Use of Animal Models To Support Revising Meningococcal Breakpoints of β-Lactams

Antimicrobial Susceptibility Survey of Invasive Neisseria meningitidis, United States 2012-2016

BACKGROUND

Historically, antimicrobial resistance has been rare in US invasive meningococcal disease cases.

METHODS

Meningococcal isolates (n = 695) were collected through population-based surveillance, 2012-2016, and national surveillance, 2015-2016. Antimicrobial susceptibility was assessed by broth microdilution. Resistance mechanisms were characterized using whole-genome sequencing.

RESULTS

All isolates were susceptible to 6 antibiotics (cefotaxime, ceftriaxone, meropenem, rifampin, minocycline, and azithromycin). Approximately 25% were penicillin or ampicillin intermediate; among these, 79% contained mosaic penA gene mutations. Less than 1% of isolates were penicillin, ampicillin, ciprofloxacin, or levofloxacin resistant.

CONCLUSIONS

Penicillin- and ampicillin-intermediate isolates were common, but resistance to clinically relevant antibiotics remained rare.

Antibiotic susceptibility and molecular analysis of invasive Neisseria meningitidis recovered in the Republic of Ireland, 1996 to 2016

This study examined the antimicrobial susceptibility of invasive meningococcal disease (IMD)-associated Neisseria meningitidis recovered in the Republic of Ireland between 1996 and 2016. In total, 1359 isolates representing over one-third of all laboratory-confirmed cases of IMD diagnosed each epidemiological year (EY; July 1-June 30) were analysed. All isolates were susceptible to ciprofloxacin, rifampicin and cefotaxime and 74% and 87% were susceptible to sulphonamide and penicillin, respectively. The proportion of isolates exhibiting reduced susceptibility to penicillin increased significantly during the study with no evidence of major clonal expansion or horizontal spread of a specific penA allele. Greater diversity observed among recently recovered meningococci and specifically among isolates exhibiting reduced penicillin susceptibility contributed to the overall increase in penA allele diversity throughout. The emergence and dissemination of strains with phenotypic and genotypic reduced susceptibility to penicillin increase the need for continued surveillance of antimicrobial susceptibility of meningococci in the Republic of Ireland especially in view of the recommendation of penicillin G as empiric treatment of choice for pre-hospital management.

Genomic analysis of the meningococcal ST-4821 complex-Western clade, potential sexual transmission and predicted antibiotic susceptibility and vaccine coverage

INTRODUCTION

The ST-4821 complex (cc4821) is a leading cause of serogroup C and serogroup B invasive meningococcal disease in China where diverse strains in two phylogenetic groups (groups 1 and 2) have acquired fluoroquinolone resistance. cc4821 was recently prevalent among carriage isolates in men who have sex with men in New York City (USA). Genome-level population studies have thus far been limited to Chinese isolates. The aim of the present study was to build upon these with an extended panel of international cc4821 isolates.

METHODS

Genomes of isolates from Asia (1972 to 2017), Europe (2011 to 2018), North America (2007), and South America (2014) were sequenced or obtained from the PubMLST Neisseria database. Core genome comparisons were performed in PubMLST.

RESULTS

Four lineages were identified. Western isolates formed a distinct, mainly serogroup B sublineage with alleles associated with fluoroquinolone susceptibility (MIC <0.03 mg/L) and reduced penicillin susceptibility (MIC 0.094 to 1 mg/L). A third of these were from anogenital sites in men who have sex with men and had unique denitrification gene alleles. Generally 4CMenB vaccine strain coverage was reliant on strain-specific NHBA peptides.

DISCUSSION

The previously identified cc4821 group 2 was resolved into three separate lineages. Clustering of western isolates was surprising given the overall diversity of cc4821. Possible association of this cluster with the anogenital niche is worthy of monitoring given concerns surrounding antibiotic resistance and potential subcapsular vaccine escape.

