Clinical Characteristics in Patients With Hospital-acquired Pneumonia Caused by Extensively Drug-resistant Acinetobacter Baumannii, a Multicenter Retrospective Study

Background Extremely drug-resistant （XDR） Acinetobacter baumannii （A. baumannii）has been of a great concern. The relationship between XDR and patient outcomes remains unclear. We investigated the clinical features, risk factors, and outcomes of Hospital-acquired pneumonia (HAP)caused by XDR A. baumannii. Methods A multicenter retrospective case-control study was performed to determine factors associated with XDR A. baumannii pneumonia from 5 teaching hospitals in Guangzhou, China. Results 76 patients were enrolled in the study. XDR A. baumannii pneumonia patients were tend to be smoker (11.9% vs 3.9%, P = 0.130) and older (76.5±11.2 vs 70.3±16.4, P = 0.007) and had more comorbid diseases including chronic obstructive pulmonary disease (COPD) (48.7% vs 21.1%, P = 0.001) and renal failure (21.1% vs 3.9%, P = 0.002) and had higher APACHE II score (65.8% vs 47.4%, P = 0.033). Invasive procedures including insertion of urinary catheter, nasogastric tube, central venous/arterial catheter, bronchoscopy and mechanical ventilation along with using β-lactam/β-lactamase inhibitor and carbapenem were also risk factors for XDR A. baumannii pneumonia. Multivariate analysis showed the APACHE II score >=20 (OR, 2.1; 95% CI: 1.1–4.1, P = 0.023), COPD (OR, 9.6; 95% CI: 2.0–45.5, P = 0.004), central venous/arterial catheter placement (OR,11.5; 95% CI: 1.1-117.8, P = 0.040), low albumin levels (OR, 1.2; 95% CI: 1.1-1.4, P = 0.001) and using β-lactam/β-lactamase inhibitor (OR,15.9; 95% CI: 2.7-94.2, P = 0.002) were independent risk factors for XDR A. baumannii pneumonia. Compared with the non-XDR A. baumannii patients, the XDR A. baumannii pneumonia increased length of mechanical ventilation (11.1±12.3 vs 5.1±5.6, P = 0.000), hospital stay (42.2±24.3 vs 34.8±18.0, P = 0.036) and ICU (Intensive Care Unit) stay (27.5±19.0 vs 20.0±20.5, P = 0.020), but it did not increase in-hospital mortality (47.4% vs 32.9%, P = 0.137). Conclusions XDR A. baumannii pneumonia was strongly related to systemic illnesses, invasive procedure, low albumin levels and the APACHE II score and increasing the length of mechanical ventilation and hospital stay. But it did not increase in-hospital mortality.