Effect of Vancomycin Therapy for Osteomyelitis on Colonization by Methicillin-ResistantStaphylococcus aureus: Lack of Emergence of Glycopeptide Resistance

In vitro drug release and antibacterial activity evaluation of silk fibroin coated vancomycin hydrochloride loaded poly (lactic-co-glycolic acid) (PLGA) sustained release microspheres

Currently, the treatment of osteomyelitis poses a great challenge to clinical orthopedics. The use of biodegradable materials combined with antibiotics provides a completely new option for the treatment of osteomyelitis. In this study, vancomycin hydrochloride (VANCO) loaded poly (lactic-co-glycolic acid) (PLGA) microspheres were prepared by a double emulsion solvent evaporation method, and the in vitro drug release behaviors of the drug loaded microspheres were explored after coating with different concentrations of silk fibroin (SF). Drug loading, encapsulation efficiency, Scanning electron microscopy, particle size analysis, Fourier transform infrared spectroscopy, hydrophilicity, in vitro drug release, and in vitro antibacterial activity were evaluated. The results showed that the drug loading of vancomycin loaded PLGA microspheres was (24.11 ±1.72)%, and the encapsulation efficiency was (48.21 ±3.44)%. The in vitro drug release indicated that the drug loaded microspheres showed an obvious initial burst release, and the drug loaded microspheres coated with SF could alleviate the initial burst release in varying degrees. It also can reduce the amount of cumulative drug release, and the effect of microspheres coated with 0.1% concentration of SF is the best. The time of in vitro drug release in different groups of drug loaded microspheres can be up to 28 days. The microspheres coated with (0.1%SF) or without (0%SF) SF showed a cumulative release of (82.50±3.51)% and (67.70±3.81)%,respectively. Therefore, the surface coating with SF of vancomycin loaded microspheres can alleviate the initial burst release, reduce the cumulative drug release, potentially prolong the drug action time, and improve the anti-infection effect.

Comparative analysis of beneficial effects of vancomycin treatment on Th1- and Th2-biased mice and the role of gut microbiota

AIMS

The aim was to understand the time-dependent antibiotic-induced perturbation pattern of gut microbiota and its effect on the innate immune and metabolic profile of the host.

METHODS AND RESULTS

Vancomycin was administered at 50 mg kg^-1 of body weight twice daily for six consecutive days to perturb the gut microbiota of C57BL/6 (Th1-biased) and BALB/c (Th2-biased) mice. Following treatment with vancomycin, we observed a reduction in the abundance of phyla Firmicutes and Bacteroides and an increase in Proteobacteria in the gut for both strains of mice following treatment with vancomycin till day 4. Abundance of Akkermansia muciniphila of Verrucomicrobia phylum also increased, from day 5 onwards following vancomycin treatment. The time-dependent variation of gut microbiota was associated with increased (i) expression of toll-like receptors and inflammatory genes such as TNF-α, IL-6, and IL-17, (ii) gut barrier permeability and (iii) blood glucose level of the host. The results also showed that (i) transplantation of cecal microbiota from vancomycin-treated day 6 mice to day 3 vancomycin-treated mice helped in restoring blood glucose level in C57BL/6 mice and (ii) short-chain fatty acids like acetate, butyrate and propionate changed with the alteration of gut microbiota to induce differential regulation of host immune response.

CONCLUSIONS

The current results revealed that an increase in A. muciniphila led to decreased inflammation and increased rate of glucose tolerance in the host. The treatment, with vancomycin till day 4, increased expression of inflammatory genes. The continuation of vancomycin for two more days reversed the effects. The effects were significantly more in C57BL/6 than BALB/c mice.

SIGNIFICANCE AND IMPACT OF THE STUDY

The current study established that the treatment with vancomycin till day 4 increased pathogenic bacteria but day 5 onwards provided significant health-related benefits to the host by increasing A. muciniphila more in C57BL/6 than BALB/c mice.

Clinical Utility of Methicillin-Resistant Staphylococcus aureus Nasal Screening for Antimicrobial Stewardship: A Review of Current Literature

Significant clinical and financial consequences are associated with both inadequate and unnecessary exposure to broad-spectrum antibiotics. As such, antimicrobial stewardship programs seek objective, reliable, and cost-effective tests to identify patients at highest or lowest risk for drug-resistant organisms to guide empirical antimicrobial selection. Use of methicillin-resistant Staphylococcus aureus (MRSA) nasal screening to rule out MRSA in lower respiratory tract infections has led to significant reductions in duration of vancomycin therapy. The clinical utility of MRSA nasal screening in other types of infection remains less clear. This review describes the performance of MRSA nasal screening in predicting MRSA infection, highlights practical considerations for use of MRSA nasal screening, and provides guidance for incorporating MRSA nasal screening into clinical practice. With a high negative predictive value when the prevalence of MRSA is low, MRSA nasal screening is a valuable antimicrobial stewardship tool with potential applications beyond lower respiratory tract infections. In appropriately selected patients, negative MRSA nasal screening can prevent initiation or guide discontinuation of anti-MRSA therapy. Antimicrobial stewardship programs should develop institutional guidelines to promote proper use of MRSA nasal screening. Pharmacists are well positioned to assist with education, interpretation, and application of MRSA nasal screening results.

