Teicoplanin-based antimicrobial therapy in Staphylococcus aureus bone and joint infection: tolerance, efficacy and experience with subcutaneous administration

Although teicoplanin is among the drugs of choice for the treatment of staphylococcal BJI, efficacy, safety and pharmacokinetics data in that specific setting are scarce. Thus, the present study provides relevant features with regards to staphylococcal BJI management. Our study is subjected to limitations BJI studies generally encounter such as the retrospective design coupled to the inherent lack of control patients. The limited patients’ recruitment, the variety of infection types, surgical management and medical treatment approaches also constitute a limitation to generalisation.

These current difficulties in the field of BJI explain the limited and controversial data available on the efficacy of teicoplanin in staphylococcal BJI. In past studies, treatment success rate ranged from 53 to 91 % [11‐14]. The low success rate observed in our study (60 %) may be explained by several factors. First, there is a significant selection bias as patients were recruited in a reference center dedicated to manage complex BJI with a high-risk of failure. In addition, most of past studies included native BJI with a relatively short follow-up (<1 year). Finally, pharmacodynamics parameters may impact the outcome [15, 16]. In our study, a C_min reaching the therapeutic target of 15 mg/L was achieved in a quarter of cases at the first measurement (day 3 to 5) and in two thirds of patients within 2 weeks of treatment. The use of higher doses may improve these pharmacological parameters. In the study by LeFrock et al, the teicoplanin C_min averaged 10 mg/L after 6 days in patients receiving 6 mg/kg/day after 5 loading doses of 6 mg/kg/12 h compared to 20 mg/L from the third day in patients receiving 12 mg/kg/day after 5 loading doses of 12 mg/kg/12 h [12]. If no difference was observed regarding osteomyelitis outcome, higher doses were associated with a better outcome among patients with native septic arthritis. Nevertheless, clinical outcome according to C_min was not an intended end-point in the study. Greenberg et al reported a favorable outcome in patients with a C_min > 30 mg/L, but with no comparative data [17]. It is our belief that the loading dose should be increased to 8 mg/kg/12 h to optimize trough concentrations, particularly in case when orthopedic implant is retained. Other determinants of therapeutic success had already been described, such as inflammatory systemic disease, diabetes and abscess [18, 19]. Conversely, our study was not associated with MRSA as a negative prognostic factor as found elsewhere [20]. This last prognostic factor probably relies on the benefit of receiving anti-staphylococcal penicillins for a MSSA compared to glycopeptides [21, 22], which could not be highlighted in our series as all patients received teicoplanin, including those with MSSA infection. Finally, although all S. aureus isolates included in our study were tested susceptible to teicoplanin [23], the exact MIC of each isolate was not available and could consequently not be challenged as an outcome predictor. As described with vancomycin, high teicoplanin MICs (i.e., > 1.5 mg/L) have been associated with unfavorable outcome and higher mortality rate among teicoplanin-treated MRSA bacteremia [24].

Regarding safety data, our results highlighted an excellent tolerance of teicoplanin with a 10 % incidence of AE, which is consistent with the toxicity rate of 9 to 18 % observed in other similar studies [11, 13, 25]. However, the incidence of AE was probably been underestimated due to the retrospective nature of our study (memory bias for non-severe AE). Indeed, in the prospective study of LeFrock et al, the rate of AE was 35 %, requiring discontinuation of treatment in 17 % of the cases [12]. Very few data support enhanced AE related to teicoplanin dose increase [26]. LeFrock et al reported fever in 5.6 and 13.1 % of patients receiving 6 and 12 mg/kg/day of teicoplanin, respectively, with similar data regarding cutaneous rashes (7.6 and 15.4 %, respectively) [12]. In our study, teicoplanin daily dose and overexposure within 2 weeks of treatment were not predictors of AE. In two other studies, a dose increase from 400 to 600 mg/day was not associated with an increased risk of toxicity [27, 28].

The description of subcutaneous administration of teicoplanin is another important highlight of our study, showing similar efficacy, safety and pharmacokinetics characteristics compared to IV administration. The retrospective design may result in underestimating non-serious AE such as injection site reactions. In a recent prospective evaluation of SC teicoplanin in 30 patients, 90 % of patients presented moderate local AE (grades 1–2) and no severe local reaction (grade ≥3) [29]. Of note, none of our patients had SC teicoplanin infusion exceeding 600 mg, reported as an independent risk factor for local reaction in the study by El Samad et al [29]. Subcutaneous teicoplanin may be particularly useful in patients with BJI eligible for OPAT achieving efficacy and allowing cost reduction [30, 31]. Some authors have even proposed a 3-injections weekly regimen with a satisfactory success rate and an estimated saving of $60,000 per episode of BJI [32, 33]. However, a study has tempered this suggestion by showing a non-significant trend toward a higher risk of failure in patients treated by teicoplanin for BJI [34]. Further studies, optimally with a prospective and controlled design, are warranted to assess both the risk-benefit as well as the cost-benefit of teicoplanin in staphylococcal BJI.