O serotyping scheme for Enterobacter cloacae

Abstract

A serotyping scheme for E. cloacae based on heat-stable somatic antigens is described. Antisera (28) were prepared in rabbits; agglutinin titers were high (> 640). Some cross-reactions were observed; 11 sera required absorption before routine use. Of 300 clinical isolates from 66 hospitals, 77.6% were typable, 11.4% were not agglutinated by any of the sera and 11.0% were autoagglutinable in saline. The 8 most frequent serotypes were O3 (21.3%), O8 (13.3%), O1 (7.6%), O13 (5.0%), O9 (4.7%), O10 (3.0%), O16 (3.0%) and O25 (3.0%). [This scheme may be useful in studying the hospital epidemiology of E. cloacea].