Antibiotic policies in surgery: a consensus paper

Morphomics-informed population pharmacokinetic and physiologically-based pharmacokinetic modeling to optimize cefazolin surgical prophylaxis

INTRODUCTION

Cefazolin is the leading antibiotic used to prevent surgical site infections worldwide. Consensus guidelines recommend adjustment of the cefazolin dose above and below 120 kg without regard to body composition. Algorithms exist to repurpose radiologic data into body composition (morphomics) and inform dosing decisions in obesity.

OBJECTIVES

To compare the current standard of body weight to morphomic measurements as covariates of cefazolin pharmacokinetics and aid dose stratification of cefazolin in patients with obesity undergoing colorectal surgery.

METHODS

This prospective study measured cefazolin plasma, fat, and colon tissue concentrations in colorectal surgery patients in order to develop a morphomics-informed population pharmacokinetic (PopPK) model to guide dose adjustments. A physiologically-based pharmacokinetic (PBPK) model was also constructed to inform tissue partitioning in morbidly obese patients (n = 21, body mass index ≥35 kg/m2 with one or more co-morbid conditions).

RESULTS

Morphomics and pharmacokinetic data were available in 58 patients with a median [min, max] weight and age of 95.9 [68.5, 148.8] kg and 55 [25, 79] years, respectively. The plasma-to-subcutaneous fat partition coefficient was predicted to be 0.072 and 0.060 by the PopPK and PBPK models, respectively. The estimated creatinine clearance (eCLcr ) and body depth at the third lumbar vertebra (body depth_L3) were identified as covariates of cefazolin exposure. The probability of maintaining subcutaneous fat concentrations above 2 μg/mL for 100% of a 4-h surgical period was below 90% when eCLcr ≥105 mL/min and body depth_L3 ≥ 300 mm and less sensitive to the rate of infusion between 5 and 60 min.

CONCLUSIONS

Kidney function and morphomics were more informative than body weight as covariates of cefazolin target site exposure. Data from more diverse populations, consensus on target cefazolin exposure, and comparative studies are needed before a change in practice can be implemented.

Current Antimicrobial Use in Horses Undergoing Exploratory Celiotomy: A Survey of Board-Certified Equine Specialists

In the past decade, there has been a considerable increase in the recognition of antimicrobial resistance in equine practice. The objective of this study was to survey the current clinical use of antimicrobials for a commonly performed surgical procedure (exploratory celiotomy) with the goal of understanding how recent literature and changes in microbial resistance patterns may have impacted antimicrobial selection practices. An electronic survey was distributed to veterinary professionals within the American College of Veterinary Internal Medicine (ACVIM) and the American College of Veterinary Surgery (ACVS). A total of 113 completed surveys were returned. Practitioners reported antimicrobials were most frequently given 30-60 min preoperatively (63.1%). Two antimicrobial classes were typically administered (95.5%), with gentamicin (98.2%) and potassium penicillin (74.3%) being the most common. Antimicrobials were typically not re-dosed intraoperatively (78.6%). Factors that affected overall treatment length postoperatively included resection (81.4%), bloodwork (75.2%), enterotomy (74.3%), fever (85.0%), incisional complications (76.1%), and thrombophlebitis (67.3%). The most common duration of antimicrobial use was 1-3 d for non-strangulating lesions (54.4% of cases) and inflammatory conditions such as enteritis or peritonitis (50.4%), and 3-5 d for strangulating lesions (63.7%). Peri-incisional and intra-abdominal antimicrobials were used by 24.8% and 11.5% of respondents, respectively. In summary, antimicrobial usage patterns were highly variable among practitioners and, at times, not concordant with current literature.

Prevalence of antibiotic use in a tertiary care hospital in Italy, 2008-2016

BACKGROUND

Few data are available about temporal trends of antibiotic use in hospitalized children. The aim of the current study was to investigate the pattern and trends of antibiotic use over the years 2008-2016 in the largest children's hospital in Italy.

