Resistance to first-line antibiotic therapy among patients with uncomplicated acute cystitis in Melbourne, Australia: prevalence, predictors and clinical impact.

Background: Australian guidelines recommend trimethoprim or nitrofurantoin as first-line agents for uncomplicated urinary tract infections (UTIs). Laboratory surveillance indicates high rates of trimethoprim resistance among urinary bacterial isolates, but there are scant local clinical data about risk factors and impact of trimethoprim resistance. Objectives: To determine the prevalence, risk factors, mechanism and impact of resistance to first-line antibiotic therapy for uncomplicated UTIs in the community setting. Methods: A prospective observational study from October 2019 to November 2021 in four general practices in Melbourne, Australia. Female adult patients prescribed an antibiotic for suspected or confirmed uncomplicated acute cystitis were eligible. Primary outcome was urine isolates with resistance to trimethoprim and/or nitrofurantoin. Results: We recruited 87 participants across 102 UTI episodes with median (IQR) age of 63 (47-76) years. Escherichia coli was the most common uropathogen cultured (48/62; 77%); 27% (13/48) were resistant to trimethoprim (mediated by a dfrA gene) and none were resistant to nitrofurantoin. Isolates with resistance to a first-line therapy were more common among patients reporting a history of recurrent UTIs [risk ratio (RR): 2.08 (95% CI: 1.24-3.51)] and antibiotic use in the previous 6 months [RR: 1.89 (95% CI: 1.36-2.62)]. Uropathogen resistance to empirical therapy was not associated with worse clinical outcomes. Conclusions: Resistance to trimethoprim is common in uncomplicated UTIs in Australia but may not impact clinical outcomes. Further research is warranted on the appropriateness of trimethoprim as empirical therapy, particularly for patients with antimicrobial resistance risk factors.

Antimicrobial resistance and its detection in Staphylococcus saprophyticus urinary isolates.

The aim of this study was to describe the antibiotic susceptibility of clinical Staphylococcus saprophyticus isolates collected prospectively from urine specimens over a 2-month period from September to October 2022 at a single centre in Melbourne, Australia. Species identification was performed by MALDI-TOF MS. All isolates underwent phenotypic antibiotic susceptibility testing by disc diffusion using European Committee on Antimicrobial Susceptibility Testing (EUCAST) and Clinical and Laboratory Standards Institute (CLSI) guidelines and VITEK2, and mecA polymerase chain reaction. A total of 302 S. saprophyticus isolates from 298 patients were included in this study. Most specimens (91.1%) were referred by community general practitioners from non-hospitalised patients. Antimicrobial resistance to non-ß-lactam antibiotics was uncommon; trimethoprim susceptibility was 97%; trimethoprim/sulfamethoxazole, 98%; nitrofurantoin, 100%; and ciprofloxacin, 100% (100% ciprofloxacin susceptible, increased exposure by EUCAST breakpoints). Methicillin resistance (by mecA detection) was the most common form of urinary antibiotic resistance at 5.6%. VITEK2 susceptibility testing for methicillin resistance had a poor specificity of 61.8% (95% CI 55.8-67.4%) compared to mecA detection. These findings indicate that empiric antibiotic recommendations of trimethoprim, trimethoprim/sulfamethoxazole, and nitrofurantoin for treatment of urinary S. saprophyticus remain appropriate.

Efficacy of a Clinical Decision Rule to Enable Direct Oral Challenge in Patients With Low-Risk Penicillin Allergy: The PALACE Randomized Clinical Trial.

