Multicenter study to assess the in vitro activity of tigecycline by disk diffusion test against clinical isolates from Argentina.
BACKGROUND
Tigecycline is a new antibiotic currently used in healthcare environments where multidrug resistance is prominent. Because there is a constant potential for resistance to emerge, survey studies are needed.


METHODS
Isolates collected in 20 clinical laboratories from 4 states of Argentina between November 2005 and October 2006 were tested using the disk diffusion method as described by the CLSI.


RESULTS
A total of 3,182 isolates were assessed. Gram-positive cocci represented 43.4% of the total isolates [Staphylococcus aureus (878), coagulase-negative staphylococci (255), Enterococcus spp. (201), Streptococcus spp. (47)], Enterobacteriaceae 39.6% and Acinetobacter spp. 11.1%. Tigecycline proved equally active against methicillin-resistant and methicillin-susceptible staphylococci, as well as against vancomycin-resistant and vancomycin-susceptible enterococci (100% of susceptibility for all Gram-positive bacteria tested). Tigecycline susceptibility for Enterobacteriaceae, other than Proteeae tribe and Serratia spp., ranged from 88 to 100%, including against strains with resistance to third-generation cephalosporins with phenotype of extended spectrum beta-lactamases (extended spectrum beta-lactamase-positive Escherichia coli 17.7% and extended spectrum beta-lactamase-positive Klebsiella pneumoniae 50.5%). Adopting a resistant breakpoint of 16 mm, 92% of the Acinetobacter isolates were susceptible to tigecycline.


CONCLUSIONS
Tigecycline was active against a wide variety of bacterial species, including most of the multidrug-resistant Gram-negative and Gram-positive bacteria. Therefore, it could be a suitable option in the treatment of infections caused by these organisms in hospitalized patients.
Fernández Canigia
Liliana
L
Reference Laboratory, Hospital Alemán, Pueyrredón 1640, Buenos Aires, Argentina. lfcanigia@labdl.com.ar
Kaufman
Sara
S
Lanata
Liliana
L
Vay
Carlos
C
Giovanakis
Marta
M
Bantar
Carlos
C
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001118:Argentina; D052978:Disk Diffusion Antimicrobial Tests; D024881:Drug Resistance, Bacterial; D018432:Drug Resistance, Multiple; D006090:Gram-Negative Bacteria / Q000187:drug effects / Q000302:isolation & purification; D006094:Gram-Positive Bacteria / Q000187:drug effects / Q000302:isolation & purification; D006801:Humans; D008911:Minocycline / Q000031:analogs & derivatives* / Q000494:pharmacology; D000078304:Tigecycline
D000900:Anti-Bacterial Agents; D000078304:Tigecycline; D008911:Minocycline