METHODS

Annual point prevalence surveys of antibiotic use were conducted by reviewing medical charts of 0-17 year-old children hospitalized for ≥48 h. Prevalence of antibiotic use was computed by year, type of ward and indication. Trends in prevalence over time were evaluated using the Cochrane-Armitage test. Possibile determinants of antibiotic use were assessed at univariate analysis and through a logistic regression model.

RESULTS

Out of 3015 children, 1516 (50.3%) received antibiotics, 58.1% of which for medical/surgical prophylaxis. Prevalence of antibiotic use increased from 42.0% in 2008 to 56.2% in 2016 (p = 0.001). The prevalence of patients receiving antibiotics for medical prophylaxis increased from 6.1% in 2008 to 24.2% in 2016 (p < 0.001), whereas the prevalence of patients receiving antibiotics for surgical prophylaxis significantly decreased (from 13.7 to 11.8%; p = 0.04); no significant temporal trends were found in antibiotic use for treating infections. The administration of third-generation cephalosporins for surgical and medical prophylaxis significantly decreased over time, while the proportion of antibiotics prescribed to treat infections after microbiological investigations significantly increased. Year (ORadj: 1.8 in 2016 compared to 2008, p < 0.001), age (ORadj ≥1.5 in children ≥1 year, compared to infants ≤2 months, p < 0.001), length of stay (LOS) (ORadj: 1.4 in case of LOS between 8 and 30 days compared to LOS ≤ 7 days, p < 0.001), and type of ward (ORadj: ≥1.3 in intensive-care, surgical and medical-subspecialty units compared to medical units, p < 0.001) were significantly and independently associated with antibiotic use.

CONCLUSIONS

Comparing prevalence rates of antibiotic use among hospitals and over time should consider differences in patient characteristics, such as age, ward of hospitalization and length of stay. Over the years, we documented an improvement in the choice of antibiotics prescribed for medical and surgical prophylaxis. However, further efforts are needed to avoid antibiotic misuse for medical prophylaxis, and to reduce the empirical use of broad spectrum antibiotics.

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.

Prior inpatient admission increases the risk of post-operative infection in hepatobiliary and pancreatic surgery

BACKGROUND

Hepatobiliary and pancreatic (HPB) operations have a high incidence of post-operative nosocomial infections. The aim of the present study was to determine whether hospitalization up to 1 year before HPB surgery is associated with an increased risk of post-operative infection, surgical-site infection (SSI) and infection resistant to surgical chemoprophylaxis.

METHODS

A retrospective cohort study of patients undergoing HPB surgeries between January 2008 and June 2013 was conducted. A multivariable logistic regression model was used for controlling for potential confounders to determine the association between pre-operative admission and post-operative infection.

RESULTS

Of the 1384 patients who met eligibility criteria, 127 (9.18%) experienced a post-operative infection. Pre-operative hospitalization was independently associated with an increased risk of a post-operative infection [adjusted odds ratio (aOR): 1.61, 95% confidence interval [CI]: 1.06-2.46] and SSI (aOR: 1.79, 95% CI: 1.07-2.97). Pre-operative hospitalization was also associated with an increased risk of post-operative infections resistant to standard pre-operative antibiotics (OR: 2.64, 95% CI: 1.06-6.59) and an increased risk of resistant SSIs (OR: 3.99, 95% CI: 1.25-12.73).

DISCUSSION

Pre-operative hospitalization is associated with an increased incidence of post-operative infections, often with organisms that are resistant to surgical chemoprophylaxis. Patients hospitalized up to 1 year before HPB surgery may benefit from extended spectrum chemoprophylaxis.

A pharmacokinetic/pharmacodynamic analysis of ceftaroline prophylaxis in patients with external ventricular drains

BACKGROUND

Ceftaroline is a broad-spectrum cephalosporin antibiotic with activity against drug-resistant bacteria, including strains of methicillin-resistant Staphylococcus aureus (MRSA), and may be useful to prevent and treat ventriculostomy-related infections (VRIs). The purpose of this study was to analyze the pharmacokinetics and pharmacodynamics of prophylactic ceftaroline in neurosurgical patients with an external ventricular drain (EVD).

