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Polymicrobial flora, gram-negative organisms seen in pelvic endoprostheses affected by infection following tumor resection
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In patients with pelvic endoprostheses affected by infection following tumor resection, infections were mostly polymicrobial flora, caused by gram-negative microorganisms and may be correlated with intestinal flora, according to recently published results.
“The epidemiology of micro-organisms cultured after infection of pelvic reconstructions differ fundamentally from mono-bacterial gram-positive causes of conventional prosthetic joint infections. Therefore, current prophylactics and empiric treatment may need to be changed,” Philip T.J. Sanders, MD, told Healio.com/Orthopedics.
Researchers identified 70 patients who underwent endoprosthetic reconstruction in periacetabular tumor resection. Of the 70 patients, 18 patients developed an infection. The median follow-up was 66 months. Investigators recorded the microorganisms isolated during first debridement. The number of reoperations for ongoing infection, antimicrobial treatment strategy and the outcome of the treatment were also recorded.
Results showed 18 patients with infection had polymicrobial infection. In 12 patients, investigators identified Enterobacteriaceae on culture. The identified pathogen was gram-negative in 26 instances out of the 42 times a microorganism was isolated. Microorganisms correlated with intestinal flora were identified 32 times.
There were nine patients who had the original implant in situ at the latest follow-up, of which two patients had a fistula and two patients received suppressive antibiotic therapy. The original implant had been removed in the nine remaining patients, of which three patients had a second implant in situ. Secondary reconstruction was not needed in the six-remaining patients. – by Monica Jaramillo
Disclosures: The authors report no relevant financial disclosures.
Perspective
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Javad Parvizi, MD, FRCS
Sanders and colleagues described the microbiological trends and treatment outcomes of 70 patients undergoing pelvic endoprosthetic reconstruction over a 14-year period. At a median 5.5-year follow-up, 26% of patients developed an infection, and the majority of these (78%) were polymicrobial. Sixty-two percent of cultures isolated a Gram-negative organism. Of note, 76% of all positive cultures grew microbes associated with intestinal flora. The authors therefore suggest a “leaky gut translocation” hypothesis for infections affecting pelvic endoprostheses and conclude that standard empiric mono-agent antibiotic prophylaxis regimens may need to be modified in this patient subset.
These culture data support two emerging paradigm shifts regarding our understanding periprosthetic joint infection: (1) the potential role of the gut microbiome in disease, and (2) that PJI is often polymicrobial in nature. Our understanding over recent months, mainly augmented by molecular sequencing technologies, echoes these trends in pathogenesis at the microbial DNA and RNA level.
Further, the authors raise an important consideration regarding the spectrum of antibiotic prophylaxis. The polymicrobial flora found in infected endoprosthetic reconstructions may indeed justify the use of a broader spectrum of prophylaxis aimed at Gram-negative bacteria. However, one caveat to this deduction is the strength of conclusions that can be drawn from a cohort of 19 infected cases. In an era of antibiotic stewardship, further work is needed. That said, the observational trend and rationale presented is indeed compelling.
Philadelphia
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