Background: There is a growing appreciation of the increasing prevalence of CREs, but limited data exists on the prevalence of invasive infections due to CRE among adult, hospitalized patients in the various geographic regions of the United States (US). Cognizant of this data gap, the study objective was to quantify the prevalence of carbapenem resistance among adult, hospitalized patients with invasive infections due to Enterobacteriaceae using data from a large US hospital database.
Methods: Retrospective study using data from the Premier inpatient research database among institutions that contribute microbiology data. Study period: 6/1/2010-12/31/2013. Inclusion criteria: (1) age ≥ 18 yrs; (2) primary or secondary ICD-9 diagnosis at discharge for a complicated urinary tract infection, complicated intra-abdominal infection, hospital-associated pneumonia, OR bloodstream infection; (3) positive culture for an Enterobacteriaceae spp. drawn from a site consistent with the infection type, and (4) receipt of antibiotic treatment on day of Enterobacteriaceae culture collection OR ≤ 3 days after index Enterobacteriaceae culture. Carbapenem resistance was defined as non-susceptibility to meropenem, imipenem, doripenem, or ertapenem. Prevalence of CRE was examined across US geographic regions and stratified by pathogen (Klebsiella spp., Enterobacter spp., E. coli, and other [Citrobacter spp. and Serratia spp.]).
Results: During the study period, 30,875 patients met the study criteria. The overall prevalence of CRE was 3%. The prevalence of CRE by US region and pathogen are presented below.
| Region |
All CRE |
Klebsiella spp. |
Enterobacter spp. |
E. coli |
Other |
|||||
|
Pts |
%-R |
Pts |
%-R |
Pts |
%-R |
Pts |
%-R |
Pts |
%-R |
|
| EAST NORTH CENTRAL |
4,947 |
4.1% |
1,555 |
10.7% |
565 |
3.7% |
2,848 |
0.3% |
522 |
1.9 |
| EAST SOUTH CENTRAL |
2,009 |
2.2% |
607 |
4.3% |
254 |
3.5% |
1,149 |
0.8% |
207 |
1.9 |
| MIDDLE ATLANTIC |
3,480 |
7.4% |
1,176 |
15.3% |
424 |
15.3% |
1,967 |
1.0% |
371 |
2.7 |
| MOUNTAIN |
427 |
6.1% |
122 |
9.0% |
39 |
12.8% |
250 |
1.6% |
36 |
19.4 |
| NEW ENGLAND |
1,416 |
1.8% |
367 |
1.4% |
156 |
7.1% |
874 |
0.8% |
126 |
1.6 |
| PACIFIC |
5,346 |
2.0% |
1,291 |
3.4% |
429 |
6.5% |
3,701 |
0.5% |
404 |
4.7 |
| SOUTH ATLANTIC |
7,006 |
2.8% |
2,229 |
4.2% |
784 |
7.9% |
4,020 |
0.6% |
630 |
3.8 |
| WEST NORTH CENTRAL |
2,280 |
1.6% |
596 |
4.5% |
250 |
2.8% |
1,415 |
0.1% |
183 |
0.0 |
| WEST SOUTH CENTRAL |
3,964 |
1.3% |
949 |
2.3% |
339 |
1.2% |
2,741 |
0.5% |
278 |
5.4 |
Conclusions: The prevalence of CRE ranged between 1.3% and 7.4% by geographic region. In several regions, the prevalence of carbapenem resistance among patients with invasive infections due to Klebsiella spp. and Enterobacter spp. exceeded 10%. Given the rising incidence of CRE there is a need to have mechanisms for ongoing monitoring at a regional and hospital level. Further, it is important to initiate appropriate therapy early-on in the treatment pathway and this highlights need for developing decision support system tools/algorithms for identification of patients who are at high risk for CRE. This information will be critically important for clinicians when selecting empirical treatment for patients as culture results are typically not available within the first 48-72 hours of infection onset.