In vitro activity of dalbavancin against biofilms of staphylococci isolated from prosthetic joint infections

Safety and Efficacy of Dalbavancin in Real Life: Retrospective Analysis of a Large Monocentric Case Series of Patients Treated for Skin/Soft Tissue and Other Difficult-to-Treat Infections

Background: Dalbavancin is a long-acting lipoglycopeptide, approved for treatment of skin and skin structure infections. Its PK/PD profile and safety allow for short hospital stays even in the case of difficult-to-treat infections requiring long courses of therapy, e.g., osteomyelitis, cardiovascular, and prosthetic infections. Objectives: We aimed to evaluate the safety and efficacy of dalbavancin in real life settings for both in-label and off-label indications. Methods: retrospective evaluation of all consecutive patients treated with dalbavancin at our site between May 2017 and September 2021. Results: A total of 100 patients treated with dalbavancin and followed up for 6 months after treatment (58% male; median age 63.5 years, median Charlson Comorbidity Index CCI = 2.7, 28% inpatients) were included with the following indications: acute bacterial skin and skin structure infections (22%), bone and prosthetic infections (57%), and cardiovascular infections (19%). Infections were caused by MSSA (30%), MRSA (5%), MR-CoNS (20%), and Streptococcus spp. (8%). In 32 cases, no isolate was obtained. The average number of infusions was 5 (s.d. = 3). Neither ensuing alteration of renal function nor neutropenia or thrombocytopenia were observed during treatment and follow-up. Two self-limiting skin rashes occurred. The overall clinical success rate was 84%-91% for registered and 82% for unregistered indications. The prescription of higher loading doses was the only predictor independently associated with better outcomes in multivariate models (OR: 5.2, 95%CI: 1.5-17.9, p < 0.01). Conclusions: Dalbavancin proved to be effective for skin and skin structure infections, as well as for difficult-to-treat infections in highly comorbid patients. Regarding tolerability, our results support the use of dalbavancin for long-lasting treatments of deep-seated infections.

Antibiofilm approaches as a new paradigm for treating infections

The lack of effective antibiotics for drug-resistant infections has led the World Health Organization to declare antibiotic resistance a global priority. Most bacterial infections are caused by microbes growing in structured communities called biofilms. Bacteria growing in biofilms are less susceptible to antibiotics than their planktonic counterparts. Despite their significant clinical implications, bacterial biofilms have not received the attention they warrant, with no approved antibiotics specifically designed for their eradication. In this paper, we aim to shed light on recent advancements in antibiofilm strategies that offer compelling alternatives to traditional antibiotics. Additionally, we will briefly explore the potential synergy between computational approaches, including the emerging field of artificial intelligence, and the accelerated design and discovery of novel antibiofilm molecules in the years ahead.

The MIC distribution of dalbavancin differs between different coagulase-negative staphylococci

Background

CoNS constitute a significant part of the human microbiota of skin and mucous membranes. They can cause nosocomial infections, and have shown decreased susceptibility to several antibiotics. The few remaining treatment options include (lipo)glycopeptides such as dalbavancin. However, there is a lack of knowledge concerning whether susceptibility to lipoglycopeptides varies between different species of CoNS.

Objectives

To determine the susceptibility to dalbavancin in different species of CoNS.

Methods

We investigated 480 bacterial isolates from 10 CoNS species: Staphylococcus epidermidis, Staphylococcus capitis, Staphylococcus caprae, Staphylococcus haemolyticus, Staphylococcus lugdunensis, Staphylococcus warneri, Staphylococcus pettenkoferi, Staphylococcus hominis, Staphylococcus sciuri and Staphylococcus simulans. The isolates were randomly selected from different sources of infection, including blood isolates, as well as deep and superficial infections. Antibiotic susceptibility was tested with the gradient test method.

Results

There was a statistically significant difference (ANOVA; P < 0.0001) in the MIC distribution for dalbavancin between different CoNS species. S. sciuri was the least susceptible species, with 90% of the isolates having an MIC value for dalbavancin above the EUCAST breakpoint of 0.125 mg/L. The lowest MIC90 values were seen for S. capitis, S. simulans and S. caprae (all 0.032 mg/L).

Conclusions

This study demonstrated a difference in dalbavancin susceptibility between different CoNS species, suggesting that species-specific breakpoints for CoNS should be further investigated.

Ototoxicity associated with extended dalbavancin treatment for a shoulder prosthetic joint infection

BACKGROUND

Dalbavancin is a lipoglycopeptide antibiotic approved for treatment of skin and soft tissue infections, administered as a single or two-dose treatment. The extended half-life, good penetration into bone and synovial fluid, and bactericidal activity against gram-positive bacteria, including those in biofilm, make dalbavancin an appealing choice for treatment of bone and joint infections in outpatient settings. However, we present a rare case of ototoxicity associated with off-label extended dalbavancin treatment of a prosthetic joint infection.

CASE PRESENTATION

A 55-year-old man with a prosthetic joint infection of the shoulder underwent off-label extended dalbavancin treatment, receiving a cumulative dose of 2500 mg. The patient experienced a gradual onset of hearing loss following the first dose, leading to a diagnosis of bilateral sensorineural hearing loss that persisted 1 year after dalbavancin was discontinued.

CONCLUSIONS

This case report highlights the importance of exercising caution when administering dalbavancin beyond approved dosing guidelines, and emphasizes the need for vigilance regarding the potential for ototoxicity.

Dalbavancin in Bone and Joint Infections: A Systematic Review

BACKGROUND

Approved for acute bacterial skin and skin structure infections, dalbavancin (DBV) has gradually acquired over the years a role as an off-label treatment for several infections caused by Gram-positive bacteria even in other anatomical sites. Osteoarticular (OA) infections are one of the most difficult-to-treat infections and, since the absence of recommendations, clinicians use different and heterogenic DBV dosing schedule regimens for the off-label treatment of osteomyelitis, spondylodiscitis, and septic arthritis. Our aim is to systematically review the current literature to describe DBV administration schedules and their outcome in OA infections.

METHODS

According to the 2020 updated PRISMA guidelines, all peer-reviewed articles regarding the use of DBV in OA infections were included. We conducted a literature search on PubMed and Cochrane Controlled Trials.

RESULTS

A total of 23 studies and 450 patients were included, prevalently male (144/195, 73.8%) and diabetic (53/163, 32.5%). Overall, 280 (280/388, 72.2%) osteomyelitis, 79 (79/388, 20.4%) spondylodiscitis, and 29 (29/388, 7.5%) septic arthritis were considered. Staphylococcus aureus (164/243, 67.5%) was the most common pathogen isolated. A previous treatment failure (45/96, 46.9%) was the main reason for a switch to a long-acting antibiotic. Most patients were successfully cured with DBV (318/401, 79.3%). A source control was performed in most patients with a favourable outcome (80.4%), while MRSA was prevalently isolated in people with an unfavourable outcome (57%). While a higher percentage of success was found in people who received three doses of DBV 1 week apart (92.3%), a higher rate of treatment failure was recorded in cases of when the DBV cycle was composed of less than two or more than four doses (27.8%).

CONCLUSIONS

DBV has shown to be effective as a treatment for OA infections. The most favourable outcome was found in patients receiving three doses of DBV and with an adequate surgical management prior to antibiotic treatment. Although a rigorous administration schedule does not exist, DBV is a viable treatment option in the management of OA infections.

Emerging resistance in Staphylococcus epidermidis during dalbavancin exposure: a case report and in vitro analysis of isolates from prosthetic joint infections

BACKGROUND

Dalbavancin, a semisynthetic lipoglycopeptide with exceptionally long half-life and Gram-positive spectrum, is an attractive option for infections requiring prolonged therapy, including prosthetic joint infections (PJIs).