METHODS

Adult patients in the neurosurgical intensive care unit with an EVD were given prolonged prophylaxis with ceftaroline. Serum and cerebral spinal fluid (CSF) were obtained simultaneously at 2, 6, and 12 h after initiation of the fourth dose of ceftaroline and concentrations were measured by a liquid chromatography tandem mass spectrometry assay. Time-kill curves against isolates of coagulase-negative S. aureus, methicillin-sensitive S. aureus, MRSA, and Streptococcus pneumoniae were determined in serum and CSF at each collection time point.

RESULTS

A total of five patients with a mean age of 63 y and mean weight of 83 kg were enrolled. The mean CSF:serum penetration ratios of ceftaroline were 0.005 (0.5%), 0.021 (2.1%), and 0.043 (4.3%) at 2, 6, and 12 h, respectively. The mean ceftaroline exposure ratio area under the curve (AUC)csf/AUCserum) was 0.011 (1.1%). Bactericidal activity at each collection time point was observed against each strain of staphylococci from serum samples and a penicillin-sensitive strain of S. pneumoniae from CSF samples.

CONCLUSION

This investigation suggests that ceftaroline could have clinical utility for the prevention of VRIs in patients with EVDs.

Antimicrobial use in horses undergoing colic surgery

BACKGROUND

Recommendations for antimicrobial prophylaxis for surgery are well-described in human medicine, but information is limited for veterinary practice.

OBJECTIVE

To characterize antimicrobial use in horses undergoing emergency colic surgery.

ANIMALS

A total of 761 horses undergoing emergency colic surgery (2001-2007).

METHODS

Retrospective case review. Antimicrobial dose and timing, surgical description, and duration of treatment were collected from medical records. Associations between antimicrobial use and the occurrence of fever, incisional inflammation or infection, catheter-associated complications, or Salmonella shedding during hospitalization were analyzed using rank-sum methods and logistic regression.

RESULTS

A total of 511 (67.2%) horses received an inappropriate amount of drug preoperatively. Median time from preoperative dose to incision was 70 (IQR 55-90) minutes; median total surgery time was 110 (IQR 80-160) minutes. Seventy-three horses were euthanized under anesthesia because of poor prognosis. Of 688 horses, 438 should have been redosed intraoperatively based on the duration of surgery. Only 8 (1.8%) horses were redosed correctly. Horses remained on perioperative antimicrobials a median of 3 (IQR 2-4.5) days. Antimicrobial therapy was reinstituted in 193 (28.9%) horses, and median days of total treatment were 3.8 (IQR 2-6). Signs that led to reinstituting therapy were fever (OR 3.13, P = .001) and incisional inflammation/infection (OR 2.95, P = .001). Horses in which treatment was reinstituted had 2.3 greater odds of shedding Salmonella (P = .003). Increased surgical time was associated with longer duration of antimicrobial therapy (OR 1.02, P = .001).

CONCLUSIONS AND CLINICAL RELEVANCE

Despite published recommendations regarding antimicrobial prophylaxis, compliance is poor; improvement might reduce postoperative complications.

Applying validated quality indicators to surgical antibiotic prophylaxis in a Brazilian hospital: learning what should be learned

BACKGROUND

Compliance with the best surgical antibiotic prophylaxis practice is usually low despite many published guidelines.

OBJECTIVE

This study investigated compliance with the Hospital Infection Control Committee guideline for antibiotic prophylaxis in a Brazilian hospital using quality indicators.

METHODS

A retrospective study was carried out from November 2009 to March 2010. Medical records from adult inpatients undergoing cardiac, neurologic, and orthopedic clean surgeries were included. The full compliance index was considered 100% when the antibiotic prophylaxis showed adequacy in all evaluated attributes. Analyses were conducted with 5% significance.

