Evaluation of the capacity and intensity of biofilm formation of Morganella morganii strains isolated from the community and the hospital in Londrina, Paraná, Brazil

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Morganella morganii is a Gram-negative enterobacterium that, despite belonging to normal intestinal microbiota and to the environment, is an opportunistic bacterium, especially in immunocompromised individuals, which can cause a broad spectrum of disease, especially when it accumulates virulence factors. An important virulence factor present in bacteria is the ability to form biofilms. Biofilms are structures formed by bacteria for their maintenance in hosts, protecting them against the action of the immune system and the action of antimicrobials, with their formation resulting from physical, chemical and biological events. Thus, this study sought to assess the capacity of biofilm formation and its intensity, from human infections of 68 hospital isolates and 70 community isolates of M. morganii, in the city of Londrina-PR, isolated from 2015 to 2020. For the biofilm assay, we used 96-well polystyrene plates, inoculated with sterile TSB and bacterial culture, being performed in quadruplicate. After 24 hours, the wells were subjected to washing, fixation and staining with crystal violet and later, reading in a spectrophotometer. The absorbance threshold value was the proof of biofilm formation and was defined as a sum of the arithmetic mean of the negative control and a triple value of its standard deviation (T=Xnc+3δ). The formed biofilms were classified in intensities as absent, weak, moderate strong or very strong. The results showed that of the 68 hospital isolates, 20 (29.41%) were classified as weak biofilm formers, 32 (47.05%) as moderate, 13 (19.12%) as strong and 3 (4.42 %) of very strong intensity, while of the 70 community isolates, 17 (24.29%) were classified as weak biofilm formers, 41 (58.57%) as moderate and 12 (17.14%) as strong. All isolates, regardless of the location of isolation, demonstrated the ability to form a biofilm. Hospital isolates showed a greater capacity to produce biofilms of very strong intensity when compared to community isolates. The isolates from the community showed a greater ability to produce moderate biofilm (OR:1.79 IR:0.91;3.53). The formation of biofilms in patients with urinary tract infections (UTI) can cause several problems, especially in patients who use catheters, as the material presents favorable conditions for the development of the biofilm structure. It is concluded that M. morganii isolates from human infections showed the ability to form biofilms, of different intensities, regardless of the source of isolation, favoring the infectious process, hindering the effectiveness of the treatment.

  • 1 Departamento de Microbiologia / Universidade Estadual de Londrina
  • 2 Departamento de Microbiologia / Centro de Ciências Biológicas / Universidade Estadual de Londrina
  • 3 UNIFIL / Centro Universitário Filadélfia
  • Microbiologia Médica Humana
Human Infection