A changing pattern of susceptibility of Xanthomonas maltophilia to antimicrobial agents: implications for therapy

Abstract

The in vitro susceptibilities of 130 Xanthomonas maltophilia isolates to 12 antibiotics-trimethoprimsulfamethoxazole, minocycline, ticarcillin-clavulanate, ceftazidime, cefoperazone, cefoperazone-sulbactam, imipenem, ciprofloxacin, and the investigational quinolones PD 117558, PD 117596, PD 127391, and sparfloxacin-were determined by a microtiter broth dilution technique. Other than the investigational quinolones, the most active antibiotics were minocycline, trimethoprim-sulfamethoxazole, and ticarcillinclavulanate, in order. However, the first two were not bactericidal, while about half of the isolates exhibited intermediate susceptibility to ticarcillin-clavulanate. Patterns of susceptibility to trimethoprim-sulfamethoxazole and ciprofloxacin relative to the years of isolation of these strains reflected the development of resistance to the antibiotic prophylaxis practices in the hospital. We recommend that a combination of antibiotics, such as trimethoprim-sulfamethoxazole, minocycline, and ticarcillin-clavulanate, at or close to the maximum tolerated doses be used in the treatment of serious X. maltophilia infections.Xanthomonas maltophilia has emerged as a significant cause of morbidity and mortality in cancer patients (5,6,18). This organism is capable of causing life-threatening infections (5, 25) and is usually resistant to multiple antimicrobial agents, particularly to those of the beta-lactam class (25). The standard therapy for infections by this organism is trimethoprimsulfamethoxazole. The newly developed quinolones, which have broad antimicrobial activity, are now being used in both prophylaxis and therapy of infections in cancer patients. However, at The University of Texas M. D. Anderson Cancer Center, we have cared for patients with serious X maltophilia infections that developed during quinolone prophylaxis. Because of our concern for the emergence of resistance of X. maltophilia to quinolones and the limited therapeutic options available to treat this potentially life-threatening infection, we studied the in vitro activities of various antimicrobial agents, including quinolones, against 130 clinical isolates of X. maltophilia.The strains of X maltophilia used in this study were single patient isolates from the clinical microbiology laboratory at M. D. Anderson Cancer Center. Eighty-nine of the cultures were isolated from patients' bloodstreams, 24 were from urine, 12 were from sputum or the throat, and 5 were from miscellaneous sources. These isolates had been collected in the infectious disease laboratories since 1981 for their clinical significance. The bacteria were identified as X. maltophilia by various biochemical tests using the API 20C system (Analytab Products, Plainview, N.Y.). Organisms were stored in the laboratory at -70°C.All antimicrobial agents were obtained in the form of standard laboratory powders and were stored at -70°C before use. The drugs tested were trimethoprim-sulfamethoxazole (Hoffmann-La Roche, Montclair, N.J.); minocycline (Lederle, Pearl River, N.Y.); ciprofloxac...

Two Episodes of Stenotrophomonas maltophilia Endocarditis of Prosthetic Mitral Valve: Report of a Case and Review of the Literature

“…Favorable outcome with antimicrobial therapy alone has been reported (15) and surgery to replace the infected valve may be necessary (16). In reviewing of the literature, only 15 of 24 (63%) patients An important clinical aspect of S. maltophilia is its difficulty to treat due to the resistance nature of the organism (17). Most strains of S. maltophilia are resistant to -lactam agents due to two mechanisms, low outer membrane permeability and constitutive overproduction of -lactamases (18,19).…”

Novel Mechanism of Hydrolysis of Therapeutic β-Lactams byStenotrophomonas maltophilia L1 Metallo-β-lactamase

“…It is intrinsically resistant to a wide range of antibiotics and in clinical strains may possess additional high level multidrug resistance (21). Resistance of this organism to a wide range of ␤-lactam antibiotics is due primarily to expression of a pair of chromosomal ␤-lactamases, a class A active-site serine enzyme L2 (22), and a metallo-␤-lactamase L1 (23). The L1 enzyme is the prototypical member of a distinct subclass (B3) of metallo-␤-lactamases that diverge markedly in sequence from the better characterized enzymes, such as BCII and CcrA (24,25).…”

Disseminated Soft Tissue Infection and Sepsis with Stenotrophomonas maltophilia in a Bone Marrow Transplant Patient

“…Prolonged neutropenia and antimicrobial use in this patient and the clinical presentation are consistent with this newly described syndrome. Of interest, imipenem was not employed in this patient initially; however, ceftazidime and ciprofloxacin both were used, and other recent reports suggest that they are risk factors for subsequent stenotropamonas infection (6,9). This patient initially received cotrimoxazole as prophylaxis, the drug of choice for the treatment of S maltophilia infections, but for the four weeks before the stenotrophomonas bacteremia she had not been on cotrimoxazole.…”