Changes of the microbiological spectrum and antibiotic resistance pattern in postoperative spinal implant infections with multiple culture-positive revision surgeries

Abstract

BACKGROUND CONTEXT

In severe cases of postoperative spinal implant infections (PSII) multiple revision surgeries may be needed. Little is known if changes in the microbiological spectrum and antibiotic resistance pattern occur between revision surgeries.

PURPOSE

Analysis of the microbiological spectrum and antibiotic resistance pattern in patients with multiple revision surgeries for the treatment of PSII

STUDY DESIGN

Retrospective database analysis.

PATIENT SAMPLE

Between 01/2011 and 12/2018, 103 patients underwent 248 revision surgeries for the treatment of PSII. Twenty patients (19.4%) who underwent multiple revision surgeries for PSII were included in this study.

OUTCOME MEASURES

Microbiological spectrum, antibiotic resistance pattern.

METHODS

A retrospective analysis of a prospectively maintained single center spine infection database was performed with a minimum follow-up of 3 years. Overall, 20 patients (six male/14 female) underwent 82 revisions for PSII (median 3; range 2–12). There were 55 of 82 (67.1%) procedures with a positive microbiological result. Microbiological analysis was performed on tissue and implant sonication fluid. Changes in microbial spectrum and antibiotic resistance pattern between surgeries were evaluated using Chi-Square and Fisher's exact test.

RESULTS

In total, 74 microorganisms (83.3% gram-positive; 10.8% gram-negative) were identified. The most common microorganisms were Staphylococcus epidermidis (18.9%) and Cutibacterium acnes (18.9%). All S. epidermidis identified were methicillin-resistant (MRSE). Overall, there were 15 of 55 (27.3%) polymicrobial infections. The microbiological spectrum changed in 57.1% (20/35) between the revision stages over the entire PSII period. In 42.9% (15/35) the microorganism persisted between the revision surgeries stages. Overall, changes of the antibiotic resistance pattern were seen in 17.4% (8/46) of the detected microorganisms, comparing index revision and all subsequent re-revisions. Moreover, higher resistance rates were found for moxifloxacin and for ciprofloxacin at first re-revision surgery compared with index PSII revision. Resistances against vancomycin increased from 4.5% (1/23) at index PSII revision to 7.7% (2/26) at first re-revision surgery.

CONCLUSIONS

Changes of the microbiological spectrum and the resistance pattern can occur in patients with severe PSII who require multiple revision surgeries. It is important to consider these findings in the antimicrobial treatment of PSII. The microbiological analysis of intraoperative tissue samples should be performed at every revision procedure for PSII.

Introduction

Postoperative spinal implant infections (PSII) after spinal fusion pose significant clinical challenges and can result in high postoperative morbidity, mortality, and increased health care costs [1]. Recent studies demonstrate a higher incidence of PSII in patients who undergo a presumed aseptic revision surgery compared to primary instrumentation [2]. The surgical management of PSII includes surgical debridement-irrigation, antibiotic therapy, and implant retention (DAIR) for early onset infections and implant removal for late-onset infections [3]. In severe cases, single revision surgery may not be sufficient and multiple revisions are needed [4]. Especially, polymicrobial infections are of concern due to limited treatment options and a higher risk of treatment failure [5]. Persistent infections occur due to unsuccessful eradication of the causative microorganisms, which can lead to multidrug resistances due to prolonged administration of antibiotics [6]. There are a number of studies on the microbiological spectrum of patients with PSII that show a wide range of causative pathogens, with Staphylococcus epidermidis and Cutibacterium acnes as the most prevalent microorganisms. Especially, in late-onset infections after instrumented fusion, S. epidermidis seems to be one of the most involved microorganisms [2,7].

In periprosthetic infection (PJI) of the hip and knee joint it was shown that changes of the microbiological profile are common in culture-positive revisions at different revision stages [8,9]. Isolation of different microorganisms at a later septic procedure might be due to eradication of the initially detected microorganism and acquirement of an additional microorganism or due to an undetected polymicrobial infection at first stage procedure. If the same microorganism is detected at later revision procedure it is most likely due to persistence of the initially detected microorganism [10]. However, there is little data on potential changes of the microbiological spectrum and antibiotic resistance pattern in patients who underwent multiple revision surgeries for PSII [6].

Therefore, the aim of this study was to perform a retrospective single center study to analyze the microbiological spectrum and resistance patterns in patients with confirmed PSII after multiple revision surgeries with positive culture results. Furthermore, changes of the microbiological spectrum, distribution of mono- versus polymicrobial infections, and changes of the antimicrobial resistance profile in persistent microorganisms were evaluated.