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Abstract Otitis media (OM), known as a middle ear infection, is the leading cause of antibiotic prescriptions for children. With wide-spread use of antibiotics in OM, resistance to antibiotics continues to decrease the efficacy of the treatment. Furthermore, as the presence of a middle ear biofilm has contributed to this reduced susceptibility to antimicrobials, effective interventions are necessary. A miniaturized 3D-printed microplasma jet array has been developed to inactivatePseudomonas aeruginosa, a common bacterial strain associated with OM. The experiments demonstrate the disruption of planktonic and biofilmP. aeruginosaby long-lived molecular species generated by microplasma, as well as the synergy of combining microplasma treatment with antibiotic therapy. In addition, a middle ear phantom model was developed with an excised rat eardrum to investigate the antimicrobial effects of microplasma on bacteria located behind the eardrum, as in a patient-relevant setup. These results suggest the potential for microplasma as a new treatment paradigm for OM. 

Disinfectant decay by biofilms in distribution networks during stagnation can allow opportunistic pathogens' transmission and thus compromise drinking water safety. Applying phosphate-based corrosion inhibitors to the system can exacerbate disinfectant decay by providing nutrients to biofilms growing inside premise plumbings. In this study, we evaluate the impacts of corrosion inhibitors on biofilms' structural and chemical properties that form in premise plumbing, and the resulting implications for disinfectant decay. Two commonly used phosphate-based (phosphate blends and phosphate) corrosion inhibitors were added separately to simulated drinking water for biofilm development over 1 to 2 years. Optical coherence tomography (OCT) imaging showed that the studied biofilms' thickness, porosity, and porous structure did not change after exposure to free chlorine for 24 h or monochloramine for 120 h. Compared with groundwater biofilms, phosphate-based biofilms had the highest overall porosity due to their many connecting channels. The phosphate-based biofilms consumed free chlorine or monochloramine at a faster rate than groundwater biofilms. Experimental results showed that phosphate-based biofilms consumed more monochloramine after 96 h of contact than other biofilms. A separate set of experiments involving disinfectant decay with suspended biomass material, together with the OCT results, provided parameters for a simplified quasi-first-order reaction–diffusion model so that predictive modeling of decay in biofilms under stagnation conditions could be attempted without parameter fitting. The biofilm modeling results provided a close estimate for free chlorine decay while underestimating monochloramine decay. In agreement with the experimental results, the model results indicate that the phosphate-based biofilms led to slightly faster free chlorine consumption and monochloramine consumption than groundwater biofilms and indicate that diffusion limitation imposed by biofilm pore structure on disinfectant decay is important. The study results suggest that using phosphate-based corrosion inhibitors may lead to a rapid depletion of residual disinfectant during stagnation in the presence of biofilms.