Clinical analysis on patients with bacterial community-acquired pneumonia and influenza A coinfection

Objective To explore the clinical characteristics and outcomes of patients with bacterial community-acquired pneumonia (CAP) and influenza A coinfection. Methods Data of 137 patients with bacterial CAP (bacterial infection group) and 84 patients with influenza A and bacterial CAP coinfection (coinfection group) were reviewed from four hospitals in Beijing, Qingdao and Kunming during 2014-2015. The pathogenic composition, clinical characteristics, treatments and outcomes of the two groups were compared. Results The main bacterial infections in both groups were Streptococcus pneumoniae and Haemophilus influenzae, with no statistical significances (P both>0.05) . In coinfection group, the levels of peripheral blood lymphocyte, albumin and oxygenation index were (0.7±0.5) ×109/L, (27.7±6.0) g/L and (290.9±124.6) mmHg (1 mmHg= 0.133 kPa) , which were all significantly lower than those in bacterial infection group (t=9.752, 7.690 and 5.237, P all<0.01) . CURB-65 score, PSI risk class, blood urea nitrogen, creatine kinase, wheeze, confusion, multilobar infiltrate were (1.5±0.8) scores, (3.9±1.1) scores, (8.3±5.3) mmol/L, (287.1±25.1) U/L, 77.4% 19.0% and 76.2%, were all significantly higher than those in bacterial infection group (t=-6.227, -14.704, -4.554, -2.042, χ2=39.968, 14.357, 7.264, P all<0.01) . Mechanical ventilation and vasoactive agents were more often used in coinfection group than in bacterial infection group (χ2=90.260 and 49.513, P<0.01) , while multiple organ failure/damage and septic shock were more likely to occur (P all<0.01) . ICU admission and 30-day mortality were higher in coinfection group than in bacterial infection group (χ2=86.074 and 49.404, P<0.01) . Conclusions Bacterial CAP patients co-infected with influenza A virus can exacerbate the disease and have a poorer prognosis. Key words: Influenza A virus; Bacteria; Coinfection; Community-acquired pneumonia