Pharmacokinetics and Tissue Penetration of Cefoxitin in Obesity

Association Between Obesity and Wound Infection Following Colorectal Surgery: Systematic Review and Meta-Analysis

BACKGROUND

The aim of this meta-analysis is to comprehensively review and quantify the excess risk of surgical site infections (SSI) in obese patients following colorectal surgery.

METHODS

A systematic electronic search of the MEDLINE and EMBASE databases identified studies that investigated the association of obesity, defined by body mass index (BMI) with SSI among colorectal surgery patients.

RESULTS

Twelve studies were included in the final analysis. Patients with BMI ≥30 kg/m² were at 1.5 times (pooled OR 1.51, 95% CI: 1.39, 1.63, p < 0.001) higher odds of developing SSI after colorectal surgery when compared to BMI <30 kg/m². Subgroup analysis of the eight studies that investigated only elective procedures showed that the odds of developing SSI when BMI ≥30 kg/m² is 1.6 times that of those with BMI <30 kg/m² (pooled OR 1.60; 95% CI 1.34, 1.86; p < 0.001). The odds of having SSI when BMI is 25-29.9 kg/m² are 1.2 times than those with BMI <25 kg/m² (pooled OR 1.17; 95% CI 1.07, 1.28; p < 0.001).

CONCLUSION

Overweight and obese patients carry at least 20% and 50% higher odds of developing SSI after colorectal surgery compared to normal weight patients, respectively.

Prevention of Surgical Site Infections and Biofilms: Pharmacokinetics of Subcutaneous Cefazolin and Metronidazole in a Tumescent Lidocaine Solution

BACKGROUND

Tumescent anesthesia antibiotic delivery (TAAD) consists of subcutaneous infiltration of antibiotic(s) dissolved tumescent lidocaine anesthesia. Tumescent lidocaine anesthesia contains lidocaine (≤ 1 g/L), epinephrine (≤ 1 mg/L), sodium bicarbonate (10 mEq/L) in 0.9% saline. Our aim was to measure cefazolin and metronidazole concentrations over time in subcutaneous tumescent interstitial fluid (TISF) after TAAD, in serum after TAAD and after intravenous antibiotic delivery (IVAD). We hypothesize that the pharmacokinetic/pharmacodynamic profiles of TAAD + IVAD are superior to IVAD alone for the prevention of surgical site infections and biofilms.

METHODS

Concentrations of cefazolin and metronidazole in TISF and serum following TAAD and in serum following IVAD were compared in 5 female volunteers. Subjects received cefazolin or cefazolin plus metronidazole by IVAD alone and by TAAD alone. One subject also received concomitant IVAD and TAAD of these 2 antibiotics. Sequential samples of serum or subcutaneous TISF were assayed for antibiotic concentration.

RESULTS

Cefazolin (1 g) by TAAD resulted in an area under the curve of the concentration-time profile and a maximum concentration (Cmax) in subcutaneous tissue that were 16.5 and 5.6 times greater than in serum following 1 g by IVAD. Metronidazole (500 mg) by TAAD resulted in an area under the curve and Cmax that were 8.1 and 24.7 times greater in TISF, than in serum after 500 mg by intravenous delivery. IVAD + TAAD resulted in superior antibiotic concentrations to IVAD alone.

CONCLUSIONS

TAAD + IVAD produced superior antibiotic bioavailability in both subcutaneous interstitial fluid and serum compared with IVAD alone. There was no evidence that TAAD of cefazolin and metronidazole poses a significant risk of harm to patients.

The Surgical Infection Society Revised Guidelines on the Management of Intra-Abdominal Infection

BACKGROUND

Previous evidence-based guidelines on the management of intra-abdominal infection (IAI) were published by the Surgical Infection Society (SIS) in 1992, 2002, and 2010. At the time the most recent guideline was released, the plan was to update the guideline every five years to ensure the timeliness and appropriateness of the recommendations.

