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This paper describes a patient with spontaneous bacterial peritonitis caused by a group IIk-2 strain. No other organism was isolated from the peritoneal fluid cultured aerobically and anaerobically.

During this study, 2,855 stool specimens from patients at Cook County Hospital were cultured for enteric pathogens. Hektoen Enteric Agar (HE) was compared with E M B and S S Agars by replicate samplings with both direct and indirect methods. Shigella species were recovered more than twice as often on HE Agar as on S S Agar by both methods. With the direct method only, out of 98 Shigella isolated, 97 were isolated from HE Agar, 74 were recovered from E M B Agar, and 40 were found on S S Agar. In addition, HE yielded better isolation of Salmonella strains than did S S or E M B by either direct or indirect methods. The greater efficiency of HE medium is discussed with respect to colonial recognition of enteric pathogens.

A new agar plating medium for the isolation of enteric pathogens is described. This medium contains greater quantities of peptone to offset the inhibitory effects of bile salts. Additional carbohydrates and larger quantities of those previously used have also been incorporated into the medium to differentiate pathogens from some of the slow lactose fermenters. The use of an indicator system never used before in a differential plating medium opens new possibilities for improvement over traditional and newer selective media. Known strains from the various genera of Enterobacteriaceae have been tested for colonial differentiation as well as for possible inhibitory effects. The results show the medium to be highly selective for the shigellae as well as for other enteric pathogens.