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Canadian Journal of Infectious Diseases
Volume 6, Issue 1, Pages 44-48
Case Report

Transient in Vivo Selection of a Constitutively Cephalosporin Resistant Enterobacter Cloacae Causing Ventriculitis

Ari Joffe, Amin Kabani, Karam Ramotar, Wally Krulicki, Gisele Cadrain, and Taj Jadavji

Alberta Children’s Hospital and The University of Calgary, Calgary, Alberta, Canada

Received 14 February 1994; Accepted 14 June 1994

Copyright © 1995 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


A case of neonatal ventriculitis complicating a ventriculoperitoneal shunt and caused by one strain of Enterobacter cloacae (as shown on pulsed field gel electrophoresis) is presented. Daily ventricular fluid cultures from day 1 to 9 revealed inducible cephalosporin resistance in all isolates except on days 3, 4 and 5 of therapy when isolates were constitutively resistant. This emergence of resistance due to constitutive Bush class 1 beta-lactamase production is an excellent example of the rapid emergence of a predominant strain of bacteria depending on antibiotic selection pressures in vivo. The transient nature of the predominant resistant phenotype may have been due to missing a dose of cefotaxime on day 5 or in vivo factors allowing persistence of sensitive organisms in antibiotic protected sites. Caution is advised in the use of cephalosporins alone for serious Enterobacter species infections. Repeat culture and sensitivity should be done in severe infections that are slow to respond to cephalosporin therapy.