Browsing by Author "Srishti Singh"

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Current update on the antibiotic resistance profile and the emergence of colistin resistance in Enterobacter isolates from hospital-acquired infections
(Elsevier B.V., 2025) Srishti Singh; Alok Kumar Singh; Sudhir Kumar Singh; Virendra Bahadur Yadav; Akshay Kumar; Gopal Nath
Introduction: Bacterial pathogens are becoming a growing concern as antibiotic resistance among Gram-negative bacteria rises globally. The gram-negative, facultative anaerobic, rod-shaped bacteria belonging to the Enterobacteriaceae family, Enterobacter is a nosocomial pathogen, having ubiquitous distribution in natural environments, including sewage and dairy products. These bacteria increasingly exhibit a multidrug resistance phenotype, thus becoming resilient to available treatment therapies. The fact mentioned above has resulted in them being included in the “ESKAPE” group of opportunistic pathogens, which represents a group for which no effective therapeutic options would be available in a given scenario. So, this study aimed to identify antibiotic resistance patterns in Enterobacter species collected from the bacteriological section of the Institute of Medical Sciences, Banaras Hindu University, Varanasi. Materials and Methods: Fifty-one isolates were collected from clinical samples, including urine, pus, blood, cerebrospinal fluid, sputum, and stool. All isolates were phenotypically identified using VITEK-2 automated systems (ID GNB cards). Additionally, the isolates were genotypically characterised with species-specific primers via PCR, and whole genome sequencing was performed for two isolates, followed by antimicrobial susceptibility testing using the Kirby-Bauer disc diffusion method. Concurrently, broth dilution methods were used to determine the minimum inhibitory concentration (MIC) according to CLSI 2020 guidelines. The Multiple Antibiotic Resistance Index (MARI) was calculated by dividing the number of drugs to which the bacterial isolate is resistant by the total number of antibiotics used in the experiment. Results: The highest resistance rates were observed against levofloxacin (94 %), ciprofloxacin, and ampicillin, with 92 % (47/51) of isolates demonstrating resistance. Cefazolin also exhibited a high resistance rate, with 82 % (42/51) of resistant isolates. Notably, 96.07 % of isolates showed a multiple antibiotic resistance (MAR) index greater than 0.2, indicating a significant burden of multidrug-resistant Gram-negative bacteria. In contrast, 21.56 % had an index greater than 1.0, indicating resistance to all antibiotics tested. Conclusion: This paper highlights the latest information regarding drug resistance patterns in Enterobacter isolates. The last resort for treating gram-negative bacteria is increasingly losing its effectiveness due to the emergence of colistin-resistant strains. Therefore, alternative therapies, such as phage treatment or other antimicrobial agents, must be developed to combat these superbugs. © 2025 The Authors
Efficacy of bacteriophage cocktails administered through mucosal and non-mucosal routes for urinary tract infections caused by Enterobacter cloacae: A preclinical study
(Academic Press, 2025) Srishti Singh; Alok Kumar Singh; Alakh Narayan Singh; Sudhir Kumar Singh; Virendra Bahadur Yadav; Mayank Gangwar; Minakshi Sahu; Deepak Kumar; Gopal Nath
This preclinical study assessed the effectiveness of a phage cocktail in completely curing Enterobacter cloacae-associated urinary tract infections (UTIs) in a mouse model, employing various routes and dosages (both in quantity and frequency). Three lytic phages, designated ΦENT1, ΦENT2, and ΦENT3, were identified and characterised phenotypically using transmission electron microscopy (TEM) and genotypically through ERIC and restriction enzyme analysis. To induce a UTI, ten groups of female Swiss albino mice were inoculated with 100 μL containing 1 × 109 CFU/mL via the urethral route with E. cloacae GNENT11213. The mice were subsequently treated with the phage cocktail via subcutaneous, oral, transurethral, and rectal routes. The efficacy of these routes was optimised at two doses of phages, namely 1 × 109 PFU/mL (5 mice) and 1 × 105 PFU/mL (5 mice). Furthermore, the levels of Endotoxins and Interleukin-6 (IL-6) were measured to assess the negative impact of phage therapy. Our findings indicated that E. cloacae GNENT11213 could be effectively eliminated with one dosage of 1 × 109Plaque-Forming Units per mouse (PFU/mouse) and two doses of the phage cocktail containing 1 × 105 PFU/mouse administered through the urethra (local mucosa). Interestingly, higher concentrations of phage particles and multiple doses were necessary for other mucosal routes, such as oral and rectal administration, to effectively eradicate E. cloacae GNENT11213 at any stage of acute illness UTI. Furthermore, phage treatment did not significantly alter the levels of IL-6 and Endotoxins. Non-mucosal routes, such as subcutaneous, were ineffective in curing the infection. © 2025 Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.