OBJECTIVES

To investigate the prevalence of reduced susceptibility to dalbavancin in a strain collection of Staphylococcus epidermidis from PJIs, and to investigate genomic variation in isolates with reduced susceptibility selected during growth under dalbavancin exposure.

METHODS

MIC determination was performed on S. epidermidis isolates from a strain collection (n = 64) and from one patient with emerging resistance during treatment (n = 4). These isolates were subsequently cultured on dalbavancin-containing agar and evaluated at 48 h; MIC determination was repeated if phenotypical heterogeneity was detected during growth. Population analysis profile (PAP-AUC) was performed in isolates where a  ≥ 2-fold increase in MIC was detected, together with corresponding parental isolates (n = 21). Finally, WGS was performed.

RESULTS

All strains grew at 48 h on agar containing 0.125 mg/L dalbavancin. PAP-AUC demonstrated significant differences between parental and derived strains in four of the eight analysed groups. An amino acid change in the walK gene coinciding with emergence of phenotypic resistance was detected in the patient isolates, whereas no alterations were found in this region in the in vitro derived strains.

CONCLUSIONS

Exposure to dalbavancin may lead to reduced susceptibility to dalbavancin through either selection of pre-existing subpopulations, epigenetic changes or spontaneous mutations during antibiotic exposure. Source control combined with adequate antibiotic concentrations may be important to prevent emerging reduced susceptibility during dalbavancin treatment.

Off-Label Use of Dalbavancin for Sequential Treatment of Spondylodiscitis by Methicillin-Resistant Staphylococcus aureus: A Retrospective Single-Centre Experience

Background: Our aim was to describe the clinical outcome and safety of the sequential treatment with off-label dalbavancin in patients with spondylodiscitis that is caused by methicillin-resistant Staphylococcus aureus (MRSA). Methods: We retrospectively included all patients >18 years of age with spondylodiscitis that is caused by MRSA that was treated with dalbavancin from January 2018−January 2021, recording the instances of clinical cure/failure, adverse events, and the need to be re-hospitalized after the initiation of dalbavancin. In 2/15 patients, we performed therapeutic drug monitoring (TDM) for dalbavancin. Results: We included 15 patients, 53.3% of them were females, with a median age of 67.9 years (57.4−78.5); 100% patients reported back pain, while a fever was present only in 2/15 cases. The spondylodiscitis was localized in 86.6% cases at the lumbar level. A median of a 2-week in-hospital intravenous vancomycin was followed by dalbavancin with a median duration of 12 weeks (12−16). All patients reported a clinical cure, except for a woman who is still on a suppressive treatment. No patient needed to be re-hospitalized, access to emergency department, or experienced adverse events. The TDM for dalbavancin showed that more than 90% of the determinations were above the pharmacodynamic target against staphylococci. Conclusions: The results from our unique, even if it was small, cohort demonstrated that dalbavancin can be a safe/effective option as a sequential treatment in patients with serious infections requiring prolonged antibiotic therapy, such as spondylodiscitis.

A lipoglycopeptide antibiotic for Gram-positive biofilm-related infections

Drug-resistant Gram-positive bacterial infections are still a substantial burden on the public health system, with two bacteria ( Staphylococcus aureus and Streptococcus pneumoniae ) accounting for over 1.5 million drug-resistant infections in the United States alone in 2017. In 2019, 250,000 deaths were attributed to these pathogens globally. We have developed a preclinical glycopeptide antibiotic, MCC5145, that has excellent potency (MIC 90 ≤ 0.06 μg/ml) against hundreds of isolates of methicillin-resistant S. aureus (MRSA) and other Gram-positive bacteria, with a greater than 1000-fold margin over mammalian cell cytotoxicity values. The antibiotic has therapeutic in vivo efficacy when dosed subcutaneously in multiple murine models of established bacterial infections, including thigh infection with MRSA and blood septicemia with S. pneumoniae , as well as when dosed orally in an antibiotic-induced Clostridioides difficile infection model. MCC5145 exhibited reduced nephrotoxicity at microbiologically active doses in mice compared to vancomycin. MCC5145 also showed improved activity against biofilms compared to vancomycin, both in vitro and in vivo, and a low propensity to select for drug resistance. Characterization of drug action using a transposon library bioinformatic platform showed a mechanistic distinction from other glycopeptide antibiotics.

Comparative efficacy of dalbavancin alone and with rifampicin against in vitro biofilms in a pharmacodynamic model with methicillin-resistant Staphylococcus aureus

BACKGROUND

The anti-biofilm efficacy of dalbavancin has been evaluated in static models. Using an in vitro pharmacokinetic/pharmacodynamic model, we evaluated the comparative activity of dalbavancin alone and with rifampicin against biofilm-embedded methicillin-resistant S. aureus (MRSA).

METHODS

Two MRSA strains (HUB-4/HUB-5) were evaluated with the Calgary Device System and the dynamic CDC-Biofilm Reactor over 144 h. Dosage regimens simulated the human pharmacokinetics of dalbavancin (1500mg, single dose), vancomycin (1000mg/12 h) and linezolid (600mg/12 h), alone and with rifampicin (600mg/24 h). Efficacy was evaluated by assessing log10 CFU/mL changes (ΔlogCFU/mL) and we screened for resistance.

RESULTS

The minimal biofilm inhibitory/eradication concentrations of dalbavancin were 0.25/16 mg/L (HUB-4) and 0.25/8mg/L (HUB-5), respectively. In the pharmacokinetic/pharmacodynamic analysis, dalbavancin alone showed limited efficacy, but without resistance developing. Adding rifampicin improved the activities of dalbavancin, vancomycin, and linezolid, but rifampicin-resistant strains appeared over time in all cases. Dalbavancin-rifampicin was bactericidal against HUB-4 in the absence of resistance at 72 h and 144 h (ΔlogCFU/mL: -3.54±0.83, -4.32±0.12, respectively), an effect that was only achieved by linezolid-rifampicin at 144h (-3.33 ± 0.66). Against HUB-5, dalbavancin-rifampicin activity was impaired by rifampicin resistance to a greater extent than other combinations and had no bactericidal effect.

CONCLUSIONS

The anti-biofilm efficacy of dalbavancin was improved significantly by adding rifampicin. Although no dalbavancin resistance occurred, rifampicin resistance appeared in all combination therapies and decreased their efficacy over time. Dalbavancin-rifampicin in vitro treatment appears as promising anti-biofilm therapy, but further studies should evaluate the in vivo efficacy and the risk of resistance.

Role of Extracellular DNA in Dalbavancin Activity against Methicillin-Resistant Staphylococcus aureus (MRSA) Biofilms in Patients with Skin and Soft Tissue Infections

Methicillin-resistant Staphylococcus aureus (MRSA) has become the leading cause of skin and soft tissue infections (SSTIs). Biofilm production further complicates patient treatment, contributing to increased bacterial persistence and antibiotic tolerance. The study aimed to explore the efficacy of different antibiotics on biofilm-producing MRSA isolated from patients with SSTI. A total of 32 MRSA strains were collected from patients with SSTI. The MIC and minimal biofilm eradication concentration (MBEC) were measured in planktonic and biofilm growth. The study showed that dalbavancin, linezolid, and vancomycin all inhibited MRSA growth at their EUCAST susceptible breakpoint. Of the MRSA strains, 87.5% (n = 28) were strong biofilm producers (SBPs), while only 12.5% (n = 4) were weak biofilm producers (WBPs). The MBEC90 values for dalbavancin were significantly lower than those of linezolid and vancomycin in all tested strains. We also found that extracellular DNA (eDNA) contributes to the initial microbial attachment and biofilm formation. The amount of eDNA differed among MRSA strains and was significantly higher in those isolates with high dalbavancin and vancomycin tolerance. Exogenously added DNA increased the MBEC90 and protection of biofilm cells from dalbavancin activity. Of note, the relative abundance of eDNA was higher in MRSA biofilms exposed to MBEC90 dalbavancin than in untreated MRSA biofilms and those exposed to sub-MIC90. Overall, dalbavancin was the most active antibiotic against MRSA biofilms at concentrations achievable in the human serum. Moreover, the evidence of a drug-related increase of eDNA and its contribution to antimicrobial drug tolerance reveals novel potential targets for antibiofilm strategies against MRSA. IMPORTANCE Staphylococcus aureus is the most common cause of skin and soft tissue infections (SSTIs) worldwide. In addition, methicillin-resistant S. aureus (MRSA) is increasingly frequent in postoperative infections and responsible for a large number of hospital readmissions and deaths. Biofilm formation by S. aureus is a primary risk factor in SSTIs, due to a higher antibiotic tolerance. Our study showed that the biofilm-forming capacity varied among MRSA strains, although strong biofilm producers were significantly more abundant than weak biofilm producer strains. Notably, dalbavancin demonstrated a potent antibiofilm activity at concentrations achievable in human serum. Nevertheless, dalbavancin activity was affected by an increased concentration of extracellular DNA in the biofilm matrix. This study provides novel insight for designing more targeted therapeutic strategies against MRSA and to prevent or eradicate harmful biofilms.

