Biological activity of Burkholderia (Pseudomonas) cepacia lipopolysaccharide

Abstract Burkholderia cepacia has emerged as an important multiresistant pathogen in cystic fibrosis (CF), associated in 20% of colonised patients with a rapid and fatal decline in lung function. Although knowledge of B. cepacia epidemiology has improved, the mechanisms involved in pathogenesis remain obscure. In this study, B. cepacia lipopolysaccharide (LPS) was assessed for endotoxic potential and the capacity to induce tumour necrosis factor (TNF). LPS preparations from clinical and environmental isolates of B. cepacia and from the closely related species Burkholderia gladioli exhibited a higher endotoxic activity and more pronounced cytokine response in vitro compared to preparations from the major CF pathogen Pseudomonas aeruginosa . This study may help to explain the vicious host immune response observed during pulmonary exacerbations in CF patients colonised by B. cepacia and lead to therapeutic advances in clinical management.     

The uptake of choline by Streptococcus pneumoniae.

Uptake of choline, a structural component of pneumococcal C- and F-teichoic acids, into bacteria growing in a defined medium was very efficient with an uptake constant ([S]10 5) of 3.2 microns. It was inhibited by iodoacetate, dinitrophenol and oligomycin but not by structural analogues of choline. Ethanolamine, however, was transported in the absence of choline but with a reduced affinity ([S]0.5 71.4 microns). The same constitutive system was probably used by both ethanolamine and choline. It is suggested that this system required ATP and probably involved choline kinase.     

Sodium dodecyl sulphate--polyacrylamide gel electrophoresis of cell-surface proteins as an aid to the identification of the Bacteroides fragilis group.

The outer-membrane complexes from 40 strains of Bacteroides, representing eight of the species included in the Bacteroides fragilis group, were released by EDTA treatment. The component polypeptides were examined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis on slab gels. Within a species (biotype) the patterns produced indicated marked similarities in the structures of the surface proteins among the strains examined. The patterns produced by strains belonging to different species, however, showed fewer similarities. An unknown organism could therefore be identified to species level using this technique and a few selected biochemical tests.     

How can malaria rapid diagnostic tests achieve their potential? A qualitative study of a trial at health facilities in Ghana

Malaria is still a major public health problem in Brazil, with approximately 306 000 registered cases in 2009, but it is estimated that in the early 1940s, around six million cases of malaria occurred each year. As a result of the fight against the disease, the number of malaria cases decreased over the years and the smallest numbers of cases to-date were recorded in the 1960s. From the mid-1960s onwards, Brazil underwent a rapid and disorganized settlement process in the Amazon and this migratory movement led to a progressive increase in the number of reported cases. Although the main mosquito vector (Anopheles darlingi) is present in about 80% of the country, currently the incidence of malaria in Brazil is almost exclusively (99,8% of the cases) restricted to the region of the Amazon Basin, where a number of combined factors favors disease transmission and impair the use of standard control procedures. Plasmodium vivax accounts for 83,7% of registered cases, while Plasmodium falciparum is responsible for 16,3% and Plasmodium malariae is seldom observed. Although vivax malaria is thought to cause little mortality, compared to falciparum malaria, it accounts for much of the morbidity and for huge burdens on the prosperity of endemic communities. However, in the last few years a pattern of unusual clinical complications with fatal cases associated with P. vivax have been reported in Brazil and this is a matter of concern for Brazilian malariologists. In addition, the emergence of P. vivax strains resistant to chloroquine in some reports needs to be further investigated. In contrast, asymptomatic infection by P. falciparum and P. vivax has been detected in epidemiological studies in the states of Rondonia and Amazonas, indicating probably a pattern of clinical immunity in both autochthonous and migrant populations. Seropidemiological studies investigating the type of immune responses elicited in naturally-exposed populations to several malaria vaccine candidates in Brazilian populations have also been providing important information on whether immune responses specific to these antigens are generated in natural infections and their immunogenic potential as vaccine candidates. The present difficulties in reducing economic and social risk factors that determine the incidence of malaria in the Amazon Region render impracticable its elimination in the region. As a result, a malaria-integrated control effort - as a joint action on the part of the government and the population - directed towards the elimination or reduction of the risks of death or illness, is the direction adopted by the Brazilian government in the fight against the disease.     