RESULTS

Medical records from 101 cardiac, 128 neurologic, and 519 orthopedic surgical patients were evaluated. The compliance index was 4.9%, and the compliance index according to specialty was 5.8%, 3.1%, and 3.0%, respectively, for orthopedic, neurologic, and cardiac surgeries. The attribute route of administration produced the best outcomes, whereas the attribute duration of antibiotic prophylaxis produced the worst. No association was identified between compliance to the attributes and patient characteristics.

CONCLUSION

This study showed a low level of adherence to Hospital Infection Control Committee guidelines for antibiotic prophylaxis. This suggests that different strategies should be implemented to promote the best possible practice in the field of antibiotic prophylaxis with greater surgeon engagement.

Rapid colonization with methicillin-resistant coagulase-negative staphylococci after surgery

BACKGROUND

Antimicrobial resistance may compromise the efficacy of antibiotic prophylaxis before surgery. The aim of this study was to measure susceptibility and clonal distribution of coagulase-negative staphylococci (CoNS) colonizing the skin around the surgery access site before and after the procedure.

METHODS

From March to September 2004, a series of 140 patients undergoing elective major abdominal surgery were screened for CoNS colonization at admission and 5 days after surgery. All isolates were tested for antibiotic susceptibility and genotyped by pulsed-field gel electrophoresis (PFGE).

RESULTS

Colonization rates with CoNS at admission and after surgery were 85% and 55%, respectively. The methicillin-resistant CoNS rate increased from 20% at admission to 47% after surgery (P = 0.001). The PFGE pattern after surgery revealed more patients colonized with identical clones: 8/140 patients (8/119 strains) and 26/140 patients (26/77 strains), respectively (P < 0.001).

CONCLUSIONS

Our results suggest rapid recolonization of disinfected skin by resistant nosocomial CoNS. Larger studies, preferably among orthopedic or cardiovascular patients, are required to clarify whether standard antibiotic prophylaxis with first- or second-generation cephalosporins for CoNS infections may be compromised if the patient requires an additional intervention 5 days or more after the initial surgery.

Non-compliance with recommendations for the practice of antibiotic prophylaxis and risk of surgical site infection: results of a multilevel analysis from the INCISO Surveillance Network

OBJECTIVES

The aim of this study was to determine which surgical antibiotic prophylaxis (SAP) practices alter surgical site infection (SSI) risk.

METHODS

Data were collected during a 7 year surveillance period (2001-07) from volunteer surgery wards participating in the INCISO Surveillance Network in Northern France. Main SAP practices, i.e. antibiotic choice, timing of first dose and total SAP duration, were evaluated and compliance checked based on French recommendations. The study focused on selected procedures in digestive, orthopaedic, gynaecological and cardiovascular surgery, for which standard SAP is recommended. Multilevel logistic regression analysis (a two-level random effect model) was carried out to identify SAP-, patient- and procedure-specific factors associated with SSI.

RESULTS

Of 8029 patients who underwent the selected surgeries, 91.3% received SAP and 2.5% developed SSI. Among those receiving SAP, 83.3% received appropriate antibiotic agents and 76.6% had an optimal timing of administration. SAP duration was considered to be appropriate in 35.0%, too long (SAP unnecessarily prolonged) in 45.2% and too short (lack of intra-operative redosing when recommended) in 19.8%. In the multivariate analysis, a too-short SAP duration remained the only inappropriate practice associated with higher SSI risk (odds ratio = 1.8, 95% confidence interval: 1.14-2.81), after adjustment for surgery procedure group, the National Nosocomial Infections Surveillance System risk index, age and infection risk variability among hospitals. No significant relationships were observed between SSI and the other SAP parameters.

CONCLUSIONS

A too-short SAP duration was the most important SAP malpractice associated with an increased risk of SSI. Information directed at practitioners should be reinforced based on standard recommendations.