Effects of blood loss and fluid volume replacement on serum and tissue gentamicin concentrations during colorectal surgery

Prophylactic antibiotics for massive endoprostheses in orthopaedic oncology

The recently published Prophylactic Antibiotic Regimens In Tumor Surgery (PARITY) trial found no benefit in extending antibiotic prophylaxis from 24 hours to five days after endoprosthetic reconstruction for lower limb bone tumours. PARITY is the first randomized controlled trial in orthopaedic oncology and is a huge step forward in understanding antibiotic prophylaxis. However, significant gaps remain, including questions around antibiotic choice, particularly in the UK, where cephalosporins are avoided due to concerns of Clostridioides difficile infection. We present a review of the evidence for antibiotic choice, dosing, and timing, and a brief description of PARITY, its implication for practice, and the remaining gaps in our understanding.

Surgical site infection in pediatric spinal fusion surgery revisited: outcome and risk factors after preventive bundle implementation

Background

Surgical site infections (SSI) contribute to significant morbidity, mortality, length of stay, and financial burden. We sought to evaluate the incidence and risk factors of surgical site infection following pediatric spinal fusion surgery in patients for whom standard perioperative antibiotic prophylaxis and preventive strategies have been implemented.

Methods

We conducted a retrospective study of children aged <18 years who underwent spinal fusion surgery from January 2017 to November 2021 at a quaternary academic pediatric medical center. Univariable analysis was used to evaluate associations between potential risk factors and SSI.

Results

Of 1111 patients, 752 (67.6%) were female; median age was 14.2 years. SSI occurred in 14 patients (1.3%). Infections were superficial incisional (n=2; 14.3%), deep incisional (n=9; 64.3%), and organ/space (n=3; 21.4%). Median time to SSI was 14 days (range, 8 to 45 days). Staphylococcus aureus and Escherichia coli were the most frequently-isolated bacteria. Potential risk factors for SSIs included low body weight (Odds ratio (OR) 0.96, 95% confidence interval (CI) 0.93-0.99, p=0.026), ASA classification of ≥3 (OR 24.53, 95%CI 3.20-188.22, p=0.002), neuromuscular scoliosis (OR 3.83, 95%CI 3.82-78.32, p<0.001), prolonged operative time (OR 1.56, 95%CI 1.28-1.92, p<0.001), prolonged anesthetic time (OR 1.65, 95%CI 1.35-2.00, p<0.001), administration of prophylactic antibiotic ≥60 minutes before skin incision (OR 11.52, 95%CI 2.34-56.60, p=0.003), and use of povidone-iodine alone for skin preparation (OR 5.97, 95%CI 1.27-28.06, p=0.024).

Conclusion

In the context of a robust bundle for SSI prevention; low body weight, ASA classification of ≥3, neuromuscular scoliosis, prolonged operative and anesthetic times, administration of prophylactic antibiotic ≥60 minutes before skin incision, and use of povidone-iodine alone for skin preparation increased the risk of SSI. Administration of prophylactic antibiotic within 60 minutes of skin incision, strict adherence to high-risk preventive protocol, and use of CHG-alcohol could potentially reduce the rate of SSI.

