, a drug development startup targeting drug-resistant infections, has some new investors and a whopping $46 million in the bank after closing on a “C” round of venture financing.

“This is a big amount of money at any time, let alone now,” said a spokesperson for in Durham, which participated in the round.

“Sadly, this is a huge market opportunity,” she added. “We have been an investor from the beginning. The management team is really strong, and they know how to execute on these clinical trials.”

To date, Cempra has raised $78 million.

The company has proprietary chemistry technology related to macrolides, which are antibiotics that fight a wide range of bacterial infections. The firm’s founders have backgrounds in discovering and developing anti-infective treatments. Cempra has already licensed a pipeline of macrolides and ketolides, which are effective against macrolide-resistant bacteria, from Optimer Pharmaceuticals in San Diego, CA.

The global market for anti-infective drugs is estimated to be greater than $30 billion, according to Cempra.

Cempra launched in January 2007. It has two drugs in clinical trials.

“This additional funding represents strong confidence in our approach to address the need for new antibiotics, particularly those that will be used to treat drug-resistant infections, and it will help us advance our clinical development of these very promising compounds," said Prabhavathi Fernandes, Cempra’s chief executive officer.

“The Infectious Disease Society of America has cited that the top three needs in antibacterials are treatments for multi-drug resistant pneumococcus, MRSA, and gram negative pathogens,” Fernandes added. “With CEM-101 potentially indicated for community-acquired bacterial pneumonia, and CEM-102 being developed for complicated skin infections, including MRSA, we are making great strides to address two of those three needs.”

Cempra plans to use the new funds for the trials of CEM-101, its lead product, and CEM-102, which is in early-stage development. Cempra is researching other compounds.

“It’s encouraging to see that even in the current economic environment, a company like Cempra, with an innovative approach and promising compounds, can attract strong investors that enable it to deliver on its mission to serve the global patient population,” said Garheng Kong, a general partner at Intersouth who also is chair of the Cempra board.

led the round as a new investor, and Geeta Vemuri of the firm will join the Cempra board.

Also joining the investment syndicate as a new partner is

Existing investors other than Intersouth that participated were Aisling Capital, Teachers’ Private Capital and Wistar Morris III, an investment banker.

In a statement, Vemuri said Quaker BioVentures believes Cempra is on target with needed antibiotics.

"Antibiotic resistance is an increasingly daunting major public health challenge, and Quaker is committed to supporting companies that are advancing the most promising solutions,” Vemuri said. "With two compounds in active clinical development, Cempra addresses a critical, growing need for novel and potent antibiotics. We are excited to help the company continue to rapidly build a leading position in this field.”