Role of dalbavancin as combination therapy: evidences from the literature and clinical scenarios

INTRODUCTION

The off-label use of dalbavancin in patients with infections other than acute bacterial skin and skin structure infections (ABSSSI) represents an interesting therapeutic option. Its use as monotherapy or in combination with other antibiotics should be better defined.

AREAS COVERED

The aim of this review is to summarize evidence about the potential role of dalbavancin in combination with other antibiotics and describe clinical scenarios in which combination regimens including dalbavancin are useful. The studies were retrieved from PubMed using different combinations of keywords ("dalbavancin", "combination", "synergy").

EXPERT OPINION

Limited data about the use of dalbavancin in monotherapy or combined with other antibiotics are available. In vitro assays showed a synergistic effect of dalbavancin when combined with beta-lactam antibiotics. The use of dalbavancin as combination therapy in patients with ABSSSI did not demonstrate a superiority compared to monotherapy. Conversely, combination regimens including dalbavancin may be useful in specific infection types, such as bone and prosthetic joint infections or subacute/chronic intravascular infections with no possibility of device removal. Potential partner drugs might be rifampin, beta-lactams, fluoroquinolones, doxycycline and trimethoprim/sulfamethoxazole. The choice of the companion drug should be tailored on in vitro results of synergistic tests, patient's profile and type of infection.

Orthopaedic Implant-Associated Staphylococcal Infections: A Critical Reappraisal of Unmet Clinical Needs Associated with the Implementation of the Best Antibiotic Choice

Infections associated with orthopaedic implants represent a major health concern characterized by a remarkable incidence of morbidity and mortality. The wide variety of clinical scenarios encountered in the heterogeneous world of infections associated with orthopaedic implants makes the implementation of an optimal and standardized antimicrobial treatment challenging. Antibiotic bone penetration, anti-biofilm activity, long-term safety, and drug choice/dosage regimens favouring outpatient management (i.e., long-acting or oral agents) play a major role in regards to the chronic evolution of these infections. The aim of this multidisciplinary opinion article is to summarize evidence supporting the use of the different anti-staphylococcal agents in terms of microbiological and pharmacological optimization according to bone penetration, anti-biofilm activity, long-term safety, and feasibility for outpatient regimens, and to provide a useful guide for clinicians in the management of patients affected by staphylococcal infections associated with orthopaedic implants Novel long-acting lipoglycopeptides, and particularly dalbavancin, alone or in combination with rifampicin, could represent the best antibiotic choice according to real-world evidence and pharmacokinetic/pharmacodynamic properties. The implementation of a multidisciplinary taskforce and close cooperation between microbiologists and clinicians is crucial for providing the best care in this scenario.

A Dalbavancin Lock Solution Can Reduce Enterococcal Biofilms After Freezing

Introduction

We previously demonstrated the efficacy of a frozen dalbavancin–heparin (DH) lock solution against biofilms of staphylococci. However, as enterococci also commonly cause catheter-related bloodstream infections (C-RBSI), we assessed the bioactivity of frozen dalbavancin (D) and DH against enterococci.

Methods

Over 6 months, we compared the bioactivity of a solution of DH (1 mg/ml) with that of D in terms of cfu counts and metabolic activity against biofilms of Enterococcus faecalis and Enterococcus faecium (four strains each). For each solution, we individually compared results obtained at each time point (months 3 and 6) with baseline (month 0). We also compared the median DH value of each variable at baseline and at months 3 and 6 of freezing with the values obtained for D alone. We used both statistical and clinical criteria when results were within 25% of the reference value.

Results

At the end of the experiment (month 6), neither a statistically nor a clinically significant reduction in the bioactivity of D solution was observed in terms of cfu count and metabolic activity against enterococcal biofilms. Regarding the DH solution, we found both statistical and clinical significance in the median percentage reduction in metabolic activity between months 0 and 6 in E. faecalis strains (51.8% vs. 77.8%, P = 0.007). Moreover, after freezing, the DH solution lost significant bioactivity compared with the D solution, especially in E. faecalis.

Conclusion

A dalbavancin lock solution can be frozen for up to 6 months with no negative effect on its bioactivity against enterococcal biofilms. However, when combined with heparin, its efficacy was reduced. Therefore, we recommend that if lock therapy with frozen dalbavancin is used in the management of enterococcal C-RBSI, heparin should be added simultaneously at the time of catheter lock.

Rifabutin versus rifampicin bactericidal and antibiofilm activities against clinical strains of Staphylococcus spp. isolated from bone and joint infections

BACKGROUND

Staphylococci account for approximately 60% of periprosthetic joint infections (PJIs). Rifampicin (RMP) combination therapy is generally considered to be the treatment of choice for staphylococcal PJIs but carries an important risk of adverse events and drug-drug interactions. Rifabutin (RFB) shares many of the properties of rifampicin but causes fewer adverse events.

OBJECTIVES

To compare the minimal inhibitory concentration (MIC), the minimum bactericidal concentrations (MBC), and the minimum biofilm eradication concentrations (MBEC) of rifabutin and rifampicin for staphylococcal clinical strains isolated from PJIs.

METHODS

132 clinical strains of rifampicin-susceptible staphylococci [51 Staphylococcus aureus (SA), 48 Staphylococcus epidermidis (SE) and 33 other coagulase-negative staphylococci (CoNS)] were studied. The MBC and the MBEC were determined using the MBEC® Assay for rifabutin and rifampicin and were compared.

RESULTS

When compared with the rifampicin MIC median value, the rifabutin MIC median value was significantly higher for SA (P < 0.05), but there was no statistically significant difference for SE (P = 0.25) and CoNS (P = 0.29). The rifabutin MBC median value was significantly higher than that of rifampicin for SA (P = 0.003) and was lower for SE (P = 0.003) and CoNS (P = 0.03). Rifabutin MBEC median value was statistically lower than that of rifampicin for all strains tested.

CONCLUSIONS

Using the determination of MBEC values, our study suggests that rifabutin is more effective than rifampicin against clinical strains of Staphylococcus spp. obtained from PJIs. Using MBECs instead of MICs seems to be of interest when considering biofilms. In vivo higher efficacy of rifabutin when compared with rifampicin needs to be confirmed.

