Identification and characterization of colistin-resistant E. coli and K. pneumoniae isolated from Lower Himalayan Region of India

Unveiling the ecological landscape of bacterial β-lactam resistance in Delhi-national capital region, India: An emerging health concern

Inappropriate antibiotic use not only amplifies the threat of antimicrobial resistance (AMR), moreover exacerbates the spread of resistant bacterial strains and genes in the environment, underscoring the critical need for effective research and interventions. Our aim is to assess the prevalence and resistance characteristics of β-lactam resistant bacteria (BLRB) and β-lactamase resistant bacterial genes (BLRBGs) under various environmental conditions within Delhi NCR, India. Using a culture-dependent method, we isolated 130 BLRB from 75 different environmental samples, including lakes, ponds, the Yamuna River, agricultural soil, aquatic weeds, drains, dumping yards, STPs, and gaushalas. Tests for antibiotic susceptibility were conducted in addition to phenotypic and genotypic identification of BLs and integron genes. The water and sediment samples recorded an average bacterial abundance of 3.6 × 106 CFU/mL and an average ampicillin-resistant bacterial count of 2.2 × 106 CFU/mL, which can be considered a potent reservoir of BLRB and BLRBGs. The majority of the BLRB discovered are opportunistic pathogens from the Bacillus, Aeromonas, Pseudomonas, Enterobacter, Escherichia, and Klebsiella genera, with Multiple Antibiotic Resistance (MAR) index ≥0.2 against a wide variety of β-lactams and β-lactamase (BLs) inhibitor combinations. The antibiotic resistance pattern was similar in the case of bacteria isolated from STPs. Meanwhile, bacteria isolated from other sources were diverse in their antibiotic resistance profile. Interestingly, we discovered that 10 isolates of various origins produce both Extended Spectrum BLs and Metallo BLs, as well as found harboring blaTEM, blaCTX, blaOXA, blaSHV, int-1, and int-3 genes. Enterobacter cloacae (S50/A), a common nosocomial pathogen isolated from Yamuna River sediment samples at Nizamuddin point, possesses three BLRBGs (blaTEM, blaCTX, and blaOXA) and a MAR index of 1.0, which is a major cause for concern. Therefore, identifying the source, origin and dissemination of BLRB and BLRGs in the environment is of the utmost importance for designing effective mitigation approaches to reduce a load of antimicrobial resistance factors in the environmental settings.

Antimicrobial resistance profiles of Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumoniae strains isolated from broiler chickens

Globally, the spread of multidrug-resistant Pseudomonas aeruginosa, Escherichia coli, and Klebsiella pneumoniae from food to humans poses a severe threat to public health. The aim of this study was to assess the co-occurrence of colistin and β-lactamase resistance genes in E. coli, K. pneumoniae, and P. aeruginosa strains isolated from faeces of abattoir broiler chickens. The E. coli, P. aeruginosa and K. pneumoniae isolates were successfully detected from faecal samples by polymerase chain reaction (PCR) at infection rates of 60.7%, 22.5% and 16.7% respectively. The isolates displayed the highest levels of antibiotic resistance (AR) against ampicillin (82.3%) and amoxicillin-clavulanic acid (74.2%) for E. coli, followed by cefoxitin (70.6%) for K. pneumoniae, whilst P. aeruginosa displayed 26.1% antibiotic resistance (AR) against both ampicillin and colistin sulphate. The colistin mcr-1 gene was harboured by 46.8%, 47.1% and 21.7%, E. coli, K. pneumonia and P. aeruginosa isolates respectively. Ten out of 62 (16.1%), 6/17 (35.3%), 4/23 (17.4%) isolates were phenotypically classified as ESBL E. coli, K. pneumoniae, and P. aeruginosa respectively. The ESBL-E. coli isolates respectively possessed blaCTX-M (60%), blaTEM (20%) and blaCTX-M-9 (10%) genes. The ESBL-K. pneumoniae harboured, blaCTX-M (50%), blaOXA (33%), blaCARB (17%), and blaCTX-M-9 (17%) genes respectively, whilst, P. aeruginosa isolates respectively carried blaTEM (75%), blaCTX-M (50%), blaOXA (25%) and blaCARB (25%) genes. Molecular analysis identified the blaCTX-Mβ-lactamase-encoding genes collectively from E. coli, P. aeruginosa, K. pneumoniae isolates. Colistin and β-lactamase genes were present in only 16.7%, 6.9%, and 2.9% of E. coli, K. pneumoniae, and P. aeruginosa isolates, respectively. A total of 17, 7 and 3 isolates for E. coli, K. pneumoniae and P. aeruginosa respectively carried both colistin and β-lactamase antibiotics resistant genes. This is a public health threat that points to a challenge in the treatment of infections caused by these zoonotic bacteria. Data generated from this study will contribute to formulation of new strategies for combating spread of E. coli, K. pneumoniae, and P. aeruginosa isolates as well as prevention of their AR development.

