Isolation of lytic bacteriophages and their relationships with the adherence genes of Staphylococcus saprophyticus.

OBJECTIVE: This study aimed to introduce a lytic bacteriophage against Staphylococcus saprophyticus from wastewater in Gorgan, northern Iran. RESULTS: The vB_SsapS-46 phage was isolated from urban wastewater and formed round and clear plaques on bacterial culture. It was visualized by electron microscopy and had a large head (approximately 106 nm) and a long tail (approximately 150 nm), indicating that it belongs to the Siphoviridae family. The host range of vB_SsapS-46 was determined using a spot test on 35 S. saprophyticus clinical isolates, and it was able to lyse 12 of the 35 clinical isolates (34%). Finally, the relationship between phage sensitivity and adherence genes was assessed, revealing no significant correlation between phage sensitivity and the frequency of adherence genes. The vB_SsapS-46 phage can be used alone or in a mixture in future studies to control urinary tract infections caused by this bacterium, especially in the elimination of drug-resistant pathogens.

Bacteriophage-driven emergence and expansion of Staphylococcus aureus in rodent populations.

Human activities such as agriculturalization and domestication have led to the emergence of many new pathogens via host-switching events between humans, domesticated and wild animals. Staphylococcus aureus is a multi-host opportunistic pathogen with a global healthcare and economic burden. Recently, it was discovered that laboratory and wild rodents can be colonised and infected with S. aureus, but the origins and zoonotic potential of rodent S. aureus is unknown. In order to trace their evolutionary history, we employed a dataset of 1249 S. aureus genome sequences including 393 of isolates from rodents and other small mammals (including newly determined sequences for 305 isolates from 7 countries). Among laboratory mouse populations, we identified multiple widespread rodent-specific S. aureus clones that likely originated in humans. Phylogeographic analysis of the most common murine lineage CC88 suggests that it emerged in the 1980s in laboratory mouse facilities most likely in North America, from where it spread to institutions around the world, via the distribution of mice for research. In contrast, wild rodents (mice, voles, squirrels) were colonized with a unique complement of S. aureus lineages that are widely disseminated across Europe. In order to investigate the molecular basis for S. aureus adaptation to rodent hosts, genome-wide association analysis was carried out revealing a unique complement of bacteriophages associated with a rodent host ecology. Of note, we identified novel prophages and pathogenicity islands in rodent-derived S. aureus that conferred the potential for coagulation of rodent plasma, a key phenotype of abscess formation and persistence. Our findings highlight the remarkable capacity of S. aureus to expand into new host populations, driven by the acquisition of genes promoting survival in new host-species.

Phage SEP1 hijacks Staphylococcus epidermidis stationary cells' metabolism to replicate.

In nature, bacteria often survive in a stationary state with low metabolic activity. Phages use the metabolic machinery of the host cell to replicate, and, therefore, their efficacy against non-dividing cells is usually limited. Nevertheless, it was previously shown that the Staphylococcus epidermidis phage SEP1 has the remarkable capacity to actively replicate in stationary-phase cells, reducing their numbers. Here, we studied for the first time the transcriptomic profiles of both exponential and stationary cells infected with SEP1 phage using RNA-seq to gain a better understanding of this rare phenomenon. We showed that SEP1 successfully takes over the transcriptional apparatus of both exponential and stationary cells. Infection was, however, delayed in stationary cells, with genes within the gp142-gp154 module putatively implicated in host takeover. S. epidermidis responded to SEP1 infection by upregulating three genes involved in a DNA modification system, with this being observed already 5 min after infection in exponential cells and later in stationary cells. In stationary cells, a significant number of genes involved in translation and RNA metabolic and biosynthetic processes were upregulated after 15 and 30 min of SEP1 infection in comparison with the uninfected control, showing that SEP1 activates metabolic and biosynthetic pathways necessary to its successful replication.IMPORTANCEMost phage-host interaction studies are performed with exponentially growing cells. However, this cell state is not representative of what happens in natural environments. Additionally, most phages fail to replicate in stationary cells. The Staphylococcus epidermidis phage SEP1 is one of the few phages reported to date to be able to infect stationary cells. Here, we unveiled the interaction of SEP1 with its host in both exponential and stationary states of growth at the transcriptomic level. The findings of this study provide valuable insights for a better implementation of phage therapy since phages able to infect stationary cells could be more efficient in the treatment of recalcitrant infections.

