Deep surgical site infections following double-dose perioperative antibiotic prophylaxis in adult obese orthopedic patients

Surgical Antibiotic Prophylaxis Dosing in Adult Patients with Obesity: A Comprehensive Review of Pharmacokinetic and Pharmacodynamic Data

Surgical antibiotic prophylaxis is an important measure to prevent postoperative surgical site infections. Current guideline recommendations do not treat obesity specifically, although it can affect pharmacokinetics and pharmacodynamics. The objective of this review was to synthesize current evidence on the need for obesity-related dosing adjustments in surgical antibiotic prophylaxis. MEDLINE and Cochrane Library were searched for studies investigating antibiotic prophylaxis dosing in surgical patients with obesity. Outcomes of interest were pharmacokinetic parameters such as plasma and interstitial fluid concentrations, area under the concentration time curve in plasma and in interstitial fluid, and other pharmacokinetic measures. Thirty studies investigating cefazolin, cefoxitin, cefuroxime, piperacillin/tazobactam, meropenem, ertapenem, metronidazole, vancomycin, ciprofloxacin, and gentamicin were included in this analysis. Except for metronidazole, cefoxitin, and gentamicin, there is currently no evidence suggesting the need for dosing adjustments.

[Perioperative antibiotic prophylaxis in obesity]

BACKGROUND

In terms of perioperative infections, arthroplasty for obese patients represents a high-risk procedure. Correct antibiotic prophylaxis is a central pillar of infection prophylaxis. Studies showed increased infection rates if an antibiotic other than cefazolin was administered for prophylaxis. In patients with anamnestic penicillin allergy, an existing allergy is extremely rare, and the presence of cross-allergies to cephalosporins is similarly rare. Consequently, every effort should be made to administer a first- or second generation cephalosporin such as cefazolin.

DOSAGE

Whether the dosage of antibiotic prophylaxis should be adjusted to the body weight remains unclear due to the limited data available: case series showed increased infection rates when cefazolin was underdosed and recommended increasing the dose to 3 g if the body weight exceeds 120 kg. However, no studies with a higher level of evidence exist. Published studies on the effective antibiotic levels in the tissue remain contradictory with regard to possible weight-dependent dose adjustments. Similarly, there is insufficient data on whether local intraoperative antibiotic prophylaxis may be useful in obese patients. By contrast, there is no evidence for a positive benefit of double prophylaxis with two different antibiotics or prolonged postoperative antibiotic prophylaxis in obesity.

CONCLUSION

In summary, the data on antibiotic prophylaxis is generally insufficient, especially when focussing on possible dose adjustments in obesity. The well-timed administration of a cephalosporin such as cefazolin represents the golden standard in orthopedics and trauma surgery. A possible dose adjustment to 3 g for a body weight over 120 kg appears reasonable considering the low costs and the broad therapeutic window and is therefore recommended in the current AWMF S3 guideline.

General skin and nasal decolonization with octenisan® set before and after elective orthopedic surgery in selected patients at elevated risk for revision surgery and surgical site infections-a single-center, unblinded, superiority, randomized controlled trial (BALGDEC trial)

BACKGROUND

The preoperative body surface and nasal decolonization may reduce the risk of surgical site infections (SSI) but yields conflicting results in the current orthopedic literature.

METHODS

We perform a single-center, randomized-controlled, superiority trial in favor of the preoperative decolonization using a commercial product (octenidine® set). We will randomize a total number of 1000 adult elective orthopedic patients with a high risk for SSI and/or wound complications (age ≥ 80 years, chronic immune-suppression, American Society of Anesthesiologists score 3-4 points) between a decolonization (octenisan® wash lotion 1 × per day and octenisan® md nasal gel 2-3 × per day; during 5 days) and no decolonization. Decolonized patients will additionally fill a questionnaire regarding the practical difficulties, the completeness, and the adverse events of decolonization. The primary outcomes are SSI and revision surgeries for postoperative wound problems until 6 weeks postoperatively (or 1 year for surgeries with implants or bone). Secondary outcomes are unplanned revision surgeries for non-infectious problems and all adverse events. With 95% event-free surgeries in the decolonization arm versus 90% in the control arm, we formally need 2 × 474 elective orthopedic surgeries included during 2 years.

DISCUSSION

In selected adult orthopedic patients with a high risk for SSI, the presurgical decolonization may reduce postoperative wound problems, including SSI.