Biofilm-Related Infections in Gram-Positive Bacteria and the Potential Role of the Long-Acting Agent Dalbavancin

Infections caused by Gram-positive bacteria are a major public health problem due to their increasing resistance to antibiotics. Staphylococcus and Enterococcus species' resistance and pathogenicity are enhanced by their ability to form biofilm. The biofilm lifestyle represents a significant obstacle to treatment because bacterial cells become highly tolerant to a wide range of antimicrobial compounds normally effective against their planktonic forms. Thus, novel therapeutic strategies targeting biofilms are urgently needed. The lipoglycopeptide dalbavancin is a long-acting agent for treating acute bacterial skin and skin structure infections caused by a broad range of Gram-positive pathogens. Recent studies have shown promising activity of dalbavancin against Gram-positive biofilms, including methicillin-resistant S. aureus (MRSA), methicillin-resistant S. epidermidis (MRSE), and vancomycin-susceptible enterococci. This review outlines the mechanisms regulating biofilm development in Staphylococcus and Enterococcus species and the clinical impact of biofilm-related infections. In addition, it discusses the clinical implications and potential therapeutic perspectives of the long-acting drug dalbavancin against biofilm-forming Gram-positive pathogens.

Evaluation of intraosteoblastic activity of dalbavancin against Staphylococcus aureus in an ex vivo model of bone cell infection

OBJECTIVES

Long-acting lipoglycopeptides are promising therapeutic options in Staphylococcus aureus bone and joint infections (BJIs). This study evaluated the ability of dalbavancin to eradicate the intraosteoblastic reservoir of S. aureus, associated with BJI chronicity.

METHODS

Osteoblastic cells were infected with a standardized inoculum of the S. aureus reference strain HG001 and incubated for 24 h with dalbavancin, vancomycin or rifampicin using the MIC, 10×MIC, 100×MIC and/or the intraosseous concentrations reached using standard therapeutic doses (i.e. vancomycin, 10 mg/L; rifampicin, 2 mg/L; and dalbavancin, 6 mg/L). The remaining intracellular bacteria were quantified by plating cell lysates.

RESULTS

MICs of dalbavancin, vancomycin and rifampicin were 0.125, 1 and 0.004 mg/L, respectively. Dalbavancin significantly reduced the intracellular inoculum of S. aureus starting at a concentration equal to the MIC, with a significant dose effect, ranging from a reduction of 31.4% (95% CI = 17.6%-45.2%) at MIC to 51.6% (95% CI = 39.8%-63.4%) at 100×MIC compared with untreated cells. Of note, dalbavancin was the only molecule to significantly reduce the intraosteoblastic inoculum at low concentration (MIC). At intraosseous concentrations, dalbavancin reduced the intracellular inoculum by 49.6% (95% CI = 45.1%-54.1%) compared with untreated cells (P < 0.001), with no significant difference compared with vancomycin (38.1%; 95% CI = 19.2%-57.0%; P = 0.646), and was less efficient than rifampicin (69.0%; 95% CI = 63.2-74.8; P < 0.001).

CONCLUSIONS

Dalbavancin was able to decrease the intraosteoblastic S. aureus inoculum by 50% at intraosseous concentrations reached during standard human therapeutic dosing, with no difference compared with vancomycin, and remained less efficient than rifampicin. However, it was the only molecule significantly active at low concentration.

In vitro activity of dalbavancin and other anti-staphylococcal agents against infecting isolates of methicillin-resistant coagulase-negative staphylococci

Introduction. Dalbavancin was approved in Europe in 2015 for skin and soft tissue infections.Hypothesis/Gap Statement. Data on methicillin-resistant coagulase-negative staphylococci (MR-CNS) dalbavancin susceptibility are scarce.Aim. To assess the susceptibility of MR-CNS to dalbavancin and other anti-staphylococcal agents.Methodology. A total of 443 MR-CNS clinical isolates from patients hospitalized in a Greek university hospital during a 2.5-year period (January 2018 to June 2020) were included. The MICs for vancomycin, teicoplanin, linezolid and daptomycin were investigated by Etest and the MIC for dalbavancin was determined according to European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines in 196 isolates. The consumption of the aforementioned antimicrobials was calculated.Results. In total, 51 isolates were resistant to teicoplanin (11.5 %) and 211 (47.6 %) to linezolid; all were susceptible to vancomycin and daptomycin. Among 196 isolates tested, 32 (16.3 %) were resistant to dalbavancin. A significant increase of MIC during the study period was found for vancomycin, teicoplanin and daptomycin, while a decrease in linezolid's MIC was observed. Dalbavancin's MIC remained stable. No difference in consumption was observed among the studied anti-staphylococcal agents.Conclusion. An increase of vancomycin, teicoplanin and daptomycin MICs among MR-CNS was observed, whereas 47.6 % of isolates were non-susceptible to linezolid. Dalbavancin retains excellent potency against MR-CNS, even in the presence of non-susceptibility to other anti-staphylococcal antibiotics.

Role or oritavancin and dalbavancin in acute bacterial skin and skin structure infections and other potential indications

PURPOSE OF REVIEW

To discuss the currently available evidence about the use oritavancin and dalbavancin for the treatment of acute bacterial skin and skin structure infections (ABSSSI) and for other potential indications.

RECENT FINDINGS

In this review, we briefly summarize the available data on efficacy (from randomized controlled trials) and on effectiveness and cure rates (from observational studies) pertaining to the use of oritavancin and dalbavancin either for ABSSSI or for other indications.

SUMMARY

Oritavancin and dalbavancin are valid options for outpatient therapy and early discharge in patients with ABSSSI, especially when adherence to oral therapy cannot be guaranteed or no oral choices are available. Furthermore, it is worth noting that a non-negligible portion (sometimes the majority) of oritavancin and dalbavancin use in available real-life experiences is for indications other than ABSSSI, especially for Gram-positive osteomyelitis and endocarditis. The number of studies on the use of long-acting lipoglycopeptides for these currently off-label indications is rapidly increasing and will help to further optimize the use of these peculiar antibiotics in the forthcoming future.

Real-World Use of Dalbavancin in the Era of Empowerment of Outpatient Antimicrobial Treatment: A Careful Appraisal Beyond Approved Indications Focusing on Unmet Clinical Needs

Dalbavancin is a novel, long-acting lipoglycopeptide characterized by a long elimination half-life coupled with excellent in vitro activity against multidrug-resistant Gram-positives. Although it is currently approved only for the treatment of acute bacterial skin and skin structure infections, an ever-growing amount of evidence supports the efficacy of dalbavancin as a long-term therapy in osteomyelitis, prosthetic joint infections, endocarditis, and bloodstream infections. This article provides a critical reappraisal of real-world use of dalbavancin for off-label indications. A search strategy using specific keywords (dalbavancin, osteomyelitis, endocarditis, long-term suppressive therapy, bloodstream infection, pharmacokinetic/pharmacodynamic profile) until April 2021 was performed on the PubMed-MEDLINE database. As for other novel antibiotics, a conundrum between approved indications and potential innovative therapeutic uses has emerged for dalbavancin as well. The promising efficacy in challenging scenarios (i.e., osteomyelitis, endocarditis, prosthetic joint infections), coupled with the unique pharmacokinetic/pharmacodynamic properties, makes dalbavancin a valuable alternative to daily in-hospital intravenous or outpatient antimicrobial regimens in the treatment of long-term Gram-positive infections. This makes dalbavancin valuable in the current COVID-19 scenario, in which hospitalization and territorial medicine empowerment are unavoidable.

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.

Efficacy of dalbavancin against MRSA biofilms in a rat model of orthopaedic implant-associated infection

OBJECTIVES

The aim of this study was to evaluate the efficacy of dalbavancin against MRSA biofilm-related infection in orthopaedic implants in vivo.

METHODS

One MRSA strain isolated from human osteomyelitis was used to promote biofilm formation on the surface of screws. The implants were inserted in the proximal tibia under general anaesthesia. Thirty-nine Wistar rats were divided into three groups [control group (no treatment), Group 1 (7 days of treatment) and Group 2 (14 days of treatment)]; both treatment groups were administered dalbavancin intraperitoneally and euthanized after treatment. cfu of bacteria present in both the tibia and the implant were quantified. The infection severity was assessed by histopathology and scored from 0 (no infection) to 4 (severe infection).

