The safety and efficacy of high-dose daptomycin combined with rifampicin for the treatment of Gram-positive osteoarticular infections

Comparison of daptomycin and glycopeptide efficacy and safety for the treatment of Gram-positive infections: a systematic review and meta-analysis

BACKGROUND

The indications of daptomycin have been extended to off-label indications including prosthesis-related infection, and bone and joint infection (BJI). However, efficacy and safety have not been thoroughly demonstrated compared with the standard of care. This systematic review and meta-analysis aimed to compare the treatment effect of daptomycin and glycopeptides for complicated infections.

MATERIALS AND METHODS

MEDLINE, Embase and Web of Science were searched for randomized controlled trials (RCTs) comparing daptomycin and standard of care for Gram-positive infections, published until 30 June 2021. The primary outcome was defined as all-cause mortality. Secondary outcomes were clinical and microbiological success. The main safety outcome was any severe adverse event (SAE) (grade  ≥3).

RESULTS

Overall, eight RCTs were included in the meta-analysis, totalling 1095 patients. Six (75%) were in complicated skin and soft-structure infections, one (12.5%) in bacteraemia and one (12.5%) in a BJI setting. Six RCTs used vancomycin as a comparator and two used either vancomycin or teicoplanin. All-cause mortality and clinical cure were not different between groups. The microbiological cure rate was superior in patients who received daptomycin [risk ratio (RR) = 1.17 (95% CI: 1.01-1.35)]. The risk of SAEs [RR = 0.57 (95% CI: 0.36-0.90)] was lower in the daptomycin arm.

CONCLUSIONS

While daptomycin is associated with a significantly lower risk of SAEs and a better microbiological eradication, substantial uncertainty remains about the best treatment strategy in the absence of good-quality evidence, especially in bacteraemia and endocarditis where further RCTs should be conducted.

Daptomycin-Rifampin-Induced Rhabdomyolysis, Acute Renal Failure, and Hepatic Injury: A Case Report and Literature Review

Daptomycin is a canonical antibiotic used very commonly in practice for its bactericidal activity against Gram-positive bacteria, including vancomycin-resistant enterococci (VRE) and methicillin-resistant Staphylococcus aureus (MRSA) bacteremia, bone infections, skin and soft tissue infections, meningitis, urinary tract infections, and endocarditis. Although daptomycin in conventional doses is usually well tolerated, it is paramount to be aware of the possible adverse effects. Daptomycin is reported to cause an elevation in creatine kinase levels, although frank rhabdomyolysis is rare. An even more infrequent occurrence is the simultaneous development of acute kidney injury and drug-induced liver injury with rhabdomyolysis. Daptomycin and rifampin combination are used for synergistic bactericidal action against MRSA. Still, data on the efficacy and safety of the combination is limited due to a lack of extensive studies. Herein, we present a clinical case of septic arthritis of a prosthetic knee, which resulted in bacteremia caused by methicillin-resistant Staphylococcus aureus (MRSA) and subsequently led to infective endocarditis of the aortic valve. The patient was treated with a combination of daptomycin and rifampin, complicated by the development of rhabdomyolysis, acute kidney injury, and drug-induced liver injury. This case highlights the significance of timely recognizing adverse drug effects and identifying risk factors to ensure successful patient outcomes.

Does a New Antibiotic Scheme Improve the Outcome of Staphylococcus aureus-Caused Acute Prosthetic Joint Infections (PJI) Treated with Debridement, Antibiotics and Implant Retention (DAIR)?

One of the most commonly used treatments for acute prosthetic joint infection (PJI) is DAIR (debridement, antibiotics and implant retention), which comprises the debridement and the retention of the implant, followed by antibiotic treatment. The efficacy of DAIR remains unclear, as the literature has demonstrated variable success rates, ranging from 26% to 92%. The Staphylococcus aureus is one of the most closely related causative microorganisms, especially with acute and late-acute PJI; it has been identified as one of the most significant predictors of DAIR failure. The current guidelines consider the use of vancomycin as the therapy of choice, but it requires the close control of possible side effects. The aim of this study is to determine if a new combination of antibiotics (a highly bactericidal initial combination followed by an antibiofilm scheme) decreases the failure of DAIR-treated acute prosthetic joint infection (PJI) caused by Staphylococcus aureus. A retrospective analysis of cases of orthopedic infections during a nine-year period (2011–2019) was performed. A total of 45 acute PJI cases caused by S. aureus were diagnosed. The results of two antibiotic schemes were compared: a novel scheme comprising 5 days of daptomycin (10 mg/kg/24 h) + cloxacillin (2 g/6 h) followed by levofloxacin (500 mg/24 h) + rifampicin (600 mg/24 h), versus a traditional, less bactericidal scheme of vancomycin (1000 mg/12 h) plus rifampicin (600 mg/24 h) or levofloxacin (500 mg/24 h) plus rifampicin (600 mg/24 h). Twenty-two out of the twenty-four patients treated with the new scheme (91.6%) were free of infection after 24.8 months of mean follow-up, whereas fourteen out of twenty-one patients (66.6%) were free of infection after 46.6 months of follow-up. This difference was statistically significant (p = 0.036). Demographic comparisons demonstrated homogeneous features, except the Charlson score, which was higher in the novel scheme group (p = 0.047). The combination of high-dose daptomycin and cloxacillin, followed by levofloxacin plus rifampicin, together with surgical treatment, shows better results when compared with other antibiotic schemes for treating acute PJI caused by S. aureus in which DAIR was performed.

