From the Research
When treating Stenotrophomonas maltophilia hospital-acquired pneumonia (HAP), the first-line treatment is trimethoprim-sulfamethoxazole (TMP-SMX) at a dosage of 5 mg/kg of the trimethoprim component every 8-12 hours for 7-14 days, depending on clinical response, as recommended by the most recent study 1. The recommended minimum duration is 7 days, but treatment should be extended if the patient shows delayed clinical improvement. Special considerations include:
- Monitoring for TMP-SMX side effects such as rash, bone marrow suppression, and hyperkalemia, especially in patients with renal impairment where dose adjustment may be necessary.
- For patients with TMP-SMX allergies or resistance, alternative options include fluoroquinolones (levofloxacin 750 mg daily), minocycline (100 mg twice daily), or ceftazidime (2g every 8 hours), though these have lower success rates.
- Combination therapy may be considered for severe infections or immunocompromised patients. S. maltophilia is intrinsically resistant to many antibiotics including carbapenems, most beta-lactams, and aminoglycosides, making antibiotic selection challenging. Treatment should be guided by susceptibility testing whenever possible, as resistance patterns can vary. Additionally, addressing any removable sources of infection such as central lines or urinary catheters is crucial for successful treatment. According to the latest guidance issued by the Infectious Diseases Society of America (IDSA) 2, novel therapeutic options such as cefiderocol (FDC) and ceftazidime-avibactam plus aztreonam (CZA-ATM) are suggested, based on limited but promising clinical data. However, the most recent study 1 recommends a TMP-SMX-based regimen for the treatment of S. maltophilia infections, as it is associated with reduced treatment failure. It is also important to note that the predictive factors for an unfavorable outcome were severity of illness, septic shock, and non-use of TMP-SMX 1. Other studies have shown that levofloxacin is a reasonable alternative to TMP-SMX for the treatment of bloodstream and lower respiratory tract infections caused by S. maltophilia 3, and minocycline and doxycycline may be options to treat S. maltophilia pneumonia, but conclusive clinical data continue to be lacking 4. However, these studies are not as recent or of the same quality as the study by 1, which provides the most up-to-date guidance on the treatment of S. maltophilia infections.