Bacterial Pneumonia-Complicating Influenza: Risks, Morbidity, and Mortality

“In our department we have largely migrated away from using the healthcare associated pneumonia (HCAP) criteria when deciding which [patients with] pneumonia to treat with broad-spectrum antibiotics with coverage against multidrug-resistant bacteria,” said Wesley H. Self, MD, MPH, associate professor and vice chair for research, Department of Emergency Medicine, Vanderbilt University Medical Center, in Nashville, Tennessee, in an interview with Pulmonology Advisor. “This change was based on many studies, including this one, that have shown the risk of multidrug-resistant bacteria like MRSA is quite low for many patients who meet the HCAP criteria. An ideal approach for selecting antibiotics for pneumonia is still somewhat elusive, but I think we have learned that adherence to HCAP criteria tends to lead to overprescribing of anti-MRSA and antipseudomonal antibiotics.”

Characterizing Coinfection in Influenza Pandemics

After the 2009 influenza pandemic, the A/H1N1 strain was most frequently implicated in the most severe influenza infections, yet A/H1N1 did not contribute disproportionately to the number of patients with coinfections, as illustrated in a retrospective study in Beijing, China.5 The 209 patients (median age, 59 years; 65.1% men) with influenza-associated CAP were admitted to a single hospital from 2010 to 2018.5

S aureus was the most common strain of the nearly 1 in 5 patients who had bacterial and viral coinfections.5 Patients with coinfection vs those without coinfection had higher Acute Physiology and Chronic Health Evaluation and Sequential Organ Failure Assessment scores, as well as higher rates of sepsis shock, mechanical ventilation, and ICU admission.5 Independent risk factors for hospital mortality were coinfection (adjusted hazard ratio [aHR], 2.619; 95% CI, 1.252-5.480; P =.011) and S aureus strain (aHR, 6.267; 95% CI, 2.679-14.662; P <.001).5

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Coinfection in Pediatric Populations

El Baroudy and colleagues studied 132 children (mean age, 2.95 years; 56.8% girls) at a hospital in Cairo, Egypt, in a 1-year prospective study to determine the prevalence of coinfection in children presenting with acute respiratory infections.6 Viruses were implicated in 20.8% of all infections, most of which were rhinoviruses and respiratory syncytial virus. Mycoplasma was the most prominent of the atypical bacterial etiologies. Coinfection occurred in 10.6% of the cases.6

“Recently with the spread of new emerging viruses, substantial changes in disease burden have occurred and associated mortality was noticeably increased,” said study coauthor Amira S. El Refay, PhD, Department of Child Health, National Research Centre in Cairo, Egypt, in an interview with Pulmonology Advisor. “These are largely due to pneumonia resulting from expansion of the viral infection to the lower respiratory tract. Management protocols and empiric treatment algorithms for pneumonia in developing countries were [established] before these recent changes in the epidemiology of the disease, as viral pneumonia is usually diagnosed by exclusion because of lack of diagnostic facilities. This in turn leads to underestimated incidence of the disease.”

Summary and Clinical Applicability

Viral and bacterial coinfection are often implicated in many cases of CAP and HAP. Even with the advent of molecular testing, clinicians need to time the tests carefully to identify the correct pathogens.

Limitations and Disclosures




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This article originally appeared on Pulmonology Advisor