Clinical outcome of extended-spectrum beta-lactamase-producing Escherichia coli bacteremia in an area with high endemicity.

OBJECTIVES: This study assessed the impact of discordant empirical antibiotic therapy on the outcome of bacteremia caused by extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli. METHODS: The clinical features and outcomes of a cohort of patients hospitalized with ESBL E. coli bacteremia between 2007 and 2008 were retrospectively reviewed. The effect of different antimicrobial regimens on patient outcomes was analyzed. RESULTS: ESBL E. coli accounted for 24.2% (207/857) of E. coli bacteremia cases. The urinary tract (43.6%) was the most common source of infection, followed by the hepatobiliary tract (23.0%). Discordant empirical antibiotic therapy was given to 52.0% patients. Admission to the intensive care unit was associated with the use of a carbapenem as empirical antibiotic therapy (p<0.001). Univariate analysis revealed no significant differences in 30-day mortality rates between patients receiving concordant and discordant empirical antibiotic therapy (23.5% vs. 19.8%, p=0.526), carbapenem and non-carbapenem empirical antibiotic therapy (29.8% vs. 19.1%, p=0.118), beta-lactam/beta-lactam inhibitor combinations (BLBLIs) and non-BLBLIs empirical antibiotic therapy (20.3% vs. 22.3%, p=0.734), cephalosporin and non-cephalosporin empirical antibiotic therapy (19.7% vs. 22.6%, p=0.639), and fluoroquinolone and non-fluoroquinolone empirical antibiotic therapy (8.3% vs. 22.4%, p=0.251). The findings were confirmed by multivariate analysis. CONCLUSIONS: Despite a high proportion of discordant empirical antibiotic therapy, ESBL production had little effect on 30-day mortality. Whether the observation can be applied to different ESBL types is unknown and warrants further study.

Epidemiology of Klebsiella oxytoca-associated diarrhea detected by Simmons citrate agar supplemented with inositol, tryptophan, and bile salts.

We studied the clinical and epidemiological characteristics of Klebsiella oxytoca-associated diarrhea in hospitalized patients in Hong Kong. Between 1 November 2009 and 30 April 2011, all inositol-fermenting colonies found on Simmons citrate agar supplemented with inositol, tryptophan, and bile salts (SCITB agar) used for the culturing of diarrheal stool samples were screened by a spot indole test for K. oxytoca. The overall sensitivity of SCITB agar plus the spot indole test (93.3%) for the detection of K. oxytoca in stool samples was superior to that of MacConkey agar (63.3%), while the specificities were 100% and 60.4%, respectively. The former achieved a 23-fold reduction in the workload and cost of subsequent standard biochemical identifications. Cytotoxin production and the clonality of K. oxytoca were determined by a cell culture cytotoxicity neutralization assay using HEp-2 cells and pulsed-field gel electrophoresis (PFGE), respectively. Of 5,581 stool samples from 3,537 patients, K. oxytoca was cultured from 117/5,581 (2.1%) stool samples from 104/3,537 (2.9%) patients. Seventy-six of 104 (73.1%) patients with K. oxytoca had no copathogens in their diarrheal stool samples. Twenty-four (31.6%) of 76 patients carried cytotoxin-producing strains, which were significantly associated with antibiotic therapy after hospital admission (50% versus 21.2%; P = 0.01). Health care-associated diarrhea was found in 44 (42%) of 104 patients with K. oxytoca, but there was no epidemiological linkage suggestive of a nosocomial outbreak, and PFGE showed a diverse pattern. None of the patients with cytotoxin-producing K. oxytoca developed antibiotic-associated hemorrhagic colitis, suggesting that K. oxytoca can cause a mild disease manifesting as uncomplicated antibiotic-associated diarrhea with winter seasonality.