Characterisation of a SapYZU11@ZnFe2O4 biosensor reveals its mechanism for the rapid and sensitive colourimetric detection of viable Staphylococcus aureus in food matrices.

Although bacteriophage-based biosensors hold promise for detecting Staphylococcus aureus in food products in a timely, simple, and sensitive manner, the associated targeting mechanism of the biosensors remains unclear. Herein, a colourimetric biosensor SapYZU11@ZnFe2O4, based on a broad-spectrum S. aureus lytic phage SapYZU11 and a ZnFe2O4 nanozyme, was constructed, and its capacity to detect viable S. aureus in food was evaluated. Characterisation of SapYZU11@ZnFe2O4 revealed its effective immobilisation, outstanding biological activity, and peroxidase-like capability. The peroxidase activity of SapYZU11@ZnFe2O4 significantly decreased after the addition of S. aureus, potentially due to blockage of the nanozyme active sites. Moreover, SapYZU11@ZnFe2O4 can detect S. aureus from various sources and S. aureus isolates that phage SapYZU11 could not lyse. This may be facilitated by the adsorption of the special receptor-binding proteins on the phage tail fibre and wall teichoic acid receptors of S. aureus. Besides, SapYZU11@ZnFe2O4 exhibited remarkable sensitivity and specificity when employing colourimetric techniques to rapidly determine viable S. aureus counts in food samples, with a detection limit of 0.87 × 102 CFU/mL. Thus, SapYZU11@ZnFe2O4 has broad application prospects for the detection of viable S. aureus cells on food substrates.

Bacteriophage ISP eliminates Staphylococcus aureus in planktonic phase, but not in the various stages of the biofilm cycle.

Metal-implant associated bacterial infections are a major clinical problem due to antibiotic treatment failure. As an alternative, we determined the effects of bacteriophage ISP on clinical isolates of Staphylococcus aureus in various stages of its life cycle in relation to biofilm formation and maturation. ISP effectively eliminated all planktonic phase bacteria, whereas its efficacy was reduced against bacteria attached to the metal implant and bacteria embedded within biofilms. The biofilm architecture hampered the bactericidal effects of ISP, as mechanical disruption of biofilms improved the efficacy of ISP against the bacteria. Phages penetrated the biofilm and interacted with the bacteria throughout the biofilm. However, most of the biofilm-embedded bacteria were phage-tolerant. In agreement, bacteria dispersed from mature biofilms of all clinical isolates, except for LUH15394, tolerated the lytic activity of ISP. Lastly, persisters within mature biofilms tolerated ISP and proliferated in its presence. Based on these findings, we conclude that ISP eliminates planktonic phase Staphylococcus aureus while its efficacy is limited against bacteria attached to the metal implant, embedded within (persister-enriched) biofilms, and dispersed from biofilms.

Evaluation of bacteriophage ϕ11 host recognition protein and its host-binding peptides for diagnosing/targeting Staphylococcus aureus infections.

BACKGROUND: Evaluating the potential of using both synthetic and biological products as targeting agents for the diagnosis, imaging, and treatment of infections due to particularly antibiotic-resistant pathogens is important for controlling infections. This study examined the interaction between Gp45, a receptor-binding protein of the ϕ11 lysogenic phage, and its host Staphylococcus aureus (S. aureus), a common cause of nosocomial infections. METHODS: Using molecular dynamics and docking simulations, this study identified the peptides that bind to S. aureus wall teichoic acids via Gp45. It compared the binding affinity of Gp45 and the two highest-scoring peptide sequences (P1 and P3) and their scrambled forms using microscopy, spectroscopy, and ELISA. RESULTS: It was found that rGp45 (recombinant Gp45) and chemically synthesised P1 had a higher binding affinity for S. aureus compared with all other peptides, except for Escherichia coli. Furthermore, rGp45 had a capture efficiency of > 86%; P1 had a capture efficiency of > 64%. CONCLUSION: These findings suggest that receptor-binding proteins such as rGp45, which provide a critical initiation of the phage life cycle for host adsorption, might play an important role in the diagnosis, imaging, and targeting of bacterial infections. Studying such proteins could accordingly enable the development of effective strategies for controlling infections.

