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Volume 2017 (2017), Article ID 2960194, 7 pages
https://doi.org/10.1155/2017/2960194
Research Article

SEM Analysis of Surface Impact on Biofilm Antibiotic Treatment

LEPABE, Department of Chemical Engineering, Faculty of Engineering, University of Porto, Porto, Portugal

Correspondence should be addressed to Filipe José Mergulhão

Received 30 July 2016; Revised 17 October 2016; Accepted 7 November 2016; Published 11 January 2017

Academic Editor: Daniele Passeri

Copyright © 2017 Luciana Calheiros Gomes and Filipe José Mergulhão. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The aim of this work was to use scanning electron microscopy (SEM) to investigate the effect of ampicillin treatment on Escherichia coli biofilms formed on two surface materials with different properties, silicone (SIL) and glass (GLA). Epifluorescence microscopy (EM) was initially used to assess biofilm formation and killing efficiency on both surfaces. This technique showed that higher bacterial colonization was obtained in the hydrophobic SIL than in the hydrophilic GLA. It has also shown that higher biofilm inactivation was attained for GLA after the antibiotic treatment (7-log reduction versus 1-log reduction for SIL). Due to its high resolution and magnification, SEM enabled a more detailed analysis of the antibiotic effect on biofilm cells, complementing the killing efficiency information obtained by EM. SEM micrographs revealed that ampicillin-treated cells have an elongated form when compared to untreated cells. Additionally, it has shown that different materials induced different levels of elongation on cells exposed to antibiotic. Biofilms formed on GLA showed a 37% higher elongation than those formed on SIL. Importantly, cell elongation was related to viability since ampicillin had a higher bactericidal effect on GLA-formed biofilms. These findings raise the possibility of using SEM for understanding the efficacy of antimicrobial treatments by observation of biofilm morphology.