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Volume 2 No 05 ; 1 February 2008

 

 

Publication of MRSA bacteraemia and Clostridium difficile infection data

The latest Healthcare Associated Infections quarterly report was published on 30 January. This includes new quarterly data for both MRSA bacteraemia and C. difficile infection, and six-monthly data for MRSA bacteraemia, collected through the mandatory surveillance systems. These data are available, together with commentaries and historical annual data, at http://www.hpa.org.uk/infections/topics_az/hai/Mandatory_Results.htm.

MRSA bacteraemia

In the six-month period April – September 2007, 2,376 episodes of MRSA bacteraemia were reported by NHS acute Trusts in England . The national rate of MRSA bacteraemia during this period was 1.24 cases per 10,000 bed-days. This compares to a rate of 1.57 cases per 10,000 bed-days in October 2006 – March 2007, and 1.77 cases per 10,000 bed-days in April – September 2006.

Quarterly data show that there were 1,304 episodes of MRSA bacteraemia in April – June and 1,072 in July – September. This continues the quarter-on-quarter decrease seen since April 2006.

Clostridium difficile

During the quarter July – September 2007, there were 10,734 episodes of C. difficile infection in patients aged 65 years and over. This represents a decrease of 21% on the previous quarter and a decrease of 16% from the same period in 2006.

Data on C. difficile infections in patients aged 2-64 years were published for the second time this week (until April 2007, the mandatory surveillance scheme only included patients aged 65 years and over). In July – September 2007, there were 2,496 episodes of infection in this younger age group.

Trusts are required to report all C. difficile positive diarrhoeal specimens processed by their laboratories, including samples taken in the community (e.g. at GP surgeries, nursing homes and PCT hospitals). For the first time, data representing specimens taken in acute and other settings are presented separately. This does not necessarily reflect where the infection was acquired, but does give an indication of the burden of community-diagnosed infection.

The data should be interpreted with care as the mandatory C. difficile surveillance system has recently undergone significant changes which may influence ascertainment. Trusts have been given an opportunity to revise their data in accordance with a changed case definition; the data published today are therefore subject to change. Further information about these changes to the reporting requirements is available at:
http://www.dh.gov.uk/en/Publicationsandstatistics/Lettersandcirculars
/Professionalletters/Chiefmedicalofficerletters/DH_082107

Emergence of resistance to oseltamivir among influenza A(H1N1) viruses in Europe

Surveillance of antiviral drug susceptibility of current influenza viruses circulating in Europe has shown that a proportion, approximately 14%, of the A(H1N1) viruses tested are resistant to oseltamivir but retain sensitivity to zanamivir and amantadine/rimantadine. This is not evenly distributed across Europe and is restricted to nine European countries. Influenza A(H1N1) is currently the predominant influenza virus in Europe .

So far 437 influenza A(H1N1) viruses isolated between November 2007 and January 2008 from 18 European countries have been tested and 59 (14%) isolates have been found to have a mutation, H247Y on the neuraminidase, which confers high resistance to oseltamivir. Eight of 162 (5%) United Kingdom isolates have been found to have oseltamivir resistance compared to 26 of 37 Norwegian isolates (70%), two of six (33%) Portuguese isolates, two of seven (28%) Finnish isolates and 15 of 87 (17%) French isolates. These findings are in marked contrast to the previous winter seasons of 2004/2005, 2005/2006, and 2006/2007, when oseltamivir resistance was detected in <1% of circulating strains from 24 countries.

More extensive surveillance within Europe and in other parts of the world is required to establish the relative prevalence and geographical distribution of these resistant viruses, and to evaluate their potential impact on the effectiveness of drug use. The spectrum of clinical illness associated with infection by oseltamivir-resistant viruses remains to be fully determined, although limited information from initial clinical cases does not suggest unusual disease syndromes. Determining the origins and genesis of these drug-resistant strains, which appear to have emerged in regions of the world where there is little drug pressure, will be important in understanding the emergence and persistence of oseltamivir resistance in relation to the evolution of influenza viruses and drug use.

Adapted from:
Lackenby A, Hungnes O, Dudman SG, Meijer A, Paget WJ, Hay AJ, Zambon MC. Emergence of resistance to oseltamivir among influenza A(H1N1) viruses in Europe . Euro Surveill 2008;13(5). Available at: http://www.eurosurveillance.org/edition/v13n05/080131_2.asp

For further information:
Observed oseltamivir resistance in seasonal influenza viruses in Europe interpretation and potential implications. Euro Surveill 2008;13(5). Available at: http://www.eurosurveillance.org/edition/v13n05/080131_1.asp