Gram-negative resistance and need for ICU among urinary tract infections in the United States

Introduction

Urinary tract infection (UTI) can lead to both hospitalization and severe sepsis. We theorized that UTI due to Gram-negative (GN) multidrug-resistant P. aeruginosa (MDR-PA), extended-spectrum ß-lactamase (ESBL), E. coli (EC) and Klebsiella sp. (KP), and carbapenemase-producing Enterobacteriaceae (CPE) would be frequently isolated in the ICU.

Methods

We analyzed a large US-based microbiology database, Eurofins TSN, between the years 2000 and 2009. We determined the proportion of isolates caused by MDR-PA, ESBL-EC, ESBL-KP, and CPE relative to their susceptible counterparts. We defined MDR-PA as any isolate resistant to ≥3 drug classes. ESBL organisms were defined as E. 3coli and K. pneumoniae resistant to a third-generation cephalosporin. Enterobacteriaceae were considered CPE if resistant to both a third-generation cephalosporin and a carbapenem. We further examined the evolution of the frequency of resistance among GN UTIs over time.

Results

We identified 115,201 PA (13.7% MDR-PA), 359,090 EC (5.6% ESBL), 97,419 KP (12.9% ESBL), and 176,110 Enterobacteriaceae (0.6% CPE) UTI specimens. The prevalence of resistance rose for each organism of interest from 2000 through 2009: MDR-PA, 11.6 to 12.3%; ESBL-EC, 3.3 to 8.0%; ESBL-KP, 9.1 to 18.6%; CPE 0 to 2.3%. For each organism the proportion of resistant pathogens was consistently higher among ICU specimens than among specimens from other hospital locations, reaching nearly 20% for MDR-PA (Figure 1).

Figure 1

(abstract P74)

Conclusion

The microbiology of GN UTI hospitalizations has shifted over the last decade and greater antimicrobial resistance is evident. The prevalence of MDR-PA, ESBL-EC, ESBL-KP, and CPE is higher in the ICU than in other hospital locations.