Endotoxic activity of lipopolysaccharides isolated from emergent potential cystic fibrosis pathogens

Improved antimicrobial therapies against the classical spectrum of pathogenic bacteria which colonise the lungs of cystic fibrosis (CF) patients has resulted in improved life expectancy and quality of life. Bacterial species that are resistant to a broad range of antibiotics including Stenotrophomonas maltophilia and Alcaligenes xylosoxidans have now emerged as potential new pathogens to fill the niche. At present, it is unclear from clinical data whether these microbes are commensal or pathogenic. In this study we have quantified the inflammatory potential of lipopolysaccharide (LPS) from eight species of Gram-negative organisms which have been cultured with increasing frequency from CF patients. Inflammatory responses induced by LPS from whole human blood and a human-derived monocyte cell line (THP-1) were assessed. Enzyme-linked immunosorbent assays were used to detect interleukin-6, interleukin-8, and tumour necrosis factor alpha (TNF). A bioassay was also used to assess TNF activity. With the exception of S. maltophilia, LPS extracted from all of the bacteria tested upregulated, by varying degrees, expression of each of the proinflammatory cytokines assayed. This study represents the first comprehensive report of the endotoxic potential of a new wave of microbes which are associated with CF.     

Effect of modification of histidine residues on organization of the pigment--protein complexes of chromatium minutissimum

The effect of diethyl pyrocarbonate on chromatophores and isolated pigment--protein complexes of Chromatium minutissimum was studied. It is shown that modification of histidine residues results in the destruction of the core antenna LHI (B880) and in a spectral shift from 850 to 830 nm in the peripheral antenna LHII (B800-850). In the purple sulfur bacterium Chromatium minutissimum the pigment--protein complexes B800-B850 (peripheral antenna, LHII) and B880 (core antenna, LHI) collect and transmit the absorbed light energy to the reaction centers. The composition of pigments and proteins as well as primary structure of the majority of polypeptides in both types of complexes from various photosynthetic bacteria have been determined.     

Clostridium difficile in association with sporadic diarrhoea.

A total of 154 patients admitted to an infectious diseases unit were included in a year''s prospective survey of sporadic diarrhoeal disease. Stools from 19 of them yielded Clostridium difficile, generally on more than one occasion. Twelve of these patients were assessed as having a severe or moderately severe gastrointestinal illness: Cl difficile was the only pathogen isolated from 10 of them, and two had an associated salmonella infection. Seven had had a recent course of antibiotics, but five had not taken antibiotics. Faeces from seven patients with moderate or mild gastrointestinal illness yielded Cl difficile, and two of these patients also had an associated salmonella infection. Two patients in this group had no antibiotic history. From these findings, the occurrence of C difficile in faeces could not be described as antibiotic-associated. Faecal Cl difficile cytotoxin was detected in only six patients, and generally at low levels. In such patients a more relevant pathogenic index might take account of the numbers of Cl difficile present and of their toxigenic potential.     

Assessment of the association between the frequency of micronucleus and p16INK4a/Ki-67 co-expression in patients with cervical intraepithelial lesions

Human papilloma virus (HPV) infection is the main etiological factor for cervical intraepithelial lesions (CIN). An important characteristic of this process is the loss of genome stability. Therefore, it is imperative to use biomarkers of DNA damage caused by genomic instability to identify high risk individuals. We investigated the frequency of micronuclei (MN) in peripheral blood lymphocytes (PBL) of 20 patients, diagnosed as histologically CIN 1 and 10 healthy controls. We also examined the frequency of other nuclear anomalies including nucleoplasmic bridges (NPBs) and nuclear buds (NBUDs) in PBL of patients with CIN 1 and healthy controls, and evaluated the benefits of p16^INK4a and Ki-67 (p16^INK4a/Ki-67) immunohistochemical double staining for identifying cervical squamous cells that express HPV E6/E7 oncogenes. We analyzed the association between the frequency of MN in PBL and the amount of p16^INK4a/Ki-67 co-expression in CIN 1 patients to establish genomic instability. Among CIN 1 subjects, 15% exhibited diffuse p16^INK4a/Ki-67 co-expression and were considered high positive, 25% of the CIN 1 cases exhibited p16^INK4a/Ki-67 co-expression restricted to the lower part of the epithelium and were considered low positive and the remaining 60% of cases were negative. The frequency of MN, NPBs and NBUDs differed significantly among groups. We found a statistically significant positive correlation between p16^INK4a/Ki-67 co-expression and the frequency of MN, NPBs and NBUDs in PBL. Our findings demonstrate the efficacy of p16^INK4a/Ki-67 double immunostaining for histological samples with CIN 1. MN frequency in PBL might be useful for detecting genomic instability in cases of HPV infection and CIN.