Abstract
BackgroundAcinetobacter baumannii hospital-acquired pneumonia (HAP) is associated with a high mortality worldwide. Non-ventilated patients with HAP (NVHAP) caused by nosocomial pathogens are reported to have a more favorable outcome than those with ventilator-associated pneumonia (VAP). The current study was designed to determine whether bacteremic patients with A. baumannii NVHAP also have a lower mortality than those receiving assisted ventilation.MethodsThis retrospective 10-year study was conducted at a 2900-bed teaching hospital located in Northern Taiwan. The population consisted of 144 patients with A. baumannii bacteremia and HAP. Of these 96 had VAP and 48 had NVHAP. Charts were reviewed for demographic characteristics, comorbidities, clinical manifestations, antimicrobial susceptibility, and 14-day mortality. Clonal relationships were determined by molecular typing.ResultsThere were no significant differences between the two groups in comorbidities (Charlson scores). Patients with NVHAP were more likely to have developed bacteremia earlier, outside the ICU and undergone fewer invasive procedures. They had significantly lower APACHE II scores, fewer bilateral pneumonias and lower rates of antimicrobial resistance. No specific clones were identified in either group. The unadjusted (crude) 14-day mortality rates were not significantly different between the groups (NVHAP 43.8% vs. VAP 31.3%, p = 0.196). The adjusted 14-day mortality risk was significantly lower in ventilator-assisted patients (odds ratio = 0.201; 95% confidence interval = 0.075-0.538; p = 0.001).ConclusionsPatients with bacteremic NVHAP and VAP caused by A. baumannii had similar crude mortality rates, but on logistic regression analysis those receiving ventilator assistance had a significantly lower mortality. This may have been due to better airway protection, more intensive monitoring with earlier diagnosis and treatment in patients with VAP, greater innate susceptibility to infection in those with NVHAP and differences in the virulence of A. baumannii.
Highlights
Acinetobacter baumannii hospital-acquired pneumonia (HAP) is associated with a high mortality worldwide
The inclusion criteria for A. baumannii pneumonia [15] consisted of: a) at least one positive respiratory sample for A. baumannii obtained within 48 hours before or after the first positive blood culture; b) a clinical course compatible with pneumonia, including symptoms of acute respiratory infection and acute infiltrates on a chest radiograph; and c) the positive blood culture could not be attributed to another source of infection
In addition to the clinical features and radiographic findings that were compatible with diagnosis of pneumonia, 93 ventilator-associated pneumonia (VAP) patients had positive cultures from endotracheal aspirates, three from Broncho-alveolar lavage (BAL), and all Non-ventilated patients with HAP (NVHAP) patients from sputum specimens
Summary
Acinetobacter baumannii hospital-acquired pneumonia (HAP) is associated with a high mortality worldwide. Non-ventilated patients with HAP (NVHAP) caused by nosocomial pathogens are reported to have a more favorable outcome than those with ventilator-associated pneumonia (VAP). It has been previously reported that nonventilated patients with HAP (NVHAP) caused by nosocomial pathogens have a better outcome than those with ventilator-associated pneumonia (VAP) [12,13,14]. It is not known whether this applies to A. baumannii as well. The current retrospective study was designed to determine whether patients with A. baumannii bacteremic NVHAP have a better outcome than those with bacteremic VAP
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