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Two bacteriophages of Clostridium difficile
Abstract:
Two temperate bacteriophages of differing morphology and host range were isolated by screening 94 isolates of Clostridium difficile. Phage 41 had a 300-nm flexible tail, whereas phage 56 had a shorter tail with a contractile sheath. Electron microscopy of phage 56 lysates exposed to elevated magnesium concentrations showed small virus-like particles which were 21 nm in diameter. The addition of MgCl2 to semisolid agar overlays enhanced both the titer and plaque size of phage 56. Phage 56 was more temperature labile than phage 41 and demonstrated unusual lability in buffer at pH 7.0. One-step growth and adsorption experiments revealed that both phages had latent periods of about 60 min, but phage 56 adsorbed to its indicator strain more efficiently. Phage 56, which was obtained from a toxigenic strain of C. difficile, was used to lysogenize its nontoxigenic indicator strain, but no conversion to toxigenicity was observed in this strain.
Insights
Two temperate bacteriophages targeting Clostridium difficile were identified. Phage 56, with unique morphology and magnesium sensitivity, showed efficient adsorption but did not confer toxigenicity.
Area of Science:
- Microbiology
- Virology
- Bacteriology
Background:
- Clostridium difficile infections are a significant healthcare concern.
- Bacteriophages are viruses that infect bacteria and are being explored as therapeutic agents.
- Understanding bacteriophage characteristics is crucial for their potential application.
Purpose of the Study:
- To isolate and characterize temperate bacteriophages infecting Clostridium difficile.
- To compare the morphology, growth, and adsorption properties of isolated phages.
- To investigate the potential of phage 56 in lysogenizing C. difficile and affecting toxigenicity.
Main Methods:
- Screening of 94 Clostridium difficile isolates for temperate bacteriophages.
- Morphological characterization using electron microscopy.
- One-step growth, adsorption experiments, and lysogenization assays.
- Assessment of phage stability under varying magnesium concentrations and pH.
Main Results:
- Isolation of two distinct temperate bacteriophages, Phage 41 and Phage 56.
- Phage 41 possessed a flexible tail (300 nm), while Phage 56 had a contractile sheath tail and smaller virus-like particles (21 nm) under specific conditions.
- Magnesium chloride (MgCl2) enhanced Phage 56 titer and plaque size.
- Phage 56 exhibited greater temperature and pH lability compared to Phage 41.
- Both phages had a ~60-minute latent period, with Phage 56 showing more efficient adsorption.
- Lysogenization of a nontoxigenic strain with Phage 56 did not result in toxigenicity conversion.
Conclusions:
- Two novel temperate bacteriophages of Clostridium difficile were characterized.
- Phage 56 displays unique morphological and physicochemical properties, including magnesium enhancement and increased lability.
- Phage 56 efficiently infects its host but does not transfer toxigenicity, suggesting potential for targeted therapy without altering bacterial virulence.