National surgical antibiotic prophylaxis guideline in Singapore

Introduction: Institutional surgical antibiotic prophylaxis (SAP) guidelines are in place at all public hospitals in Singapore, but variations exist and adherence to guidelines is not tracked consistently. A national point prevalence survey carried out in 2020 showed that about 60% of surgical prophylactic antibiotics were administered for more than 24 hours. This guideline aims to align best practices nationally and provides a framework for audit and surveillance. Method: This guideline was developed by the National Antimicrobial Stewardship Expert Panel’s National Surgical Antibiotic Prophylaxis Guideline Development Workgroup Panel, which comprises infectious diseases physicians, pharmacists, surgeons and anaesthesiologists. The Workgroup adopted the ADAPTE methodology framework with modifications for the development of the guideline. The recommended duration of antibiotic prophylaxis was graded according to the strength of consolidated evidence based on the scoring system of the Singapore Ministry of Health Clinical Practice Guidelines. Results: This National SAP Guideline provides evidence-based recommendations for the rational use of antibiotic prophylaxis. These include recommended agents, dose, timing and duration for patients undergoing common surgeries based on surgical disciplines. The Workgroup also provides antibiotic recommendations for special patient population groups (such as patients with β-lactam allergy and patients colonised with methicillin-resistant Staphylococcus aureus), as well as for monitoring and surveillance of SAP. Conclusion: This evidence-based National SAP Guideline for hospitals in Singapore aims to align practices and optimise the use of antibiotics for surgical prophylaxis for the prevention of surgical site infections while reducing adverse events from prolonged durations of SAP. Keywords: Antibiotic prophylaxis duration, antimicrobial resistance, antimicrobial stewardship, hospital-acquired infection, surgical site infections

Risk Factors of Postoperative Meningitis in Lateral Ventricular Trigone Meningiomas: A Clinical Analysis of 64 Patients

Purpose

Patients with intraventricular tumors are more susceptible to postoperative meningitis (POM) than other intracranial tumors. In this study, we explored the risk factors of POM in lateral ventricular trigone meningiomas (LVTMs).

Methods

Clinical features of 64 patients with LVTMs were analyzed. Age, gender, body mass index, medical history, intraoperative blood loss (IBL), intraventricular drainage placement, surgical duration, tumor grade, postoperative tumor cavity hemorrhage, and tumor size were included in univariate and multivariate analyses of POM.

Results

Of the 64 patients, 14 patients (21.9%) received diagnosis of POM. The univariate analysis revealed IBL ≥400 mL (odds ratio [OR], 9.012; p = 0.003), tumor size ≥50 cm³ (OR, 3.071; p = 0.080), and surgical duration ≥5 h (OR, 2.970; p = 0.085) were considered possible risk factors for POM (p < 0.10). Tumor size (R = 0.514) and surgical duration (R = 0.624) were significantly correlated with IBL (p < 0.05). In the multivariate analysis, only IBL was found to be an independent risk factor for POM.

Conclusion

The IBL ≥400 mL is independently associated with the increased risk of POM in LVTM patients. Our results demonstrate the importance of controlling IBL for preventing POM, especially in large tumors and long surgeries.

Surgical Antibiotic Prophylaxis in an Era of Antibiotic Resistance: Common Resistant Bacteria and Wider Considerations for Practice

The increasing incidence of antimicrobial resistance (AMR) presents a global crisis to healthcare, with longstanding antimicrobial agents becoming less effective at treating and preventing infection. In the surgical setting, antibiotic prophylaxis has long been established as routine standard of care to prevent surgical site infection (SSI), which remains one of the most common hospital-acquired infections. The growing incidence of AMR increases the risk of SSI complicated with resistant bacteria, resulting in poorer surgical outcomes (prolonged hospitalisation, extended durations of antibiotic therapy, higher rates of surgical revision and mortality). Despite these increasing challenges, more data are required on approaches at the institutional and patient level to optimise surgical antibiotic prophylaxis in the era of antibiotic resistance (AR). This review provides an overview of the common resistant bacteria encountered in the surgical setting and covers wider considerations for practice to optimise surgical antibiotic prophylaxis in the perioperative setting.

Evaluation of amoxicillin, metronidazole and gentamicin dosage regimens for use in antibiotic prophylaxis in colorectal surgery

OBJECTIVES

To evaluate amoxicillin, metronidazole and gentamicin dosage regimens for antibiotic prophylaxis in colorectal surgery.

