Potential pathogenic role of aggregative- adhering Corynebacterium diphtheriae of different clonal groups in endocarditis

Invasive diseases caused by Corynebacterium diphtheriae have been described increasingly. Several reports indicate the destructive feature of endocarditis attributable to nontoxigenic strains. However, few reports have dealt with the pathogenicity of invasive strains. The present investigation demonstrates a phenotypic trait that may be used to identify potentially invasive strains. The study also draws attention to clinical and microbiological aspects observed in 5 cases of endocarditis due to C. diphtheriae that occurred outside Europe. Four cases occurred in female school-age children (7-14 years) treated at different hospitals in Rio de Janeiro, Brazil. All patients developed other complications including septicemia, renal failure and/or arthritis. Surgical treatment was performed on 2 patients for valve replacement. Lethality was observed in 40% of the cases. Microorganisms isolated from 5 blood samples and identified as C. diphtheriae subsp mitis (N = 4) and C. diphtheriae subsp gravis (N = 1) displayed an aggregative adherence pattern to HEp-2 cells and identical one-dimensional SDS-PAGE protein profiles. Aggregative-adhering invasive strains of C. diphtheriae showed 5 distinct RAPD profiles. Despite the clonal diversity, all 5 C. diphtheriae invasive isolates seemed to display special bacterial adhesive properties that may favor blood-barrier disruption and systemic dissemination of bacteria. In conclusion, blood isolates from patients with endocarditis exhibited a unique adhering pattern, suggesting a pathogenic role of aggregative-adhering C. diphtheriae of different clones in endocarditis. Accordingly, the aggregative-adherence pattern may be used as an indication of some invasive potential of C. diphtheriae strains.

Molecular battles between plant and pathogenic bacteria in the phyllosphere

The phyllosphere, i.e., the aerial parts of the plant, provides one of the most important niches for microbial colonization. This niche supports the survival and, often, proliferation of microbes such as fungi and bacteria with diverse lifestyles including epiphytes, saprophytes, and pathogens. Although most microbes may complete the life cycle on the leaf surface, pathogens must enter the leaf and multiply aggressively in the leaf interior. Natural surface openings, such as stomata, are important entry sites for bacteria. Stomata are known for their vital role in water transpiration and gas exchange between the plant and the environment that is essential for plant growth. Recent studies have shown that stomata can also play an active role in limiting bacterial invasion of both human and plant pathogenic bacteria as part of the plant innate immune system. As counter-defense, plant pathogens such as Pseudomonas syringae pv tomato (Pst) DC3000 use the virulence factor coronatine to suppress stomate-based defense. A novel and crucial early battleground in host-pathogen interaction in the phyllosphere has been discovered with broad implications in the study of bacterial pathogenesis, host immunity, and molecular ecology of bacterial diseases.

Expression and purification of the non-tagged LipL32 of pathogenic Leptospira

Leptospirosis is a reemerging infectious disease and the most disseminated zoonosis worldwide. A leptospiral surface protein, LipL32, only occurs in pathogenic Leptospira, and is the most abundant protein on the bacterial surface, being described as an important factor in host immunogenic response and also in bacterial infection. We describe here an alternative and simple purification protocol for non-tagged recombinant LipL32. The recombinant LipL32(21-272) was expressed in Escherichia coli without His-tag or any other tag used to facilitate recombinant protein purification. The recombinant protein was expressed in the soluble form, and the purification was based on ion exchange (anionic and cationic) and hydrophobic interactions. The final purification yielded 3 mg soluble LipL32(21-272) per liter of the induced culture. Antiserum produced against the recombinant protein was effective to detect native LipL32 from cell extracts of several Leptospira serovars. The purified recombinant LipL32(21-272) produced by this protocol can be used for structural, biochemical and functional studies and avoids the risk of possible interactions and interferences of the tags commonly used as well as the time consuming and almost always inefficient methods to cleave these tags when a tag-free LipL32 is needed. Non-tagged LipL32 may represent an alternative antigen for biochemical studies, for serodiagnosis and for the development of a vaccine against leptospirosis.

