ORCID Profile
0000-0002-7262-7529
Current Organisation
Griffith University - Gold Coast Campus
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Wiley
Date: 06-2019
DOI: 10.1111/IMJ.14311
Abstract: Diarrhoea that occurs during or after recent travel is predominantly infectious in nature however, in atypical or prolonged cases a broader range of aetiologies for diarrhoea must be considered, and a careful history and examination may reveal clues to more sinister causes of diarrhoea. We report two cases in which a recent travel history and a positive stool culture or polymerase chain reaction testing for bacterial pathogens delayed the diagnosis of ulcerative colitis. As a result of severe inflammatory bowel disease, colectomy was the final result in both cases. Early consideration of causes other than infection for traveller's diarrhoea may prevent unnecessary morbidity in young patients.
Publisher: American Society for Microbiology
Date: 20-10-2020
DOI: 10.1128/AAC.01025-20
Abstract: Achromobacter is a genus of nonfermenting Gram-negative bacteria under order Burkholderiales . Although primarily isolated from respiratory tract of people with cystic fibrosis, Achromobacter spp. can cause a broad range of infections in hosts with other underlying conditions. Their rare occurrence and ever-changing taxonomy hinder defining their clinical features, risk factors for acquisition and adverse outcomes, and optimal treatment. Achromobacter spp.
Publisher: MDPI AG
Date: 20-06-2017
Publisher: Wiley
Date: 08-2023
DOI: 10.1111/IMJ.16198
Abstract: Scedosporium and Lomentospora species are environmental moulds that are virulent in immunocompromised hosts and rarely cause bloodstream infection (BSI). Patients with Scedosporium and Lomentospora species BSI were identified by the state public laboratory service in Queensland, Australia, over a 20‐year period. Twenty‐two incident episodes occurred among 21 residents one patient had a second episode 321 days following the first. Of these, 18 were Lomentospora prolificans , three were Scedosporium apiospermum complex and one was a nonspeciated Scedosporium species. Seventeen (81%) patients died during their index admission, and all‐cause mortality at 30, 90 and 365 days was 73%, 82% and 91% respectively. All 20 patients with haematological malignancy died within 365 days of follow‐up with a median time to death of 9 days (interquartile range, 6–20 days) following diagnoses of BSI.
Publisher: Elsevier BV
Date: 2019
Publisher: Cold Spring Harbor Laboratory
Date: 19-12-2021
DOI: 10.1101/2021.12.12.21266792
Abstract: Antimicrobial resistance (AMR) is an ever-increasing global health concern. One crucial facet in tackling the AMR epidemic is earlier and more accurate AMR diagnosis, particularly in the dangerous and highly multi-drug resistant ESKAPE pathogen, Pseudomonas aeruginosa . We aimed to develop two SYBR Green-based mismatch lification mutation assays (SYBR-MAMAs) targeting GyrA T83I ( gyrA 248), and GyrA D87N, D87Y, and D87H ( gyrA 259). Together, these variants cause the majority of fluoroquinolone (FQ) AMR in P. aeruginosa . Following assay validation, the gyrA 248 and gyrA 259 SYBR-MAMAs were tested on 84 clinical P. aeruginosa isolates from Queensland, Australia, 45 of which demonstrated intermediate/full ciprofloxacin resistance according to antimicrobial susceptibility testing. Our two SYBR-MAMAs correctly predicted an AMR phenotype in the majority (84%) of isolates with intermediate/full FQ resistance. Importantly, all FQ-sensitive strains were predicted to have a sensitive phenotype. Whole-genome sequencing confirmed 100% concordance with SYBR-MAMA genotypes. Our GyrA SYBR-MAMAs provide a rapid and cost-effective method for same-day identification of FQ AMR in P. aeruginosa . An additional SYBR-MAMA targeting the GyrB S466Y/S466F variants would increase FQ AMR prediction to 91%. Clinical implementation of our assays will permit more timely treatment alterations in cases where decreased FQ susceptibility is identified, leading to improved patient outcomes and antimicrobial stewardship.
