Distribution of resistant gram-positive organisms across the census regions of the United States and in vitro activity of tigecycline, a new glycylcycline antimicrobial.
BACKGROUND
Gram-positive isolates were collected from 76 medical centers within the 9 census regions across the United States.


METHODS
Antimicrobial susceptibilities were determined according to Clinical and Laboratory Standards Institute guidelines.


RESULTS
Vancomycin resistance among Enterococcus faecium isolates varied from 45.5% (New England) to 85.3% (East South Central). The lowest concentrations at which 90% of the isolates were inhibited (MIC90) were for tigecycline (0.06-0.12 microg/mL) and for linezolid (2-4 microg/mL). Methicillin-resistant Staphylococcus aureus (MRSA) varied from 27.4% (New England) to 62.4% (East South Central). All MRSA were susceptible to tigecycline, linezolid, and vancomycin. Penicillin-nonsusceptible Streptococcus pneumoniae ranged from 23.3% in the Pacific region to 54.5% in the East South Central region. Tigecycline, imipenem, levofloxacin, linezolid, and vancomycin all maintained MIC90 of < or =1 microg/mL against penicillin-nonsusceptible S pneumoniae in vitro, irrespective of region.


CONCLUSIONS
This study demonstrates the variable rate of antimicrobial-resistant gram-positive organisms in the United States. Tigecycline may make a useful addition to the antimicrobial armamentarium.
Denys
Gerald A
GA
Clarian Health Partners, Inc., Indianapolis, Indiana 46202, USA. gdenys@clarian.org
Koch
Kim M
KM
Dowzicky
Michael J
MJ
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D024901:Drug Resistance, Multiple, Bacterial; D006094:Gram-Positive Bacteria / Q000187:drug effects*; D016908:Gram-Positive Bacterial Infections / Q000188:drug therapy; D006801:Humans; D016106:Methicillin Resistance; D008826:Microbial Sensitivity Tests; D008911:Minocycline / Q000031:analogs & derivatives* / Q000494:pharmacology; D018571:Sentinel Surveillance; D000078304:Tigecycline; D014481:United States / Q000453:epidemiology; D020713:Vancomycin Resistance
D000900:Anti-Bacterial Agents; D000078304:Tigecycline; D008911:Minocycline