Phenotypic Features of Pediatric Bronchiectasis Exacerbations Associated With Symptom Resolution After 14 Days of Oral Antibiotic Treatment.

BACKGROUND: Respiratory exacerbations in children and adolescents with bronchiectasis are treated with antibiotics. However, antibiotics can have variable interindividual effects when treating exacerbations. RESEARCH QUESTION: Can phenotypic features associated with symptom resolution after a 14-day course of oral antibiotics for a nonsevere exacerbation of bronchiectasis be identified? STUDY DESIGN AND METHODS: Combining data from two multicenter randomized controlled trials, we identified 217 children with bronchiectasis assigned to at least 14 days of oral antibiotics to treat nonsevere (nonhospitalized) exacerbations. Univariable and then multivariable logistic regression were used to identify factors associated with symptom resolution within 14 days of commencing antibiotics. Identified associations were re-evaluated by mediation analysis. RESULTS: Of the 217 study participants (52% male patients), 41% were Indigenous (Australian First Nations, New Zealand Maori, or Pacific Islander). The median age was 6.6 years (interquartile range, 4.0-10.1 years). By day 14, symptoms had resolved in 130 children (responders), but persisted in the remaining 87 children (nonresponders). Multivariable analysis found those who were Indigenous (adjusted OR [AOR], 3.59; 95% CI, 1.35-9.54) or showed new abnormal auscultatory findings (AOR, 3.85; 95% CI, 1.56-9.52) were more likely to be responders, whereas those with multiple bronchiectatic lobes at diagnosis (AOR, 0.66; 95% CI, 0.46-0.95) or higher cough scores when starting exacerbation treatment (AOR, 0.55; 95% CI, 0.34-0.90) were more likely to be nonresponders. Detecting a respiratory virus at the beginning of an exacerbation was not associated with antibiotic failure at 14 days. INTERPRETATION: Children with Indigenous ethnicity, milder bronchiectasis, mild exacerbations (low reported cough scores), or new abnormal auscultatory signs are more likely to respond to appropriate oral antibiotics than those without these features. These patient and exacerbation phenotypes may assist clinical management and development of biomarkers to identify those whose symptoms are more likely to resolve after 14 days of oral antibiotics. TRIAL REGISTRY: Australian New Zealand Clinical Trials Registry; Nos.: ACTRN12612000011886 and ACTRN12612000010897; URL: https://www.anzctr.org.au.

The Transcriptomic Signature of Tigecycline in Acinetobacter baumannii.

Tigecycline, a protein translation inhibitor, is a treatment of last resort for infections caused by the opportunistic multidrug resistance human pathogen Acinetobacter baumannii. However, strains resistant to tigecycline were reported not long after its clinical introduction. Translation inhibitor antibiotics perturb ribosome function and induce the reduction of (p)ppGpp, an alarmone involved in the stringent response that negatively modulates ribosome production. Through RNA sequencing, this study revealed a significant reduction in the transcription of genes in citric acid cycle and cell respiration, suggesting tigecycline inhibits or slows down bacterial growth. Our results indicated that the drug-induced reduction of (p)ppGpp level promoted the production but diminished the degradation of ribosomes, which mitigates the translational inhibition effect by tigecycline. The reduction of (p)ppGpp also led to a decrease of transcription coupled nucleotide excision repair which likely increases the chances of development of tigecycline resistant mutants. Increased expression of genes linked to horizontal gene transfer were also observed. The most upregulated gene, rtcB, involving in RNA repair, is either a direct tigecycline stress response or is in response to the transcription de-repression of a toxin-antitoxin system. The most down-regulated genes encode two ß-lactamases, which is a possible by-product of tigecycline-induced reduction in transcription of genes associated with peptidoglycan biogenesis. This transcriptomics study provides a global genetic view of why A. baumannii is able to rapidly develop tigecycline resistance.

Rapid and Sensitive Detection of Bacteria Response to Antibiotics Using Nanoporous Membrane and Graphene Quantum Dot (GQDs)-Based Electrochemical Biosensors.

The wide abuse of antibiotics has accelerated bacterial multiresistance, which means there is a need to develop tools for rapid detection and characterization of bacterial response to antibiotics in the management of infections. In the study, an electrochemical biosensor based on nanoporous alumina membrane and graphene quantum dots (GQDs) was developed for bacterial response to antibiotics detection. Anti-Salmonella antibody was conjugated with amino-modified GQDs by glutaraldehyde and immobilized on silanized nanoporous alumina membranes for Salmonella bacteria capture. The impedance signals across nanoporous membranes could monitor the capture of bacteria on nanoporous membranes as well as bacterial response to antibiotics. This nanoporous membrane and GQD-based electrochemical biosensor achieved rapid detection of bacterial response to antibiotics within 30 min, and the detection limit could reach the pM level. It was capable of investigating the response of bacteria exposed to antibiotics much more rapidly and conveniently than traditional tools. The capability of studying the dynamic effects of antibiotics on bacteria has potential applications in the field of monitoring disease therapy, detecting comprehensive food safety hazards and even life in hostile environment.