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Published on: January 3, 2020
Cytotoxic activity of clinical Stenotrophomonas maltophilia
P M S Figueirêdo1, M T Furumura, A M Santos
1Departamento de Microbiologia e Imunologia, Instituto de Biologia, Universidade Estadual de Campinas, SP, Brazil.
Aims:
To determine the potential virulence factors produced by culture supernatants of clinical isolates of Stenotrophomonas maltophilia.
Methods And Results:
Culture supernatants of clinical isolates of S. maltophilia were assayed for haemolytic, enzymatic (lipase, protease and phospholipase) and cytotoxic activity. Cytotoxic activity was assayed in Vero (African green monkey), HeLa (human cervix) and HEp-2 (human larynx epidermoid carcinoma) cells. Microscopic analyses revealed intensive rounding, loss of intercellular junctions and membrane alterations (blebbing) followed by death of HEp-2 cells. In Vero and HeLa cells, the cytotoxic effects were characterized by vigorous endocytosis and cell aggregation. The viability of cultured mammalian cells was determined with neutral red and demonstrated that the sensitivity among the cells was different. This activity was inactivated by heating at 56 degrees C for 15 min and protease inhibitors did not inhibit cytotoxic activity. The clinical S. maltophilia presented a cell-free haemolytic activity similar to the 'hot-cold' haemolysins.
Conclusions:
S. maltophilia culture supernatants caused vigorous endocytosis and cell aggregation in HeLa and Vero cells, produced haemolytic and enzymatic activities.
Significance And Impact Of The Study:
This work revealed the presence of putative virulence factors that could be associated with human infections involving Stenotrophomonas maltophilia strains.
Insights
Stenotrophomonas maltophilia virulence factors were identified in culture supernatants. These factors, including haemolytic and enzymatic activities, contribute to S. maltophilia
Area of Science:
- Microbiology
- Infectious Diseases
- Bacterial Pathogenesis
Background:
- Stenotrophomonas maltophilia is an opportunistic pathogen causing severe human infections.
- Understanding its virulence factors is crucial for developing effective treatments.
Purpose of the Study:
- To investigate the potential virulence factors produced by clinical isolates of Stenotrophomonas maltophilia.
- To characterize the haemolytic, enzymatic, and cytotoxic activities of S. maltophilia culture supernatants.
Main Methods:
- Culture supernatants of S. maltophilia were tested for haemolytic, lipase, protease, and phospholipase activity.
- Cytotoxicity was assessed using Vero, HeLa, and HEp-2 cell lines.
- Cell viability was measured using the neutral red assay.
Main Results:
- S. maltophilia supernatants exhibited haemolytic activity and enzymatic activities (lipase, protease, phospholipase).
- Cytotoxic effects observed included cell rounding, loss of intercellular junctions, membrane blebbing, and cell death in HEp-2 cells.
- Vigorous endocytosis and cell aggregation were noted in Vero and HeLa cells, with varying sensitivity among cell lines.
Conclusions:
- Stenotrophomonas maltophilia culture supernatants possess virulence factors contributing to cytotoxicity, haemolysis, and enzymatic activity.
- These identified factors may play a significant role in S. maltophilia-associated human infections.
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