CORRECTED - UPDATE 3-Targanta drug seen similar to rivals-FDA

(Corrects paragraphs two and five to clearly describe comparison drugs and to show that ViroPharma's oral vancomycin is used for a different purpose and is not a rival to the Targanta drug)

(Updates shares to close, adds drug details)

By Susan Heavey

NEW YORK, Nov 17 (Reuters) - Targanta Therapeutics Corp's TARG.O clinical trial data show its antibiotic is about as safe and effective as current treatments, Food and Drug Administration staff said on Monday, sending the company's shares up as much as 42 percent.

In general, the results found patients given Targanta's oritavancin fare as well as those given the older injectable antibiotic vancomycin as well as oral cephalexin, FDA staff said in documents released ahead of an advisory committee meeting on Wednesday.

The company is seeking FDA approval to sell its drug under the name Nuvocid for adults with complicated skin infections from a variety of bacteria, including some resistant to other antibiotics such as vancomycin.

While Targanta's injectable drug works similarly to current medications, new antibiotics are needed to combat infections as more bacteria mutate and develop a resistance, the Cambridge, Massachusetts-based drugmaker said in separate documents also released on Monday.

Vancomycin is sold in a variety of forms by various makers, including as a generic injectable product. It is also sold as a pill called Vancocin by ViroPharma Inc (VPHM.O) under license from Eli Lilly and Co (LLY.N), mainly to treat two infections of the lower digestive tract.

Cephalexin is also sold in various forms, including Keflex by Middlebrook Pharmaceuticals Inc (MBRK.O), among other brands.

"To date, no oritavancin-resistant strains have emerged in clinical trials," it said.

If left untreated or not properly treated, serious skin infections can worsen enough to cause tissue removal or amputation, the company said, saying oritavancin is a safe and effective alternative.

In its review, FDA staffers said the data showed Targanta's antibiotic was as effective as drugs used now.

"In general, the outcomes ... were comparable," when broken down to look at various disease categories, as well as age, gender and other groups, the staffers wrote in regard to the drug's effectiveness.

Oritavancin also appeared about as safe as its older rivals, the FDA also said.

Although there were 74 reported deaths in all the clinical trials among patients taking either oritavancin or vancomycin, most cases appeared related to the patients' medical condition and not treatment, the FDA staff said.

In one study, 16 patients given oritavancin died compared with nine given vancomycin -- a rate "comparable for both treatment groups," the FDA wrote.