Development of resistance may necessitate alternative therapies for S. maltophilia
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Patients previously treated with trimethoprim-sulfamethoxazole for Stenotrophomonas maltophilia may require alternative therapies because of high rates of resistance to the agent, according to a review examining the epidemiology of the infection.
“S. maltophilia is a gram-negative, multidrug-resistant organism that is typically hospital acquired and associated with high morbidity and mortality,” Ahmed M. Hamdi, MD, of the division of infectious diseases at the Mayo Clinic, and colleagues wrote. “Worldwide, the rate of S. maltophilia infections has increased in past decades, likely attributable to the increase in the population at risk [including those who are critically ill; patients with chronic obstructive pulmonary disease, HIV or an organ transplant; patients on prolonged therapy with broad-spectrum antibiotics; or patients with an extended need for assisted ventilation, respiratory tract S. maltophilia colonization, and prolonged neutropenia] as a result of advances in care of immunocompromised patients, also driven by use of invasive devices and broad-spectrum antibiotics.”
Hamdi and colleagues aimed to better define the epidemiology of S. maltophilia, including morbidity, complications, recurrence and mortality outcomes, through a retrospective review of 10-year data from hospitalized adults at the Mayo Clinic.
In total, 98 patients were studied. Most of these patients (74.5%) were immunocompromised; active malignancies were noted for 62.2% of patients. Fewer patients had a history of organ transplant (31.6%) or neutropenia (36.7%). The majority of patients (83.6%) also had high Charlson Comorbidity Index scores (≥ 3).
Hamdi and colleagues found that the most common source of infection was catheter related (63.3%). Most of the isolates identified (65%) were resistant to ceftazidime; 2.1% were resistant to trimethoprim-sulfamethoxazole (TMP-SMX) and 23.4% to levofloxacin. Researchers also determined that all-cause in-hospital mortality was 29.6%, with the highest mortality (53.8%) observed in patients with pulmonary sources of bacteremia. According to the study, TMP-SMX had “reliable activity” among the analyzed patients, although resistance was found in patients with recent TMP-SMX exposure. Of the 98 patients in the study, five were exposed to TMP-SMX in the 30 days before presentation; resistance to TMP-SMX was demonstrated in one of these individuals.
The prognosis for patients with S. maltophilia infection was generally poor, Hamdi and colleagues found. All-cause in-hospital 30-day mortality was 29.6%. Mortality ranged from 21% in patients with line-associated S. maltophilia infections to 57.1% in patients with S. maltophilia bacteremia from a pulmonary source.
“Infections with S. maltophilia should be considered in critically ill patients with prolonged hospitalization who are receiving broad-spectrum antibiotics,” the authors concluded. “Although TMP-SMX remains the treatment of choice, alternative therapy might be needed in those with previous exposure to TMP-SMX due to higher rates of resistance.” – by Caitlyn Stulpin
Disclosures: The authors report no relevant financial disclosures.
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