Beijing -- China's national drug watchdog on Tuesday cited substandard disinfection as a major factor leading to the lethality of a suspect antibiotic injection, which has allegedly killed six people.

A health worker seals bottles of potentially hazardous clindamycin phosphate glucose in Loudi, Hunan Province. More than 1,300 bottles were impounded by local health authorities. [China Daily]

The "Xinfu" drug manufactured in June and July by Anhui Huayuan Worldbest Biology Pharmacy Co. wasn't sterilized properly, with both the sterilization temperature and time below the state-required safety level, said China's State Food and Drug Administration (SFDA).

"As required, the drug should go through a 30-minute disinfection process at 105 degrees Celsius. But the company lowered the temperature to 100 to 104 degrees Celsius and shortened the time to only one to four minutes," said Wang Zhexiong, an official with the safety supervision department of the SFDA.

Disinfection cabinets were also overloaded with the injection, and thus could not effectively wipe out bacteria,Wang said.

The administration promised to punish the company for its production faults and held related producers and managers accountable, but gave no details.

The administration has sent out an investigation team to inspect the pharmaceutical company in East China's Anhui Province. Test on the injection sample conducted by the team has detected excessive bacteria.

Wang said further analysis is needed to find out what kinds of bacteria the sample contains.

Earlier investigation results showed the company had produced 3.7 million bottles of clindamycin phosphate glucose injection since June, with more than 3.18 million bottles sold in 26 provinces across China.

So far, more than 1.2 million bottles of the drug had been recalled, 173,007 were en route back to the factory, and more than 403,170 bottles had been located and sealed up in other areas, said Zhang Jixiang, the administration's spokesman.

He could not account for the whereabouts of the remainder of the drug.

Sun Lei, an official in charge of market supervision with the administration, said that the remaining drug might have been used or is scattered in hospitals, clinics and drugstores in small cities and remote rural areas, making it difficult to retrieve.

The administration will continue to "comb every corner" and trace every single bottle of the drug sold by Huayuan company, he said.

The drug, which used to be a prescription medicine, had been banned by the Ministry of Health following reports of its problems, so the situation was basically under control, he said.

Since the first report of the problematic injection on July 27, the drug is blamed for killing six and causing illness to at least 80 people in 10 provinces including Zhejiang, Heilongjiang, Hunan and Shandong.