Alarming emergence, molecular characterization, and outcome of blaNDM-1 in patients infected with multidrug-resistant Gram-negative bacilli in a tertiary care hospital

Emergence of OXA-833 in Proteus Species at a Tertiary Care Hospital in Dhaka, Bangladesh

CONTEXT

Proteus species are liable for multitude of infections and associated with resistance to routinely used antibiotics even to reserve drugs such as carbapenems.

AIMS

The aim of this study was to detect the presence of MBL producers, including blaOXA-833 gene in Proteus spp. along with their antibiotic resistance pattern.

SETTINGS AND DESIGN

This cross-sectional study was conducted in the Department of Microbiology of a tertiary care hospital of Bangladesh during July 2018 to June 2019.

SUBJECTS AND METHODS

Proteus spp. was isolated from a total of 500 samples. Antibiotic susceptibility was performed by disk-diffusion technique. Minimum inhibitory concentration (MIC) of imipenem was determined by agar dilution method. Carbapenemase producers were phenotypically detected by double disc synergy (DDS) test, combined disc (CD) assay, and modified Hodge test (MHT). Carbapenemase genes (blaKPC, blaVIM, blaIMP, blaNDM-1, blaOXA-23, blaOXA-48-like/blaOXA-833, and blaOXA-58) among imipenem-resistant Proteus spp. were detected by polymerase chain reaction (PCR). Sequencing was performed to differentiate OXA-833 from OXA-48-like gene by capillary method, and the nucleotide sequence of OXA-833 has been deposited to GenBank.

RESULTS

Ten (25%) imipenem-resistant isolates were detected during disk-diffusion technique, among them 60%, 70%, 50% carbapenemase producers were detected by DDS test, CD assay, MHT, respectively, and 70% by PCR. A significant increase in MIC was found between 8 and ≥128 μg/ml to imipenem. PCR revealed that 40% imipenem-resistant isolates were positive for blaNDM-1 and blaVIM followed by 20% for blaOXA-48-like/blaOXA-833 and blaOXA-23, respectively. Sequencing of blaOXA-48-like gene established the OXA-833 variant of class D carbapenemase encoding gene.

CONCLUSION

The results of this study showed the presence of high proportion of carbapenemase enzyme-producing Proteus spp. in Bangladesh. blaOXA-833 is emerging in Bangladesh.

Metallo-β-Lactamases: Structure, Function, Epidemiology, Treatment Options, and the Development Pipeline

Modern medicine is threatened by the global rise of antibiotic resistance, especially among Gram-negative bacteria. Metallo-β-lactamase (MBL) enzymes are a particular concern and are increasingly disseminated worldwide, though particularly in Asia. Many MBL producers have multiple further drug resistances, leaving few obvious treatment options. Nonetheless, and more encouragingly, MBLs may be less effective agents of carbapenem resistance in vivo, under zinc limitation, than in vitro Owing to their unique structure and function and their diversity, MBLs pose a particular challenge for drug development. They evade all recently licensed β-lactam-β-lactamase inhibitor combinations, although several stable agents and inhibitor combinations are at various stages in the development pipeline. These potential therapies, along with the epidemiology of producers and current treatment options, are the focus of this review.

Emergence of a multidrug-resistant ST 27 Escherichia coli co-harboring blaNDM-1, mcr-1, and fosA3 from a patient in China

In this study, we report a clinical isolate of a carbapenem-, colistin-, and fosfomycin-resistant Escherichia coli isolate DC-3737 co-harboring bla_NDM-1, mcr-1, and fosA3 from an inpatient in China. Antimicrobial susceptibility testing, polymerase chain reaction, multi-locus sequence typing, conjugation experiment, and Southern blot hybridization were performed on E. coli DC-3737 isolated from the wound. Plasmid analysis is presented and the locations of bla_NDM-1, mcr-1, fosA3, and other resistance genes were identified as well. E. coli DC-3737 was resistant to ampicillin, ceftriaxone, ceftazidime, ciprofloxacin, levofloxacin, gentamicin, tobramycin, trimethoprim-sulfamethoxazole, imipenem, meropenem, ertapenem, fosfomycin and colistin, and with intermediate susceptibility to amikacin. It was typed as sequence type 27. The isolate possessed bla_NDM-1, mcr-1, fosA3, bla_CTX-M-9, bla_TEM-1, aac (6')-Ib-cr and sul1 simultaneously. In addition, the mutations in quinolone resistance-determinant regions (QRDRs) such as Ser83Leu and Asp87Asn in gyrA, and Ser80Ile in parC were detected. Conjugation assays revealed that bla_NDM-1, fosA3, sul1, mcr-1, and bla_CTX-M-9 genes could successfully transfer their resistance phenotype to E. coli strain J53. Plasmid analysis and Southern hybridization showed that DC-3737 possessed Z-type self-transmissible plasmid bearing bla_NDM-1, fosA3, and sul1. Moreover, mcr-1, bla_CTX-M-9, and bla_TEM-1 were located on a ~60-kb IncFIB type self-transmissible plasmid. This is the first report of bla_NDM-1, mcr-1 and fosA3 co-harboring in E. coli in China. Moreover, it is also the first description of the co-harboring of bla_NDM and fosA3 in a single Z plasmid in Enterobacteriaceae species. The identification of E. coli DC-3737 co-harboring bla_NDM-1, mcr-1, and fosA3 in this study highlights the need to increase epidemiologic surveillance and the need for new classes of antibiotics to address multidrug-resistant bacteria.

An update on antimicrobial resistance and the role of newer antimicrobial agents for Pseudomonas aeruginosa

Infections due to Pseudomonas aeruginosa is a major health concern, especially hospital-acquired infections, in critically ill individuals. Antimicrobial resistance (AMR) increases the morbidity and mortality rates associated with pseudomonal infections. In this review, we aim to address two major aspects of P. aeruginosa. The first part of the review will focus on the burden of AMR and its prevailing mechanisms seen in India, while the second part will focus on the challenges and approaches in the management with special emphasis on the role of newer antimicrobial agents.