A role for the enteric nervous system in the response to helminth infections

The enteric nervous system (ENS) in the gut contains a particularly high concentration of nerve cells, and effectively functions as an independent 'minibrain'. Interactions between nerve, endocrine, immune and other cell types allow the sophisticated regulation of normal gut physiology. They can also bring about a co-ordinated response to parasitic infection, possibly leading to expulsion of the parasite. In this review, Derek McKay and Ian Fairweather will consider, in brief, data pertaining to changes in the ENS following intestinal helminth infections and speculate on the role that these alterations may have in the expulsion of the parasite burden and the putative ability of the parasite to modulate these events.

Antimicrobial peptide incorporated poly(2-hydroxyethyl methacrylate) hydrogels for the prevention of Staphylococcus epidermidis-associated biomaterial infections

The effectiveness of the antimicrobial peptide maximin-4, the ultrashort peptide H-Orn-Orn-Trp-Trp-NH(2) , and the lipopeptide C(12) -Orn-Orn-Trp-Trp-NH(2) in preventing adherence of pathogens to a candidate biomaterial were tested utilizing both matrix- and immersion-loaded poly(2-hydroxyethyl methacrylate) (poly(HEMA)) hydrogels. Antiadherent properties correlated to both the concentration released and the relative antimicrobial concentrations of each compound against Staphylococcus epidermidis ATCC 35984, at each time point. Immersion-loaded samples containing C(12) -Orn-Orn-Trp-Trp-NH(2) exhibited the lowest adherence profile for all peptides studied over 1, 4, and 24 h. The results outlined in this article show that antimicrobial peptides have the potential to serve as an important weapon against biomaterial associated infections. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2012.

Nasal immunization with Burkholderia multivorans outer membrane proteins and the mucosal adjuvant adamantylamide dipeptide confers efficient protection against experimental lung infections with B. multivorans and B. cenocepacia

Chronic lung infection by opportunistic pathogens, such as Pseudomonas aeruginosa and members of the Burkholderia cepacia complex, is a major cause of morbidity and mortality in patients with cystic fibrosis. Outer membrane proteins (OMPs) of gram-negative bacteria are promising vaccine antigen candidates. In this study, we evaluated the immunogenicity, protection, and cross-protection conferred by intranasal vaccination of mice with OMPs from B. multivorans plus the mucosal adjuvant adamantylamide dipeptide (AdDP). Robust mucosal and systemic immune responses were stimulated by vaccination of naive animals with OMPs from B. multivorans and B. cenocepacia plus AdDP. Using a mouse model of chronic pulmonary infection, we observed enhanced clearance of B. multivorans from the lungs of vaccinated animals, which correlated with OMP-specific secretory immunoglobulin A responses. Furthermore, OMP-immunized mice showed rapid resolution of the pulmonary infection with virtually no lung pathology after bacterial challenge with B. multivorans. In addition, we demonstrated that administration of B. multivorans OMP vaccine conferred protection against B. cenocepacia challenge in this mouse infection model, suggesting that OMPs provide cross-protection against the B. cepacia complex. Therefore, we concluded that mucosal immunity to B. multivorans elicited by intranasal vaccination with OMPs plus AdDP could prevent early steps of colonization and infection with B. multivorans and also ameliorate lung tissue damage, while eliciting cross-protection against B. cenocepacia. These results support the notion that therapies leading to increased mucosal immunity in the airways may help patients with cystic fibrosis.

Reconstitution of O-specific lipopolysaccharide expression in Burkholderia cenocepacia strain J2315, which is associated with transmissible infections in patients with cystic fibrosis

Burkholderia cenocepacia is an opportunistic bacterium that infects patients with cystic fibrosis. B. cenocepacia strains J2315, K56-2, C5424, and BC7 belong to the ET12 epidemic clone, which is transmissible among patients. We have previously shown that transposon mutants with insertions within the O antigen cluster of strain K56-2 are attenuated for survival in a rat model of lung infection. From the genomic DNA sequence of the O antigen-deficient strain J2315, we have identified an O antigen lipopolysaccharide (LPS) biosynthesis gene cluster that has an IS402 interrupting a predicted glycosyltransferase gene. A comparison with the other clonal isolates revealed that only strain K56-2, which produced O antigen and displayed serum resistance, lacked the insertion element inserted within the putative glycosyltransferase gene. We cloned the uninterrupted gene and additional flanking sequences from K56-2 and conjugated this plasmid into strains J2315, C5424, and BC7. All the exconjugants recovered the ability to form LPS O antigen. We also determined that the structure of the strain K56-2 O antigen repeat, which was absent from the LPS of strain J2315, consisted of a trisaccharide unit made of rhamnose and two N-acetylgalactosamine residues. The complexity of the gene organization of the K56-2 O antigen cluster was also investigated by reverse transcription-PCR, revealing several transcriptional units, one of which also contains genes involved in lipid A-core oligosaccharide biosynthesis.

