Current review-The rise of bacteriophage as a unique therapeutic platform in treating peri-prosthetic joint infections

Do bacteriophages have activity in synovial fluid and against synovial fluid induced bacterial aggregates?

Bacteriophage therapy is a promising adjuvant therapy for the treatment of periprosthetic joint infections. However, there is a paucity of knowledge about the activity of bacteriophages in synovial fluid. Therefore, this study evaluated the activity of a clinically used bacteriophage in synovial fluid as well as the ability of that bacteriophage to prevent the formation of and eradicate bacteria in synovial fluid induced aggregates. The results of this study reinforce that synovial fluid induced aggregates form rapidly in numerous synovial fluid concentrations. More importantly, there was a statistically significant reduction in bacteriophage activity in synovial fluid compared to tryptic soy broth (p < 0.05) and the bacteriophage could not prevent the formation synovial fluid induced aggregates. Also the bacteriophage could not significantly reduce the amount of bacteria in the synovial fluid induced aggregates when compared to controls, and this was not secondary to resistance. Rather the reduced activity seems to be caused by bacteriophages being hindered in the ability to attach to bacterial receptors. We hypothesize this occurred because the viscosity of synovial fluid slowed bacteriophage interactions with planktonic bacteria and the synovial fluid polymers obstructed the bacteriophage attachment receptors thereby preventing attachment to bacteria in the aggregates. These findings have clinical ramifications, supporting the use of bacteriophage therapy as an adjunct to surgical interventions and not in isolation, at the nascent stage. While these findings show a shortcoming of bacteriophage therapy in periprosthetic joint infections, the knowledge gained should spearhead further research to ultimately devise effective and reproducible bacteriophage therapeutics.

Current treatments for biofilm-associated periprosthetic joint infection and new potential strategies

Periprosthetic joint infection (PJI) remains a devastating complication after total joint arthroplasty. Bacteria involved in these infections are notorious for adhering to foreign implanted surfaces and generating a biofilm matrix. These biofilms protect the bacteria from antibiotic treatment and the immune system making eradication difficult. Current treatment strategies including debridement, antibiotics, and implant retention, and one- and two-stage revisions still present a relatively high overall failure rate. One of the main shortcomings that has been associated with this high failure rate is the lack of a robust approach to treating bacterial biofilm. Therefore, in this review, we will highlight new strategies that have the potential to combat PJI by targeting biofilm integrity, therefore giving antibiotics and the immune system access to the internal network of the biofilm structure. This combination antibiofilm/antibiotic therapy may be a new strategy for PJI treatment while promoting implant retention.

Mini Review Therapeutic Strategies Targeting for Biofilm and Bone Infections

Bone infection results in a complex inflammatory response and bone destruction. A broad spectrum of bacterial species has been involved for jaw osteomyelitis, hematogenous osteomyelitis, vertebral osteomyelitis or diabetes mellitus, such as Staphylococcus aureus (S. aureus), coagulase-negative Staphylococcus species, and aerobic gram-negative bacilli. S. aureus is the major pathogenic bacterium for osteomyelitis, which results in a complex inflammatory response and bone destruction. Although various antibiotics have been applied for bone infection, the emergence of drug resistance and biofilm formation significantly decrease the effectiveness of those agents. In combination with gram-positive aerobes, gram-negative aerobes and anaerobes functionally equivalent pathogroups interact synergistically, developing as pathogenic biofilms and causing recurrent infections. The adhesion of biofilms to bone promotes bone destruction and protects bacteria from antimicrobial agent stress and host immune system infiltration. Moreover, bone is characterized by low permeability and reduced blood flow, further hindering the therapeutic effect for bone infections. To minimize systemic toxicity and enhance antibacterial effectiveness, therapeutic strategies targeting on biofilm and bone infection can serve as a promising modality. Herein, we focus on biofilm and bone infection eradication with targeting therapeutic strategies. We summarize recent targeting moieties on biofilm and bone infection with peptide-, nucleic acid-, bacteriophage-, CaP- and turnover homeostasis-based strategies. The antibacterial and antibiofilm mechanisms of those therapeutic strategies include increasing antibacterial agents’ accumulation by bone specific affinity, specific recognition of phage-bacteria, inhibition biofilm formation in transcription level. As chronic inflammation induced by infection can trigger osteoclast activation and inhibit osteoblast functioning, we additionally expand the potential applications of turnover homeostasis-based therapeutic strategies on biofilm or infection related immunity homeostasis for host-bacteria. Based on this review, we expect to provide useful insights of targeting therapeutic efficacy for biofilm and bone infection eradication.

