On Tue 27 Oct 2009, the Pandemic (H1N1) Central Epidemic Command Center of Taipei announced the detection of another [isolate] of pandemic (H1N1) 2009 virus which was resistant to oseltamivir. A summary of epidemiological and laboratory investigation results is outlined below.
The oseltamivir-resistant pandemic (H1N1) 2009 virus was isolated from a specimen taken from a 44-year-old man living in northern Taiwan. On Thu 27 Aug 2009 the patient experienced general malaise and got fever next day. He visited the local medical clinic for medications. He was tested with an influenza rapid test and the result was influenza A virus positive. He began a 5-day course of oseltamivir. On the night of 2 Sep 2009, he experienced fever and cough again. Next day, he visited an ER [Emergency Room] and his chest X-ray revealed pneumonia. He was admitted for further diagnosis and treatment. On 3 Sep 2009, he tested positive for pandemic (H1N1) 2009 virus by real-time reverse transcription polymerase chain reaction (rtRT-PCR). Nevertheless, he was discharged upon recovery on 7 Sep 2009.
The National Influenza Center (NIC) in Taipei conducted routine antiviral resistance tests on specimens taken from confirmed patients with pandemic (H1N1) 2009. Nucleotide sequencing of the NA [neuraminidase] gene confirmed the presence of the H275Y mutation in the virus isolated from the sample collected on 3 Sep 2009, indicating resistance to oseltamivir, but not to zanammivir.
The virus, isolated from a patient with documented exposure to oseltamivir treatment, is the 2nd case of oseltamivir-resistant strain among 339 isolates tested in Taipei since 1 Jun 2009. Investigations have not found the resistant virus in close contacts [o patients harbouring oseltamivir-resistant virus]. Therefore, the patient represents a sporadic case of oseltamivir resistance. The public and the media were informed of the findings on Tue 27 Oct 2009.
