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Influenza an important risk factor for aspergillosis coinfection

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January 25, 2019

Patients with influenza who received steroids after ICU admission, have a white blood count greater than 10 x 109/L on ICU admission, and have multiple nodules and cavities detected via CT imaging are at a higher risk for developing invasive pulmonary aspergillosis coinfection.

Writing in the Clinical Respiratory Journal, Linna Huang, MD, from the department of pulmonary and critical care medicine at China-Japan Friendship Hospital’s Centre for Respiratory Disease, and colleagues noted that although coinfection as a complication of influenza has been “well described,” a coinfection with invasive Aspergillus has “typically been ignored.”

“Influenza may represent a novel host risk factor for this invasive fungal infection,” they wrote. “Meanwhile, the mortality rate among coinfected patients has been found to be approximately 50% to 60%, which is approximately five times that of hospitalized patients with influenza alone.”

Huang and colleagues conducted a retrospective study that included 64 critically ill patients with confirmed influenza who were admitted to the China-Japan Friendship Hospital’s ICU during the 2017-2018 influenza season, and 45 coinfected patients found through a search of PubMed and Medline for papers published about influenza and invasive pulmonary aspergillosis (IPA) coinfection from January 2009 to March 2018.

When the researchers assessed only the 64 patients admitted to the hospital during the 2017-2018 influenza season, they discovered a 28.1% (n = 18) incidence of IPA coinfection. According to the study, 55.6% of those patients had underlying diseases, 5.6% had a history of immunosuppressant use, 44.4% reported steroid use in the last month, 55.7% required rescue ventilation strategies, and 22.2% required extracorporeal membrane oxygenation. The average age of these patients was 52 years.

To compare the outcomes of coinfected and non-coinfected patients, the researchers added 45 patients, found in the literature, to the initial 18, which resulted in 63 patients assigned to the IPA group and 46 patients who were admitted to the ICU with influenza but had no coinfection to the control group.

Huang and colleagues discovered that a higher risk for developing IPA was associated with receiving steroids after ICU admission, a WBC of more than 10 x 109/L upon admission to the ICU, and the detection of multiple nodules and cavities through CT imaging. With the addition of patients from the literature, the mortality rate of patients coinfected with influenza and IPA was 41.3%, although no significant differences in mortality were observed between the coinfected and control groups. Furthermore, coinfected patients experienced longer stays in the ICU and longer total hospitals stays compared with control patients, according to the study.

The researchers also wanted to assess outcome predictors. Therefore, they compared survivors of influenza and IPA coinfection with nonsurvivors and found that a poor prognosis was predicted by higher Sequential Organ Failure Assessment Scores, CD4+ T cell counts lower than 200 cells/L upon ICU admission, and more extracorporeal membrane oxygenation requirements.

These results suggested that influenza may cause damage to the respiratory mucosa and disrupt ciliary clearance, which means it could be a “novel host risk factor” for invasive fungal infections, including aspergillosis.

“A lack of awareness, the interference of underlying influenza, and the limited use of serological diagnostic methods in some medical institutions impeded the prompt diagnosis of IPA coinfection, delayed therapies and thus led to a high mortality rate,” Huang and colleagues wrote. “With the high incidence and mortality rates observed, awareness should be raised regarding influenza as an important risk factor for IPA coinfection, and medical care providers should watch for IPA during the course of influenza.” – by Marley Ghizzone

Disclosures: The authors report no relevant financial disclosures.

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