New York, May 21 (IANS): US scientists have created a promising second-generation antibiotic to combat bacteria that are a common cause of respiratory and other infections, including the sexually transmitted gonorrhea disease.

The researchers created the promising antibiotic by changing the chemical structure of an old antibiotic named spectinomycin.

Spectinomycin is a safe, but weak drug first introduced in the 1960s, the researchers noted.

"The growing problem of drug-resistant bacteria has created an urgent need for new antibiotics that use novel mechanisms to treat adults and children worldwide," said corresponding author Richard Lee from the St. Jude Children's Research Hospital.

In this study, the scientists built on research published in the 1980s to create new, more potent versions of spectinomycin.

In the laboratory, the new spectinomycin versions blocked the growth of strains of the pneumococcal bacteria resistant to commonly used antibiotics.

Infection by pneumococcal bacteria can result in pneumonia, infection of the blood (bacteremia/sepsis), middle-ear infection or bacterial meningitis.

The second-generation spectinomycins demonstrated increased antibacterial activity against several other common causes of respiratory infection.

The spectinomycin versions were also more effective against bacteria responsible for most cases of Legionnaires' disease and the sexually transmitted diseases gonorrhea and chlamydia.

The findings appeared in the scientific journal Science Translational Medicine.