ABSTRACT
A case-case-control study was conducted to identify independent risk factors for recovery of Escherichia coli strains producing CTX-M-type extended-spectrum ß-lactamases (CTX-M E. coli) within a large Southeastern Michigan medical center. Unique cases with isolation of ESBL-producing E. coli from February 2010 through July 2011 were analyzed by PCR for blaCTX-M, blaTEM, and blaSHV genes. Patients with CTX-M E. coli were compared to patients with E. coli strains not producing CTX-M-type ESBLs (non-CTX-M E. coli) and uninfected controls. Of 575 patients with ESBL-producing E. coli, 491 (85.4%) isolates contained a CTX-M ESBL gene. A total of 319 (84.6%) patients with CTX-M E. coli (282 [74.8%] CTX-M-15 type) were compared to 58 (15.4%) non-CTX-M E. coli patients and to uninfected controls. Independent risk factors for CTX-M E. coli isolation compared to non-CTX-M E. coli included male gender, impaired consciousness, H2 blocker use, immunosuppression, and exposure to penicillins and/or trimethoprim-sulfamethoxazole. Compared to uninfected controls, independent risk factors for isolation of CTX-M E. coli included presence of a urinary catheter, previous urinary tract infection, exposure to oxyimino-cephalosporins, dependent functional status, non-home residence, and multiple comorbid conditions. Within 48 h of admission, community-acquired CTX-M E. coli (n = 51 [16%]) and non-CTX-M E coli (n = 11 [19%]) strains were isolated from patients with no recent health care contacts. CTX-M E. coli strains were more resistant to multiple antibiotics than non-CTX-M E. coli strains. CTX-M-encoding genes, especially bla(CTX-M-15) type, represented the most common ESBL determinants from ESBL-producing E. coli, the majority of which were present upon admission. Septic patients with risk factors for isolation of CTX-M E. coli should be empirically treated with appropriate agents. Regional infection control efforts and judicious antibiotic use are needed to control the spread of these organisms.
Subject(s)
Escherichia coli Infections/epidemiology , Escherichia coli Proteins/metabolism , Escherichia coli/isolation & purification , beta-Lactamases/metabolism , Aged , Aged, 80 and over , Ambulatory Care , Case-Control Studies , Ciprofloxacin/pharmacology , Community-Acquired Infections/microbiology , Drug Resistance, Multiple, Bacterial , Escherichia coli/drug effects , Escherichia coli/enzymology , Escherichia coli/genetics , Escherichia coli Infections/drug therapy , Escherichia coli Proteins/genetics , Female , Genes, Bacterial , Humans , Male , Microbial Sensitivity Tests , Middle Aged , Retrospective Studies , Risk Factors , Trimethoprim, Sulfamethoxazole Drug Combination/pharmacology , United States/epidemiology , Urinary Catheters/microbiology , Urinary Tract Infections/microbiology , beta-Lactamases/geneticsABSTRACT
Linezolid is an important agent for the treatment of infections because of vancomycin-resistant Enterococcus (VRE). This study identified independent predictors for isolation of linezolid-resistant VRE (LZD-R-VRE) and analyzed outcomes associated with linezolid resistance. Immunosuppression, prior surgery, and previous exposure to ß-lactam antibiotics were independent predictors for isolation of LZD-R-VRE but not for LZD-susceptible-VRE. Prior exposure to linezolid was not a predictor for isolation of LZD-R-VRE.