METHODS

The study was conducted in 20 patients undergoing colorectal surgery. Patients received one or two doses of amoxicillin 1000 mg, metronidazole 500 mg and gentamicin 3 mg/kg ideal body weight, banded by height. Antibiotic concentrations were measured up to 7 h post dose. Population pharmacokinetic (PopPK) analysis with NONMEM followed by Monte Carlo simulation of different dosage regimens was used to estimate the PTA for potential organisms associated with surgical site infections (SSIs).

RESULTS

A median of 5 (range 3-6) concentrations were available per patient. CL and V of all antibiotics were related to weight; gentamicin CL was also related to CLCR. The administered doses maintained the desired PTA up to 8 h for the Streptococcus anginosus group but not for enterococci, Bacteroides fragilis group, MSSA, and Escherichia coli. An additional 500 mg amoxicillin every 4 h was sufficient to achieve the PTA for most relevant organisms but 2 hourly dosing was required for patients at risk of infective endocarditis. A metronidazole dose of 1000 mg was required for patients >85 kg. In patients with CLCR >50 mL/min, 5 mg/kg gentamicin (with an additional 2.5 mg/kg in prolonged surgery at 6 h) maintained PTA targets for >10 h.

CONCLUSIONS

PopPK analysis with Monte Carlo simulation identified prophylactic antibiotic regimens that would maintain the PTA for organisms associated with SSIs during short- and long-duration colorectal surgery.

Controversies in Perioperative Antimicrobial Prophylaxis

Although clinical guidelines for antibiotic prophylaxis across a wide array of surgical procedures have been proposed by multidisciplinary groups of physicians and pharmacists, clinicians often deviate from recommendations. This is particularly true when recommendations are based on weak data or expert opinion. The goal of this review is to highlight certain common but controversial topics in perioperative prophylaxis and to focus on the data that does exist for the recommendations being made.

Population Pharmacokinetic Study of the Suitability of Standard Dosing Regimens of Amikacin in Critically Ill Patients with Open-Abdomen and Negative-Pressure Wound Therapy

The aim was to assess the appropriateness of recommended regimens for empirical MIC coverage in critically ill patients with open-abdomen and negative-pressure therapy (OA/NPT). Over a 5-year period, every critically ill patient who received amikacin and who underwent therapeutic drug monitoring (TDM) while being treated by OA/NPT was retrospectively included. A population pharmacokinetic (PK) modeling was performed considering the effect of 10 covariates (age, sex, total body weight [TBW], adapted body weight [ABW], body surface area [BSA], modified sepsis-related organ failure assessment [SOFA] score, vasopressor use, creatinine clearance [CL_CR], fluid balance, and amount of fluids collected by the NPT over the sampling day) in patients who underwent continuous renal replacement therapy (CRRT) or did not receive CRRT. Monte Carlo simulations were employed to determine the fractional target attainment (FTA) for the PK/pharmacodynamic [PD] targets (maximum concentration of drug [C _max]/MIC ratio of ≥8 and a ratio of the area under the concentration-time curve from 0 to 24 h [AUC_0-24]/MIC of ≥75). Seventy critically ill patients treated by OA/NPT (contributing 179 concentration values) were included. Amikacin PK concentrations were best described by a two-compartment model with linear elimination and proportional residual error, with CL_CR and ABW as significant covariates for volume of distribution (V) and CL_CR for CL. The reported V) in non-CRRT and CRRT patients was 35.8 and 40.2 liters, respectively. In Monte Carlo simulations, ABW-adjusted doses between 25 and 35 mg/kg were needed to reach an FTA of >85% for various renal functions. Despite an increased V and a wide interindividual variability, desirable PK/PD targets may be achieved using an ABW-based loading dose of 25 to 30 mg/kg. When less susceptible pathogens are targeted, higher dosing regimens are probably needed in patients with augmented renal clearance (ARC). Further studies are needed to assess the effect of OA/NPT on the PK parameters of antimicrobial agents.

