Exploring the potential efficacy of phage therapy for biocontrol of foodborne pathogenic extensively drug-resistant Escherichia coli in gastrointestinal tract of rat model

Isolation and Characterization of Novel Escherichia coli O157:H7 Phage SPEC13 as a Therapeutic Agent for E. coli Infections In Vitro and In Vivo

Escherichia coli O157:H7 is a recognized food-borne pathogen causing severe food poisoning at low doses. Bacteriophages (phages) are FDA-approved for use in food and are suggested as natural preservatives against specific pathogens. A novel phage must be identified and studied to develop a new natural preservative or antimicrobial agent against E. coli O157:H7. The phage SPEC13 displayed broad host range and was classified within the Ackermannviridae family based on its observed characteristics by a TEM and genome analysis. In 10 min, this phage achieves a remarkable 93% adsorption rate with the host. Its latency period then lasts about 20 min, after which it bursts, releasing an average of 139 ± 3 PFU/cell. It exhibited robustness within a pH range of 4 to 12, indicating resilience under diverse environmental circumstances. Furthermore, SPEC13 demonstrated stability at an ambient temperature up to 60 °C. A whole genome and phylogenetics analysis revealed that SPEC13 is a novel identified phage, lacking a lysogenic life cycle, antibiotic resistance genes, or genes associated with virulence, thereby presenting a promising biological agent for therapeutic application. Animal studies showed that SPEC13 effectively controlled the growth of harmful bacteria, resulting in a significant improvement in colon health, marked by reduced swelling (edema) and tissue damage (mucosal injury). The introduction of SPEC13 resulted in a substantial decrease in quantities of E. coli O157:H7, reducing the bacterial load to approximately 5 log CFU/g of feces. In conclusion, SPEC13 emerges as a promising inclusion in the array of phage therapy, offering a targeted and efficient approach for addressing bacterial infections.

Characterization of GQA as a novel β-lactamase inhibitor of CTX-M-15 and KPC-2 enzymes

β-lactam resistance is a significant global public health issue. Outbreaks of bacteria resistant to extended-spectrum β-lactams and carbapenems are serious health concerns that not only complicate medical care but also impact patient outcomes. The primary objective of this work was to express and purify two soluble recombinant representative serine β‑lactamases using Escherichia coli strain as an expression host and pET101/D as a cloning vector. Furthermore, a second objective was to evaluate the potential, innovative, and safe use of galloylquinic acid (GQA) from Copaifera lucens as a potential β-lactamase inhibitor.In the present study, blaCTX-M-15 and blaKPC-2 represented genes encoding for serine β-lactamases that were cloned from parent isolates of E. coli and K. pneumoniae, respectively, and expression as well as purification were performed. Moreover, susceptibility results demonstrated that recombinant cells became resistant to all test carbapenems (MICs; 64-128 µg/mL) and cephalosporins (MICs; 128-512 µg/mL). The MICs of the tested β-lactam antibiotics were determined in combination with 4 µg/mL of GQA, clavulanic acid, or tazobactam against E. coli strains expressing CTX-M-15 or KPC-2-β-lactamases. Interestingly, the combination with GQA resulted in an important reduction in the MIC values by 64-512-fold to the susceptible range with comparable results for other reference inhibitors. Additionally, the half-maximal inhibitory concentration of GQA was determined using nitrocefin as a β-lactamase substrate. Data showed that the test agent was similar to tazobactam as an efficient inhibitors of the test enzymes, recording smaller IC50 values (CTX-M-15; 17.51 for tazobactam, 28.16 µg/mL for GQA however, KPC-2; 20.91 for tazobactam, 24.76 µg/mL for GQA) compared to clavulanic acid. Our work introduces GQA as a novel non-β-lactam inhibitor, which interacts with the crucial residues involved in β-lactam recognition and hydrolysis by non-covalent interactions, complementing the enzyme's active site. GQA markedly enhanced the potency of β-lactams against carbapenemase and extended-spectrum β-lactamase-producing strains, reducing the MICs of β-lactams to the susceptible range. The β-lactamase inhibitory activity of GQA makes it a promising lead molecule for the development of more potent β-lactamase inhibitors.

Bacteriophages in nature: recent advances in research tools and diverse environmental and biotechnological applications

Bacteriophages infect and replicate within bacteria and play a key role in the environment, particularly in microbial ecosystems and bacterial population dynamics. The increasing recognition of their significance stems from their wide array of environmental and biotechnological uses, which encompass the mounting issue of antimicrobial resistance (AMR). Beyond their therapeutic potential in combating antibiotic-resistant infections, bacteriophages also find vast applications such as water quality monitoring, bioremediation, and nutrient cycling within environmental sciences. Researchers are actively involved in isolating and characterizing bacteriophages from different natural sources to explore their applications. Gaining insights into key aspects such as the life cycle of bacteriophages, their host range, immune interactions, and physical stability is vital to enhance their application potential. The establishment of diverse phage libraries has become indispensable to facilitate their wide-ranging uses. Consequently, numerous protocols, ranging from traditional to cutting-edge techniques, have been developed for the isolation, detection, purification, and characterization of bacteriophages from diverse environmental sources. This review offers an exploration of tools, delves into the methods of isolation, characterization, and the extensive environmental applications of bacteriophages, particularly in areas like water quality assessment, the food sector, therapeutic interventions, and the phage therapy in various infections and diseases.

The Role of Bacteriophages in the Gut Microbiota: Implications for Human Health

Bacteriophages (phages) are nano-sized viruses characterized by their inherent ability to live off bacteria. They utilize diverse mechanisms to absorb and gain entry into the bacterial cell wall via the release of viral genetic material, which uses the replication mechanisms of the host bacteria to produce and release daughter progeny virions that attack the surrounding host cells. They possess specific characteristics, including specificity for particular or closely related bacterial species. They have many applications, including as potential alternatives to antibiotics against multi-resistant bacterial pathogens and as control agents in bacteria-contaminated environments. They are ubiquitously abundant in nature and have diverse biota, including in the gut. Gut microbiota describes the community and interactions of microorganisms within the intestine. As with bacteria, parasitic bacteriophages constantly interact with the host bacterial cells within the gut system and have obvious implications for human health. However, it is imperative to understand these interactions as they open up possible applicable techniques to control gut-implicated bacterial diseases. Thus, this review aims to explore the interactions of bacteriophages with bacterial communities in the gut and their current and potential impacts on human health.