Table 2

Antimicrobial effect of nanoparticles on ampicillin-resistant and ampicillin-susceptible bacteria

NanoparticleaStrain testedbMean log10 CFU of bacteria recovered posttreatment/ml ± SEM at various nanoparticle concnsc
AuNP-AMP (μg/ml)20.04.02.01.00.20Control
E. coli K-12(pAMP) (R)<1<1<1<18.22 ± 0.058.25 ± 0.07
E. coli K-12 (S)<1<1<1<17.19 ± 0.067.43 ± 0.09
E. coli O157:H7 (S)<1<1<1<18.57 ± 0.029.04 ± 0.04
E. coli O91:H21 (S)<1<1<14.64 ± 0.048.98 ± 0.059.00 ± 0.04
V. cholera (S)<1<1<19.33 ± 0.029.37 ± 0.039.39 ± 0.02
P. aeruginosa (R)<1<19.41 ± 0.039.63 ± 0.059.68 ± 0.069.64 ± 0.03
E. aerogenes (R)<1<15.36 ± 0.067.48 ± 0.089.56 ± 0.019.56 ± 0.01
S. aureus (MRSA) (R)<1<14.86 ± 0.158.62 ± 0.038.71 ± 0.068.93 ± 0.13
AgNP (μg/ml)20.04.02.0NDNDControl
E. coli K-12(pAMP)<1<19.52 ± 0.029.65 ± 0.03
E. coli K-12<1<19.10 ± 0.049.12 ± 0.03
E. coli O157:H7<1<19.57 ± 0.039.54 ± 0.03
E. coli O91:H21<1<19.23 ± 0.049.32 ± 0.02
V. cholerae<19.23 ± 0.039.28 ± 0.039.19 ± 0.03
P. aeruginosa<1<19.66 ± 0.059.72 ± 0.05
E. aerogenes<1<19.53 ± 0.019.53 ± 0.04
S. aureus (MRSA)<1<19.41 ± 0.109.20 ± 0.05
AgNP-AMP (μg/ml)20.04.02.01.00.20Control
E. coli K-12(pAMP)<1<1<1<18.17 ± 0.058.12 ± 0.08
E. coli K-12<1<1<1<18.67 ± 0.048.30 ± 0.06
E. coli O157:H7<1<1<1<19.25 ± 0.029.35 ± 0.01
E. coli O91:H21<1<1<1<19.47 ± 0.039.58 ± 0.02
V. cholerae<1<1<19.19 ± 0.049.21 ± 0.039.23 ± 0.04
P. aeruginosa<1<1<1<19.63 ± 0.039.55 ± 0.03
E. aerogenes<1<15.36 ± 0.067.48 ± 0.089.57 ± 0.019.56 ± 0.01
S. aureus (MRSA)<1<14.64 ± 0.148.67 ± 0.058.78 ± 0.059.06 ± 0.13
  • a AuNP-AMP and AgNP-AMP represent gold and silver nanoparticles functionalized with ampicillin; respectively; AgNP represents silver nanoparticles. Nanoparticles were used at 20.0, 4.0, 2.0, 1, and 0.2 μg/ml.

  • b (R), ampicillin resistant; (S), ampicillin sensitive; pAMP, pPCR-Script Amp SK+.

  • c Experiments were performed in triplicate. Three independent studies were performed for AgNP was three, and five independent studies were performed for AgNP-AMP and AuNP-AMP. The results shown are representative of tests for each condition. CFU log10 values in boldface are statistically significant (P < 0.005 [two-tailed Student t test]). Values listed as “<1” mean that all bacteria were killed after treatment with nanoparticles. ND, not done.