P06 The use of procalcitonin testing to improve antibiotic stewardship in all cause respiratory admissions: a retrospective analysis

Background

Improving antibiotic stewardship whilst simultaneously optimizing patient safety is a perpetually vexing clinical conundrum, which has been compounded by the current COVID-19 pandemic. Procalcitonin (PCT) measurement has previously demonstrated utility in this regard, when combined with routine clinical investigation, in certain patient populations.

Objectives

To assess whether the inclusion of PCT measurement as part of routine clinical care, instituted during a quality improvement project (QIP), increases the appropriateness of antibiotic administration.

Methods

A retrospective analysis was performed on 6 month interim data obtained from May to October 2021 during a QIP, which assessed the effect of PCT measurement on antimicrobial stewardship. All patients included had a primary diagnosis of respiratory illness and were analysed both together and as COVID-19 and non-COVID-19 subgroups to assess how often antibiotics were commenced on admission, duration of treatment and appropriateness of use. Finally, as sending microbiological samples made up part of the protocol, sample sending frequency was also studied.

Results

Thirty patients were included in both the COVID-19 and non-COVID-19 baseline subgroups who did not have PCT testing performed. Fifty-two patients were included in the PCT subgroup (27 COVID-19 positive and 25 COVID-19 negative). Following introduction of PCT testing, commencement of antibiotics on admission was reduced overall and in the COVID-19 positive subgroup (P = 0.0426 and P = 0.0446, respectively) with a significant decrease in inappropriate antibiotic prescribing in these two groups (P = 0.011 and P = 0.0157, respectively) and a trend towards reduced prescribing of AWaRe watch group antibiotics such as ceftriaxone. However, once prescribed, there was no difference in duration of antibiotic treatment or the frequency of microbiological sampling.

Conclusions

The data from this interim data analysis demonstrate that PCT measurement, when combined with routine clinical investigations in the acute respiratory setting, can be used to reduce inappropriate antibiotic prescribing. This was significantly reduced overall and in the COVID-19 positive subgroup but lost statistical significance in the COVID-19 negative subgroup, where it could be hypothesized that heterogeneity and inclusion of respiratory diseases where PCT has previously encountered difficulty in determining the presence of acute bacterial infection may be the cause. The significant effect demonstrated in the COVID-19 positive subgroup suggests particular utility in this patient population.

Anatomical characterization of Cre driver mice for neural circuit mapping and manipulation

Significant advances in circuit-level analyses of the brain require tools that allow for labeling, modulation of gene expression, and monitoring and manipulation of cellular activity in specific cell types and/or anatomical regions. Large-scale projects and individual laboratories have produced hundreds of gene-specific promoter-driven Cre mouse lines invaluable for enabling genetic access to subpopulations of cells in the brain. However, the potential utility of each line may not be fully realized without systematic whole brain characterization of transgene expression patterns. We established a high-throughput in situ hybridization (ISH), imaging and data processing pipeline to describe whole brain gene expression patterns in Cre driver mice. Currently, anatomical data from over 100 Cre driver lines are publicly available via the Allen Institute's Transgenic Characterization database, which can be used to assist researchers in choosing the appropriate Cre drivers for functional, molecular, or connectional studies of different regions and/or cell types in the brain.

A high-resolution spatiotemporal atlas of gene expression of the developing mouse brain

To provide a temporal framework for the genoarchitecture of brain development, we generated in situ hybridization data for embryonic and postnatal mouse brain at seven developmental stages for ∼2,100 genes, which were processed with an automated informatics pipeline and manually annotated. This resource comprises 434,946 images, seven reference atlases, an ontogenetic ontology, and tools to explore coexpression of genes across neurodevelopment. Gene sets coinciding with developmental phenomena were identified. A temporal shift in the principles governing the molecular organization of the brain was detected, with transient neuromeric, plate-based organization of the brain present at E11.5 and E13.5. Finally, these data provided a transcription factor code that discriminates brain structures and identifies the developmental age of a tissue, providing a foundation for eventual genetic manipulation or tracking of specific brain structures over development. The resource is available as the Allen Developing Mouse Brain Atlas (http://developingmouse.brain-map.org).

