Due to the global emergence of antibiotic resistance, there has been an increase in research surrounding endolysins as an alternative therapeutic. Endolysins are phage-encoded enzymes, utilized by mature phage virions to hydrolyze the cell wall from within. There is significant evidence that proves the ability of endolysins to degrade the peptidoglycan externally without the assistance of phage. Thus, their incorporation in therapeutic strategies has opened new options for therapeutic application against bacterial infections in the human and veterinary sectors, as well as within the agricultural and biotechnology sectors. While endolysins show promising results within the laboratory, it is important to document their resistance, safety, and immunogenicity for in-vivo application. This review aims to provide new insights into the synergy between endolysins and antibiotics, as well as the formulation of endolysins. Thus, it provides crucial information for clinical trials involving endolysins.

Bacteriophages can be used successfully to treat pathogenic bacteria in the food chain including zoonotic pathogens that colonize the intestines of farm animals. However, harsh gastric conditions of low pH and digestive enzyme activities affect phage viability, and accordingly reduce their effectiveness. We report the development of a natural protective barrier suitable for oral administration to farm animals that confers acid stability before functional release of bead-encapsulated phages. Escherichia coli bacteriophage ZSEC5 is rendered inactive at pH 2.0 but encapsulation in chitosan–alginate bead with a honey and gelatin matrix limited titer reductions to 1 log10 PFU mL−1. The encapsulated phage titers were stable upon storage in water but achieved near complete release over 4–5 h in a simulated intestinal solution (0.1% bile salt, 0.4% pancreatin, 50 mM KH2PO4 pH 7.5) at 37 °C. Exposure of E. coli O157:H7 to the bead-encapsulated phage preparations produced a delayed response, reaching a maximal reductions of 4.2 to 4.8 log10 CFU mL−1 after 10 h at 37 °C under simulated intestinal conditions compared to a maximal reduction of 5.1 log10 CFU mL−1 at 3 h for free phage applied at MOI = 1. Bead-encapsulation is a promising reliable and cost-effective method for the functional delivery of bacteriophage targeting intestinal bacteria of farm animals.

Pseudomonas aeruginosa is an opportunistic gram-negative human pathogen that causes a wide range of infections, including nosocomial infections. Aside from the intrinsic and acquired antimicrobial resistance against many classes of antibiotics, P. aeruginosa can produce an extracellular polymeric matrix called “biofilm” that protects bacteria from antibiotics and harmful factors. Biofilm enables P. aeruginosa to develop chronic infections. This study assessed the inhibitory action of ZnO-nanoparticles against biofilms formed by multidrug-resistant P. aeruginosa strains. A collection of 24 clinical strains of P. aeruginosa were tested for their antimicrobial resistance against different antibiotics using the disk diffusion method. The antibiofilm activity of ZnO-NPs was assessed using the microtiter plate biofilm assay. The application of ZnO-NPs dramatically modulated the resistance profile and biofilm activity of P. aeruginosa. The combination of ZnO-NPs and meropenem showed synergistic antipseudomonal activity with lower MICs. The scanning electron microscope (SEM) micrographs revealed complete inhibition of biofilms treated with the meropenem–ZnO-NPs combination. Reduced expression of biofilm regulating genes lasR, pslA, and fliC was detected, reflecting the enhanced antibiofilm effect of ZnO-NPs. In vivo application of this antimicrobial mixture completely cured P. aeruginosa-induced keratitis in rats. Our findings represent a dual enhancement of antibacterial and antibiofilm activity via the use of meropenem–ZnO-NPs combination against carbapenem-resistant P. aeruginosa infections.

Escherichia coli (E. coli) is one of the most common pathogenic bacteria worldwide. Avian pathogenic E. coli (APEC) causes severe systemic disease in poultry (Colibacillosis), and accordingly, has an extreme risk to the poultry industry and public health worldwide. Due to the increased rate of multi-drug resistance among these bacteria, it is necessary to find an alternative therapy to antibiotics to treat such infections. Bacteriophages are considered one of the best solutions. This study aimed to isolate, characterize, and evaluate the potential use of isolated bacteriophages to control E. coli infections in poultry. Three novel phages against E. coli O18 were isolated from sewage water and characterized in vitro. The genome size of the three phages was estimated to be 44,776 bp, and the electron microscopic analysis showed that they belonged to the Siphoviridae family, in the order Caudovirales. Phages showed good tolerance to a broad range of pH and temperature. The complete genomes of three phages were sequenced and deposited into the GenBank database. The closely related published genomes of Escherichia phages were identified using BLASTn alignment and phylogenetic trees. The prediction of the open reading frames (ORFs) identified protein-coding genes that are responsible for functions that have been assigned such as cell lysis proteins, DNA packaging proteins, structural proteins, and DNA replication/transcription/repair proteins.

