Clonal expansion of new penicillin-resistant clade of neisseria meningitidis serogroup w clonal complex 11, Australia

In Western Australia, Neisseria meningitidis serogroup W clonal complex 11 became the predominant cause of invasive meningococcal disease in 2016. We used core-genome analysis to show emergence of a penicillin-resistant clade that had the penA_253 allele. This new penicillin-resistant clade might affect treatment regimens for this disease

Reversible vancomycin susceptibility within emerging ST1421 Enterococcus faecium strains is associated with rearranged vanA-gene clusters and increased vanA plasmid copy number

Vancomycin variable enterococci (VVE) are van-positive enterococci with a vancomycin-susceptible phenotype (VVE-S) that can convert to a resistant phenotype (VVE-R) and be selected for during vancomycin exposure. VVE-R outbreaks have been reported in Canada and Scandinavian countries. The aim of this study was to examine the presence of VVE in whole genome sequenced (WGS) Australian bacteremia Enterococcus faecium (Efm) isolates collected through the Australian Group on Antimicrobial resistance (AGAR) network. Eight potential VVEAus isolates, all identified as Efm ST1421, were selected based on the presence of vanA and a vancomycin-susceptible phenotype. During vancomycin selection, two potential VVE-S harboring intact vanHAX genes, but lacking the prototypic vanRS and vanZ genes, reverted to a resistant phenotype (VVEAus-R). Spontaneous VVEAus-R reversion occurred at a frequency of 4-6 × 10−8 resistant colonies per parent cell in vitro after 48 h and led to high-level vancomycin and teicoplanin resistance. The S to R reversion was associated with a 44-bp deletion in the vanHAX promoter region and an increased vanA plasmid copy number. The deletion in the vanHAX promoter region enables an alternative constitutive promoter for the expression of vanHAX. Acquisition of vancomycin resistance was associated with a low fitness cost compared with the corresponding VVEAus-S isolate. The relative proportion of VVEAus-R vs. VVEAus-S decreased over time in serial passages without vancomycin selection. Efm ST1421 is one of the predominant VanA-Efm multilocus sequence types found across most regions of Australia, and has also been associated with a major prolonged VVE outbreak in Danish hospitals

Molecular Epidemiology of Penicillin-Susceptible Staphylococcus aureus Bacteremia in Australia and Reliability of Diagnostic Phenotypic Susceptibility Methods to Detect Penicillin Susceptibility

Background: Defined by the emergence of antibiotic resistant strains, Staphylococcus aureus is a priority bacterial species with high antibiotic resistance. However, a rise in the prevalence of penicillin-susceptible S. aureus (PSSA) bloodstream infections has recently been observed worldwide, including in Australia, where the proportion of methicillin-susceptible S. aureus causing bacteremia identified phenotypically as penicillin-susceptible has increased by over 35%, from 17.5% in 2013 to 23.7% in 2020. Objectives: To determine the population structure of PSSA causing community- and hospital-onset bacteremia in Australia and to evaluate routine phenotypic antimicrobial susceptibility methods to reliably confirm penicillin resistance on blaZ-positive S. aureus initially classified as penicillin-susceptible by the Vitek® 2 automated microbiology system. Results: Whole genome sequencing on 470 PSSA collected in the 2020 Australian Group on Antimicrobial Resistance Australian Staphylococcus aureus Sepsis Outcome Programme identified 84 multilocus sequence types (STs), of which 79 (463 isolates) were grouped into 22 clonal complexes (CCs). The dominant CCs included CC5 (31.9%), CC97 (10.2%), CC45 (10.0%), CC15 (8.7%), and CC188 (4.9%). Many of the CCs had multiple STs and spa types and, based on the immune evasion cluster type, isolates within a CC could be classified into different strains harboring a range of virulence and resistance genes. Phylogenetic analyses of the isolates showed most CCs were represented by one clade. The blaZ gene was identified in 45 (9.6%) PSSA. Although multiclonal, approximately 50% of blaZ-positive PSSA were from CC15 and were found to be genetically distant from the blaZ-negative CC15 PSSA. The broth microdilution, Etest® and cefinase, performed poorly; however, when the appearance of the zone edge was considered; as per the EUCAST and CLSI criteria, disc diffusion detected 100% of blaZ-positive PSSA. Conclusions: In Australia, PSSA bacteremia is not caused by the expansion of a single clone. Approximately 10% of S. aureus classified as penicillin-susceptible by the Vitek® 2 harbored blaZ. Consequently, we recommend that confirmation of Vitek® 2 PSSA be performed using an alternative method, such as disc diffusion with careful interpretation of the zone edge

