Identification and antimicrobial susceptibility testing of clinical isolates of nonfermenting gram-negative bacteria by the Phoenix Automated Microbiology System.
The Phoenix Automated Microbiology System (Becton Dickinson, Sparks, MD) was evaluated for its ability to identify nonfermenting gram-negative pathogens and measure their drug susceptibility. Isolates producing rare extended-spectrum beta-lactamases (PER-1, IMP-2, VIM-1, and VIM-2) were included in the study. Species identification was compared to that given by the ATB System (bio-Mérieux, Marcy l'Etoile, France), whereas susceptibility results were compared to those produced by a reference broth microdilution test (panels manufactured by Pasco Laboratories, Becton Dickinson). The Phoenix system consistently identified all isolates of Pseudomonas aeruginosa (n = 55) and Stenotrophomonas maltophilia (n = 28), while in other cases species agreement was obtained for 47/53 isolates (Acinetobacter baumannii, 29/31; Pseudomonas putida, 10/11; Burkholderia cepacia, 6/7; and Pseudomonas fluorescens, 2/4). Overall, the Phoenix and ATB systems gave equal results in 130/136 cases (95.6%). For two isolates, consistent identification was obtained at the genus level, thus bringing the cumulative agreement to 97.1%. MIC values (interpreted according to NCCLS guidelines) gave essential and categorical agreement in 94.2% and 93.1% of cases, respectively. Minor and major errors were 5.1% and 5.2%, respectively. No very major errors were produced. The mean time to results (TTR) for the Phoenix system was 14.8 +/- 1.6 h (mean +/- SD), with the shortest TTR being observedfor A. baumannii (13.0 +/- 1.8 h) and the longest one for P. aeruginosa (15.6 +/- 1.2 h). In conclusion, the Phoenix system performed rapidly and correctly in the identification of clinical isolates of important opportunistic pathogens and in measuring their susceptibility to antipseudomonal drugs.
Endimiani
A
A
Laboratory of Microbiology, Ospedale di Circolo, University of Insubria, Varese, Italy.
Luzzaro
F
F
Tamborini
A
A
Lombardi
G
G
Elia
V
V
Belloni
R
R
Toniolo
A
A
D001331:Automation; D015373:Bacterial Typing Techniques / Q000379:methods*; D006090:Gram-Negative Bacteria / Q000145:classification* / Q000187:drug effects*; D016905:Gram-Negative Bacterial Infections / Q000382:microbiology; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods*