Sequencing of Neisseria meningitidis penA gene: the key to success in defining penicillin G breakpoints

Draft Genome Sequence of a Mixed-Serogroup W/Y Invasive Neisseria meningitidis Strain

We report the genome of a Neisseria meningitidis strain (GE-156) that was isolated in Switzerland from a patient diagnosed with bacteremia. The strain belongs to a rare mixed serogroup W/Y and sequence type 11847 (clonal complex 167), as revealed by both routine laboratory examination and genomic sequencing.

Evolutionary changes in antimicrobial resistance of invasive Neisseria meningitidis isolates in Belgium from 2000 to 2010: increasing prevalence of penicillin nonsusceptibility

This study was conducted to evaluate the evolution of the antimicrobial susceptibility of Neisseria meningitidis causing invasive diseases in Belgium in the period of January 2000 to December 2010. A total of 1,933 cases of N. meningitidis from invasive infections were analyzed by antimicrobial susceptibility testing at the Belgian Meningococcal Reference Centre. The majority of strains were susceptible to antibiotics that are currently used for the treatment and prophylaxis of meningococcal disease, but the prevalence of clinical isolates with reduced susceptibility to penicillin increased over the years. The phenotyping, genotyping, and determination of MICs of penicillin G were performed. The systematic shift of the curves toward higher penicillin MICs in the susceptible population indicated that this population became less sensitive to penicillin in this period. A 402-bp DNA fragment in the 3' end of penA was sequenced for the 296 nonsusceptible meningococcal strains isolated between 2000 and 2010 to examine the genetic diversity and evolution of their penA gene. In conclusion, the data obtained in our study support the statement that the position of penicillin G as a first choice in the treatment of invasive meningococcal diseases in Belgium should be reexamined. Despite an important number of isolates displaying a reduced susceptibility to penicillin, at present the expanded-spectrum cephalosporins, such as ceftriaxone, are not affected. The follow-up of the evolutionary changes in antimicrobial resistance has also proved to be essential for the recommendation of an appropriate antimicrobial treatment for invasive meningococcal diseases.

Neisseria meningitidis intermediately resistant to penicillin and causing invasive disease in South Africa in 2001 to 2005

Neisseria meningitidis strains (meningococci) with decreased susceptibility to penicillin (MICs, >0.06 microg/ml) have been reported in several parts of the world, but the prevalence of such isolates in Africa is poorly described. Data from an active national laboratory-based surveillance program from January 2001 through December 2005 were analyzed. A total of 1,897 cases of invasive meningococcal disease were reported, with an average annual incidence of 0.83/100,000 population. Of these cases, 1,381 (73%) had viable isolates available for further testing; 87 (6%) of these isolates tested intermediately resistant to penicillin (Pen(i)). Pen(i) meningococcal isolates were distributed throughout all provinces and age groups, and there was no association with outcome or human immunodeficiency virus infection. The prevalence of Pen(i) was lower in serogroup A (7/295; 2%) than in serogroup B (24/314; 8%), serogroup C (9/117; 8%), serogroup Y (22/248; 9%), or serogroup W135 (25/396; 6%) (P = 0.02). Pulsed-field gel electrophoresis grouped 63/82 Pen(i) isolates into nine clusters, mostly according to serogroup. The clustering of patterns from Pen(i) isolates was not different from that of penicillin-susceptible isolates. Twelve sequence types were identified among 18 isolates arbitrarily selected for multilocus sequence typing. DNA sequence analysis of the penA gene identified 26 different alleles among the Pen(i) isolates. Intermediate penicillin resistance is thus widespread among meningococcal serogroups, has been selected in a variety of lineages, and, to date, does not appear to be associated with increased mortality. This is the first report describing the prevalence and molecular epidemiology of Pen(i) meningococcal isolates from sub-Saharan Africa.