Publisher: Wiley
Date: 02-2022
DOI: 10.1111/IMJ.15684
Publisher: MDPI AG
Date: 15-04-2017
Publisher: Springer Science and Business Media LLC
Date: 22-04-2021
DOI: 10.1186/S13063-021-05206-8
Abstract: Extended-spectrum beta-lactamase (ESBL) and AmpC-producing Enterobacterales are common causes of bloodstream infection. ESBL-producing bacteria are typically resistant to third-generation cephalosporins and result in a sizeable economic and public health burden. AmpC-producing Enterobacterales may develop third-generation cephalosporin resistance through enzyme hyper-expression. In no observational study has the outcome of treatment of these infections been surpassed by carbapenems. Widespread use of carbapenems may drive the development of carbapenem-resistant Gram-negative bacilli. This study will use a multicentre, parallel group open-label non-inferiority trial design comparing ceftolozane-tazobactam and meropenem in adult patients with bloodstream infection caused by ESBL or AmpC-producing Enterobacterales. Trial recruitment will occur in up to 40 sites in six countries (Australia, Singapore, Italy, Spain, Saudi Arabia and Lebanon). The s le size is determined by a predefined quantity of ceftolozane-tazobactam to be supplied by Merck, Sharpe and Dohme (MSD). We anticipate that a trial with 600 patients contributing to the primary outcome analysis would have 80% power to declare non-inferiority with a 5% non-inferiority margin, assuming a 30-day mortality of 5% in both randomised groups. Once randomised, definitive treatment will be for a minimum of 5 days and a maximum of 14 days with the total duration determined by treating clinicians. Data describing demographic information, risk factors, concomitant antibiotics, illness scores, microbiology, multidrug-resistant organism screening, discharge and mortality will be collected. Participants will have bloodstream infection due to third-generation cephalosporin non-susceptible E. coli and Klebsiella spp. or Enterobacter spp., Citrobacter freundii , Morganella morganii , Providencia spp. or Serratia marcescens . They will be randomised 1:1 to ceftolozane-tazobactam 3 g versus meropenem 1 g, both every 8 h. Secondary outcomes will be a comparison of 14-day all-cause mortality, clinical and microbiological success at day 5, functional bacteraemia score, microbiological relapse, new bloodstream infection, length of hospital stay, serious adverse events, C. difficile infection, multidrug-resistant organism colonisation. The estimated trial completion date is December 2024. The MERINO-3 trial is registered under the US National Institute of Health ClinicalTrials.gov register, reference number: NCT04238390 . Registered on 23 January 2020.
Publisher: Microbiology Society
Date: 27-10-2022
DOI: 10.1099/JMM.0.001593
Abstract: Background. Antimicrobial resistance (AMR) is an ever-increasing global health concern. One crucial facet in tackling the AMR epidemic is earlier and more accurate AMR diagnosis, particularly in the dangerous and highly multi-drug-resistant ESKAPE pathogen, Pseudomonas aeruginosa . Objectives. We aimed to develop two SYBR Green-based mismatch lification mutation assays (SYBR-MAMAs) targeting GyrA T83I ( gyrA 248) and GyrA D87N, D87Y and D87H ( gyrA 259). Together, these variants cause the majority of fluoroquinolone (FQ) AMR in P. aeruginosa . Methods. Following assay validation, the gyrA 248 and gyrA 259 SYBR-MAMAs were tested on 84 Australian clinical P. aeruginosa isolates, 46 of which demonstrated intermediate/full ciprofloxacin resistance according to antimicrobial susceptibility testing. Results. Our two SYBR-MAMAs correctly predicted an AMR phenotype in the majority (83%) of isolates with intermediate/full FQ resistance. All FQ-sensitive strains were predicted to have a sensitive phenotype. Whole-genome sequencing confirmed 100 % concordance with SYBR-MAMA genotypes. Conclusions. Our GyrA SYBR-MAMAs provide a rapid and cost-effective method for same-day identification of FQ AMR in P. aeruginosa . An additional SYBR-MAMA targeting the GyrB S466Y/S466F variants would increase FQ AMR prediction to 91 %. Clinical implementation of our assays will permit more timely treatment alterations in cases where decreased FQ susceptibility is identified, leading to improved patient outcomes and antimicrobial stewardship.