METHODS

Based on the previous guidelines, the task force outlined a number of topics related to the treatment of patients with IAI and then developed key questions on these various topics. All questions were approached using general and specific literature searches, focusing on articles and other information published since 2008. These publications and additional materials published before 2008 were reviewed by the task force as a whole or by individual subgroups as to relevance to individual questions. Recommendations were developed by a process of iterative consensus, with all task force members voting to accept or reject each recommendation. Grading was based on the GRADE (Grades of Recommendation Assessment, Development, and Evaluation) system; the quality of the evidence was graded as high, moderate, or weak, and the strength of the recommendation was graded as strong or weak. Review of the document was performed by members of the SIS who were not on the task force. After responses were made to all critiques, the document was approved as an official guideline of the SIS by the Executive Council.

RESULTS

This guideline summarizes the current recommendations developed by the task force on the treatment of patients who have IAI. Evidence-based recommendations have been made regarding risk assessment in individual patients; source control; the timing, selection, and duration of antimicrobial therapy; and suggested approaches to patients who fail initial therapy. Additional recommendations related to the treatment of pediatric patients with IAI have been included.

SUMMARY

The current recommendations of the SIS regarding the treatment of patients with IAI are provided in this guideline.

Quantitative Assessment of Visceral Obesity and Postoperative Colon Cancer Outcomes

BACKGROUND

Quantitative computed tomography (CT) assessment of visceral adiposity may be superior to body mass index (BMI) as a predictor of surgical morbidity. We sought to examine the association of CT measures of obesity and BMI with short-term postoperative outcomes in colon cancer patients.

METHODS

In this retrospective study, 110 patients treated with colectomy for stage I-III colon cancer were classified as obese or non-obese by preoperative CT-based measures of adiposity or BMI [obese: BMI ≥ 30 kg/m², visceral fat area (VFA) to subcutaneous fat area ratio (V/S) ≥0.4, and VFA > 100 cm²]. Postoperative morbidity and mortality rates were compared.

RESULTS

Obese patients, by V/S and VFA but not BMI, were more likely to be male and have preexisting hypertension and diabetes. The overall complication rate was 25.5%, and there were no mortalities. Obese patients by VFA (with a trend for V/S but not BMI) were more likely to develop postoperative complications as compared to patients classified as non-obese: VFA (30.5 vs.10.7%, p = 0.03), V/S (29.2 vs. 9.5%, p = 0.05), and BMI (32.4 vs. 21.9%, p = 0.23).

CONCLUSIONS

Elevated visceral obesity quantified by CT is associated with the presence of key metabolic comorbidities and increased postoperative morbidity and may be superior to BMI for risk stratification.

Pharmacokinetic and Pharmacodynamic Evaluation of a Weight-Based Dosing Regimen of Cefoxitin for Perioperative Surgical Prophylaxis in Obese and Morbidly Obese Patients

The objective of this study was to determine the pharmacokinetics and pharmacodynamics (PK/PD) of a weight-based cefoxitin dosing regimen for surgical prophylaxis in obese patients. Patients received a single dose of cefoxitin at 40 mg/kg based on total body weight. Cefoxitin samples were obtained over 3 h from serum and adipose tissue, and concentrations were determined by validated high-performance liquid chromatography. Noncompartmental pharmacokinetic analysis was performed, followed by Monte Carlo simulations to estimate probability of target attainment (PTA) for Staphylococcus aureus, Escherichia coli, and Bacteroides fragilis over 4-h periods postdose. Thirty patients undergoing bariatric procedures were enrolled. The body mass index (mean ± standard deviation [SD])was 45.9 ± 8.0 kg/m(2) (range, 35.0 to 76.7 kg/m(2)); the median cefoxitin dose was 5 g (range, 4.0 to 7.5 g). The mean maximum concentrations were 216.15 ± 41.80 μg/ml in serum and 12.62 ± 5.89 in tissue; the mean tissue/serum ratio was 8% ± 3%. In serum, weight-based regimens achieved ≥90% PTA (goal time during which free [unbound] drug concentrations exceed pathogen MICs [fT>MIC] of 100%) for E. coli and S. aureus over 2 h and for B. fragilis over 1 h; in tissue this regimen failed to achieve goal PTA at any time point. The 40-mg/kg regimens achieved higher PTAs over longer periods in both serum and tissue than did the standard 2-g doses. However, although weight-based cefoxitin regimens were better than fixed doses, achievement of desired pharmacodynamic targets was suboptimal in both serum and tissue. Alternative dosing regimens and agents should be explored in order to achieve more favorable antibiotic performance during surgical prophylaxis in obese patients.