Combined real-time PCR and pyrosequencing strategy for objective, sensitive, specific, and high-throughput identification of reduced susceptibility to penicillins in Neisseria meningitidis

A segment of penA in Neisseria meningitidis strains (n = 127), including two nucleotide sites closely associated to reduced susceptibility to penicillins, was amplified and pyrosequenced. All results were in concordance with Sanger sequencing, and a high correlation between alterations in the two Pen(i)-specific sites and reduced susceptibility to penicillins was identified.

Target gene sequencing to characterize the penicillin G susceptibility of Neisseria meningitidis

Clinical isolates of Neisseria meningitidis with reduced susceptibility to penicillin G (intermediate isolates, Pen(I)) harbor alterations in the penA gene encoding the penicillin binding protein 2 (PBP2). A 402-bp DNA fragment in the 3' half of penA was sequenced from a collection of 1,670 meningococcal clinical isolates from 22 countries that spanned 60 years. Phenotyping, genotyping, and the determination of MICs of penicillin G were also performed. A total of 139 different penA alleles were detected with 38 alleles that were highly related, clustered together in maximum-likelihood analysis and corresponded to the penicillin G-susceptible isolates. The remaining 101 penA alleles were highly diverse, corresponded to different genotypes or phenotypes, and accounted for 38% of isolates, but no clonal expansion was detected. Analysis of the altered alleles that were represented by at least five isolates showed high correlation with the Pen(I) phenotype. The deduced amino acid sequence of the corresponding PBP2 comprised five amino acid residues that were always altered. This correlation was not complete for rare alleles, suggesting that other mechanisms may also be involved in conferring reduced susceptibility to penicillin. Evidence of mosaic structures through events of interspecies recombination was also detected in altered alleles. A new website was created based on the data from this work (http://neisseria.org/nm/typing/penA). These data argue for the use of penA sequencing to identify isolates with reduced susceptibility to penicillin G and as a tool to improve typing of meningococcal isolates, as well as to analyze DNA exchange among Neisseria species.

Detection of resistance to rifampicin and decreased susceptibility to penicillin in Neisseria meningitidis by real-time multiplex polymerase chain reaction assay

In this study, we designed primers and probes for the rpoB gene of Neisseria meningitidis to detect rifampicin-resistant strains in a combined use with primers and probes previously described for penicillin intermediate isolates. The assay was set up in the Light Cycler instrument using the Fluorescence Resonance Energy Transfer platform. The method was applied to N. meningitidis strains and to culture-negative cerebrospinal fluids (CSFs) from patients with meningococcal invasive disease. A spiked CSF was used to determine the sensitivity of the assay.

Antibiotic resistant meningococci in Europe: Any need to act?

Meningococcal disease is a serious and rapidly progressing illness. It is therefore very important to monitor changes in the level of antibiotic susceptibility among clinical isolates. Different aspects such as interpretation of laboratory results, determination of breakpoints predicting treatment failure as well as definition of susceptibility levels in clinical samples using molecular methods are critical points for the surveillance of antibiotic resistance in Neisseria meningitidis. Within the strategic framework outlined by the EU.MenNet project, several objectives were identified to analyze 'The spread of antibiotic resistant meningococci in Europe', including the extent of antimicrobial resistance, its association with particular meningococcal lineages and geographical areas, as well as molecular characterization of the mechanisms involved, particularly in penicillin resistance. A heterogeneous figure for the frequency of intermediate resistance to penicillin appears across Europe. This heterogeneity may reflect different clonal lineages and/or uneven access to antibiotics in each country. In addition, the use of different criteria for the methodology used for definition cannot be avoided. The description of five specific changes associated with intermediate resistance to penicillin also allows the design of PCR-based tools to objectify results and for application in clinical samples.

