Identification of infectious species after resection of soft‐tissue sarcomas

Abstract

Background Pathogenic species in deep tissue infections after soft‐tissue sarcoma (STS) resection is largely unstudied, particularly the role of anaerobic bacteria, risks factors for those pathogens, and the time course of infection presentation. Methods Retrospective analysis of 64 patients requiring operative debridement for deep tissue infection after STS resection was undertaken to identify infectious species and study risk factors for anaerobic infections. Kaplan–Meier methods examined the time course of infection presentation. Results STS subtypes were most commonly pleomorphic STS, myxofibrosarcoma, and undifferentiated STS. Staphylococcus aureus was the most common organism isolated (56%). Twenty (31%) infections were positive for ≥1 anaerobic organism. Twelve gram‐positive and 10 gram‐negative aerobic organisms were isolated. Most (90%) anaerobic‐containing infections were polymicrobial, vs 52% of purely aerobic infections. No significant risk factors for anaerobic infections were identified. Median time from tumor resection until debridement was significantly greater for anaerobic infections (54.5 days) than for purely aerobic infections (29.5 days; P = 0.004), a difference so pronounced that using “presentation after 53 days” as a proxy for the presence of anaerobic pathogens had an accuracy of 81%. Conclusions Because polymicrobial and anaerobic bacterial infections are common, we strongly support antibiotic use with anaerobic coverage at debridement, particularly for infections presenting later.

Is the Addition of Anaerobic Coverage to Perioperative Antibiotic Prophylaxis During Soft Tissue Sarcoma Resection Associated With a Reduction in the Proportion of Wound Complications?

“…Given the rarity of these infections compared with major wound complications, it is possible that this lack of association was because of the small number of such infections and that a larger study may detect an association. Regardless, the present study highlights the nontrivial number of polymicrobial and anaerobic infections after these surgeries that has been previously reported [26, 35]. The difficulty in culturing anaerobic bacteria [20] and the suboptimal rate of treatment success versus anaerobic bacteria despite appropriate medical and surgical intervention [36] reinforces the potential benefit of deep tissue cultures at wound debridement or drainage to better tailor therapeutic antibiotics in the case of surgical site infection.…”

“…It is not known whether the atypical infections after soft tissue sarcoma resection result similarly from seeding at the time of resection or from hematogenous seeding in the subacute period after surgery. Anaerobic-containing infections in this population present later than purely aerobic infections, although whether this is because of late hematogenous seeding of the former or is simply owing to the slower-growing, less virulent nature of those organisms is not known [26]. The fact that there was a decreased proportion of major wound complications in the current study was associated with changes to the perioperative antibiotic regimen lends evidence to intraoperative rather than late hematogenous seeding as the mechanism.…”

“…Many factors associated with major wound complications have been reported, including patient characteristics such as age, BMI, smoking, and diabetes status, as well as tumor characteristics such as size, location (lower extremity), and proximity of the resected margin to skin [2,5,9,11,18,19,22,23,26]. Treatment variables such as EBRT (particularly preoperative) and surgical closure methods also have a major effect on major wound complications [19,22,23].…”

“…Postoperative major wound complications are common after surgical resection of soft tissue sarcomas, with wound complications reported to occur in 10% to 48% in the evidence [1,5,7,11,18,19,26]. A recent systematic review cited an incidence of major wound complications of 30.2% and an overall reoperation incidence of 13.4% [29].…”

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Background Wound complications are common after resection of soft tissue sarcomas, with published infection rates ranging from 10% to 35%. Multiple studies have reported on the atypical flora comprising these infections, which are often polymicrobial and contain anaerobic bacteria, and recent studies have noted the high prevalence of anaerobic bacterial infections after soft tissue sarcoma resection [26,35]. Based on this, our institution changed clinical practice to include an antibiotic with anaerobic coverage in addition to the standard first-generation cephalosporin for prophylaxis during soft tissue sarcoma resections.

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