Association between statin use and daptomycin-related musculoskeletal adverse events: A mixed approach combining a meta-analysis and a disproportionality analysis

Background

There is a growing concern about the association between the combined use of daptomycin (DAP) and statins and the occurrence of musculoskeletal adverse events (MAEs), but this remains controversial. This study aimed to clarify the association between statin use and DAP-related MAEs.

Methods

We used a mixed approach that combines 2 methodologies. First, we conducted a meta-analysis to examine the effects of statin use on DAP-related MAEs. Second, we conducted a disproportionality analysis using the US Food and Drug Administration Adverse Events Reporting System (FAERS) to further confirm the results of the meta-analysis and to examine the effect of each type of statin on DAP-related MAEs in a large population.

Results

In the meta-analysis, statin use significantly increased the incidence of DAP-related rhabdomyolysis (odds ratio [OR]: 3.83; 95% confidence interval [CI]: 1.43–10.26) but not DAP-related myopathy (OR: 1.72; 95% CI: .95–3.12). In the disproportionality analysis using the FAERS, the use of statin significantly increased the reporting OR (ROR) for DAP-related myopathy (ROR: 5.69; 95% CI: 4.31–7.51) and rhabdomyolysis (ROR: 5.77; 95% CI: 4.33–7.68). Atorvastatin, rosuvastatin, and simvastatin all increased the incidence of DAP-related myopathy and rhabdomyolysis.

Conclusion

The mixed approach combining a meta-analysis and disproportionality analysis showed that statin use was associated with the occurrence of DAP-related rhabdomyolysis. The appropriate use of statins and DAP should be performed with careful consideration of its safety.

Daptomycin for the Treatment of Gram-Positive Periprosthetic Hip Infections: Can Daptomycin Prevent the Implant Removal?

Introduction

Management of periprosthetic hip infections (PHIs) generally consists of implant removal and thorough debridement, accompanied by appropriate antibiotic therapy. Daptomycin (DAP) is a novel antibiotic, which allowed for implant retention in several patients after treating their infected joints. However, there is no consensus about implant retention or removal during the treatment of PHIs. The aim of this study was to examine the effect of DAP and to determine a surgical treatment strategy.

Methods

This study retrospectively evaluated 20 patients between August 2014 and December 2018, divided into implant retention (n=9) and implant removal groups (n=11). Infection control and risk of recurrent infection were evaluated. Infection control was defined as not requiring implant removal after the final treatment.

Results

Infection control rates in implant retention and implant removal groups were 67% and 90%, respectively. All late chronic infections resulted in failure cases within the implant retention group. In the implant retention group, mean preoperative risk scores for successful cases were significantly higher than those for failure cases (p<0.05).

Conclusions

Patients with low risk did not require implant removal, suggesting that DAP may be a breakthrough alternative to traditional PHI management.

Osteoarticular infections: a specific program for older patients?

BACKGROUND

With the increasing number of elderly patients, arthroplasties, fractures and diabetic foot infections, the worldwide number of osteoarticular infections (OAI) among the elderly is concomitantly expected to rise.

AIMS

We explore existing scientific knowledge about OAI in the frail elderly population.

METHODS

We performed a literature search linking OAIs to geriatric patients and comparing elderly patients (> 65 years) with average adults (range 18-65 years).

RESULTS

In this literature, financial aspects, comparison of diverse therapies on quality of life, reimbursement policies, or specific guidelines or nursing recommendations are missing. Age itself was not an independent factor related to particular pathogens, prevention of OAI, nursing care, and outcomes of OAI. However, geriatric patients were significantly more exposed to adverse events of therapy. They had more co-morbidities and more conservative surgery for OAI.

CONCLUSION

Available literature regarding OAI management among elderly patients is sparse. In recent evaluations, age itself does not seem an independent factor related to particular epidemiology, pathogens, prevention, nursing care, rehabilitation and therapeutic outcomes of OAI. Future clinical research will concern more conservative surgical indications, but certainly reduce inappropriate antibiotic use.

