Overlapping Streptococcus pyogenes and Streptococcus dysgalactiae subspecies equisimilis household transmission and mobile genetic element exchange.

Streptococcus dysgalactiae subspecies equisimilis (SDSE) and Streptococcus pyogenes share skin and throat niches with extensive genomic homology and horizontal gene transfer (HGT) possibly underlying shared disease phenotypes. It is unknown if cross-species transmission interaction occurs. Here, we conduct a genomic analysis of a longitudinal household survey in remote Australian First Nations communities for patterns of cross-species transmission interaction and HGT. Collected from 4547 person-consultations, we analyse 294 SDSE and 315 S. pyogenes genomes. We find SDSE and S. pyogenes transmission intersects extensively among households and show that patterns of co-occurrence and transmission links are consistent with independent transmission without inter-species interference. We identify at least one of three near-identical cross-species mobile genetic elements (MGEs) carrying antimicrobial resistance or streptodornase virulence genes in 55 (19%) SDSE and 23 (7%) S. pyogenes isolates. These findings demonstrate co-circulation of both pathogens and HGT in communities with a high burden of streptococcal disease, supporting a need to integrate SDSE and S. pyogenes surveillance and control efforts.

Inter-species gene flow drives ongoing evolution of Streptococcus pyogenes and Streptococcus dysgalactiae subsp. equisimilis.

Streptococcus dysgalactiae subsp. equisimilis (SDSE) is an emerging cause of human infection with invasive disease incidence and clinical manifestations comparable to the closely related species, Streptococcus pyogenes. Through systematic genomic analyses of 501 disseminated SDSE strains, we demonstrate extensive overlap between the genomes of SDSE and S. pyogenes. More than 75% of core genes are shared between the two species with one third demonstrating evidence of cross-species recombination. Twenty-five percent of mobile genetic element (MGE) clusters and 16 of 55 SDSE MGE insertion regions were shared across species. Assessing potential cross-protection from leading S. pyogenes vaccine candidates on SDSE, 12/34 preclinical vaccine antigen genes were shown to be present in >99% of isolates of both species. Relevant to possible vaccine evasion, six vaccine candidate genes demonstrated evidence of inter-species recombination. These findings demonstrate previously unappreciated levels of genomic overlap between these closely related pathogens with implications for streptococcal pathobiology, disease surveillance and prevention.

Physical distancing and non-respiratory notifiable diseases in the Northern Territory, March-May 2020.

ABSTRACT: Strict physical distancing measures and border controls have been introduced in the Northern Territory (NT), and across Australia, to reduce the spread of coronavirus disease 2019 (COVID-19). These measures have been associated with reduced incidence of other respiratory illnesses such as influenza. It is currently unclear what effect these measures have on non-respiratory communicable diseases. The incidence of notifiable non-respiratory communicable diseases within the NT, from 15 March to 15 May 2020, the period of most restrictive physical distancing, was monitored and is here compared with two control periods: (i) the 4 months immediately prior and (ii) the same two-month period from the preceding 5 years. During the study period, there was a decline in incidence of communicable enteric illnesses, particularly in shigellosis and rotavirus where person-to-person spread is the main transmission route. There was an increase in chlamydial conjunctivitis in areas with endemic trachoma, which is under further investigation. There was no observed increase in conditions associated with crowding, such as those related to group A streptococcal infection.

Clinical syndromes and treatment location predict utility of carbapenem sparing therapies in ceftriaxone-non-susceptible Escherichia coli bloodstream infection.

