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Highlights from the 49th ICAAC
Newsdesk
Highlights from the 49th ICAAC The 49th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC; San Francisco, CA, USA; Sept 12–15, 2009) gave due prominence in the programme of this year’s event to the evolving pandemic of influenza A H1N1. Here we report some of the influenza-related highlights of the meeting. Nancy Cox (Centers for Disease Control and Prevention, Atlanta, GA, USA) said that the reported number of US cases of influenza-like illness is already above the seasonal baseline for the time of year. She described the situation as “unprecedented”. 97% of the influenza viruses isolated are the pandemic H1N1 strain. The rise in number of cases is particularly apparent in the southeastern USA, where school terms began earlier than in the rest of the country. Cox expects the US immunisation programme against pandemic H1N1 to begin in October, with a single dose of vaccine being sufficient to produce protective immunity among healthy adults aged 18–64 years. Jonathan McCullers (St Jude Children’s Research Hospital, Memphis, TN, USA) reported an upswing in influenza cases among children in the Memphis area. 12 children had been admitted to intensive care because of severe illness in the past 2 weeks, of
Rich Niewiroski Jr
For more on the immunisation programme in the USA see Newsdesk page 659
The 49th ICAAC was held in San Francisco
658
whom five had underlying asthma, two leukaemia, and two Staphylococcus aureus co-infection. One child has died. Among seasonal strains of H1N1 virus, 90% are resistant to oseltamivir according to Maria Zambon (Health Protection Agency, London, UK). By contrast very little resistance has been reported among isolates of pandemic H1N1. As of Sept 12, 20 confirmed cases of resistance had been reported to Roche, the manufacturer of oseltamivir, all of which are singlepoint mutations at position 275Y of neuraminidase. Resistant isolates are not linked epidemiologically, nor associated with clinical complications. Most cases are associated with use of oseltamivir for postexposure prophylaxis. Zambon noted that the possible circulation of both drugresistant and drug-sensitive strains of H1N1 might present clinicians with a treatment dilemma. In his presentation on the pandemic H1N1 influenza situation in Australia, Dominic Dwyer (Westmead Hospital, Sydney, NSW, Australia) said that, as of the time of reporting (Sept 14), 35 963 cases of influenza have been confirmed in the country. Among these cases, 4649 people needed hospital admission for severe illness and there had been 169 deaths (3·6% of those hospitalised). 14·8% of those people admitted to hospital were from Australia’s indigenous population. Even though the pandemic peak has passed in Australia, Dwyer said that the number of laboratory confirmed cases of infection was running at 10·2-times the 5 year mean for this time of year. A peak of respiratory syncytial virus activity happened simultaneously with the pandemic H1N1 peak. The median age of all patients with laboratory confirmed pandemic H1N1 influenza in Australia was 21 years. Median age of patients who needed hospital admission for severe illness was 31 years, 43 years for those needing intensive care unit (ICU) admission,
and 53 years for patients who died. The ratio of patients admitted to ICU for viral versus bacterial pneumonia was five to one. Raina MacIntyre (University of New South Wales, Sydney) revealed the results of a cluster randomised trial of N95 masks versus surgical masks or control for prevention of respiratory virus infection among health-care workers. The trial was done in Beijing, China, from December, 2008, to January, 2009, during a period of seasonal influenza activity, and involved 1936 healthcare workers from 24 hospitals. Workers, who wore N95 masks (fit tested), N95 masks (non-fit tested), surgical masks, or no masks, were followed up for development of illness during 4 weeks of mask wearing and 1 week after. Outcomes were clinical respiratory illness, influenzalike illness, any laboratory confirmed respiratory virus or bacterial infection, and laboratory confirmed influenza. By intention-to-treat analysis, surgical masks were no more effective than control for any of the clinical or laboratory outcomes. By contrast, N95 mask (fit tested or not) gave significant protection against all outcomes versus control, and were significantly more effective than surgical masks for the outcomes of clinical respiratory illness and confirmed respiratory viral or bacterial infection. Intriguingly, fit-tested N95 mask gave no more protection against clinical and laboratory outcomes than masks that had not been fit tested. MacIntyre concluded that, on the basis of the results of the trial, N95 masks “should be standard for healthcare worker protection”, and that the finding that fit testing did not improve efficacy might be an advantage for public-health control during an infectious disease emergency such as the present influenza pandemic.
