Background: Solid organ transplant recipients (SOTR) are at an increased risk of colonization and infections with multi-drug resistant organisms (MDROs). Antimicrobial stewardship strategies emphasize that empiric antimicrobial therapy should be patient specific, guided by local data and the presumptive site of infection.
Methods: Retrospective review of the microbiology surveillance system (Vigilanzñ) comparing antimicrobial susceptibilities patterns of bacterial isolates between blood and urine cultures in SOTR at a 1550-beds hospital in Miami, Florida (01/01/2013 to 12/30/2014). Only the first positive isolate per patient was included. Antibiograms (ATB) were categorized by source (blood and urine). Proportions of bacterial susceptibilities to specific antibiotics were compared between cultures by source and with the hospital-wide pooled ATB using Chi-square or Fisher's exact test accordingly.
Results: 1005 unique patient isolates in SOTR were identified, 606 (60.3%) from urine, and 399 (39.7%) from blood. The most frequently isolated GNR in urine was Escherichia coli 183/606(30.2%), and Klebsiella pneumoniae (48/399 (12%) in blood. Among E. coli isolates, ceftriaxone susceptibilities were urine 52%, blood 46% and hospital-wide ATB 85% (p<0.0001) (Fig. 1). E. coli susceptibilities to fluoroquinolones were <60% in urine, blood, and hospital-wide ATB. Regarding K. pneumonia, both urine and blood isolates had significantly different susceptibilities to all antibiotics compared to the hospital-wide ATB (Fig. 2). Differences were also seen when comparing susceptibilities to cefepime in urine vs blood (79% vs 59%; p=0.02), and meropenem (urine 85% vs. blood 65% [p=0.002]). P. aeruginosa susceptibilities to meropenem were urine 60%, blood 42% vs. hospital-wide ATB 76% (p=0.03) (Fig. 3).
Conclusion: We found significant differences in susceptibilities between isolates from blood and urine cultures in our SOTR compared to the hospital-wide antibiogram. Use of SOTR specific antibiograms with further analysis by source, could guide more appropriate empiric antimicrobial therapy in this group of patients at high risk for MDR infections.
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