The zebrafish embryo model: unveiling its potential for investigating phage therapy against methicillin-resistant Staphylococcus aureus infection.

Staphylococcus aureus is a pathogenic bacterium responsible for a broad spectrum of infections, including cutaneous, respiratory, osteoarticular, and systemic infections. It poses a significant clinical challenge due to its ability to develop antibiotic resistance. This resistance limits therapeutic options, increases the risk of severe complications, and underscores the urgent need for new strategies to address this threat, including the investigation of treatments complementary to antibiotics. The evaluation of novel antimicrobial agents often employs animal models, with the zebrafish embryo model being particularly interesting for studying host-pathogen interactions, establishing itself as a crucial tool in this field. For the first time, this study presents a zebrafish embryo model for the in vivo assessment of bacteriophage efficacy against S. aureus infection. A localized infection was induced by microinjecting either methicillin-resistant S. aureus (MRSA) or methicillin-susceptible S. aureus (MSSA). Subsequent treatments involved administering either bacteriophage, vancomycin (the reference antibiotic for MRSA), or a combination of both via the same route to explore potential synergistic effects. Our findings indicate that the bacteriophage was as effective as vancomycin in enhancing survival rates, whether used alone or in combination. Moreover, bacteriophage treatment appears to be even more effective in reducing the bacterial load in S. aureus-infected embryos post-treatment than the antibiotic. Our study validates the use of the zebrafish embryo model and highlights its potential as a valuable tool in assessing bacteriophage efficacy treatments in vivo.

Isolation and Characterization of New Bacteriophages against Staphylococcal Clinical Isolates from Diabetic Foot Ulcers.

Staphylococcus sp. is the most common bacterial genus in infections related to diabetic foot ulcers (DFUs). The emergence of multidrug-resistant bacteria places a serious burden on public health systems. Phage therapy is an alternative treatment to antibiotics, overcoming the issue of antibiotic resistance. In this study, six phages (SAVM01 to SAVM06) were isolated from effluents and were used against a panel of staphylococcal clinical samples isolated from DFUs. A genomic analysis revealed that the phages belonged to the Herelleviridae family, with sequences similar to those of the Kayvirus genus. No lysogeny-associated genes, known virulence or drug resistance genes were identified in the phage genomes. The phages displayed a strong lytic and antibiofilm activity against DFU clinical isolates, as well as against opportunistic pathogenic coagulase-negative staphylococci. The results presented here suggest that these phages could be effective biocontrol agents against staphylococcal clinical isolates from DFUs.