Targeting intracellularStaphylococcus aureusto lower recurrence of orthopaedic infection

Abstract

Staphylococcus aureus is often found in orthopaedic infections and may be protected from commonly prescribed antibiotics by forming biofilms or growing intracellularly within osteoblasts. To investigate the effect of non-antibiotic compounds in conjunction with antibiotics to clear intracellular and biofilm forming S. aureus causing osteomyelitis. SAOS-2 osteoblast-like cell lines were infected with S. aureus BB1279. Antibiotics (vancomycin, VAN; and dicloxacillin, DICLOX), bacterial efflux pump inhibitors (piperine, PIP; carbonyl cyanide m-chlorophenyl hydrazone, CCCP), and bone morphogenetic protein (BMP-2) were evaluated individually and in combination to kill intracellular bacteria. We present direct evidence that after gentamicin killed extracellular planktonic bacteria and antibiotics had been stopped, seeding from the infected osteoblasts grew as biofilms. VAN was ineffective in treating the intracellular bacteria even at 10× MIC; however in presence of PIP or CCCP the intracellular S. aureus was significantly reduced. Bacterial efflux pump inhibitors (PIP and CCCP) were effective in enhancing permeability of antibiotics within the osteoblasts and facilitated killing of intracellular S. aureus. Confocal laser scanning microscopy (CLSM) showed increased uptake of propidium iodide within osteoblasts in presence of PIP and CCCP. BMP-2 had no effect on growth of S. aureus either alone or in combination with antibiotics. Combined application of antibiotics and natural agents could help in the treatment of osteoblast infected intracellular bacteria and biofilms associated with osteomyelitis. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1086-1092, 2018.

Hybrid Antimicrobial Peptide Targeting Staphylococcus aureus and Displaying Anti-infective Activity in a Murine Model

“…Subcutaneous infections are the most common form of S. aureus, causing approximately 70% of osteomyelitis and 80% of joint infections in patients with rheumatoid arthritis and several other bone diseases (Dusane et al, 2018). In our study, S2 significantly reduced bacterial counts and dermatocyst size, which was similar to the effect of vancomycin.…”

Locally delivered adjuvant biofilm‐penetrating antibiotics rescue impaired endochondral fracture healing caused by MRSA infection

“…First, it is recognized that rifampin should not be used as systemic monotherapy due to the development of antibiotic resistance 29,30 . We chose to use rifampin due to its ability to penetrate bacterial cell membranes and biofilms and efficacy against MRSA and sought to evaluate its value as an adjunctive agent to standard antibiotic practices in the prevention and treatment of musculoskeletal infection 29,30 . Other rifampin‐only local delivery methods—mesh and powders—have been studied in the context of local infection prevention strategies 31,32 .…”

“…Intracellular infection and biofilm formation are major mechanisms by which Staphylococcal infections become established (Figure 1). 27,28 Unlike vancomycin, which is typically used to treat MRSA infection, rifampin is effective against biofilms and can target intracellular Staphylococcus 29,30 . Although systemic rifampin is not administered alone out of concern for antibiotic resistance, it has been used as a single‐agent local antibiotic for several applications delivered in the form of solutions, powders, and mesh coatings 31–33 …”

Local Bacteriophage Delivery for Treatment and Prevention of Bacterial Infections

“…A 3log 10 CFU reduction of intracellular Salmonella was observed for the HAP-phage complex while standalone phage caused no significant reduction of intracellular CFU ( Fulgione et al, 2019 ). As part of the pathology of bone infection, S. aureus bacteria are also known to reside intracellularly where antimicrobial treatments might be less effective ( Dusane et al, 2018 ). While Salmonella osteomyelitis is relatively rare, this intracellular phage delivery system could present a promising tool to target intracellular S. aureus bacteria.…”