An evaluation of alkaline peptone water for enrichment of Vibrio cholerae in feces.

A comparison was made to determine the sensitivity of direct inoculation of thiosulfate citrate bile salts agar (TCBS) and alkaline peptone water (APW) enrichment prior to direct inoculation of TCBS to culture Vibrio cholerae from feces of patients with gastroenteritis. V. cholerae was isolated from 611 feces specimens. Of those, 535 were isolated in TCBS and APW-TCBS, 15 in only TCBS and 61 in only APW-TCBS. V. parahemolyticus (21) and non-agglutinating vibrios (11) were also isolated but more often in direct inoculated TCBS than APW-TCBS cultures. Maximum isolation sensitivity of V. cholerae and V. parahemolyticus from feces is obtained by both direct inoculation of TCBS and enrichment in APW prior to TCBS inoculation.

Detection of Salmonella C1, D and V1 antigens, by coagglutination, in blood cultures from patients with Salmonella infections.

Protein A-containing Staphylococcus aureus was coupled to Salmonella C1, D and Vi monovalent antisera to produce C1-, D- and Vi-COAG reagents. The reagents were used to detect their homologous Salmonella antigens in blood cultures (BC). The D and Vi antigens were detected in 79 of 239 BC from patients with suspected typhoid fever and Salmonella typhi was later isolated from the same 79 BC. The C1 antigen was detected in 8 BC from which only S. oranienburg was later isolated. The COAG test was generally positive at the same time the BC became culture positive. However, because of subculture and biochemical identification requirements the COAG test could be interpreted 1-2 days before culture results were available. The COAG test can be used to presumptively identify Salmonella typhi and Salmonella group C1 in blood cultures before the culture results are available.