Hong Kong's Public Health Laboratory Services Branch of the Department of Health said Wednesday it detected a strain A/H1N1 flu virus which was resistant to oseltamivir (Tamiflu), the eighth such case in Hong Kong.

A department spokesman said the virus was identified during PHLSB's routine sensitivity tests of the A/H1N1 flu virus to oseltamivir and zanamivir.

However, he added tests showed that this strain is sensitive to zanamivir (Relenza).

The virus was isolated from the specimen taken from a 53-year-old woman who has underlying chronic disease and is on long-term immunosuppressive therapy. She developed flu-like symptoms since Jan. 16 and was admitted to the United Christian Hospital (UCH) on Jan. 19. Her nasopharyngeal aspirate specimen taken on Jan. 24 tested positive for A/H1N1 virus and was sensitive to Tamiflu. She was discharged on Jan. 24 in stable condition.

The patient was readmitted to the UCH on Jan. 28 for shortness of breath. Test results on Feb. 9 showed the virus isolated from the patient's nasopharyngeal specimen on Jan. 29 was resistant to Tamiflu but sensitive to Relenza.

The woman had been prescribed with Tamiflu during hospitalization and it is likely that Tamiflu resistance emerged during the course of drug treatment.

The spokesman said there was no evidence of further transmission of Tamiflu-resistant A/H1N1 from the patient.

The case will be reported to the World Health Organization.

According to the spokesman, more than 6,500 samples from the A/H1N1 flu patients have been tested for antiviral sensitivity in Hong Kong so far.