Resistance testing of meningococci: the recommendations of the European Monitoring Group on Meningococci

One of the most controversial topics concerning Neisseria meningitidis is the definition of antimicrobial resistance. A process of harmonization, promoted by the European Monitoring Group on Meningococci (EMGM), is already in progress. There are several aspects of the MIC definition for meningococcal strains for which a consensus is needed, as follows. (1) What methods can be used? At present, both the Etest and agar dilution methods are recommended by the EMGM. Microdilution, also a recommended method, is not used across Europe. (2) What media produce the most reliable data? The use of Mueller-Hinton medium supplemented with 5% blood is recommended for the MIC determination of N. meningitidis by both Etest and agar dilution method. (3) What is the minimum set of antimicrobial agents to be tested? A minimum set should include rifampicin, ciprofloxacin (or another quinolone), penicillin, ampicillin and ceftriaxone. (4) What are the most suitable breakpoints for definition? There is no widely accepted robust evidence base for the definition of breakpoints. Although progress has been made in achieving a standardized methodology, we are still far from obtaining common breakpoints for antimicrobial resistance definition. These differences will imply inability for building a common epidemiologic figure about drug resistance.

Total variation in the penA gene of Neisseria meningitidis: correlation between susceptibility to beta-lactam antibiotics and penA gene heterogeneity

In recent decades, the prevalence of Neisseria meningitidis isolates with reduced susceptibility to penicillins has increased. The intermediate resistance to penicillin (Pen(i)) for most strains is due mainly to mosaic structures in the penA gene, encoding penicillin-binding protein 2. In this study, susceptibility to beta-lactam antibiotics was determined for 60 Swedish clinical N. meningitidis isolates and 19 reference strains. The penA gene was sequenced and compared to 237 penA sequences from GenBank in order to explore the total identified variation of penA. The divergent mosaic alleles differed by 3% to 24% compared to those of the designated wild-type penA gene. By studying the final 1,143 to 1,149 bp of penA in a sequence alignment, 130 sequence variants were identified. In a 402-bp alignment of the most variable regions, 84 variants were recognized. Good correlation between elevated MICs and the presence of penA mosaic structures was found especially for penicillin G and ampicillin. The Pen(i) isolates comprised an MIC of >0.094 microg/ml for penicillin G and an MIC of >0.064 microg/ml for ampicillin. Ampicillin was the best antibiotic for precise categorization as Pen(s) or Pen(i). In comparison with the wild-type penA sequence, two specific Pen(i) sites were altered in all except two mosaic penA sequences, which were published in GenBank and no MICs of the corresponding isolates were described. In conclusion, monitoring the relationship between penA sequences and MICs to penicillins is crucial for developing fast and objective methods for susceptibility determination. By studying the penA gene, genotypical determination of susceptibility in culture-negative cases can also be accomplished.

Neisseria meningitidis C:2b:P1.2,5 with decreased susceptibility to penicillin isolated from a patient with meningitis and purpura fulminans

This report describes the case of an 18-year-old woman with meningococcal meningitis and purpura fulminans. Cerebrospinal fluid culture revealed Neisseria meningitidis serogroup-serotype-serosubtype C:2b:P1.2,5 as the pathogenic organism. Following treatment with cefotaxime and management of multiple organ failure, the patient survived without sequelae. To the best of our knowledge this report represents the first case of a meningococcal strain with a minimum inhibitory concentration of 1.5 mug/ml for penicillin, without beta-lactamase production, to be documented in France. The prevalence of meningococci with reduced susceptibility to penicillin is increasing. The emergence of such strains might represent a serious problem affecting the empirical antibiotic treatment of meningococcal disease.

Antimicrobial activity of LBM415 (NVP PDF-713) tested against pathogenic Neisseria spp. (Neisseria gonorrhoeae and Neisseria meningitidis)

LBM415 (NVP PDF-713), a novel peptide deformylase inhibitor, was tested by reference methods against 2 collections of pathogenic Neisseria, N. gonorrhoeae (157 strains) and N. meningitidis (100 strains). The collection included strains resistant to penicillin, tetracycline, and fluoroquinolones and were also tested against ceftriaxone, ciprofloxacin, penicillin, and tetracycline. The 50% and 90% minimum inhibitory concentration values for LBM415 were 1 and 2 microg/mL, and 4 and 8 microg/mL for N. meningitidis and N. gonorrhoeae, respectively. All comparison agents were more active than this peptide deformylase inhibitor against this genus.