Clinical mimics: an emergency medicine focused review of pneumonia mimics

The role of empiric atypical antibiotic coverage in non-severe community-acquired pneumonia

A β-lactam plus a macrolide or a respiratory fluoroquinolone alone is recommended as standard empiric antibacterial therapy for non-severe adults hospitalized with community-acquired pneumonia (CAP) per Infectious Diseases Society of America guidelines. However, the evidence in support of adding empiric atypical antibacterial therapy, and specifically the addition of a macrolide, is conflicting and should be balanced with additional factors: the necessity of covering atypical organisms, benefits of macrolide-associated immunomodulation, harms associated with antibiotic use, and selection for antibiotic-resistant organisms. In this review, we examine the role of atypical coverage in standard treatment regimens for patients admitted with non-severe CAP and specifically focus on the addition of macrolides to β-lactams. We conclude that a subset of patients should not be given atypical coverage as part of their regimen.

Can clinicians identify community-acquired pneumonia on ultralow-dose CT? A diagnostic accuracy study

BACKGROUND

Without increasing radiation exposure, ultralow-dose computed tomography (CT) of the chest provides improved diagnostic accuracy of radiological pneumonia diagnosis compared to a chest radiograph. Yet, radiologist resources to rapidly report the chest CTs are limited. This study aimed to assess the diagnostic accuracy of emergency clinicians' assessments of chest ultralow-dose CTs for community-acquired pneumonia using a radiologist's assessments as reference standard.

METHODS

This was a cross-sectional diagnostic accuracy study. Ten emergency department clinicians (five junior clinicians, five consultants) assessed chest ultralow-dose CTs from acutely hospitalised patients suspected of having community-acquired pneumonia. Before assessments, the clinicians attended a focused training course on assessing ultralow-dose CTs for pneumonia. The reference standard was the assessment by an experienced emergency department radiologist. Primary outcome was the presence or absence of pulmonary opacities consistent with community-acquired pneumonia. Sensitivity, specificity, and predictive values were calculated using generalised estimating equations.

RESULTS

All clinicians assessed 128 ultralow-dose CTs. The prevalence of findings consistent with community-acquired pneumonia was 56%. Seventy-eight percent of the clinicians' CT assessments matched the reference assessment. Diagnostic accuracy estimates were: sensitivity = 83% (95%CI: 77-88), specificity = 70% (95%CI: 59-81), positive predictive value = 80% (95%CI: 74-84), negative predictive value = 78% (95%CI: 73-82).

CONCLUSION

This study found that clinicians could assess chest ultralow-dose CTs for community-acquired pneumonia with high diagnostic accuracy. A higher level of clinical experience was not associated with better diagnostic accuracy.