Genetic polymorphisms of TLR1, TLR2, TLR3 and TLR4 in patients with recurrent or severe infections

Toll-like receptors (TLRs) play an important role in innate immunity. Previous studies have shown that single nucleotide polymorphisms (SNPs) in the genes coding for these innate immune molecules can affect susceptibility to and the outcome of certain diseases. The aim of the present study was to examine the clinical relevance of well-studied TLR1-4 SNPs in individuals who are prone to infections. Four functional SNPs, TLR1 rs5743618 (1805C > A, Ser602Ile), TLR2 rs5743708 (2258G > A, Arg753Gln), TLR3 rs3775291 (1234C > T, Leu412Phe) and TLR4 rs4986790 (896A > G, Asp299Gly), were analysed in 155 patients with recurrent respiratory infections (n = 84), severe infections (n = 15) or common variable immunodeficiency (n = 56), and in 262 healthy controls, using the High Resolution Melting Analysis method. Polymorphisms of TLR2 rs5743708 (odds ratio [OR] 3.16; 95% confidence interval [CI] 1.45-6.83, p = .004, ap = .016) and TLR4 rs4986790 (OR 1.8; 95% CI 1.05-3.12, p = .028, ap = .112) were more frequent in patients with recurrent or severe infections than in controls. Interestingly, seven patients were found to carry both variant genotypes of TLR2 and TLR4, whereas none of the control group carried such genotypes (p  ≤ .0001). Moreover, TLR2 polymorphism was associated with increased risk for acute otitis media episodes (OR, 3.02; 95% CI 1.41-6.47; p = .012). This study indicates that children and adults who are more prone to recurrent or severe respiratory infections carry one or both variant types of TLR2 and TLR4 more often than control subjects. Genetic variations of TLRs help explain why some children are more susceptible to respiratory infections.

Association between hypogammaglobulinaemia and severe infections during induction therapy in ANCA-associated vasculitis: from J-CANVAS study

OBJECTIVES

To investigate the association between decreased serum IgG levels caused by remission-induction immunosuppressive therapy of antineutrophil cytoplasmic antibody-associated vasculitis (AAV) and the development of severe infections.

METHODS

We conducted a retrospective cohort study of patients with new-onset or severe relapsing AAV enrolled in the J-CANVAS registry, which was established at 24 referral sites in Japan. The minimum serum IgG levels up to 24 weeks and the incidence of severe infection up to 48 weeks after treatment initiation were evaluated. After multiple imputations for all explanatory variables, we performed the multivariate analysis using a Fine-Gray model to assess the association between low IgG (the minimum IgG levels <500 mg/dl) and severe infections. In addition, the association was expressed as a restricted cubic spline (RCS) and analysed by treatment subgroups.

RESULTS

Of 657 included patients (microscopic polyangiitis, 392; granulomatosis with polyangiitis, 139; eosinophilic granulomatosis with polyangiitis, 126), 111 (16.9%) developed severe infections. The minimum serum IgG levels were measured in 510 patients, of whom 77 (15.1%) had low IgG. After multiple imputations, the confounder-adjusted hazard ratio of low IgG for the incidence of severe infections was 1.75 (95% confidence interval: 1.03-3.00). The RCS revealed a U-shaped association between serum IgG levels and the incidence of severe infection with serum IgG 946 mg/dl as the lowest point. Subgroup analysis showed no obvious heterogeneity between treatment regimens.

CONCLUSION

Regardless of treatment regimens, low IgG after remission-induction treatment was associated with the development of severe infections up to 48 weeks after treatment initiation.

Severe Rickettsia typhi Infections, Costa Rica

Murine typhus is a febrile, fleaborne disease caused by infection with Rickettsia typhi bacteria. Cases can range from mild and nonspecific to fatal. We report 2 cases of murine typhus in Costa Rica, confirming the presence and circulation of R. typhi causing severe disease in the country.