Publisher: American Society of Tropical Medicine and Hygiene
Date: 12-07-2017
Publisher: Oxford University Press (OUP)
Date: 18-11-2020
DOI: 10.1093/CID/CIZ1132
Abstract: Treatment options for multidrug-resistant (MDR) gram-negative infection are growing. However, postregistration, pragmatic, and clinician-led clinical trials in this field are few, recruit small s le sizes, and experience deficiencies in design and operations. MDR gram-negative therapeutic trials are often inefficient, only evaluating a single antibiotic or strategy at a time. Novel clinical trial designs offer potential solutions by attempting to obtain clinically meaningful conclusions at the end or during a trial, for many treatment strategies, simultaneously. An integrated, consensus approach to MDR gram-negative infection trial design is crucial.
Publisher: SAGE Publications
Date: 2021
DOI: 10.1177/20499361211036773
Abstract: Chimeric antigen receptor (CAR) T-cell therapy is a revolutionary treatment modality used to treat haematological malignancies. Lymphocytes are engineered to produce CARs directed towards tumour cell antigens. Clinical trials have demonstrated impressive malignancy-related outcomes. Unfortunately, numerous off-target effects can cause toxicity-related adverse events in this population, the main being cytokine release syndrome and immune effector cell neurotoxicity syndrome. This causes significant patient morbidity and poor outcomes. Patients who receive CAR T-cell therapy are also profoundly immunosuppressed and often cytopenic, which is caused by a multitude of patient- and treatment-related factors. Thus, infection-related complications are also common in this group. Indeed, up to one third of patients will suffer a serious bacterial infection in the first 30 days after therapy. Viral respiratory tract infection appears to be the most common during the late phase and can be severe one patient has died of influenza A infection. Fungal infection and cytomegalovirus (CMV) reactivation appear to be uncommon. Although institutional guidelines on infection-prevention strategies are available, there is a dearth of evidence to support their approach. Future research needs to target important unanswered questions that remain in this patient population in order to improve their short- and long-term outcomes.
Publisher: MDPI AG
Date: 13-10-2021
DOI: 10.3390/PATHOGENS10101319
Abstract: Rickettsia species causing human illness are present globally and can cause significant disease. Diagnosis and identification of this intracellular bacteria are challenging with many available diagnostic modalities suffering from several shortcomings. Detection of antibodies directed against Rickettsia spp. via serological methods remains widely used with a broad range of sensitivity and specificity values reported depending on the assay. Molecular methods, including polymerase chain reaction (PCR) testing, enables species-specific identification with a fast turnaround time however, due to resource requirements, use in some endemic settings is limited. Reports on the use of next-generation sequencing (NGS) and metagenomics to diagnose Rickettsia spp. infection have been increasing. Despite offering several potential advantages in the diagnosis and surveillance of disease, genomic approaches are currently only limited to reference and research laboratories. Continued development of Rickettsia spp. diagnostics is required to improve disease detection and epidemiological surveillance, and to better understand transmission dynamics.