Piperacillin/Tazobactam versus Tobramycin-Based Antibiotic Prophylaxis for Type III Open Fractures

Background: Type III open fractures are associated with an infection rate as high as 50%. The optimal antibiotic for open fracture prophylaxis remains unclear, and the literature comparing the safety and efficacy of different antibiotic regimens is limited. The aim of this study was to compare the composite adverse events (AEs) in patients before and after a change in prophylactic antibiotic management for these injuries from a tobramycin- to a piperacillin/tazobactam-based regimen. Methods: This was a retrospective single-center cohort study of patients with Type III open fractures admitted from January 2010 to December 2016. Patients were included if they received either tobramycin plus cefazolin or clindamycin or piperacillin/tazobactam for fracture prophylaxis. The primary outcome was the rate of composite AEs, which included nephrotoxicity, surgical site infection (SSI), and hospital re-admission with surgical intervention. Secondary outcomes included the rate of SSI within 30 and 60 days after injury. Data were analyzed using the Student t-, Mann-Whitney U, and Fisher exact tests. Results: Eighty-five patients were included. There were 29 events in the tobramycin group compared with three in the piperacillin/tazobactam group. At 30 days, SSI had occurred in 17 patients (27.5%) in the tobramycin group and 1 patient (4.3%) in the piperacillin/tazobactam group (p = 0.033). At 60 days, SSI had occurred in three additional patients in the tobramycin group (p = 0.009). Conclusion: There was no difference in the composite AEs in the piperacillin/tazobactam compared with the tobramycin group. However, SSI within 30 and 60 days was significantly more common with tobramycin.

Ultralow anterior resection with implantation of gentamicin-collagen sponge and no defunctioning stoma: anastomotic leakage and local cancer relapse

Background Anterior resection with total mesorectal excision (TME) of ultralow rectal cancer may result in the increased risk of the anastomotic leakage (AL). The aim of this study was to evaluate the usefulness of the gentamicin-collagen sponge (GCS) for the protection against symptomatic AL and investigate association between AL and local relapse (LR). Patients and methods A series of 158 patients with ultralow rectal cancer was studied. All the patients underwent R0 sphincter-saving TME with anastomosis wrapping using GCS. In none of the cases a temporary protective stoma was constructed. Results AL rate was 3.2% (5/158) while median time to AL diagnosis was 5 days following surgery (range 3-15). There was no postoperative and leakage-related mortality. Patient age > 75 years and smoking were independent risk factors related to significantly increased AL rate: 12.5% vs. 0.8% (P = 0.0004) and 5.7% vs. 0% P = 0.043), respectively. LR was observed in 12% of cases. It was highly significantly more common and developed earlier in patients who have had AL when compared with non-AL group: 80% vs. 9% (P = 0.00001) and 8.5 vs. 17 months (P = 0.014), respectively. Conclusions Anastomosis wrapping with GCS after anterior resection with TME is a safe procedure resulting in the low incidence of anastomotic leakage which may be also associated with decreased risk of local relapse.

Compliance with perioperative prophylaxis guidelines and the use of novel outcome measures

Postoperative wound infections represent an important source of morbidity and mortality in children. Perioperative antibiotic prophylaxis has been shown to decrease the risk of developing infections and hospital guidelines surrounding antibiotic use exist to standardize patient care. Despite supporting evidence, rates of compliance with guidelines vary. Quality improvement initiatives have been introduced to improve compliance with intraoperative antibiotic guidelines. Thorough infection surveillance, including antibiotic provision in presurgical checklists, computerized voice antibiotic administration prompts, and national feedback systems are now increasingly common. Few studies have been conducted investigating the effectiveness of prophylactic antibiotics in children. Outcome measures such as morbidity and mortality and return to the operating room can be used to examine the relationship between antibiotic use and patient outcome but these measures are limited in that they occur infrequently or are subjective and difficult to measure. Metrics such as days alive out of hospital and length of hospital stay may be useful alternatives for ongoing monitoring of infections and identifying improvements in patient outcomes. Guidelines on antibiotic prophylaxis have facilitated an increase in the correct provision of perioperative antibiotics and a reduction in the incidence of postoperative infection. Measures of patient outcome such as days alive out of hospital and length of hospital stay are easy to collect and calculate but further work is needed to confirm the utility of these measures for monitoring infection rates.