Vancomycin: does it still have a role as an antistaphylococcal agent?

The recognition of the shortcomings of vancomycin as an antistaphylococcal agent, together with the burgeoning availability of alternative effective antistaphylococcal antibiotics, has led to a reassessment of the role of this glycopeptide antimicrobial in clinical therapeutics. Evidence indicates that vancomycin is inferior to semisynthetic penicillins in the treatment of infections due to methicillin-susceptible Staphylococcus aureus. Additional evidence suggests that vancomycin may be inferior to some comparator agents in the treatment of infections due to methicillin-resistant S. aureus (MRSA). While high-level resistance remains rare, data from some centers suggest an evolutionary change in S. aureus, evidenced by reduced susceptibility to vancomycin. This, together with the problem of heteroresistance to vancomycin, as well as poor tissue penetration after its systemic administration, presents potential obstacles to the successful therapy of S. aureus infections with this glycopeptide. While it has been suggested that these problems may be overcome by administration of vancomycin in much higher doses, the efficacy and safety of this approach remains to be determined and will require randomized clinical trials for its demonstration. A number of novel agents with activity against MRSA have been introduced to clinical practice in the last 2 years and others are still in the investigational stage. Despite the fact that these newer agents have been compared with vancomycin in trials only designed to demonstrate noninferiority, some potential evidence of superiority over vancomycin has emerged. While the relative roles of each of these newer agents and vancomycin can only be determined definitively by performance of adequately powered randomized clinical trials, current evidence suggests that vancomycin may be an inferior therapeutic agent.

[Antibiotic multiresistance in critical care units]

The presence of microorganisms with acquired resistance to multiple antibiotics complicates the management and outcome of critically ill patients. The intensivist, in his/her daily activity, is responsible for the prevention and control of the multiresistance and the challenge of prescribing the appropriate treatment in case of an infection by these microorganisms. We have reviewed the literature regarding the definition, important concepts related to transmission, recommendations on general measures of control in the units and treatment options. We also present data on the situation in our country known primarily through the ENVIN-UCI register. Addressing the multiresistance not only requires training but also teamwork with other specialists and adaptation to the local environment.

Liquid gentamicin and vancomycin in bone cement: a potentially more cost-effective regimen

This study investigated the use of liquid gentamicin, a much less costly antibiotic (<1/20 the price of tobramycin) with a broad antimicrobial spectrum, alone and in combination with vancomycin in bone cement. Standardized cement specimens loaded with 480 mg of liquid gentamicin, 4 g of powdered vancomycin, or both antibiotics were tested for elution characteristics, bioactivity, compressive strength, and porosity. Vancomycin elution was enhanced by 146% with the addition of gentamicin liquid, and gentamicin elution was enhanced by 45% when combined with vancomycin. Bioassay confirmed the bactericidal activity of the released antibiotics. Adding liquid gentamicin increased porosity, whereas adding vancomycin did not. Compressive strength decreased by 13%, 37%, and 45% in specimens containing vancomycin, liquid gentamicin, and both antibiotics, respectively. Despite inferior mechanical properties, the temporary nature of cement beads and spacers makes the liquid gentamicin-vancomycin mixture a potentially more cost-effective regimen in bone cement to treat musculoskeletal infections.

Counterpoint: Vancomycin and Staphylococcus aureus--an antibiotic enters obsolescence

The efficacy of vancomycin for the treatment of patients with infections due to Staphylococcus aureus is impaired by its poor tissue penetration and by its relatively weak antibacterial activity--an activity that is declining as S. aureus evolves. Neither dose escalation nor use of vancomycin in combination with other antibiotics that have antistaphylcoccal activity has been demonstrated to safely enhance its therapeutic efficacy. Although no clinical trials suggest superiority of vancomycin over any comparator, some have provided evidence of its inferiority. Strong consideration should be given to the use of alternative agents in the treatment of serious S. aureus infections.

