Microbial landscape in different types of periprosthetic hip joint infection

Introduction Due to the steady increase in the number of primary total hip arthroplasties, the problem of eliminating periprosthetic joint infection (PJI) has become pressing. The rise of antimicrobial-resistant PJI pathogens significantly complicates and prolongs treatment, contributing to the development of chronic infection, sometimes with latent clinical manifestations. The aim of this study was to identify the microbial landscape characteristics in different types of hip joint PJI. Materials and Methods Microbiological studies of 96 patients with hip joint PJI were analyzed: Group 1 (n = 16) with type I PJI; Group 2 (n = 80) with type II and type III PJI. Patients in Group 1 underwent the DAIR procedure and those in Group 2 underwent two-stage revision hip replacement. Results A total of 103 microbial isolates were obtained from 96 patients: 16 (15.5 %) Gr(–) and 87 (84.5 %) Gr(+). Among Gr(+), MRSA, MRSE, and MRSH were detected in 18 isolates, and among Gr(–), ESBL+ was detected in 16 isolates. The predominant pathogens in the PJI structure were S. aureus (52.9 %), S. epidermidis (19.5 %), E. cloacae (37.5 %), P. aeruginosa (18.6 %), and E. coli (18.6 %). Associations were more common in type 1 PJI (25 %) than in chronic forms (18.4 %). Microbial associations were detected in 20 cases (19.4 %). Culture-negative infection (CNI) was detected in 16 patients (16.7 %) in both groups. Relapse of PJI in patients with microbial associations occurred in three cases (15 %). In CNI cases, recurrence developed in four cases (25 %). Discussion The growth of Gr(–) flora in early PJI exceeded that in the chronic one: 31.3 % and 9.2 %, respectively. DAIR is ineffective in such conditions. S. aureus, as a causative agent of bone and joint infections, exists in a quasi-dormant state which contributes to chronicity. Conclusion Gram-negative microorganisms and their associations dominate in the etiology of early PJI (type I), while gram-positive pathogens predominated in chronic types (types II and III). Culture-negative infection was a more common cause of early PJI than of chronic types (25.0 % and 16.1 %, respectively). No statistically significant differences were found between the groups in the detection of methicillin-resistant staphylococci or gram-negative bacteria ESBL+.