How Good are Bacteriophages as an Alternative Therapy to Mitigate Biofilms of Nosocomial Infections

Bacteria survive on any surface through the generation of biofilms that provide a protective environment to grow as well as making them drug resistant. Extracellular polymeric matrix is a crucial component in biofilm formation. The presence of biofilms consisting of common opportunistic and nosocomial, drug-resistant pathogens has been reported on medical devices like catheters and prosthetics, leading to many complications. Several approaches are under investigation to combat drug-resistant bacteria. Deployment of bacteriophages is one of the promising approaches to invade biofilm that may expose bacteria to the conditions adverse for their growth. Penetration into these biofilms and their destruction by bacteriophages is brought about due to their small size and ability of their progeny to diffuse through the bacterial cell wall. The other mechanisms employed by phages to infect biofilms may include their relocation through water channels to embedded host cells, replication at local sites followed by infection to the neighboring cells and production of depolymerizing enzymes to decompose viscous biofilm matrix, etc. Various research groups are investigating intricacies involved in phage therapy to mitigate the bacterial infection and biofilm formation. Thus, bacteriophages represent a good control over different biofilms and further understanding of phage-biofilm interaction at molecular level may overcome the clinical challenges in phage therapy. The present review summarizes the comprehensive details on dynamic interaction of phages with bacterial biofilms and the role of phage-derived enzymes - endolysin and depolymerases in extenuating biofilms of clinical and medical concern. The methodology employed was an extensive literature search, using several keywords in important scientific databases, such as Scopus, Web of Science, PubMed, ScienceDirect, etc. The keywords were also used with Boolean operator "And". More than 250 relevant and recent articles were selected and reviewed to discuss the evidence-based data on the application of phage therapy with recent updates, and related potential challenges.

Combination of pre-adapted bacteriophage therapy and antibiotics for treatment of fracture-related infection due to pandrug-resistant Klebsiella pneumoniae

A 30-year-old bombing victim with a fracture-related pandrug-resistant Klebsiella pneumoniae infection after long-term (>700 days) antibiotic therapy is treated with a pre-adapted bacteriophage along with meropenem and colistin, followed by ceftazidime/avibactam. This salvage therapy results in objective clinical, microbiological and radiological improvement of the patient’s wounds and overall condition. In support, the bacteriophage and antibiotic combination is highly effective against the patient’s K. pneumoniae strain in vitro, in 7-day mature biofilms and in suspensions.

In this case study of a patient with fracture-related pandrug-resistant Klebsiella pneumoniae infection after long-term antibiotic therapy, the authors use a combination therapy of pre-adapted bacteriophage and antibiotics resulting in clinical, microbiological and radiological improvement.

Phage Activity against Planktonic and Biofilm Staphylococcus aureus Periprosthetic Joint Infection Isolates

We recently reported the successful treatment of a case of periprosthetic joint infection (PJI) with phage. Phage activity against bacteria causing PJI has not been systematically evaluated. Here, we examined the in vitro activity of seven phages against 122 clinical isolates of Staphylococcus aureus recovered between April 1999 and February 2018 from subjects with PJI. Phages were assessed against planktonic and biofilm phenotypes. Activity of individual phages was demonstrated against up to 73% of bacterial isolates in the planktonic state and up to 100% of biofilms formed by isolates that were planktonically phage susceptible. Susceptibility to phage was not correlated with small-colony-variant phenotype for planktonic or biofilm bacteria; correlation between antibiotic susceptibility and planktonic phage susceptibility and between biofilm phage susceptibility and strength of biofilm formation were noted under select conditions. These results demonstrate that phages can infect S. aureus causing PJI in both planktonic and biofilm phenotypes, and thus are worthy of investigation as an alternative or addition to antibiotics in this setting.

