Impact of Appropriate Empirical Antibiotic Therapy on Clinical Outcome in Patients with Acinetobacter Baumannii Bacteremia

Background:

In this study, it was aimed to evaluate risk factors and impact of appropriate empirical antimicrobial therapy (AEAT) in patients followed up in intensive care units (ICUs) with A. baumannii on 30-day mortality and clinical outcome.

Methods:

A retrospective study was conducted at a 1100-bed tertiary care center. Patients over 18 years old with A. baumannii bacteremia in ICUs between 2009 and 2013 were enrolled into study. Patients with positive blood culture for A. baumannii and clinical findings supporting infection were defined as infected. AEAT was defined as initiation of at least one antimicrobial agent in appropriate dose and route to which the A. baumannii strain was susceptible before susceptibility results were known.

Results:

During study period 88 patients with A. baumannii bacteremia were enrolled. AEAT initiation rate was 23.1%. Overall and 30 day mortality was 63.6% and 46.5%respectively (Table 1). In AEAT group, overall and 30-day mortality were significantly lower (%43.5-%70.8 [p=0.019]; %21.7-%55.3 [p=0.05]). Survivors had lower APACHE II, SOFA, CCI scores (p<0.05). Older age, previous hospitalization in 90 days , presence of septic shock and central venous catheter(p=0.044) were significantly related with higher mortality (p<0.05). Carbapenem administration was correlated with higher survival rate in 30th day (p=0.014). Colistin, tigecycline, meropenem and amikacin resistance rates were 0%, 5.7%, 83.3%, 46% respectively.

Conclusion:

In this 5 year cohort, initiation rate of AEAT was very low. AEAT was associated with lower mortality rates.

Table 1. Various features of patients
	All patients (n=88)	AEAT (n=65)	IEAT (n=23)	P
Male gender	55 (62,5)	39 (60)	16 (69,6)	0,415
Age	59,6±17,9	59,9±18,2	58,4±17,2	0,506
Length of stay	53,4±52,6	47,6±44,7	69,9±69,1	0,416
APACHE II	23,2±8,2	23,9±8,2	21±8,2	0,315
SOFA	9,8±4,7	9,8±4,8	9,8±4,7	0,938
CCI	4,1±3,1	4,2±3,2	3,9±2,9	0,45
Overall mortality	56 (63,6)	46 (70,8)	10 (43,5)	0,019
30-day mortality	41 (46,5)	36 (55,3)	5 (21,7)	0,05
AEAT; Appropriate Empirical Antimicrobial Therapy, IEAT; Inappropriate Empirical Antimicrobial Therapy, APACHE II; Acute Physiology and Chronic Health Evaluation II score, SOFA; Sequential Organ Failure Assessment score, CCI; Charlson Comorbidity Index