Antibacterial activity of iron oxide, iron nitride, and tobramycin conjugated nanoparticles against Pseudomonas aeruginosa biofilms

Table 4 Susceptibility of P. aeruginosa colonies beneath mucin, alginate, or alginate and mucin barriers, determined by disk diffusion

Disk no./compound	Mucin	Alginate	Alginate + Mucin
1. Fe₃O₄ NPs† 10 μg	14/I	0/R	22/S
2. Fe₃O₄@ALG:TOBRA 10 μg	0/R	0/R	0/R
3. Tobramycin 10 μg	0/R	0/R	0/R
4. Tobramycin 100 μg**	11/R**	14/R**	5/R**
5. Tobramycin 200 mg**	30/R**	35/R**	30/R**

Disk diffusion method was used. Minimum concentrations demonstrating susceptibility in previous disk diffusion studies were used for NPs and NP-tobramycin conjugates. ^†Uncapped NPs, ALG: alginate, TOBRA: tobramycin
* Maximum CLSI cutoff concentration for susceptibility of tobramycin 10 μg absorbed onto disk
** Corresponding to experimentally determined susceptibility, these doses of tobramycin shown were up to five orders of magnitude higher than the CLSI standard dose for disk diffusion. Therefore, although inhibition was observed, these colonies were tobramycin resistant by CLSI standard

ISSN: 1477-3155