Alternative Antimicrobial Irrigation Strategies for the Treatment of Infections in Children: A Review of the Existing Literature

As a synergistic treatment approach with systemic antimicrobial therapy or a systemic antibiotic-sparing strategy, the local administration of antimicrobial agents has been proposed as an alternative route for complicated infections. With the rationale of concentrating the active principle in the desired target site, avoiding potentially toxic systemic levels and bypassing anatomical and physiological barriers, local irrigation or infusion of antibiotics may effectively shorten the antimicrobial therapy course and reduce both infection-related and systemic therapy-related complications. Although evidence from the adult population supports its use in selected patients with an acceptable safety profile, data specifically focused on the pediatric population are limited. To provide a rapid and easily accessible tool for clinical practice, we synthesized the most relevant evidence on the use of local antimicrobial agents in common severe infections in children: meningitis, mediastinitis, pleural infections, recurrent urinary infections, and peritonitis. A literature search was performed using predefined combined keywords through an electronic research database (PubMed). Described molecules, dosages, routes, treated age groups, and related efficacy have been summarized for prompt application to clinical practice. It should, however, be noted that the evidence for the pediatric population remains limited, and the local administration of several molecules remains off-label. A careful multidisciplinary and patient-tailored evaluation, as well as a rational use of available guidelines, should always be the basis of clinical decision making in settings where local administration of antibiotics may be considered.

Corticosteroids Use and Incidence of Severe Infections in People Living with HIV Compared to a Matched Population

Background:

People living with HIV (PLWH) have been shown to have an increased risk of autoimmune diseases. Corticosteroids are the cornerstone of autoimmune diseases treatment, but their use is associated with an increased risk of infections. It is unclear how HIV status affects the risk of infection associated with corticosteroids use.

Methods:

We conducted a retrospective cohort study from 1991 to 2011, using a medico-administrative database from Quebec. Medical billing codes were used to identify PLWH, and we matched them on age, sex, and index date with up to 4 HIV-negative controls. The exposure of interest was the use of corticosteroids, defined as a systemic corticosteroid dispensation lasting at least 20 days. The outcome of interest was hospitalization for severe infection. Crude and adjusted incidence rates ratios of infection were obtained using a random effect Poisson model, and results were stratified by HIV status.

Results:

In total, 4798 PLWH were matched to 17 644 HIV-negative controls, among which 1083 (22.6%) PLWH and 1854 (10.5%) HIV-negative controls received at least one course of corticosteroid. The mean duration of corticosteroids use was 4 ± 4.4 months in PLWH and 1.6 ± 5.5 months in HIV-negative controls. The incidence rate ratio (IRR) for infections associated with corticosteroids use was 2.49[1.71–3.60] in PLWH and 1.32[0.71–2.47] in HIV-negative controls (P value for interaction 0.18). The most frequent infections were pulmonary infections (50.4%), followed by urinary tract infections (26%) and opportunistic infections (10.5%).

Conclusion:

Although our interaction term did not reach significance, the increased risk of infection associated with corticosteroids use was more pronounced in PLWH. However, further research with contemporary data is warranted to confirm if the risk associated with corticosteroids use remains high in PLWH with well-controlled HIV infection.

Severe Staphylococcus aureus infections in children: Case reports and management of positive Panton-Valentine leucocidin cases

BACKGROUND

Staphylococcus aureus is a well-known bacterium associated with carriage and responsible for different types of infections. The Panton-Valentine leucocidin (PVL) is a key virulence factor causing tissue necrosis. PVL can, however, be present in both benign and life-threatening infections.

CASE REPORTS AND MANAGEMENT

We present three pediatric severe infections occurring over a period of only three weeks, in February 2021, and caused by genetically unrelated methicillin-sensitive Staphylococcus aureus producing PVL in a tertiary children's hospital in Belgium. The first one presented with necrotizing pneumonia, the second one with a neck abscess extended to the mediastinum, and the last one had sacral osteomyelitis complicated by endocarditis. The management of these infections is mostly based on expert opinions. The most appropriate treatment seems to be the combination of early surgical drainage of infected collections with an antibiotic regimen associating two antibiotics; beta-lactams and either clindamycin or linezolid. Human immunoglobulins also appear to be useful as adjunctive therapy.

CONCLUSION

PVL-producing Staphylococcus aureus is associated with life-threatening infections in children. Prompt management is needed including surgery and appropriate antibiotic regimens.

Extended or Continuous Infusion of Carbapenems in Children with Severe Infections: A Systematic Review and Narrative Synthesis

