Colistin-containing cement spacer for treatment of experimental carbapenemase-producing Klebsiella pneumoniae prosthetic joint infection

[Bone cement as a local antibiotic carrier]

BACKGROUND

There is widespread consensus that adjuvant local use of antimicrobial agents in combination with their systemic administration can better prevent and treat implant-associated musculoskeletal infections. The advantage of local antibiotics lies in their particular pharmacokinetics with initially high antibiotic concentrations at the implant site with only low systemic uptake.

AIM OF TREATMENT

The aim of local application is to protect the foreign bodies directly at the implantation site from bacterial colonization and biofilm formation (prophylaxis) and to support the eradication of an already established infection after surgical debridement (treatment). Since the observations of Prof. Buchholz, bone cement has been the most frequently used local carrier system.

APPLICATION

In cases of infection, surgeons should ideally work together with microbiologists, infectiologists or clinical pharmacists to determine which anti-infective agents are indicated systemically for the patient and which ones are indicated locally with PMMA cement, based on the pathogen(s) and antibiograms. However, for the anti-infective agents administered with bone cement, there is still uncertainty about which agents can be added to this carrier material and at what concentrations. Accordingly, the authors of this review article not only summarize the rationale and evidence for local antibiotic use but also elaborate on the points that must be considered for admixing these agents to the cement.

Efficacy of generic meropenem products in combination with colistin in carbapenemase-producing Klebsiella pneumoniae experimental osteomyelitis

Guidelines for the management of carbapenemase-producing Enterobacterales (CPE) infections recommend a combination of two active agents, including meropenem if the minimum inhibitory concentration (MIC) is ≤8 mg/L. The therapeutic equivalence of meropenem generics has been challenged. We compared the bactericidal activity of meropenem innovator (AstraZeneca) and four generic products (Actavis, Kabi, Mylan and Panpharma), both in vitro and in vivo, in association with colistin. In vitro time-kill studies were performed at 4 × MIC. An experimental model of KPC-producing Klebsiella pneumoniae osteomyelitis was induced in rabbits by tibial injection of a sclerosing agent followed by 2 × 10⁸ CFU of K. pneumoniae KPC-99YC (meropenem MIC = 4 mg/L; colistin MIC = 1 mg/L). At 14 days after inoculation, treatment for 7 days started in seven groups of ≥10 rabbits, including a control group, a colistin group, and one group for each meropenem product (i.e. the innovator and four generics), in combination with colistin. In vitro, meropenem + colistin was bactericidal with no viable bacteria after 6 h, and this effect was similar with all meropenem products. In the osteomyelitis model, there was no significant difference between meropenem generics and the innovator when combined with colistin. Colistin-resistant strains were detected after treatment with colistin + meropenem innovator (n = 3) and generics (n = 3). The efficacy of four meropenem generics did not differ from the innovator in vitro and in an experimental rabbit model of KPC-producing K. pneumoniae osteomyelitis in terms of bactericidal activity and the emergence of resistance.