Antimicrobial Activity of Gatifloxacin Against Stenotrophomonas maltophilia and Burkholderia spp.

Abstract

Stenotrophomonas maltophilia and Burkholderia spp. are ubiquitous organisms that often establish themselves within the hospital environment and can cause devastating nosocomial infections in patients suffering from cystic fibrosis and others with compromised lung function.[1,2] These opportunistic pathogens can have multiple intrinsic and acquired resistance mechanisms, which result in reduced susceptibility to a number of drug classes. Repeated exposure to multiple drug treatment regimens and a high relapse rate after cessation of therapy leave cystic fibrosis patients particularly vulnerable to acquiring resistant phenotypes. It has been documented that the patientto-patient transfer of a single strain does occur, so the passage of a multiply resistant clone among at-risk patient populations could be potentially lethal. Because of the variably resistant nature of these species, directed therapy following culture and susceptibility testing is often critical; therefore the accuracy of the in vitro test methods remains very important. The E-test (AB Biodisk, Solna, Sweden) and the standardised disk diffusion method are easily adapted to most laboratory settings, and it is possible to select only those drugs, or a representative of a drug class, that will provide a physician with the treatment options of greatest interest. Gatifloxacin is a new 8-methoxy fluoroquinolone which, like many recently evaluated quinolones, has a broadened spectrum of activity for Gram-positive organisms and anaerobes.[3] Because multiply resistant isolates of S. maltophilia and Burkholderia spp. are common among chronically ill patients, fluoroquinolone therapy is becoming increasingly popular. This study focused on the activity of gatifloxacin and other fluoroquinolones – ciprofloxacin, levofloxacin, ofloxacin, sparfloxacin and trovafloxacin – against S. maltophilia, B. cepacia and B. pickettii isolates. The disk diffusion and E-test methods were evaluated in comparison to a reference dilution method.