Changes in serogroup and genotype prevalence among carried meningococci in the United Kingdom during vaccine implementation.

BACKGROUND: Herd immunity is important in the effectiveness of conjugate polysaccharide vaccines against encapsulated bacteria. A large multicenter study investigated the effect of meningococcal serogroup C conjugate vaccine introduction on the meningococcal population. METHODS: Carried meningococci in individuals aged 15-19 years attending education establishments were investigated before and for 2 years after vaccine introduction. Isolates were characterized by multilocus sequence typing, serogroup, and capsular region genotype and changes in phenotypes and genotypes assessed. RESULTS: A total of 8462 meningococci were isolated from 47 765 participants (17.7%). Serogroup prevalence was similar over the 3 years, except for decreases of 80% for serogroup C and 40% for serogroup 29E. Clonal complexes were associated with particular serogroups and their relative proportions fluctuated, with 12 statistically significant changes (6 up, 6 down). The reduction of ST-11 complex serogroup C meningococci was probably due to vaccine introduction. Reasons for a decrease in serogroup 29E ST-254 meningococci (from 1.8% to 0.7%) and an increase in serogroup B ST-213 complex meningococci (from 6.7% to 10.6%) were less clear. CONCLUSIONS: Natural fluctuations in carried meningococcal genotypes and phenotypes a can be affected by the use of conjugate vaccines, and not all of these changes are anticipatable in advance of vaccine introduction

Ultrasound-enhanced latex immunoagglutination and PCR as complementary methods for non-culture-based confirmation of meningococcal disease

Preadmission administration of antibiotics to patients with suspected meningococcal infection has decreased the likelihood of obtaining an isolate and has stimulated development of rapid and reliable non-culture-based diagnostic methods. The sensitivity of the conventional test card latex agglutination test (TCLAT) for detection of capsular polysaccharide has been reported to be suboptimal. In the United Kingdom meningococcal DNA detection by PCR has become readily available and is now used as a first-line investigation. Recently, the performance of latex antigen detection has been markedly improved by ultrasound enhancement. Three tests for laboratory confirmation of meningococcal infection, (i) PCR assays, (ii) TCLAT, and (iii) ultrasound-enhanced latex agglutination test (USELAT), were compared in a retrospective study of 125 specimens (serum, plasma, and cerebrospinal fluid specimens) from 90 patients in whom meningococcal disease was suspected on clinical grounds. Samples were from patients with (i) culture-confirmed meningococcal disease, (ii) culture-negative but PCR-confirmed meningococcal disease, and (iii) clinically suspected but non-laboratory-confirmed meningococcal disease. USELAT was found to be nearly five times more sensitive than TCLAT. Serogroup characterization was obtained by both PCR and USELAT for 44 samples; all results were concordant and agreed with the serogroups determined for the isolates when the serogroups were available. For 12 samples negative by USELAT, the serogroup was determined by PCR; however, for 12 other specimens for which PCR had failed to indicate the serogroup, USELAT gave a result. USELAT is a rapid, low-cost method which can confirm a diagnosis, identify serogroups, and guide appropriate management of meningococcal disease contacts. A complementary non-culture-based confirmation strategy of USELAT for local use supported by a centralized PCR assay service for detection of meningococci would give the benefits of timely information and improved epidemiological data

Exploring the selectivity and engineering potential of an NRPS condensation domain involved in the biosynthesis of the thermophilic siderophore fuscachelin

In nonribosomal peptide synthesis, condensation (C) domains are key catalytic domains that most commonly link carrier protein bound substrates to form peptides or depsipeptides. While adenylation domains have been well characterized due to their role in the selection of monomers and hence as gate keepers in nonribosomal peptide biosynthesis, C-domains have been the subject of debate as they do not have apparent “A-domain like” side chain selectivity for their acceptor substrates. To probe the selectivity and specificity of C-domains, here we report our biochemical and structural characterization of the C3-domain from the biosynthesis of the siderophore fusachelin. Our results show that this C-domain is not broadly flexible for monomers bearing significantly alternated side chains or backbones, which suggests there can be a need to consider C-domain specificity for acceptor substrates when undertaking NRPS engineering

