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Resistance and the war on pathogens: How does Stenotrophomonas maltophilia challenge modern medicine?
In the medical community, the war against pathogens has never stopped. However, with the rise of drug-resistant bacteria, many previously unimaginable germs have resurfaced. Among them, Stenotrophomonas maltophilia, as an atypical pathogen, is gradually attracting attention. This Gram-negative, aerobic, non-fermenting bacterium is difficult to eradicate in healthcare settings and is particularly common in immunocompromised patients. Its drug resistance poses many challenges to health care workers.
The naming history of this bacterium is very tortuous. It was first discovered as Bacterium bookeri and was classified into Pseudomonas and Xanthomonas. It was not until 1993 that with the development of bacterial taxonomy, it was established as the type species Stenotrophomonas.
Pathogenic mechanism
In clinical settings, S. maltophilia often adheres to moist surfaces, such as mechanical ventilation ducts and indwelling urinary catheters. This bacterium is highly advantageous in its ability to form and adhere to biofilms, and the risk of infection increases with the use of medical devices.
The outer membrane vesicles (OMVs) of S. maltophilia induce the inflammatory response in humans. These OMVs are cytotoxic to human lung epithelial cells and promote the gene expression of pro-inflammatory cytokines and chemokines, such as IL- 1β, IL-6, IL-8 and TNF-α.
It is worth mentioning that this bacterium is not highly pathogenic, but under certain circumstances, such as when coexisting with other pathogens, it will display its unique pathogenic mechanism. In patients with suppressed immune systems, such as those with cystic fibrosis, infection rates are increasing year by year, implying the increasing importance of S. maltophilia as a clinical pathogen.
Therapeutic Challenges
Treating S. maltophilia infections is challenging, primarily because of its natural resistance to multiple broad-spectrum antibiotics, especially all carbapenems. This makes the bacterium special not only in its pathogenicity but also in the treatment difficulties it poses.
In clinical practice, antibiotics are only used when infected prostheses cannot be removed, and many infections can be improved by removing these prostheses.Appropriate antibiotic selection depends on bacterial susceptibility, and many strains of S. maltophilia respond to combination therapy (eg, trimethoprim-sulfamethoxazole) and certain beta-lactams. However, as resistance increases, treatment options become increasingly limited.
Epidemiology
S. maltophilia infection is associated with high mortality in patients who are severely immunosuppressed, especially those with HIV infection, cancer, and those receiving broad-spectrum antibiotics. Patients in these groups are more susceptible to this pathogen, calling for our close attention to its epidemiological dynamics.
Although the epidemiology of S. maltophilia still requires further study, observable risk factors such as mechanical ventilation, central venous catheter placement, recent surgery, and disorders make this bacterium not to be underestimated.
Conclusion
As the problem of drug resistance intensifies, the existence of Stenotrophomonas maltophilia not only challenges the traditional infection control mechanism, but also changes the model of clinical treatment. Faced with this ever-evolving pathogen, healthcare workers need to continually update their knowledge and be vigilant about potential infections and their resistance to antibiotics. In this war against antibiotic resistance and pathogens, are we adequately prepared to face new challenges?