Phage therapy combined with Gum Karaya injectable hydrogels for treatment of methicillin-resistant Staphylococcus aureus deep wound infection in a porcine model.

Skin and soft tissue infections (SSTIs) represent a significant healthcare challenge, particularly in the context of increasing antibiotic resistance. This study investigates the efficacy of a novel therapeutic approach combining bacteriophage (phage) therapy with a gum Karaya (GK)-based hydrogel delivery system in a porcine model of deep staphylococcal SSTIs. The study exploits the lytic activity and safety of the Staphylococcus phage 812K1/420 of the Kayvirus genus, which is active against methicillin-resistant Staphylococcus aureus (MRSA). The GK injectable hydrogels and hydrogel films, developed by our research group, serve as effective, non-toxic, and easy-to-apply delivery systems, supporting moist wound healing and re-epithelialization. In the porcine model, the combined treatment showed asynergistic effect, leading to a significant reduction in bacterial load (2.5 log CFU/gram of tissue) within one week. Local signs of inflammation were significantly reduced by day 8, with clear evidence of re-epithelialization and wound contraction. Importantly, no adverse effects of the GK-based delivery system were observed throughout the study. The results highlight the potential of this innovative therapeutic approach to effectively treat deep staphylococcal SSTIs, providing a promising avenue for further research and clinical application in the field of infections caused by antibiotic-resistant bacteria.

Isolation and characterization of two Staphylococcus aureus lytic bacteriophages "Huma" and "Simurgh".

Nowadays finding the new antimicrobials is necessary due to the emerging of multidrug resistant strains. The present study aimed to isolate and characterize bacteriophages against S. aureus. Strains Huma and Simurgh were the two podovirus morphology phages which isolated and then characterized. Huma and Simurgh had a genome size of 16,853 and 17,245 bp, respectively and both were Rosenblumvirus with G + C content of 29%. No lysogeny-related genes, nor virulence genes were identified in their genomes. They were lytic only against two out of four S. aureus strains. They also were able to inhibit S. aureus for 8 h in-vitro. Both showed a rapid adsorption. Huma and Simurgh had the latent period of 80 and 60 m and the burst sizes of 45 and 40 PFU/ml and also, they showed very low cell toxicity of 1.23%-1.79% on HT-29 cells, respectively. Thus, they can be considered potential candidates for biocontrol applications.

Phage protein Gp11 blocks Staphylococcus aureus cell division by inhibiting peptidoglycan biosynthesis.

Phages and bacteria have a long history of co-evolution. However, these dynamics of phage-host interactions are still largely unknown; identification of phage inhibitors that remodel host metabolism will provide valuable information for target development for antimicrobials. Here, we perform a comprehensive screen for early-gene products of ΦNM1 that inhibit cell growth in Staphylococcus aureus. A small membrane protein, Gp11, with inhibitory effects on S. aureus cell division was identified. A bacterial two-hybrid library containing 345 essential S. aureus genes was constructed to screen for targets of Gp11, and Gp11 was found to interact with MurG and DivIC. Defects in cell growth and division caused by Gp11 were dependent on MurG and DivIC, which was further confirmed using CRISPRi hypersensitivity assay. Gp11 interacts with MurG, the protein essential for cell wall formation, by inhibiting the production of lipid II to regulate peptidoglycan (PG) biosynthesis on the cell membrane. Gp11 also interacts with cell division protein DivIC, an essential part of the division machinery necessary for septal cell wall assembly, to disrupt the recruitment of division protein FtsW. Mutations in Gp11 result in loss of its ability to cause growth defects, whereas infection with phage in which the gp11 gene has been deleted showed a significant increase in lipid II production in S. aureus. Together, our findings reveal that a phage early-gene product interacts with essential host proteins to disrupt PG biosynthesis and block S. aureus cell division, suggesting a potential pathway for the development of therapeutic approaches to treat pathogenic bacterial infections. IMPORTANCE: Understanding the interplay between phages and their hosts is important for the development of novel therapies against pathogenic bacteria. Although phages have been used to control methicillin-resistant Staphylococcus aureus infections, our knowledge related to the processes in the early stages of phage infection is still limited. Owing to the fact that most of the phage early proteins have been classified as hypothetical proteins with uncertain functions, we screened phage early-gene products that inhibit cell growth in S. aureus, and one protein, Gp11, selectively targets essential host genes to block the synthesis of the peptidoglycan component lipid II, ultimately leading to cell growth arrest in S. aureus. Our study provides a novel insight into the strategy by which Gp11 blocks essential host cellular metabolism to influence phage-host interaction. Importantly, dissecting the interactions between phages and host cells will contribute to the development of new and effective therapies to treat bacterial infections.

