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

Vincent C.C. Cheng, Wing Cheong Yam, Lee Lee Tsang, Miranda C.Y. Yau, Kit Hang Siu, Sally C.Y. Wong, Jasper F.W. Chan, Kelvin K.W. To, Herman Tse, Ivan F.N. Hung, Josepha W.M. Tai, Pak Leung Ho, Kwok Yung Yuen

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Abstract

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.
Original languageEnglish
Pages (from-to)1571-1579
Number of pages9
JournalJournal of Clinical Microbiology
Volume50
Issue number5
DOIs
Publication statusPublished - 1 May 2012
Externally publishedYes

ASJC Scopus subject areas

  • Microbiology (medical)

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