We systematically reviewed the efficacy and safety of an extended or continuous infusion (EI/CI) versus short-term infusion (STI) of carbapenems in children with severe infections. Databases, including PubMed, Embase, the Cochrane Library, Clinicaltrials.gov, China National Knowledge Infrastructure, WanFang Data, and SinoMed, were systematically searched from their inceptions to 10 August 2020, for all types of studies (such as randomized controlled trials (RCTs), retrospective studies, and pharmacokinetic or population pharmacokinetic (PK/PPK) studies) comparing EI/CI versus STI in children with severe infection. There was no limitation on language, and a manual search was also conducted. The data were screened, evaluated, extracted, and reviewed by two researchers independently. Quantitative (meta-analysis) or qualitative analyses of the included studies were performed. Twenty studies (including two RCTs, one case series, six case reports, and 11 PK/PPK studies) were included in this review (CRD42020162845). The RCTs’ quality evaluation results revealed a risk of selection and concealment bias. Qualitative analysis of RCTs demonstrated that, compared with STI, an EI (3 to 4 h) of meropenem in late-onset neonatal sepsis could improve the clinical effectiveness and microbial clearance rates, and reduce the rates of mortality; however, the differences in the incidence of other adverse events were not statistically significant. Retrospective studies showed that children undergoing an EI of meropenem experienced satisfactory clinical improvement. In addition, the results of the PK/PPK study showed that an EI (3 or 4 h)/CI of carbapenems in severely infected children was associated with a more satisfactory goal achievement rate (probability of target attainment) and a cumulative fraction of response than STI therapy. In summary, the EI/CI of carbapenems in children with severe infection has a relatively sufficient PK or pharmacodynamic (PD) basis and satisfactory efficacy and safety. However, due to the limited quantity and quality of studies, the EI/CI therapy should not be used routinely in severely infected children. This conclusion should be further verified by more high-quality controlled clinical trials or observational studies based on PK/PD theories.

Novel Cephalosporins in Septic Subjects and Severe Infections: Present Findings and Future Perspective

In past decade, cephalosporins have developed significantly, and data regarding novel cephalosporins (i.e., ceftobiprole, ceftaroline, ceftolozane/tazobactam, ceftazidime/avibactam, and cefiderocol) within septic and bacteremic subjects are rising. These compounds generally offer very promising in vitro microbiological susceptibility, although the variability among gram-negative and -positive strains of different cohorts is noticed in the literature. We require further pharmacological data to measure the best dose in order to prevent sub-therapeutic drug levels in critically ill patients. These new compounds in theory are the sparing solution in the Enterobacteriales infection group for different antimicrobial classes such as aminoglycosides notably within endovascular and GNB-bacteremias, as well as colistin and carbapenem-sparing strategies, favoring good safety profile molecules. Moreover, new cephalosporins are the basis for the actual indications to open up new and exciting prospects for serious infections in the future. In future, patients will be addressed with the desirable approach to sepsis and serious infections in terms of their clinical situation, inherent features of the host, the sensitivity profile, and local epidemiology, for which evidence of the use of new cephalosporin in the treatment of severe infections will fill the remaining gaps.

Pre-hospital antibiotic therapy preceded by blood cultures in a physician-manned mobile emergency care unit

BACKGROUND

Rapid recognition and antibiotic treatment, preferably preceded by blood cultures (BCs), is a mainstay in sepsis therapy. The objective of this investigation was to determine if pre-hospital BCs were feasible and drawn with an acceptably low level of contamination and to investigate whether pre-hospital antibiotics were administered on correct indications.

METHODS

We performed a register-based study in a pre-hospital physician-manned mobile emergency care unit (MECU) operating in a mixed urban/rural area in Denmark. All patients who received pre-hospital antibiotics by the MECU from November 2013 to October 2018 were reviewed. Outcome measures were characterisation of microbial findings and subsequent in-hospital confirmation of the pre-hospital indication for antibiotics.

RESULTS

One-hundred-and-nineteen patients received antibiotics pre-hospitally. Six were excluded. One-hundred-and-thirteen patients were included in the study. BCs were drawn in 107 of the 113 patients (94.7% [88.8%-98.0%]). We found a true pathogen of sepsis in 29 (27.1% [19.0%-36.6%]) of these 107 patients. Nine (8.4% [3.9%-15.4%]) patients had contaminated pre-hospital BCs. Forty-nine of all patients (36.3% [27.4%-45.9%]) had causative pathogens in either their BCs or other samples confirming the pre-hospital tentative diagnosis. Eighty-two (72.6% [63.4%-80.5%]) patients received antibiotic therapy in-hospitally, while 27 (23.9% [16.4%-32.8%]) were assigned an in-hospital diagnosis not associated with infection. Four (3.5% [1.0%-8.8%]) patients died in hospital before a diagnosis was established.

CONCLUSIONS

Pre-hospital administration of antibiotics preceded by BCs is feasible, although with somewhat high blood culture contamination rates. Antibiotics are administered on reasonable indications.

