The increasing clinical incidence and host risk of biomaterial-centered infections, as well as the reduced effectiveness of clinically relevant antibiotics to treat such infections, provide compelling reasons to develop new approaches for treating implanted biomaterials in a surgical context. We describe the direct local delivery of polyclonal human antibodies to abdominal surgical implant sites to reduce infection severity and mortality in a lethal murine model of surgical implant-centered peritoneal infection. Surgical implant-centered peritonitis was produced in 180 female CF-1 mice by the direct inoculation of surgical-grade polypropylene mesh disks placed in the peritoneal cavity with lethal doses of either methicillin-resistant Staphylococcus aureus (MRSA) or Pseudomonas aeruginosa. Mice randomly received a resorbable antibody delivery vehicle at the implant site: either a blank carboxymethylcellulose (CMC) aqueous gel or the same CMC gel containing 10 mg of pooled polyclonal human immunoglobulin G locally on the implant after infection, either alone or in combination with systemic doses of cefazolin or vancomycin antibiotics. Human antibodies were rapidly released (first-order kinetics) from the gel carrier to both peritoneal fluids and serum in both infection scenarios. Inocula required for lethal infection were substantially reduced by surgery and the presence of the implant versus a closed lethal peritonitis model. Survival to 10 days with two different gram-negative P. aeruginosa strains was significantly enhanced (p < 0.01) by the direct application of CMC gel containing antibodies alone to the surgical implant site. Human-equivalent doses of systemic vancomycin provided a significantly improved benefit (p < 0.01) against lethal, implant-centered, gram-positive MRSA infection. However, locally delivered polyclonal human antibodies in combination with a range of systemic vancomycin doses against MRSA failed to improve host survival. Successful antibody therapy against gram-negative, implant-centered infections complements the clinically routine use of systemic antibiotics, providing a mechanism of protection independent of antibiotic resistance.

Escherichia coli biofilms on two polyethylene disks were implanted subcutaneously into rabbits receiving systemic gentamicin. Ultrasound was applied for 24 h to one disk. Both disks were removed, and viable bacteria were counted. Pulsed ultrasound significantly reduced bacterial viability below that of nontreated biofilms without damage to the skin.

Biofilm infections are a common complication of prosthetic devices in humans. Previous in vitro research has determined that low-frequency ultrasound combined with aminoglycoside antibiotics is an effective method of killing biofilms. We report the development of an in vivo model to determine if ultrasound enhances antibiotic action. Two 24-h-old Escherichia coli (ATCC 10798) biofilms grown on polyethylene disks were implanted subcutaneously on the backs of New Zealand White female rabbits, one on each side of the spine. Low-frequency (28.48-kHz) and low-power-density (100- and 300-mW/cm2) continuous ultrasound treatment was applied for 24 h with and without systemic administration of gentamicin. The disks were then removed, and the number of viable bacteria on each disk was determined. At the low ultrasonic power used in this study, exposure to ultrasound only (no gentamicin) caused no significant difference in bacterial viability. In the presence of antibiotic, there was a significant reduction due to 300-mW/cm2 ultrasound (P = 0.0485) but no significant reduction due to 100-mW/cm2 ultrasound. Tissue damage to the skin was noted at the 300-mW/cm2 treatment level. Further development of this technique has promise in treatment of clinical implant infections.

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The effect of erythromycin on planktonic cultures of Pseudomonas aeruginosa, with and without application of 70 kHz ultrasound, was studied. Ultrasound was applied at levels that had no inhibitory effect on cultures of Ps. aeruginosa. Ultrasound in combination with erythromycin reduced the viability of Ps. aeruginosa by 1–2 orders of magnitude compared with antibiotic alone, even at concentrations below the minimum inhibitory concentration (MIC). Electron‐spin resonance studies suggest that ultrasound induces uptake of antibiotic by perturbing or stressing the membrane. This application of ultrasound may be useful for expanding the number of drugs available for treating localized infections by rendering bacteria susceptible to normally ineffective antibiotics.

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WA letter to the editor addressing recent concerns about the necessity of microbiology as a prerequisite for pre-nursing and pre-allied health programs.

Author Steve Steubner explores the micobes native to the state of Idaho and their impact on the environment, citizens, and businesses of the state. An excellent resource for K-12 teachers, introductory biology and microbiology instructors, microbe enthusiasts, and denizens of the Pacific Northwest alike. Review of: Idaho Microbes: How Tiny Single-Celled Organisms Can Harm, or Save, our World. Steve Stuebner with Todd Shallat; (2015). Boise State University Press, Boise, ID. 168 pages.