Publisher: Wiley
Date: 16-05-2018
DOI: 10.1111/AJD.12828
Publisher: Oxford University Press (OUP)
Date: 03-05-2023
DOI: 10.1093/OFID/OFAD232
Abstract: Clostridioides difficile infection (CDI) is associated with significant morbidity and mortality in both healthcare and community settings. We aimed to define the predisposing factors, risks for severe disease, and mortality determinants of CDI in eastern Australia over a 1-year period. This is an observational retrospective study of CDI in hospitalized patients aged ≥18 years in 6 tertiary institutions from 1 January 2016 to 31 December 2016. Patients were identified through laboratory databases and medical records of participating institutions. Clinical, imaging, and laboratory data were input into an electronic database hosted at a central site. A total of 578 patients (578 CDI episodes) were included. Median age was 65 (range, 18–99) years and 48.2% were male. Hospital-onset CDI occurred in 64.0%. Recent antimicrobial use (41.9%) and proton pump inhibitor use (35.8%) were common. Significant risk factors for severe CDI were age & years (P & .001), malignancy within the last 5 years (P & .001), and surgery within the previous 30 days (P & .001). Significant risk factors for first recurrence included severe CDI (P = .03) and inflammatory bowel disease (P = .04). Metronidazole was the most common regimen for first episodes of CDI with 65.2% being concordant with Australian treatment guidelines overall. Determinants for death at 60 days included age ≥65 years (P = .01), severe CDI (P & .001), and antibiotic use within the prior 30 days (P = .02). Of those who received metronidazole as first-line therapy, 10.1% died in the 60-day follow-up period, compared to 9.8% of those who received vancomycin (P = .86). Patients who experience CDI are vulnerable and require early diagnosis, clinical surveillance, and effective therapy to prevent complications and improve outcomes.
Publisher: American Society for Microbiology
Date: 11-2018
DOI: 10.1128/AAC.01195-18
Abstract: Carbapenemase-producing Enterobacteriaceae (CPE) contribute significantly to the global public health threat of antimicrobial resistance. OXA-48 and its variants are unique carbapenemases with low-level hydrolytic activity toward carbapenems but no intrinsic activity against expanded-spectrum cephalosporins.
Publisher: Wiley
Date: 06-2021
DOI: 10.1111/IMJ.15356
Publisher: American Society for Microbiology
Date: 03-09-2021
DOI: 10.1128/SPECTRUM.00226-21
Abstract: Carbapenem antibiotics remain the treatment of choice for severe infection due to ESBL- and AmpC-producing Enterobacterales . The use of carbapenems is a major driver of the emergence of carbapenem-resistant Gram-negative bacilli, which are often resistant to most available antimicrobials.
Publisher: Oxford University Press (OUP)
Date: 28-12-2021
Abstract: Extended spectrum β-lactamase (ESBL) and AmpC-producing Gram-negative bacilli contribute significantly to the antimicrobial resistance (AMR) burden worldwide. Temocillin is an intravenous semisynthetic antibiotic that is stable to hydrolysis by ESBLs and AmpC. Temocillin may be a treatment option for serious infections due to these organisms. Third-generation cephalosporin-resistant Escherichia coli and Klebsiella pneumoniae isolates from the MERINO trial were collected. The majority originated from the urinary tract. Isolates had previously undergone whole genome sequencing (WGS) to identify antimicrobial resistance genes. Temocillin minimum inhibitory concentration (MIC) values were determined by broth microdilution (BMD) with a concentration range of 2 to 128 mg/L. A recent EUCAST guideline has recommended clinical breakpoints for urinary E. coli, Klebsiella spp. (except K. aerogenes) and Proteus mirabilis (resistant & mg/L). 317 index bloodstream isolates (275 E. coli and 42 K. pneumoniae) were used. The frequency of β-lactamases among isolates was: CTX-M-15 (56%), OXA-1 (31%), CTX-M-27 (14%), CTX-M-14 (12%) and CMY-2 (8%). Overall, 95% of isolates were susceptible, increased exposure according to EUCAST clinical breakpoints v11.0. Summary MIC values were obtained: MIC50 was 8 mg/L and MIC90 was16 mg/L (range ≤2 to ≥128 mg/L) and did not differ markedly between species. Higher MIC values were seen among isolates that produced more than one β-lactamase but this did not appear to be specific to a single β-lactamase. Temocillin demonstrated favourable in vitro activity against ceftriaxone-resistant Enterobacterales bloodstream isolates and may be a suitable agent to be trialled for treatment of serious infections due to these organisms.