Temporal Changes in BEXSERO® Antigen Sequence Type Associated with Genetic Lineages of Neisseria meningitidis over a 15-Year Period in Western Australia.

Neisseria meningitidis is the causative agent of invasive meningococcal disease (IMD). The BEXSERO® vaccine which is used to prevent serogroup B disease is composed of four sub-capsular protein antigens supplemented with an outer membrane vesicle. Since the sub-capsular protein antigens are variably expressed and antigenically variable amongst meningococcal isolates, vaccine coverage can be estimated by the meningococcal antigen typing system (MATS) which measures the propensity of the strain to be killed by vaccinated sera. Whole genome sequencing (WGS) which identifies the alleles of the antigens that may be recognised by the antibody response could represent, in future, an alternative estimate of coverage. In this study, WGS of 278 meningococcal isolates responsible for 62% of IMD in Western Australia from 2000-2014 were analysed for association of genetic lineage (sequence type [ST], clonal complex [cc]) with BEXSERO® antigen sequence type (BAST) and MATS to predict the annual vaccine coverage. A hyper-endemic period of IMD between 2000-05 was caused by cc41/44 with the major sequence type of ST-146 which was not predicted by MATS or BAST to be covered by the vaccine. An increase in serogroup diversity was observed between 2010-14 with the emergence of cc11 serogroup W in the adolescent population and cc23 serogroup Y in the elderly. BASTs were statistically associated with clonal complex although individual antigens underwent antigenic drift from the major type. BAST and MATS predicted an annual range of 44-91% vaccine coverage. Periods of low vaccine coverage in years post-2005 were not a result of the resurgence of cc41/44:ST-146 but were characterised by increased diversity of clonal complexes expressing BASTs which were not predicted by MATS to be covered by the vaccine. The driving force behind the diversity of the clonal complex and BAST during these periods of low vaccine coverage is unknown, but could be due to immune selection and inter-strain competition with carriage of non-disease causing meningococci

Untersuchungen zur Bedeutung des präpartalen Progesteronentzugs in Hinblick auf die Steuerung der Geburt und die Ablösung der Nachgeburt beim Rind

