The influence of Lactobacillus acidophilus-derived surfactants on staphylococcal adhesion and biofilm formation.

The ability of surfactants obtained from three Lactobacillus acidophilus strains to inhibit Staphylococcus aureus and S. epidermidis biofilms was evaluated. Their influence was determined on bacterial initial adhesion, biofilm formation and dispersal using MTT-reduction assay, confocal laser scanning microscopy and image PHLIP analysis. The number of adhering S. aureus and S. epidermidis cells after a 3-h co-incubation with biosurfactants was reduced by 5-56 % in a strain-and dose-dependent manner. S. epidermidis-and, to a lower extent, in S. aureus-biofilm formation was also inhibited in the presence of the tested surfactants. The addition of surfactants to preformed mature biofilms accelerated their dispersal, and changed the parameters of biofilm morphology. The L. acidophilus-derived surfactants inhibit bacterial deposition rate and biofilm development (and also its maturation) without affecting cell growth probably due to the influence on the cell-surface hydrophobicity of staphylococci.

Staphylococcus aureus biofilm as a target for single or repeated doses of oxacillin, vancomycin, linezolid and/or lysostaphin.

Due to high resistance, standard chemotherapy of biofilm-associated staphylococcal infections is ineffective and a number of alternative approaches to antimicrobial treatment have been proposed. Minimum inhibitory concentration (MIC) and biofilm inhibitory concentration (BIC) of oxacillin (Oxa), vancomycin (Van), linezolid (Lzd) and lysostaphin (Lss) as well as the possible synergistic effect of the antibiotics and lysostaphin were determined. The Lss susceptibility of Staphylococcus aureus planktonic and bio-film cultures varied and was strain-dependent. The synergistic effect of sub-BIC(Lss)+Oxa was observed for methicillin-sensitive S. aureus (MSSa) and methicillin-resistant S. aureus (MrSa), but not for heterogeneously vancomycin-resistant S. aureus (V(h)Sa) biofilm. Van with sub-BICL(Lss) was effective against M(s)Sa and MrSa biofilm, when applied in three subsequent doses. Only sub-BICL(Lss)+Lzd combination, given as three cycles therapy, was effective in disruption of all 3 (M(s)Sa, M(r)Sa, V(h)Sa) biofilms.

Superantigen types in Staphylococcus aureus isolated from patients with cystic fibrosis.

The screening of 17 SAg genes of S. aureus isolated from the sputum of cystic fibrosis (CF) patients revealed that among 47 genetically different strains, 39 (83 %) carried SAg genes. Superantigens forming enterotoxin gene cluster were detected in 20 strains. The 2nd most common superantigen type was selk detected in 13 strains. In 9 strains, selk occurred together with the sea gene. Out of 74 strains recovered from nasal carriers, 56 (75 %) were found to carry SAg genes, 38 carried egc genes, while selk was detected in 5 strains. The predominant SAg types in both investigated S. aureus populations were egc and selk/sea, but selk gene frequency was significantly higher in the CF-derived strains.

Specific immune response to staphylococcal antigens during long-lasting biomaterial implantation.

Biomaterial-associated infections caused by staphylococci are one of the main therapeutic problems in modern medicine. There is no doubt that local disfunction of polymorphonuclear leukocytes and macrophages predisposes to such infections. However, it is not clear how implantation of a foreign body influences the antibacterial immune response. We analyzed some parameters of the specific immune response to staphylococcal antigens, in mice implanted for 3 months with heparinized polyethylene. Three weeks before the evaluation of the immune response, mice (implanted and non-implanted) were infected i.p. with 2 x 10(7) cells of Staphylococcus aureus Cowan 1. The proliferation of splenocytes was determined on the basis of [3H]thymidine incorporation in cultures stimulated with staphylococcal lipoteichoic acid, protein A, alpha-toxin, or phytohemagglutinin. Moreover, the level of specific antibodies to staphylococcal antigens was determined in serum samples (ELISA with the antigens lipoteichoic acid, protein A, and alpha-toxin). The data obtained indicate that long-lasting implantation caused evident changes in proliferative activity of lymphocytes and in humoral response to staphylococcal antigens. It enhanced spontaneous and lipoteichoic acid- or alpha-toxin-stimulated proliferation of splenocytes, in vitro. In contrast, heparinized polyethylene-implanted animals showed a significant decrease in the production of anti-protein A IgG2b and anti-alpha-toxin IgG2a and IgG2b.