BACKGROUND: Cefiderocol, ceftazidime-avibactam, ceftolozane-tazobactam, intravenous fosfomycin and plazomicin represent potential carbapenem sparing agents for extended-spectrum-beta-lactamase or AmpC beta-lactamase producing Escherichia coli infection. However, available data is limited in predicting the volume of carbapenem therapy which could be substituted and real-world contraindications. METHODS: We determined the number of carbapenem days of therapy (DOT) which could be substituted and frequent contraindications accounting for antimicrobial susceptibility and site of infection in an unselected cohort with ceftriaxone-non-susceptible E. coli bacteremia at a single health network from 2015 to 2016. Individual patient data was used to calculate DOT and substitution for each agent. RESULTS: There were 108 episodes of E. coli bacteremia resulting in 67.2 carbapenem DOT/100 patient-days of antimicrobial therapy administered. Ceftazidime-avibactam could be used to substitute 36.2 DOT/100 patient-days (54%) for inpatient definitive therapy, ceftolozane-tazobactam for 34.7 DOT/100 patient-days (52%), cefiderocol for 27.1 DOT/100 patient-days (40%), fosfomycin for 23.3 DOT /100 patient-days (35%) and plazomicin for 27.1 DOT/100 patient-days (40%). Non-urinary tract source of infection was the most frequent contraindication to fosfomycin (25), plazomicin (26) and cefiderocol (26). Use in outpatient parenteral antimicrobial therapy (OPAT) programs accounted for 40% of DOT, all of which could be substituted if stability data allowed for ceftazidime-avibactam and ceftolozane-tazobactam. CONCLUSIONS: All tested agents could be used to replace a significant volume of carbapenem therapy. Establishing stability of these agents for use in OPAT is required for maximizing their use as carbapenem sparing agents while randomized clinical data is awaited for some of these agents in resistant E. coli bacteremia.

Epidemiology, treatment and outcomes of bloodstream infection due to vancomycin-resistant enterococci in cancer patients in a vanB endemic setting.

BACKGROUND: Vancomycin-resistant enterococcus (VRE) is an important cause of infection in immunocompromised populations. Few studies have described the characteristics of vanB VRE infection. We sought to describe the epidemiology, treatment and outcomes of VRE bloodstream infections (BSI) in a vanB predominant setting in malignant hematology and oncology patients. METHODS: A retrospective review was performed at two large Australian centres and spanning a 6-year period (2008-2014). Evaluable outcomes were intensive care admission (ICU) within 48 h of BSI, all-cause mortality (7 and 30 days) and length of admission. RESULTS: Overall, 106 BSI episodes were observed in 96 patients, predominantly Enterococcus faecium vanB (105/106, 99%). Antibiotics were administered for a median of 17 days prior to BSI, and 76/96 (79%) were neutropenic at BSI onset. Of patients screened before BSI onset, 49/72 (68%) were found to be colonised. Treatment included teicoplanin (59), linezolid (6), daptomycin (2) and sequential/multiple agents (21). Mortality at 30-days was 31%. On multivariable analysis, teicoplanin was not associated with mortality at 30 days. CONCLUSIONS: VRE BSI in a vanB endemic setting occurred in the context of substantive prior antibiotic use and was associated with high 30-day mortality. Targeted screening identified 68% to be colonised prior to BSI. Teicoplanin therapy was not associated with poorer outcomes and warrants further study for vanB VRE BSI in cancer populations.

When Ventricular Cerebrospinal Fluid Assessment Misleads: Basal Meningitis and the Importance of Lumbar Puncture Sampling.

The diagnosis of central nervous system (CNS) infection relies upon analysis of cerebrospinal fluid (CSF). We present 4 cases of CNS infections associated with basal meningitis and hydrocephalus with normal ventricular CSF but grossly abnormal lumbar CSF. We discuss CSF ventricular-lumbar composition gradients and putative pathophysiological mechanisms and highlight clinical clues for clinicians.

Mycobacterium abscessus bloodstream infection: Unexpected catheter tunnel infection localized by PET/CT.

Mycobacterium abscessus is an emerging cause of invasive infection in the immunosuppressed population. We report a case of M. abscessus bloodstream and catheter tunnel infection localized by positron emission tomography/computer tomography (PET/CT) in an allogeneic haematopoietic stem cell transplant recipient. This case highlights the difficulties in treating invasive M. abscessus infection and the potential role of PET/CT in localizing infection and guiding therapy in this population.

