Attention-based Knowledge Graph Representation Learning for Predicting Drug-drug Interactions

Drug-drug interactions (DDIs) are known as the main cause of life-threatening adverse events, and their identification is a key task in drug development. Existing computational algorithms mainly solve this problem by using advanced representation learning techniques. Though effective, few of them are capable of performing their tasks on biomedical knowledge graphs (KGs) that provide more detailed information about drug attributes and drug-related triple facts. In this work, an attention-based KG representation learning framework, namely DDKG, is proposed to fully utilize the information of KGs for improved performance of DDI prediction. In particular, DDKG first initializes the representations of drugs with their embeddings derived from drug attributes with an encoder-decoder layer, and then learns the representations of drugs by recursively propagating and aggregating first-order neighboring information along top-ranked network paths determined by neighboring node embeddings and triple facts. Last, DDKG estimates the probability of being interacting for pairwise drugs with their representations in an end-to-end manner. To evaluate the effectiveness of DDKG, extensive experiments have been conducted on two practical datasets with different sizes, and the results demonstrate that DDKG is superior to state-of-the-art algorithms on the DDI prediction task in terms of different evaluation metrics across all datasets.

Assessment of the in vitro activity of azithromycin niosomes alone and in combination with levofloxacin on extensively drug-resistant Klebsiella pneumoniae clinical isolates

BACKGROUND AND AIM

Extensively drug-resistant (XDR) Klebsiella pneumoniae represent a major threat in intensive care units. The aim of the current study was to formulate a niosomal form of azithromycin (AZM) and to evaluate its in vitro effect on XDR K. pneumoniae as a single agent or in combination with levofloxacin.

MATERIAL AND METHODS

Forty XDR K. pneumoniae isolates (23 colistin-sensitive and 17 colistin-resistant) were included in the study. Formulation and characterization of AZM niosomes were performed. The in vitro effect of AZM solution/niosomes alone and in combination (with levofloxacin) was investigated using the checkerboard assay, confirmed with time-kill assay and post-antibiotic effect (PAE).

RESULTS

The AZM niosome mean minimal inhibitory concentration (MIC) (187.4 ± 209.1 μg/mL) was significantly lower than that of the AZM solution (342.5 ± 343.4 μg/mL). AZM niosomes/levofloxacin revealed a 40% synergistic effect compared to 20% with AZM solution/levofloxacin. No antagonistic effect was detected. The mean MIC values of both AZM niosomes and AZM solution were lower in the colistin-resistant group than in the colistin-sensitive group. The mean PAE time of AZM niosomes (2.3 ± 1.09 h) was statistically significantly longer than that of the AZM solution (1.37 ± 0.5 h) (p = 0.023).

CONCLUSION

AZM niosomes were proved to be more effective than AZM solution against XDR K. pneumoniae, even colistin-resistant isolates.

Levofloxacin for NIH Category II Chronic Bacterial Prostatitis: A Real-Life Study

BACKGROUND

Mounting worldwide resistance trends make the use of fluoroquinolone (FQ) antibacterial agents increasingly difficult. This is felt more acutely in the case of urogenital infections, which are mainly caused by Gram-negative pathogens. For years, levofloxacin and other FQs have been the first-line drugs for treating National Institutes of Health (NIH) category II chronic bacteria prostatitis (CBP). Eradication rates achieved by levofloxacin in the frame of randomized trials vary greatly, ranging between 71 and 86%.

OBJECTIVES

This was a retrospective observational study to investigate the efficacy of levofloxacin against CBP in a real-life setting (urological outpatient wards).

METHODS

A database including the clinical records of >2,500 CBP patients was reviewed. Patients were selected based on strict inclusion criteria. They were treated for 4 weeks with 500 mg levofloxacin per day, alone or combined with other antibacterials. Besides standard urological procedures including the 4-glass test for pathogen isolation, international symptom questionnaires (the NIH Chronic Prostatitis Symptom Index [NIH-CPSI] and International Prostate Symptom Score [IPSS]) were administered.

RESULTS

Pathogen eradication was achieved in 79% of the cases treated with levofloxacin as a single agent and 87.8% of patients who received a combination of levofloxacin and azithromycin. The 11% increase in the eradication rate in the latter group is statistically significant. In addition, the levofloxacin-azithromycin combination caused a significant decrease in prostate volume and significantly increased the bladder-voided volume. IPSS and NIH-CPSI values and the urinary peak flow rate decreased to a similar extent in both treatment groups. No adverse effects were reported by patients belonging to either treatment group.

CONCLUSION

Levofloxacin retained its therapeutic efficacy in patients assessed in a real-life setting, and high eradication rates were attained when it was administered as a single agent. A combination of an FQ with azithromycin induced a significant improvement of eradication rates. This strategy may be an interesting option in both first-referral and relapsing cases, although caution should be exercised when patients are at risk of developing arrhythmias, tendinitis, or other adverse effects.

Azithromycin: mechanisms of action and their relevance for clinical applications

Azithromycin is a macrolide antibiotic which inhibits bacterial protein synthesis, quorum-sensing and reduces the formation of biofilm. Accumulating effectively in cells, particularly phagocytes, it is delivered in high concentrations to sites of infection, as reflected in rapid plasma clearance and extensive tissue distribution. Azithromycin is indicated for respiratory, urogenital, dermal and other bacterial infections, and exerts immunomodulatory effects in chronic inflammatory disorders, including diffuse panbronchiolitis, post-transplant bronchiolitis and rosacea. Modulation of host responses facilitates its long-term therapeutic benefit in cystic fibrosis, non-cystic fibrosis bronchiectasis, exacerbations of chronic obstructive pulmonary disease (COPD) and non-eosinophilic asthma. Initial, stimulatory effects of azithromycin on immune and epithelial cells, involving interactions with phospholipids and Erk1/2, are followed by later modulation of transcription factors AP-1, NFκB, inflammatory cytokine and mucin release. Delayed inhibitory effects on cell function and high lysosomal accumulation accompany disruption of protein and intracellular lipid transport, regulation of surface receptor expression, of macrophage phenotype and autophagy. These later changes underlie many immunomodulatory effects of azithromycin, contributing to resolution of acute infections and reduction of exacerbations in chronic airway diseases. A sub-group of post-transplant bronchiolitis patients appears to be sensitive to azithromycin, as may be patients with severe sepsis. Other promising indications include chronic prostatitis and periodontitis, but weak activity in malaria is unlikely to prove crucial. Long-term administration of azithromycin must be balanced against the potential for increased bacterial resistance. Azithromycin has a very good record of safety, but recent reports indicate rare cases of cardiac torsades des pointes in patients at risk.