High-Dose Daptomycin and Clinical Applications

OBJECTIVE

To evaluate evidence for high-dose daptomycin (doses ≥ 8 mg/kg/d).

DATA SOURCES

A PubMed/MEDLINE literature search was performed (January 2000 to December 2020) using the search terms daptomycin, high dose, and dosing. Review article references and society guidelines were reviewed.

STUDY SELECTION AND DATA EXTRACTION

Clinical trials, observational studies, retrospective studies, meta-analyses, and systematic reviews reporting on high-dose daptomycin were included.

DATA SYNTHESIS

Experimentally, daptomycin outperforms other antimicrobials for high inoculum and biofilm-associated infections. Clinically, high-dose daptomycin is supported as salvage and first-line therapy for endocarditis and bacteremia, primarily when caused by methicillin-resistant Staphylococcus aureus (when vancomycin minimum inhibitory concentration is >1 mg/L) and Enterococcus. High-dose daptomycin appears effective for osteomyelitis and central nervous system infections, although comparative studies are lacking. High dosing in renal replacement therapy requires considering clearance modality to achieve exposures like normal renal function. Weight-based dosing in obesity draws concern for elevated exposures, although high doses have not been evaluated kinetically in obesity. Some data show benefits of high doses in overweight populations. Burn patients clear daptomycin more rapidly, and high doses may only achieve drug exposures similar to standard doses (6 mg/kg).

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

This review analyzes the efficacy and safety of high-dose daptomycin in serious gram-positive infections. Discussion of specific infectious etiologies and patient populations should encourage clinicians to evaluate their daptomycin dosing standards.

CONCLUSIONS

The efficacy of high-dose daptomycin and limited safety concerns encourage clinicians to consider high-dose daptomycin more liberally in severe gram-positive infections.

The First Report on Pharmacokinetic/Pharmacodynamic Study of Trimethoprim/Sulfamethoxazole against Staphylococcus aureus with a Neutropenic Murine Thigh Infection Model

INTRODUCTION

With an increase in the incidence of Staphylococcus aureus infections in the healthcare settings and in the community, trimethoprim/sulfamethoxazole (TMP/SMX) has been suggested as a convenient treatment option. However, the appropriate dosage regimen of TMP/SMX is unclear.

OBJECTIVE

This study aimed to examine the pharmacokinetics/pharmacodynamics (PK/PD) of TMP/SMX against S. aureus using a neutropenic murine thigh infection model.

METHODS

Five S. aureus isolates with TMP/SMX (1:5 fixed ratio) minimum inhibitory concentrations (MICs) of 0.032-64 μg/mL were tested. The antimicrobial efficacy of TMP/SMX (1-689 mg/kg/day: dose shown as SMX dosage) was calculated as the change in bacterial density after 24 h of treatment. The plasma concentrations of TMP/SMX were detected using high-performance liquid chromatography.

RESULTS

After TMP/SMX single dose (130 mg/kg), the half-life, area under the blood concentration curve (AUC0-∞), and the protein binding ratio of SMX were 1.5 h, 718.2 μg h/mL, and 73.0 ± 8.3%, respectively. The free AUC/MIC and free %time (%T) above the MIC of SMX were better correlated with the in vivo antimicrobial activity than Cmax/MIC (free AUC/MIC, R2 = 0.69; free %T > MIC, R2 = 0.71; free Cmax/MIC, R2 = 0.53). The distributed doses (2-3 times per day) of TMP/SMX (130, 260, and 390 mg/kg/day) showed higher antimicrobial activity than the single dosage. However, TMP/SMX did not show its antimicrobial activity at <100% free %T > MIC.

CONCLUSIONS

The TMP/SMX treatment demonstrated that the free AUC/MIC of SMX was the better predictor of the PK/PD index of TMP/SMX.

Changing perioperative prophylaxis during antibiotic therapy and iterative debridement for orthopedic infections?

Background

Perioperative antibiotic prophylaxis in non-infected orthopedic surgery is evident, in contrast to prophylaxis during surgery for infection. Epidemiological data are lacking for this particular situation.

