Ivana Gobin

Experimental Legionella longbeachae infection in intratracheally inoculated mice

This study established an experimental model of replicative Legionella longbeachae infection in A/J mice. The animals were infected by intratracheal inoculation of 10(3)-10(9) c.f.u. L. longbeachae serogroup 1 (USA clinical isolates D4968, D4969 and D4973). The inocula of 10(9), 10(8), 10(7) and 10(6) c.f.u. of all tested L. longbeachae serogroup 1 isolates were lethal for A/J mice. Inoculation of 10(5) c.f.u. L. longbeachae caused death in 90 % of the animals within 5 days, whilst inoculation of 10(4) c.f.u. caused sporadic death of mice. All animals that received 10(3) c.f.u. bacteria developed acute lower respiratory disease, but were able to clear Legionella from the lungs within 3 weeks. The kinetics of bacterial growth in the lungs was independent of inoculum size and reached a growth peak about 3 logarithms above the initial inoculum at 72 h after inoculation. The most prominent histological changes in the lungs were observed at 48-72 h after inoculation in the form of a focal, neutrophil-dominant, peribronchiolar infiltration. The inflammatory process did not progress towards the interstitial or alveolar spaces. Immunohistological analyses revealed L. longbeachae serogroup 1 during the early phase of infection near the bronchiolar epithelia and later co-localized with inflammatory cells. BALB/c and C57BL/6 mice strains were also susceptible to infection with all L. longbeachae serogroup 1 strains tested and very similar changes were observed in the lungs of infected animals. These results underline the infection potential of L. longbeachae serogroup 1, which is associated with high morbidity and lethality in mice.

Infections caused by nonpneumophila species of Legionella.

There are 52 recognized species of the genus Legionella of which 25 have been implicated in human disease. These organisms are prevalent within both natural and man-made aquatic environments in which they survive as parasites of protozoa. The vast majority of legionellosis is caused by the well studied opportunistic, intracellular pathogen Legionella pneumophila. However, other species of Legionella are capable of causing human disease, though primarily in immunocompromised people and not in large community outbreaks like those that can occur with L. pneumophila. L. longbeachae and L. micdadei account for the majority of nonpneumophila legionellosis with most other Legionella species associated with only a few reported cases. L. longbeachae is a unique Legionella species that dwells in soil and is particularly prevalent within specific geographical locations. Nonpneumophila species of Legionella can cause a wide range of infections not typically categorized as legionellosis and mixed infections of Legionella species can also occur. These clinical occurrences combined with diagnostic techniques that are specific for L. pneumophila, such as the urine antigen test, have led to the underdiagnosis of nonpneumophila legionellosis and therefore less effective therapies being administered. Little is known about the pathogenic mechanisms and intracellular lifestyle of nonpneumophila Legionella species and how this compares to L. pneumophila. Genome sequencing may provide a means for further understanding of these organisms and lead to more effective differential diagnosis of legionellosis.

Systemic and local CC chemokines production in a murine model of Listeria monocytogenes infection.

Repeated intragastric inoculation of Listeria monocytogenes into BALB/c mice resulted in prolonged bacteraemia and severe hepatic infection. Bacteria could also be isolated from the brain tissue of all experimental mice. During the inflammatory process, chemokine concentrations typically increased at the local site in comparison to the systemic level. The liver-to-serum ratio was more pronounced in the case of macrophage inflammatory protein 1α (MIP-1α), suggesting its role in the inflammatory response in the liver. The ratio of brain-to-serum concentration of monocyte chemoattractant protein 1 (MCP-1) remained the same as in the control animals, while it was lower in the infected mice, both in the case MIP-1α and in the case of regulated on activation, normal T cell expressed and secreted (RANTES). This is in correlation with slight inflammatory infiltrates found in the brain tissue early in infection.