Clinico-epidemiological features of infections caused by CTX-M type extended spectrum beta lactamase-producing Escherichia coli in hospitalised patients

A review of medical records of 45 of 53 hospitalised patients with positive cultures for CTX-M type ESBL-producing Escherichia coli between 01 January and 31 May 2004 was conducted. The mean age of the population studied was 73.1 (+/-14.6) years and the majority (55.6%) had been under the care of the internal medicine or elderly care service. In the majority (77.8%) of instances the isolate was attributed to a clinical infection rather than colonisation and the commonest clinical specimen to yield the organism was urine, which was positive in 57.8% of patients. Acquisition of the organism was categorised as nosocomial in 68.9% of patients; in this subgroup, the median duration of inpatient stay prior to recovery of the organism was 24 (range 3-240) days. Haemodialysis-dependence was the most common of the comorbidities evaluated. The mean number of antibiotics prescribed per patient in the 30 days prior to first isolation of the organism was 1.7 (range 0-4). Furthermore, the mean number of antibiotic-days exposure per patient during this period was 13.9 (range 0-48). The most frequently received class of antibiotic was beta-lactam/beta-lactamase inhibitor combinations. Of 35 infections, 26 (74.2%) were successfully treated. Overall 12 patients with infection died (34.3%); attributable mortality was presumed in seven (20%).

Trends in the epidemiology of Candida bloodstream infections in Northern Ireland between January 1984 and December 2000

Objective: To describe the epidemiology of Candida bloodstream infections (BSI) in Northern Ireland. Methods: Retrospective collation of data relating to all clinically significant BSI in a university teaching hospital, which had been recorded prospectively, between 1984 and 2000. Results: One hundred and forty five episodes of candidaemia occurred in 144 patients (of mean age 56.6 years). The contribution of Candida spp. towards all significant BSI increased from 2.00% to 2.5%. C. albicans was the most frequently isolated species, however, its incidence fell from 70% to 53% during the study period. The greatest increase in incidence was seen with C. glabrata which was the most common non-albicans species. Twenty-nine per cent of isolates occurred in patients from an intensive care unit and, surprisingly, a further 25.5% occurred in patients from a surgical service. Conclusion: There appears to be several subtle differences in the epidemiology of candidal BSI between Northern Ireland and other countries. © 2002 The British Infection Society.

Comparison of API20C with molecular identification of Candida spp isolated from bloodstream infections

A study was carried out to compare the API20C technology with polymerase chain reaction amplification and direct sequencing of the short internal transcribed spacer region 2 (ITS2) for the identification of 58 isolates of invasive candida species obtained from patients with bloodstream infections over the seven year period 1994 to 2000. Overall, there was only one disagreement between the phenotypic and genotypic identification, where the API scheme identified the isolate as C albicans but the molecular method identified it as C dubliniensis. This study demonstrated that the API20C method is useful in the identification of Candida spp isolated from blood culture and that molecular methods do not enhance identifications made using the API20C scheme. However, for correct reporting of C dubliniensis, an emerging bloodborne pathogen, it is recommended that all isolates identified as C albicans by the API20C scheme are further examined phenotypically and/or genotypically.

Zoonotic helminth infections with particular emphasis on fasciolosis and other trematodiases

Zoonotic infections are among the most common on earth and are responsible for >60 per cent of all human infectious diseases. Some of the most important and well-known human zoonoses are caused by worm or helminth parasites, including species of nematodes (trichinellosis), cestodes (cysticercosis, echinococcosis) and trematodes (schistosomiasis). However, along with social, epidemiological and environmental changes, together with improvements in our ability to diagnose helminth infections, several neglected parasite species are now fast-becoming recognized as important zoonotic diseases of humans, e.g. anasakiasis, several fish-borne trematodiasis and fasciolosis. In the present review, we discuss the current disease status of these primary helminth zoonotic infections with particular emphasis on their diagnosis and control. Advances in molecular biology, proteomics and the release of helminth genome-sequencing project data are revolutionizing parasitology research. The use of these powerful experimental approaches, and their potential benefits to helminth biology are also discussed in relation to the future control of helminth infections of animals and humans.