[Detection of bacterial biofilm on medical biomaterials]. / Wykrywanie biofilmu bakteryjnego na biomaterialach medycznych.

This study was performed to assess the value TTC assay in the diagnosis of biomaterial-associated infections. In this assay, soluble colourless TTC is reduced to insoluble red formazan by electron transfer associated with active oxidative bacterial metabolism and is precipitated intracellularly. Microbial adhesion and biofilm formation on the surface of medical prosthetic devices (vesicular and urinary catheters) made of various polymers (PTFE, H-PE, PCW, SL), were determined. The microorganisms which are most often isolated in medical device-associated infections: S. aureus, S. epidermidis, E. faecalis, E. coli, P. vulgaris, P. aeruginosa, C. albicans, were included into the study. The obtained results indicate that the assay using TTC as a metabolic indicator of bacterial biofilm presence, is technically simple to conduct with minimal setup time. Even when classical cultures yielded no bacterial growth, TTC assessments demonstrated bacterial biofilms. TTC assay could be recommended as a quick routine method for confirmation of biomaterial device-associated infection.

Antimicrobial and anti-biofilm properties of new taxodione derivative from hairy roots of Salvia austriaca.

The aim of the present report was to evaluate antimicrobial/anti-biofilm activity of 7-(2-oxohexyl)-taxodione, a novel taxodione derivative isolated from n-hexane extract of Salvia austriaca hairy roots. Antimicrobial assays showed that 7-(2-oxohexyl)-taxodione was at least 4 times more active than taxodione against methicillin-susceptible as well against methicillin-resistant staphylococci with MIC of 1.25-2.5 µgml(-1). This compound was less active against vancomycin-resistant enterococci (VRE), on the same level as taxodione (MIC ranged 10.0-20.0 µgml(-1)). The presence of 7-(2-oxohexyl)-taxodione in the culture medium (at MIC, ½ MIC or » MIC) decreased adhesion of staphylococci to abiotic surfaces, which in turn caused a reduction in biofilm formation during 24h, by approximately 25-30%. Also, the extent of established biofilm eradication was found to be significant, although it required an increased concentration of the compound. This is the first report on the antimicrobial activity of this, up to now not known compound, isolated from transformed roots of S. austriaca.

Bacteria competing with the adhesion and biofilm formation by Staphylococcus aureus.

The activity of antagonistic substances produced by Pseudomonas aeruginosa and Lactobacillus acidophilus against the planktonic and sessile populations of Staphylococcus aureus strains was demonstrated. The strongest effects were caused by probiotic L. acidophilus strain - bacteriocin-like inhibitory substances (BLIS) positive. However, the S. aureus A3 growth, adhesion and biofilm formation was also limited by cell-free supernatant of L. acidophilus H-1 (BLIS negative). Moreover, competitive direct interactions were observed between staphylococci and the above bacteria, which influenced the formation of dualspecies aggregates on the surface.

Granulocyte-macrophage colony-stimulating factor (GM-CSF)-coated implants and their potential for reducing biomaterial-associated infection in neutropenic hosts.

The incidence of infections associated with the use of medical biomaterials is high for skin-penetrating devices, when microbes of the normal skin flora like coagulase-positive and coagulase-negative staphylococci dominate as causative organisms. The most serious ones are infections in immunocompromised individuals. A mouse model of subcutaneous staphylococcal infection yielding abscesses in cyclophosphamide-induced neutropenic mice implanted with heparinized polyethylene (H-PE) was used. The present study addresses the question of the effects of implant modification with recombinant granulocyte-macrophage stimulating factor (rGM-CSF) on the course of infection. Our findings demonstrate that such modification reduces the proliferation of bacteria within the abscess and as a consequence limits the dissemination of bacteria from the local infection induced in the neutropenic host.

The virulence of Staphylococcus aureus isolates differing by siderophore production.

