**Author details**

*Bacterial Biofilms*

**Resistance mechanisms**

Reduction in permeability

Drug and metal alteration

Drug and metal outflow

**Table 1.**

*Adapted from Baker-Austin et al. [66].*

(MIC) value up to four times higher than the others, suggesting a co-resistance

*Examples of characteristics and negative effects on metal and antibiotic resistance mechanisms.*

**Antibiotics References**

[32, 74]

[77, 78]

[79, 80]

Cip, Tet, Cholr, β-lactâmicos

As, Hg β-lactâmicos, Chlor [75, 76]

Tet, Chlor, β-lactâmicos

Trim, Rif

*Abbreviations: Cholr, chloramphenicol; Cip, ciprofloxacin; Rif, rifampicin; Tet, tetracycline; Trim, trimetropim.* 

Martins et al. [81] observed that isolates of *P. aeruginosa*, obtained from a contaminated river in southeastern Brazil, had a conjugative plasmid with coresistance to tetracycline and copper, reinforcing that resistance to antibiotics may be induced by selective pressure of heavy metals in the environment. Caille et al. [82] demonstrated that in *P. aeruginosa*, copper can induce imipenem resistance by the CopR-CopS two-component regulatory system mechanism. Ghosh et al. [83] verified resistance to ampicillin, arsenic, chromium, cadmium, and mercury in *Salmonella abortus equi* isolates and observed that after removal of the plasmids,

In order to corroborate the evidence of co-resistance of metals and antibiotics, some studies compared the resistance profiles of bacteria collected in contaminated and uncontaminated environments. Rasmussen and Sørensen [84] demonstrated an increase in the occurrence of conjugative plasmids at contaminated sites and found that the mercury and tetracycline resistance genes were located on the same plasmid. Mcarthur and Tuckfield [85] examined metal and antibiotic resistance profiles in contaminated and uncontaminated stream sediments and found that isolates obtained from the contaminated sediment were more resistant to kanamycin and

Thus, not only the indiscriminate use of antibiotics but also environmental contamination by heavy metals can pose risks and harm to human health, as resistance genes can be transferred horizontally from environmental microorganisms to

Increased urbanization and industrialization have contributed to heavy metal contamination in aquatic ecosystems, modifying the structure and function of microbial communities. The ability of microorganisms to survive under stress conditions, such as in the presence of heavy metals, depends on structural and biochemical attributes, as well as physiological and/or genetic adaptations. The studies cited demonstrated that the presence of heavy metals influences at different stages of biofilm formation. Additionally, the correlation between resistance to metals and antimicrobials was demonstrated, showing the environmental impact that these

mechanism for mercury and antimicrobials tested.

**Heavy metals**

As, Cu, Zn, Mn, Co, Ag

Cu, Co, Zn, Cd, Ni, As

Cell signaling change Hg, Zn, Cu Cip, β-lactâmicos,

isolates became sensitive to these compounds.

contaminants can cause in aquatic environments.

streptomycin than the others.

human diners [66].

**6. Conclusions**

**24**

Lívia Caroline Alexandre de Araújo1 and Maria Betânia Melo de Oliveira2 \*

1 Federal University of Pernambuco, Recife, Brazil

2 Department of Biochemistry of the Federal University of Pernambuco, Recife, Brazil

\*Address all correspondence to: mbetaniam2008@gmail.com

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
