Wyeth Pharmaceuticals data from multiple studies that indicate the in vitro activity of Tygacil (tigecycline) against many resistant gram-negative bacteria, including Extended-Spectrum Beta-Lactamase (ESBL)-producing organisms showed that nearly 99 per cent of acinetobacter isolates tested were susceptible to Tygacil.

"While much has been reported on the rising rates of gram-positive organisms, such as methicillin -resistant Staphylococcus aureus (MRSA), there is increasing concern throughout the global medical community over resistant gram-negative organisms, especially those that are ESBL producing," said David Wu, assistant vice president, clinical affairs, global medical affairs, Wyeth.

Extended-Spectrum Beta Lactamases, known as ESBLs, are enzymes produced by Gram-negative bacteria that make the organisms drug resistant. Tigecycline is not affected by these enzymes.

Among the data presented are results from the Tigecycline Evaluation Surveillance Trial (T.E.S.T.) demonstrating tigecycline's in vitro activity against commonly encountered Gram-negative bacteria strains, such as Acinetobacter baumannii, that are found in certain community- and hospital- acquired infections. Other data demonstrated tigecycline's in vitro activity against important ESBL-producing bacteria such as Klebsiella pneumoniae and Escherichia coli isolates, claims a Wyeth release.

Data have shown a marked rise in resistant strains of gram-negative bacteria such as Klebsiella, Enterobacter, and E. coli over the past decade. A high rate of ESBL-producing gram-negative bacteria has been detected in Latin America, and, since 2001, ESBL production has risen sharply in the UK and Ireland. According to data from the Centres for Disease Control and Prevention, Klebsiella pneumoniae isolates resistant to certain antibiotics have increased in the US within the past few years.

Tygacil, a first-in-class glycylcycline, is an I.V. antibiotic with an expanded broad spectrum of in vitro activity against gram positives, gram negatives, anaerobes, methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE); TYGACIL is unaffected by Extended- Spectrum Beta Lactamases (ESBLs).

Wyeth is one of the world's largest research-driven pharmaceutical and health care products companies.