National action plans for antimicrobial resistance and variations in surveillance data platforms

Objective

To assess how national antimicrobial susceptibility data used to inform national action plans vary across surveillance platforms.

Methods

We identified available open-access, supranational, interactive surveillance platforms and cross-checked their data in accordance with the World Health Organization's (WHO's) Data Quality Assurance: module 1. We compared platform usability and completeness of time-matched data on the antimicrobial susceptibilities of four blood isolate species: Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus and Streptococcus pneumoniae from WHO's Global Antimicrobial Resistance and Use Surveillance System, European Centre for Disease Control's (ECDC's) network and Pfizer's Antimicrobial Testing Leadership and Surveillance database. Using Bland-Altman analysis, paired t-tests, and Wilcoxon signed-rank tests, we assessed susceptibility data and number of isolate concordances between platforms.

Findings

Of 71 countries actively submitting data to WHO, 28 also submit to Pfizer's database; 19 to ECDC; and 16 to all three platforms. Limits of agreement between WHO's and Pfizer's platforms for organism-country susceptibility data ranged from -26% to 35%. While mean susceptibilities of WHO's and ECDC's platforms did not differ (bias: 0%, 95% confidence interval: -2 to 2), concordance between organism-country susceptibility was low (limits of agreement -18% to 18%). Significant differences exist in isolate numbers reported between WHO-Pfizer (mean of difference: 674, P-value: < 0.001, and WHO-ECDC (mean of difference: 192, P-value: 0.04) platforms.

Conclusion

The considerable heterogeneity of nationally submitted data to commonly used antimicrobial resistance surveillance platforms compromises their validity, thus undermining local and global antimicrobial resistance strategies. Hence, we need to understand and address surveillance platform variability and its underlying mechanisms.

4 Early identification of high-risk individuals for combination monoclonal antibody therapy is feasible by SARS-CoV-2 anti-spike antibody specific lateral flow assay

Background

Combination monoclonal antibody therapy has recently been approved for prevention and treatment of severe COVID-19 infection in the UK. Available data suggests benefit is limited to those yet to mount an effective immune response from natural infection or vaccination, but concern exists around ability to make timely assessment of immune status of community-based patients.

Methods

Healthcare workers were invited to undergo paired laboratory-based and rapid point-of- care (POC) lateral flow anti-spike antibody testing. Three commercial POC tests were selected to represent currently available testing methods: a split IgM/IgG anti-spike antibody test, an anti-receptor binding domain total antibody test and an anti-spike neutralisation assay. Qualitative POC colourmetric band intensities were independently scored and correlated with quantitative IgG neutralising antibody titres (Abbott Architect SARS-CoV-2 IgG Quant II chemiluminescent microparticle immunoassay [CMIA]). CMIA titres were correlated with the World Health Organisation international reference standard for neutralising antibody. Negative controls were carried out using 2018 pre-pandemic sera and post-pandemic individuals with negative CMIA results (target population).

Results

190 individuals (median 40 years, IQR 29-49; 76.2% female) underwent paired testing, with a further 40 pre-pandemic sera tested. Assays demonstrated high performance characteristics: split IgM/IgG assay sensitivity 96.2% (95%CI 92.4.5–98.5), specificity 100.0% (95%CI 91.8–100.0); anti-receptor binding domain total antibody assay sensitivity 100.0% (95%CI 95.5–100.0), specificity 100.0% (95%CI 69.2–100.0). The neutralising antibody assay had a specificity of 97.0% (95%CI 84.2–99.9%) and strongly correlated with neutralising antibody titre (p<0.001). Probability for matched paired results was significant (McNemar’s p<0.001) while band intensity correlated strongly with neutralising titres (p<0.0001). Positive and negative predictive values for total antibody and neutralising assays were both >99%.

Conclusions

POC assays were found to be reliable predictors of both antibody status and broadly of neutralising antibody titre. Anti-S POC assays have potential to act as suitable alternatives for rapid identification of community patient immune status at presentation.

