Analysis of the microbial landscape in patients with periprosthetic infection of the hip joint

Introduction The concept of the pathogenesis of periprosthetic joint infection (PJI) is the ability of pathogenic microorganisms to colonize the surfaces of implants, which are infected during the surgery or by hematogenous dissemination of bacteria. It causes poor results of PJI treatment. Microbiological identification of pathogen species is the gold standard in the diagnosis of PJI. Purpose To assess the etiology of the infectious process in patients with periprosthetic hip joint infection. Methods The study analyzed revision interventions (n = 294) for PJI of the hip joint performed within the period from 2010 throughout 2021. A total of 147 patients were operated on: 56 % (n = 82) were men and 4 % (n = 65) were women. At the time of hospitalization, the fistula PJI type was diagnosed in 71 % (n = 105); 20 % (n = 29) had edema and hyperemia of the postoperative suture area, and 9 % (n = 13) of cases had open wounds. The object of the study was bone and soft tissue samples obtained during excision of the infected material, as well as removed implant components. Cultures were grown on dense nutrient media. Bacterial cultures were identified by generally accepted methods using TB Expression (BioMerieux, France) and Walk Away 40 (USA) bacteriological analyzers. Results The etiology of periprosthetic infection was identified in the majority of patients (93 %), while pathogens could not be detected in the remaining cases. Bacteriological analysis revealed microbial associations in 31 % of patients, gram-positive microflora in 52 % of patients, and gram-negative microflora in 10 %. Discussion The most common types of microorganisms are gram-positive bacteria with a tendency for resistant strains to grow. Gram-negative bacteria are isolated in joint infection, but less frequently. The results demonstrate isolated gram-negative cultures in 10 % of cases. The second most common cause of periprosthetic joint infection is polymicrobial infection, which was detected in 31 % of cases. Microbial associations occurr in 10–45 % of cases; such a clinical situation at the start of treatment complicates the empirical choice of drugs for antibacterial therapy. Conclusions Microbiological study allowed identification of the etiology of the infectious process in 93 % of patients. In more than half of the cases (52 %), the cause of implant-associated infection is grampositive microflora, and in 31 % of cases are microbial associations. Reinfection was noted in 41 % of cases in polymicrobial patients.