RESULTS

The high number of cfu/g and cfu/mL present in the control group indicated a well-established infection. There was a significant reduction in cfu in rats treated with dalbavancin both in the tibia (2.8 × 105 cfu/g) and the implant (1.1 × 106 cfu/mL) in Group 1 (1.8 × 103 cfu/g and 2.4 × 105 cfu/mL, respectively) and in Group 2 (8.2 cfu/g and 8.2 × 103 cfu/mL, respectively). Most animals from the control group presented an infection scored as 3 (severe). At the end of the experiment, most rats from Groups 1 and 2 presented an infection scored as 2 (moderate) and 0 (no infection), respectively.

CONCLUSIONS

Although there was a marked decrease in cfu number, signs of biofilm-induced infection prevailed after 14 days of treatment. Further studies should be carried out to evaluate the potential of dalbavancin in the treatment of bone and orthopaedic implant-associated MRSA infections.

Dalbavancin for the Treatment of Prosthetic Joint Infections: A Narrative Review

Dalbavancin (DAL) is a lipoglycopeptide with bactericidal activity against a very wide range of Gram-positive microorganisms. It also has unique pharmacokinetic properties, namely a prolonged half-life (around 181 h), which allows a convenient weekly dosing regimen, and good diffusion in bone tissue. These features have led to off-label use of dalbavancin in the setting of bone and joint infection, including prosthetic joint infections (PJI). In this narrative review, we go over the pharmacokinetic and pharmacodynamic characteristics of DAL, along with published in vitro and in vivo experimental models evaluating its activity against biofilm-embedded bacteria. We also examine published experience of osteoarticular infection with special attention to DAL and PJI.

Dalbavancin Efficacy and Impact on Hospital Length-of-Stay and Treatment Costs in Different Gram-Positive Bacterial Infections

Background and Objectives

The study aimed to evaluate the impact of dalbavancin therapy on both hospital length-of-stay (LOS) and treatment-related costs, as well as to describe the clinical outcome, in a retrospective cohort of patients with diverse Gram-positive bacterial infections, hospitalized in different specialty Units.

Methods

From July 2017 to July 2019, clinical and sociodemographic data were collected for all hospitalized patients switched to dalbavancin for the treatment of Gram-positive infections. LOS and treatment-related costs were assessed and compared to a hypothetical scenario where the initial standard antimicrobial therapy would have been administered in hospital for the same duration as dalbavancin.

Results

A total of 50 patients were enrolled. The observed infections were: acute bacterial skin and skin structure infections (ABSSSIs, 12 patients), complicated ABSSSIs (eight patients), osteoarticular infections (18 patients), vascular graft or cardiovascular implantable electronic devices (CIED) infections (12 patients). After a median of 14 [interquartile range (IQR) 7–28] days, the in-hospital antimicrobial therapy was switched to dalbavancin 1500 mg. When appropriate, considering the site and the clinical course of the infection, 1500 mg doses were repeated every 14 days until recovery. Overall, 49/50 (98%) patients reported clinical success at the end of therapy. No relapses were observed in 37 patients for whom a median follow-up of 150 (IQR 30–180) days was available. By switching to dalbavancin, a median of €8,259 (IQR 5644–17,270) and 14 hospital days (IQR 22–47) per patient were saved.

Conclusions

In this experience, the use of dalbavancin contributed to shorten LOS and treatment-related costs, especially in difficult Gram-positive infections requiring prolonged therapy.

In Vitro Activity of Vancapticin MCC5145 against Methicillin-Resistant Staphylococcus aureus from Periprosthetic Joint Infection

MRSA periprosthetic 1 joint infection (PJI) can be challenging to treat due to biofilm formation, alongside sometimes limited vancomycin activity (1-3).….

Population pharmacokinetics of dalbavancin and dosing consideration for optimal treatment of adult patients with staphylococcal osteoarticular infections

Background: Dalbavancin is gaining interest in the treatment of complex osteoarticular (OA) infections.Objective: To conduct a population pharmacokinetic analysis of dalbavancin in a prospective cohort of adult patients with Gram-positive OA infections and to identify optimal dosing regimens for long term-treatment.Methods: Non-linear mixed-effects modelling was performed with Monolix. Monte Carlo simulations were performed with six dalbavancin regimens (1500mg at day 1; 1000mg at day 1 plus 500mg at day 8; 1500mg at day1 and 8; 1500mg at day1 and 8 plus 500, 1000 or 1500mg at day 36) to assess the PTA of three pharmacodynamic target of fAUC_24h/MIC against S. aureus (>27.1, 53.3 and 111.1). Cumulative fraction of response (CFR) was calculated against MIC distribution of both MRSA and MSSA as well. Desirable PTAs and CFRs were ≥90%.Results: Fifteen patients provided 120 plasma concentrations. Most (73.3%) had prosthetic joint infections. Clinical cure rate was 87%. A two-compartment model with linear elimination well described the data. No covariate was retained in the final model. Pharmacokinetic dalbavancin estimates were 0.106L/h for CL and 36.4L for V_ss The tested dosing regimens granted desirable CFRs against S. aureus at the most effective PK/PD target for a period ranging 3-to-9 weeks. Conclusion: Giving a two 1500mg dosing regimen of dalbavancin one week apart may ensure efficacy against both MSSA and MRSA up to 5 weeks in patients with OA infections. Clinical assessment at that time may allow for considering whether or not an additional dose should be administered for prolonging effective treatment.

Challenges of antibiotic resistance biofilms and potential combating strategies: a review

In this modern era, medicine is facing many alarming challenges. Among different challenges, antibiotics are gaining importance. Recent years have seen unprecedented increase in knowledge and understanding of various factors that are root cause of the spread and development of resistance in microbes against antibiotics. The infection results in the formation of microbial colonies which are termed as biofilms. However, it has been found that a multiple factors contribute in the formation of antimicrobial resistance. Due to higher dose of Minimum Bactericidal Concentration (MBC) as well as of Minimum Inhibitory Concentration (MIC), a large batch of antibiotics available today are of no use as they are ineffective against infections. Therefore, to control infections, there is dire need to adopt alternative treatment for biofilm infection other than antibiotics. This review highlights the latest techniques that are being used to cure the menace of biofilm infections. A wide range of mechanisms has been examined with particular attention towards avenues which can be proved fruitful in the treatment of biofilms. Besides, newer strategies, i.e., matrix centered are also discussed as alternative therapeutic techniques including modulating microbial metabolism, matrix degrading enzyme, photodynamic therapy, natural compounds quorum sensing and nanotechnology which are being used to disrupt extra polymeric substances (EPS) matrix of desired bacterial biofilms.

The role of dalbavancin for Gram positive infections in the COVID-19 era: state of the art and future perspectives

INTRODUCTION

The COVID-19 pandemic has dramatically challenged the national health systems worldwide in the last months. Dalbavancin is a novel antibiotic with a long plasmatic half-life and simplified weekly administration regimens, thus representing a promising option for the outpatient treatment of Gram-positive infections and the early discharge of hospitalized patients. Dalbavancin is approved for the treatment of acute bacterial skin and skin structure infections (ABSSSIs). Many preliminary data seem to support its use in other indications, such as osteomyelitis, prosthetic joint infections, and infective endocarditis.

AREAS COVERED

A search in the literature using validated keywords (dalbavancin, Gram-positive infections, Gram-positive cocci, ABSSSI, intravenous treatment, and long-acting antibiotics) was conducted on biomedical bibliographic databases (PubMed and Embase) from 2004 to 30 September 2020. Results were analyzed during two consensus conferences with the aim to review the current evidence on dalbavancin in Gram-positive infections, mainly ABSSSI, osteomyelitis, and infective endocarditis, highlight the main limitations of available studies and suggest possible advantages of the molecule.