Exploring the selectivity and engineering potential of an NRPS condensation domain involved in the biosynthesis of the thermophilic siderophore fuscachelin

In nonribosomal peptide synthesis, condensation (C) domains are key catalytic domains that most commonly link carrier protein bound substrates to form peptides or depsipeptides. While adenylation domains have been well characterized due to their role in the selection of monomers and hence as gate keepers in nonribosomal peptide biosynthesis, C-domains have been the subject of debate as they do not have apparent “A-domain like” side chain selectivity for their acceptor substrates. To probe the selectivity and specificity of C-domains, here we report our biochemical and structural characterization of the C3-domain from the biosynthesis of the siderophore fusachelin. Our results show that this C-domain is not broadly flexible for monomers bearing significantly alternated side chains or backbones, which suggests there can be a need to consider C-domain specificity for acceptor substrates when undertaking NRPS engineering

Association of a Bacteriophage with Meningococcal Disease in Young Adults

Despite being the agent of life-threatening meningitis, Neisseria meningitidis is usually carried asymptomatically in the nasopharynx of humans and only occasionally causes disease. The genetic bases for virulence have not been entirely elucidated and the search for new virulence factors in this species is hampered by the lack of an animal model representative of the human disease. As an alternative strategy we employ a molecular epidemiological approach to establish a statistical association of a candidate virulence gene with disease in the human population. We examine the distribution of a previously-identified genetic element, a temperate bacteriophage, in 1288 meningococci isolated from cases of disease and asymptomatic carriage. The phage was over-represented in disease isolates from young adults indicating that it may contribute to invasive disease in this age group. Further statistical analysis indicated that between 20% and 45% of the pathogenic potential of the five most common disease-causing meningococcal groups was linked to the presence of the phage. In the absence of an animal model of human disease, this molecular epidemiological approach permitted the estimation of the influence of the candidate virulence factor. Such an approach is particularly valuable in the investigation of exclusively human diseases

Restructuring and repositioning of private accomodation in Primorsko-Goranska county: problems and solutions

The paper presents the results of a research conducted on private accommodation as most common form of accommodation within the tourism offer of Primorsko-Goranska County. The study was conducted in 2008, and the obtained results of the research are analysed in the paper, conclusions made, key problems identified and appropriate measures proposed, with the aim of enhancing the quality of this segment of the tourism industry. The goal of the above mentioned measures’ implementation are quality improvement, repositioning and restructuring of private accommodation and its transformation into small family hotels, boarding houses or apart-hotels

P450-mediated dehydrotyrosine formation during WS9326 biosynthesis proceeds via dehydrogenation of a specific acylated dipeptide substrate

WS9326A is a peptide antibiotic containing a highly unusual N-methyl-E-2-3-dehydrotyrosine (NMet-Dht) residue that is incorporated during peptide assembly on a non-ribosomal peptide synthetase (NRPS). The cytochrome P450 encoded by sas16 (P450Sas) has been shown to be essential for the formation of the alkene moiety in NMet-Dht, but the timing and mechanism of the P450Sas-mediated α,β-dehydrogenation of Dht remained unclear. Here, we show that the substrate of P450Sas is the NRPS-associated peptidyl carrier protein (PCP)-bound dipeptide intermediate (Z)-2-pent-1′-enyl-cinnamoyl-Thr-N-Me-Tyr. We demonstrate that P450Sas-mediated incorporation of the double bond follows N-methylation of the Tyr by the N-methyl transferase domain found within the NRPS, and further that P450Sas appears to be specific for substrates containing the (Z)-2-pent-1′-enyl-cinnamoyl group. A crystal structure of P450Sas reveals differences between P450Sas and other P450s involved in the modification of NRPS-associated substrates, including the substitution of the canonical active site alcohol residue with a phenylalanine (F250), which in turn is critical to P450Sas activity and WS9326A biosynthesis. Together, our results suggest that P450Sas catalyses the direct dehydrogenation of the NRPS-bound dipeptide substrate, thus expanding the repertoire of P450 enzymes that can be used to produce biologically active peptides