Assessment of indicators of vitamin A status in non-cirrhotic chronic hepatitis C patients

Subjects with chronic liver disease are susceptible to hypovitaminosis A due to several factors. Therefore, identifying patients with vitamin deficiency and a requirement for vitamin supplementation is important. Most studies assessing vitamin A in the context of hepatic disorders are conducted using cirrhotic patients. A cross-sectional study was conducted in 43 non-cirrhotic patients with chronic hepatitis C to evaluate markers of vitamin A status represented by serum retinol, liver retinol, and serum retinol-binding protein levels. We also performed the relative dose-response test, which provides an indirect estimate of hepatic vitamin A reserves. These vitamin A indicators were assessed according to the stage of liver fibrosis using the METAVIR score and the body mass index. The sample study was predominantly composed of male subjects (63%) with mild liver fibrosis (F1). The relative dose-response test was <20% in all subjects, indicating vitamin A sufficiency. Overweight or obese patients had higher serum retinol levels than those with a normal body mass index (2.6 and 1.9 µmol/L, respectively; P<0.01). Subjects with moderate liver fibrosis (F2) showed lower levels of serum retinol (1.9 vs 2.5 µmol/L, P=0.01) and retinol-binding protein levels compared with those with mild fibrosis (F1) (46.3 vs 67.7 µg/mL, P<0.01). These results suggested an effect of being overweight on serum retinol levels. Furthermore, more advanced stages of liver fibrosis were related to a decrease in serum vitamin A levels.

Synergistic and antimicrobial properties of commercial turmeric (Curcuma longa) essential oil against pathogenic bacteria

Several studies have shown the antimicrobial and antioxidant properties of turmeric (Curcuma longa), widely used in food industry as a colorant, among other functions. The aim of this study was to determine the antioxidant and antimicrobial properties of turmeric essential oil against pathogenic bacteria and to study the influence of the addition of ascorbic acid on the prevention of polyphenols oxidation. The commercial turmeric essential oil alone did not show bactericidal activity against the microorganisms studied, Listeria monocytogenes and Salmonella typhimurium, but when combined with ascorbic acid, it showed significant antibacterial activity. The highest antimicrobial activity of turmeric essential oil against Salmonella typhimurium was 15.0 ± 1.41 mm at the concentration of 2.30 mg.mL-1 of essential oil and 2.0 mg.mL-1 of ascorbic acid. With regard to Listeria monocytogenes, the largest zone of inhibition (13.7 ± 0.58 mm) was obtained at the same concentrations. The essential oil showed antioxidant activity of EC50 = 2094.172 µg.mL-1 for the DPPH radical scavenging method and 29% under the concentration of 1.667 mg.mL-1 for the β-carotene bleaching method.

Quality indicators and shelf life of red octopus (Octopus maya) in chilling storage

Abstract There are no precedents concerning the quality of Octopus maya during chilled storage. This study evaluated the shelf life of the red octopus in chilling storage (4oC) and the correlation of the sensory quality index with microbiological counting and the biochemical indicators (hypoxanthine, histamine and volatile amines). A total of 112 whole raw octopi (average weight of 896 g) were randomly selected from seven batches and exposed to 4°C for 18, 24, 48, 72, 84, 96, and 100 h. The histamine concentration (91.7%), followed by the counts of psychrotrophic bacteria (5.5%) and hypoxanthine (2.2%), were the predictors from the redundancy analysis that better explained the changes taking place during the chilling hours. After 72 h of chilling, the microbial count was determined to be log 4.7 CFU/g, and the octopus samples were classified as B quality (minor sensory quality defects) based on the sensory quality scale. Although the samples were not classified as unacceptable at 100 h of refrigeration by the sensory index, the level of histamine reached the defect action level (5 mg/100 g) as ruled by the International Food Safety Authorities. The shelf life of the red octopus in chilling storage was predicted to be 119 h.