Importance: Fewer than 5% of patients labeled with a penicillin allergy are truly allergic. The standard of care to remove the penicillin allergy label in adults is specialized testing involving prick and intradermal skin testing followed by an oral challenge with penicillin. Skin testing is resource intensive, limits practice to specialist-trained physicians, and restricts the global population who could undergo penicillin allergy delabeling. Objective: To determine whether a direct oral penicillin challenge is noninferior to the standard of care of penicillin skin testing followed by an oral challenge in patients with a low-risk penicillin allergy. Design, Setting, and Participants: This parallel, 2-arm, noninferiority, open-label, multicenter, international randomized clinical trial occurred in 6 specialized centers, 3 in North America (US and Canada) and 3 in Australia, from June 18, 2021, to December 2, 2022. Eligible adults had a PEN-FAST score lower than 3. PEN-FAST is a prospectively derived and internationally validated clinical decision rule that enables point-of-care risk assessment for adults reporting penicillin allergies. Interventions: Patients were randomly assigned to either direct oral challenge with penicillin (intervention arm) or a standard-of-care arm of penicillin skin testing followed by oral challenge with penicillin (control arm). Main Outcome and Measure: The primary outcome was a physician-verified positive immune-mediated oral penicillin challenge within 1 hour postintervention in the intention-to-treat population. Noninferiority was achieved if a 1-sided 95% CI of the risk difference (RD) did not exceed 5 percentage points (pp). Results: A total of 382 adults were randomized, with 377 patients (median [IQR] age, 51 [35-65] years; 247 [65.5%] female) included in the analysis: 187 in the intervention group and 190 in the control group. Most patients had a PEN-FAST score of 0 or 1. The primary outcome occurred in 1 patient (0.5%) in the intervention group and 1 patient (0.5%) in the control group, with an RD of 0.0084 pp (90% CI, -1.22 to 1.24 pp). The 1-sided 95% CI was below the noninferiority margin of 5 pp. In the 5 days following the oral penicillin challenge, 9 immune-mediated adverse events were recorded in the intervention group and 10 in the control group (RD, -0.45 pp; 95% CI, -4.87 to 3.96 pp). No serious adverse events occurred. Conclusions and Relevance: In this randomized clinical trial, direct oral penicillin challenge in patients with a low-risk penicillin allergy was noninferior compared with standard-of-care skin testing followed by oral challenge. In patients with a low-risk history, direct oral penicillin challenge is a safe procedure to facilitate the removal of a penicillin allergy label. Trial Registration: ClinicalTrials.gov Identifier: NCT04454229.

The Who, What, When, and Where of Inpatient Direct Oral Penicillin Challenge-Implications for Health Services Implementation.

Inpatient direct oral challenge programs are increasingly deployed as part of antimicrobial stewardship initiatives to reduce the burden and impacts of penicillin allergy labels on antibiotic prescribing. Using data from a prospective, multicenter cohort inpatient penicillin allergy program, we identify the key targets for delabeling to aid health service implementation.

Penicillin Allergy Delabeling Program: an exploratory economic evaluation in the Australian context.

BACKGROUND: Internationally, clinical and economic advantages of low-risk penicillin delabelling have been explored, supporting changes to healthcare delivery systems where penicillin delabelling is embedded into inpatient usual care. AIMS: To determine if economic advantages of low-risk inpatient penicillin delabelling, described in the international literature, are realised in the Australian context. METHODS: This explorative economic evaluation had prospective patient data collection between January and August 2019, across two Australian health services. Part 1: determine the cost per effectively delabelled patient for Penicillin Allergy Delabeling Program inpatients (PADP cohort) compared with Outpatient Antibiotic Allergy Testing Service outpatients (OAATS cohort). Part 2: a cost analysis to compare hospital costs for inpatients with low-risk penicillin allergy who did (PADP cohort) and did not (usual care cohort) undergo PADP delabelling. RESULTS: Part 1: the PADP (n = 350) and OAATS (n = 27 patients, n = 36 individual visits) cohorts were comparable. In PADP, costs/proportion delabelled was $20.10/0.98, equating to $20.51 per effectively delabelled patient; in OAATS, it was $181.24/0.50, equating to $362. Compared with OAATS, PADP was associated with savings of $341.97 per effectively delabelled patient, indicating the outpatient testing was the dominated strategy, being more costly and less effective. Part 2: the PADP (n = 218) and usual care (n = 32) cohorts were comparable. Significantly favouring the delabelled PADP cohort, the mean difference per patient was -4.41 days (95% confidence interval: -7.64, -1.18) and -$9467.72 (95% confidence interval: -$15 419.98, -$3515.46). CONCLUSIONS: Consistent with international literature, delabelling low-risk penicillin allergies in the inpatient setting had economic advantages in the Australian context. Fully powered economic evaluations are urgently required to consolidate these findings.