Risk Factors for Surgical Site Infections Following Adult Spine Operations

OBJECTIVE

To identify risk factors for surgical site infections (SSIs) after spine operations.

DESIGN

Case-control study of SSIs among patients undergoing spine operations.

SETTING

An academic health center.

PATIENTS

We studied patients undergoing spinal fusions or laminectomies at the University of Iowa Hospitals and Clinics from January 1, 2007, through June 30, 2009. We included patients who acquired SSIs meeting the National Healthcare Safety Network definition. We randomly selected controls among patients who had spine operations during the study period and did not meet the SSI definition.

RESULTS

In total, 54 patients acquired SSIs after 2,309 spine operations (2.3 per 100 procedures). SSIs were identified a median of 20 days after spinal fusions and 17 days after laminectomies; 90.7% were identified after discharge and 72.2% were deep incisional or organ-space infections. Staphylococcus aureus caused 53.7% of SSIs. Of patients with SSIs, 64.9% (fusion) and 70.6% (laminectomy) were readmitted and 59.5% (fusion) and 64.7% (laminectomy) underwent reoperation. By multivariable analysis, increased body mass index, Surgical Department A, fusion of 4–8 vertebrae, and operation at a thoracic or lumbar/sacral level were significant risk factors for SSIs after spinal fusions. Lack of private insurance and hypertension were significant risk factors for SSIs after laminectomies. Surgeons from Department A were more likely to use nafcillin or vancomycin for perioperative prophylaxis and to do more multilevel fusions than surgeons from Department B.

CONCLUSIONS

SSIs after spine operations significantly increase utilization of healthcare resources. Possible remediable risk factors include obesity, hypertension, and perioperative antimicrobial prophylaxis.

Infect Control Hosp Epidemiol 2016;1458–1467

Patient-Related Risk Factors for Periprosthetic Joint Infection after Total Joint Arthroplasty: A Systematic Review and Meta-Analysis

BACKGROUND

Periprosthetic joint infections (PJIs) are dreaded complications of total joint arthroplasties. The risk of developing PJIs is likely to be influenced by several patient factors such as sociodemographic characteristics, body mass index (BMI), and medical and surgical histories. However, the nature and magnitude of the long-term longitudinal associations between these patient-related factors and risk of developing PJIs are uncertain.

OBJECTIVE

To conduct a systematic review and meta-analysis to assess the associations between several patient-related factors and PJI.

DATA SOURCES

MEDLINE, EMBASE, Web of Science, Cochrane Library, and reference lists of relevant studies from inception to September 2015.

STUDY SELECTION

Longitudinal studies with at least one-year of follow-up for PJIs after total joint arthroplasty.

DATA EXTRACTION AND SYNTHESIS

Two investigators extracted data on study characteristics, methods, and outcomes. A consensus was reached with involvement of a third. The relative risk (RR) with 95% confidence intervals was used as the summary measure of association across studies. Study-specific RRs with 95% confidence intervals were meta-analysed using random effect models and were grouped by study-level characteristics.

RESULTS

Sixty-six observational (23 prospective cohort and 43 retrospective cohort or case-control) studies with data on 512,508 participants were included. Comparing males to females and smokers to non-smokers, the pooled RRs for PJI were 1.36 (1.18-1.57) and 1.83 (1.24-2.70) respectively. There was no evidence of any significant associations of PJI with age and high alcohol intake. Comparing BMI ≥ 30 versus < 30 kg/m(2); ≥ 35 versus < 35 kg/m(2); and ≥ 40 versus < 40 kg/m(2); the pooled RRs were 1.60 (1.29-1.99); 1.53 (1.22-1.92); and 3.68 (2.25-6.01) respectively. Histories of diabetes, rheumatoid arthritis, depression, steroid use, and previous joint surgery were also associated with increased risk of PJI. The results remained similar when grouped by relevant study level characteristics.

CONCLUSIONS

Several potentially modifiable patient-related factors are associated with the risk of developing PJIs. Identifying patients with these risk factors who are due to have arthroplasty surgery and modulating these risk factors might be essential in reducing the incidence of PJI. Further research is however warranted to assess the potential clinical utility of these risk factors as risk assessment tools for PJI.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO 2015: CRD42015023485.