In vitro efficacy of bacteriophage and colistin combinations in eradicating biofilm formed by colistin-resistant Enterobacter cloacae complex
(Elsevier B.V., 2025) Srishti Singh; Alok Kumar Singh; Virendra Bahadur Yadav; Sudhir Kumar Singh; Minakshi Sahu; Alakh Narayan Singh; Gopal Nath
In the case of dry antibiotic pipelines and the emergence of resistance against last-resort antibiotics, such as colistin, alternative medicinal techniques have been necessitated. In this context, the potential of phages as a viable alternative to antibiotics is a beacon of hope. Phage and antibiotic combination therapy is a compelling solution to the problem of phage or bacterial mutant generation. In most studies, phage and antibiotic combinations were used simultaneously. Only a few phages have been recently utilised before antibiotics, significantly reducing the bacterial load in vitro and in vivo. Therefore, we investigated the additive action of phage antibiotic combinations in preventing biofilm formation against three different colistin-resistant clinical isolates of the Enterobacter cloacae complex, specifically Enterobacter cloacae and Enterobacter hormaechei, at various time points with varying phage concentrations. We used different phage concentrations and sub-MICs of colistin combinations to determine the optimal phage concentration that shows synergy against three different clinical isolates of the Enterobacter cloacae complex. We also investigated the optimal time for applying antibiotics after phage treatment to eradicate Enterobacter cloacae complex in both planktonic and biofilm states. The cross-colistin susceptibility of colistin-resistant strain after co-treatment with SIM (Phage antibiotic simultaneous) and AF (Antibiotic added 8 h before phage) was also evaluated using the broth dilution method. In brief, applying phage before 8 h or 6 h of colistin, i.e. PF (Phage first followed by antibiotics) treatment at a dosage of 106 PFU/mL, was an effective sequential therapy for eliminating the biofilm and the planktonic form of Enterobacter cloacae complex. The Institutional Ethics Committee of Banaras Hindu University (Institute of Medical Sciences), Varanasi, with reference number Dean/2024/IAEC/6876, has approved this in vitro study. © 2025 The Authors
Phage therapy: A reinvigorated treatment against multidrug-resistant bacteria
(Nova Science Publishers, Inc., 2022) Srishti Singh; Alok Kumar Singh; Gopal Nath
ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.) is an abbreviation for their names and a reference to their capacity to evade the effects of routinely used antibiotics through mechanisms that have evolved through time. Under the theme "Antibiotic resistance: no action today, no treatment tomorrow," the World Health Organization on World Health Day 2011 emphasized the challenges of antibiotic resistance. Bacteriophages are bacterium-infecting viruses that destroy bacteria without harming human cells. As a result, they're thought to be able to cure bacterial infections alone or with antibiotics. Bacteriophages have evolved unique proteins that stop specific cellular processes to dedicate bacterial host metabolism to phage replication over time. In this moment of rapid development of MDR (Multidrug Resistance) bacterial infections and a scarcity of novel antibiotics to tackle these pathogens, phage therapy might be a good alternative to antimicrobial chemotherapy and helpful in achieving good health and well-being that is Sustainable Development Goal (SDG). © 2022 Nova Science Publishers, Inc..