Favipiravir in early symptomatic COVID-19, a randomised placebo-controlled trial.

Background: Well tolerated antivirals administered early in the course of COVID-19 infection when the viremia is highest could prevent progression to severe disease. Favipiravir inhibits SARS-CoV-2 viral replication in vitro with evidence of clinical benefit in open label trials. Placebo controlled studies of people with early symptomatic COVID-19 with regular assessments of SARS-CoV-2 viral load can determine if it has an antiviral effect and improves clinical outcomes. Methods: People with PCR-confirmed COVID-19 and 5 days or less of symptoms were randomised 1:1 to favipiravir 1800 mg on day 1, then 800 mg twice daily or matched placebo for 14 days. SARS-CoV-2 viral load was quantitated from second daily self-collected nose-throat swabs while receiving study drug. The primary endpoint was time to virological cure defined as 2 successive swabs negative for SARS-CoV-2 by PCR and secondary outcomes were progression of disease severity, symptom resolution and safety. Findings: Between 31 July 2020 and 19 September 2021, 200 people were enrolled (199 in the community, 1 in hospital) with 190 receiving one or more doses of drug (modified intention to treat [mITT] population). There was no difference in time to virological cure (Log-rank p=0.6 comparing Kaplan Meier curves), progression to hospitalisation (14 favipiravir, 9 placebo; p=0.38), time to symptom resolution (cough, fever, sore throat) and there were no deaths. 51 people related an adverse event that was possibly drug related, but these were evenly distributed (n=24 favipiravir, n=27 placebo). Sensitivity analyses where the definition of virological cure was changed to: a single negative PCR, exclude datapoints based on the presence or absence of human DNA in the swab, a SARS-CoV-2 viral load < 300 copies/mL being considered negative all demonstrated no difference between arms. Interpretation: Favipiravir does not improve the time to virological cure or clinical outcomes and shows no evidence of an antiviral effect when treating early symptomatic COVID-19 infection. Funding: The study was supported in part by grants from the Commonwealth Bank Australia, the Lord Mayor's Charitable Foundation, Melbourne Australia and the Orloff Family Charitable Trust, Melbourne, Australia. JHM is supported by the Medical Research Future Fund, AYP, JT are supported by the Australian National Health and Medical Research Council.

Study protocol: Australasian Registry of Severe Cutaneous Adverse Reactions (AUS-SCAR).

INTRODUCTION: Severe cutaneous adverse reactions (SCAR) are a group of T cell-mediated hypersensitivities associated with significant morbidity, mortality and hospital costs. Clinical phenotypes include Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), drug reaction with eosinophilia and systemic symptoms (DRESS) and acute generalised exanthematous pustulosis (AGEP). In this Australasian, multicentre, prospective registry, we plan to examine the clinical presentation, drug causality, genomic predictors, potential diagnostic approaches, treatments and long-term outcomes of SCAR in Australia and New Zealand. METHODS AND ANALYSIS: Adult and adolescent patients with SCAR including SJS, TEN, DRESS, AGEP and another T cell-mediated hypersensitivity, generalised bullous fixed drug eruption, will be prospectively recruited. A waiver of consent has been granted for some sites to retrospectively include cases which result in early mortality. DNA will be collected for all prospective cases. Blood, blister fluid and skin biopsy sampling is optional and subject to patient consent and site capacity. To develop culprit drug identification and prevention, genomic testing will be performed to confirm human leukocyte antigen (HLA) type and ex vivo testing will be performed via interferon-γ release enzyme linked immunospot assay using collected peripheral blood mononuclear cells. The long-term outcomes of SCAR will be investigated with a 12-month quality of life survey and examination of prescribing and mortality data. ETHICS AND DISSEMINATION: This study was reviewed and approved by the Austin Health Human Research Ethics Committee (HREC/50791/Austin-19). Results will be published in peer-reviewed journals and presented at relevant conferences. TRIAL REGISTRATION NUMBER: Australian New Zealand Clinical Trials Registry (ACTRN12619000241134).