Methods and findings

It is a single-center cohort on iterative surgical site infections (SSIs) in infected orthopedic patients. We included 2480 first episodes of orthopedic infections (median age 56 years and 833 immune-suppressed): implant-related infections (n = 648), osteoarticular infections (1153), and 1327 soft tissue infections. The median number of debridement was 1 (range, 1–15 interventions). Overall, 1617 infections (65%) were debrided once compared to 862 cases that were operated multiple times (35%). Upon iterative intraoperative tissue sampling, we detected pathogens in 507 cases (507/862; 59%), of which 241 (242/507; 48%) corresponded to the initial species at the first debridement. We witnessed 265 new SSIs (11% of the cohort) that were resistant to current antibiotic therapy in 174 cases (7% of the cohort). In multivariate analysis, iterative surgical debridements that were performed under current antibiotic administration were associated with new SSIs (odds ratio 1.6, 95%CI 1.2–2.2); mostly occurring after the 2^nd debridement. However, we failed to define an ideal hypothetic prophylaxis during antibiotic therapy to prevent further SSIs.

Conclusions

Selection of new pathogens resistant to ongoing antibiotic therapy occurs frequently during iterative debridement in orthopedic infections, especially after the 2^nd debridement. The new pathogens are however unpredictable. The prevention, if feasible, probably relies on surgical performance and wise indications for re-debridement instead of new maximal prophylactic antibiotic coverage in addition to current therapeutic regimens.

Daptomycin to bone and joint infections and prosthesis joint infections: a systematic review

Backgroud

Daptomycin has been used in bone and joint infections (BJI) and prosthesis joint infections (PJI) considering spectrum of activity and biofilm penetration. However, the current experience is based on case reports, case series, cohorts, and international surveys. The aim of this systematic review was to evaluate studies about daptomycin treatment efficacy in BJI/PJI compared to other antibiotic regimens.

Methods

PubMed, LILACS, Scielo and Web of Science databases were searched for articles about daptomycin and treatment of BJI and PJI from inception to March 2018. Inclusion criteria were any published researches that included patients with BJI treated with daptomycin. Diagnosis of BJI was based on clinical, laboratory and radiological findings according to IDSA guidelines.

Results

From 5107 articles, 12 articles were included. Only three studies described the outcomes of patients with BJI treated with daptomycin with comparator regimen (vancomycin, teicoplanin and oxacillin). Studies presented large heterogeneity regarding device related infections, surgical procedures, and daptomycin regimens (varied from 4 mg/kg to 10 mg/kg). A total of 299 patients have been included in all studies (184 infections associated with orthopedic disposal and 115 osteomyelitis/septic arthritis). Two hundred and thirty-three patients were treated with daptomycin. The clinical cure rates on device related and non-device related infections (i.e. osteomyelitis) were 70% and 78%, respectively. Compared to all regimens evaluated, daptomycin group outcomes were non-inferior.

Conclusion

Although a randomized clinical trial is needed, this systematic review tends to support daptomycin usage for bone and joint infections.

The Benefice of Mobile Parts' Exchange in the Management of Infected Total Joint Arthroplasties with Prosthesis Retention (DAIR Procedure)

Background: The management of prosthetic joint infections (PJI) with debridement and retention of the implant (DAIR) has its rules. Some authors claim that lacking the exchange of mobile prosthetic parts is doomed to failure, while others regard it as optional. Methods: Single-center retrospective cohort in PJIs treated with DAIR. Results: We included 112 PJIs (69 total hip arthroplasties, 9 medullary hip prostheses, 41 total knee arthroplasties, and 1 total shoulder arthroplasty) in 112 patients (median age 75 years, 52 females (46%), 31 (28%) immune-suppressed) and performed a DAIR procedure in all cases-48 (43%) with exchange of mobile parts and 64 without. After a median follow-up of 3.3 years, 94 patients (84%) remained in remission. In multivariate Cox regression analysis, remission was unrelated to PJI localization, pathogens, number of surgical lavages, duration of total antibiotic treatment or intravenous therapy, choice of antibiotic agents, immune-suppression, or age. In contrast, the exchange of mobile parts was protective (hazard ratio 1.9; 95% confidence interval 1.2⁻2.9). Conclusions: In our retrospective single-center cohort, changing mobile parts of PJI during the DAIR approach almost doubled the probability for long-term remission.

Factors associated with development of nephrotoxicity in patients treated with vancomycin versus daptomycin for severe Gram-positive infections: A practice-based study

OBJECTIVE

To evaluate nephrotoxicity development in patients treated with vancomycin (VAN) and daptomycin (DAP) for proven severe Gram-positive infections in daily practice.

METHODS

A practice-based, observational, retrospective study (eight Spanish hospitals) was performed including patients ≥18 years with a baseline glomerular filtration rate (GFR)>30 mL/min and/or serum creatinine level<2 mg/dL treated with DAP or VAN for >48h. Nephrotoxicity was considered as a decrease in baseline GRF to <50 mL/min or decrease of >10 mL/min from a baseline GRF<50 mL/min. Multivariate analyses were performed to determine factors associated with 1) treatment selection, 2) nephrotoxicity development, and 3) nephrotoxicity development within each antibiotic group.