Beim Rind ist der präpartale Abfall der maternalen Progesteron (P4)-Konzentration Voraussetzung für den Eintritt der Geburt. Der P4-Abfall spiegelt beim Rind primär den Funktionsverlust des Trächtigkeitsgelbkörpers wider. Über die Bedeutung der plazentaren P4-Produktion lagen bisher praktisch keine Informa¬tionen vor. Die Rinder¬plazenta trägt in der Endphase der Gravidität zwar nur minimal zu den maternalen P4-Spiegeln bei, jedoch bildet sie hohe lokale P4-Konzentrationen im Bereich der feto-maternalen Kontakt¬zone. Diese könnten, vermittelt über P4-Rezeptoren (PR) in den maternalen Karunkeln, ein wesentlicher Faktor für die Differenzie¬rung und Funktion der Plazentome sein. Es wurde die Arbeits¬hypothese ent¬wickelt, dass der Entzug hoher lokaler P4-Konzentrationen ein wesentliches Signal für die Vorbereitung eines termin¬gerechten Nachgeburtsabganges darstellt. Entsprechend könnte ein unvollständiges Sistieren der plazentaren P4-Produktion vor der Geburt eine wesentliche Ursache für das Auftreten idiopathischer Nachge-burts¬verhaltungen sein. Zur Überprüfung dieser Hypo¬these wurden drei gravide Kühe am 270. und 271. Graviditätstag mit dem Antigestagen Aglepriston (Ap) behandelt (Gruppe D272+Ap). Dieser PR-Blocker ermöglicht die Ausschaltung aller rezeptor¬vermittelten P4-Wirkungen unabhängig von der P4-Quelle. Als Kontrollen dienten Tiere mit termin¬gerechter spontaner Geburt und termingerechtem Nachgeburts¬abgang (Gruppe Normalgeburt, n = 4, Trächtigkeitsdauer: 280,5 ± 1,7 Tage) sowie unbehan¬delte Tiere mit Schnitt¬entbindung am Tag 272 (Gruppe D272-Ap, n = 3). Die Kühe wurden klinisch überwacht und der Geburtsverlauf dokumentiert. Von allen Tieren wurden Blutproben in regelmäßigen Abständen sowie Plazentome unmittelbar im Anschluss an die Geburt (Gruppen D272+Ap und Normalgeburt) bzw. während der Schnittentbindungen (Gruppe D272-Ap) entnommen. In den Blutproben wurden die Konzentrationen von Progesteron und Östrogenen mittels radioimmuno¬logischer Verfahren und die 13, 14-Di¬hydro-15-Keto-PGF2α (PGFM)-Konzentrationen mittels ELISA gemessen. Als Parameter für die präpartale Umstrukturierung der Plazentome wurde der prozen¬tuale Anteil der Trophoblast-riesenzellen (TGC) an den Trophoblastzellen und die Reduktion des Karunkelepithels erfasst. Weiterhin wurde die Expression von Cyclooxygenase II (Cox II), PR und Glucocorticoidrezeptor (GR) auf Protein- und mRNA-Ebene beurteilt. Die Aglepristonbehandlung führte bei allen drei Kühen zu einer vorzeitigen Terminie¬rung der Gravidität. Erste Geburtsanzeichen traten 46,3 ± 6,0 Stunden nach Be¬handlungsbeginn auf. Es kam zur vollständigen Öffnung der Zervix, eine adäquate Wehentätigkeit setzte jedoch innerhalb der folgenden zwei Stunden nicht ein. So wurde ein manueller Auszug der Kälber durchgeführt. Neben der Öffnung der Zervix wurde durch die Antigestagenbehandlung die Laktogenese induziert. Entge¬gen der eigenen Hypothese wiesen alle drei Kühe der Gruppe D272+Ap, wie die Tiere der Gruppe D272-Ap, eine komplette Nachgeburts¬ver¬haltung auf und die Kälber beider Gruppen waren gleichermaßen prämatur. Die histo¬morphologischen Unter¬suchungen bestätigten, dass durch die Aglepriston¬behand¬lung die präpartale „Plazentareifung“ nicht induziert wurde. So waren, im Gegensatz zur Normalgeburtsgruppe, in den unreifen Plazentomen der Gruppen D272+Ap und D272−Ap weder ein Rück¬gang des relativen Anteils der TGC noch eine Reduktion des Karunkelepithels nach¬weisbar. Überraschenderweise wurde durch die Antigestagenbehandlung die Luteolyse induziert, erkennbar an einem steilen Abfall der P4-Werte vor bzw. während des Auszugs der Kälber. Korrespondierend mit dem Abfall der P4-Konzen¬tra¬tionen wurde bei den Tieren der Gruppe D272+Ap bereits präpartal ein schwacher Anstieg der PGFM-Werte beobachtet. Da bei diesen Tieren, im Gegensatz zur Normal¬geburtsgruppe, keine Aufregulation der plazentaren Cox II-Expression nach¬weisbar war, ist anzunehmen, dass die Antigestagen-induzierte Luteolyse indirekt durch Prostaglandine extraplazentaren, vermutlich endometrialen, Ursprungs aus¬gelöst wurde. Zum Zeitpunkt des Auszugs waren die PGFM-Plasma¬konzentrationen im Vergleich zur Normalgeburtsgruppe jedoch relativ gering (2,14 ± 1,40 ng/ml vs. 8,70 ± 2,20 ng/ml). Somit erklärt vermutlich ein Mangel an uterotonem PGF2α die Wehen¬schwäche bei den Aglepriston-behandelten Tieren. Die Östrogen¬synthese im Trophoblasten sowie die GR- bzw. PR-Expression in den Plazentomen wurden durch das Antigestagen nicht beeinflusst. Insgesamt lassen die Ergebnisse dieser Arbeit darauf schließen, dass nur ein relativ geringer Anteil der geburtsassoziierten Veränderungen direkt durch den präpartalen Progesteronentzug ausgelöst wird, nämlich die Öffnung der Zervix und das Einsetzen der Laktation. Dagegen erfordern andere wesentliche geburtsassoziierte Vorgänge, wie eine adäquate Wehentätigkeit und die Ablö¬sung der Plazenta, offensichtlich primär