Difficult-to-treat pathogens significantly reduce infection resolution in periprosthetic joint infections

Abstract

Periprosthetic joint infection (PJI) is a feared complication after arthroplasty. Our hypothesis was that PJI caused by difficult-to-treat (DTT) pathogens has a worse outcome compared with non-DTT PJI.

Routine clinical data on 77 consecutive patients with confirmed PJI treated with 2-stage exchange arthroplasty were placed in DTT and non-DTT PJI groups and analyzed. The main outcome variable was that the patient was definitively free of infection after 2 years.

We found definitive infection resolution in 31 patients in the DTT group (68.9%) and 28 patients (87.5%) in the non-DTT group (P < 0.05). The necessity for revision surgery until assumed resolution of infection was significantly more frequent in the DTT group with 4.72 ± 3.03 operations versus 2.41 ± 3.02 operations in the non-DTT group (P < 0.05).

PJI caused by DTT bacteria is associated with significantly higher numbers of revision operations and significantly inferior definitive infection resolution.

Introduction

Periprosthetic joint infection (PJI) after total joint arthroplasty (TJA) is a severe complication that remains a core problem in orthopedic surgery (Gollwitzer et al., 2006; Senthi et al., 2011). The prevalence of PJI is estimated to be 0.4–2% in primary TJA (Peersman et al., 2001), rising to 5–15% in high-risk patients and in revision surgery (Jamsen et al., 2009; Zimmerli et al., 2004).

To guarantee optimal pathogen detection and subsequently the most effective antimicrobial therapy, most centers prefer a 2-stage revision procedure (Jamsen et al., 2009; Zimmerli et al., 2004), which offers the benefit of using intraoperatively obtained specimens to culture the pathogenic trigger and adjust the antibiotic therapy accordingly. Furthermore, a second surgical debridement during reimplantation enables additional reduction of the microbial load (Zimmerli et al., 2004).

Decisions on suitable therapy for PJI should always consider both microbiological and surgical aspects, as the surgical eradication of the pathogen must be combined with effective and targeted antimicrobial therapy (Sia et al., 2005). Taking this into account, the Liestal concept, a therapy algorithm used for hip and knee joint prostheses and suggested for other PJIs, indicates the duration of the infection, the stability of the implant, the condition of the soft tissue, and the severity of the detected pathogen (Laffer et al., 2006; Zimmerli and Ochsner, 2003). In this context, the so-called difficult-to-treat (DTT) pathogens hold an important position in the treatment of PJI (Zimmerli et al., 2004). These pathogens are characterized by the absence of highly bioavailable oral antimicrobial therapy (Laffer et al., 2006; Zimmerli et al., 2004; Zimmerli and Ochsner, 2003). To date, only limited data are available on the outcome of PJI due to DTT pathogens, with some studies only observing individual pathogens such as methicillin-resistant Staphylococcus aureus or methicillin-resistant Staphylococcus epidermidis (Bradbury et al., 2009; Tornero et al., 2013; Walls et al., 2008). Furthermore, to the best of our knowledge, no publications have identified risk factors affecting the outcome of PJI depending on the medical treatment in cases where DTT pathogens are present.

Following this rationale and considering the deficiency in evidence, we investigated (1) whether the presence of DTT bacteria affects the outcome in terms of the rate of patients graded as definitively free of infection at a minimum follow-up period of 2 years (Laffer et al., 2006) in patients with confirmed PJIs of TJAs treated with 2-stage exchange arthroplasty and (2) which risk factors are associated with a DTT PJI.

Our primary hypothesis was that a PJI with a DTT pathogen worsens the outcome regarding the resolution of infection. Our secondary hypothesis was that local or systemic risk factors could be identified that are associated with the occurrence of PJI with a DTT PJI.