Early identification of high-risk individuals for monoclonal antibody therapy and prophylaxis is feasible by SARS-CoV-2 anti-spike antibody specific lateral flow assay

Monoclonal antibody therapy has been approved for prophylaxis and treatment of severe COVID-19 infection. Greatest benefit appears limited to those yet to mount an effective immune response from natural infection or vaccination, but concern exists around ability to make timely assessment of immune status of community-based patients where laboratory-based serodiagnostics predominate. Participants were invited to undergo paired laboratory-based (Abbott Architect SARS-CoV-2 IgG Quant II chemiluminescent microparticle immunoassay) and lateral flow assays (LFA; a split SARS-CoV-2 IgM/IgG and total antibody test) able to detect SARS-CoV-2 anti-spike antibodies. LFA band strength was compared with CMIA titer by log-linear regression. Two hundred individuals (median age 43.5 years, IQR 30−59; 60.5% female) underwent testing, with a further 100 control sera tested. Both LFA band strengths correlated strongly with CMIA antibody titers (P < 0.001). LFAs have the potential to assist in early identification of seronegative patients who may demonstrate the greatest benefit from monoclonal antibody treatment.

3 Clinical implications of the differential antibody response in mild-moderate SARS-CoV-2: a prospective multi-centre cross-sectional study

Introduction

Serological testing can augment delayed case identification programmes for Severe Acute Respiratory Syndrome coronoravirus-2 (SARS-CoV-2). Immunoassays employ anti-nucleocapsid (anti-NP; the majority) or potentially neutralising anti-spike (including anti-receptor binding domain; anti-RBD) antibody targets, yet correlation between assays and variability arising from disease symptomatology remains unclear. We explore these possibly differential immune responses across the disease spectrum.

Methods

A multicentre prospective study was undertaken via a SARS-CoV-2 delayed case identification programme (08 May-11 July 2020). Matched samples were tested for anti-NP and anti-RBD (utilising an ‘inhouse’ double-antigen bridged assay), reactivity expressed as test/cut-off binding ratios (BR) and results compared. A multivariate linear regression model analysed age, sex, symptomatology, PCR positivity, anti-NP, and anti-RBD BRs. Participants were followed up for possible reinfection.

Results

902 individuals underwent matched testing; 109 were SARS-CoV-2 PCR swab positive. Anti-NP, anti-RBD immunoassay agreement was 87.5% (95% CI 85.3–89.6), with BRs strongly correlated (R=0.75). PCR confirmed cases were more frequently identified by anti-RBD (sensitivity 108/109, 99.1%, 95% CI 95.0–100.0) than anti-NP (102/109, 93.6%, 95% CI 87.2–97.4). Anti-RBD identified an additional 83/325 (25.5%) cases in those seronegative for anti-NP. Presence of anti-NP (p<0.0001), fever (p=0.005), or anosmia (p=0.002) were all significantly associated with an increased anti-RBD BR. Age was associated with reduced anti-RBD BR (p=0.052). Three cases with evidence of seroconversion (anti-RBD seropositive) presented with subsequent reactive PCR results, two of which coincided with first time onset of Public Heath England SARS-CoV-2 symptoms.

Conclusions

SARS-CoV-2 anti-RBD shows significant correlation with anti-NP for absolute seroconversion, and BRs. Higher BRs are seen in symptomatic individuals with significantly higher levels seen in those with fever and anosmia. The degree of discordant results (12.5%) limits the use of anti-NP as a stand-alone for delayed case finding programmes. Similarly, this discordance limits the utility of non-neutralising anti-NP assays in place of potentially neutralising anti-RBD to infer possible immunity.

** this abstract presentation was awarded an Honourable Mention

Fluorescence Imaging for Cancer Screening and Surveillance

The advent of fluorescence imaging (FI) for cancer cell detection in the field of oncology is promising for both cancer screening and surgical resection. Particularly, FI in cancer screening and surveillance is actively being evaluated in many new clinical trials with over 30 listed on Clinical Trials.gov . While surgical resection forms the foundation of many oncologic treatments, early detection is the cornerstone for improving outcomes and reducing cancer-related morbidity and mortality. The applications of FI are twofold as it can be applied to high-risk patients in addition to those undergoing active surveillance. This technology has the promise of highlighting lesions not readily detected by conventional imaging or physical examination, allowing disease detection at an earlier stage of development. Additionally, there is a persistent need for innovative, cost-effective imaging modalities to ameliorate healthcare disparities and the global burden of cancer worldwide. In this review, we outline the current utility of FI for screening and detection in a range of cancer types.

Exploring the Use of C-Reactive Protein to Estimate the Pharmacodynamics of Vancomycin

BACKGROUND

C-reactive protein (CRP) pharmacodynamic (PD) models have the potential to provide adjunctive methods for predicting the individual exposure response to antimicrobial therapy. We investigated CRP PD linked to a vancomycin pharmacokinetic (PK) model using routinely collected data from noncritical care adults in secondary care.

METHODS

Patients receiving intermittent intravenous vancomycin therapy in secondary care were identified. A 2-compartment vancomycin PK model was linked to a previously described PD model describing CRP response. PK and PD parameters were estimated using a Non-Parametric Adaptive Grid technique. Exposure-response relationships were explored with vancomycin area-under-the-concentration-time-curve (AUC) and EC50 (concentration of drug that causes a half maximal effect) using the index, AUC:EC50, fitted to CRP data using a sigmoidal Emax model.

RESULTS

Twenty-nine individuals were included. Median age was 62 (21-97) years. Fifteen (52%) patients were microbiology confirmed. PK and PD models were adequately fitted (r 0.83 and 0.82, respectively). There was a wide variation observed in individual Bayesian posterior EC50 estimates (6.95-48.55 mg/L), with mean (SD) AUC:EC50 of 31.46 (29.22). AUC:EC50 was fitted to terminal CRP with AUC:EC50 >19 associated with lower CRP value at 96-120 hours of therapy (100 mg/L versus 44 mg/L; P < 0.01).

CONCLUSIONS

The use of AUC:EC50 has the potential to provide in vivo organism and host response data as an adjunct for in vitro minimum inhibitory concentration data, which is currently used as the gold standard PD index for vancomycin therapy. This index can be estimated using routinely collected clinical data. Future work must investigate the role of AUC:EC50 in a prospective cohort and explore linkage with direct patient outcomes.

Charge rearrangement and screening in a quantum point contact

Compressibility measurements are performed on a quantum point contact (QPC). Screening due to mobile charges in the QPC is measured quantitatively, using a second point contact. These measurements are performed from pinch-off through the opening of the first few modes in the QPC. While the measured signal closely matches a Thomas-Fermi-Poisson prediction, deviations from the classical behavior are apparent near the openings of the different modes. Density functional calculations attribute the deviations to a combination of a diverging density of states at the opening of each one-dimensional mode and exchange interaction, which is strongest for the first mode.

Tunable anomalous Hall effect in a nonferromagnetic system

We measure the low-field Hall resistivity of a magnetically doped two-dimensional electron gas as a function of temperature and electrically gated carrier density. Comparing these results with the carrier density extracted from Shubnikov-de Haas oscillations reveals an excess Hall resistivity that increases with decreasing temperature. This excess Hall resistivity qualitatively tracks the paramagnetic polarization of the sample, in analogy to the ferromagnetic anomalous Hall effect. The data are consistent with skew scattering of carriers by disorder near the crossover to localization.

In vitro activities of linezolid, meropenem, and quinupristin-dalfopristin against group C and G streptococci, including vancomycin-tolerant isolates

The in vitro activities of meropenem, linezolid, quinupristin-dalfopristin, vancomycin, and penicillin against 130 clinical isolates of group C and G streptococci, including vancomycin-tolerant isolates, were evaluated. Meropenem, linezolid, quinupristin-dalfopristin, vancomycin, and penicillin MICs at which 90% of the isolates were inhibited were 0.06, 2.0, 0.25, 0.5, and < or = 0.016 microg/ml, respectively. Meropenem, linezolid, quinupristin-dalfopristin, and penicillin were active against group C and G streptococci, including vancomycin-resistant strains.

