The aims of the treatment of a patient with PJI are to eradicate the infection, alleviate the pain and, at the same time, restore the joint's function. This makes PJI different from other infections in which the eradication of the infection alone may be sufficient for evaluating a given therapeutic strategy. In the case of PJI, all three goals must be considered in combination, since sometimes achieving one of these targets (i.e., eradication of the infection) may interfere with another (i.e., achieving a satisfactory functional outcome). This situation increases the complexity of the management of these patients, has a deep impact on the therapeutic decisions, and makes the interpretation of the literature difficult, since there is no standardized definition of therapeutic success.

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  Due to the complexity of patients with PJI, they should be attended at multidisciplinary units.(C-III)

The main medical and surgical strategies to be considered in a patient with PJI are:

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  Attempted eradication with implant retention and antibiotics (Debridement, antibiotics and implant retention: DAIR)

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  Attempted eradication with implant removal and antibiotics

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    With prosthesis replacement (in a 1-step or a 2-step exchange procedure).

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    Without prosthesis replacement (arthrodesis or resection arthroplasty).

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  Implant retention and long-term suppressive antibiotics (SAT), without attempted eradication.

The decision regarding the most appropriate medical and surgical strategy for a given patient should consider features of the prosthesis, the patient's baseline condition, his/her previous functional performance, life expectancy, desires and expectations, and also the surgical risk involved. Tsukayama's and Zimmerli's classifications of PJI are both helpful for guiding medical and surgical decisions in a given patient. These classifications are based on similar criteria, which take into account pathogenic aspects, the time of infection, and the diagnostic circumstances.

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  The best candidates for attempting eradication treatment with implant retention are those who:

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    have an early post-surgical (up to three months after the placement of the prosthesis) or hematogenous infection (A-II), with a stable implant, and surrounding skin and soft tissues in good condition.

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    have a short duration of symptoms (≤3 weeks) (B-II).

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    can be treated with rifampin (staphylococcal infections) or fluoroquinolones (infections caused by GNB) (A-II).

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  Some patients who do not strictly meet the above criteria may still benefit from this strategy, but its implementation should be considered on an individualized basis, since there is a higher likelihood of failure (B-II).

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  The prosthesis should be removed in cases of chronic PJI (A-II).

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  A 2-step exchange procedure is recommended in patients with chronic PJI (A-II).

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  In patients with acute PJI who are not candidates for eradication treatment with implant retention, a 2-step exchange procedure is recommended (B-II).

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  The performance of a 1-step exchange procedure may be considered in non-immunosuppressed patients if they have good bone stock, if the prosthetic surrounding soft tissues are in good condition, and if the infection is caused by microorganisms susceptible to antibiotics with good activity against sessile (biofilm-embedded) bacteria (B-II).

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  In patients with acute PJI in whom the removal of the prosthesis is not very complex, a 1-step exchange procedure is recommended as long as the causative microorganisms are susceptible to antibiotics with good activity against biofilm-embedded bacteria (C-III).

Suppressive antimicrobial therapy (SAT) is seen as an alternative strategy for cases of PJI in which the surgical treatment cannot be performed or will be insufficient for eradicating the infection. The following conditions need to be met for the indication of SAT:

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  Identification of the microorganism causing the infection.

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  Availability of oral antibiotics which are not toxic when administered over long periods of time. Possibility of a close follow-up of the patient.

In addition, it should be considered that pain due to looseness or implant instability will be not reverted by SAT.

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  Treatment with SAT may be considered in situations in which medical and surgical strategies are unlikely to cure the patient, and non-toxic long-term antimicrobials are available (B-II).

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  Treatment with SAT is not indicated in acute PJI managed early, with appropriate debridement and optimized antimicrobial therapy (E-II).

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  Surgical debridement must be performed promptly by an expert surgical team, with the patient in the best possible condition (C-III).

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  The surgical approach must be performed by open arthrotomy. Arthroscopy should only be considered in selected cases, and performed by expert surgeons (A-II).

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  The surgical debridement must be aggressive, methodical and exhaustive.

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    If feasible, the removable components of the prosthesis should be exchanged (B-II).

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    Copious irrigation (≥9L of saline) is recommended with no additives, performed by a low-pressure system (C-III).

See Table 1

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  For acute staphylococcal PJI managed with rifampin and levofloxacin, an 8-week schedule of treatment after debridement appears sufficient for most patients (B-I).

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  For PJI caused by other microorganisms treated with antibiotics with good activity against biofilm-embedded bacteria (i.e. ciprofloxacin for PJI caused by GNB), 8 weeks is also a reasonable duration (B-III).

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  In other clinical scenarios, the most appropriate duration of treatment remains uncertain. A variable period between 8 and 12 weeks may be adequate (B-III).

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  Monitoring of CRP during the follow-up is advisable; the persistence of high values is suggestive of treatment failure (B-III), but its total normalization must not be a condition for deciding the end of therapy (B-II).

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  During antimicrobial therapy, a close follow up of observance and potential adverse events of the treatment is recommended, performed by a clinician with expertise in antibiotics (C-III).