RESULTS

A total of 133 patients (62 treated with DAP, 71 with VAN) were included. Twenty-one (15.8%) developed nephrotoxicity: 4/62 (6.3%) patients with DAP and 17/71 (23.3%) with VAN (p=0.006). No differences in concomitant administration of aminoglycosides or other potential nephrotoxic drugs were found between groups. Factors associated with DAP treatment were diabetes mellitus with organ lesion (OR=7.81, 95%CI:1.39-4.35) and basal creatinine ≥0.9 mg/dL (OR=2.53, 95%CI:1.15-4.35). Factors associated with VAN treatment were stroke (OR=7.22, 95%CI:1.50-34.67), acute myocardial infarction (OR=6.59, 95%CI:1.51-28.69) and primary bacteremia (OR=5.18, 95%CI:1.03-25.99). Factors associated with nephrotoxicity (R2=0.142; p=0.001) were creatinine clearance<80 mL/min (OR=9.22, 95%CI:1.98-30.93) and VAN treatment (OR=6.07, 95%CI:1.86-19.93). Factors associated with nephrotoxicity within patients treated with VAN (R2=0.232; p=0.018) were congestive heart failure (OR=4.35, 95%CI:1.23-15.37), endocarditis (OR=7.63, 95%CI:1.02-57.31) and basal creatinine clearance<80 mL/min (OR=7.73, 95%CI:1.20-49.71).

CONCLUSIONS

Nephrotoxicity with VAN was significantly higher than with DAP despite poorer basal renal status in the DAP group.

Polymicrobial anaerobic infection with a deep abscess in the supraspinous fossa following a subacromial corticosteroid injection

In September 2015, a male aged 61 years with poorly controlled diabetes (his only medical problem) had left shoulder surgery that included an arthroscopic acromioplasty with debridement of suture material from a rotator cuff repair done 10 years prior. A subacromial corticosteroid injection was given 7 months later for pain and reduced motion. Three weeks later a fulminate infection was evident. Cultures grew Propionibacterium acnes. Treatment included two arthroscopic debridement surgeries and 8 weeks of intravenous antibiotics (primarily daptomycin). Eight weeks after the cessation of the antibiotics, purulence recurred and tissue cultures then grew Staphylococcus epidermidis. Several additional surgeries were needed to control the infection. We failed to recognise that an abscess that extended from the subacromial space across the entire supraspinous fossa. We report this case to alert clinicians that a seemingly innocuous subacromial corticosteroid injection can lead to an atypical infection and also extend into the supraspinous fossa.

Should antibiotic prophylaxis before orthopedic implant surgery depend on the duration of pre-surgical hospital stay?

Background

Prolonged hospital stay before surgery is a risk for colonization with antibiotic-resistant microorganisms and possible antibiotic-resistant surgical site infections (SSI), which lacks acknowledgement in international guidelines for perioperative antibiotic prophylaxis.

Method

Retrospective cohort study focusing on prophylaxis-resistant SSI in adult orthopedic implant patients; with emphasis on length of hospital stay prior to the index surgery.

Results

We enrolled 611 cases of SSI (median age, 65 years; 241 females and 161 immune-suppressed) in four large implant groups: arthroplasties (n = 309), plates (n = 127), spondylodeses (n = 31), and nails (n = 46). The causative pathogen was resistant to the perioperative antibiotic prophylaxis regimen in 307 cases (307/611; 50%), but the length of pre-surgical hospitalization did not influence the incidences of prophylaxis-resistant SSIs. These incidences were (107/211;51%) for the admission day, (170/345;49%) within 10 days of delay, (19/35;54%) between 10 and 20 days, and (11/20; 55%) beyond 20 days of hospital stay before surgery. The corresponding incidences of methicillin-resistant staphylococci were 13%, 14%, 17%, and 5%, respectively. In adjusted group comparisons, the length of prior hospital stay was equally unrelated to future prophylaxis-resistant SSI (odds ratio 1.0, 95% confidence interval 0.99-1.01).

Conclusions

In our retrospective cohort of orthopedic implant SSI, the length of pre-surgical hospital stay was unrelated to the incidence of prophylaxis-resistant pathogens.

