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oai:repisalud.isciii.es:20.500.12105/227132024-11-29T02:53:26Zcom_20.500.12105_15322com_20.500.12105_2051col_20.500.12105_16967

00925njm 22002777a 4500 dc Rojo Molinero, Estrella author Maciá, Maria Dolores author Oliver, Antonio author 2019-03-22 The complex spatial structure and the heterogeneity within biofilms lead to the emergence of specific social behaviors. However, the impact of resistant mutants within bacterial communities is still mostly unknown. Thus, we determined whether antibiotic resistant mutants display selfish or altruistic behaviors in mixed Pseudomonas aeruginosa biofilms exposed to antibiotics. ECFP-tagged P. aeruginosa strain PAO1 and its EYFP-tagged derivatives hyperproducing the beta-lactamase AmpC or the efflux pump MexAB-OprM were used to develop single or mixed biofilms. Mature biofilms were challenged with different concentrations of beta-lactams to monitor biofilm structural dynamics, using confocal laser scanning microscopy (CLSM), and population dynamics, through enumeration of viable cells. While exposure of single wild-type PAO1 biofilms to beta-lactams lead to a major reduction in bacterial load, it had little effect on biofilms formed by the resistant mutants. However, the most reveling finding was that bacterial load of wild-type PAO1 was significantly increased when growing in mixed biofilms compared to single biofilms. In agreement with CFU enumeration data, CLSM images revealed the amplification of the resistant mutants and their protection of susceptible populations. These findings show that mutants expressing diverse resistance mechanisms, including beta-lactamases, but also, as evidenced for the first time, efflux pumps, protect the whole biofilm community, preserving susceptible populations from the effect of antibiotics. Thus, these results are a step forward to understanding antibiotic resistance dynamics in biofilms, as well as the population biology of bacterial pathogens in chronic infections, where the coexistence of susceptible and resistant variants is a hallmark. Rojo Molinero E, Macia Romero MD, Oliver A. Social Behavior of Antibiotic Resistant Mutants Within Pseudomonas aeruginosa Biofilm Communities. Front Microbiol. 2019 Mar 22;10:570. 10.3389/fmicb.2019.00570 1664-302X Frontiers in Microbiology http://hdl.handle.net/20.500.13003/17580 30967851 L627958297 2-s2.0-85066618061 https://hdl.handle.net/20.500.12105/22713 461984800001 Pseudomonas aeruginosa Biofilms Bacterial communities Resistance mutants Beta-lactam antibiotics Antibiotic resistance Social Behavior of Antibiotic Resistant Mutants Within Pseudomonas aeruginosa Biofilm Communities