Both biofilm cytotoxicity and monocytes' adhesion may be used as estimators of enterococcal virulence

Our study aimed to identify markers of enterococci's virulence potential by evaluating the properties of strains of different sites of isolation. Enterococcal strains were isolated as commensals from faeces and as invasive strains from the urine and blood of patients from the University Clinical Centre, Gdańsk, Poland. Changes in monocytes' susceptibility to the cytotoxic activity of isolates of different origins and their adherence to biofilm were evaluated using a flow cytometer. The bacterial protein profile was estimated by matrix assisted laser desorption ionization-time of flight mass spectrometer. The cytotoxicity of biofilm and monocytes' adherence to it were the most accurate factors in predicting the prevalence of the strain in the specific niche. Additionally, a bacterial protein with mass-to-charge ratio (m/z) 5000 was found to be responsible for the increased bacterial cytotoxicity, while monocytes' decreased adherence to biofilm was linked with the presence of proteins either with m/z 3330 or 2435. The results illustrate that monocytes' reaction when exposed to the bacterial biofilm can be used as an estimator of pathogens' virulence potential. The observed differences in monocytes' response are explainable by the bacterial proteins' profile. Additionally, the results indicate that the features of both bacteria and monocytes impact the outcome of the infection.

Changes of urine isolates of Escherichia coli and Klebsiella pneumoniae biofilm affect monocytes' response

The Gram negative rods as Escherichia coli and Klebsiella pneumoniae belong to the most common etiology agents of urinary tract infections. The aim of our study was to assess the diversity of biofilm formed in different urinary tract diseases and their impact on monocytes’ adherence and activation. The bacteria were obtained from patients with different kidney problems. Some of the patients were after renal transplantation, some of them were not. Changes in the size and granularity of monocytes, as well as their adherence to biofilm, were assessed using FACSVerse flow cytometer after 1 h co-incubation of monocytes and bacterial biofilm in 37 °C. The obtained results were validated against monocytes incubated without bacteria. The isolates from patients with chronic kidney disease formed the most adherent biofilm regardless the presence or absence of inflammatory reaction. Adherence of monocytes also increased during therapy with immunosuppressive agents, but monocytes’ response was different when cyclosporine or tacrolimus were used. Additionally the presence of inflammatory reaction in patients with kidney disease modified the monocytes response when the immunosuppressive drugs were used. Considering the obtained results, we conclude that the changes of monocytes’ morphology in response to biofilm formed by Gram negative rods could become a tool to detect urinary tract infection, especially in those groups of patients, where the knowledge of ongoing inflammation is important and the standard tools fail to detect it.

Cytokine Levels in the In Vitro Response of T Cells to Planktonic and Biofilm Corynebacterium amycolatum

Unravelling of the interplay between the immune system and non-diphtheria corynebacteria would contribute to understanding their increasing role as medically important microorganisms. We aimed at the analysis of pro- (TNF, IL-1β, IL-6, IL-8, and IL-12p70) and anti-inflammatory (IL-10) cytokines produced by Jurkat T cells in response to planktonic and biofilm Corynebacterium amycolatum. Two reference strains: C. amycolatum ATCC 700207 (R-CA), Staphylococcus aureus ATCC 25923 (R-SA), and ten clinical strains of C. amycolatum (C-CA) were used in the study. Jurkat T cells were stimulated in vitro by the planktonic-conditioned medium (PCM) and biofilm-conditioned medium (BCM) derived from the relevant cultures of the strains tested. The cytokine concentrations were determined in the cell culture supernatants using the flow cytometry. The levels of the cytokines analyzed were lower after stimulation with the BCM when compared to the PCM derived from the cultures of C-CA; statistical significance (p < 0.05) was observed for IL-1β, IL-12 p70, and IL-10. Similarly, planktonic R-CA and R-SA stimulated a higher cytokine production than their biofilm counterparts. The highest levels of pro-inflammatory IL-8, IL-1β, and IL-12p70 were observed after stimulation with planktonic R-SA whereas the strongest stimulation of anti-inflammatory IL-10 was noted for the BCM derived from the mixed culture of both reference species. Our results are indicative of weaker immunostimulatory properties of the biofilm C. amycolatum compared to its planktonic form. It may play a role in the persistence of biofilm-related infections. The extent of the cytokine response can be dependent on the inherent virulence of the infecting microorganism.