For S. maltophilia Infections, Consider Minocycline Monotherapy

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.

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.