Classification, microbiology and treatment of diabetic foot infections

Diabetic foot ulcers (DFUs) are a common complication of type-1 and type-2 diabetes. About 10-15% of patients with diabetes develop foot ulcers. A validated foot ulcer classification system that will support the development of treatment strategis is necessary for clinicians managing DFUs. More than 10 classification systems have been described by researchers. Another important aspect of the management of DFUs is the proper identification of causative pathogens that trigger infections. While conventional diagnostic methods, such as swabs, cultures and biopsies are more widely used, novel molecular techniques have been exploring bacterial identification and quantification. Knowledge of the microbial aetiologies in diabetic foot infections, and understanding of antibiotic resistance, is critical for the effective management and treatment of these infected wounds. Initial antibiotic regimens are usually selected empirically. A set of common principles may help avoid selecting either an unnecessarily broad or inappropriately narrow antibiotic treatment regimen. In this review we provide a comprehensive summary and description of classification systems of diabetic foot infections, and a comprehensive discussion of microbiology.

Burden of Rifampicin- and Methicillin-Resistant Staphylococcus aureus in Italy

Rifampicin is one of the major drugs used on its own and also in combination to treat numerous infections sustained by methicillin-resistant Staphylococcus aureus (MRSA). In Italy, rifampicin resistance (RIF-R) is increasing in multidrug-resistant-MRSA isolates (16.4%), with respect to Europe (5.7%). In our study, the relationship between clones, rpoB mutations, and susceptibility profiles in 50 RIF-R MRSA isolated from hospitalized patients was evaluated. Antimicrobial susceptibility testing was performed by the broth microdilution method. Isolates were typed by MLST/SCCmec/spa-typing. The rpoB gene was analyzed by PCR and sequence analysis. RIF-R isolates were 60% heterogeneous vancomycin-intermediate S. aureus (hVISA) and 22% daptomycin nonsusceptible and belonged to the major MRSA clones: ST228-SCCmec I (44%), ST8-SCCmec IV (18%), ST239-SCCmec III (16%), ST5-SCCmec II (14%), and ST22-SCCmec IVh (4%). Thirteen diverse RpoB amino acid substitutions were identified. Half of the strains harbored the H481N substitution, conferring low-level resistance. Different single mutations at the equivalent locus (H481D; H481Y) or in other loci, and multiple mutations conferred high-level resistance. In conclusion, this study investigated the nature of RIF-R in Italy among RIF-R-MRSA strains, finding a prevalence of ST228, strongly associated with reduced susceptibility to glycopeptides (hVISA). The spread of RIF-R strains in clinical settings represents a serious threat, due to their complex resistance nature even to new anti-Gram-positive drugs, making these infections particularly difficult to treat.

Are antibiotic-resistant pathogens more common in subsequent episodes of diabetic foot infection?

BACKGROUND

After antibiotic therapy of an initial diabetic foot infection (DFI), pathogens isolated from subsequent episodes might become more resistant to commonly prescribed antibiotics. If so, this might require a modification of the current recommendations for the selection of empiric antibiotic therapy. This study investigated whether the Infectious Diseases Society of America (IDSA) DFI guideline recommendations should be modified based on the number of past DFI episodes.

METHODS

This was a single-centre retrospective cohort survey of DFI patients seen during the years 2010 to 2016.

RESULTS

A total 1018 episodes of DFI in 482 adult patients were identified. These patients were followed-up for a median of 3.3 years after the first DFI episode. The total number of episodes was 2257 and the median interval between recurrent episodes was 7.6 months. Among the recurrent DFIs, the causative pathogens were the same as in the previous episode in only 43% of cases (158/365). Staphylococcus aureus was the predominant pathogen in all episodes (range 1 to 13 episodes) and was not more prevalent with the increasing number of episodes. DFIs were treated with systemic antibiotics for a median duration of 20 days (interquartile range 11-35 days). Overall, there was no significant increase in the incidence of antibiotic resistance to methicillin, rifampicin, clindamycin, or ciprofloxacin over the episodes (Pearson's Chi-square test p-values of 0.76, 1.00, 0.06, and 0.46, respectively; corresponding p-values for trend of 0.21, 0.27, 0.38, and 0.08, respectively).

CONCLUSIONS

After the successful treatment of a DFI, recurrent episodes are frequent. A history of a previous DFI episode did not predict a greater likelihood of any antibiotic-resistant isolate in subsequent episodes. Thus, broadening the spectrum of empiric antibiotic therapy for recurrent episodes of DFI does not appear necessary.

Comparing the cost-effectiveness of linezolid to trimethoprim/sulfamethoxazole plus rifampicin for the treatment of methicillin-resistant Staphylococcus aureus infection: a healthcare system perspective

OBJECTIVE

Few industry-independent studies have been conducted to compare the relative costs and benefits of drugs to treat methicillin-resistant Staphylococcus aureus (MRSA) infection. We performed a stochastic cost-effectiveness analysis comparing two treatment strategies-linezolid versus trimethoprim-sulfamethoxazole plus rifampicin-for the treatment of MRSA infection.