Publisher: Wiley
Date: 10-2021
DOI: 10.1111/IMJ.15516
Publisher: Wiley
Date: 10-2019
DOI: 10.1111/IMJ.14447
Abstract: Coxiella burnetii infection is not known to involve directly the kidneys. Kidney injury associated with Q fever usually manifests in the setting of chronic infection or endocarditis with development of immune complex deposition. Acute kidney injury (AKI) in the context of acute Q fever infection may be more pathologically heterogeneous. We describe two cases of severe AKI secondary to acute Q fever infection, each with marked differences in pathological characteristics, and clinical course.
Publisher: Oxford University Press (OUP)
Date: 22-05-2020
DOI: 10.1093/JAC/DKAA183
Abstract: ESBL-producing Enterobacteriaceae as uropathogens have given rise to a sizeable amount of global morbidity. Community and hospital surveillance studies continue to report increasing proportions of these organisms as causes of urinary tract infection (UTI). Due to limited treatment options and the presence of cross-resistance amongst oral antibiotics of different classes, patients often require IV therapy, thereby increasing healthcare costs and reducing the effectiveness of delivering healthcare. Oral cephalosporin antibiotics are well known for their ability to achieve high urinary concentrations, in addition to achieving clinical success for treatment of uncomplicated UTI with a drug-susceptible pathogen. Novel cephalosporin/β-lactamase inhibitor combinations have been developed and demonstrate good in vitro activity against ESBL-producing isolates. A pooled analysis of in vitro activity of existing oral cephalosporin/clavulanate combinations in ESBL-producing Enterobacteriaceae has shown MIC50s of 0.5–1, 0.125–1 and 0.25 mg/L for cefpodoxime, ceftibuten and cefixime, respectively. A novel cyclic boronic acid β-lactamase inhibitor, QPX7728, was able to produce MIC50 values of 0.5 and ≤0.06 mg/L when paired with cefpodoxime and ceftibuten, respectively. Other novel combinations, cefpodoxime/ETX0282 and ceftibuten/VNRX7145, have also demonstrated excellent activity against ESBL producers. Clinical trials are now awaited.
Publisher: Wiley
Date: 10-2022
DOI: 10.1111/TID.13912
Abstract: Over 1000 solid-organ and close to 2000 stem-cell transplants are performed annually in Australia. Antimicrobial stewardship activities in transplant units in Australia were reviewed. All health service organizations, and thus all transplant centers, in Australia are required to have an antimicrobial stewardship program. Despite this, in one recent survey, 23.5% of hospital antibiotic prescriptions were inappropriate. Vigorous efforts are being made to implement antifungal stewardship in Australian transplant programs, with guidelines for implementation published in December 2021. These guidelines include therapeutic antifungal drug monitoring and diagnostic stewardship as it pertains to the investigation of suspected invasive fungal infections. Infections with multidrug resistant pathogens and invasive fungi are sporadic issues in Australian transplant units, but stewardship efforts can optimize patient outcomes.