Signale aus dem fetalen Kompartiment. Die eigenständige Bedeutung der plazentaren P4¬-Produktion bleibt unklar.In cattle the prepartal decline in maternal progesterone (P4) levels is a prerequisite for the onset of parturition. This P4 withdrawal predominantly reflects the loss of luteal function, and virtually no information on the importance of placental P4 production is available. Despite its minimal contribution to maternal P4 levels in late gestation the bovine placenta is capable of producing high P4 levels locally at the feto-maternal interface, which – mediated by progesterone receptors (PR) previously detected in the maternal caruncles – could be an essential factor in placental differentiation and function. Thus, the hypothesis was put forward that a well-timed and complete withdrawal of high local P4 concentrations is a crucial signal for the timely release of the placenta. According to this concept, an incomplete cessation of placental P4 production during the initiation of parturition could be an important factor in the etiology of placental retention. To test for this hypothesis, three cows were treated with the antiprogestin aglepristone (Ap) on days 270 and 271 of gestation to abolish receptor mediated effects of P4 irrespective of its origin (group D272+Ap). As controls, four cows giving spontaneous birth at normal term (280.5 ± 1.7 days, group NT) with timely release of fetal membranes and three cows undergoing cesarean section on day 272 (group D272-Ap) were included into the study. The cows were monitored clinically, and the progress of birth was registered. From all animals, blood samples were taken regularly during the experimental period, and placentomes were removed per vaginam immediately after birth (groups D272+Ap and NT) or during cesarean section (group D272-Ap). In blood samples, con-centrations of P4 and estrogens were measured by radioimmunological methods, and for the measurement of 13, 14-dihydro-15-keto prostaglandin F2α (PGFM)-concentrations a commercial ELISA kit was used. To characterize the prepartal remodeling of placentomal microarchitecture, the percentage of trophoblast giant cells (TGC) relative to the total number of trophoblast cells and the reduction of caruncular epithelium were determined. Moreover, the expression of cyclo-oxygenase II (Cox II), PR and glucocorticoid receptor (GR) was investigated at protein and mRNA level. The application of aglepristone significantly reduced gestational length. First signs of impending parturition occurred 46.3 ± 6.0 hours after the start of treatment, and vaginal exploration confirmed that the cervix was fully open during this time. However, no progress in the expulsion of the calves could be observed during the following two hours, obviously due to insufficient myometrial activity. Consequently the calves were extracted. Besides a complete opening of the cervix, antiprogestin treatment induced the onset of lactation. Inconsistent with the working hypothesis, in all cows of the treatment group a severe retention of fetal membranes was observed. Similar cases of retained fetal membrane were also observed in all D272-Ap cows, and calves of both groups were slightly premature to a similar extent. Consistent with clinical observations histological investigations of placentomes showed that antiprogestin treatment did not induce placental maturation, whereas for the placentomes of NT cows the prepartal decline in TGC numbers and the reduction of caruncular epithelium was confirmed. Surprisingly, antiprogestin treatment induced luteolysis, as a significant decline of progesterone concentrations started before or during the expulsion of the calf. Con¬comitant with the decline in P4 concentrations in D272+Ap cows an increase of PGFM levels became detectable. The fact that, different from NT animals, no up-regu¬lation of placental Cox II was found suggests that the antiprogestin induced luteolysis indirectly stimulated prostaglandin pro¬duction from an extraplacental source, presumably the intercaruncular endometrium. However, at parturition PGFM levels in D272+Ap cows were clearly lower in comparison to NT cows (2.14 ± 1.40 ng/ml vs. 8.70 ± 2.20 ng/ml), which suggests that insufficient myometrial activity observed in antiprogestin treated cows was related to a reduced availability of uterotonic PGF2α. Placental estrogen production and the expression of PR or GR were not affected by antiprogestin treatment. In conclusion, the results demonstrate that only a minor part of the processes related to bovine parturition is directly dependent on P4 withdrawal, in particular the opening of the cervix and the onset of lactation. Moreover, they suggest that other important processes such as adequate myometrial activity and timely release of the placenta are predominantly dependent on signals from the fetal compartment. The importance of placental P4 production in cattle remains unknown

