For S. maltophilia Infections, Consider Minocycline Monotherapy

S. maltophilia infections are known as being inherently resistant with limited treatment options
S. maltophilia infections are known as being inherently resistant with limited treatment options

NEW ORLEANS, LA—Minocycline “may be a good choice” for infections caused by Stenotrophomonas maltophilia, an inherently-resistant organism with limited treatment options, concluded authors of a retrospective study presented at IDWeek 2016.

"Our data suggest that minocycline or fluoroquinolones should be considered over initial treatment trimethoprim-sulfamethoxazole in treatment of S. maltophilia infections," said lead study author Shauna Jacobson, PharmD, an infectious disease pharmacist at Orlando Health in Orlando, FL.

Trimethoprim-sulfamethoxazole (TMP/SMX) is a first-line therapy for S. maltophilia. While fluoroquinolones appear to have similar clinical success, however,  the evidence base is limited.

“Due to high susceptibility rates (99%) and clinical success of minocycline treatment at our institution, we compared the clinical outcomes of these agents for S. maltophilia infections,” Dr. Jacobson and her colleagues reported in a poster presentation.

The study team retrospectively reviewed patient records of adults with a documented S. maltophilia culture who received minocycline, TMP/SMX, or a fluoroquinolone as monotherapy during 2010–2016. Exclusion criteria included initial monotherapy not being administered for ≥ 48 hours, pregnancy, cystic fibrosis diagnosis, or previous treatment of S. maltophilia in the previous year.

Among the 108 patients included in the study, monotherapy with minocycline, TMP/SMX, or a fluoroquinolone was administered to 31%, 43%, and 26% of patients, respectively. 

Clinical failure was lower in the minocycline versus TMP/SMX groups (30% vs. 66%; P=0.001) and in the fluoroquinolone vs. TMP/SMX groups (28.6 vs. 66%; P =0.001). Therapy discontinuation rates were significantly higher for the TMP/SMX group (47%) than fluoroquinolones (7%) or minocycline (6%; P<0.001).

However, Dr. Jacobson cautioned that patients in the TMP/SMX group were more frequently on ventilation (66% vs. 28.6% in the fluoroquinolone group and 48.5% in the minocycline group; P<0.001). TMP/SMX group patients also had higher APACHE-II scores (21 vs. 13 in the fluoroquinolone group and 16 in the minocycline group; P=0.045), she noted.

When the researchers conducted multivariate analysis of those patients whose APACHE-II scores exceeded 20 (n=53), however, clinical failure rates remained lower among patients treated with minocycline or a fluoroquinolone, compared to TMP/SMX. 

Despite higher rates of baseline illness, patients treated with minocycline had a lower incidence of clinical failure than those treated with TMP/SMX, and similar incidence as those treated with a fluoroquinolone, Dr. Jacobson concluded.