The challenge of antibiotic resistance has gained much attention in recent years due to the rapid emergence of resistant bacteria infecting humans and risking industries. Thus, alternatives to antibiotics are being actively searched for. In this regard, bacteriophages and their enzymes, such as endolysins, are a very attractive alternative. Endolysins are the lytic enzymes, which are produced during the late phase of the lytic bacteriophage replication cycle to target the bacterial cell walls for progeny release. Here, we cloned, expressed, and purified LysZC1 endolysin from Pseudomonas phage ZCPS1. The structural alignment, molecular dynamic simulation, and CD studies suggested LysZC1 to be majorly helical, which is highly similar to various phage-encoded lysozymes with glycoside hydrolase activity. Our endpoint turbidity reduction assay displayed the lytic activity against various Gram-positive and Gram-negative pathogens. Although in synergism with EDTA, LysZC1 demonstrated significant activity against Gram-negative pathogens, it demonstrated the highest activity against Bacillus cereus. Moreover, LysZC1 was able to reduce the numbers of logarithmic-phase B. cereus by more than 2 log₁₀ CFU/mL in 1 h and also acted on the stationary-phase culture. Remarkably, LysZC1 presented exceptional thermal stability, pH tolerance, and storage conditions, as it maintained the antibacterial activity against its host after nearly one year of storage at 4 °C and after being heated at temperatures as high as 100 °C for 10 min. Our data suggest that LysZC1 is a potential candidate as a therapeutic agent against bacterial infection and an antibacterial bio-control tool in food preservation technology.

Background: Ankylosing spondylitis (AS) is a destructive inflammatory disease which was reported to have the longest diagnostic delay among the inflammatory rheumatic disease. This lag period have a great impact on the clinical outcome and socioeconomic state of the patients. With the advent of tumor necrosis factor-α (TNF-α) inhibitors, early diagnosis in AS has become important(1). Objectives: to evaluate the period from symptom onset to diagnosis of AS in Egyptian patients and to examine possible reasons for delayed diagnosis and its impact on the economic and social life of the patients. Methods: The study included 87 AS patients diagnosed according to the Assessment of Spondyloarthritis international Society (ASAS) criteria (2). A face-to-face interview was applied to take medical history, and a questionnaire that contains some clinical aspects of disease was used. Diagnosis delay was described as the gap between first AS symptom and correct diagnosis of AS. Clinical and functional assessment of axial SpA measured by Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Functional Index (BASFI), Bath Ankylosing Spondylitis Metrology Index (BASMI). The direct medical cost during years of delay (including costs of medical consultations, medications, investigations, physiotherapy and surgical treatment) had been estimated by Egyptian pound. Results: The study included 87 AS patients with mean age (30.03±8.3), 70 male (80.5%) and 17 female (19.5%). Mean delay in diagnosis was(5.7 ±4.9) years. Mean of diagnostic delay for patient diagnosed before 2010 is (14±4.4) and that of patients diagnosed after 2010 is (3.5±1.8) with significant difference between both (p value<0.0001). The main cause of delay was incorrect diagnosis as follow degenerative disc disease (43/87, 49.4%), non-specific back pain (31/87, 35.6%), rheumatoid arthritis (10/87,11.5%), rheumatic fever (2/87, 2.3%) and tuberculosis of spine (1/87, 1.1%). The mean of the medical visits was (6±5.4). Most incorrect initial diagnoses were made by orthopedicians (57.9%), followed by neurologists (22.2%) followed by rheumatologist (10%) and general phyisicians (9.9%). Absence of extra-articular manifestations, negative family history and juvenile age are significantly associated with diagnostic delay. Delay in diagnosis is significantly associated with higher disease activity index(BASDAI), functional index (BASFI), and damage index(BASMI). The mean of the costs during years of delay is (15671.3±546.1) with the mean of cost per each year delay (660.9±6.6) with high significant association between the cost and longer delay in diagnosis (<0.0001). Regarding work ability, we found that(32.2%) are fit for work, unfit (29.9%), partially fit (37.9%) with high significant difference between ability of work and shorter delay. Regarding social effect, 40.2 % of patients developed negative effect on social life with significant association to diagnostic delay (0.004). Conclusion: Our study confirmed the importance of early diagnosis of AS due to its impact on patient’s health outcome and socioeconomic state.We recommend to increase the awareness about the disease among healthcare professionals in our region. References: [1]Sykes M. et al: Diagnostic delay in patients with rheumatoid arthritis, psoriatic arthritis and ankylosing spondylitis; Ann Rheum Dis.2015;74:e44. [2]Rudwaleit M. et al: The development of Assessment of Spondyloarthritis international Society classification criteria for axial spondyloarthritis; Ann Rheum Dis, 68 (2009), pp.777-783. Disclosure of Interests: None declared