The Brazilian Journal of Infectious Diseases The Brazilian Journal of Infectious Diseases
Braz J Infect Dis 2018;22:129-36 - Vol. 22 Num.2 DOI: 10.1016/j.bjid.2018.03.003
Original article
Biofilm production by clinical isolates of Pseudomonas aeruginosa and structural changes in LasR protein of isolates non biofilm-producing
Jailton Lobo da Costa Limaa,b,, , Lilian Rodrigues Alvesb, Paula Regina Luna de Araújo Jacoméb, João Pacífico Bezerra Netoc, Maria Amélia Vieira Macielb, Marcia Maria Camargo de Moraisa
a Universidade de Pernambuco (UPE), Instituto de Ciências Biológicas, Programa de Pós-graduação em Biologia Celular e Molecular Aplicada, Recife, PE, Brazil
b Universidade Federal de Pernambuco, Departamento de Medicina Tropical, Programa de Pós-Graduação em Medicina Tropical, Recife, PE, Brazil
c Universidade Federal de Pernambuco, Departamento de Genética, Recife, PE, Brazil
Received 28 January 2018, Accepted 13 March 2018
Abstract
Introduction

Biofilm production is an important mechanism for the survival of Pseudomonas aeruginosa and its relationship with antimicrobial resistance represents a challenge for patient therapeutics. P. aeruginosa is an opportunistic pathogen frequently associated to nosocomial infections, especially in imunocompromised hosts.

Objectives

Analyze the phenotypic biofilm production in P. aeruginosa isolates, describe clonal profiles, and analyze quorum sensing (QS) genes and the occurrence of mutations in the LasR protein of non-biofilm producing isolates.

Methods

Isolates were tested for biofilm production by measuring cells adherence to the microtiter plates. Clonal profile analysis was carried out through ERIC-PCR, QS genes were by specific PCR.

Results

The results showed that 77.5% of the isolates were considered biofilm producers. The results of genotyping showed 38 distinct genetic profiles. As for the occurrence of the genes, 100% of the isolates presented the lasR, rhlI and rhlR genes, and 97.5%, presented the lasI gene. In this study nine isolates were not biofilm producers. However, all presented the QS genes. Amplicons related to genes were sequenced in three of the nine non-biofilm-producing isolates (all presenting different genetic similarity profile) and aligned to the sequences of those genes in P. aeruginosa strain PAO1 (standard biofilm-producing strain). Alignment analysis showed an insertion of three nucleotides (T, C and G) causing the addition of an amino acid valine in the sequence of the LasR protein, in position 53.

Conclusion

The modeling of the resulting LasR protein showed a conformational change in its structure, suggesting that this might be the reason why these isolates are unable to produce biofilm.

Keywords
Pseudomonas aeruginosa, Biofilm, Multiresistance, Quorum sensing (QS)
Braz J Infect Dis 2018;22:129-36 - Vol. 22 Num.2 DOI: 10.1016/j.bjid.2018.03.003