TRIAL REGISTRATION

ClinicalTrial.gov NCT05647252. Registered on 9 December 2022.

PROTOCOL VERSION

2 (5 December 2022).

Broad-spectrum antibiotic prophylaxis in tumor and infected orthopedic surgery-the prospective-randomized, microbiologist-blinded, stratified, superiority trials: BAPTIST Trials

BACKGROUND

The perioperative antibiotic prophylaxis with 1st or 2nd generation cephalosporins is evidence-based in orthopedic surgery. There are, however, situations with a high risk of prophylaxis-resistant surgical site infections (SSI).

METHODS

We perform a superiority randomized controlled trial with a 10% margin and a power of 90% in favor of the broad-spectrum prophylaxis. We will randomize orthopedic interventions with a high risk for SSI due to selection of resistant pathogens (open fractures, surgery under therapeutic antibiotics, orthopedic tumor surgery, spine surgery with American Society of Anesthesiologists (ASA) score ≥ 3 points) in a prospective-alternating scheme (1:1, standard prophylaxis with cefuroxime versus a broad-spectrum prophylaxis of a combined single-shot of vancomycin 1 g and gentamicin 5 mg/kg parenterally). The primary outcome is "remission" at 6 weeks for most orthopedic surgeries or at 1 year for surgeries with implant. Secondary outcomes are the risk for prophylaxis-resistant SSI pathogens, revision surgery for any reason, change of antibiotic therapy during the treatment of infection, adverse events, and the postoperative healthcare-associated infections other than SSI within 6 weeks (e.g., urine infections or pneumonia). With event-free surgeries to 95% in the broad-spectrum versus 85% in the standard prophylaxis arm, we need 2 × 207 orthopedic surgeries.

DISCUSSION

In selected patients with a high risk for infections due to selection of prophylaxis-resistant SSI, a broad-spectrum combination with vancomycin and gentamycin might prevent SSIs (and other postoperative infections) better than the prophylaxis with cefuroxime.

TRIAL REGISTRATION

ClinicalTrial.gov NCT05502380. Registered on 12 August 2022. Protocol version: 2 (3 June 2022).

Perioperative Urinary Catheter Use and Association to (Gram-Negative) Surgical Site Infection after Spine Surgery

This study evaluates potential associations between the perioperative urinary catheter (UC) carriage and (Gram-negative) surgical site infections (SSIs) after spine surgery. It is a retrospective, single-center, case-control study stratifying group comparisons, case-mix adjustments using multivariate logistic regression analyses. Around half of the patients (2734/5485 surgeries) carried a UC for 1 day (median duration) (interquartile range, 1-1 days). Patients with perioperative UC carriage were compared to those without regarding SSI, in general, and Gram-negative, exclusively. The SSI rate was 1.2% (67/5485), yielding 67 revision surgeries. Gram-negative pathogens caused 16 SSIs. Seven Gram-negative episodes revealed the same pathogen concomitantly in the urine and the spine. In the multivariate analysis, the UC carriage duration was associated with SSI (OR 1.1, 95% confidence interval 1.1-1.1), albeit less than classical risk factors like diabetes (OR 2.2, 95%CI 1.1-4.2), smoking (OR 2.4, 95%CI 1.4-4.3), or higher ASA-Scores (OR 2.3, 95%CI 1.4-3.6). In the second multivariate analysis targeting Gram-negative SSIs, the female sex (OR 3.8, 95%CI 1.4-10.6) and a UC carriage > 1 day (OR 5.5, 95%CI 1.5-20.3) were associated with Gram-negative SSIs. Gram-negative SSIs after spine surgery seem associated with perioperative UC carriage, especially in women. Other SSI risk factors are diabetes, smoking, and higher ASA scores.

