Characterization of a novel, biofilm dispersing, lytic bacteriophage against drug-resistant Enterobacter cloacae

Therapeutic Potential of a Novel Lytic Phage, vB_EclM_ECLFM1, against Carbapenem-Resistant Enterobacter cloacae

The global rise of multidrug-resistant Enterobacter cloacae strains, especially those that are resistant to carbapenems and produce metallo-β-lactamases, poses a critical challenge in clinical settings owing to limited treatment options. While bacteriophages show promise in treating these infections, their use is hindered by scarce resources and insufficient genomic data. In this study, we isolated ECLFM1, a novel E. cloacae phage, from sewage water using a carbapenem-resistant clinical strain as the host. ECLFM1 exhibited rapid adsorption and a 15-min latent period, with a burst size of approximately 75 PFU/infected cell. Its genome, spanning 172,036 bp, was characterized and identified as a member of Karamvirus. In therapeutic applications, owing to a high multiplicity of infection, ECLFM1 showed increased survival in zebrafish infected with E. cloacae. This study highlights ECLFM1's potential as a candidate for controlling clinical E. cloacae infections, which would help address challenges in treating multidrug-resistant strains and contribute to the development of alternative treatments.

Isolation, characterization, and application of lytic bacteriophages for controlling Enterobacter cloacae complex (ECC) in pasteurized milk and yogurt

Reducing bacterial pathogen contamination not only improves overall global public health but also diminishes food waste and loss. The use of lytic bacteriophages (phages) that infect and kill bacteria could be a beneficial tool for suppressing bacterial growth during dairy products storage time. Four Enterobacter cloacae (E. cloacae) complex isolates which were previously isolated from contaminated dairy products were used to identify lytic phages in wastewater. Phages specific to multi-drug resistant (MDR) E. cloacae complex 6AS1 were isolated from local sewage. Two novel phages vB_EclM-EP1 and vB_EclM-EP2 were identified as myoviral particles and have double-stranded DNA genome. Their host range and lytic capabilities were detected using spot test and efficiency of plating (EOP) against several bacterial isolates. The phages had a latent period of 30 min, and a large burst size of about 100 and 142 PFU/cell for vB_EclM-EP1 and vB_EclM-EP2, respectively. Both phages were viable at pH ranging 5-9 and stable at 70 °C for 60 min. The individual phages and their cocktail preparations (vB_EclM-EP1 and vB_EclM-EP2) reduced and inhibited the growth of E. cloacae complex 6AS1 during challenge test in milk and yogurt samples. These results indicate that the E. cloacae complex-specific phages (vB_EclM-EP1 and vB_EclM-EP2) have a potential application as microbicidal agents in packaged milk and milk derivatives during storage time. In addition, our environment is a rich sources of lytic phages which have potential use in eliminating multidrug-resistant isolates in food industry as well as in biocontrol.

Genome Characterization of the Novel Lytic Enterobacter cloacae Phage vB_EclM_Q7622

Enterobacter cloacae is a widespread opportunistic pathogen that causes urinary tract infection. The abuse of antibiotics enabled multidrug-resistant strains to spread. Bacteriophage therapy is a naturally, safe, and efficient alternative treatment technology against multi-resistant bacteria. In this study, a virulent phage vB_EclM_Q7622 (Q7622) was isolated from the sewage of Jiangcun poultry market in Guangzhou city. Transmission electron microscopy indicated that Q7622 had an icosahedral head (97.8 ± 5.6 nm in diameter) and a short, contractile tail (113.7 ± 4.5 nm). Its double-stranded DNA genome is composed of 173,871 bp with a GC content of 40.02%. It possesses 297 open reading frames and 9 tRNAs. No known virulence and resistance genes were detected, indicated that phage Q7622 could be used for pathogens prevention and control safely. Comparative genomic and phylogenetic analysis showed that Q7622 was highly similar to the phages vB_EclM_CIP9 and vB_EhoM-IME523. The highest nucleotide similarity between Q7622 and the similar phages in NCBI calculated by pyANI and VIRIDIC were 94.9% and 89.1% with vB_EhoM-IME523 respectively, below 95%. Thus, according to the result of nucleotide similarity calculation results, Q7622 was a novel virulent Enterobacter cloacae phage strain of the genus Kanagawavirus.

Two Newly Isolated Enterobacter-Specific Bacteriophages: Biological Properties and Stability Studies

In an era of antibiotic therapy crisis caused by spreading antimicrobial resistance, and when recurrent urinary tract infections constitute a serious social and medical problem, the isolation and complex characterization of phages with a potential therapeutic application represents a promising solution. It is an inevitable, and even a necessary direction in the development of current phage research. In this paper, we present two newly isolated myoviruses that show lytic activity against multidrug-resistant clinical isolates of Enterobacter spp. (E. cloacae, E. hormaechei, and E. kobei), the genomes of which belong to a poorly represented phage group. Both phages were classified as part of the Tevenvirinae subfamily (Entb_43 was recognized as Karamvirus and Entb_45 as Kanagawavirus). Phage lytic spectra ranging from 40 to 60% were obtained. The most effective phage-to-bacteria ratios (MOI = 0.01 and MOI = 0.001) for both the phage amplification and their lytic activity against planktonic bacteria were also estimated. Complete adsorption to host cells were obtained after about 20 min for Entb_43 and 10 min for Entb_45. The phage lysates retained their initial titers even during six months of storage at both -70 °C and 4 °C, whereas storage at 37 °C caused a complete loss in their activity. We showed that phages retained their activity after incubation with solutions of silver and copper nanoparticles, which may indicate possible synergistic antibacterial activity. Moreover, a significant reduction in phage titers was observed after incubation with a disinfectant containing octenidinum dihydrochloridum and phenoxyethanol, as well as with 70% ethanol. The observed maintenance of phage activity during incubation in a urine sample, along with other described properties, may suggest a therapeutic potential of phages at the infection site after intravesical administration.