Travel-associated lineages and unique endemic antimicrobial-susceptible lineages of Neisseria gonorrhoeae predominate in Western Australia

In Australia, gonococcal isolates are monitored for antimicrobial susceptibilities. In Western Australia (WA), gonorrhoea notification rates increased by 63 % between 2013 and 2016, with the steepest increase occurring between 2015 and 2016, before stabilizing at this higher baseline between 2017 and 2020. This increased prevalence was associated with antimicrobial-susceptible (AMS) lineages. To understand the provenance of these isolates causing gonorrhoea in WA, whether they were introduced or expanded from endogenous lineages, 741 isolates were collected in 2017 and characterized by both iPLEX typing and whole genome sequencing (WGS). Antibiograms and genocoding of the isolates revealed that AMS isolates were most prevalent in the remote regions, while the urban/rural regions were characterized by antimicrobial-resistant (AMR) isolates. iPLEX typing identified 78 iPLEX genotypes (WA-1 to WA-78) of which 20 accounted for over 88 % of isolates. WA-10 was the most frequently identified genotype in the urban/rural regions whilst WA-29 was the most frequently identified genotype in the remote regions. Genotypes WA-38, WA-52 and WA-13 accounted for 81 % (n=36/44) of the azithromycin-resistant N. gonorrhoeae (AziR) isolates. A representative isolate of each iPLEX genotype and AMR biotype was whole genome sequenced and analysed using MLST, NG-MAST and NG-STAR, and the novel core genome clustering Ng_cgc_400 typing scheme. Five predominant Bayesian population groups (termed BPG-1 to 5) were identified in the study collection. BPG-1 and BPG-2 were associated with AMS isolates from the remote regions. BPG-1 and BPG-2 were shown to be unique to the remote regions based on a minimum spanning tree against 4000 international isolates. AMS isolates in urban/rural regions were dominated by international lineages. AziR and Cef DS (decreased susceptibility to ceftriaxone) was concentrated in three urban/rural genomic groups (BPG-3, 4 and 5). Azithromycin minimum inhibitory concentrations (0.5–16 mg l−1) correlated with the accumulation of mtrR mutations or/and the fraction of 23S rRNA C2611T mutated copies. The majority of isolates in BPG-3, 4 and 5 could be correlated with known AMR lineages circulating globally and nationally. In conclusion, the surge in AMS isolates in WA in 2017 was due to importation of international AMS lineages into urban/rural regions, whilst the local AMS lineages persisted largely in the remote regions. Bridging between the urban/rural and remote regions was relatively rare, but continued surveillance is required to prevent ingress of AMR strains/lineages into the remote regions of WA

Identification and characterisation of fosfomycin resistance in Escherichia coli urinary tract infection isolates from Australia

© 2020 Elsevier Ltd Of 1033 Escherichia coli urinary tract infection isolates collected from females >12 years of age in Australia in 2019, only 2 isolates were resistant to fosfomycin with a minimum inhibitory concentration (MIC) of >256 mg/L. Despite having different multilocus sequence types, the two isolates harboured an identical plasmid-encoded fosA4 gene. The fosA4 gene has previously been identified in a single clinical E. coli isolate cultured in Japan in 2014. Each fosfomycin-resistant isolate harboured two conjugative plasmids that possessed an array of genes conferring resistance to aminoglycosides, β-lactams, macrolides, quinolones, sulfonamides and/or trimethoprim

Attachment and invasion of Neisseria meningitidis to host cells is related to surface hydrophobicity, bacterial cell size and capsule

