Factors associated with relative rates of antibiotic resistance in Pseudomonas aeruginosa isolates tested in clinical laboratories in the United States from 1999 to 2002.

For the period from 1999 to 2002 in the United States, the in vitro susceptibilities of 52,637 Pseudomonas aeruginosa isolates to 10 antimicrobial agents were evaluated. The isolates were from 29 laboratories, 11 of which participated in The Surveillance Network for four consecutive years. Isolates were collected from adult patients (> or =18 years of age) in intensive care units (ICU), non-ICU inpatients, nursing home patients, and outpatients; data were analyzed to evaluate factors, such as year of isolation, patient age group, isolate specimen source, and patient type (hospitalized patients [ICU, non-ICU, or nursing home] or outpatients). Rates of resistance for the 4-year period were highest for isolates from patients in ICU and 18- to 39-year-old patients and for isolates from the lower respiratory tract. Resistance decreased with age. Resistance was lowest in isolates from outpatients, in isolates from > or =70-year-old patients, and from specimens from the upper respiratory tract. Multidrug resistance (MDR) (resistance to three or more antimicrobial agents) accounted for 24.9% of all isolates. The MDR rate was highest in isolates from patients in nursing homes (29.9%) and ICU (29.5%).

Comparison of four antimicrobial susceptibility testing methods to determine the in vitro activities of piperacillin and piperacillin-tazobactam against clinical isolates of Enterobacteriaceae and Pseudomonas aeruginosa.

Susceptibility to piperacillin was similar to that to piperacillin-tazobactam (<1% difference) for 6,938 isolates of Enterobacter aerogenes and 13,954 isolates of Enterobacter cloacae tested using a Vitek system; for the same species, in contrast, susceptibility rates to piperacillin-tazobactam were 5.9 to 13.9% higher than to piperacillin using disk diffusion, MicroScan, and Vitek 2 testing. Unprecedented phenotypes (piperacillin susceptible and piperacillin-tazobactam intermediate; piperacillin intermediate and piperacillin-tazobactam resistant; piperacillin susceptible and piperacillin-tazobactam resistant) accounted for 6.1% of the results for E. aerogenes isolates and 6.0% of the results for E. cloacae isolates tested with the Vitek system.

In vitro antibacterial activity of the peptide deformylase inhibitor BB-83698.

OBJECTIVES: BB-83698 is a peptide deformylase inhibitor currently in clinical trials in Europe. The purpose of this study was to provide additional susceptibility data from clinical isolates, including drug-resistant strains. METHODS: The in vitro activities of BB-83698 and comparators were determined against 281 streptococci, 154 Staphylococcus aureus, 110 Haemophilus influenzae and 50 Moraxella catarrhalis strains selected for their resistance phenotypes. Broth microdilution MICs and MBCs were determined according to NCCLS guidelines. RESULTS: The MIC90s were 0.25-0.5 mg/L for S. pneumoniae, including penicillin-, erythromycin-, levofloxacin- and multidrug-resistant strains. The MIC90s for Streptococcus pyogenes and Streptococcus agalactiae were 0.12 mg/L and for viridans streptococci, the MIC90 was 0.5 mg/L. Against S. aureus, including oxacillin- and levofloxacin-resistant strains, and vancomycin-intermediate strains, the MIC90 was 8 mg/L. Against beta-lactamase-negative and -positive H. influenzae, the MIC90s were 32 and 64 mg/L, respectively, and against both beta-lactamase-negative and -positive M. catarrhalis the MIC90 was 0.12 mg/L. In MBC studies, the ratio of MBC/MIC was 1:1 or 2:1 against 31% of S. pneumoniae, 33% of S. aureus, 63% of H. influenzae and 9% of M. catarrhalis. CONCLUSIONS: Although BB-83698 has reduced in vitro activity against H. influenzae, it is a potent antimicrobial with excellent activity against streptococci and Moraxella.