Evidence for Multi-Organ Infection During Experimental Meningococcal Sepsis due to ST-11 Isolates in Human Transferrin-Transgenic Mice

The description of invasive meningococcal disease that is provoked by Neisseria meningitidis (Nm) is frequently restricted to meningitis. However, a wide panel of clinical presentations can be encountered including severe forms with intense inflammatory reaction leading to multi-organ failure. Several human factors are involved in the development of invasive infections such as transferrin, factor H or CEACAM1. In this study, we used an experimental meningococcal infection in transgenic mice expressing the human transferrin to show multi-organ infection. Mice were infected by an intraperitoneal injection of bacterial suspension (1.5 × 10⁷ colony-forming unit/mouse) of a bioluminescent serogroup C strain belonging to the clonal complex ST-11. Dynamic imaging and histological analysis were performed. The results showed invasion of tissues by Nm with bacteria observed, outside blood vessels, in the kidneys, the heart and the brain as well as skin involvement. These data further support the systemic aspect of invasive meningococcal disease with involvement of several organs including skin as in humans. Thus, our model can be used to study severe forms of meningococcal invasive infections with multi-organ failure.

Geographically widespread invasive meningococcal disease caused by a ciprofloxacin resistant non-groupable strain of the ST-175 clonal complex

INTRODUCTION

Invasive meningococcal disease (IMD) caused by non-serogroupable (NG) strains mainly affects immunocompromised individuals. Reduced susceptibility to penicillin in meningococci is increasing in Europe but ciprofloxacin resistance remains rare. In 2019, three travel-related meningococcal disease cases caused by a ciprofloxacin-resistant NG strain were identified in England, leading Germany to report four additional IMD cases (2016 to 2019). We describe these and newly identified cases and characterise the strain responsible.

METHODS

Cases were identified as part of national surveillance and by analysing available genomes using PubMLST tools.

RESULTS

Of the cases identified in England in 2019, two geographically distinct cases developed conjunctivitis after returning from Mecca (Kingdom of Saudi Arabia) and a third linked case presented with IMD. Of the four cases from Germany, three occurred in asylum seekers - two familial and a further geographically distinct case. Further IMD cases were identified in Italy (n = 2; 2017-2018), Sweden (n = 1; 2016) and England (n = 1; 2015). A single ST-175 clonal complex (cc175) strain with genosubtype P1.22-11,15-25 was responsible. Decreased susceptibility to penicillin was widespread with three ciprofloxacin resistant subclusters. Constituent isolates were potentially covered by subcapsular vaccines.

CONCLUSION

This disease associated NG cc175 strain exhibits resistance to antibiotics commonly used to prevent IMD but is potentially covered by subcapsular (meningococcal B) vaccines.

Bulgecin A: The Key to a Broad-Spectrum Inhibitor That Targets Lytic Transglycosylases

Lytic transglycosylases (Lts) are involved in recycling, cell division, and metabolism of the peptidoglycan. They have been understudied for their usefulness as potential antibacterial targets due to their high redundancy in Gram-negative bacteria. Bulgecin A is an O-sulphonated glycopeptide that targets primarily soluble lytic tranglycosylases (Slt). It has been shown that bulgecin A increases the efficacy of β-lactams that target penicillin bindings proteins (PBPs). Here, we present the high-resolution crystal structure of LtgA from Neisseria meningitidis strain MC58, a membrane bound homolog of Escherichia coli Slt, in complex with bulgecin A. The LtgA-bulgecin A complex reveals the mechanism of inhibition by bulgecin A at near atomic resolution. We further demonstrate that bulgecin A is not only a potent inhibitor of LtgA, but most importantly, it restores the efficacy of β-lactam antibiotics in strains of N. meningitidis and Neisseria gonorrhoeae that have reduced susceptibility to β-lactams. This is particularly relevant for N. gonorrhoeae where no vaccines are available. This work illustrates how best to target dangerous pathogens using a multiple drug target approach, a new and alternative approach to fighting antibiotic resistance.