High concentration and bioactivity of vancomycin and aztreonam eluted from Simplex cement spacers in two-stage revision of infected hip implants: a study of 46 patients at an average follow-up of 107 days

This study investigated the release of antibiotics in vivo, from an articulating polymethylmethacrylate (PMMA) spacer used in two-stage revision arthroplasty of infected hip implants. Forty-six patients who underwent two-stage revision hip arthroplasty for infections were managed with an interim PMMA spacer loaded with a high dose of vancomycin and aztreonam. Serum and aliquots of drainage collected after the first-stage surgery, and joint fluid obtained at the time of the second-stage surgery were analyzed for antibiotic concentrations by high performance liquid chromatography and bioactivity by tube dilution bioassay. Following implantation, the highest levels of antibiotics were measured in aliquots of drainage on the first day (vancomycin: 1538.0 +/- 243.6 microg/mL; aztreonam: 1003.5 +/- 323.5 microg/mL), decreasing to 571.9 +/- 169.4 microg/mL for vancomycin and 313.6 +/- 88.3 microg/mL for aztreonam after 7 days. Antibiotic concentrations in serum were very low (vancomycin: 0.58 +/- 0.2 microg/mL, range: 0.1-1.6 microg/mL; aztreonam: 0.46 +/- 0.3 microg/mL, range: 0.1-0.9 microg/mL at 24 h) and there was no systemic adverse effect. At a mean 107 days after the first-stage surgery, the concentrations of antibiotics in joint fluid were well above the minimal inhibitory concentration of most common microorganisms. The released antibiotics were bioactive against the test organisms. Based on the observed results, we confirmed the safety and effectiveness of in vivo drug delivery from antibiotic-impregnated PMMA hip spacers.

Guidelines for the prophylaxis and treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections in the UK

These evidence-based guidelines have been produced after a literature review of the treatment and prophylaxis of methicillin-resistant Staphylococcus aureus (MRSA) infection. The guidelines were further informed by antibiotic susceptibility data on MRSA from the UK. Recommendations are given for the treatment of common infections caused by MRSA, elimination of MRSA from carriage sites and prophylaxis of surgical site infection. There are several antibiotics currently available that are suitable for use in the management of this problem and potentially useful new agents are continuing to emerge.

A systematic approach to diabetic foot infections

Foot infection is the most common reason for hospitalization and subsequent lower extremity amputation among persons with diabetes. Foot ulceration caused by diabetic neuropathy, trauma, and peripheral vascular disease can lead to a limbor life-threatening infection. The optimum treatment of these potentially devastating conditions depends on a multidisciplinary approach that addresses the related or underlying disorders and thus ensures proper wound healing and a positive outcome. In addition to antibiotic therapy, severe soft-tissue or bone infections may necessitate surgical treatment, including drainage, débridement, and vascular reconstruction. Initial (empiric) antibiotic therapy should provide coverage against staphylococci and streptococci and should be revised according culture results. Antibiotic therapy is not indicated in clinically noninfected wounds. The duration of antibiotic treatment can range from 1 week for mild infections to 6 weeks or more for residual osteomyelitis and severe deep tissue infections. Aggressive (and sometimes repeated or staged) surgical intervention and appropriate antibiotic therapy can reduce the likelihood of a major amputation and the duration of hospitalization.

High dose vancomycin for osteomyelitis: continuous vs. intermittent infusion

OBJECTIVES

To compare the efficacy, ease of use and safety of intermittent vancomycin infusion (IVI) and continuous vancomycin infusion (CVI) in high-dose therapy of osteomyelitis.

METHODS

Forty-four patients with an osteomyelitis requiring vancomycin for more than 4 weeks were prospectively included, 21 receiving IVI and 23, CVI. The target serum concentration of vancomycin was 20-25 mg/L. Pharmacokinetics, adverse effects, and clinical efficacy were recorded.

RESULTS

The mean daily vancomycin dosing was the same in the two groups, but the serum vancomycin concentrations (trough or plateau) were lower in the IVI group than the CVI group (21.7 +/- 9.3 and 26.0 +/- 6.1 mg/L, respectively; P < 0.0001). The target concentrations were achieved quicker with CVI, and daily dosing was changed more frequently in the IVI group. After reaching the target, variability of vancomycin serum concentration (trough or plateau concentrations) was higher in the IVI group than in CVI group (standard deviation 7.9 mg/L vs. 5.6 mg/L, respectively; P = 0.001). CVI did not show clinical superiority, but adverse drug effects were more frequent in the IVI group as compared with the CVI group, 9 (42.9%) and 2 (8.7%), respectively (P = 0.03). Survival multiple regression using Cox's proportional hazard model showed that IVI (RR = 5.9, P = 0.03) and osteomyelitis of the foot (RR = 5.2, P = 0.01) were the only factors associated with adverse drug reactions leading to treatment termination.

CONCLUSIONS

CVI is practical and effective, and may be a good alternative for patients requiring prolonged treatment with high vancomycin serum levels.