A systematic review of phage therapy applied to bone and joint infections: an analysis of success rates, treatment modalities and safety

Bone and joint infections are difficult to treat, and increasing antibiotic resistance has only made them more challenging. This has led to renewed interest in phage therapy (PT). The aim of this systematic review was to determine success rate, current treatment modalities and safety of PT in bone and joint infections.A systematic search of PubMed, EMBASE and Cochrane databases as well as the journal PHAGE for literature published between January 2000 and April 2021 was conducted according to PRISMA guidelines to identify all human studies assessing bacteriophages as therapy for bone and joint infections. All study designs and patient populations were eligible. The review's primary outcome was success rate.Twenty records describing a total of 51 patients and 52 treatment episodes were included. No randomized controlled studies were identified. The overall success rate was 71% (n = 37/52). Topical administration alone was the most frequent administration route (85%, n = 44/52). Antibiotics were administered concomitantly with PT in the majority of treatments (79%, n = 41/52), and surgery was performed for 87% (n = 45/52) of treatment episodes. Four minor adverse events related to PT were reported, representing 8% (n = 4/52) of treatment episodes.PT for bone and joint infections has not been evaluated in any randomized controlled clinical study, and current administration modalities are highly variable between case reports and case series. While publications included here show potential benefit and few adverse effects, clinical trials are warranted to assess the efficacy of PT for bone and joint infections and determine optimal treatment modalities. Cite this article: EFORT Open Rev 2021;6:1148-1156. DOI: 10.1302/2058-5241.6.210073.

[Treatment of bone and periprosthetic infections with bacteriophages : A systematic review]

Hintergrund

Die Behandlung von Knochen- und Protheseninfektionen bleibt trotz moderner Behandlungskonzepte mit interdisziplinärem Therapieansatz schwierig und weitere Maßnahmen zur Verbesserung des Behandlungsergebnisses sind wünschenswert. Präklinischen Studien liefern ein vielversprechendes Bild der Wirksamkeit von Bakteriophagen zur Behandlung von Knochen- und Protheseninfektionen.

Ziel der Arbeit

Die vorliegende Arbeit gibt eine systematische Übersicht über die klinische Anwendung von Bakteriophagen zur Behandlung von Knochen- und Protheseninfektionen.

Material und Methoden

Eine systematische Suche wurde in PubMed zur Identifikation von primären klinischen Daten zur Anwendung der Phagentherapie bei Patienten mit Knochen- und Protheseninfektion durchgeführt.

Ergebnisse

Elf Studien wurden eingeschlossen, bestehend aus 8 Fallberichten und 3 Fallserien. Indikationen der Phagentherapie waren periprothetische Infektionen (n = 12, 52,2 %), frakturassoziierte Infektionen (n = 9, 39,1 %), Osteomyelitis (n = 1, 4,4 %) und eine Iliosakralgelenkinfektion nach Zementaugmentation einer Metastase (n = 1, 4,4 %). Die Interventionen waren heterogen, Phagen wurden intravenös verabreicht, intraoperativ ins Gelenk injiziert, intraoperativ lokal angewendet oder über Drainagen appliziert. In Kombination mit Antibiotikatherapie konnte eine vollständige Infekteradikation bei 18 Patienten (78,3 %) erreicht werden. Bei 91,3 % der Patienten wurden keine Nebenwirkungen berichtet.