Update to the Centers for Disease Control and Prevention and the Healthcare Infection Control Practices Advisory Committee Guideline for the Prevention of Surgical Site Infection (2017): A summary, review, and strategies for implementation

Surgical site infections remain a common cause of morbidity, mortality, and increased length of stay and cost amongst hospitalized patients in the United States. This article summarizes the evidence used to inform the Centers for Disease Control and Prevention and the Healthcare Infection Control Practices Advisory Committee Guideline for the Prevention of Surgical Site Infection (2017), and highlights key updates and new recommendations. We also present specific suggestions for how infection preventionists can play a central role in guideline implementation by translating these recommendations into evidence-based policies and practices in their facility.

Applying surgical antimicrobial standards in cesarean deliveries

Antimicrobial prophylaxis practices are critical to surgical site infection risk-reduction strategies. Included in these practices is antibiotic redosing following prolonged procedures or after large blood losses. Guidelines have been published by several professional associations, with most endorsing repeat antibiotic administration after an estimated blood loss of 1500 mL or following 2 half-lives of the select agent. These conventions have been widely adopted by surgeons with the exception of obstetricians at the time of cesarean delivery. This Viewpoint explores existing guidelines, reviews the data for these recommendations, and questions the tradition of abstinence from redosing in cesarean deliveries despite the burden of infection in this cohort.

Impact of national policies on the microbial aetiology of surgical site infections in acute NHS hospitals in England: analysis of trends between 2000 and 2013 using multi-centre prospective cohort data

Our study aimed to evaluate changes in the epidemiology of pathogens causing surgical site infections (SSIs) in England between 2000 and 2013 in the context of intensified national interventions to reduce healthcare-associated infections introduced since 2006. National prospective surveillance data on target surgical procedures were used for this study. Data on causative organism were available for 72% of inpatient-detected SSIs meeting the standard case definitions for superficial, deep and organ-space infections (9767/13 531) which were analysed for trends. A multivariable logistic linear mixed model with hospital random effects was fitted to evaluate trends by pathogen. Staphylococcus aureus was the predominant cause of SSI between 2000 (41%) and 2009 (24%), decreasing from 2006 onwards reaching 16% in 2013. Data for 2005-2013 showed that the odds of SSI caused by S. aureus decreased significantly by 14% per year [adjusted odds ratio (aOR) 0·86, 95% confidence interval (CI) 0·83-0·89] driven by significant decreases in methicillin-resistant S. aureus (MRSA) (aOR 0·71, 95% CI 0·68-0·75). However a small significant increase in methicillin-sensitive S. aureus was identified (aOR 1·06, 95% CI 1·02-1·10). Enterobacteriaceae were stable during 2000-2007 (12% of cases overall), increasing from 2008 (18%) onwards, being present in 25% of cases in 2013; the model supported these increasing trends during 2007-2013 (aOR 1·12, 95% CI 1·07-1·18). The decreasing trends in S. aureus SSIs from 2006 and the increases in Enterobacteriaceae SSIs from 2008 may be related to intensified national efforts targeted at reducing MRSA bacteraemia combined with changes in antibiotic use aimed at controlling C. difficile infections.

