Are Cephalosporins Adequate for Antimicrobial Prophylaxis for Cardiac Surgery Involving Implants?

Very early infective endocarditis after transcatheter aortic valve replacement

BACKGROUND

Scarce data exist about early infective endocarditis (IE) after trans-catheter aortic valve replacement (TAVR).

OBJECTIVE

The objective was to evaluate the characteristics, management, and outcomes of very early (VE) IE (≤ 30 days) after TAVR.

METHODS

This multicenter study included a total of 579 patients from the Infectious Endocarditis after TAVR International Registry who had the diagnosis of definite IE following TAVR.

RESULTS

Ninety-one patients (15.7%) had VE-IE. Factors associated with VE-IE (vs. delayed IE (D-IE)) were female gender (p = 0.047), the use of self-expanding valves (p < 0.001), stroke (p = 0.019), and sepsis (p < 0.001) after TAVR. Staphylococcus aureus was the main pathogen among VE-IE patients (35.2% vs. 22.7% in the D-IE group, p = 0.012), and 31.2% of Staphylococcus aureus infections in the VE-IE group were methicillin-resistant (vs. 14.3% in the D-IE group, p = 0.001). The second-most common germ was enterococci (34.1% vs. 24.4% in D-IE cases, p = 0.05). VE-IE was associated with very high in-hospital (44%) and 1-year (54%) mortality rates. Acute renal failure following TAVR (p = 0.001) and the presence of a non-enterococci pathogen (p < 0.001) were associated with an increased risk of death.

CONCLUSION

A significant proportion of IE episodes following TAVR occurs within a few weeks following the procedure and are associated with dismal outcomes. Some baseline and TAVR procedural factors were associated with VE-IE, and Staphylococcus aureus and enterococci were the main causative pathogens. These results may help to select the more appropriate antibiotic prophylaxis in TAVR procedures and guide the initial antibiotic therapy in those cases with a clinical suspicion of IE. Very early infective endocarditis after trans-catheter aortic valve replacement. VE-IE indicates very early infective endocarditis (≤30 days post TAVR). D-IE indicates delayed infective endocarditis.

Population Pharmacokinetic Model for Vancomycin Used in Open Heart Surgery: Model-Based Evaluation of Standard Dosing Regimens

The purpose of this study was to investigate the population pharmacokinetics of vancomycin in patients undergoing open heart surgery. In this observational pharmacokinetic study, multiple blood samples were drawn over a 48-h period of intravenous vancomycin in patients who were undergoing open heart surgery. Blood samples were analyzed using an Architect i4000SR immunoassay analyzer. Population pharmacokinetic models were developed using Monolix 4.4 software. Pharmacokinetic-pharmacodynamic (PK-PD) simulations were performed to explore the ability of different dosage regimens to achieve the pharmacodynamic targets. A total of 168 blood samples were analyzed from 28 patients. The pharmacokinetics of vancomycin are best described by a two-compartment model with between-subject variability in clearance (CL), the volume of distribution of the central compartment (V₁), and volume of distribution of the peripheral compartment (V₂). The CL and the V₁ of vancomycin were related to creatinine CL (CL_CR), body weight, and albumin concentration. Dosing simulations showed that standard dosing regimens of 1 and 1.5 g failed to achieve the PK-PD target of AUC_0-24/MIC > 400 for an MIC of 1 mg/liter, while high weight-based dosing regimens were able to achieve the PK-PD target. In summary, the administration of standard doses of 1 and 1.5 g of vancomycin two times daily provided inadequate antibiotic prophylaxis in patients undergoing open heart surgery. The same findings were obtained when 15- and 20-mg/kg doses of vancomycin were administered. Achieving the PK-PD target required higher doses (25 and 30 mg/kg) of vancomycin.

Prevention of surgical site infections

In the current era of pay-for-performance standards, the incidence of surgical site infections is increasingly becoming an institutional marker of quality assurance. Surgical site infections lead to increased morbidity and mortality in the surgical population and contribute to an already rising healthcare cost. As a result, the surgical community goes to great lengths to prevent this costly and occasionally lethal complication. Many practices are evidence based, however, many are not. In this article, the most commonly used preventive strategies in practice today and the evidence behind each are reviewed. In addition, an overview of the epidemiology, pathophysiology and microbiology of surgical site infections will be provided.

Interrupted time series analysis of vancomycin compared to cefuroxime for surgical prophylaxis in patients undergoing cardiac surgery

The increased incidence of methicillin-resistant Staphylococcus aureus (MRSA), the emergence of community-acquired MRSA, and the continued high incidence of methicillin-resistant Staphylococcus epidermidis have required that certain institutions choose vancomycin for surgical prophylaxis. However, the data supporting the use of vancomycin for surgical prophylaxis are controversial. The purpose of this project was to assess the effect of the change from cefuroxime to vancomycin for surgical site infection (SSI) rates in patients undergoing coronary artery bypass graft (CABG) surgery. The monthly rates of SSIs from 2001 to 2005 were analyzed before and after a change from cefuroxime to vancomycin antibiotic prophylaxis in patients undergoing CABG by using an interrupted time series analysis. Patients who underwent cardiac valve replacement surgery and who had received vancomycin during the entire study period were used as a comparator group. A total of 6,465 patients underwent CABG surgery (n = 4,239) or valve replacement surgery (n = 2,226) during the study period. On average, the monthly SSI incidence rate in patients undergoing CABG surgery decreased by 2.1 cases per 100 surgeries after the switch from cefuroxime to vancomycin (P = 0.042) when patients undergoing valve replacement were used as a comparator group. The change in SSI rates was associated with a decrease in the incidence of infections caused by coagulase-negative Staphylococcus and MRSA isolates, with little change in the incidence of SSIs due to other gram-positive organisms or gram-negative organisms. In institutions with a high incidence of methicillin-resistant Staphylococcus species, this study provides evidence for the clinical efficacy of vancomycin prophylaxis for the prevention of postoperative SSIs in patients undergoing CABG surgery.