Biological and genomic characterization of 4 novel bacteriophages isolated from sewage or the environment using non-aureus Staphylococci strains.

Non-aureus staphylococci (NAS) are an essential group of bacteria causing antimicrobial resistant intramammary infections in livestock, particularly dairy cows. Therefore, bacteriophages emerge as a potent bactericidal agent for NAS mastitis. This study aimed to obtain NAS-specific bacteriophages using bacterial strains isolated from cows with mastitis, subsequently evaluating their morphological, genomic, and lytic characteristics. Four distinct NAS bacteriophages were recovered from sewage or the environment of Chinese dairy farms; PT1-1, PT94, and PT1-9 were isolated using Staphylococcus chromogenes and PT1-4 using Staphylococcus gallinarum. Both PT1-1 (24/54, 44 %) and PT94 (28/54, 52 %) had broader lysis than PT1-4 (3/54, 6 %) and PT1-9 (10/54, 19 %), but PT1-4 and PT1-9 achieved cross-species lysis. All bacteriophages had a short latency period and good environmental tolerance, including surviving at pH=4-10 and at 30-60℃. Except for PT1-9, all bacteriophages had excellent bactericidal efficacy within 5 h of co-culture with host bacteria in vitro at various multiplicity of infection (MOIs). Based on whole genome sequencing, average nucleotide identity (ANI) analysis of PT1-1 and PT94 can be classified as the same species, consistent with whole-genome synteny analysis. Although motifs shared by the 4 bacteriophages differed little from those of other bacteriophages, a phylogenetic tree based on functional proteins indicated their novelty. Moreover, based on whole genome comparisons, we inferred that cross-species lysis of bacteriophage may be related to the presence of "phage tail fiber." In conclusion 4 novel NAS bacteriophages were isolated; they had good biological properties and unique genomes, with potential for NAS mastitis therapy.

Bacteriophages from human skin infecting coagulase-negative Staphylococcus: diversity, novelty and host resistance.

The human skin microbiome comprises diverse populations that differ temporally between body sites and individuals. The virome is a less studied component of the skin microbiome and the study of bacteriophages is required to increase knowledge of the modulation and stability of bacterial communities. Staphylococcus species are among the most abundant colonisers of skin and are associated with both health and disease yet the bacteriophages infecting the most abundant species on skin are less well studied. Here, we report the isolation and genome sequencing of 40 bacteriophages from human skin swabs that infect coagulase-negative Staphylococcus (CoNS) species, which extends our knowledge of phage diversity. Six genetic clusters of phages were identified with two clusters representing novel phages, one of which we characterise and name Alsa phage. We identified that Alsa phages have a greater ability to infect the species S. hominis that was otherwise infected less than other CoNS species by the isolated phages, indicating an undescribed barrier to phage infection that could be in part due to numerous restriction-modification systems. The extended diversity of Staphylococcus phages here enables further research to define their contribution to skin microbiome research and the mechanisms that limit phage infection.

Isolation and characterisation of a novel Silviavirus bacteriophage promising antimicrobial agent against methicillin-resistant Staphylococcus aureus infections.

