Biofilm prevention of gram-negative bacterial pathogens involved in periprosthetic infection by antibiotic-loaded calcium sulfate beads in vitro

Abstract

Biofilm formation represents a key stage in the pathogenesis of prosthetic infections (PIs). More tolerant to antibiotics than their planktonic counterparts, biofilm bacteria are difficult to eradicate using conventional therapeutic regimes. A common approach in PI management is the adjunctive use of localised antibiotics in addition to systemic administration in an attempt to protect the implant from colonisation by infiltrating bacteria. This study evaluates the antibacterial and antibiofilm efficacy of antibiotic-loaded dissolvable calcium sulphate, previously shown to be effective against key gram-positive pathogens, against gram-negative species important in the establishment of chronic infection in PIs. Synthetic calcium sulfate beads loaded with tobramycin, vancomycin and both antibiotics in combination were assessed for their ability to eradicate planktonic Acinetobacter baumannii, Pseudomonas aeruginosa and Klebsiella pneumoniae strains. The efficacy of the beads in preventing biofilm formation and eliminating established biofilms over multiple days was evaluated using confocal laser scanning microscopy (CSLM) imaging combined with image analysis and viable cell counts. Beads loaded with antibiotics demonstrated effective eluting concentrations for up to 37 d depending on the bacterial strain. In the presence of repeated bacterial challenges, antibiotic-loaded beads prevented bacterial colonisation and significantly reduce biofilm formation for the duration of the assay (7 d). Complete eradication of established biofilms was more difficult with evidence of biofilm regrowth after 1 week of contact with antibiotic-loaded beads, despite data suggesting a complete kill was achieved at earlier timepoints of 24 h and 72 h in the case of K. pneumoniae and P. aeruginosa. This study provides further evidence that calcium sulfate beads loaded with vancomycin and tobramycin may be a useful adjunctive component to the successful management of PIs.

A dual PMMA/calcium sulfate carrier of vancomycin is more effective than PMMA‐vancomycin at inhibiting Staphylococcus aureus growth in vitro

“…In this work, compared with the PMMA‐v, the dual carrier‐v can optimize the vancomycin release, especially in the early stages of drug release experiments. Calcium sulfate‐based antibiotic carriers have presented its antibiofilm formation because of its long‐lasting antibacterial capacity [31]. More importantly, the dual carrier‐v can yield synergistic roles.…”

Antibiotic loaded calcium sulfate bead and pulse lavage eradicates biofilms on metal implant materials in vitro

“…Another concern associated with localized antibiotic therapy is that of the development of antibiotic resistance if the infecting bacteria are exposed to sub‐MIC concentrations for prolonged periods. In vitro data shows that when bacteria are in biofilms often, depending upon the strain, much higher concentrations of antibiotics are required to achieve clinically relevant reductions than can be achieved systemically, thus localized delivery via impregnated bone cements is a mechanism commonly used by surgeons to increase the antibiotic concentration at the site of infection. A concern with any diffusion based release in which the reservoir is not replenished is that the concentration will inevitably fall below the MIC as a function of time and distance from the reservoir.…”

“…Mineral beads such as CS‐B do not play a structural role but have the advantage that they completely dissolve when implanted in soft tissues releasing all antibiotic and thus also negate need for subsequent removal and their small size can be conducive to obtaining high packing density in terms of dead space management in the vicinity of the prosthesis . Previously we have assessed CS‐B loaded with vancomycin hydrochloride (VAN) and tobramycin sulfate (TOB) to prevent or kill biofilms from various Gram positive and negative biofilm forming PJI pathogens using a polystyrene culture dish as a substrate . Here we extend our study to biofilms grown on 316L stainless steel (SS) as a representative orthopaedic metal and compare the efficacy of eradicating P. aeruginosa and S. aureus biofilms using PL alone, CS‐B loaded with VAN and TOB alone and the two treatments (PL and CS‐B) in combination.…”

Careful interpretation of the wound status is needed with use of antibiotic impregnated biodegradable synthetic pure calcium sulfate beads: Series of 39 cases

“…A biodegradable alternative to PMMA is calcium sulfate, which has long been reported as an effective means of delivering antibiotic 8 - 10 . Its biodegradable nature eliminates the need for subsequent surgical removal, and recent studies have indicated it may be effective tool in preventing the formation of bacterial biofilms 11 , 12 . Calcium sulfate also has the advantage of providing an effective osteoconductive scaffold 13 , supporting new bone growth when implanted in a bone void 14 .…”