METHODS

We used cost and effectiveness data from a previously conducted clinical trial, complementing with other data from published literature, to compare the two regimens from a healthcare system perspective. Effectiveness was expressed in terms of quality-adjusted life-years (QALYs). Several sensitivity analyses were performed using Monte Carlo simulation, to measure the effect of potential parameter changes on the base-case model results, including potential differences related to type of infection and drug toxicity.

RESULTS

Treatment of MRSA infection with trimethoprim-sulfamethoxazole plus rifampicin and linezolid were found to cost on average €146 and €2536, and lead to a gain of 0.916 and 0.881 QALYs, respectively. Treatment with trimethoprim-sulfamethoxazole plus rifampicin was found to be more cost-effective than linezolid in the base case and remained dominant over linezolid in most alternative scenarios, including different types of MRSA infection and potential disadvantages in terms of toxicity. With a willingness-to-pay threshold of €0, €50 000 and €200 000 per QALY gained, trimethoprim-sulfamethoxazole plus rifampicin was dominant in 100%, 96% and 85% of model iterations. A 95% discount on the current purchasing price of linezolid would be needed when it goes off-patent for it to represent better value for money compared with trimethoprim-sulfamethoxazole plus rifampicin.

CONCLUSIONS

Combined treatment of trimethoprim-sulfamethoxazole plus rifampicin is more cost-effective than linezolid in the treatment of MRSA infection.

Should daptomycin-rifampin combinations for MSSA/MRSA isolates be avoided because of antagonism?

PURPOSE

There is increasing clinical evidence from observational studies, that combination therapy of daptomycin with rifampin is a valuable treatment option for biofilm-associated difficult to treat Staphylococcus aureus infections such as osteomyelitis, prosthetic joint infection and endocarditis. However, two studies analyzing a limited number of S. aureus isolates reported an antagonism of those two drugs questioning the benefit of this combination.

METHODS

To estimate the frequency of this possible antagonism, we performed in vitro checkerboard assays on 58 consecutive clinical isolates of S. aureus (MSSA n = 9, MRSA n = 49). We determined the fractional inhibitory concentration index (FICI) and the susceptible breakpoint index (SBPI). All isolates were characterized by a microprobe array detecting 336 different genes/alleles to ensure their non-clonal origin.

RESULTS

For all isolates, the FICI was between 1.00 and 1.25 indicating additive effects for the daptomycin/rifampin combination. Neither antagonism nor synergism as defined by the FICI was found for any of the isolates.

CONCLUSION

Based on these data, there is no evidence to advise against the daptomycin/rifampin combination therapy.

Towards a definition of daptomycin optimal dose: Lessons learned from experimental and clinical data

Daptomycin exhibits excellent antibacterial activity against a wide range of Gram-positive bacteria. The on-label standard daily doses for daptomycin are 4 mg/kg for skin infections and 6 mg/kg for bacteraemia or right-sided endocarditis. Daptomycin bactericidal activity is predominantly concentration-dependent and by considering the values of pharmacokinetic targets established by several authors as well as the peak and trough concentrations of daptomycin obtained at various daily dosages, it appears that these targets can easily be reached with a dose of 6 mg/kg but only for a minimum inhibitory concentration (MIC) at 0.1 mg/L, and that for increasing MICs (e.g. 0.5 mg/L or 1 mg/L) these targets may only be attained with higher dosages (i.e. ≥10 mg/kg). High-dose (HD) daptomycin therapy has also been proven to be effective for reducing the risk of selection of daptomycin-resistant strains. Given the concentration-dependent bactericidal activity of daptomycin, the absence of a dose-toxicity relationship and the need to prevent the selection of resistant strains, we propose to consider for staphylococcal (i) skin and soft-tissue infections, daily doses of daptomycin of 6 mg/kg (new standard dose) and (ii) endocarditis or bacteraemia including those associated with intravascular catheter and implant-related infections, ≥10 mg/kg (HD) when the MIC is unknown or >0.25 mg/L, and 6-10 mg/kg (intermediate doses) when the MIC is ≤0.25 mg/L. For severe and deep-seated enterococcal infections, we propose high (≥10 mg/kg) daily doses of daptomycin in combination with another active agent, especially a β-lactam.

Daptomycin in combination with other antibiotics for the treatment of complicated methicillin-resistant Staphylococcus aureus bacteremia

PURPOSE

Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as one of the most important nosocomial pathogens. Resistance to antibiotic therapy has been known to emerge especially in clinically complex scenarios, resulting in challenges in determining optimal treatment of serious MRSA. Daptomycin, in combination with other antibiotics, has been successfully used in the treatment of these infections, with the aims of resulting in reducing the prevention of antimicrobial resistance and increased killing compared with daptomycin monotherapy.