The increasing prevalence of methicillin-resistant Staphylococcus aureus (MRSA) emphasises the urgent need for novel antimicrobial agents as alternatives to antibiotics. Bacteriophage therapy is one of the most promising antimicrobial strategies. Here, we isolated and comprehensively characterized a novel Staphylococcus phage, vB_SauM_VL10 (VL10), from urban sewage. The VL10 genome displays 141,746 bp of linear double-stranded DNA, containing 193 open reading frames and lacking tRNA, virulence, or antibiotic resistance genes. Phylogenetic analysis categorizes VL10 as a novel species within the Silviavirus genus, Twortvirinae subfamily. VL10 exhibits lytic behaviour characterized by efficient adsorption, a short latent period, and substantial burst size, with environmental stability. It demonstrates lytic activity against 79.06% of tested S. aureus strains, highlighting its species specificity. Additionally, VL10 effectively targets MRSA biofilms, reducing biomass and viable cells. In MRSA-infected G. mellonella larvae, VL10 enhances survival rates, supporting its potential for phage therapy applications. Moreover, the emergence of VL10-resistant S. aureus strains associated with fitness trade-offs, including reduced growth, biofilm formation, and virulence. Altogether, these findings emphasize VL10 as a promising candidate for developing therapeutic agents against MRSA infections, providing insights into phage biology and resistance dynamics.

Bacteriophages avoid autoimmunity from cognate immune systems as an intrinsic part of their life cycles.

Dormant prophages protect lysogenic cells by expressing diverse immune systems, which must avoid targeting their cognate prophages upon activation. Here we report that multiple Staphylococcus aureus prophages encode Tha (tail-activated, HEPN (higher eukaryotes and prokaryotes nucleotide-binding) domain-containing anti-phage system), a defence system activated by structural tail proteins of incoming phages. We demonstrate the function of two Tha systems, Tha-1 and Tha-2, activated by distinct tail proteins. Interestingly, Tha systems can also block reproduction of the induced tha-positive prophages. To prevent autoimmunity after prophage induction, these systems are inhibited by the product of a small overlapping antisense gene previously believed to encode an excisionase. This genetic organization, conserved in S. aureus prophages, allows Tha systems to protect prophages and their bacterial hosts against phage predation and to be turned off during prophage induction, balancing immunity and autoimmunity. Our results show that the fine regulation of these processes is essential for the correct development of prophages' life cycle.

Wall teichoic acid substitution with glucose governs phage susceptibility of Staphylococcus epidermidis.

The species- and clone-specific susceptibility of Staphylococcus cells for bacteriophages is governed by the structures and glycosylation patterns of wall teichoic acid (WTA) glycopolymers. The glycosylation-dependent phage-WTA interactions in the opportunistic pathogen Staphylococcus epidermidis and in other coagulase-negative staphylococci (CoNS) have remained unknown. We report a new S. epidermidis WTA glycosyltransferase TagE whose deletion confers resistance to siphoviruses such as ΦE72 but enables binding of otherwise unbound podoviruses. S. epidermidis glycerolphosphate WTA was found to be modified with glucose in a tagE-dependent manner. TagE is encoded together with the enzymes PgcA and GtaB providing uridine diphosphate-activated glucose. ΦE72 transduced several other CoNS species encoding TagE homologs, suggesting that WTA glycosylation via TagE is a frequent trait among CoNS that permits interspecies horizontal gene transfer. Our study unravels a crucial mechanism of phage-Staphylococcus interaction and horizontal gene transfer, and it will help in the design of anti-staphylococcal phage therapies.IMPORTANCEPhages are highly specific for certain bacterial hosts, and some can transduce DNA even across species boundaries. How phages recognize cognate host cells remains incompletely understood. Phages infecting members of the genus Staphylococcus bind to wall teichoic acid (WTA) glycopolymers with highly variable structures and glycosylation patterns. How WTA is glycosylated in the opportunistic pathogen Staphylococcus epidermidis and in other coagulase-negative staphylococci (CoNS) species has remained unknown. We describe that S. epidermidis glycosylates its WTA backbone with glucose, and we identify a cluster of three genes responsible for glucose activation and transfer to WTA. Their inactivation strongly alters phage susceptibility patterns, yielding resistance to siphoviruses but susceptibility to podoviruses. Many different CoNS species with related glycosylation genes can exchange DNA via siphovirus ΦE72, suggesting that glucose-modified WTA is crucial for interspecies horizontal gene transfer. Our finding will help to develop antibacterial phage therapies and unravel routes of genetic exchange.