John McConnell
www.thelancet.com/infection Vol 9 November 2009
Highlights from the 49th ICAAC The 49th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC; San Francisco, CA, USA; Sept 12–15, 2009) gave due prominence in the programme of this year’s event to the evolving pandemic of influenza A H1N1. Here we report some of the influenza-related highlights of the meeting. Nancy Cox (Centers for Disease Control and Prevention, Atlanta, GA, USA) said that the reported number of US cases of influenza-like illness is already above the seasonal baseline for the time of year. She described the situation as “unprecedented”. 97% of the influenza viruses isolated are the pandemic H1N1 strain. The rise in number of cases is particularly apparent in the southeastern USA, where school terms began earlier than in the rest of the country. Cox expects the US immunisation programme against pandemic H1N1 to begin in October, with a single dose of vaccine being sufficient to produce protective immunity among healthy adults aged 18–64 years. Jonathan McCullers (St Jude Children’s Research Hospital, Memphis, TN, USA) reported an upswing in influenza cases among children in the Memphis area. 12 children had been admitted to intensive care because of severe illness in the past 2 weeks, of
Rich Niewiroski Jr
For more on the immunisation programme in the USA see Newsdesk page 659
The 49th ICAAC was held in San Francisco
658
whom five had underlying asthma, two leukaemia, and two Staphylococcus aureus co-infection. One child has died. Among seasonal strains of H1N1 virus, 90% are resistant to oseltamivir according to Maria Zambon (Health Protection Agency, London, UK). By contrast very little resistance has been reported among isolates of pandemic H1N1. As of Sept 12, 20 confirmed cases of resistance had been reported to Roche, the manufacturer of oseltamivir, all of which are singlepoint mutations at position 275Y of neuraminidase. Resistant isolates are not linked epidemiologically, nor associated with clinical complications. Most cases are associated with use of oseltamivir for postexposure prophylaxis. Zambon noted that the possible circulation of both drugresistant and drug-sensitive strains of H1N1 might present clinicians with a treatment dilemma. In his presentation on the pandemic H1N1 influenza situation in Australia, Dominic Dwyer (Westmead Hospital, Sydney, NSW, Australia) said that, as of the time of reporting (Sept 14), 35 963 cases of influenza have been confirmed in the country. Among these cases, 4649 people needed hospital admission for severe illness and there had been 169 deaths (3·6% of those hospitalised). 14·8% of those people admitted to hospital were from Australia’s indigenous population. Even though the pandemic peak has passed in Australia, Dwyer said that the number of laboratory confirmed cases of infection was running at 10·2-times the 5 year mean for this time of year. A peak of respiratory syncytial virus activity happened simultaneously with the pandemic H1N1 peak. The median age of all patients with laboratory confirmed pandemic H1N1 influenza in Australia was 21 years. Median age of patients who needed hospital admission for severe illness was 31 years, 43 years for those needing intensive care unit (ICU) admission,
and 53 years for patients who died. The ratio of patients admitted to ICU for viral versus bacterial pneumonia was five to one. Raina MacIntyre (University of New South Wales, Sydney) revealed the results of a cluster randomised trial of N95 masks versus surgical masks or control for prevention of respiratory virus infection among health-care workers. The trial was done in Beijing, China, from December, 2008, to January, 2009, during a period of seasonal influenza activity, and involved 1936 healthcare workers from 24 hospitals. Workers, who wore N95 masks (fit tested), N95 masks (non-fit tested), surgical masks, or no masks, were followed up for development of illness during 4 weeks of mask wearing and 1 week after. Outcomes were clinical respiratory illness, influenzalike illness, any laboratory confirmed respiratory virus or bacterial infection, and laboratory confirmed influenza. By intention-to-treat analysis, surgical masks were no more effective than control for any of the clinical or laboratory outcomes. By contrast, N95 mask (fit tested or not) gave significant protection against all outcomes versus control, and were significantly more effective than surgical masks for the outcomes of clinical respiratory illness and confirmed respiratory viral or bacterial infection. Intriguingly, fit-tested N95 mask gave no more protection against clinical and laboratory outcomes than masks that had not been fit tested. MacIntyre concluded that, on the basis of the results of the trial, N95 masks “should be standard for healthcare worker protection”, and that the finding that fit testing did not improve efficacy might be an advantage for public-health control during an infectious disease emergency such as the present influenza pandemic.
John McConnell
www.thelancet.com/infection Vol 9 November 2009