METHODS

This article reviews all the published studies that used daptomycin combination therapy for the treatment of bacteremia and associated complicated infections caused by gram-positive organisms, including MRSA. We discuss the rationale of combination antibiotics and the mechanisms that enhance the activity of daptomycin, with special focus on the role of β-lactam antibiotics.

FINDINGS

There are limited clinical data on the use of daptomycin in combination with other antibiotics. Most of this use was as successful salvage therapy in the setting of failing primary, secondary, or tertiary therapy and/or relapsing infection. Synergy between β-lactams and daptomycin is associated with several characteristics, including increased daptomycin binding and β-lactam-mediated potentiation of innate immunity, but the precise molecular mechanism is unknown.

IMPLICATIONS

Use of daptomycin in combination with other antibiotics, especially β-lactams, offers a promising treatment option for complicated MRSA bacteremia in which emergence of resistance during treatment may be anticipated. Because it is currently not possible to differentiate complicated from uncomplicated bacteremia at the time of presentation, combination therapy may be considered as first-line therapy, with de-escalation to monotherapy in uncomplicated cases and cases with stable pharmacologic and surgical source control.

Do Diabetic Foot Infections With Methicillin-Resistant Staphylococcus aureus Differ From Those With Other Pathogens?

There is controversy as to whether or not diabetic foot infections (DFIs) caused by methicillin-resistant Staphylococcus aureus (MRSA) are associated with worse outcomes than DFIs caused by other pathogens. To address this issue we performed a nonsystematic literature search of published articles in English language journals seeking studies reporting on the outcomes of DFIs related to their microbiology. We retrieved 48 articles published from 1999 to 2013 that described a total of 7771 cases of DFI. The overall proportion of DFIs with an isolate of S aureus was about 30%; just over one third of these (11% of all cases) were MRSA strains. Among the DFI cases caused by MRSA 1543 were episodes of soft tissue infections and 113 of osteomyelitis, while non-MRSA organisms caused 5761 soft tissue infections and 354 cases of osteomyelitis. Only 5 of the included articles attempted a comparison between DFI caused by MRSA and those caused by other pathogens, with no clear differences noted. The median total duration of antibiotic therapy for DFI caused by MRSA was 26 days, of which a median of 10 days was given intravenously. Only a few articles reported the proportion of patients with a recurrence, but they often did not differentiate between MRSA and non-MRSA cases. Four publications reported a worse functional or microbiological outcome in MRSA, compared to non-MRSA, cases, but the findings were variable and differences did not seem to be significant. Many trials failed to adjust for case-mix or to definitively demonstrate a relationship between microbiology and outcomes. Few of the articles specifically commented on whether the MRSA isolates were health care- or community-acquired strains. Notwithstanding the substantial limitations of the available literature, there does not appear to be a need for any special treatment for DFI caused by MRSA. The current guidelines for treating according to established international recommendations seem appropriate.

In vivo interactions of continuous flucloxacillin infusion and high-dose oral rifampicin in the serum of 15 patients with bone and soft tissue infections due to Staphylococcus aureus - a methodological and pilot study

Background

Increased antibiotic resistance against Staphylococcus aureus and low penetration into bone requires regimen optimization of available drugs.

Methods

We evaluate pharmoacokinetic and pharmacodynamic parameters (PK/PD) as well as in vivo interactions of continuous flucloxacillin 12 g/d administration combined with high dose oral rifampicin 600 mg bid in the serum of 15 adult patients with bone and soft tissue infections. We use the patient’s own serum directed against his own isolated S. aureus strain to reproduce in vivo conditions as closely as possible.

Results

The continuous flucloxacillin infusion constantly generated plasma free drug levels largely exceeding the serum minimal inhibitory concentrations (mean 74-fold). Combination with rifampicin significantly increased flucloxacillin levels by 44.5%. Such an increase following rifampicin introduction was documented in 10/15 patients, whereas a decrease was observed in 1/15 patients. Finally, all infections were cured and the combination was well tolerated.

Conclusions

In this in vivo methodological pilot study among adult patients with orthopaedic infections due to S. aureus, we describe a new method and reveal substantial but inconsistent interactions between flucloxacillin and rifampicin, of which the clinical significance remains unclear.

Treatment options for methicillin-resistant Staphylococcus aureus (MRSA) infection: Where are we now?

Methicillin-resistant Staphylococcus aureus (MRSA) infection continues to be a substantial global problem with significant associated morbidity and mortality. This review summarises the discussions that took place at the 4th MRSA Consensus Conference in relation to the current treatment options for serious MRSA infections and how to optimise whichever therapy is embarked upon. It highlights the many challenges faced by both the laboratory and clinicians in the diagnosis and treatment of MRSA infections.