Trends in Tuberculosis Incidence in the Australian-Born in Victoria: Opportunities and Challenges to Elimination.

Australia is a low tuberculosis incidence country. In the setting of increasing migration, we aimed to investigate the epidemiology and trends of tuberculosis in the Australian-born population in the state of Victoria between 1992 and 2017. We performed a retrospective descriptive analysis of demographic, clinical and outcome data extracted from a centralized notifiable disease database. The mean incidence of tuberculosis was 1.19 cases per 100,000 population per year with a small but significant reduction of 0.98% per year. The median age of cases decreased from 67.5 years in 1994 to 17 years in 2017. Among 0⁻14 year-olds, there was an increase from 0.13 cases per 100,000 population in 1996 to 2.15 per 100,000 population in 2017. Data for risk factors were available from 2002 onwards. The most common risk factor in the 0⁻14 year age group was a household contact with tuberculosis (85.1%), followed by having a parent from a high tuberculosis incidence country (70.2%). We found the rate of tuberculosis in the Australian-born population in Victoria is low. However, there has been an increase in incidence in children, particularly among those with links to countries with high tuberculosis incidence. This could threaten progress towards tuberculosis elimination in Australia.

Natural immunity against capsular group X N. meningitidis following an outbreak in Togo, 2007.

BACKGROUND: Capsular group X N. meningitidis (MenX) has emerged as a cause of localized disease outbreaks in sub-Saharan Africa, but the human immune response following exposure to MenX antigens is poorly described. We therefore assessed the natural immunity against MenX in individuals who were living in an area affected by a MenX outbreak during 2007 in Togo, West Africa. During 2009, 300 healthy individuals (100 aged 3-5 years, 100 aged 13-19 years and 100 aged 20-25 years) were included in the study, and serum responses were compared with sera from age-matched controls from the U.K. and Burkina Faso. METHODS: MenX serum bactericidal antibody (SBA) was measured using rabbit complement, and antibodies against MenX polysaccharide (XPS) and outer membrane vesicles (XOMVs) were quantified by ELISA. RESULTS: The proportion of Togolese individuals with an SBA titer of ≥8 against the MenX strain was 29% (95% confidence interval (CI) 18-41) among those aged 3-5 years, 34% (95% CI 9-60) among those aged 13-19 years and 32% (95% CI 24-40) among those aged 20-25 years. These were significantly higher than observed in the control populations from the U.K (range 13-16%) and Burkina Faso (range 2-6%). CONCLUSION: In Togolese individuals, the concentration of serum IgG against XPS was higher among the two older age groups as compared to the youngest age group. Antibody concentrations against MenX PS correlated significantly with SBA titers. This supports further development of a MenX PS based conjugate vaccine. Further studies are needed to verify the ability of MenX PS to induce SBA in humans.

Outcomes of repair of complete atrioventricular septal defect in the current era.

OBJECTIVES: We sought to evaluate the surgical outcomes of the repair of complete atrioventricular septal defects (cAVSDs) in our institution in the current era. METHODS: From 2000 to 2011, 138 patients underwent definitive repair of cAVSD. Repair was performed using a two-patch technique in 92.0% of patients and one-patch technique in 2.2%, and the ventricular septal component was closed directly in 5.8% of patients. RESULTS: Operative mortality was 1.4% (2 of 138). Overall mortality was 5.8% (8 of 138). Follow-up was 96% complete. Freedom from reoperation was 84.3% (95% CI 77.1-91.5%) at 8 years. Age >6 months at repair was associated with higher rates of reoperation (P = 0.001; HR 6.85; 95% CI 2.30-20.44). However, operating at <6 months of age was associated with longer intensive care unit stay (P = 0.019; median 2.7 vs 1.4 days), mechanical ventilation (P = 0.001; median 1.7 vs 0.9 days) and postoperative hospital stay (P = 0.016; median 8 vs 5 days). Moderate or greater left atrioventricular valvular regurgitation (LAVVR) at discharge was a risk factor for reoperation (P < 0.001; HR 10.85; 95% CI 3.75-31.40). CONCLUSIONS: Repair of cAVSD carries low mortality, but a moderate reoperation rate. An optimal time for repair of the cAVSD is between 3 and 6 months of age. Repair prior to 3 months of age and the need for cleft closure were associated with a higher degree of LAVVR at discharge. Greater LAVVR at discharge is a risk factor for reoperation regardless of age at initial repair. In the current era, Down's syndrome is not a risk factor for reoperation.