Schlussfolgerung

Bakteriophagen sind eine vielversprechende Behandlungsmethode von Knochen- und Protheseninfektionen in Kombination mit einer Antibiotikatherapie. Zukünftige klinische Studien mit höherem Evidenzgrad werden benötigt, um eine erfolgreiche Translation der Bakteriophagentherapie in die klinische Praxis weiter zu etablieren.

Biomaterials and technologies in the management of periprosthetic infection after total hip arthroplasty: An updated review

Although total hip arthroplasty (THA) is considered one of the most efficacious procedures for managing various hip conditions, failures due to different mechanisms are still being reported. Periprosthetic joint infection (PJI) is one of the devastating causes of failure and revision of THA. PJI carries a burden on the patient, the surgeon, and the health-care system. The diagnosis and management of PJIs carry many morbidities and increased treatment costs. The development of PJI is multifactorial, including issues related to the patient’s general condition, the surgeon’s efficiency, surgical technique, and the implants used. Recent advances in the area of diagnosis and predicting PJI as well as introducing new technologies and biomaterials update for the prevention and treatment of PJI. Local implant coatings, advancement in the bearing surfaces technologies, and new technologies such as immunotherapy and bacteriophage therapy were introduced and suggested as contemporary PJI eradication solutions. In this review, we aimed at discussing some of the newly introduced materials and technologies for the sake of PJI control.

Clinical Pharmacology of Bacteriophage Therapy: A Focus on Multidrug-Resistant Pseudomonas aeruginosa Infections

Pseudomonas aeruginosa is one of the most common causes of healthcare-associated diseases and is among the top three priority pathogens listed by the World Health Organization (WHO). This Gram-negative pathogen is especially difficult to eradicate because it displays high intrinsic and acquired resistance to many antibiotics. In addition, growing concerns regarding the scarcity of antibiotics against multidrug-resistant (MDR) and extensively drug-resistant (XDR) P. aeruginosa infections necessitate alternative therapies. Bacteriophages, or phages, are viruses that target and infect bacterial cells, and they represent a promising candidate for combatting MDR infections. The aim of this review was to highlight the clinical pharmacology considerations of phage therapy, such as pharmacokinetics, formulation, and dosing, while addressing several challenges associated with phage therapeutics for MDR P. aeruginosa infections. Further studies assessing phage pharmacokinetics and pharmacodynamics will help to guide interested clinicians and phage researchers towards greater success with phage therapy for MDR P. aeruginosa infections.

Bacteriophage therapy for bone and joint infections

Antibiotic resistance represents a threat to human health. It has been suggested that by 2050, antibiotic-resistant infections could cause ten million deaths each year. In orthopaedics, many patients undergoing surgery suffer from complications resulting from implant-associated infection. In these circumstances secondary surgery is usually required and chronic and/or relapsing disease may ensue. The development of effective treatments for antibiotic-resistant infections is needed. Recent evidence shows that bacteriophage (phages; viruses that infect bacteria) therapy may represent a viable and successful solution. In this review, a brief description of bone and joint infection and the nature of bacteriophages is presented, as well as a summary of our current knowledge on the use of bacteriophages in the treatment of bacterial infections. We present contemporary published in vitro and in vivo data as well as data from clinical trials, as they relate to bone and joint infections. We discuss the potential use of bacteriophage therapy in orthopaedic infections. This area of research is beginning to reveal successful results, but mostly in nonorthopaedic fields. We believe that bacteriophage therapy has potential therapeutic value for implant-associated infections in orthopaedics. Cite this article: Bone Joint J 2021;103-B(2):234-244.