Three new Lactobacillus plantarum strains in the probiotic toolbox against gut pathogen Salmonella enterica serotype Typhimurium

The benefits of probiotic bacteria have been widely explored. However, fermented foods and digestive system of humans and animals are an inexhaustible source of new potentially probiotic microorganisms. In this study we present three new Lactobacillus plantarum strains isolated from different dairy products: cows cheese, sheeps cheese and whey. In order to determine the antibacterial activity of yet unexplored L. plantarum strains against Salmonella enterica serotype Typhimurium, in vitro competition and co-culture tests were done. Furthermore, adhesion of these strains to Caco-2 cells and their influence on the adhesion of Salmonella were tested. Results showed the potential probiotic activity of isolated strains. L. plantarum strains survived in the presence of 1% bile salts, they possessed acidification ability, antibacterial activity and significantly attenuated the growth of S. Typhimurium in brain heart infusion broth. All tested L. plantarum strains were able to adhere to Caco-2 cells and significantly impair the adhesion of S. Typhimurium. All three L. plantarum strains exhibited significant probiotic potential and anti-Salmonella activity; therefore, further testing on in vivo models should follow.

Carvacrol induces cytotoxicity in human cervical cancer cells but causes cisplatin resistance: involvement of MEK-ERK activation

Carvacrol has been shown to possess anticancer activity, but the mechanism is unknown, as well as the possibility of interaction with anticancer drugs. The aim of this study was to investigate the role of mitogen‐activated protein kinase kinase (MEK)/extracellular signal‐regulated kinase (ERK) signaling in carvacrol‐induced human cervical cancer HeLa cell cytotoxicity. In addition, we studied sensitization of HeLa cells to cisplatin (CP) by carvacrol. Both carvacrol and CP showed dose‐dependent cytotoxicity against HeLa cells and activated ERK1/2. The MEK inhibitor PD325901 suppressed ERK expression and further increased cytotoxicity of carvacrol but increased viability of CP‐treated cells by modulating apoptosis. The MEK inhibitor also increased microtubule‐associated protein 1A/1B‐light chain 3 beta expression in CP treatment. Cotreatment with CP and carvacrol resulted in increased viability of the cancer cells compared with CP treatment, which was associated with the suppression of apoptosis. MEK inhibition decreased the cell viability, without changes in apoptosis. Concomitantly, carvacrol increased CP‐induced expression of light chain 3 beta, which was enhanced by MEK inhibition. The results of the current study suggest the opposite role of ERK1/2 in carvacrol and CP‐induced HeLa cell cytotoxicity. Interestingly, carvacrol induced CP resistance in HeLa cells through ERK1/2‐independent suppression of apoptosis and ERK1/2‐dependent modulation of autophagy.

Medicinal herbs and herbal preparations for the treatment of urinary infections

Zbog sve vece rezistencije bakterija na poznate antibiotike, u novije vrijeme provodi se niz istraživanja s ciljem pronalaženja prirodnih tvari, po

Influence of essential oil Helichrysum italicum (Roth) G. Don on the formation of non-tuberculous mycobacterial biofilm

Cilj: Ispitati antimikrobni i antioksidacijski ucinak te sposobnost inhibicije biofilma etericnog ulja (EU) smilja [Helichrysum italicum (Roth) G. D

In vitro Antiproliferative and Antimicrobial Activity of the Essential Oil from the Flowers and Leaves of Helichrysum italicum (Roth) G. Don Growing in Central Dalmatia (Croatia)

