Broad-spectrum Antibiotic Prophylaxis in Tumor and Infected Orthopedic Sur-gery - the Prospective-randomized, Microbiologist-blinded, Stratified, Superiority Trials - BAPTIST Trials

The perioperative antibiotic prophylaxis is evidence-based for the majority of orthopedic surgeries. While the debate of its duration and timing (single-dose versus triple-dose; before or after the intraoperative microbiological sampling) may continue, no clinicians doubt on the efficiency of the recommended prophylactic agents; that are mostly 1st or 2nd-generation cephalosporins, co-amoxiclav or other exceptional agents in cases of (pseudo)-allergy. However. and traditionally, up to the half of all detected pathogens of orthopedic SSI's are not covered by the prior prophylactic regimens: e.g. SSIs due to methicillin-resistant cocci or non-fermenting Gram-negative rods in orthopedic surgery.

Additionally, orthopedic surgeons operating selected patient populations (neoplasms, open fractures, postoperative wound dehiscence9, diabetic foot infections or already infected body sites) experience a high risk of prophylactic-resistant pathogens, or pathogens resistant to current therapeutic antibiotics regimens. At least 10% of all new intraoperative tissue samples, during iterative surgical debridement, yield (new) pathogens unknown to the clinicians.

This is due to selection by prophylactic or therapeutic antibiotics, which only kill the previously detected pathogens, but left over newly introduced contaminants, remnant parts of partially-diagnosed polymicrobial infections; ultimately leading to a new SSIs occurring during therapy for the first infection at the orthopedic site. This selection is unpredictable involving both Gram-positive skin pathogens as well as (multi) resistant Gram-negative rods.From a microbiological point of view, only a maximal Gram-negative coverage, alongside with a large Gram-negative coverage, would cover these selections.

The literature is in-existing how to prevent these selections. Most clinicians just continue with the standard prophylactic recommendation, or the current thera-peutic antibiotic regimen. Theoretically, clinicians cannot exclude that these selected patient populations eventually might profit from a broad-spectrum prophylaxis.

The BAPTIST trials only concern the perioperative antibiotic prophylaxis in selected situations of orthopedic surgery: tumor surgery, debridement for postoperative dehiscent wounds, debridement under antibiotics, open fractures, skin colonization with multidrug-resistant bacteria, plus, as a control; spine surgery in selected multimorbid patients. The investigators alternately randomize the standard prophylaxis (or by continuing the current antibiotic treatment) to the additional broad-spectrum single-shot of vancomycin 1g IV & single-shot of gentamicin 5 mg/kg intravenously; before an eventual intraoperative sampling. End-of-Treatment (EOT) and/or Test-of-Cure (TOC) occur latest at the 6-week's surgical control visit. The rest of the hospital stay, treatment, the use of negative-pressure vacuum therapy, other interventions, local antibiotic therapies; therapies or procedure are at the discretion of the treating clinicians.