Antioxidant potential and protective effects of bee pollen extract against Salmonella induced hepatic and renal toxicity in BALB/c mice

Apicultural products comprise honey, bee pollen, propolis, bee wax and royal jelly which are known for their medicinal and health promoting properties. Among these, bee collected pollen allure much attention for its high nutritional properties. Here, we have investigated the protective role of bee pollen against Salmonella typhimurium induced biochemical alteration in BALB/c mice. Experimental animals (BALB/c mice) were divided equally into 10 different groups including normal and treated. Oxidative stress was induced by injecting Salmonella typhimurium (0.2 mL of 2×104 CFU/mL) intraperitoneally in mice. Bacteria induced sufficient alterations in serum enzymes within 5 days. Aqueous extracts of bee pollen of different crops (250 mg/kg) were administrated orally to control and experimental mice for 21 days. Then, hepatic and renal enzymes were measured with the help of standardized kits. Results of this study have revealed that bacterial infection increases the levels of the hepatic and renal enzymes levels (P <0.001) but after treatment with bee pollen extracts, altered levels of enzymes were normalized up to the normal levels. This normalization was highest with bee pollen of Helianthus annus. Administration of bee pollen alone did not produce any negative effects in mice.

Subinhibitory concentration of ciprofloxacin targets quorum sensing system of Pseudomonas aeruginosa causing inhibition of biofilm formation & reduction of virulence.

Background & objectives: Biofilms formed by Pseudomonas aeruginosa lead to persistent infections. Use of antibiotics for the treatment of biofilm induced infection poses a threat towards development of resistance. Therefore, the research is directed towards exploring the property of antibiotics which may alter the virulence of an organism besides altering its growth. The aim of this study was to evaluate the role of subinhibitory concentration of ciprofloxacin (CIP) in inhibiting biofilm formation and virulence of P. aeruginosa. Methods: Antibiofilm potential of subinhibitory concentration of CIP was evaluated in terms of log reduction, biofilm forming capacity and coverslip assay. P. aeruginosa isolates (grown in the presence and absence of sub-MIC of CIP) were also evaluated for inhibition in motility, virulence factor production and quorum sensing (QS) signal production. Results: Sub-minimum inhibitory concentration (sub-MIC) of CIP significantly reduced the motility of P. aeruginosa stand and strain and clinical isolates and affected biofilm forming capacity. Production of protease, elastase, siderophore, alginate, and rhamnolipid was also significantly reduced by CIP. Interpretation & conclusions: Reduction in virulence factors and biofilm formation was due to inhibition of QS mechanism which was indicated by reduced production of QS signal molecules by P. aeruginosa in presence of subinhibitory concentration of CIP.

Attenuation of quorum sensing controlled virulence of Pseudomonas aeruginosa by cranberry.

Background & objectives: Emergence of antimicrobial resistance in Pseudomonas aeruginosa has led to the search for alternative agents for infections control. Natural products have been a good alternative to present antibiotics. The present study was undertaken to evaluate the effectiveness of cranberry in attenuation of virulence of P. aeruginosa in experimental urinary tract infection (UTI) in mouse model. Efforts were also directed to explore the action of cranberry towards virulence of P. aeruginosa through quorum sensing (QS) inhibition. Methods: Efficacy of cranberry was evaluated in an experimental UTI mouse model and on production of QS signals, alginate, pyochelin, haemolysin, phospholipase-C, cell-surface hydrophobicity, uroepithelial cell-adhesion assay and biofilm formation by already standardized methods. Results: Presence of cranberry showed significant decline in the production of QS signals, biofilm formation and virulence factors of P. aeruginosa in vitro (P<0.001). Further, cranberry was found to be useful in prevention of experimental UTI in mouse model as indicated by reduced renal bacterial colonization and kidney tissues destruction. Interpretation & conclusions: The findings of the present study indicated that cranberry inhibited QS and hence elaboration of virulence factors of P. aeruginosa. It also affected the adherence ability of this pathogen. This approach can lead to the discovery of new category of safe anti-bacterial drugs from dietary sources such as cranberry with reduced toxicity without the risk of antibiotic resistance.

Inhibitory effect of polyunsaturated fatty acids on apoptosis induced by Streptococcus pneumoniae in alveolar macrophages.

Background & objectives: Apoptosis is considered as a major defense mechanism of the body. Multiple pathogens induce macrophage apoptosis as a mode of immune evasion. In earlier studies, n-3 polyunsaturated fatty acids (PUFA) have been reported to be protective against neuronal apoptosis and neuronal degeneration, seen after spinal cord injury. In this study, we tried to evaluate the role of n-3 polyunsaturated fatty acids on the process of macrophage phagocytic activity and apoptosis in mice. Methods: Mice were divided into three groups (n=60); Group I was fed on sea cod oil; Group II on flaxseed oil supplementation for 9 wk along with standard laboratory chow diet. Group III was fed on standard diet and served as control. After supplementation, phagocytic and apoptotic (morphological staining: acridine orange plus ethidium bromide; H-33342 plus propidium iodide staining and DNA ladder formation) activities of mouse alveolar macrophages were assessed. Results: Alveolar macrophages (obtained from sea cod oil and flaxseed oil fed group mice) showed significant increase in bacterial uptake as well as intracellular killing (P< 0.05) of Streptococcus pneumoniae. Significant decrease (P<0.05) in apoptotic cells was observed among alveolar macrophages from sea cod and flaxseed oil fed mice whereas maximum apoptosis was observed in control alveolar macrophages on interaction with bacteria in vitro which was confirmed by DNA laddering. Interpretation & conclusions: These findings suggest that dietary supplementation with n-3 polyunsaturated fatty acids to mice led to enhanced phagocytic capability of their alveolar macrophages as well as provided protection against apoptosis upon challenge with S. pneumoniae.