Publisher: Wiley
Date: 04-2022
DOI: 10.1111/IMJ.15432
Abstract: COVID‐19 is known to cause an acute respiratory illness, although clinical manifestations outside of the respiratory tract may occur. Early reports have identified SARS‐CoV‐2 as a cause of subacute thyroiditis (SAT). A systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA) guidelines. MEDLINE, Web of Science and PubMed databases were queried in February 2021 for studies from December 2019 to February 2021. MeSH search terms ‘COVID‐19’, ‘SARS‐CoV‐2’ and ‘coronavirus’ along with search terms ‘thyroiditis’, ‘thyrotoxicosis’ and ‘thyroid’ were used. Descriptive statistics for continuous variables and proportions for categorical variables were calculated. Fifteen publications reporting on 17 in idual cases of COVID‐19‐induced SAT were identified. Age ranged from 18 to 69 years. The majority (14 of 17 82%) of cases were female. The delay between onset of respiratory symptoms and diagnosis of SAT ranged from 5 to 49 days (mean, 26.5). Systemic inflammatory response syndrome related to viral infection was uncommonly reported at the time of SAT diagnosis. Thyroid ultrasonography frequently reported an enlarged hypoechoic thyroid with decreased vascularity and heterogenous echotexture. Elevated C‐reactive protein (CRP) was common at the time of SAT diagnosis, with results ranging from 4.5 to 176 mg/L (mean, 41 mg/L). Antithyroid antibodies were frequently negative. SAT‐specific treatment included corticosteroids for 12 of 17 (70.5%) patients. Most returned to normal thyroid status. COVID‐19‐associated SAT may be difficult to identify in a timely manner due to potential absence of classic symptoms, as well as cross‐over of common clinical features between COVID‐19 and thyrotoxicosis.
Publisher: Elsevier BV
Date: 10-2020
Publisher: Wiley
Date: 12-06-2023
DOI: 10.1002/JUM.16286
Abstract: There is a lack of international consensus as to whether high‐ or low‐level disinfection (HLD or LLD) is required for ultrasound (US) transducers used during percutaneous procedures. This study compared the effectiveness of LLD to HLD on US transducers contaminated with microorganisms from skin. Two identical linear US transducers repeatedly underwent either LLD or HLD during the study. Randomization determined which of these transducers was applied to left and right forearms of each participant. Swabs taken from transducers before and after reprocessing were plated then incubated for 4–5 days, after which colony forming units (CFU) were counted and identified. The primary hypothesis was the difference in the proportion of US transducers having no CFUs remaining after LLD and HLD would be less than or equal to the noninferiority margin of −5%. Of the 654 recruited participants 73% (n = 478) had microbial growth from both transducers applied to their left and right forearms before reprocessing. These were included in the paired noninferiority statistical analysis where, after disinfection, all CFUs were eliminated in 100% (95% CI: 99.4–100.0%) of HLD transducer s les (n = 478) and 99.0% (95% CI: 97.6–99.7%) of LLD transducer s les (n = 473). The paired difference in the proportion of transducers having all CFUs eliminated between LLD and HLD was −1.0% (95% CI: −2.4 to −0.2%, P ‐value .001). Disinfection with LLD is noninferior to HLD when microorganisms from skin have contaminated the transducer. Therefore, using LLD for US transducers involved in percutaneous procedures would present no higher infection risk compared with HLD.
Publisher: Elsevier BV
Date: 04-2022
Publisher: Mary Ann Liebert Inc
Date: 12-2015
Abstract: Invasive infections due to carbapenem-resistant Enterobacteriaceae (CRE) are becoming increasingly more prevalent and provide significant morbidity and mortality. Providing curative therapy and overcoming bacterial resistance are difficult tasks with limited antibiotic options. Alternative antibiotics and approaches to therapy are required, with often a compromise in patient outcome. To demonstrate the effective use of therapeutic drug monitoring (TDM) in difficult-to-treat infections due to multiresistant gram-negative bacteria. A case of an elderly woman with an invasive cervical spine infection due to CRE is presented. Her protracted therapeutic course was complicated by multiple treatment failures and severe cervical spine instability. Therapeutic success, as determined by wound healing, cervical spine stability, and continued suppression of inflammatory markers, was obtained by continuous daily ertapenem infusions with TDM guiding the optimal drug dosing. In this unusual setting, TDM was utilized successfully to achieve favorable serum antibiotic concentrations and lead to control of the infection. TDM may be a useful tool in difficult-to-treat infections caused by multiresistant bacteria.
No related grants have been discovered for Adam Stewart.