EXPERT OPINION

The board identifies some specific subgroups of patients with ABSSSIs who could mostly benefit from a treatment with dalbavancin and agrees that the design of homogenous and robust studies would allow a broader use of dalbavancin even in other clinical settings.

In Vitro Study To Evaluate the Bioactivity of Freezing a Heparin-Based Dalbavancin Lock Solution

The use of dalbavancin as a catheter lock solution must be addressed in depth before implementation in clinical practice. We assessed whether a heparin-based dalbavancin lock solution could be frozen in single-dose vials for 6 months without affecting its bioactivity against biofilms of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus epidermidis (MRSE). Over 6 months, we tested the bioactivity of a frozen solution of dalbavancin (≈1 mg/ml) plus heparin (60 IU) in terms of CFU counts and metabolic activity against biofilms of Staphylococcus aureus ATCC 43300 (MRSA) and Staphylococcus epidermidis ATCC 35984 (MRSE). The Anti-Xa assay was also performed to assess whether the anticoagulant activity of heparin was reduced under freezing. Every month, we compared the mean value of each variable with that obtained at baseline (before freezing, month 0) using both clinical criteria (values were within 25% of the baseline value) and statistical criteria (linear mixed models). At the end of the experiment (month 6), neither a clinically nor a statistically significant reduction in the bioactivity of dalbavancin-heparin solution was observed in terms of CFU counts and metabolic activity against biofilm of MRSA. Regarding MRSE, considering the clinical criteria, neither CFU counts nor metabolic activity decreased significantly. However, the reduction was statistically significant for all variables. Anti-Xa values (mean [standard deviation] international units per milliliter) for heparin in combination with dalbavancin were within 25% of the heparin-water value. A heparin-based dalbavancin lock solution can be frozen for up to 6 months with no effect on its bioactivity against MRSA and MRSE biofilms.

Prosthetic joint infections: clinical management, diagnosis, and treatment

PURPOSE OF REVIEW

Prosthetic joint infections (PJIs) represent one of the most disastrous complications in prosthetic surgery, requiring long hospitalization, prolonged antimicrobial treatment and repeated surgical interventions. No gold standard test to formulate diagnosis exist. A combination of high index of suspicion, physical examination, microbiological and biohumoral investigations is required. Therapeutical approach should be based on a multidisciplinary team. In our center, a two-stage approach is preferred. As regards the choice of the empirical antibiotic backbone, individual risk factors for multiple-drug resistant (MDR) pathogens should be considered. Several studies enhance the possibility to shorten the length of antibiotic couses.

RECENT FINDINGS

Some interesting improvements have been made in the setting of PJIs management. As regards diagnosis, novel biomarkers and nuclear imaging are acquiring more importance. Molecular biology techniques also offer the possibility to formulate rapid microbiological identification. The pattern of PJIs is evolving towards higher rates of MDR causes. During the last decade, a number of new antibiotic molecules with activity against MDRs have been approved. Some of them are also available either in oral formulation or as long-acting compounds, offering the opportunity for early patient's discharge, with expected healthcare costs saving.

SUMMARY

Management of PJIs still represents a major threat for clinicians. Improvements in surgical techniques and antibiotic pipeline promise to revolutionize the approach in next years. Despite data from our experience confirm the efficacy of shorter antibiotic courses and the value of new molecules, randomized clinical trials are lacking. More data are needed in order to modify the routine clinical practice.

Effect of Dalbavancin on Staphylococcal Biofilms When Administered Alone or in Combination With Biofilm-Detaching Compounds

Microorganisms grown in biofilms are more resistant to antimicrobial treatment and immune system attacks compared to their planktonic forms. In fact, infections caused by biofilm-forming Staphylococcus aureus and Staphylococcus epidermidis are a large threat for public health, including patients with medical devices. The aim of the current manuscript was to test the effect of dalbavancin, a recently developed lipoglycopeptide antibiotic, alone or in combination with compounds contributing to bacterial cell disaggregation, on staphylococcal biofilm formation and elimination. We used real-time impedance measurements in microtiter plates to study biofilm growth dynamics of S. aureus and S. epidermidis strains, in the absence or presence of dalbavancin, linezolid, vancomycin, cloxacillin, and rifampicin. Further experiments were undertaken to check whether biofilm-detaching compounds such as N-acetylcysteine (NAC) and ficin could enhance dalbavancin efficiency. Real-time dose–response experiments showed that dalbavancin is a highly effective antimicrobial, preventing staphylococcal biofilm formation at low concentrations. Minimum biofilm inhibitory concentrations were up to 22 higher compared to standard E-test values. Dalbavancin was the only antimicrobial that could halt new biofilm formation on established biofilms compared to the other four antibiotics. The addition of NAC decreased dalbavancin efficacy while the combination of dalbavancin with ficin was more efficient than antibiotic alone in preventing growth once the biofilm was established. Results were confirmed by classical biofilm quantification methods such as crystal violet (CV) staining and viable colony counting. Thus, our data support the use of dalbavancin as a promising antimicrobial to treat biofilm-related infections. Our data also highlight that synergistic and antagonistic effects between antibiotics and biofilm-detaching compounds should be carefully tested in order to achieve an efficient treatment that could prevent both biofilm formation and disruption.

The role of dalbavancin in the treatment of acute bacterial skin and skin structure infections (ABSSSIs)

Introduction: Acute bacterial skin and skin-structure infections (ABSSSI) are a subgroup of skin and soft tissue infections and are a common source of morbidity in both the community and the hospital setting. The most common cause of ABSSSI is Staphylococcus aureus, which also includes methicillin-resistant S. aureus (MRSA), together with beta-hemolytic streptococci, enterococci, and Gram-negative bacteria. Since the emergence of MRSA, the management of ABSSSI has become more challenging. Novel therapies alternative to teicoplanin and vancomycin, intravenous agents commonly used against MRSA and employed in hospitalized patients, and to other antibiotics which are used as standard of care for MRSA infection, with a higher efficacy and safer profile are worth evaluating.Areas covered: This review presents and discusses current evidence on the use of dalbavancin in the treatment of ABSSSI.Expert opinion: Dalbavancin represents a promising therapeutic choice in patients with ABSSSI, thanks to its favorable pharmacokinetic profile, valuable antimicrobial spectrum, and good safety profile.

Can dalbavancin be used as a catheter lock solution?

Purpose. The new lipoglycopeptide dalbavancin has only been approved for acute bacterial skin and skin structure infections. However, its alternative use as a catheter lock solution could facilitate the conservative management of catheter-related bloodstream infection. Our objective was to assess the stability and activity of dalbavancin alone and in combination with heparin against methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus epidermidis (MRSE) biofilms. We also compared the results with those obtained with vancomycin alone and in combination with heparin.Methodology. We used a 96-well plate in vitro model based on 24 h biofilms of MRSA and MRSE (ATCC 43300, ATCC 35984 and one clinical strain of each). The biofilms were exposed to dalbavancin (0.128 mg ml^-1) and vancomycin (5 mg ml^-1) alone and in combination with heparin (60 IU). The median percentage reductions in metabolic activity, biomass, bacterial load, and cell viability for each solution were compared.Results. Dalbavancin combined with heparin significantly reduced the median [interquartile range (IQR)] percentage of metabolic activity in MRSA biofilms compared with vancomycin [90.0 % (70.4-92.9 %) versus 35.0 % (14.8-59.6 %), P=0.006]. For the remaining variables studied, the combination was not inferior to vancomycin for MRSA and MRSE.Conclusions. Dalbavancin proved to be active against MRSA and MRSE biofilms. The combination of dalbavancin with heparin is a promising catheter lock solution that has the advantage of locking the catheter at home for 7 days.