Injectable Phage-Loaded Microparticles Effectively Release Phages to Kill Methicillin-Resistant Staphylococcus aureus.

The increasing prevalence of bacterial multidrug antibiotic resistance has led to a serious threat to public health, emphasizing the urgent need for alternative antibacterial therapeutics. Lytic phages, a class of viruses that selectively infect and kill bacteria, offer promising potential as alternatives to antibiotics. However, injectable carriers with a desired release profile remain to be developed to deliver them to infection sites. To address this challenge, phage-loaded microparticles (Phage-MPs) have been developed to deliver phages to the infection site and release phages for an optimal therapeutic effect. The Phage-MPs are synthesized by allowing phages to be electrostatically attached onto the porous polyethylenimine-modified silk fibroin microparticles (SF-MPs). The high specific surface area of SF-MPs allows them to efficiently load phages, reaching about 1.25 × 1010 pfu per mg of microparticles. The Phage-MPs could release phages in a controlled manner to achieve potent antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA). Unlike the diffuse biodistribution of free phages post-intraperitoneal injection, Phage-MPs could continuously release phages to effectively boost the local phage concentration at the bacterial infection site after they are intraperitoneally injected into an abdominal MRSA-infected mouse model. In a mouse abdominal MRSA infection model, Phage-MPs significantly reduce the bacterial load in major organs, achieving an efficient therapeutic effect. Furthermore, Phage-MPs demonstrate outstanding biocompatibility both in vitro and in vivo. Overall, our research lays the foundation for a new generation of phage-based therapies to combat antibiotic-resistant bacterial infections.

LysSYL: a broad-spectrum phage endolysin targeting Staphylococcus species and eradicating S. aureus biofilms.

BACKGROUND: Staphylococcus aureus and its single or mixed biofilm infections seriously threaten global public health. Phage therapy, which uses active phage particles or phage-derived endolysins, has emerged as a promising alternative strategy to antibiotic treatment. However, high-efficient phage therapeutic regimens have yet to be established. RESULTS: In this study, we used an enrichment procedure to isolate phages against methicillin-resistant S. aureus (MRSA) XN108. We characterized phage SYL, a new member of the Kayvirus genus, Herelleviridae family. The phage endolysin LysSYL was expressed. LysSYL demonstrated stability under various conditions and exhibited a broader range of efficacy against staphylococcal strains than its parent phage (100% vs. 41.7%). Moreover, dynamic live/dead bacterial observation demonstrated that LysSYL could completely lyse MRSA USA300 within 10 min. Scan and transmission electron microscopy revealed evident bacterial cell perforation and deformation. In addition, LysSYL displayed strong eradication activity against single- and mixed-species biofilms associated with S. aureus. It also had the ability to kill bacterial persisters, and proved highly effective in eliminating persistent S. aureus when combined with vancomycin. Furthermore, LysSYL protected BALB/c mice from lethal S. aureus infections. A single-dose treatment with 50 mg/kg of LysSYL resulted in a dramatic reduction in bacterial loads in the blood, liver, spleen, lungs, and kidneys of a peritonitis mouse model, which resulted in rescuing 100% of mice challenged with 108 colony forming units of S. aureus USA300. CONCLUSIONS: Overall, the data provided in this study highlight the strong therapeutic potential of endolysin LysSYL in combating staphylococcal infections, including mono- and mixed-species biofilms related to S. aureus.

Nanozyme colourimetry based on temperate bacteriophage for rapid and sensitive detection of Staphylococcus aureus in food matrices.