Screening & profiling of quorum sensing signal molecules in Pseudomonas aeruginosa isolates from catheterized urinary tract infection patients.

Background & objectives: Catheter associated urinary tract infections are the second most common nosocomial infections and Pseudomonas aeruginosa is the third most common organism responsible for these infections. In this study P. aeruginosa isolates from catheterized urinary tract infection patients were screened and profiled for the presence of different type of quorum sensing (QS) signal molecules. Methods: Screening and quantitation of AHLs was done by using cross feeding assay and by determining β-galactosidase activity respectively using Escherichia coli MG4 as reporter strain. Further, AHL profiles were determined by separating AHLs on TLC coupled with their detection using Chromobacterium violaceum CV026 and Agrobacterium tumifaciens A136 biosensor strains. Results: All uroisolates from catheterized patients having urinary tract infections were found to be producers of QS signal molecules. There were differences in amounts and type of AHL produced amongst uroisolates of P. aeruginosa. Several AHLs belonging to C4-HSL, C6-HSL, oxo-C6-HSL, C8-HSL, C10-HSL and C12-HSL were determined in these strains. Interpretation & conclusions: Simultaneous use of more than one reporter strain and assay method proved useful in determining the AHLs profile in uroisolates of P. aeruginosa. Observed differences in the amounts and types of AHLs may reflect differences in virulence potential of P. aeruginosa to cause UTIs which can be further confirmed by employing animal model system. The present study speculates that production of QS signal molecules may act as a new virulence marker of P. aeruginosa responsible for causing catheter associated UTIs and can be considered as futuristic potential drug targets towards treatment of UTIs.

Phenotypic characters of urinary isolates of Pseudomonas aeruginosa & their association with mouse renal colonization.

BACKGROUND & OBJECTIVE: Very few studies regarding production of virulence factors in different predominant serotypes of uropathogenic Pseudomonas aeruginosa are available and they have not been correlated to in vivo pathogenicity in the urinary tract. This study was carriedout with the objective to analyze the phenotypic characters of uroisolates of P. aeruginosa in vitro and to study the association of these virulence traits with their ability to cause nephropathogenicity in mouse model of ascending urinary tract infection (UTI). METHODS: Protease, elastase, alginate, haemolysin, pyochelin, pyoverdin and phopholipase C were measured using standard protocols in 18 uroisolates of P. aeruginosa isolated from patients suffering from complicated UTIs. An ascending model of pyelonephritis was established in Swiss Webster (LACA) female mice with these isolates. Quantitative bacterial count and histopathological evaluation of mouse renal tissue was done which were then assessed for a possible association with elaboration of virulence factors. RESULTS: All isolates of P. aeruginosa were able to colonize renal tissue of mice. However, renal counts varied amongst different isolates producing different virulence factors. Isolates producing high levels of haemolysin along with other virulence factors were able to colonize and multiply more in mouse renal tissue as compared to those producing low levels of haemolysin. INTERPRETATION & CONCLUSION: The findings of this study indicated an association between haemolysin production and renal colonization. High level of haemolysin production in vitro could be used as surrogate information for assessing pyelonephritic potential of P. aeruginosa.

In vitro comparative kinetics of adhesive and haemolytic potential of T. vaginalis isolates from symptomatic and asymptomatic females.

The host parasite relationship and pathogenic mechanisms of the commonly reported sexually transmitted urogenital disease, trichomoniasis, are poorly understood. This study was planned to correlate the adhesion properties of Trichomonas vaginalis isolates from symptomatic and asymptomatic women to vaginal epithelial cells in vitro (in presence and absence of L. acidophilus) and to ascertain the haemolytic activity of the isolates, in order to assess these properties as possible markers of pathogenicity. Cytoadherence assay study shows the significant difference in adhesion only up to first 15 minutes of incubation in symptomatic versus asymptomatic isolates. The presence of L. acidophilus was found to be more effective in enhancing the attachment of T. vaginalis in a time dependent manner mostly operative through its pH lowering effect, whereas the excretory secretory products of L. acidophilus reduced the attachment in case of both symptomatic and asymptomatic isolates. Amount of haemoglobin released by isolates from symptomatic patients was significantly higher than by the isolates from asymptomatic women. This investigation forms the basis for future studies to explore the role of other known virulence factors of T. vaginalis in initiation and persistence of vaginal infection by the parasite.

Induction & resolution of lobar pneumonia following intranasal instillation with Klebsiella pneumoniae in mice.

BACKGROUND & OBJECTIVES: Pneumonia caused by Klebsiella pneumoniae is important due to its high morbidity and mortality, especially in context of nosocomial infections. Many experimental studies have focused on the induction and progression of infection till it peaks, but the process of resolution has not been described. In the present study, we successfully attempted to establish an acute respiratory tract infection model in BALB/c strain of mice with K. pneumoniae employing a simple, reproducible intranasal instillation method. METHODS: Experimental pneumonia was induced by two strains of K. pneumoniae in BALB/c mice following intranasal instillation, and the course of pneumonia was studied by bacteriological and histopathological evaluation of the lung tissue. RESULTS: Both the strains were similar in their ability to induce infection which peaked on day 3, post infection. However, a strain dependent difference in relation to bacterial load and the process of resolution was observed. INTERPRETATION & CONCLUSION: The present study provides a model of lobar pneumonia produced by K. pneumoniae which can be useful for studying therapeutic and preventive interventions.