Situation Report on mcr-Carrying Colistin-Resistant Clones of Enterobacterales: A Global Update Through Human-Animal-Environment Interfaces

In the twenty-first century, antibiotic resistance (ABR) is one of the acute medical emergencies around the globe, overwhelming human-animal-environmental interfaces. Hit-or-mis use of antibiotics exacerbates the crisis of ABR, dispersing transferable resistance traits and challenging treatment regimens based on life-saving drugs such as colistin. Colistin is the highest priority critically important antimicrobials for human medicine, but its long use as a growth promoter in animal husbandry reduces clinical efficacy. Since 2015, the emergence and spread of mobile colistin resistance (mcr)-carrying colistin-resistant clones of Enterobacterales have been markedly sustained in both humans and animals, especially in developing countries. Hospital and community transmissions of mcr clones pose a high risk for infection prevention and outbreaks at the national and international levels. Several public health and limited one health studies have highlighted the genomic insights of mcr clones, clarifying the chromosomal sequence types (STs) and plasmid incompatibility (Inc) types. But this information is segregated into humans and animals, and rarely are environmental sectors complicating the understanding of possibly intercontinental and sectoral transmission of these clones. India is the hotspot for superbugs, including mcr-carrying colistin-resistant isolates that threaten cross-border transmission. The current review provided an up-to-date worldwide scenario of mcr-carrying STs and plasmid Inc types among the Gram-negative bacilli of Enterobacterales across human-animal-environmental interfaces and correlated with the available information from India.

A Review of Resistance to Polymyxins and Evolving Mobile Colistin Resistance Gene (mcr) among Pathogens of Clinical Significance

The global rise in antibiotic resistance in bacteria poses a major challenge in treating infectious diseases. Polymyxins (e.g., polymyxin B and colistin) are last-resort antibiotics against resistant Gram-negative bacteria, but the effectiveness of polymyxins is decreasing due to widespread resistance among clinical isolates. The aim of this literature review was to decipher the evolving mechanisms of resistance to polymyxins among pathogens of clinical significance. We deciphered the molecular determinants of polymyxin resistance, including distinct intrinsic molecular pathways of resistance as well as evolutionary characteristics of mobile colistin resistance. Among clinical isolates, Acinetobacter stains represent a diversified evolution of resistance, with distinct molecular mechanisms of intrinsic resistance including naxD, lpxACD, and stkR gene deletion. On the other hand, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa are usually resistant via the PhoP-PhoQ and PmrA-PmrB pathways. Molecular evolutionary analysis of mcr genes was undertaken to show relative relatedness across the ten main lineages. Understanding the molecular determinants of resistance to polymyxins may help develop suitable and effective methods for detecting polymyxin resistance determinants and the development of novel antimicrobial molecules.

Prevalence of antibiotic-resistant Gram-negative bacteria having extended-spectrum β-lactamase phenotypes in polluted irrigation-purpose wastewaters from Indian agro-ecosystems

Antibiotic resistance in bacteria has emerged as a serious public health threat worldwide. Aquatic environments including irrigation-purpose wastewaters facilitate the emergence and transmission of antibiotic-resistant bacteria and antibiotic resistance genes leading to detrimental effects on human health and environment sustainability. Considering the paramount threat of ever-increasing antibiotic resistance to human health, there is an urgent need for continuous environmental monitoring of antibiotic-resistant bacteria and antibiotic resistance genes in wastewater being used for irrigation in Indian agro-ecosystems. In this study, the prevalence of antibiotic resistance in Gram-negative bacteria isolated from irrigation-purpose wastewater samples from Sirmaur and Solan districts of Himachal Pradesh was determined. Bacterial isolates of genera Escherichia, Enterobacter, Hafnia, Shigella, Citrobacter, and Klebsiella obtained from 11 different geographical locations were found to exhibit resistance against ampicillin, amoxyclav, cefotaxime, co-trimoxazole, tobramycin, cefpodoxime and ceftazidime. However, all the isolates were sensitive to aminoglycoside antibiotic gentamicin. Enterobacter spp. and Escherichia coli showed predominance among all the isolates. Multidrug-resistance phenotype was observed with isolate AUK-06 (Enterobacter sp.) which exhibited resistant to five antibiotics. Isolate AUK-02 and AUK-09, both E. coli strains showed resistant phenotypes to four antibiotics each. Phenotypic detection revealed that six isolates were positive for extended-spectrum β-lactamases which includes two isolates from Enterobacter spp. and E. coli each and one each from Shigella sp. and Citrobacter sp. Overall, the findings revealed the occurrence of antibiotic resistant and ESBL-positive bacterial isolates in wastewaters utilized for irrigation purpose in the study area and necessitate continuous monitoring and precautionary interventions. The outcomes of the study would be of significant clinical, epidemiological, and agro-environmental importance in designing effective wastewater management and environmental pollution control strategies.

Electrochemical immunosensor for the detection of colistin in chicken liver

An innovative amperometric immunosensor has been developed to detect antibiotic colistin from the chicken liver. Colistin is a antibacterial peptide that has been barred for human consumption, but it is being commonly used as a veterinary drug, and as a feed additive for livestock. In the present work, an immunosensor was developed by immobilizing an anti-colistin Ab onto the CNF/AuNPs surface of the screen-printed electrode. The sensor records electrochemical response in the chicken liver spiked with colistin with CV. Additionally, the characterization of electrode surface was done with FE-SEM, FTIR, and EIS at each step of fabrication. The lower LOD was 0.89 μgKg-1, with a R 2 of 0.901 using CV. Further validation of the immunosensor was conducted using commercial chicken liver samples, by comparing the results to those obtained using traditional methods. The fabricated immunosensor showed high specificity towards colistin, which remained stable for 6 months but with a 13% loss in the initial CV current.