Future directions of postoperative spinal implant infections

This article outlines some promising future concepts against postoperative spinal implant infections on the basis of today available literature. The ever-adapting bacteria causing this common complication compel a corresponding continuous research about best effective treatment. The aim is to give a perspective on several future attack-points: surgical infection prevention strategies such as technical optimization of implants and surgical technique; faster diagnostic tools to detect infection, especially in the context of late infections with low-virulent germs and with regard to decision-making in the course of the surgical workflow; and combined surgical and medical treatment options against implant infections. The surgical treatment section will also state open issues concerning implant removal, and the medical treatment section will give an outlook to promising medical alternatives in a post-antibiotic era. To keep up in this field will be important to retain spine surgery in the future as the state-of-the-art treatment option for mandatory spinal interventions in the presence of tumor or trauma and even more so as an attractive option for patients with degenerative spinal disorder for improvement of their life quality.

Bacteriophages and Lysins as Possible Alternatives to Treat Antibiotic-Resistant Urinary Tract Infections

Urinary tract infections represent a major public health problem as the rapid emergence of antibiotic-resistant strains among uropathogens is causing the failure of many current treatments. The use of bacteriophages (phages) and their derivatives to combat infectious diseases is an old approach that has been forgotten by the West for a long time, mostly due to the discovery and great success of antibiotics. In the present so-called “post-antibiotic era”, many researchers are turning their attention to the re-discovered phage therapy, as an effective alternative to antibiotics. Phage therapy includes the use of natural or engineered phages, as well as their purified lytic enzymes to destroy pathogenic strains. Many in vitro and in vivo studies have been conducted, and these have proved the great potential for this therapy against uropathogenic bacteria. Nevertheless, to date, the lack of appropriate clinical trials has hindered its widespread clinic application.

New developments and future challenges in prevention, diagnosis, and treatment of prosthetic joint infection

Prosthetic joint infection (PJI) is a devastating complication that results in substantial costs to society and patient morbidity. Advancements in our knowledge of this condition have focused on prevention, diagnosis, and treatment, in order to reduce rates of PJI and improve patient outcomes. Preventive measures such as optimization of patient comorbidities, and perioperative antibiotic usage are intensive areas of current clinical research to reduce the rate of PJI. Improved diagnostic tests such as synovial fluid (SF) α-defensin enzyme-linked immunosorbent assay, and nucleic acid-based tests for serum, SF, and tissue cultures, have improved diagnostic accuracy and organism identification. Increasing the diversity of available antibiotic therapy, immunotherapy, and alternative implant coatings remain promising treatments to improve infection eradication in the setting of PJI.

Bacteriophages and Lysins in Biofilm Control

To formulate the optimal strategy of combatting bacterial biofilms, in this review we update current knowledge on the growing problem of biofilm formation and its resistance to antibiotics which has spurred the search for new strategies to deal with this complication. Based on recent findings, the role of bacteriophages in the prevention and elimination of biofilm-related infections has been emphasized. In vitro, ex vivo and in vivo biofilm treatment models with single bacteriophages or phage cocktails have been compared. A combined use of bacteriophages with antibiotics in vitro or in vivo confirms earlier reports of the synergistic effect of these agents in improving biofilm removal. Furthermore, studies on the application of phage-derived lysins in vitro, ex vivo or in vivo against biofilm-related infections are encouraging. The strategy of combined use of phage and antibiotics seems to be different from using lysins and antibiotics. These findings suggest that phages and lysins alone or in combination with antibiotics may be an efficient weapon against biofilm formation in vivo and ex vivo, which could be useful in formulating novel strategies to combat bacterial infections. Those findings proved to be relevant in the prevention and destruction of biofilms occurring during urinary tract infections, orthopedic implant-related infections, periodontal and peri-implant infections. In conclusion, it appears that most efficient strategy of eliminating biofilms involves phages or lysins in combination with antibiotics, but the optimal scheme of their administration requires further studies.