Severe infections in patients with ANCA associated vasculitis treated with rituximab

BACKGROUND AND OBJECTIVES

Rituximab (RTX) is an anti-CD20 antibody that selectively depletes B-cells and has emerged as a therapy for ANCA-associated vasculitis (AAV) during the past decade. This study sought to quantify, and determine potential risk factors for, severe infections in AAV patients treated with RTX at rheumatology clinics in Mexico City, Mexico and Lund, Sweden.

METHODS

The study consisted of a retrospective case-record review (2005-2015) with standardized data collection related to the occurrence of severe infection in 46 patients with AAV in Mexico City (n = 20) and Lund (n = 26) treated with RTX during their disease course. Median duration of follow-up from first RTX dose to death or end of study was 26 months.

RESULTS

Eleven (24%) patients suffered a total of 18 severe infections (infection rate of 11.5/100 patient-years). Thirteen of the 18 infections (72%) occurred within the first year of treatment. Risk factors for severe infection were older age at RTX initiation and absence of ENT-involvement at diagnosis. In multivariate analyses, age at RTX infusion was the only independent factor predicting severe infection. Four patients (9%) died during follow-up, all as a result of infection.

CONCLUSIONS

Severe infections are common following RTX treatment, and mortality due to infection is a major concern. Most severe infections occur within the first year of RTX treatment. The negative correlation of ENT involvement with severe infection might reflect GPA phenotype heterogeneity. Older age at time of RTX treatment independently predicts severe infections.

A Systematic Review of the Effect of Delayed Appropriate Antibiotic Treatment on the Outcomes of Patients With Severe Bacterial Infections

BACKGROUND

Patients with severe bacterial infections often experience delay in receiving appropriate treatment. Consolidated evidence of the impact of delayed appropriate treatment is needed to guide treatment and improve outcomes.

RESEARCH QUESTION

What is the impact of delayed appropriate antibacterial therapy on clinical outcomes in patients with severe bacterial infections?

STUDY DESIGN AND METHODS

Literature searches of MEDLINE and Embase, conducted on July 24, 2018, identified studies published after 2007 reporting the impact of delayed appropriate therapy on clinical outcomes for hospitalized adult patients with bacterial infections. Where appropriate, results were pooled and analyzed with delayed therapy modeled three ways: delay vs no delay in receiving appropriate therapy; duration of delay; and inappropriate vs appropriate initial therapy. This article reports meta-analyses on the effect of delay and duration of delay.

RESULTS

The eligibility criteria were met by 145 studies, of which 37 contributed data to analyses of effect of delay. Mortality was significantly lower in patients receiving appropriate therapy without delay compared with those experiencing delay (OR, 0.57; 95% CI, 0.45-0.72). Mortality was also lower in the no-delay group compared with the delay group in subgroups of studies reporting mortality at 20 to 30 days, during ICU stay, or in patients with bacteremia (OR, 0.57 [95% CI, 0.43-0.76]; OR, 0.47 [95% CI, 0.27-0.80]; and OR, 0.54 [95% CI, 0.40-0.75], respectively). No difference was found in time to appropriate therapy between those who died and those who survived (P = .09), but heterogeneity between studies was high.

INTERPRETATION

Avoiding delayed appropriate therapy is essential to reduce mortality in patients with severe bacterial infections.

CLINICAL TRIAL REGISTRATION

PROSPERO; No.: CRD42018104669; URL: www.crd.york.ac.uk/prospero/.

Critical Parameters for the Development of Novel Therapies for Severe and Resistant Infections-A Case Study on CAL02, a Non-Traditional Broad-Spectrum Anti-Virulence Drug

Background: Poor outcomes in severe and resistant infections, together with the economic struggles of companies active in the field of anti-infective development, call for new solutions and front runners with novel approaches. Among “non-traditional” approaches, blocking virulence could be a game changer. Objectives: This review offers a perspective on parameters that have determined the development path of CAL02, a novel anti-virulence agent, with a view to steering clear of the obstacles and limitations that impede market sustainability for new anti-infective drugs. Conclusions and implications of key findings: This case study highlights four pillars that may support the development of other non-traditional drugs and, concurrently, provide a new model that could reshape the field. Therapeutic triggers, study designs, and economic parameters are discussed.