Although bacteriophage-based biosensors are promising tools for rapid, convenient, and sensitive detection of Staphylococcus aureus in food products, the effect of biosensors using temperate phages as biorecognition elements to detect viable S. aureus isolates remains unclear. In this study, three temperate S. aureus phages were isolated and their biological features (one-step growth, host range, pH stability, temperature stability, and adsorption rate) were evaluated as the biological element. The selected phage SapYZUs8 was immobilized on the nanozyme Cu-MOF via electrostatic interactions to generate SapYZUs8@Cu-MOF, and its detection performance in real food (skim milk and pork) was then evaluated. Compared with phages SapYZUm7 and SapYZUs16, phage SapYZUs8 exhibited a broader host range, greater pH stability (3-12), and a better absorption rate (92 %, 8 min) suitable for S. aureus detection, which is likely the result of the DNA replication (DNA helicase) and phage tail protein genes in the SapYZUs8 genome. Therefore, phage SapYZUs8 was fixed on Cu-MOF to generate SapYZUs8@Cu-MOF, which exhibited good sensitivity and specificity for rapid colourimetric detection of viable S. aureus. The method took <0.5 h, and the detection limit was 1.09 × 102 CFU/mL. In addition, SapYZUs8@Cu-MOF was successfully employed for the colourimetric detection of S. aureus in food samples without interference from different food additives, NaCl concentrations, or pH values. With these benefits, it allows rapid visual assessment of S. aureus levels.

Bacteriophage therapy for drug-resistant Staphylococcus aureus infections.

Drug-resistant Staphylococcus aureus stands as a prominent pathogen in nosocomial and community-acquired infections, capable of inciting various infections at different sites in patients. This includes Staphylococcus aureus bacteremia (SaB), which exhibits a severe infection frequently associated with significant mortality rate of approximately 25%. In the absence of better alternative therapies, antibiotics is still the main approach for treating infections. However, excessive use of antibiotics has, in turn, led to an increase in antimicrobial resistance. Hence, it is imperative that new strategies are developed to control drug-resistant S. aureus infections. Bacteriophages are viruses with the ability to infect bacteria. Bacteriophages, were used to treat bacterial infections before the advent of antibiotics, but were subsequently replaced by antibiotics due to limited theoretical understanding and inefficient preparation processes at the time. Recently, phages have attracted the attention of many researchers again because of the serious problem of antibiotic resistance. This article provides a comprehensive overview of phage biology, animal models, diverse clinical case treatments, and clinical trials in the context of drug-resistant S. aureus phage therapy. It also assesses the strengths and limitations of phage therapy and outlines the future prospects and research directions. This review is expected to offer valuable insights for researchers engaged in phage-based treatments for drug-resistant S. aureus infections.

Phage susceptibility determinants of the opportunistic pathogen Staphylococcus epidermidis.

Staphylococcus epidermidis is a common member of the human skin and nose microbiomes and a frequent cause of invasive infections. Transducing phages accomplish the horizontal transfer of resistance and virulence genes by mispackaging of mobile-genetic elements, contributing to severe, therapy-refractory S. epidermidis infections. Lytic phages on the other hand can be interesting candidates for new anti-S. epidermidis phage therapies. Despite the importance of phages, we are only beginning to unravel S. epidermidis phage interactions. Recent studies shed new light on S. epidermidis phage diversity, host range, and receptor specificities. Modulation of cell wall teichoic acids, the major phage receptor structures, along with other phage defense mechanisms, are crucial determinants for S. epidermidis susceptibility to different phage groups.

The stability of Staphylococcal bacteriophage in presence of local vancomycin concentrations used in clinical practice.

PURPOSE: To evaluate the stability of a clinically used Staphylococcal bacteriophage with doses of vancomycin that are encountered with local administration of vancomycin for musculoskeletal infections. METHODS: A Staphylococcal bacteriophage was evaluated for stability in different pH ranges. Then that same bacteriophage was evaluated for stability with different concentrations of vancomycin and with vancomycin biodegradable antibiotic beads. RESULTS: The bacteriophage had stability within a pH range of 4-10. There was a statistically significant (P < 0.05) decrease in the amount of bacteriophage over 24 h for vancomycin concentrations of 10 mg/mL and 100 mg/mL compared to lower vancomycin concentrations (1 mg/mL, 0.1 mg/mL and normal saline). However, no statistically significant decrease in the amount of bacteriophage was seen with biodegradable vancomycin beads over 24 h. CONCLUSION: These findings have important clinical ramifications in that they show local administration of bacteriophages with concomitant local vancomycin powder therapy should be avoided. Moreover, these findings should spearhead further research into bacteriophage stability in in vivo environments.