Evaluation of Trimethoprim/Sulfamethoxazole (SXT), Minocycline, Tigecycline, Moxifloxacin, and Ceftazidime Alone and in Combinations for SXT-Susceptible and SXT-Resistant Stenotrophomonas maltophilia by In Vitro Time-Kill Experiments

Abstract

BackgroundThe optimal therapy for infections caused by Stenotrophomonas maltophilia (S. maltophilia) has not yet been established. The objective of our study was to evaluate the efficacy of trimethoprim/sulfamethoxazole (SXT), minocycline, tigecycline, moxifloxacin, levofloxacin, ticarcillin-clavulanate, polymyxin E, chloramphenicol, and ceftazidime against clinical isolated S. maltophilia strains by susceptibility testing and carried out time-kill experiments in potential antimicrobials.MethodsThe agar dilution method was used to test susceptibility of nine candidate antimicrobials, and time-killing experiments were carried out to evaluate the efficacy of SXT, minocycline, tigecycline, moxifloxacin, levofloxacin, and ceftazidime both alone and in combinations at clinically relevant antimicrobial concentrations.ResultsThe susceptibility to SXT, minocycline, tigecycline, moxifloxacin, levofloxacin, ticarcillin-clavulanate, chloramphenicol, polymyxin E, and ceftazidime were 93.8%, 95.0%, 83.8%, 80.0%, 76.3%, 76.3%, 37.5%, 22.5%, and 20.0% against 80 clinical consecutively isolated strains, respectively. Minocycline and tigecycline showed consistent active against 22 SXT-resistant strains. However, resistance rates were high in the remaining antimicrobial agents against SXT-resistant strains. In time-kill experiments, there were no synergisms in most drug combinations in time-kill experiments. SXT plus moxifloxacin displayed synergism when strains with low moxifloxacin MICs. Moxifloxacin plus Minocycline and moxifloxacin plus tigecycline displayed synergism in few strains. No antagonisms were found in these combinations. Overall, compared with single drug, the drug combinations demonstrated lower bacterial concentrations. Some combinations showed bactericidal activity.ConclusionsIn S. maltophilia infections, susceptibility testing suggests that minocycline and SXT may be considered first-line therapeutic choices while tigecycline, moxifloxacin, levofloxacin, and ticarcillin-clavulanate may serve as second-line choices. Ceftazidime, colistin, and chloramphenicol show poor active against S. maltophilia. However, monotherapy is inadequate in infection management, especially in case of immunocompromised patients. Combination therapy, especially SXT plus moxifloxacin, may benefit than monotherapy in inhibiting or killing S. maltophilia.

Investigation of Antimicrobial Resistance of Stenotrophomonas maltophilia Strains Isolated from Clinical Specimens

“…Wei ve ark. 'nın (25) 2015 yılında agardilüsyon yöntemi ile yaptıkları yaptıkları bir çalışmada, levofloksasin direnci %24.7'dir. 2013 yılında Çaycı ve ark.…”

Atypical pneumonia in an immunocompromised host

“…TMP-SMX with moxifloxacin is preferred for serious infections or resistance to TMP-SMX. 7 Preventive measures to combat S. maltophilia infections includes avoidance of inappropriate use of antibiotics and regular cleaning and disinfection regimens for surfaces of medical equipment that comes in contact with fluid as respiratory therapy equipment and hemodialyzers. 8 Actinomyces naeslundii, Gram positive anaerobic bacilli, belongs to the family of the Actinomyces species which is part of normal flora of human oral cavity and GI/GU tracts.…”

Antibiotic Susceptibility of Stenotrophomonas maltophilia Isolated from Various Clinical Specimens

“…Çok merkezli başka bir çalışmada çeşitli klinik izolatlardan izole edilen S.maltophilia izolatlarına Avrupa, Kuzey Amerika, Asya ve Pasifik Bölgesinde ve Latin Amerika'da tigesiklinin en etkili antibiyotik olduğu bildirilmiştir (7) . Çin'den bildirilen çalışmada % 16.7 oranında tigesiklin direnci bildirilmiş, TMP-SXT'ye dirençli saptanan tüm suşlara tigesiklin etkili bulunmuştur (24) . Ancak 2015 yılında Fransa'da gerçekleştirilen deneysel çalışmada tigesiklin ve levofloksasinin monoterapide etkin bir ilaç olamayacağı bildirilmiştir (23) .…”

“…Özellikle riskli hasta gruplarında hayati tehdit eden enfeksiyonlarda kombinasyon tedavileri tercih edilmektedir (24) . Tigesiklinin, kolistin ve amikasinle sinerjistik etkili olduğu bildirilmiştir (18) .…”