Evaluation of total body weight and body mass index cut-offs for increased cefazolin dose for surgical prophylaxis

French and American guidelines recommend increased dosage regimens of cefazolin (CFZ) for surgical prophylaxis in patients with a body mass index (BMI) ≥ 35 kg/m² or with a total body weight (TBW) ≥ 120 kg. The objective of this study was to evaluate the accuracy of these cut-offs in identifying patients who require CFZ dose adjustment. A pharmacokinetic study was conducted in patients of varying TBW and BMI who received 2 g of CFZ intravenously for prophylaxis prior to digestive surgery. Adequacy of therapy, defined as a serum concentration of unbound CFZ (fCFZ) ≥ 4 mg/L, was evaluated 180 min (T₁₈₀) and 240 min (T₂₄₀) after the start of CFZ infusion. Possible factors associated with insufficient fCFZ levels were also assessed. A P-value of <0.05 was considered statistically significant. A total of 63 patients were included in the study, categorised according to BMI (<35 kg/m², 20 patients; and ≥35 kg/m², 43 patients) and TBW (<120 kg, 41 patients; and ≥120 kg, 22 patients). All patients had adequate drug levels at T₁₈₀ but only 40/63 patients (63%) had adequate levels at T₂₄₀. At T₂₄₀, therapy was adequate in 15/20 patients (75%) and 25/43 patients (58%) with BMI <35 kg/m² and ≥35 kg/m², respectively (P = 0.20), and in 28/41 patients (68%) and 12/22 patients (55%) with TBW <120 kg and ≥120 kg, respectively (P = 0.28). No factor associated with insufficient fCFZ was identified. In conclusion, current BMI and TBW cut-offs are poor indicators of which patients could benefit from increased CFZ dosage regimens.

Preoperative administration of cephalosporins for elective caesarean delivery

INTRODUCTION

Antibiotic prophylaxis means administration of antibiotics in prevention of infections.

OBJECTIVE

To investigate the efficacy of a single dose preoperative administration of ceftriaxone and cefazolin in the prevention of intra- and postoperative infections in the parturients without high risk of inflammation.

METHODS

The first group of 45 pregnant and 4 non-pregnant women were preoperatively administered ceftriaxone in a dose of 2 g, i.v., 10 minutes before the planned surgery. The second group of 45 pregnant and 4 non-pregnant women were preoperatively administered cefazolin in a dose of 2 g i.v., 10 minutes before the planned surgery. The concentrations of antibiotics were estimated immediately and 6 hours following the operation, as well as in the amniotic fluid and umbilical cord in the group of pregnant women. The estimation of antibiotic concentration was done by the method of liquid chromatography.

RESULTS

The mean concentrations of antibiotics in the patients following the elective caesarean section were as follows: ceftriaxone--22.7 microg/I. vs cefazolin--44.8 microg/l. Six hours later, the concentration of antibiotic decreased, but the concentration of cefazolin was still over the MIC for sensitive bacteria. The mean concentrations of antibiotics following gynaecological surgery in the non-pregnant patients were as follows: ceftriaxone--12.0 microg/I vs cefazolin--30.1 microg/l. Six hours later, the concentration of antibiotic decreased.

CONCLUSION

It is most optimal to administer a single-dose of the first generation cephalosporins -cefazolin- immediately following the clamping of the umbilical cord as well as in preoperative prophylaxis in gynaecological operations.

Influence of pregnancy on one-compartmental bio-metric blood loss calculations after cesarean section and gynaecological surgery

To date there are no data in the literature on the procedure for the indirect measurement of blood loss during cesarean section, based on the post-operative drop in haemoglobin (Hb), which has been due to the lack of biometrically determined parameters for the calculation of blood volume in pregnant women. This study was therefore conducted to determine the applicability of the drop in Hb levels blood loss calculation during cesarean section, based on a model previously validated in non-pregnant women. We compared this procedure in 54 patients who underwent cesarean section and 12 non-pregnant patients subjected to gynaecological surgery. The coefficient of the regression slope for the blood volume collected during surgery and the calculated blood loss in pregnant (y=0.6286x+366) and non-pregnant patients (y=0.7605x+514) did not show any significant difference (t=1.1009, p>0.5, 95% confidence interval:-2.736, +2.473). Our study therefore demonstrated the applicability of the procedure for the indirect measurement of surgical blood loss both in pregnant and non-pregnant women.