In previous study we demonstrated that Staphylococci aureus clinical and environmental isolates differ by siderophore production (Lisiecki et al., 1997), the aim of the present study was to check a possible role of siderophore-dependent iron acquisition system of outcome of staphylococcal diseases. The systemic and local staphylococcal infections were induced in mice by inoculation of three S. aureus strains differing by siderophore production. We found that S. aureus B 47 strain characterized by enhanced siderophore activity was more virulent in both systemic and local infection models and it was more resistant to anti-bacterial activity of neutrophils than S. aureus B 63 and B 32 strains expressing weaker siderophore production. The results suggest that effective siderophore-dependent iron acquisition system may be beneficial to S. aureus strains in their pathogenic activity in vivo.

[A comparison of titers of immunoglobulins A and G reacting with Helicobacter pylori antigens in patients with unstable angina and symptomless blood donors]. / Porównanie mian immunoglobulin klasy IgG oraz IgA reagujacych z antygenami Helicobacter pylori w grupie pacjentów z niestabilna choroba wiencowa i w grupie zdrowych krwiodawców.

The aim of the study was to estimate the prevelance and distribution of titers of immunoglobulins IgA and IgG reacting with glycine extract of Helicobacter pylori antigens in the group of patients with unstable angina and in the group of symptomless blood donors. The sera of 30 patients and 33 healthy individuals (blood donors) were assessed using ELISA test. Comparing the results from these two groups we observed that distributions of IgG antibodies were not concordant: the higher titers were more typical for the group ++of patients with unstable angina then for blood donors. This suggests that intensive humoral response on H. pylori antigens may play a role in aggravation of symptoms of coronary artery atherosclerosis.

Altered immune response to staphylococcal antigens in long-lasting implanted mice.

Staphylococcal infections constitute one of the main problems associated with clinical applications of various prosthetic medical devices (biomaterials). As the magnitude of the infection risk depends often on the duration of device installation, and the incidence of infections is higher in skin-penetrating devices, we studied some parameters of specific immune response to staphylococcal antigens in mice subcutaneously (s.c.) implanted for three months with heparinized polyethylene (H-PE). Three weeks before the evaluation of immune response, mice (implanted and non-implanted) were s.c. infected with 10(7) of Staphylococcus aureus Cowan 1. The proliferation of lymph node cells was determined on the basis of 3H-thymidine incorporation in 3-days cultures stimulated with: staphylococcal lipoteichoic acid (LTA), protein A (SpA), alpha-toxin, or with phytohemagglutinin (PHA). Moreover, the levels of specific antibodies to staphylococcal antigens were determined in serum samples (ELISA against: LTA, SpA, alpha-toxin). The data obtained indicate that long-lasting implantation caused evident changes in proliferative activity of lymphocytes and humoral response to staphylococcal antigens. It enhances alpha-toxin and LTA stimulated proliferation of lymph node lymphocytes in vitro. In contrast, H-PE-implanted animals demonstrated a significant decrease in the production of anti-SpA IgG2a and IgG2b and increase in the synthesis of anti-LTA IgG1 antibodies.

Characterization of Staphylococcus aureus strains isolated from cystic fibrosis patients by conventional and molecular typing.

The phenotypic and genotypic characteristics of Staphylococcus aureus strains isolated from respiratory tract of cystic fibrosis (CF) patients were investigated. Slime production, cell-surface hydrophobicity, type of capsular polysaccharide, profile of heteroresistance to methicillin and Sma I restriction profiles were evaluated. S. aureus CF strains have been shown to be heterogeneous in respect to several important features. All of them were slime producing with variation in colony morphology. High or moderate cell-surface hydrophobicity (CSH) was found for, respectively, 16.2% and 83.8% strains. Thirty strains were resistant to methicillin, 60% of them showed heteroresitance and 40% were homoresistant. It was found that 59.6% of strains produced capsular polysaccharides (CP) of 5 or 8 type. Among CP5/CP8 strains, CP8 was the predominant type (81.1%). Typing of 62 CF strains by macrorestriction analysis of chromosomal DNA revealed several major types, differing in their SmaI profiles with a similarity coefficient lower than 0.4. Some of the strains isolated from the same patient at different times of hospitalization, as well as strains isolated at the same time from the relatives, were identical in their PFGE pattern.