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Updated: Sep 26, 2026
Automated, High-Throughput Detection of Bacterial Adherence to Host Cells
Published on: September 17, 2021
Effects of erythromycin on Pseudomonas aeruginosa adherence to collagen and morphology in vitro
1Dept of Medicine, The University of Hong Kong, Queen Mary Hospital, Pokfulam, Hong Kong SAR, China. kwttsang@hku.hk
Abstract:
The airways of patients with bronchiectasis and cystic fibrosis are often chronically colonised by Pseudomonas aeruginosa (PA), which is virtually impossible to eradicate. Low-dose erythromycin (EM), for unknown mechanisms, is efficacious in bronchiectasis and diffuse panbronchiolitis. In this study, an in vitro model to investigate PA adherence to human type IV basement collagen was developed by using scanning electron microscopy (SEM). There were significantly less PA bacilli per 20 random SEM fields (4,000x) when PA was cultured in 0.05, 0.5 and 5 microg x mL(-1) of EM compared with control (absence of EM). Adherence density (20 SEM fields x log(-1) inocular size) for PA obtained from no EM (56.8 +/- 43.16) was significantly higher than that obtained from 0.05, 0.5, and 5 microg x mL(-1) EM (21.5 +/- 17.56, 23.3 +/- 16.65, and 21.4 +/- 12.65 respectively). By using SEM it was found that PA, when incubated in EM (0.05, 0.5, 5 microg x mL(-1)) had a significant reduction in its diagonal length, radius, height, volume and surface area. It is possible, therefore, that these misshaped Pseudomonas aeruginosa bacilli are more susceptible to host defence mechanisms, while at the same time less adherent to the basement membrane of the airway in vivo. Therefore, this could help explain the clinical efficacy of low-dose erythromycin therapy on patients with Pseudomonas aeoruginosa infection.
Insights
Low-dose erythromycin (EM) alters Pseudomonas aeruginosa (PA) shape and reduces its adherence to airway surfaces. This mechanism may explain EM
Area of Science:
- Microbiology
- Pulmonary Medicine
- Pharmacology
Background:
- Chronic Pseudomonas aeruginosa (PA) colonization is a hallmark of bronchiectasis and cystic fibrosis, proving difficult to eradicate.
- Low-dose erythromycin (EM) demonstrates clinical efficacy in these conditions through poorly understood mechanisms.
Purpose of the Study:
- To investigate the in vitro effects of low-dose erythromycin on PA adherence to human type IV basement collagen.
- To elucidate potential mechanisms behind erythromycin's therapeutic benefits in PA-infected airway diseases.
Main Methods:
- Development of an in vitro model using scanning electron microscopy (SEM) to assess PA adherence to type IV basement collagen.
- Quantitative analysis of PA adherence density and morphological changes after incubation with varying concentrations of EM.
Main Results:
- EM significantly reduced PA adherence to type IV basement collagen compared to controls.
- PA cultured with EM exhibited significant reductions in size and volume, becoming misshapen.
- Adherence density decreased from 56.8 in controls to approximately 21-23 with EM treatment.
Conclusions:
- Low-dose erythromycin alters PA morphology, reducing its adherence to basement membranes.
- These morphological changes may enhance susceptibility to host defenses and explain clinical efficacy in PA infections.
