Biofilm production by multiresistant Corynebacterium striatum associated with nosocomial outbreak

Abstract

Corynebacterium striatum is a potentially pathogenic microorganism that causes nosocomial outbreaks. However, little is known about its virulence factors that may contribute to healthcare-associated infections (HAIs). We investigated the biofilm production on abiotic surfaces of multidrug-resistant (MDR) and multidrug-susceptible (MDS) strains of C. striatum of pulsed-field gel electrophoresis types I-MDR, II-MDR, III-MDS and IV-MDS isolated during a nosocomial outbreak in Rio de Janeiro, Brazil. The results showed that C. striatum was able to adhere to hydrophilic and hydrophobic abiotic surfaces. The C. striatum 1987/I-MDR strain, predominantly isolated from patients undergoing endotracheal intubation procedures, showed the greatest ability to adhere to all surfaces. C. striatum bound fibrinogen to its surface, which contributed to biofilm formation. Scanning electron microscopy showed the production of mature biofilms on polyurethane catheters by all pulsotypes. In conclusion, biofilm production may contribute to the establishment of HAIs caused by C. striatum.

Fig. 1:. Corynebacterium striatum adherence to glass surfaces (24 h incubation) evaluated by quantitative and semiquantitative tests. In detail, glass tubes with 1987/I strain exhibiting confluent coat of sessile forms on the surface of glass tube wall and with negative control (trypticase soy broth medium without bacteria). CFU: colony-forming unit.

Fig. 2:. Corynebacterium striatum adherence to polyurethane surfaces evaluated by quantitative and semiquantitative tests. In detail, 1987/I strain infected catheter segment cultured on blood agar plates (roll plate technique). CFU: colony-forming unit.

Fig. 3:. scanning electron micrographs illustrating biofilm formation on polyurethane catheter surfaces after 24 h incubation with different Corynebacterium striatum strains. Pulsed-field gel electrophoresis (PFGE)-types I-IV: A, C, F: 1987/I; B, E: 2369/II; D1: 1961/III; D2: 1954/IV; A-C: a large amount of biofilm material exhibiting; B, D: bacterial microcolonies; E: amorphous material on the catheter surface is evident; C, F: presence of hollow voids indicative of mature biofilm formation on surfaces polyurethane catheters.

Fig. 4:. biofilm formation (24 h incubation) on polystyrene surface by Corynebacterium striatum strains evaluated by a semiquantitative microplate assay. Effect of human plasma fibrinogen (Fbg) on biofilm formation by representative strains of pulsed-field gel electrophoresis (PFGE)-types I-IV. Experiments were performed in triplicate and the means standard deviations of three independent experiments. *: p < 0.05; #: p > 0.05.