasipneumoniae subsp. quasipneumoniae and also will promote comparative analysis with genomic features among different sources of clinically important multidrug-resistant strains.

Strategies for discovery of new molecular targets for anti-infective drugs

Multidrug resistant bacterial pathogens as causative agents of infectious disease are a primary public health concern. Clinical efficacy of antimicrobial chemotherapy toward bacterial infection has been compromised in cases where causative agents are resistant to multiple structurally distinct antimicrobial agents. Modification of extant antimicrobial agents that exploit conventional bacterial targets have been developed since the advent of the antimicrobial era. This approach, while successful in certain cases, nonetheless suffers overall from the costs of development and rapid emergence of bacterial variants with confounding resistances to modified agents. Thus, additional strategies toward discovery of new molecular targets have been developed based on bioinformatics analyses and comparative genomics. These and other strategies meant to identify new molecular targets represent promising avenues for reducing emergence of bacterial infections. This short review considers these strategies for discovery of new molecular targets within bacterial pathogens.