Abstract In the present paper, chemical composition, in vitro antimicrobial and antiproliferative activity of the essential oil from the flowers and leaves of Helichrysum italicum (Roth) G. Don (Central Dalmatia, Croatia) as a potential replacement for standard antibiotics and chemotherapeutic agents was analyzed. Essential oil was isolated by steam distillation and analyzed by GC/MS. Antimicrobial activity was carried out by agar-well diffusion and microdilution assays with Gram (+), Gram (-) bacteria and one yeast. Antiproliferative effect, apoptosis induction and cell death on cancer cell lines: HeLa, MCF-7, SW620, CFPAC-1 and MIA PaCa-2 were analyzed by cell viability and Annexin-V assay as well as by flow cytometric analysis. In essential oil, α-pinene, γ-curcumene and neryl acetate was found as major compounds. The antimicrobial assays, showed that essential oil had weak to moderate antimicrobial potential with S. aureus and S. epidermidis as the most sensitive bacterial strains. Essential oil treatment possessed moderate antiproliferative impact on MCF-7 and HeLa cell lines, while analyzing cell cycle treatment had no significant effect on tested cells except on MIA PaCa-2 with the highest cells increase in sub G1 phase cell cycle. However, treatment caused significantly induction of apoptosis in MCF-7 and HeLa cells, but not in MIA PaCa-2 cells. In this cell line, multiple cell death mechanism existed with involving apoptosis, senescence or necrosis. Results of the study provide a promising basis for the evaluation of the potential use of essential oil from H. italicum (Roth) G. Don as a source of alternative nature antibiotics or anticancer agents for the prevention or treatment of different diseases.

Reduced contamination and infection via inhibition of adhesion of foodborne bacteria to abiotic polystyrene and biotic amoeba surfaces

Adhesion of foodborne pathogens to materials of industrial surfaces is an important step in their transmission through the food chain. Adhesion is also a prerequisite for bacterial colonisation within a host, to enable intracellular invasion. We define a strategy to reduce contamination and infection by Listeria monocytogenes, Campylobacter jejuni and Escherichia coli using an ethanol extract of Alpinia katsumadai seeds (AlpE) and epigallocatechin gallate (EGCG) as anti- adhesive agents. We show for the first time that AlpE and EGCG reduce adhesion of individual cultures to polystyrene (AlpE, up to 10.6% ; EGCG, up to 39.7%) and to the amoeba Acanthamoeba castellanii (AlpE, up to 52.6% ; EGCG, up to 53.4%). The combination of AlpE/EGCG significantly reduced C. jejuni adherence to the abiotic (45.5%) and biotic (52.2%) surfaces. Thus, using natural agents from plants at low doses, we can potentially reduce the primary source of food contamination and a frequent source of infections.

Evaluation of the Antioxidant Capacity, Antimicrobial and Antiproliferative Potential of Fir (Abies alba Mill.) honeydew honey collected from Gorski kotar (Croatia)

SUMMARY The paper examines the antiproliferative, antimicrobial and antioxidative effects of fir (Abies alba Mill.) honeydew honey from mountain region of Croatia (Gorski kotar) as a potential replacement for standard antibiotics and chemotherapeutic agents. Cell viability, annexin V assay and flow cytometry analysis served to analyse the antiproliferative effect on, apoptosis induction in and cell death of cancer cell lines: HeLa, MCF-7, SW620, CFPAC-1, MIA PaCa-2 and normal diploid human fibroblasts (BJ). Antimicrobial activity was tested against Staphylococcus and Acinetobacter strains by agar well diffusion and microdilution assays. The DPPH˙ assay determined the radical scavenging activity, while mathematical models helped to evaluate the kinetic data of DPPH˙ inhibition. Antiproliferative effect on all tested cell lines and the prominent effect on normal diploid human fibroblasts (BJ), colorectal adenocarcinoma (SW620, metastatic) and breast epithelial adenocarcinoma (MCF-7, metastatic) was observable. The mechanisms of antiproliferative effect included accumulation of cells in the sub-G1 phase in all tested cells and induction of apoptosis in SW620 and MCF-7 cells predominantly. The antibacterial assays showed that antibiotic-resistant strains of both bacteria, including multi-resistant strain A. baumannii ATCC® BAA-1605™, were sensitive to all tested honey samples. Radical scavenging assay suggests that antioxidants present in the honey possess different radical suppressing abilities and that they react at different rates with radicals, thereby causing two steps of reaction. The results of the study indicate that Croatian fir honeydew honey has a therapeutic potential due to the strong biological activity and can serve to protect human health.