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

Abstract

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.

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

“…Many clinically relevant isolates of E. cloacae exhibit resistance to key β-lactam antibiotics, such as ampicillin and amoxicillin, posing significant challenges in their infection management, particularly in immunocompromised patients, and can result in serious health complications, including bacteremia, endocarditis, and mortality [28]. Specific lytic phages against clinical isolates of E. cloacae have been previously isolated [29][30][31][32][33] and assessed for their efficacy. ECC isolates in Taiwan showed greater resistance to ertapenem compared to E. coli and K. pneumoniae isolates [34].…”

Bacteriocins and Bacteriophages as Dual Biological Players for Food Safety Applications

“…Other researchers have reported the beneficial effects of lytic phages on several pathogenic species in various food matrices, such as the inhibition of Enterobacter cloacae growth in pasteurized milk and yogurt by vB_EclM-EP1 and vB_EclM-EP2 phages [92]. Similarly, two multidrug-resistant strains of Vibrio parahaemolyticus and Vibrio cholerae isolated from water samples were effectively lysed by two phages, vB_VpM_SA3V and vB_VcM_SA3V, belonging to the former Myoviridae family [102].…”

“…Bacteriophages have been successfully used in the treatment and diagnosis of plant diseases and in the biocontrol of phytopathogenic bacteria [87,88]. Phages have also been used in wastewater treatment [89] and are widely used for pathogen control and detection in the dairy industry [90][91][92].…”