Evaluation of the Activity of a Combination of Three Bacteriophages Alone or in Association with Antibiotics on Staphylococcus aureus Embedded in Biofilm or Internalized in Osteoblasts

Staphylococcus aureus is responsible for difficult-to-treat bone and joint infections (BJIs). This is related to its ability to form biofilm and to be internalized and persist inside osteoblasts. Recently, bacteriophage therapy has emerged as a promising option to improve treatment of such infections, but data on its activity against the specific bacterial lifestyles presented above remain scarce. We evaluated the activity of a combination of three bacteriophages, recently used for compassionate treatment in France, against S. aureus HG001 in a model of staphylococcal biofilm and a model of osteoblasts infection, alone or in association with vancomycin or rifampin. The activity of bacteriophages against biofilm-embedded S. aureus was dose dependent. In addition, synergistic effects were observed when bacteriophages were combined with antibiotics used at the lowest concentrations. Phage penetration into osteoblasts was observed only when the cells were infected, suggesting a S. aureus-dependent Trojan horse mechanism for internalization. The intracellular bacterial count of bacteria in infected osteoblasts treated with bacteriophages as well as with vancomycin was significantly higher than in cells treated with lysostaphin, used as a control condition, owing to the absence of intracellular activity and the rapid killing of bacteria released after the death of infected cells. These results suggest that bacteriophages are both inactive in the intracellular compartment after being internalized in infected osteoblasts and present a delayed killing effect on bacteria released after cell lysis into the extracellular compartment, which avoids preventing them from infecting other osteoblasts. The combination of bacteriophages tested was highly active against S. aureus embedded in biofilm but showed no activity against intracellular bacteria in the cell model used.

Effects of powdered rifampin and vancomycin solutions on biofilm production of staphylococcus aureus on orthopedic implants

PURPOSE

Hardware infections in orthopedic surgery, specifically those involving biofilm producing bacteria, are troublesome and are highly resistant to systemic antibiotics. The purpose of this study was to demonstrate the power of rifampin and vancomycin solutions in inhibiting as well as eliminating in vitro on staphylococcus aureus (S. aureus) biofilm in vitro on stainless-steel implants.

METHODS

A suspension of either S. aureus or a S. aureus containing a plasmid that cods for the green fluorescence protein containing fluorescent protein plasmid was applied to 1 × 1cm sterile stainless steel orthopedic plating material (coupon). Biofilm development was confirmed by; the quantitative assay (colony forming unit [CFU/coupon]) and visualized using confocal laser scanning microscopy. With this established method of biofilm development, we determined the minimum biofilm inhibitory concentration (MBIC) and the minimum biofilm eradication concertation (MBEC) of Rifampicin and Vancomycin. To determine the MBIC, stainless steel plates were subjected to different concentrations of antibiotic solution and inoculated with overnight cultures of S. aureus. After 24 h of incubation at 37 °C, the biofilms on the untreated and antibiotic-treated coupons were quantified. To determine the MBEC, partial S. aureus biofilms were developed on the coupons and then treated with the different concentrations of each antibiotic for 24 h. The number of bacteria within the control untreated as well as treated coupons was determined.

RESULTS

Both rifampin and vancomycin solutions inhibited biofilm production of S. aureus on stainless steel mediums; the MBIC for rifampin and vancomycin were 80 ng/mL and 1 μg/mL respectively. The MBEC for Rifampicin was similar to the MBIC. However, the MBEC for Vancomycin was 6 mg/ml.

CONCLUSIONS

When applied to orthopedic stainless steel hardware in vitro, solutions of rifampin and vancomycin powder separately or in combination can completely prevent and eliminate biofilm produced by S. aureus.

LEVEL OF EVIDENCE

II.

Evaluation of bacteriophage as an adjunct therapy for treatment of peri-prosthetic joint infection caused by Staphylococcus aureus

