Evaluation of an improved Streptex kit for the grouping of beta-haemolytic streptococci by agglutination.

A modified Streptex kit in which the extraction procedure had been simplified was used to group 200 streptococcal strains. Positive reactions could be obtained with live colonies and over 90% of isolates were correctly grouped from primary isolation plates. Some minor cross-reactions were seen with Streptex, but these were not strong enough to cause any confusion and no isolates were incorrectly grouped. The extraction enzyme in the Streptex kit was relatively poor at extracting the group-specific teichoic acid of group D strains but worked well with groups A, B, C, F and G.

Early detection of bacterial growth in blood culture by impedance monitoring with a Bactometer model 32.

A Bactometer model 32 was evaluated for use in early detection of bacterial growth. Experiments with simulated cultures showed that 2 ml of broth introduced into the Bactometer module wells could detect 10(2) and 10(6) CFU/ml in 6 h and 2 h respectively. Both Brain Heart Infusion (BHI) and Fastidious Anaerobic broths supported good growth. Detection of nine of 10 organisms inoculated at approximately 10(6) CFU/ml in BHI were detected within 8.5 h. A culture of Bacteroides fragilis failed to grow under these conditions. Of 189 blood cultures, tested by incubation of 2 ml of BHI, 18 were positive by both conventional and Bactometer methods. False-positive or false-negative specimens were not observed using the Bactometer. Use of the Bactometer enables growth detection at least 12 h earlier than culture methods.

Evaluation of the Lumac kit for the detection of bacteriuria by bioluminescence.

Four hundred and twenty-two urine samples were screened for significant bacteriuria using bioluminescence and microscopy of uncentrifuged urine. A smaller number of false-negatives were seen with bioluminescence (10%) than with microscopy (40%) while both techniques gave a similar number of false-positives (18%). The kit required a large amount of manual preparation, largely pipetting. With this and the short shelf-life of the reconstituted reagents, it is not suitable for small numbers of urines. At 45p per urine, the cost of bioluminescence is too high.

Improved diagnosis of gonorrhea in women.

Single endocervical cultures are estimated to be 85-95% reliable in the diagnosis of gonorrhea; a properly obtained rectal culture increases this yield by 5%. In this prospective trial, the increased diagnostic yields from two first-day endocervical cultures and second-day endocervical and rectal cultures were examined. The value of cervical gram smears was also reviewed. During a six-month period, 748 women were evaluated on day 1, with 195 returning for second-day cultures. The mean increased diagnostic yields were 2.2% for the second first-day endocervical culture, 2.9% for second-day cultures, and 4.0% for rectal cultures.