SARS-CoV-2 infection results in immune responses in the respiratory tract and peripheral blood that suggest mechanisms of disease severity.

Respiratory tract infection with SARS-CoV-2 results in varying immunopathology underlying COVID-19. We examine cellular, humoral and cytokine responses covering 382 immune components in longitudinal blood and respiratory samples from hospitalized COVID-19 patients. SARS-CoV-2-specific IgM, IgG, IgA are detected in respiratory tract and blood, however, receptor-binding domain (RBD)-specific IgM and IgG seroconversion is enhanced in respiratory specimens. SARS-CoV-2 neutralization activity in respiratory samples correlates with RBD-specific IgM and IgG levels. Cytokines/chemokines vary between respiratory samples and plasma, indicating that inflammation should be assessed in respiratory specimens to understand immunopathology. IFN-α2 and IL-12p70 in endotracheal aspirate and neutralization in sputum negatively correlate with duration of hospital stay. Diverse immune subsets are detected in respiratory samples, dominated by neutrophils. Importantly, dexamethasone treatment does not affect humoral responses in blood of COVID-19 patients. Our study unveils differential immune responses between respiratory samples and blood, and shows how drug therapy affects immune responses during COVID-19.

Blister fluid as a cellular input for ex vivo diagnostics in drug-induced severe cutaneous adverse reactions improves sensitivity and explores immunopathogenesis.

Background: Drug-induced severe cutaneous adverse reactions (SCARs) are presumed T-cell-mediated hypersensitivities associated with significant morbidity and mortality. Traditional in vivo testing methods, such as patch or intradermal testing, are limited by a lack of standardization and poor sensitivity. Modern approaches to testing include measurement of IFN-γ release from patient PBMCs stimulated with the suspected causative drug. Objective: We sought to improve ex vivo diagnostics for drug-induced SCARs by comparing enzyme-linked immunospot (ELISpot) sensitivities and flow cytometry-based intracellular cytokine staining and determination of the cellular composition of separate samples (PBMCs or blister fluid cells [BFCs]) from the same donor. Methods: ELISpot and flow cytometry analyses of IFN-γ release were performed on donor-matched PBMC and BFC samples from 4 patients with SCARs with distinct drug hypersensitivity. Results: Immune responses to suspected drugs were detected in both the PBMC and BFC samples of 2 donors (donor patient 1 in response to ceftriaxone and case patient 4 in response to oxypurinol), with BFCs eliciting stronger responses. For the other 2 donors, only BFC samples showed a response to meloxicam (case patient 2) or sulfamethoxazole and its 4-nitro metabolite (case patient 3). Consistently, flow cytometry revealed a greater proportion of IFN-γ-secreting cells in the BFCs than in the PBMCs. The BFCs from case patient 3 were also enriched for memory, activation, and/or tissue recruitment markers over the PBMCs. Conclusion: Analysis of BFC samples for drug hypersensitivity diagnostics offers a higher sensitivity for detecting positive responses than does analysis of PBMC samples. This is consistent with recruitment (and enrichment) of cytokine-secreting cells with a memory/activated phenotype into blisters.

Defective Severe Acute Respiratory Syndrome Coronavirus 2 Immune Responses in an Immunocompromised Individual With Prolonged Viral Replication.