Phage therapy offers a potential alternate strategy for the treatment of peri-prosthetic joint infection (PJI), particularly where limited effective antibiotics are available. We undertook preclinical trials to investigate the therapeutic efficacy of a phage cocktail, alone and in combination with vancomycin, to reduce bacterial numbers within the infected joint using a clinically-relevant model of Staphylococcus aureus-induced PJI. Infected animals were randomised to 4 treatment groups, with treatment commencing 21-days post-surgery: bacteriophage alone, vancomycin alone, bacteriophage and vancomycin, and sham. At day 28 post-surgery, animals were euthanised for microbiological and immunological assessment of implanted joints. Treatment with phage alone or vancomycin alone, led to 5-fold and 6.2-fold reductions, respectively in bacterial load within peri-implant tissue compared to sham-treated animals. Compared to sham-treated animals, a 22.5-fold reduction in S. aureus burden was observed within joint tissue of animals that were administered phage in combination with vancomycin, corresponding with decreased swelling in the implanted knee. Microbiological data were supported by evidence of decreased inflammation within the joints of animals administered phage in combination with vancomycin, compared to sham-treated animals. Our findings provide further support for phage therapy as a tolerable and effective adjunct treatment for PJI.

Bacteriophages as Adjuvant to Antibiotics for the Treatment of Periprosthetic Joint Infection Caused by Multidrug-Resistant Pseudomonas aeruginosa

We documented the adjunctive bacteriophage therapy to treat a chronic relapsing periprosthetic joint infection of the knee and chronic osteomyelitis of the femur caused by multidrug-resistant Pseudomonas aeruginosa The combined antibiotic-phage treatment eradicated the infection, and no side effects to phages were observed.

Effects of isosorbide mononitrate loaded nanoparticles conjugated with anti-Staphylococcus aureus α-toxin on Staphylococcus aureus biofilms

Staphylococcus aureus (S. aureus) is associated with recalcitrant chronic infection, especially in chronic rhinosinusitis (CRS). S. aureus infection and biofilms cause poorer postsurgical outcomes. We developed isosorbide mononitrate (ISMN) loaded nanoparticles conjugated with an anti-Staphylococcus aureus alpha-toxin (anti-S. aureus α-toxin) antibody that could target biofilms and investigated their anti-biofilm effect. Anti-S. aureus α-toxin antibody coupled immunoliposomes were generated. The effect of ISMN immunoliposomes on S. aureus biofilm formation and their anti-biofilm efficacy were examined using the crystal violet method and confocal laser scanning microscopy, respectively. Relative biofilm viability at 24 h was tested using the alamarBlue assay. The biofilm formation inhibitory effect on all concentrations of ISMN immunoliposomes was stronger than that of ISMN liposomes and free ISMN (P<0.05). At concentrations of 45 and 23 mg/ml, the inhibitory effect of ISMN liposomes was stronger than that of free ISMN (P<0.05), while at 11 mg/ml, the inhibitory effect of ISMN liposomes was the same as that of ISMN (P>0.05). At 45 and 23 mg/ml, the inhibitory effect of ISMN immunoliposomes on formed biofilms was greater than that of ISMN liposomes and free ISMN (P<0.05) and the inhibitory effect of ISMN liposomes was stronger than that of free ISMN (P<0.05). At 11 mg/ml, ISMN immunoliposomes, ISMN liposomes, and ISMN had the same effect on formed biofilms (P>0.05). In conclusion, ISMN immunoliposomes nearly completely destroy biofilm structure. ISMN immunoliposomes provide a promising approach for treating infectious diseases caused by S. aureus biofilms, including refractory CRS, chronic skin infection, sepsis, and osteomyelitis.

Biological challenges of phage therapy and proposed solutions: a literature review

Introduction: In light of the emergence of antibiotic-resistant bacteria, phage (bacteriophage) therapy has been recognized as a potential alternative or addition to antibiotics in Western medicine for use in humans.Areas covered: This review assessed the scientific literature on phage therapy published between 1 January 2007 and 21 October 2019, with a focus on the successes and challenges of this prospective therapeutic.Expert opinion: Efficacy has been shown in animal models and experimental findings suggest promise for the safety of human phagotherapy. Significant challenges remain to be addressed prior to the standardization of phage therapy in the West, including the development of phage-resistant bacteria; the pharmacokinetic complexities of phage; and any potential human immune response incited by phagotherapy.