Risk Factors for Surgical Site Infections After Single-Level Anterior Lumbar Interbody Fusion

Abstract Background: Anterior lumbar interbody fusion (ALIF) has become an increasingly popular and effective treatment modality for various conditions of the lumbar spine. However, complications after this procedure can be costly. Surgical site infections (SSIs) are one of these types of complications. The present study identifies independent risk factors for SSI after single-level ALIF to identify high-risk patients better. Patients and Methods: The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database was queried to identify single-level ALIF patients from 2005 to 2016. Multilevel fusions and non-anterior approach procedures were excluded. Mann-Pearson χ² tests analyzed categorical variables, whereas one-way analysis of variance (ANOVA) and independent t-tests analyzed differences in mean values of continuous variables. Risk factors for SSI were identified via a multivariable logistic regression model. A receiver operating characteristic (ROC) curve was generated utilizing the predicted probabilities. Results: A total of 10,017 patients met inclusion criteria; 80 (0.80%) had developed SSI and 9,937 (99.20%) had not. On multivariable logistic regression models, class 3 obesity (p = 0.014), dialysis (p = 0.025), long-term steroid use (p = 0.010), and wound classification 4 (dirty/infected) (p = 0.002) all independently increased the risk for SSI in single-level ALIF. The area under the receiver operating characteristic curve (AUROC; C-statistic) was 0.728 (p < 0.001), indicating relatively strong reliability of the final model. Conclusions: Several independent risk factors including obesity, dialysis, long-term steroid use, and dirty wound classification all increased risk for SSI after single-level ALIF. By identifying these high-risk patients, surgeons and patients can have more informed pre-operative discussions. In addition, identifying and optimizing these patients prior to operative intervention may help to minimize infection risk.

Weight-based cefuroxime dosing provides comparable orthopedic target tissue concentrations between weight groups - a microdialysis porcine study

Antibiotic prophylaxis is a key element in prevention of surgical site infections. For the majority of orthopedic procedures, antibiotic administration follows fixed dosing regimens irrespective of weight. However, this may result in insufficient antibiotic target tissue concentrations and higher risk of surgical site infections in obese individuals. The aim of this study was to investigate the effect of weight-based cefuroxime dosing on plasma and target tissue concentrations. Eighteen female pigs were allocated into three groups differentiated by weight: 53-57 kg, 73-77 kg, and 93-97 kg. Microdialysis catheters were placed for continuous sampling in bone, muscle, and subcutaneous tissue during an 8h sampling interval. Blood samples were collected as reference. Cefuroxime was administered intravenously as a bolus according to weight (20 mg/kg). The primary endpoint was the time above the cefuroxime minimal inhibitory concentration for Staphylococcus aureus (T > MIC (4 μg/mL)). Comparable target tissue T > MICs (4 μg/mL) were found between weight groups. Mean T > MIC ranged between 116-137 min for plasma, 118-154 min for bone, 109-146 min for the skeletal muscle, and 117-165 min for subcutaneous tissue across the groups. Weight-based cefuroxime (20 mg/kg) dosing approach provides comparable perioperative plasma and target tissue T > MIC (4 μg/mL) in animals between 50-100 kg body weight, and thus a comparable prophylaxis of surgical site infections.

Impact of a total lockdown for pandemic SARS-CoV-2 (Covid-19) on deep surgical site infections and other complications after orthopedic surgery: a retrospective analysis

BACKGROUND

A total lockdown for pandemic SARS-CoV-2 (Covid-19) entailed a restriction of elective orthopedic surgeries in Switzerland.  While access to the hospital and human contacts were limited, hygiene measures were intensified. The objective was to investigate the impact of those strict public health guidelines on the rate of intra-hospital, deep surgical site infections (SSI), wound healing disorders and non-infectious postoperative complications after orthopedic surgery during the first Covid-19 lockdown.

METHODS

In a single-center study, patients with orthopedic surgery during the first Covid-19 lockdown from March 16, 2020 to April 26, 2020 were compared to cohorts that underwent orthopedic intervention in the pre- and post-lockdown periods of six months each. Besides the implementation of substantial public health measures (promotion of respiratory etiquette and hand hygiene), no additional infection control bundles have been implemented.

RESULTS

5791 patients were included in this study. In multivariate Cox regression analyses adjusting for the large case-mix, the lockdown was unrelated to SSI (hazard ratio (HR) 1.6; 95% confidence interval (CI) 0.6-4.8), wound healing disorders (HR 0.7; 95% CI 0.1-5.7) or other non-infectious postoperative complications (HR 0.7, 95% CI 0.3-1.5) after a median follow-up of seven months.

CONCLUSION

The risks for SSI, wound healing disorders and other complications in orthopedic surgery were not influenced by the extended public health measures of the total Covid-19 lockdown. Trial registration BASEC 2020-02646 (Cantonal Ethics Commission Zurich).

LEVEL OF EVIDENCE

Level III.