We compared exemplar strains from two hypervirulent clonal complexes, strain NMB-CDC from ST-8/11 cc and strain MC58 from ST-32/269 cc, in host cell attachment and invasion. Strain NMB-CDC attached to and invaded host cells at a significantly greater frequency than strain MC58. Type IV pili retained the primary role for initial attachment to host cells for both isolates regardless of pilin class and glycosylation pattern. In strain MC58, the serogroup B capsule was the major inhibitory determinant affecting both bacterial attachment to and invasion of host cells. Removal of terminal sialylation of lipooligosaccharide (LOS) in the presence of capsule did not influence rates of attachment or invasion for strain MC58. However, removal of either serogroup B capsule or LOS sialylation in strain NMB-CDC increased bacterial attachment to host cells to the same extent. Although the level of inhibition of attachment by capsule was different between these strains, the regulation of the capsule synthesis locus by the two-component response regulator MisR, and the level of surface capsule determined by flow cytometry were not significantly different. However, the diplococci of strain NMB-CDC were shown to have a 1.89-fold greater surface area than strain MC58 by flow cytometry. It was proposed that the increase in surface area without changing the amount of anchored glycolipid capsule in the outer membrane would result in a sparser capsule and increase surface hydrophobicity. Strain NMB-CDC was shown to be more hydrophobic than strain MC58 using hydrophobicity interaction chromatography and microbial adhesion-to-solvents assays. In conclusion, improved levels of adherence of strain NMB-CDC to cell lines was associated with increased bacterial cell surface and surface hydrophobicity. This study shows that there is diversity in bacterial cell surface area and surface hydrophobicity within N. meningitidis which influence steps in meningococcal pathogenesis

Differences in the population structure of <i>Neisseria meningitidis</i> in two Australian states: Victoria and Western Australia

<div><p><i>Neisseria meningitidis</i> is the causative agent of invasive meningococcal disease (IMD). A recombinant vaccine called Bexsero^® incorporates four subcapsular antigens (fHbp, NHBA, NadA and PorA) which are used to assign a Bexsero^® antigen sequence type (BAST) to each meningococcal strain. The vaccine elicits an immune response against combinations of variants of these antigens which have been grouped into specific BAST profiles that have been shown to have different distributions within geographical locations thus potentially affecting the efficacy of the vaccine. In this study, invasive meningococcal disease isolates from the western seaboard of Australia (Western Australia; WA) were compared to those from the south-eastern seaboard (Victoria; VIC) from 2008 to 2012. Whole-genome sequencing (WGS) of 131 meningococci from VIC and 70 meningococci from WA were analysed for MLST, FetA and BAST profiling. Serogroup B predominated in both jurisdictions and a total of 10 MLST clonal complexes (cc) were shared by both states. Isolates belonging to cc22, cc103 and cc1157 were unique to VIC whilst isolates from cc60 and cc212 were unique to WA. Clonal complex 41/44 represented one-third of the meningococcal population in each state but the predominant ST was locally different: ST-6058 in VIC and ST-146 in WA. Of the 108 BAST profiles identified in this collection, only 9 BASTs were simultaneously observed in both states. A significantly larger proportion of isolates in VIC harboured alleles for the NHBA-2 peptide and fHbp-1, antigenic variants predicted to be covered by the Bexsero^® vaccine. The estimate for vaccine coverage in WA (47.1% [95% CI: 41.1–53.1%]) was significantly lower than that in VIC (66.4% [95% CI: 62.3–70.5%]). In conclusion, the antigenic structure of meningococci causing invasive disease in two geographically distinct states of Australia differed significantly during the study period which may affect vaccine effectiveness and highlights the need for representative surveillance when predicting potential impact of meningococcal B vaccines.</p></div

Serogroup (Panel A) and clonal complex (Panel B) distribution per annum from 2000–2014.

<p>(A) Serogroup was reported for 436 IMD cases. (B) Clonal complex was reported for 278 cultured isolates. The category “Other” indicates clonal complexes with rare frequency (less than 5 isolates) and represents cc8, cc22, cc35, cc60, cc162, cc167, cc212, cc461, cc1157 and no assigned cc.</p