Periprosthetic joint infection

Periprosthetic joint infections are a devastating complication after arthroplasty and are associated with substantial patient morbidity. More than 25% of revisions are attributed to these infections, which are expected to increase. The increased prevalence of obesity, diabetes, and other comorbidities are some of the reasons for this increase. Recognition of the challenge of surgical site infections in general, and periprosthetic joint infections particularly, has prompted implementation of enhanced prevention measures preoperatively (glycaemic control, skin decontamination, decolonisation, etc), intraoperatively (ultraclean operative environment, blood conservation, etc), and postoperatively (refined anticoagulation, improved wound dressings, etc). Additionally, indications for surgical management have been refined. In this Review, we assess risk factors, preventive measures, diagnoses, clinical features, and treatment options for prosthetic joint infection. An international consensus meeting about such infections identified the best practices and further research needs. Orthopaedics could benefit from enhanced preventive, diagnostic, and treatment methods.

Cefoxitin Plasma and Subcutaneous Adipose Tissue Concentration in Patients Undergoing Sleeve Gastrectomy

PURPOSE

Antibiotic dosing in obese surgical patients has not been adequately evaluated. The objective of this study was to identify whether currently prescribed doses of cefoxitin achieve adequate and sustained plasma and tissue concentrations in obese patients undergoing sleeve gastrectomy.

METHODS

A prospective evaluation of plasma and tissue cefoxitin concentrations in patients undergoing sleeve gastrectomy was performed. On the day of the surgical procedure, venous blood samples (5 mL) were collected just before cefoxitin administration and then at 5, 30, 60, 120, and 240 minutes after dose administration. In addition, subcutaneous adipose tissue was collected from the surgical site at the time of surgical incision and at closure. Cefoxitin concentrations in the collected samples were quantified by using an HPLC-ultraviolet method. A standard noncompartmental analysis was performed for each individual cefoxitin plasma concentration-time profile. In addition, the ratio of tissue to plasma concentration was calculated for all patients.

FINDINGS

Plasma and tissue pharmacokinetics of cefoxitin were evaluated in 6 patients undergoing sleeve gastrectomy. The mean age and BMI were 48.7 (6.2) years and 42.8 (7.1) kg/m(2), respectively. At the time of surgical closure, subcutaneous adipose tissue concentrations of cefoxitin were subtherapeutic (<8 µg/mL) in all evaluated patients.

IMPLICATIONS

Current dosing strategies for cefoxitin in obese surgical patients may be inadequate, and there is an urgent need to define the appropriate dosage.

Interaction of obesity and infections

There is evidence that certain infections may induce obesity. Obese persons may also have more severe infections and have compromised response to therapies. The objective of this study is to review the available literature identifying infections that potentially contribute to greater body mass index (BMI) and differential responses of overweight and obese persons to infections. A systematic literature review of human studies examining associations between infections and weight gain, differential susceptibility, severity, and response to prevention and treatment of infection according to BMI status (January 1980-July 2014) was conducted. Three hundred and forty-three studies were eligible for inclusion. Evidence indicated that viral infection by human adenovirus Ad36 and antibiotic eradication of Helicobacter pylori were followed by weight gain. People who were overweight or obese had higher susceptibility to developing post-surgical infections, H1N1 influenza and periodontal disease. More severe infections tended to be present in people with a larger BMI. People with a higher BMI had a reduced response to vaccinations and antimicrobial drugs. Higher doses of antibiotics were more effective in obese patients. Infections may influence BMI, and BMI status may influence response to certain infections, as well as to preventive and treatment measures. These observations have potential clinical implications.

Pharmacokinetics of cefazolin prophylaxis in obese gravidae at time of cesarean delivery

OBJECTIVE

The objective of the study was to compare the pharmacokinetics of 2 g and 3 g doses of cefazolin when used for perioperative prophylaxis in obese gravidae undergoing cesarean delivery.

STUDY DESIGN

We performed a double-blinded, randomized controlled trial from August 2013 to April 2014. Twenty-six obese women were randomized to receive either 2 or 3 g intravenous cefazolin within 30 minutes of a skin incision. Serial maternal plasma samples were obtained at specific time points up to 8 hours after drug administration. Umbilical cord blood was obtained after placental delivery. Maternal adipose samples were obtained prior to fascial entry, after closure of the hysterotomy, and subsequent to fascial closure. Pharmacokinetic parameters were determined via noncompartmental analysis.

