Microbiological spectrum of causative agents of implant-associated infection in the treatment of complications of transpedicular fixation of the spine using the negative pressure method

Abstract

Objective. To analyze the leading pathogens of implant-associated infection (IAI) after spinal surgery and identification of trends in the change in the pattern of microorganisms at the stages of treatment using the negative pressure method (NPWT systems).Material and Methods. The results of microbiological cultures of 25 patients with IAI of the spine were studied. The frequency of occurrence of Gram-positive and Gram-negative pathogens was estimated. The leading pathogens in the species spectrum were identified. Changes in the structure of identified microorganisms were studied at various time intervals of treatment.Results. A total of 136 microbiological studies were performed in 25 patients at the stages of treatment with the negative pressure method, with the identification of microorganisms in 127 (93.3 %) cases. The frequency of gram-negative microflora was 50.0 %, gram-positive – 42.6 %, Candida sp. – 0.7%, in 15.4 % microbial associations with the dominance of gram-negative microflora were identified at all periods of treatment. Not only the diversity of the isolated flora was noted (E. faecalis – 16.5 %, P. aeruginosa – 14.2 %, K. pneumoniae – 11.0 %, S. aureus and A. baumannii – 9.4 % each and S. epidermidis – 8.6 %), but also changes in the spectrum of flora at the stages of treatment: on the 1st and 2nd weeks from the first debridement intervention and the installation of the NPWT system, E. faecalis was most often detected, on the 3rd and 4th weeks – P. aeruginosa and A. baumannii, during the 2nd month – E. faecalis and P. aeruginosa, later – gram-negative bacteria against the background of an increase in the incidence of K. pneumoniae. The frequency of verification of other species of microorganisms had no statistically significant differences. Microbial associations were found from the 2nd month of treatment. The change in pathogens was noted in 72 % of cases during the treatment of IAI of the spine. On average, this treatment required 7–8 NPWT dressing changes per patient. This method of treatment made it possible to achieve both negative results of microbiological examination and stable relief of the infectious process.Conclusion. IAI, which complicates surgical interventions on the spine, is characterized by a change in pathogens during treatment, which requires not only multiple debridement with the replacement of the NPWT dressing, but also adequate long-term rational (etiologically justified) antibacterial therapy, based on the control of data on both the spectrum and on microbial resistance.