Anaerobiosis, a neglected factor in phage-bacteria interactions.

IMPORTANCE: Many parameters affect phage-bacteria interaction. Some of these parameters depend on the environment in which the bacteria are present. Anaerobiosis effect on phage infection in facultative anaerobic bacteria has not yet been studied. The absence of oxygen triggers metabolic changes in facultative bacteria and this affects phage infection and viral life cycle. Understanding how an anaerobic environment can alter the behavior of phages during infection is relevant for the phage therapy success.

Mucin-induced surface dispersal of Staphylococcus aureus and Staphylococcus epidermidis via quorum-sensing dependent and independent mechanisms.

Nasopharyngeal carriage of staphylococci spreads potentially pathogenic strains into (peri)oral regions and increases the chance of cross-infections. Some laboratory strains can also move rapidly on hydrated agar surfaces, but the biological relevance of these observations is not clear. Using soft-agar [0.3% (wt/vol)] plate assays, we demonstrate the rapid surface dispersal of (peri)oral isolates of Staphylococcus aureus and Staphylococcus epidermidis and closely related laboratory strains in the presence of mucin glycoproteins. Mucin-induced dispersal was a stepwise process initiated by the passive spreading of the growing colonies followed by their rapid branching (dendrites) from the colony edge. Although most spreading strains used mucin as a growth substrate, dispersal was primarily dependent on the lubricating and hydrating properties of the mucins. Using S. aureus JE2 as a genetically tractable representative, we demonstrate that mucin-induced dendritic dispersal, but not colony spreading, is facilitated by the secretion of surfactant-active phenol-soluble modulins (PSMs) in a process regulated by the agr quorum-sensing system. Furthermore, the dendritic dispersal of S. aureus JE2 colonies was further stimulated in the presence of surfactant-active supernatants recovered from the most robust (peri)oral spreaders of S. aureus and S. epidermidis. These findings suggest complementary roles for lubricating mucins and staphylococcal PSMs in the active dispersal of potentially pathogenic strains from perioral to respiratory mucosae, where gel-forming, hydrating mucins abound. They also highlight the impact that interspecies interactions have on the co-dispersal of S. aureus with other perioral bacteria, heightening the risk of polymicrobial infections and the severity of the clinical outcomes. IMPORTANCE: Despite lacking classical motility machinery, nasopharyngeal staphylococci spread rapidly in (peri)oral and respiratory mucosa and cause cross-infections. We describe laboratory conditions for the reproducible study of staphylococcal dispersal on mucosa-like surfaces and the identification of two dispersal stages (colony spreading and dendritic expansion) stimulated by mucin glycoproteins. The mucin type mattered as dispersal required the surfactant activity and hydration provided by some mucin glycoproteins. While colony spreading was a passive mode of dispersal lubricated by the mucins, the more rapid and invasive form of dendritic expansion of Staphylococcus aureus and Staphylococcus epidermidis required additional lubrication by surfactant-active peptides (phenol-soluble modulins) secreted at high cell densities through quorum sensing. These results highlight a hitherto unknown role for gel-forming mucins in the dispersal of staphylococcal strains associated with cross-infections and point at perioral regions as overlooked sources of carriage and infection by staphylococci.

SalmoFree® Phage Additive Proves Its Safety for Laying Hens.

Background: The avian pathogen Salmonella Gallinarum causes avian typhosis in laying hens, leading to high mortality rates among adult birds, which poses a significant problem in the poultry industry. Various products, such as vaccines, antibiotics, probiotics, and disinfectants, are commonly used to prevent and control the disease on farms. An alternative to these products is the use of bacteriophages, which may effectively prevent the colonization of S. Gallinarum. Materials and Methods: This study evaluated the safety of SalmoFree®, a bacteriophage cocktail, administered to 276 laying hens from the first week of age until the 28th week. The hens were divided into two groups: a control group (138 birds) and a treatment group (138 birds). Over the 28-week period, eight doses of SalmoFree® (∼1010 UFP per bird) were administered via drinking water in a controlled environment. Results: The results indicate that the consumption of SalmoFree® has no adverse effects on bird health or zootechnical parameters. Additionally, there is a trend toward improving weight homogeneity (up to 19%), feed conversion (up to 68%), and egg weight (up to 2.7%). The detection of phages by PCR in cloacal swabs suggests that they persist in birds for 2 to 8 weeks post-ingestion. Furthermore, phages were detected in organs and eggshells, indicating that they provide protection beyond the gut. Conclusion: The study demonstrates that SalmoFree® is safe for use in laying hens and may offer additional benefits, such as improved zootechnical parameters and extended protection against S. Gallinarum through the persistence of bacteriophages in the birds.