RESULTS

The median area under the plasma concentration vs time curve was significantly greater in the 3 g group than in the 2 g group (27204 μg/mL per minute vs 14058 μg/mL per minute; P = .001). Maternal plasma concentrations had an impact by body mass index. For every 1 kg/m(2) increase in body mass index at the time of the cesarean delivery, there was an associated 13.77 μg/mL lower plasma concentration of cefazolin across all time points (P = .01). By the completion of cesarean delivery, cefazolin concentrations in maternal adipose were consistently above the minimal inhibitory concentration for both Gram-positive and Gram-negative bacteria with both the 2 g and 3 g doses. The median umbilical cord blood concentrations were significantly higher in the 3 g vs the 2 g group (34.5 μg/mL and 21.4 μg/mL; P = .003).

CONCLUSION

Cefazolin concentrations in maternal adipose both at time of hysterotomy closure and fascial closure were above the minimal inhibitory concentration for both Gram-positive and Gram-negative bacteria when either 2 g or 3 g cefazolin was administered as perioperative surgical prophylaxis. Maternal cefazolin concentrations in plasma and maternal adipose tissue are related to both dose and body mass index.

Impact of obesity on the risk of wound infection following surgery: results from a nationwide prospective multicentre cohort study in England

We sought to assess the impact of body mass index on the risk of surgical site infection in a prospective cohort study of 206 National Health Service (NHS) hospitals in England between 2007 and 2011. Body mass index was available for 159,720 of 350,089 operations among patients undergoing abdominal hysterectomy, coronary artery bypass graft, hip replacement, knee replacement, or large-bowel surgery. Among these patients, the risk of surgical site infection ranged from 0.65% for knee replacement to 11.04% for large-bowel surgery. Overall, 127,512 (79.8%) patients were overweight or obese (body mass index of ≥25 kg/m(2)). Obesity was associated with a 1.1-fold to 4.4-fold increase in the adjusted odds of developing surgical site infection as compared with normal weight, depending on the type of surgery. The population-attributable fraction (PAF) for body mass index was greatest in overweight (body mass index of 25.0-29.9 kg/m(2)) patients undergoing coronary artery bypass graft, accounting for 15% of their overall risk of surgical site infection (PAF 0.15; 95% CI 0.09-0.22). Being overweight or obese substantially increased the likelihood of patients developing surgical site infection. Given the increasingly high proportion of the surgical population who are overweight, this is likely to place a considerable additional burden on the NHS. Strategies for mitigating this excess risk need to be found.

The enhanced healing of a high-risk, clean, sutured surgical incision by prophylactic negative pressure wound therapy as delivered by Prevena™ Customizable™: cosmetic and therapeutic results

According to the literature, incisional closure complications may range from postoperative surgical site infections, representing 17-22% of health care-associated infections, surgical wound dehiscence and formation of haematomas or seromas, and can lead to delayed or impaired incision healing. These kinds of situations are more common when wounds are closed under tension or in specific patient morbidities. Obesity, in particular, is associated with an impaired blood flow to tissues, predisposing the patient to increased risk of wound complications by various mechanisms. Incisional complications can become relevant economic burdens for health care systems because of an increase in the average length of hospital stay and readmissions, and additional medical and surgical procedures. Thus, a preventive therapy may have a critical role in the management of healing. Negative pressure wound therapy (NPWT) technology as delivered by Prevena™ Customizable™ (Kinetic Concepts Inc., San Antonio, TX) has recently been the focus of a new investigation, as a prophylactic measure to prevent complications via immediate postoperative application in high-risk, clean, closed surgical incisions. The authors present a 62-year-old class II obese female, who underwent bilateral inguinal dermolipectomy. Prophylactic NPWT as delivered by Prevena™ was performed successfully over surgical incisions. Cosmetic and therapeutic results are shown.

What would surgeons like from materials scientists?