Characterization of the six glycosyltransferases involved in the biosynthesis of Yersinia enterocolitica serotype O:3 lipopolysaccharide outer core

Yersinia enterocolitica (Ye) is a gram-negative bacterium; Ye serotype O:3 expresses lipopolysaccharide (LPS) with a hexasaccharide branch known as the outer core (OC). The OC is important for the resistance of the bacterium to cationic antimicrobial peptides and also functions as a receptor for bacteriophage phiR1-37 and enterocoliticin. The biosynthesis of the OC hexasaccharide is directed by the OC gene cluster that contains nine genes (wzx, wbcKLMNOPQ, and gne). In this study, we inactivated the six OC genes predicted to encode glycosyltransferases (GTase) one by one by nonpolar mutations to assign functions to their gene products. The mutants expressed no OC or truncated OC oligosaccharides of different lengths. The truncated OC oligosaccharides revealed that the minimum structural requirements for the interactions of OC with bacteriophage phiR1-37, enterocoliticin, and OC-specific monoclonal antibody 2B5 were different. Furthermore, using chemical and structural analyses of the mutant LPSs, we could assign specific functions to all six GTases and also revealed the exact order in which the transferases build the hexasaccharide. Comparative modeling of the catalytic sites of glucosyltransferases WbcK and WbcL followed by site-directed mutagenesis allowed us to identify Asp-182 and Glu-181, respectively, as catalytic base residues of these two GTases. In general, conclusive evidence for specific GTase functions have been rare due to difficulties in accessibility of the appropriate donors and acceptors; however, in this work we were able to utilize the structural analysis of LPS to get direct experimental evidence for five different GTase specificities.

Role of lipid A acylation in Yersinia enterocolitica virulence

Yersinia enterocolitica is an important human pathogen. Y. enterocolitica must adapt to the host environment, and temperature is an important cue regulating the expression of most Yersinia virulence factors. Here, we report that Y. enterocolitica 8081 serotype O:8 synthesized tetra-acylated lipid A at 37 degrees C but that hexa-acylated lipid A predominated at 21 degrees C. By mass spectrometry and genetic methods, we have shown that the Y. enterocolitica msbB, htrB, and lpxP homologues encode the acyltransferases responsible for the addition of C(12), C(14) and C(16:1), respectively, to lipid A. The expression levels of the acyltransferases were temperature regulated. Levels of expression of msbB and lpxP were higher at 21 degrees C than at 37 degrees C, whereas the level of expression of htrB was higher at 37 degrees C. At 21 degrees C, an lpxP mutant was the strain most susceptible to polymyxin B, whereas at 37 degrees C, an htrB mutant was the most susceptible. We present evidence that the lipid A acylation status affects the expression of Yersinia virulence factors. Thus, expression of flhDC, the flagellar master regulatory operon, was downregulated in msbB and lpxP mutants, with a concomitant decrease in motility. Expression of the phospholipase yplA was also downregulated in both mutants. inv expression was downregulated in msbB and htrB mutants, and consistent with this finding, invasion of HeLa cells was diminished. However, the expression of rovA, the positive regulator of inv, was not affected in the mutants. The levels of pYV-encoded virulence factors Yops and YadA in the acyltransferase mutants were not affected. Finally, we show that only the htrB mutant was attenuated in vivo.

Characterization and biological role of the O-polysaccharide gene cluster of Yersinia enterocolitica serotype O:9

Yersinia enterocolitica serotype O:9 is a gram-negative enteropathogen that infects animals and humans. The role of lipopolysaccharide (LPS) in Y. enterocolitica O:9 pathogenesis, however, remains unclear. The O:9 LPS consists of lipid A to which is linked the inner core oligosaccharide, serving as an attachment site for both the outer core (OC) hexasaccharide and the O-polysaccharide (OPS; a homopolymer of N-formylperosamine). In this work, we cloned the OPS gene cluster of O:9 and identified 12 genes organized into four operons upstream of the gnd gene. Ten genes were predicted to encode glycosyltransferases, the ATP-binding cassette polysaccharide translocators, or enzymes required for the biosynthesis of GDP-N-formylperosamine. The two remaining genes within the OPS gene cluster, galF and galU, were not ascribed a clear function in OPS biosynthesis; however, the latter gene appeared to be essential for O:9. The biological functions of O:9 OPS and OC were studied using isogenic mutants lacking one or both of these LPS parts. We showed that OPS and OC confer resistance to human complement and polymyxin B; the OPS effect on polymyxin B resistance could be observed only in the absence of OC.