Successful treatment of methicillin-sensitive Staphylococcus aureus tricuspid-valve endocarditis with dalbavancin as an outpatient in a person who injects drugs: A case report

There is a paucity of literature on the use of dalbavancin, a long-acting lipoglycopeptide, in infective endocarditis. Existing case reports have investigated dalbavancin in endocarditis as a sequential treatment after clearance of bacteria from the bloodstream with conventional therapy. A 27-year-old female who injects drugs presented with fever and pleuritic chest pain and was found to have methicillin-sensitive Staphylococcus aureus tricuspid-valve endocarditis with septic pulmonary emboli. Given non-adherence with conventional therapy, she was successfully treated off-label with once-weekly dalbavancin infusions in an outpatient setting. We summarize the patient's clinical course and review published reports of endocarditis treated with dalbavancin in the peer-reviewed literature. Our case supports further investigation of outpatient dalbavancin infusions as a reasonable therapeutic alternative to standard treatment with daily intravenous therapy for serious staphylococcal infections among patients who have difficulty engaging with conventional therapy.

Phenazine Antibiotic-Inspired Discovery of Bacterial Biofilm-Eradicating Agents

Bacterial biofilms are surface-attached communities of slow-growing and non-replicating persister cells that demonstrate high levels of antibiotic tolerance. Biofilms occur in nearly 80 % of infections and present unique challenges to our current arsenal of antibiotic therapies, all of which were initially discovered for their abilities to target rapidly dividing, free-floating planktonic bacteria. Bacterial biofilms are credited as the underlying cause of chronic and recurring bacterial infections. Innovative approaches are required to identify new small molecules that operate through bacterial growth-independent mechanisms to effectively eradicate biofilms. One source of inspiration comes from within the lungs of young cystic fibrosis (CF) patients, who often endure persistent Staphylococcus aureus infections. As these CF patients age, Pseudomonas aeruginosa co-infects the lungs and utilizes phenazine antibiotics to eradicate the established S. aureus infection. Our group has taken a special interest in this microbial competition strategy and we are investigating the potential of phenazine antibiotic-inspired compounds and synthetic analogues thereof to eradicate persistent bacterial biofilms. To discover new biofilm-eradicating agents, we have established an interdisciplinary research program involving synthetic medicinal chemistry, microbiology and molecular biology. From these efforts, we have identified a series of halogenated phenazines (HPs) that potently eradicate bacterial biofilms, and future work aims to translate these preliminary findings into ground-breaking clinical advances for the treatment of persistent biofilm infections.

DALBACEN cohort: dalbavancin as consolidation therapy in patients with endocarditis and/or bloodstream infection produced by gram-positive cocci

OBJECTIVES

To analyse the effectiveness of dalbavancin (DBV) in clinical practice as consolidation therapy in patients with bloodstream infection (BSI) and/or infective endocarditis (IE) produced by gram-positive cocci (GPC), as well as its safety and pharmacoeconomic impact.

METHODS

A multicentre, observational and retrospective study was conducted of hospitalised patients with IE and/or BSI produced by GPC who received at least one dose of DBV. Clinical response was assessed during hospitalization, at 3 months and at 1 year.

RESULTS

Eighty-three patients with median age of 73 years were enrolled; 73.5% were male; 59.04% had BSI and 49.04% IE (44.04% prosthetic valve IE, 32.4% native IE, 23.5% pacemaker lead). The most frequently isolated microorganism was Staphylococcus aureus in BSI (49%) and coagulase-negative staphylococci in IE (44.1%). All patients with IE were clinically cured in hospital; at 12 months, there was 2.9% loss to follow-up, 8.8% mortality unrelated to IE, and 2.9% therapeutic failure rate. The percentage effectiveness of DBV to treat IE was 96.7%. The clinical cure rate for BSI was 100% during hospital stay and at 3 months; there were no recurrences or deaths during the follow-up. No patient discontinued treatment for adverse events. The saving in hospital stay was 636 days for BSI (315,424.20€) and 557 days for IE (283,187.45€).

CONCLUSIONS

DBV is an effective consolidation antibiotic therapy in clinically stabilized patients with IE and/or BSI. It proved to be a cost-effective treatment, reducing the hospital stay, thanks to the pharmacokinetic/pharmacodynamic profile of this drug.

Dalbavancin Use in Vulnerable Patients Receiving Outpatient Parenteral Antibiotic Therapy for Invasive Gram-Positive Infections

Introduction

Dalbavancin is approved for acute bacterial skin and skin structure infections (ABSSSIs) but offers a potential treatment option for complicated invasive gram-positive infections. Importantly, dalbavancin’s real benefits may be in treating complicated infections in vulnerable patient populations, such as persons who inject drugs (PWID).

Methods

A multicenter retrospective analysis was performed from March 2014 to April 2017 to assess 30- and 90-day clinical cure and adverse drug events (ADEs) in adult patients who received ≥ 1 dose of dalbavancin for a non-ABSSSI indication.

Results

During the study period, 45 patients received dalbavancin, 28 for a non-ABSSSI indication. The predominant infections treated included osteomyelitis (46%), endovascular infection (25%) and uncomplicated bacteremia (14%). Half of the patients had positive Staphylococcus aureus in cultures, 29% methicillin resistant and 21% methicillin susceptible. Most patients were prescribed dalbavancin as sequential treatment with a median of 13.5 days of prior antibiotic therapy. The most common reason for choosing dalbavancin over standard therapy use was PWID (54%). Seven patients were lost to follow-up at day 30. Of the remaining evaluable patients, 30-day clinical cure was achieved in 15/21 (71%) patients. The most common reason for failure was lack of source control (4/6, 67%). At day 90, relapse occurred in two patients. Three patients had a potential dalbavancin-associated ADE: two patients with renal dysfunction and one patient with pruritus.

Conclusions

This study demonstrates a possible role for dalbavancin in the treatment of non-ABSSSI invasive gram-positive infections in select vulnerable OPAT patients.

Safety and Efficacy of Prolonged Use of Dalbavancin in Bone and Joint Infections

Dalbavancin is a lipoglycopeptide with potent activity against Gram-positive microorganisms, a long half-life, a favorable safety profile, and a high concentration in bone, which makes it an interesting alternative for treatment of osteoarticular infections. We performed a multicentric retrospective study of all patients with an osteoarticular infection (septic arthritis, spondylodiscitis, osteomyelitis, or orthopedic implant-related infection) treated with at least one dose of dalbavancin between 2016 and 2017 in 30 institutions in Spain. In order to evaluate the response, patients with or without an orthopedic implant were separated. A total of 64 patients were included. Staphylococcus epidermidis and Staphylococcus aureus were the most frequent microorganisms. The reasons for switching to dalbavancin were simplification (53.1%), adverse events (25%), or failure (21.9%). There were 7 adverse events, and no patient had to discontinue dalbavancin. In 45 cases, infection was related to an orthopedic implant. The implant material was retained in 23 cases, including that in 15 (65.2%) patients that were classified as cured and 8 (34.8%) that presented improvement. In 21 cases, the implants were removed, including those in 16 (76.2%) cases that were considered successes, 4 (19%) cases were considered improved, and 1 (4.8%) case that was considered a failure. Among the 19 cases without implants, 14 (73.7%) were considered cured, 3 (15.8%) were considered improved, and 2 (10.5%) were considered failures. The results show that dalbavancin is a well-tolerated antibiotic, even when >2 doses are administered, and is associated with a high cure rate. These are preliminary data with a short follow-up; therefore, it is necessary to gain more experience and, in the future, to establish the most appropriate dose and frequency.