Surgery involves the repair, resection, replacement, or improvement of body parts and functions and in numerous ways, surgery should be considered human engineering. There are many areas in which surgical materials could be improved, but surgeons are generally unaware of materials available for use, while materials scientists do not know what surgeons require. This article will review some of the areas where surgeons and materials scientists have interacted in the past and will discuss some of the most pressing problems which remain to be solved. These include better implant materials for hernia repair, breast reconstruction, the treatment of diabetes, vascular stenting and reconstruction, and electrical pacing devices. The combination of tissue engineering and nanomaterials has great potential for application to nearly every aspect of surgery. Tissue engineering will allow cells or artificial organs to be grown for specific uses while nanotechnology will help to ensure maximal biocompatibility. Biosensors will be combined with improved electrodes and pacing devices to control impaired neurological functions.

[Infection prevention by the anesthesia team]

The anesthesia team acts every day in a highly complex and high risk environment for the transmission of pathogenic organisms and the induction of infectious complications. With strict adherence to standard precautions and infection control practices in particular regular hand disinfection before and after direct patient contact and before performance of aseptic tasks during anesthesia and an optimized perioperative process the members of the anesthesia team can become infection control pioneers within the hospital. In order to be successful, structural and organizational resources in the form of training, personnel, materials and time, need to be adequate for the situation. This review summarizes the infection control recommendations for anesthesia practice based on the most recent literature and guidelines and offers practical advice for commonly observed mistakes.

Infection following operations on the central nervous system: deconstructing the myth of the sterile field

Neurosurgical patients are at a high risk for infectious sequelae following operations. For neurosurgery in particular, the risk of surgical site infection has a unique implication given the proximity of the CSF and the CNS. Patient factors contribute to some degree; for example, cancer and trauma are often associated with impaired nutritional status, known risk factors for infection. Additionally, care-based factors for infection must also be considered, such as the length of surgery, the administration of steroids, and tissue devascularization (such as a craniotomy bone flap). When postoperative infection does occur, attention is commonly focused on potential lapses in surgical “sterility.” Evidence suggests that the surgical field is not free of microorganisms. The authors propose a paradigm shift in the nomenclature of the surgical field from “sterile” to “clean.” Continued efforts aimed at optimizing immune capacity and host defenses to combat potential infection are warranted.

Impact of obesity on surgical site infection in colon and rectal surgery

Obesity affects over 30% of the United States population. Over the past 10 years, there has been increased recognition of the prevalence of obesity and its contribution to worse outcomes among medical and surgical patients. In particular, obesity has been validated as a risk factor for surgical site infection (SSI) among patients undergoing major abdominal surgery with some reports demonstrating an increased risk of SSI as high as sixty percent (60%) among obese patients. For patients undergoing elective colon and rectal surgery, a higher incidence of SSI (up to 45%) has been reported in comparison to outcomes of other surgical procedures. Obesity, as well as numerous other variables, have been implicated as a potential source for this increased incidence. Although the pathophysiology of obesity-related SSI has been suggested (decreased wound oxygen tension, impaired tissue antibiotic penetration, altered immune function, etc.), the true effect of obesity has not been clearly described. The purpose of this review is to examine the growing epidemic of obesity and its specific impact on SSI for both general and colorectal surgical patients. The proposed mechanisms for why obesity increases the risk of SSI will be briefly discussed, as well.

Outcome of laparoscopic colorectal surgery in obese and nonobese patients: a meta-analysis

BACKGROUND

Obese patients are generally believed to be at increased risk for surgery compared with those who are not obese. A meta-analysis was performed to assess the outcomes of laparoscopic colorectal surgery in obese and nonobese patients.

METHODS

A systematic literature search from inception to June 2011 was performed. Pooled odds ratios (OR) and weighted mean differences (WMD) with 95% confidence intervals (95% CI) were calculated using the fixed effects model or random effects model.

RESULTS

Eight observational studies identified and matched the selection criteria. Conversion rates (OR: 2.31, 95% CI: 1.74-3.08), operating time (WMD: 15.33, 95% CI: 1.81-28.85), and postoperative morbidity (OR: 2.11; 95% CI: 1.3-3.42) were all significantly increased in the obese group. Length of hospital stay and mortality were similar in both groups. For patients with cancer, there was no difference between groups for the number of harvested nodes and length of specimen.

CONCLUSIONS

Obesity is associated with increased conversion rate, operating time, and postoperative morbidity of laparoscopic colorectal surgery but does not affect surgical safety or oncological security.