Background and Aim: Dendrimers have antibacterial properties and can be used against microbial infections as alternative antibacterial agents with minimal side effects.  In this study we evaluated and compared nanostructure macromolecules called Poly (amidoamine) dendrimer generation 4 (PAMAM-G4) with conventional antibiotics in relation to resistance of isolated bacteria from water resources.

Materials and methods: 523 samples were collected from 108 water resources and membrane filter method was used for bacterial species isolation. Resistance of isolated species to amoxicillin, erythromycin, tetracycline and ciprofloxacin antibiotics was determined by measuring zones of inhibition and then compared to the resistance of these species to PAMAM-G4 dendrimer as an antibacterial agent. Also we measured maximum inhibitory concentration (MIC) of dendrimer against isolated bacteria.

Results: 7.4% of samples showed bacterial contamination. Frequency rates of isolated microbial species were as follows: Escherichia coli (28.2%), Proteus (12.8%), Klebsiella (17.9%), Enterobacter (15.3%), Pseudomonas (17.9%), Bacillus subtilis (5.1%) and Staphylococcus aureus (2.56%). Gram-negative species revealed high resistance to PAMAM-G4 dendrimer based on the measurement of zones of inhibition. PAMAM-G4 dendrimer didn't have any effect on inhibition of the growth of Enterobacter and Pseudomonas. MIC's against Escherichia coli, Klebsiella and Proteus were 1250, 500 and 1250 µg/ml respectively. Gram-positive species showed a good response to PAMAM-G4 dendrimer, so that the MIC's for Staphylococcus aureus and Bacillus subtilis were 1 and 2.5 µg/ml, respectively.

Conclusion: Because of increased number of resistant species to conventional antibiotics, PAMAM-G4 can be considered as a potent antibacterial agent against gram-positive bacteria.

Keywords: Poly amidoamine dendrimer, Antibiotic, Antibacterial agent, Drug resistance, Water resources.

Received: Dec 25, 2015      Accepted: Apr 6, 2016