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CIDRAP NEWS SCAN: Antibiotics after mastectomy; Southern Hemisphere flu vaccine picks; Nipah virus in India

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  • CIDRAP NEWS SCAN: Antibiotics after mastectomy; Southern Hemisphere flu vaccine picks; Nipah virus in India


    News Scan for Sep 27, 2021
    Antibiotics after mastectomy; Southern Hemisphere flu vaccine picks; Nipah virus in India
    Filed Under:
    Nipah; Antimicrobial Stewardship; Influenza Vaccines

    Antibiotics after mastectomy common, but with small benefit, study finds

    An analysis of US health insurance data found that post-discharge prophylactic antibiotics are commonly prescribed after mastectomy, but provide only a small reduction in surgical-site infections (SSIs), researchers reported today in Infection Control & Hospital Epidemiology.
    Using a database that includes outpatient pharmacy claims for individuals covered by employer-sponsored and commercial health insurance plans, researchers from the Washington University School of Medicine in St. Louis studied a cohort of women ages 18 to 64 who underwent mastectomy from January 2010 through June 2015. Their aim was to investigate the factors associated with post-discharge prophylactic antibiotic use and the impact on SSIs.
    Out of 38,793 mastectomies, 24,818 included immediate reconstruction. Prophylactic antibiotics were prescribed after discharge after 2,688 mastectomy-only procedures (19.2%) and after 17,807 mastectomies with immediate reconstruction (71.8%). Post-discharge prophylactic antibiotic use ranged from 18.9% in 2013 to 19.7% in 2015 after mastectomy only and 68.2% in 2010 to 74.4% in 2015 after mastectomy with immediate reconstruction. Factors associated with post-discharge antibiotics included history of Staphylococcus aureus infection, neoadjuvant chemotherapy, non-infectious wound complication during the mastectomy admission, and implant reconstruction, but physician preference appeared to be a bigger factor.
    The 90-day incidence of SSI after mastectomy was 3.5% after mastectomy only and 8.8% after mastectomy with immediate reconstruction. Antibiotics with anti–methicillin-sensitive S aureus (MSSA) activity were the most commonly prescribed antibiotics after mastectomy and were associated with decreased SSI risk after mastectomy only (adjusted relative risk [aRR], 0.74; 95% confidence interval [CI], 0.55 to 0.99) and mastectomy with immediate reconstruction (aRR, 0.80; 95% CI, 0.73 to 0.88), respectively. The numbers needed to treat to prevent 1 additional SSI were 107 and 48, respectively.
    The authors note that anti-MSSA antibiotics are associated with moderate risk of Clostridioides difficile infection and other adverse events, ranging from rashes to more severe events, including anaphylaxis and acute renal failure.
    "The small apparent benefit of post-discharge oral antibiotics should be balanced with the risks associated with overuse of antibiotics, particularly given the relatively large number of women who would need to be treated to prevent one infection," they write.
    Sep 27 Infect Control Hosp Epidemiol abstract

    WHO advisors switch 2 strains for Southern Hemisphere 2022 flu season

    Last week the World Health Organization (WHO) flu vaccine advisors met to recommend the strains to include in the Southern Hemisphere's 2022-season flu vaccines, which swaps out two strains compared with the current season's vaccines.
    For both egg- and cell-based vaccines, the advisors recommend replacing the H3N2 component, switching from influenza A/Hong Kong/2671/2019 and A/Hong Kong/45/2019-like viruses, respectively, to influenza A/Darwin/9/2021-like and A/Darwin/6/2021-like viruses, respectively. The WHO notes that it sometimes recommends different viruses for the different production systems, because flu viruses don't always replicate equally well among the egg- and cell-based systems.
    Also, for both production systems, the WHO recommends swapping out the influenza B/Victoria lineage component, replacing the influenza B/Washington/2/2019-like virus with B/Austria/1359417/2021-like virus. The team also recommended that trivalent (three-strain) vaccines contain Victoria as the influenza B lineage vaccine virus.
    For comparison, Northern Hemisphere flu vaccines for the current season—recommended by the group in February—will contain two strains that are different from the Southern Hemisphere's upcoming vaccine. One is the H3N2 component, an influenza A/Cambodia/e0826360/2020-like virus for both production systems, and for the influenza B Victoria lineage, an influenza B/Washington/02/2019-like virus, also for both production systems.
    The WHO flu surveillance in many countries has recovered from COVID-related disruptions, and though more clinical specimens were tested in 2021 than in 2020, flu detections were vastly reduced, with few viruses available for analysis.
    Sep 24 WHO recommendations
    Sep 24 WHO Q and A

    WHO fleshes out details of India's recent Nipah virus case

    Earlier this month India reported a fatal Nipah virus case involving a boy from the Kozhikode district in Kerala state, and late last week the WHO weighed in with more details.
    The 12-year-old boy's symptoms began in Aug 29, and after his illness got worse despite care at local health facilities, he was hospitalized on Aug 31. When his condition deteriorated, the family requested a transfer to another hospital, where specimens were collected and sent to the National Institute of Virology in Pune, where tests confirmed Nipah virus on Sep 4. The boy died on Sep 5, and he was cremated and buried safely in Kozhikode the same day.
    Investigators have identified contacts, including healthcare workers and family members, who were placed in quarantine.
    The WHO said the boy's illness is the only case detected, and the event occurred in a rural area of Kerala state, located in southern India, where an outbreak occurred in 2018. Fruit bats were identified as the likely source of that outbreak. The WHO said the national and regional risks from the recent case are both low.
    Nipah virus disease is an emerging zoonotic threat, with the virus spreads through direct contact with infected animals, contaminated food products, or close contact with infected people. It has a high fatality rate, and there are no approved treatments or vaccines, though monoclonal antibodies have been developed and are sometimes available under compassionate use.
    Sep 24 WHO statement
    Sep 7 CIDRAP News scan