Bacteriophage Application for Difficult-to-treat Musculoskeletal Infections: Development of a Standardized Multidisciplinary Treatment Protocol

Bacteriophage therapy has recently attracted increased interest, particularly in difficult-to-treat infections. Although it is not a novel concept, standardized treatment guidelines are currently lacking. We present the first steps towards the establishment of a "multidisciplinary phage task force" (MPTF) and a standardized treatment pathway, based on our experience of four patients with severe musculoskeletal infections. After review of their medical history and current clinical status, a multidisciplinary team found four patients with musculoskeletal infections eligible for bacteriophage therapy within the scope of Article 37 of the Declaration of Helsinki. Treatment protocols were set up in collaboration with phage scientists and specialists. Based on the isolated pathogens, phage cocktails were selected and applied intraoperatively. A draining system allowed postoperative administration for a maximum of 10 days, 3 times per day. All patients received concomitant antibiotics and their clinical status was followed daily during phage therapy. No severe side-effects related to the phage application protocol were noted. After a single course of phage therapy with concomitant antibiotics, no recurrence of infection with the causative strains occurred, with follow-up periods ranging from 8 to 16 months. This study presents the successful outcome of bacteriophage therapy using a standardized treatment pathway for patients with severe musculoskeletal infection. A multidisciplinary team approach in the form of an MPTF is paramount in this process.

Bacteriophages as Alternatives to Antibiotics in Clinical Care

Antimicrobial resistance is increasing despite new treatments being employed. With a decrease in the discovery rate of novel antibiotics, this threatens to take humankind back to a “pre-antibiotic era” of clinical care. Bacteriophages (phages) are one of the most promising alternatives to antibiotics for clinical use. Although more than a century of mostly ad-hoc phage therapy has involved substantial clinical experimentation, a lack of both regulatory guidance standards and effective execution of clinical trials has meant that therapy for infectious bacterial diseases has yet to be widely adopted. However, several recent case studies and clinical trials show promise in addressing these concerns. With the antibiotic resistance crisis and urgent search for alternative clinical treatments for bacterial infections, phage therapy may soon fulfill its long-held promise. This review reports on the applications of phage therapy for various infectious diseases, phage pharmacology, immunological responses to phages, legal concerns, and the potential benefits and disadvantages of this novel treatment.

Understanding Biofilms and Novel Approaches to the Diagnosis, Prevention, and Treatment of Medical Device-Associated Infections

Treatment of medical device-related infections is challenging and recurrence is common. The main reason for this is that microorganisms adhere to the surfaces of medical devices and enter into a biofilm state in which they display distinct growth rates, structural features, and protection from antimicrobial agents and host immune mechanisms compared with their planktonic counterparts. This article reviews how microorganisms form biofilms and the mechanisms of protection against antimicrobial agents and the host immune system provided by biofilms. Also discussed are innovative strategies for the diagnosis of biofilm-associated infection and novel approaches to treatment and prevention of medical device-associated infections.

New Innovations in the Treatment of PJI and Biofilms-Clinical and Preclinical Topics

PURPOSE OF REVIEW

Periprosthetic joint infection (PJI) is a devastating complication after total joint replacement. A main source for antibiotic tolerance and treatment failure is bacterial production of biofilm-a resilient barrier against antibiotics, immune system, and mechanical debridement. The purpose of this review is to explore some novel approaches to treat PJI and biofilm-related infections.

RECENT FINDINGS

Innovative treatment strategies of bacterial and biofilm infections revolve around (a) augmenting current therapies, such as improving the delivery and efficiency of conventional antibiotics and enhancing the efficacy of antiseptics and (b) administrating completely new therapeutic modalities, such as using immunotherapy, nanoparticles, lytic bacteriophages, photodynamic therapy, novel antibiotics, and antimicrobial peptides. Several promising treatment strategies for PJI are available to be tested further. The next requirement for most of the novel treatments is reproducing their effects in clinically representative animal models of PJI against clinical isolates of relevant bacteria.