Emergence of a dalbavancin induced glycopeptide/lipoglycopeptide non-susceptible Staphylococcus aureus during treatment of a cardiac device-related endocarditis

In the present study, we demonstrated the emergence of dalbavancin non-susceptible and teicoplanin-resistant Staphylococcus aureus small colony variants which were selected in vivo through long-term treatment with dalbavancin. A 36-year-old man presented with a cardiac device-related S. aureus endocarditis and received long-term therapy with dalbavancin. Consecutively, two glycopeptide/lipoglycopeptide susceptible and two non-susceptible S. aureus isolates were obtained from blood cultures and the explanted pacemaker wire. The isolates were characterized by: standard typing methods, antimicrobial susceptibility testing, auxotrophic profiling, proliferation assays, scanning and transmission electron microscopy, as well as whole genome sequencing. The isolated SCVs demonstrated a vancomycin-susceptible but dalbavancin non-susceptible and teicoplanin-resistant phenotype whereof the respective MICs of the last isolate were 16- and 84-fold higher than the susceptible strains. All four strains were indistinguishable or at least closely related by standard typing methods (spa, MLST, and PFGE), and whole genome sequencing revealed only eight sequence variants. A consecutive increase in cell wall thickness (up to 2.1-fold), an impaired cell separation with incomplete or multiple cross walls and significantly reduced growth rates were observed in the present study. Therefore, the mutations in pbp2 and the DHH domain of GdpP were identified as the most probable candidates due to their implication in the biosynthesis and metabolism of the staphylococcal cell wall. For the first time, we demonstrated in vivo induced dalbavancin non-susceptible/teicoplanin resistant, but vancomycin and daptomycin susceptible S. aureus SCVs without lipopeptide or glycopeptide pretreatment, thus, indicating the emergence of a novel lipoglycopeptide resistance mechanism.

A Review of Novel Antibiotic Regimens for the Treatment of Orthopedic Infections

As a result of the increasing numbers of joint replacement surgeries and other implant-associated procedures performed, the incidences of periprosthetic joint infections and osteomyelitis are on the rise. Antibiotic resistance to gram-positive species, which are mostly isolated from such infections, is a significant obstacle in clinical practice. Promising clinical outcomes have been reported with the use of novel antibiotics for patients with periprosthetic joint infections and osteomyelitis. Further research is necessary for the establishment of these novel antibiotic therapies in routine clinical practice. [Orthopedics. 2018; 41(6):323-328.].

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.

Dalbavancin for treatment of implant-related methicillin-resistant Staphylococcus aureus osteomyelitis in an experimental rat model

Dalbavancin is a new semisynthetic lipoglycopeptide with improved antimicrobial activity against various gram-positive pathogens. It demonstrates an extensive plasma half-life which permits outpatient parenteral antimicrobial therapy with weekly intervals and might therefore be an excellent treatment alternative for patients requiring prolonged antimicrobial therapy. The present study investigated dalbavancin monotherapy in an experimental implant-related methicillin-resistant Staphylococcus aureus (MRSA) osteomyelitis model. A clinical MRSA isolate and a Kirschner-wire were inserted into the proximal tibia of anaesthetized Sprague-Dawley rats. Four weeks after infection 34 animals were treated over 4 weeks with either dalbavancin (20 mg/kg loading-dose; 10 mg/kg daily), vancomycin (50 mg/kg twice daily) or left untreated. Twenty-four hours after the last treatment dose tibial bones and Kirschner-wires were harvested for microbiological examination. Based on quantitative bacterial cultures of osseous tissue, dalbavancin was as effective as vancomycin and both were superior to no treatment. No emergence of an induced glycopeptide-/lipoglycopeptide- resistance was observed after a treatment period of four weeks with either dalbavancin or vancomycin. In conclusion, monotherapy with dalbavancin was shown to be as effective as vancomycin for treatment of experimental implant-related MRSA osteomyelitis in rats, but both antimicrobials demonstrated only limited efficacy. Further studies are warranted to evaluate the clinical efficacy of dalbavancin for the treatment of periprosthetic S. aureus infections.

In vitro activity of oritavancin against biofilms of staphylococci isolated from prosthetic joint infection

We tested the in vitro activity of oritavancin against 185 staphylococci associated with prosthetic joint infection, including 37 methicillin-resistant S. aureus, 67 methicillin-susceptible S. aureus, 59 methicillin-resistant S. epidermidis (MRSE), and 22 methicillin-susceptible S. epidermidis (MSSE) isolates. The oritavancin MIC₅₀ for S. aureus and MSSE was 0.03 μg/mL, and for MRSE, it was 0.06 μg/mL; MIC₉₀ for S. aureus and S. epidermidis was 0.12 μg/mL for both the methicillin-resistant and -susceptible subgroups. The oritavancin MBBC₅₀ for S. aureus and S. epidermidis was 2 μg/mL for both the methicillin-resistant and -susceptible subgroups; the MBBC₉₀ for S. aureus and MSSE was 4 μg/mL, and for MRSE, it was 8 μg/mL.

Dalbavancin is active in vitro against biofilms formed by dalbavancin-susceptible enterococci

We tested the in vitro activity of dalbavancin, vancomycin and daptomycin against 83 enterococcal isolates in planktonic and biofilm states. The MIC₉₀ for vancomycin-susceptible Enterococcus faecalis was 0.125 and 4μg/mL for dalbavancin and daptomycin, respectively. For vancomycin-resistant Enterococcus faecium, the MIC₉₀ was >16 and 2μg/mL for dalbavancin and daptomycin, respectively. Dalbavancin minimum biofilm inhibitory concentrations (MBICs) for vancomycin-susceptible and -resistant isolates were ≤0.25 and >16μg/mL, respectively. The daptomycin MBIC₉₀ for all isolates was 4μg/mL. For E. faecalis and E. faecium, dalbavancin minimum biofilm bactericidal concentrations (MBBCs) for vancomycin-susceptible and -resistant isolates were ≤4 and >16μg/mL, respectively, whereas vancomycin MBBCs were >128μg/mL for all isolates, and daptomycin MBBC₉₀ values for both species were 128μg/mL. In summary, dalbavancin exhibited in vitro activity against all tested isolates of vancomycin-susceptible, but not against vancomycin-resistant enterococci; activity was observed in both the planktonic and biofilm states.

Early recognition of methicillin-resistant Staphylococcus aureus surgical site infections using risk and protective factors identified by a group of Italian surgeons through Delphi method

BACKGROUND

Surgical site infections (SSIs) constitute a major clinical problem in terms of morbidity, mortality, duration of hospital stay, and overall costs. The bacterial pathogens implicated most frequently are Streptococcus pyogenes (S. pyogenes) and Staphylococcus aureus (S. aureus). The incidence of methicillin-resistant S. aureus (MRSA) SSIs is increasing significantly. Since these infections have a significant impact on hospital budgets and patients' health, their diagnosis must be anticipated and therapy improved. The first step should be to evaluate risk factors for MRSA SSIs.

METHODS

Through a literature review, we identified possible major and minor risk factors for, and protective factors against MRSA SSIs. We then submitted statements on these factors to 228 Italian surgeons to determine, using the Delphi method, the degree of consensus regarding their importance. The consensus was rated as positive if >80% of the voters agreed with a statement and as negative if >80% of the voters disagreed. In other cases, no consensus was reached.

RESULTS

There was positive consensus that sepsis, >2 weeks of hospitalization, age >75 years, colonization by MRSA, and diabetes were major risk factors for MRSA SSIs. Other possible major risk factors, on which a consensus was not reached, e.g., prior antibiotic use, were considered minor risk factors. Other minor risk factors were identified. An adequate antibiotic prophylaxis, laparoscopic technique, and infection committee surveillance were considered protective factors against MRSA SSIs. All these factors might be used to build predictive criteria for identifying SSI due to MRSA.

CONCLUSIONS

In order to help to recognize and thus promptly initiate an adequate antibiotic therapy for MRSA SSIs, we designed a gradation of risk and protective factors. Validation, ideally prospective, of this score is now required. In the case of a SSI, if the risk that the infection is caused by MRSA is high, empiric antibiotic therapy should be started after debriding the wound and collecting material for culture.