Comparison of Hospitalwide and Custom Antibiograms for Clinical Isolates of Pseudomonas aeruginosa

Abstract

Background: Hospital antibiograms, which are commonly used to determine empiric antibiotic therapy and as a tool in stewardship in a given institution, are open to bias when combining susceptibility results from various sources, hospital locations, and patient groups. Methods: We assessed such differences, using Pseudomonas aeruginosa as a test case, with susceptibility data from 2008 through 2010 in our institution. Each year's data were analyzed separately. A variety of specific or subcategorical antibiograms were compared with each other as well as with versions including all tested isolates and those with results from inpatients and outpatients only. Statistical significance was determined at the .01 level using either chi-square or Fisher exact test, and clinical significance was defined as $10 percentage points. Results: A variety of clinically significant differences were found that illustrated important differences within the intensive care unit environment and based on population, specifically adult versus pediatric. Concordance between statistically significant and clinically significant differences was poor. Conclusion These results corroborate and extend previous similar observations and point to the potential importance of subanalyses in preparing the annual hospital antibiogram.

Analysis and Presentation of Cumulative Antimicrobial Susceptibility Test Data – The Influence of Different Parameters in a Routine Clinical Microbiology Laboratory

“…Several previous studies compared unit-specific antibiograms for ICU- and non-ICU-patients. Focusing on merely the MRSA percentage [ 7 , 9 , 14 ] or Pseudomonas aeruginosa resistance rates [ 25 , 29 ], the authors typically observed higher values in the ICUs, namely 2 to 30 percentage points higher depending on the study setting. However, studies showing ICU / non-ICU comparisons for a broader spectrum of species/antibiotic combinations described rather inconsistent differences just as we did [ 10 , 23 , 30 – 32 ].…”

“…Further unit-specific analyses have been provided with respect to pediatric patients and elderly people. For pediatric units, researchers observed mainly lower resistance rates for a number of species/antibiotic combinations in comparison to the hospital-wide antibiogram [ 23 , 24 , 27 , 29 , 33 ]. Results were most pronounced for fluoroquinolones with 10 to 25 percentage points lower resistance rates in patients ≤18 years.…”

“…In previous studies, resistance rates were often similar for different specimen types or showed merely unpredictable deviations [ 7 , 10 , 23 , 29 ]. However, one study found mainly higher resistance rates of blood culture isolates for several examined species/antibiotic combinations [ 32 ] which is in contrast to our data, whereas another study also found lower resistance rates in Staphylococcus aureus isolates from normally sterile body sites [ 13 ].…”

Variation in Empiric Coverage Versus Detection of Methicillin-ResistantStaphylococcus aureusandPseudomonas aeruginosain Hospitalizations for Community-Onset Pneumonia Across 128 US Veterans Affairs Medical Centers

“…, 33 However, none of the currently proposed risk prediction models uses local prevalence, and most clinicians lack this information about their settings. Standardized, 34 setting-specific 35 and population-specific 36 antibiograms may improve use. Providing clinicians with patient-specific and setting-specific microbiology information at the point of care is well within the capabilities of an electronic health record and is an important step to helping clinicians better align their antimicrobial coverage decisions with actual risk.…”

Development of a Statewide Antibiogram to Assess Regional Trends in Antibiotic-Resistant ESKAPE Organisms

“…Although there is no evidence-based standard, one analysis picked an arbitrary !10% susceptibility difference for clinical significance when comparing antibiograms between different hospital units. 21 In contrast, some clinicians may feel clinical significance is exhibited with more modest susceptibility differences, and this threshold could vary between different organism/drug combinations and disease states. Furthermore, since our antibiogram analysis incorporated isolates from all culture sites and hospital units, our cumulative antibiogram, by design, may have been less likely to portray a multitude of clinically significant differences.…”