A simple, practical model for reducing alloimmunization in patients with sickle cell disease.

Patients with sickle cell disease (SCD) form immune alloantibodies more frequently than other transfused populations because red cells (RBCs) from white donors (with a higher incidence of certain Rh, Duffy, Kell, and Kidd blood group antigens) are transfused to black patients often lacking these antigens. We propose a model to reduce alloimmunization in patients with SCD by providing them with blood from only black random donors. Rationale is shown by examining calculations based on the phenotype E-, C-, Fy(a-), K-, and Jk(b-). There is a 7% probability that this phenotype belongs to a white donor, while there is a 93% probability that this phenotype belongs to a black donor. The probability of selecting blood from a black donor identical with the above phenotype for black recipients from an all black population and from a typical urban blood inventory population (90% white, 10% black) is 1/4 and 1/33, respectively. Therefore, an 8-fold greater chance of selecting antigen non-identical blood occurs if blood is obtained from a typical urban donor population as compared to a black population. Based on these calculations, alloimmunization can be reduced prospectively in patients with SCD by meeting their transfusion requirements with blood selected from random black blood donors.

Proline aminopeptidase activity as a rapid diagnostic test to confirm bacterial vaginosis.

Two biochemical indicators of bacterial vaginosis, proline aminopeptidase activity and gas-liquid chromatographic analysis, were compared. Five hundred women had their vaginal secretions tested for pH, presence of a positive amine test, levels of volatile and nonvolatile short-chain organic acids, and proline aminopeptidase activity. In addition, direct microscopic and Gram stain examinations were performed. Of the 500 women, 349 (70%) had some form of vaginitis. One hundred sixteen were diagnosed as having bacterial vaginosis, and 69 of these (59%) had Mobiluncus sp on either direct microscopic or Gram stain examination. Two hundred thirty-three had either mixed or other forms of vaginitis. One hundred fifty-one patients were normal. The sensitivity of the proline aminopeptidase assay was 83 and 79%, respectively, in patients having bacterial vaginosis with and without Mobiluncus morphotypes. In contrast, gas-liquid chromatography of short-chain organic acids had sensitivities of 71 and 30%, respectively. Specificity of both assays was about 95%. The greater sensitivity of the proline aminopeptidase assay, especially in patients without Mobiluncus morphotypes, proves its superiority.

BACTID: a microcomputer implementation of a PASCAL program for bacterial identification based on Bayesean probability.

A computer program (BACTID) is described which enables the identification of bacteria based on a priori data and Bayesean probability testing. The program is not limited to a specific format, has a short execution time, can be easily applied to a variety of situations, and can be run on almost any microcomputer system operating under either 8-bit CP/M or 16-bit MS-DOS or PC-DOS. Additionally, BACTID is not limited to one type of computer (hardware independent); is not limited by size of the computer's random access memory (RAM independent); can recognize various database matrices (format independent); is able to compensate for missing data; and allows for various methods of data entry. The efficacy of the program was checked against a commercially available test system and a 99.34% agreement was obtained. Also, the execution time for a 46 x 21 data matrix was as little as 3.5 seconds. These results show that microcomputer identification programs not only are viable alternatives to code-book registers, but also offer flexibility which is not found in commercial systems.

Microcomputer application of Bayesean probability testing for the identification of bacteria.

A computer program (BACTID) is described which facilitates the identification of bacteria based on a priori data and Bayesean probability testing. The program is not limited to a specific format, has a short execution time, can be easily applied to a variety of situations, and can be run on almost any microcomputer system operating under either 8-bit CP/M or 16-bit MS-DOS/PC-DOS. Additionally, BACTID (1) is not limited to one type of computer (hardware independent), (2) is not limited by size of the computer's random access (RAM independent), (3) can recognize various data bases matrices (format independent), (4) is able to compensate for missing data and (5) allows for various methods of data entry. The efficacy of the program was checked against a commercially available test system and a 99.34% agreement was obtained. Also, the execution time for a 46 x 21 element data matrix was as little as 3.5 s. These results show that microcomputer identification programs are not only viable alternatives to code book registers, but also offer flexibility which is not found in commercial systems.

Rapid glutamic acid decarboxylase test for identification of Bacteroides and Clostridium spp.

A rapid 4-h test for glutamic acid decarboxylase is described for the identification of certain anaerobic bacteria. The test substrate consisted of 1.0 g of L-glutamic acid, 0.3 ml of Triton X-155, and 0.05 g of bromcresol green sodium salt in 1 liter of water. The substrate was dispensed in 0.5-ml amounts into test tubes, and a turbid suspension was made with the test organism. The test was then incubated aerobically at 35 degrees C for 4 h. The development of a blue color was considered positive. A total of 345 strains of clinically isolated anaerobic bacteria were tested. All isolates of Bacteroides fragilis, Bacteroides thetaiotaomicron, Bacteroides uniformis. Clostridium perfringens, and Clostridium sordellii gave a positive reaction. Some isolates of Bacteroides distasonis and Bacteroides vulgatus were also positive. The use of this rapid test in conjunction with other rapid methods, such as the spot indol test, will enable laboratory workers to report these pathogens on the same day on which an inoculum of pure culture growth on agar is available.