Synthesis and antibacterial activity of novel C12 ethyl ketolides

A novel series of C(12) ethyl erythromycin derivatives have been discovered which exhibit in vitro and in vivo potency against key respiratory pathogens, including those resistant to erythromycin. The C(12) modification involves replacing the natural C(12) methyl group in the erythromycin core with an ethyl group via chemical synthesis. From the C(12) ethyl macrolide core, a series of C(12) ethyl ketolides were prepared and tested for antibacterial activity against a panel of relevant clinical isolates. Several compounds were found to be potent against macrolide-sensitive and -resistant bacteria, whether resistance was due to ribosome methylation (erm) or efflux (mef). In particular, the C(12) ethyl ketolides 4k,4s,4q,4m, and 4t showed a similar antimicrobial spectrum and comparable activity to the commercial ketolide telithromycin. The in vivo efficacy of several C(12) ethyl ketolides was demonstrated in a mouse infection model with Streptococcus pneumoniae as pathogen.

Synthesis and Antibacterial Activity of Novel C12 Vinyl Ketolides

A novel series of C12 vinyl erythromycin derivatives have been discovered which exhibit in vitro and in vivo potency against key respiratory pathogens. The C12 modification involves replacing the natural C12 methyl group in the erythromycin core with a vinyl group via chemical synthesis. From the C12 vinyl macrolide core, a series of C12 vinyl ketolides was prepared. Several compounds were found to be potent against macrolide-sensitive and -resistant bacteria. The C12 vinyl ketolides 6j and 6k showed a similar antimicrobial spectrum and comparable activity to the commercial ketolide telithromycin. However, the pharmacokinetic profiles of C12 vinyl ketolides 6j and 6k in rats differ from that of telithromycin by having higher lung-to-plasma ratios, larger volumes of distribution, and longer half-lives. These pharmacokinetic differences have a pharmacodynamic effect as both 6j and 6k exhibited better in vivo efficacy than telithromycin in rat lung infection models against Streptococcus pneumoniae and Haemophilus influenzae.

Immunomodulation by theophylline in asthma. Demonstration by withdrawal of therapy

Theophylline is the most widely used anti-asthma drug worldwide and is classified as a bronchodilator, although there is increasing evidence that it may have immunomodulatory effects. We have investigated the effects of theophylline withdrawal under placebo control in 27 asthmatic patients (25 to 70 yr) treated with long-term theophylline who were also treated with high dose inhaled corticosteroids. We measured asthma symptoms (diary card), lung function (spirometry and home records of peak expiratory flow), and peripheral leukocyte populations using dual color flow cytometry. In eight of these patients, we examined fiberoptic bronchial biopsies by immunocytochemistry. We also studied peripheral blood lymphocytes in eight asthmatic patients who have never received theophylline. Mean steady state plasma theophylline concentrations during theophylline therapy were 8.6 +/- 0.9 mg/L. Theophylline withdrawal was associated with a significant increase in asthma symptoms, particularly at night, and a fall in spirometry and morning peak flow. This was accompanied by a significant fall in peripheral blood monocytes (CD14+, activated CD4+ T-lymphocytes (CD4+/CD25+) and activated CD8+ T-cells (CD8+/HLA-DR+) in patients with a plasma theophylline > 5 mg/L. The lymphocyte populations in theophylline-naive patients were similar to those found after theophylline withdrawal. Bronchial biopsies showed a mirror image of the peripheral blood with an increase in CD4+ and CD8+ lymphocytes in the airway. Chronic treatment with theophylline, even at low plasma concentrations, controls asthma symptoms and has effects on T-lymphocyte populations in the peripheral blood which are the inverse of those observed in the airways.(ABSTRACT TRUNCATED AT 250 WORDS)

Occupational asthma

Occupational asthma is becoming an increasingly common problem worldwide. To date however, the impact of this disorder in Ireland has not been evaluated. In this present study we document 39 cases of occupational asthma presenting to St. Vincent's Hospital between 1978 and 1988 and evaluate the patient characteristics, the occupationals involved, the causative agents and clinical course and outcome. The characteristics of the occupational asthma group were striking when compared to traditional occupational lung diseases, such as the pneumoconioses. These features were (i) the relatively young age--30 patients (77%) developed their disease by the age of 35, (ii) the presence of a substantial group of women--31% of the study group, and (iii) the relatively rapid onset of asthma after taking up employment--56% had asthma within three years of exposure. In contrast the pneumoconioses affect older, preponderantly male workers who manifest clinically symptomatic disease after decades of exposure. Long standing traditional industries were well represented ranging from milling and the bakery trade to textiles and printing. However, there was an even larger contribution from the more modern, high technology sector particularily the chemical, electronic and plastic industries.