Vascular Graft Infection by Staphylococcus aureus: Efficacy of Cefazolin, Teicoplanin and Vancomycin Prophylaxis Protocols in a Rat Model

OBJECTIVES

Prophylactic efficiencies of cefazolin, teicoplanin and vancomycin in a dacron graft infection model caused by methicillin-susceptible (MSSA) or -resistant Staphylococcus aureus (MRSA) were investigated.

DESIGN

Prospective, randomized, controlled animal study.

MATERIALS AND METHODS

Infections were established subcutaneously in the back of rats by implantation of Dacron prostheses followed by topical inoculation onto grafts of MSSA or MRSA. Experimental groups were as follows: Uncontaminated group (control), MSSA- or MRSA-contaminated and untreated groups, MSSA- or MRSA-contaminated groups treated with cefazolin, teicoplanin or vancomycin by one of three regimens (one day, two days, or three days regimen). Grafts were removed 7 days after the implantation and evaluated by using sonication and quantitative blood agar culture.

RESULTS

Contaminated groups demonstrated graft infections. Cefazolin, teicoplanin and vancomycin profoundly prevented the graft infections in MSSA- or MRSA-contaminated groups. For each antibiotic regimen, the most effective prevention was achieved by the drugs given as three days regimen. For MSSA and MRSA, the order of the effectiveness was as follows: teicoplanin>vancomycin>cefazolin.

CONCLUSION

As a prophylactic agent, teicoplanin seems to be more effective than vancomycin and cefazolin against vascular graft infections caused by MSSA and MRSA in rats.

The Surgical Infection Prevention and Surgical Care Improvement Projects: Promises and Pitfalls

Variations in outcomes for patients who have surgery are well known, and there is extensive evidence that failure to apply standards of care known to prevent adverse events results in patient harm. Infections and postoperative sepsis, cardiovascular complications, respiratory complications, and thromboembolic complications represent some of the most common adverse events that occur after surgery. Patients who experience postoperative complications have increased hospital length of stay, readmission rates, and mortality rates; in addition, costs of care are increased for patients, hospitals, and payers. In 2002, the Centers for Medicare and Medicaid Services, in collaboration with the Centers for Disease Control and Prevention, implemented the Surgical Infection Prevention Project to decrease the morbidity and mortality associated with postoperative surgical site infections. More recently, the Surgical Care Improvement Project, a national quality partnership of organizations committed to improving the safety of surgical care has been implemented. Although the Surgical Care Project does not focus on the complete set of important surgical quality issues, it does provide the incentive and infrastructure for national data collection and quality improvement activities for hospitals. There is now a strong national commitment to measure processes and outcomes of care for surgery in the United States.

The surgical infection prevention and surgical care improvement projects: national initiatives to improve outcomes for patients having surgery

Among the most common complications that occur after surgery are surgical site infections and postoperative sepsis, cardiovascular complications, respiratory complications (including postoperative pneumonia), and thromboembolic complications. Patients who experience postoperative complications have dramatically increased hospital length of stay, hospital costs, and mortality rates. The Centers for Medicare & Medicaid Services, in collaboration with the Centers for Disease Control and Prevention, has implemented the Surgical Infection Prevention Project to decrease the morbidity and mortality associated with postoperative surgical site infections. More recently, the Surgical Care Improvement Project, a national quality partnership of organizations committed to improving the safety of surgical care, has been announced. This review will provide an update from the Surgical Infection Prevention Project and provide an introduction to the Surgical Care Improvement Project.

Pharmacokinetic–pharmacodynamic aspects of antimicrobial prophylaxis with teicoplanin in patients undergoing major vascular surgery

A prospective, two-arm, open study assessing plasma exposure to teicoplanin with two different prophylactic regimens (Group A (n = 23), 800 mg pre-operatively versus Group B (n = 24), 400 mg pre-operatively plus two doses of 200 mg 24 h apart) was carried out in patients undergoing major vascular surgery. The intent was to define the feasibility and the possible advantages of the single pre-operative high dose in ensuring therapeutically effective plasma concentrations (>10 mg/L) of teicoplanin even during long-lasting operations. At the end of the intervention, mean teicoplanin concentrations (+/-S.D.) were 14.05 +/- 5.13 mg/L and 5.39 +/- 2.13 mg/L in Groups A and B, respectively. At 24 h, average teicoplanin levels were 5.10 +/- 1.25 mg/L and 2.08 +/- 0.73 mg/L in Groups A and B, respectively; at 48 h they declined to 2.86 +/- 0.70 mg/L in Group A, whereas they rose to 2.67 +/- 0.82 mg/L after administration of 2.63 +/- 0.51 mg/kg at 24 h in Group B. Single pre-operative high-dose teicoplanin may ensure effective plasma levels even in cases of very long-lasting operations (>8 h) with no need for intraoperative re-dosing and may enable more appropriate prophylactic exposure than that achievable with the same total dose given in three administrations 24 h apart.