Emergence of serogroup X meningococcal disease in Africa: need for a vaccine.

Neisseria meningitidis is responsible for the seasonal burden and recurrent epidemics of meningitis in an area of sub-Saharan Africa known as the meningitis belt. Historically, the majority of the cases in the meningitis belt are caused by serogroup A meningococci. Serogroup C meningococci were responsible for outbreaks in the meningitis belt in the 1980s, while serogroup W (formerly W-135) has emerged as a cause of epidemic meningitis since 2000. Serogroup X meningococci have previously been considered a rare cause of sporadic meningitis, but during 2006-2010, outbreaks of serogroup X meningitis occurred in Niger, Uganda, Kenya,Togo and Burkina Faso, the latter with at least 1300 cases of serogroup X meningitis among the 6732 reported annual cases. While serogroup X has not yet caused an epidemic wave of the scale of serogroup A in 1996-1997 or serogroup W in Burkina Faso during 2002, the existing reports suggest a similar seasonal hyperendemicity and capacity for localised epidemics. Serogroup X incidence appears to follow a pattern of highly localised clonal waves, and in affected districts, other meningococcal serogroups are usually absent from disease. Currently, no licensed vaccine is available against serogroup X meningococci. Following the introduction of a monovalent serogroup A conjugate vaccine (MenAfriVac(®)) in the meningitis belt and the upcoming introduction of pneumococcal conjugate vaccines, vaccine-based prevention of serogroup X may become a public health need. The serogroup X polysaccharide capsule is the most likely target for vaccine development, but recent data also indicate a potential role for protein-based vaccines. A multivalent vaccine, preferably formulated as a conjugate vaccine and covering at least serogroups A, W, and X is needed, and the efforts for vaccine development should be intensified.

Characterization of size, structure and purity of serogroup X Neisseria meningitidis polysaccharide, and development of an assay for quantification of human antibodies.

Serogroup X Neisseria meningitidis (MenX) has recently emerged as a cause of localized disease outbreaks in sub-Saharan Africa. In order to prepare for vaccine development, MenX polysaccharide (MenX PS) was purified by standard methods and analyzed for identity and structure by NMR spectroscopy. This study presents the first full assignment of the structure of the MenX PS using (13)C, (1)H and (31)P NMR spectroscopy and total correlation spectroscopy (TOCSY) and (1)H-(13)C heteronuclear single quantum coherence (HSQC). Molecular size distribution analysis using HPLC-SEC with multi-angle laser light scattering (MALLS) found the single peak of MenX PS to have a weight-average molar mass of 247,000g/mol, slightly higher than a reference preparation of purified serogroup C meningococcal polysaccharide. MenX PS tended to be more thermostable than serogroup A PS. A method for the quantification of MenX PS was developed by use of high performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD). A novel and specific ELISA assay for quantification of human anti-MenX PS IgG based on covalent linkage of the MenX PS to functionally modified microtitre plates was developed and found valid for the assessment of the specific antibody concentrations produced in response to MenX vaccination or natural infection. The current work thus provides the necessary background for the development of a MenX PS-based vaccine to prevent meningococcal infection caused by bacteria bearing this capsule.