1998 William J. Stickel Bronze Award. Antifungal activity of Melaleuca alternifolia (tea-tree) oil against various pathogenic organisms

Tea-tree oil (oil of Melaleuca alternifolia) has recently received much attention as a natural remedy for bacterial and fungal infections of the skin and mucosa. As with most naturally occurring agents, claims of effectiveness have been only anecdotal; however, several published studies have recently demonstrated tea-tree oil's antibacterial activity. This study was conducted to determine the activity of tea-tree oil against 58 clinical isolates: Candida albicans (n = 10), Trichophyton rubrum (n = 8), Trichophyton mentagrophytes (n = 9), Trichophyton tonsurans (n = 10), Aspergillus niger (n = 9), Penicillium species (n = 9), Epidermophyton floccosum (n = 2), and Microsporum gypsum (n = 1). Tea-tree oil showed inhibitory activity against all isolates tested except one strain of E floccosum. These in vitro results suggest that tea-tree oil may be useful in the treatment of yeast and fungal mucosal and skin infections.

Minimal inhibitory concentrations and minimal bactericidal concentrations of quinupristin/dalfopristin against clinical isolates of Corynebacterium jeikeium and Listeria monocytogenes

Thirty clinical isolates of Listeria monocytogenes and 30 clinical isolates of Corynebacterium jeikeium were tested against quinupristin/dalfopristin by the NCCLS broth macrodilution technique for determination of MICs. MBC testing was also performed on the 60 isolates. Quinupristin/dalfopristin MIC90 values against L. monocytogenes and C. jeikeium were 1.6 mg/L and 0.2 mg/L, respectively. Quinupristin/dalfopristin was bacteriostatic against these organisms.

Evaluation of interpretive criteria of agar dilution and disk diffusion susceptibility tests for Neisseria gonorrhoeae

Using strains of Neisseria gonorrhoeae from Western New York, the National Committee for Clinical Laboratory Standards' (NCCLS) interpretive criteria for disk diffusion susceptibility testing was evaluated on chocolate-Mueller-Hinton agar (CMH) and GC agar. The reference method for comparison was the NCCLS agar dilution minimum inhibitory concentration (MIC) method. Even though the zone sizes were significantly smaller on the CMH agar, the interpretations were not significantly different on either GC or CMH agars except for tetracycline. On the CMH agar, the number of tetracycline-resistant strains was greater than on GC agar: 3% of the strains failed to grow on CMH agar and 4% did not produce interpretable zone sizes for ceftriaxone. Therefore, the use of CMH is not recommended. There was a significant difference between the interpretative criteria of the MIC and the disk diffusion method only for tetracycline. Therefore, the NCCLS zone-diameter interpretation criteria for tetracycline does not seem applicable for N. gonorrhoeae isolates in the Buffalo, New York, area.

Antifungal susceptibility testing of yeasts: a brief overview

Antifungal susceptibility testing of yeasts has lacked reproducibility because of the absence of universally accepted guidelines. The major sources of variation in susceptibility testing have been attributed to the choice of medium and pH, inoculum preparation and size, incubation temperature and time, and end-point criteria. These parameters have been addressed by the National Committee for Clinical Laboratory Standards (NCCLS) Subcommittee on Antifungal Susceptibility Testing, and proposed guidelines have recently been published. Although major advances in antifungal susceptibility testing have been achieved, particularly through the efforts of the NCCLS subcommittee, the results of studies to date do not support a correlation between the results of in vitro susceptibility testing and in vivo response. Routine antifungal susceptibility testing of yeasts should therefore be discouraged until the methodology is standardized such that it predicts clinical outcome.

Splenic abscess as a complication of percutaneous nephrostomy

We report a case of splenic abscess as a complication of percutaneous nephrostomy tube placement. The patient was a sixty-three-year-old man suffering from a recurrence of transitional cell carcinoma of the bladder after cystectomy and neobladder substitution. Computed tomography of the abdomen identified the abscess, which was drained percutaneously. The patient's condition improved dramatically, and computed tomography showed complete resolution of the abscess two weeks after drainage. Splenic abscess is fatal if untreated and should be considered in a patient in whom sepsis or left lower pulmonary effusion develops after percutaneous manipulation of the kidney.