In vitro activities of quinolones, beta-lactams, tobramycin, and trimethoprim-sulfamethoxazole against nonfermentative gram-negative bacilli

Abstract

From 1991 to 1995, 8,975 nonfermentative gram-negative bacilli were isolated from patients at The Ohio State University Medical Center: 71% Pseudomonas aeruginosa, 14% Stenotrophomonas maltophilia, 7.6% Acinetobacter baumannii, and <2% each of 25 other species. The MICs of trovafloxacin (CP-99,219), ciprofloxacin, ofloxacin, ampicillin-sulbactam, piperacillin, piperacillin-tazobactam, ceftazidime, cefoperazone, ceftriaxone, imipenem, tobramycin, and trimethoprim-sulfamethoxazole (TMP-SMZ) were determined for 308 isolates, representing 13 species, by a standardized broth microdilution method. The activities of all drugs were species dependent. The fluoroquinolones had inconsistent activity against most species, although several relatively uncommon nonfermenters were consistently susceptible or resistant. Trovafloxacin was considerably more active than ciprofloxacin and ofloxacin against S. maltophilia, A. baumannii, and several less common species. Among the ␤-lactams, relative activities varied considerably; overall, imipenem had the broadest spectrum of activity but was inactive against S. maltophilia and Burkholderia cepacia isolates. Tobramycin and TMP-SMZ had stereotypic spectra of activity. Tobramycin was active against most species except S. maltophilia, Alcaligenes xylosoxidans subsp. xylosoxidans, Burkholderia spp., and Weeksella virosa. TMP-SMZ was active against most species except P. aeruginosa and Pseudomonas fluorescens-putida. A review of laboratory records indicated few changes in susceptibility patterns from 1991 to 1995; the only clear trend was toward increasing P. aeruginosa resistance to all classes of drugs.

Susceptibility of the Acinetobacter calcoaceticus–A. baumannii complex to imipenem, meropenem, sulbactam and colistin

“…In our strains, MIC 50 and MIC 90 to imipenem were high (4 and 8 mg/l, respectively), and proved similar to those observed by other authors [26,[31][32][33], although higher than those reported in many studies [23][24][25]27,[34][35][36][37][38]. However, significant discrepancies were found among the various biotypes, with noticeably lower MIC for biotypes 9 and 18 than for biotypes 1 and 2.…”

Septic shock, pneumonia, and soft tissue infection due to Myroides odoratimimus: report of a case and review of Myroides infections

“…Based on the results of sensitivity testing studies published to date in the literature, the susceptibility of M. odoratimimus to various classes of antibiotics appears to mirror that of M. odoratus, but at a lower level [24][25][26][27]. Actually, the strain isolated from our patient retained susceptibility only to carbapenems and antipseudomonal penicillins, and was resistant to all other b-lactams tested (including aztreonam), as well as to aminoglycosides, quinolones, and trimethoprim/sulfamethoxazole.…”

“…The treatment of Myroides infection is often difficult, since most strains are resistant to the b-lactams, including aztreonam and carbapenems, and exhibit variable susceptibility to aminoglycosides, quinolones, and sulfamethoxazole [24][25][26]. Based on the results of sensitivity testing studies published to date in the literature, the susceptibility of M. odoratimimus to various classes of antibiotics appears to mirror that of M. odoratus, but at a lower level [24][25][26][27].…”

Antimicrobial resistance among non-fermentative Gram-negative bacilli isolated from the respiratory tracts of Italian inpatients: a 3-year surveillance study by the Italian Epidemiological Survey

“…The respiratory tract, however, is the most common site of infection, and the incidence of these infections is on the increase (from 2.5% in 1998 to 4.1% in 1999) [30,31]. S. maltophilia is intrinsically resistant to many commonly used antimicrobial agents and rapid selection of high-level multidrug-resistant isolates in clinical strains has been observed [39,40]. S. maltophilia isolates produce a number of inducible enzymes, such as L1 (Bush group 3) zinc-dependent carbapenemase and L2 (Bush Group 2e) cephalosporinase, which hydrolyze important classes of ␤-lactams such as carbapenems and cephalosporins, respectively [41,42].…”