Infection-induced innate antimicrobial response disorders: from signaling pathways and their modulation to selected biomarkers

Severe infections are a major public health problem responsible for about 40-65% of hospitalizations in intensive care units (ICU). The high mortality (30-50%) of persons diagnosed with severe infection is caused by largely unknown mechanisms of sepsis-induced immune system response. Severe infections with dynamic progress are accompanied with SIRS (systemic inflammatory reaction syndrome) and CARS (compensatory anti-inflammatory response syndrome), and require a biological treatment appropriate to the phase of immune response. The mechanisms responsible for severe infection related to immune system response particularly attract extensive interest of non-specific defense mechanisms, including signaling pathways of Toll-like receptors (mainly TLR4 and TLR2) that recognize distinct pathogen-associated molecular patterns (PAMP) and play a critical role in innate immune response. There are attempts of treatment, followed by blocking ligand binding with TLR or modulation of intracellular signaling pathways, to inhibit signal transduction. Moreover, researches regarding new and more efficient diagnostics biomarkers were mostly focused on indicators related to innate response to infection as well as connections of pro-inflammatory response with anti-inflammatory response.According to these studies, in case of ICU septic patients with high-risk of mortality, the solution for the problem will require mainly early immune and genetic diagnostics (e.g. cytokines, microRNA, cluster of differentiation-64 [CD64], triggering receptor expressed on myeloid cells-1 [TREM-1], and high mobility group box 1 protein [HMGB1]).

Clinical correlates and outcomes in a group of Puerto Ricans with systemic lupus erythematosus hospitalized due to severe infections

Objective

Infections are a major cause of morbidity and mortality in systemic lupus erythematosus. Clinical outcomes of systemic lupus erythematosus patients hospitalized due to infections vary among different ethnic populations. Thus, we determined the outcomes and associated factors in a group of Hispanics from Puerto Rico with systemic lupus erythematosus admitted due to severe infections.

Methods

Records of systemic lupus erythematosus patients admitted to the Adult University Hospital, San Juan, Puerto Rico, from January 2006 to December 2014 were examined. Demographic parameters, lupus manifestations, comorbidities, pharmacologic treatments, inpatient complications, length of stay, readmissions, and mortality were determined. Patients with and without infections were compared using bivariate and multivariate analyses.

Results

A total of 204 admissions corresponding to 129 systemic lupus erythematosus patients were studied. The mean (standard deviation) age was 34.7 (11.6) years; 90% were women. The main causes for admission were lupus flare (45.1%), infection (44.0%), and initial presentation of systemic lupus erythematosus (6.4%). The most common infections were complicated urinary tract infections (47.0%) and soft tissue infections (42.0%). In the multivariate analysis, patients admitted with infections were more likely to have diabetes mellitus (odds ratio: 4.20, 95% confidence interval: 1.23-14.41), exposure to aspirin prior to hospitalization (odds ratio: 4.04, 95% confidence interval: 1.03-15.80), and higher mortality (odds ratio: 6.00, 95% confidence interval: 1.01-35.68) than those without infection.

Conclusion

In this population of systemic lupus erythematosus patients, 44% of hospitalizations were due to severe infections. Patients with infections were more likely to have diabetes mellitus and higher mortality. Preventive and control measures of infection could be crucial to improve survival in these patients.

Successful treatment of three severe MDR or XDR Pseudomonas aeruginosa infections with ceftolozane/tazobactam

Ceftolozane/tazobactam is a novel fifth-generation cephalosporin β-lactamase combination with activity against extended-spectrum β-lactamases-producing enterobacteriaceae, and multidrug resistant Pseudomonas aeruginosa. However, clinical experience in real cases caused by these microorganisms is scarce. In this study, we describe three patients with severe infections caused by multidrug resistant and extensively drug-resistant (XDR) P. aeruginosa that were successfully treated with ceftolozane/tazobactam.

Population Pharmacokinetics of Tigecycline in Critically Ill Patients with Severe Infections

We sought to describe the population pharmacokinetics of tigecycline in critically ill patients and to determine optimized dosing regimens of tigecycline for different bacterial infections. This prospective study included 10 critically ill patients given a standard dose of tigecycline. Blood samples were collected during one dosing interval and were analyzed using validated chromatography. Population pharmacokinetics and Monte Carlo dosing simulations were undertaken using Pmetrics. Three target exposures, expressed as ratios of the 24-h area under the curve to MICs (AUC_0-24/MIC), were evaluated (≥17.9 for skin infections, ≥6.96 for intra-abdominal infections, ≥4.5 for hospital-acquired pneumonia). The median age, total body weight, and body mass index (BMI) were 67 years, 69.1 kg, and 24.7 kg/m², respectively. A two-compartment linear model best described the time course of tigecycline concentrations. The parameter estimates (expressed as means ± standard deviations [SD]) from the final model were as follows: clearance (CL), 7.50 ± 1.11 liters/h; volume in the central compartment, 72.50 ± 21.18 liters; rate constant for tigecycline distribution from the central to the peripheral compartment, 0.31 ± 0.16 h^-1; and rate constant for tigecycline distribution from the peripheral to the central compartment, 0.29 ± 0.30 h^-1 A larger BMI was associated with increased CL of tigecycline. Licensed doses were found to be sufficient for Enterobacter cloacae, Escherichia coli, Klebsiella pneumoniae, and methicillin-resistant Staphylococcus aureus for an AUC_0-24/MIC target of 4.5 or 6.96. For a therapeutic target of 17.9, an increased tigecycline dose is required, especially for patients with higher BMI. The dosing requirements of tigecycline differ with the indication, with pathogen susceptibility, and potentially with patient BMI.

