Clinical evaluations of the Wellcolex Colour Shigella and Salmonella tests.

The Wellcolex Colour Salmonella and Shigella tests are rapid latex agglutination procedures for grouping Salmonella and Shigella using an antibody attached to multicolored latex particles. The tests correctly grouped 46 (100%) of 46 Salmonella clinical isolates in groups A through E and G, 42 (100%) of 42 Shigella clinical isolates, and seven (88%) of eight Shigella stock cultures. The stock culture missed had been passed through many transfers and may have lost some of its antigenicity. The Wellcolex Colour Salmonella test was also found useful in detecting and grouping Salmonella spp. directly from blood culture bottles.

Atypical Streptococcus pyogenes from an ear discharge.

An atypical variant of Streptococcus pyogenes was isolated from a discharge from a child's ear. Although this variant streptococcus grew aerobically on chocolate agar, the isolate would not grow on blood agar, the medium used to screen for S. pyogenes, unless it was incubated anaerobically or incubated in air with cocarboxylase.

Vaginitis caused by nutritionally variant Streptococcus pyogenes.

A nutritionally variant Streptococcus pyogenes was isolated from a vaginal specimen. The organism was isolated in essentially pure culture with a few colonies of normal vaginal flora. The bacterium was identified as Streptococcus pyogenes with the use of rapid test kits and the presence of group A antigen.

Multicenter clinical evaluation of a continuous monitoring blood culture system using fluorescent-sensor technology (BACTEC 9240).

The BACTEC 9240 (Becton Dickinson Diagnostic Instrument Systems, Sparks, Md.) is a new continuous-monitoring blood culture system that uses internal, fluorescent-CO2 sensors. In a multicenter clinical trial, organism yield and times to detection with the prototype BACTEC 9240 system were compared with those of the BACTEC NR 660 system. Equal volumes of blood were inoculated into the bottles included in the study blood culture sets (aerobic and anaerobic 9240 and NR6A and NR7A bottles). A total of 9,391 aerobic and 8,951 anaerobic bottle pairs were inoculated with 9,801 blood specimens. A total of 587 clinically significant positive blood cultures and 415 cases of sepsis were studied. The standard 9240 aerobic bottle detected significantly more Staphylococcus aureus (P < 0.05), coagulase-negative staphylococci (P < 0.01), and total microorganisms (P < 0.001) than the NR6A bottle. The standard 9240 anaerobic bottle detected significantly more coagulase-negative staphylococci (P < 0.001), members of the family Enterobacteriaceae (P < 0.01), and total microorganisms (P < 0.001) than the NR7A bottle. A total of 420 positive cultures were detected in both systems; for 284, the time to detection was equivalent with both systems (within 12 h); for 123, the 9240 system was faster; and for 13, the NR 660 system was faster (P < 0.001). The average times to detection for the 9240 and the NR 660 systems were 20.2 and 27.5 h, respectively. Ninety-nine cultures were positive only in the 9240 system, and 68 cultures were positive only in the NR 660 system (P < 0.02). The 9240 system also detected significantly more episodes of bacteremia (P < 0.001). The false-positive rates for the 9240 and NR 660 systems were 2.2 and 2.3%, respectively. The false-negative rates for the two systems after 5 days of incubation did not differ significantly. The contamination rates for the 9240 and NR 660 systems were 1.9 and 1.5%, respectively (P < 0.05). In conclusion, the prototype 9240 system detected more clinically significant positive blood cultures and did so sooner than the NR 660 system, with the additional advantages of full automation, continuous monitoring, and noninvasive sampling.