We describe severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific immune responses in a patient with lymphoma and recent programmed death 1 (PD-1) inhibitor therapy with late onset of severe coronavirus disease 2019 disease and prolonged SARS-CoV-2 replication, in comparison to age-matched and immunocompromised controls. High levels of HLA-DR+/CD38+ activation, interleukin 6, and interleukin 18 in the absence of B cells and PD-1 expression was observed. SARS-CoV-2-specific antibody responses were absent and SARS-CoV-2-specific T cells were minimally detected. This case highlights challenges in managing immunocompromised hosts who may fail to mount effective virus-specific immune responses.

Staff to staff transmission as a driver of healthcare worker infections with COVID-19.

BACKGROUND: High rates of healthcare worker (HCW) infections due to COVID-19 have been attributed to several factors, including inadequate personal protective equipment (PPE), exposure to a high density of patients with COVID-19, and poor building ventilation. We investigated an increase in the number of staff COVID-19 infections at our hospital to determine the factors contributing to infection and to implement the interventions required to prevent subsequent infections. METHODS: We conducted a single-centre retrospective cohort study of staff working at a tertiary referral hospital who tested positive for SARS-CoV-2 between 25 January 2020 and 25 November 2020. The primary outcome was the source of COVID-19 infection. RESULTS: Of 45 staff who returned a positive test result for SARS-CoV-2, 19 were determined to be acquired at our hospital. Fifteen (15/19; 79% [95% CI: 54-94%]) of these were identified through contact tracing and testing following exposures to other infected staff and were presumed to be staff-to-staff transmission, including an outbreak in 10 healthcare workers (HCWs) linked to a single ward that cared for COVID-19 patients. The staff tearoom was identified as the likely location for transmission, with subsequent reduction in HCW infections and resolution of the outbreak following implementation of enhanced control measures in tearoom facilities. No HCW contacts (0/204; 0% [95% CI: 0-2%]) developed COVID-19 infection following exposure to unrecognised patients with COVID-19. CONCLUSION: Unrecognised infections among staff may be a significant driver of HCW infections in healthcare settings. Control measures should be implemented to prevent acquisition from other staff as well as patient-staff transmission.

The Role of In Vivo and Ex Vivo Diagnostic Tools in Severe Delayed Immune-Mediated Adverse Antibiotic Drug Reactions.

BACKGROUND: The use of in vivo and ex vivo diagnostic tools for delayed immune-mediated adverse drug reactions is currently ill defined. OBJECTIVE: To determine whether the combination of skin testing and/or IFN-γ enzyme-linked immunoSpot assay (ELISpot) can aid diagnosis of these allergy phenotypes. METHODS: Patients with antibiotic-associated severe delayed immune-mediated adverse drug reaction hypersensitivity, including Stevens-Johnson syndrome and toxic epidermal necrolysis, drug reaction with eosinophilia and systemic symptoms (DRESS), acute generalized exanthematous pustulosis, generalized bullous fixed drug eruption, and severe maculopapular exanthema, were prospectively recruited. In vivo testing was completed to the implicated drug(s), and ex vivo testing was performed with the patient's PBMCs stimulated with the relevant antibiotic concentrations for IFN-γ release ELISpot measurement. RESULTS: Eighty-one patients met the inclusion criteria, with DRESS (42; 51.9%) accounting for most cases. Among the 63 (78%) who had an ELISpot assay performed, 34 (54%) were positive to at least 1 implicated antibiotic (median spot-forming units/million cells, 99.5; interquartile range, 68-187), with glycopeptide being a strong predictor of positivity (adjusted odds ratio, 6.11; 95% CI, 1.74-21.42). In combination (in vivo and ex vivo), 51 (63%) of those tested were positive to an implicated antibiotic. For DRESS and severe maculopapular exanthema associated with penicillins and cephalosporins, this combination confirmed the culprit agent in 11 of the 12 cases and in 6 of 7 for DRESS associated with glycopeptides. CONCLUSIONS: This study demonstrates that using in vivo in combination with ex vivo testing can enhance the diagnostic approach in these severe phenotypes by assisting with the identification of possible culprit antibiotics.