Severe infections after single umbilical cord blood transplantation in adults with or without the co-infusion of CD34+ cells from a third-party donor: results of a multicenter study from the Grupo Español de Trasplante Hematopoyético (GETH)

BACKGROUND

Umbilical cord blood transplantation (CBT) is an established alternative source of stem cells in the setting of unrelated transplantation. When compared with other sources, single-unit CBT (sCBT) is associated with a delayed hematologic recovery, which may lead to a higher infection-related mortality (IRM). Co-infusion with the sCBT of CD34+ peripheral blood stem cells from a third-party donor (TPD) (sCBT + TPDCD34+) has been shown to markedly accelerate leukocyte recovery, potentially reducing the IRM. However, to our knowledge, no comparative studies have focused on severe infections and IRM with these 2 sCBT strategies.

METHODS

A total of 148 consecutive sCBT (2000-2010, median follow-up 4.5 years) were included in a multicenter retrospective study to analyze the incidence and risk factors of IRM and severe viral and invasive fungal infections (IFIs). Neutrophil engraftment occurred in 90% of sCBT (n = 77) and 94% sCBT + TPDCD34+ (n = 71) recipients at a median of 23 and 12 days post transplantation, respectively (P < 0.01).

RESULTS

The 4-year IRM was 24% and 20%, respectively (P = 0.7), with no differences at day +30 (5% and 4%, respectively) and day +100 (10% and 8%, respectively). In multivariate analysis early status of the underlying malignancy, cytomegalovirus (CMV)-seronegative recipient and high CD34+ cell content in the cord blood unit before cryostorage (≥1.4 × 10(5) /kg) were protective of IRM. Among the causes of IRM, bacterial infections and IFIs were more common in sCBT (15% vs. 4%), while CMV disease and parasitic infections were more common in the sCBT + TPDCD34+ cohort (5% vs. 16%).

CONCLUSION

These data show that sCBT supported with TPDCD34(+) cells results in much shorter periods of post-transplant leukopenia, but the short- and long-term rates of IRM were comparable to those of sCBT, presumably because immune recovery is equally delayed in both graft types.

Liposomal co-delivery of daptomycin and clarithromycin at an optimized ratio for treatment of methicillin-resistant Staphylococcus aureus infection

CONTEXT

Pathogen evolution currently outpaces novel drug development, and because development of new antibiotics is pending, combination therapy with existing drugs may provide effective alternative treatments.

OBJECTIVE

The present study was aimed at evaluating the concurrent use of two antibiotics, daptomycin and clarithromycin, against methicillin-resistant Staphylococcus aureus (MRSA) infections.

MATERIALS AND METHODS

Polyeythylene glycol (PEGylated liposomes loaded with daptomycin, clarithromycin, or both (PL[CD]) at an optimized mass ratio of 1:32 were generated and characterized using dynamic light scattering and electron microscopy. In vitro and in vivo approaches were used to compare liposome effects on MRSA.

RESULTS

PL[CD] were stable, with a mean (± SD) vesicle diameter of 98.2 ± 2.21 nm and encapsulation efficiency of 94.71 ± 1.37% (daptomycin) and 92.94 ± 1.21% (clarithromycin). Compared with daptomycin-only liposomes, PL[CD] showed significantly enhanced anti-MRSA activity in vitro and significantly reduced MRSA bacterial load and increased host survival in vivo.

DISCUSSION

Co-delivery of daptomycin with clarithromycin produced significant anti-MRSA activity in the presence of only one-thirtieth of the concentration required in liposomes containing daptomycin only.

CONCLUSION

These findings suggested that concurrent liposomal delivery of daptomycin and clarithromycin has the potential to be an effective and less toxic treatment for MRSA infections.