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  During the first 6 months after the end of a treatment aiming at eradication, patients must be followed up closely (B-III).

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  The frequency of follow-up visits may decrease afterwards. Follow-up should last at least one year (B-III).

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  Antibiotic-loaded spacers are recommended in the two-step exchange procedure (B-II).

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  The dose of local antibiotic ranges between 0.5 and 4g of vancomycin, and 0.25 and 4.8g of gentamycin or tobramycin (per every 40g of acrylic cement) (C-III).

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  The use of combined local antibiotics (vancomycin-gentamicin) is recommended until further evidence specifically addressing this topic is available (C-III).

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  In PJI caused by multi-drug resistant microorganisms, spacers may be still used as long as they are loaded with antibiotics active against these microorganisms (C-III).

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  In the two-step exchange procedure, an antibiotic-free period of 2–8 weeks and clinical stability before the second-step surgery is recommended (C-III).

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  The monitoring of ESR and/or CRP is recommended. The persistence of values above the normal range does not necessarily indicate the persistence of the infection, and sore-implantation should not be delayed (B-II). However, significant changes in these serum markers may imply the persistence of the infection or a superinfection (C-III).

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  Sampling of tissues and the cement spacer during the second-step surgery of a two-step exchange procedure is recommended in order to guarantee the sterility of the surgical site where the new prosthesis is to be placed (B-II).

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  Culture of the joint aspirate before the second-step surgery is not systematically recommended, although it may be of some use when the clinical and analytical evaluation of the patient suggests poor evolution, or in difficult-to-treat episodes caused by multi-drug resistant microorganisms or fungi (C-II).

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  Cultures of samples taken during the second-step surgery may be considered as positive if ≥1 or ≥2 of them yield a microorganism, depending on its pathogenicity (C-III).

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  Wide-spectrum antibiotic prophylaxis including nosocomial microorganisms that may potentially cause superinfection of the new prosthesis is recommended for the second-step surgery of a 2-step exchange procedure (C-III).

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  “Preemptive treatment” including microorganisms that could be isolated during the second-step surgery (usually multi-drug resistant SNC) is recommended: vancomycin (or another glycopeptide or lipopeptide) during the first 5 days after re-implantation or until confirmation that the samples taken during the second-step surgery yield no microorganisms (C-III).

Recommendations

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  Beginning an antimicrobial therapy 3–5 days prior to the 1-step exchange procedure is recommended if the etiological diagnosis has already been made, especially in infections caused by S. aureus or GNB (C-II).

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  Regardless of the decision regarding when to start antibiotics, an appropriate antimicrobial prophylaxis throughout the procedure must be guaranteed (A-I).

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  If no antimicrobial therapy has been initiated before the procedure, it should be delayed until the intraoperative sampling has been performed (C-III).

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  A minimum of 7 days of intravenous antibiotics with activity against the microorganisms causing the infection is recommended (dosage summarized in Table 1), followed by oral antibiotics for a total of 4–8 weeks (B-II).

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  If it has been decided to use a cemented prosthesis, a local antibiotic with activity against the microorganism causing the infection is recommended. If the etiology is unknown at the moment of the exchange procedure, the combination of vancomycin plus gentamycin is recommended (C-III).

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  In the case of PIOC (Tsukayama's classification) an antimicrobial treatment of 4–6 weeks is recommended. There is no need for further surgery. The same protocol is followed as in cases of PJI managed with a 1-step exchange procedure (B-III).

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  For cases in which the infected prosthesis is not to be replaced after its removal, the same antibiotics as those used for DAIR may be administered (see table) (B-II).

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  In these cases, the length of therapy may be shortened to 4 to 6 weeks (C-III).

  Implant retention and long-term suppressive antibiotics (SAT) without attempted eradication.

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  A surgical debridement before beginning SAT is recommended, if feasible (C-III).

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  Obtaining a valid sample for culture before starting SAT is particularly important (C-III).

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  For the choice of the specific antibiotic for SAT, the antimicrobial susceptibility of the microorganism causing the infection, the safety of the drug and the observance of the treatment must be considered. Except for the initial stages of SAT, these aspects must prevail over the optimization of the antimicrobial treatment (C-III).

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  Except for some particular cases, the use of combinations (and therefore the use of rifampin) is not recommended (D-III).

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  In cases undergoing surgical debridement, an initial intravenous treatment for at least 7 days is recommended. Nevertheless, prolonged intravenous treatment is not necessary when deciding on SAT management (C-III).

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  If it is necessary to stop or change the antibiotics due to the occurrence of adverse events, long periods without antibiotics are not recommended (D-III).

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  The prescription and control of a SAT must be performed by an expert in antimicrobial therapy, who will periodically follow up the clinical evolution of the infection and assess the possible occurrence of adverse events (B-III).

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  The use of linezolid is discouraged in SAT due to high risk of toxicity, which limits its prolonged administration (E-I).

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  The use of β-lactams, or low doses of co-trimoxazole, is recommended. Alternatively, other antimicrobials such as minocycline or clindamycin may be administered (C-III).