Prospective study of IgM to Toxoplasma gondii on Beckman Coulter's Access(TM) immunoassay system and comparison with Zeus ELISA and gull IFA assays

We compared a new assay for Toxoplasma IgM on the Access analyzer (Beckman Coulter, Inc., Chaska, MN, USA), a random access instrument based on the principle of paramagnetic particle enzyme immunoassay with an enzyme-linked immunosorbent assay (ELISA) (Zeus Scientific, Inc., Raritan, NJ, USA) and an immunofluorescent assay (IFA) (Gull Laboratories, Inc., Salt Lake City, UT, USA). Four hundred fresh, unfrozen clinical samples from pregnant women (n = 154), HIV positive patients (n = 41), and patients in whom infection with Toxoplasma gondii was suspected (n = 200) were collected and assayed over a three month period. The specificity of the Access assay was compared to the consensus results. Results that were discrepant between the ELISA and IFA were resolved using a third IFA (Zeus). Once resolved, the specificity for the Access assay, the Zeus ELISA and the Gull IFA were 99.22%, 97.91%, and 99.45%, respectively. We conclude that the Access assay specificity is comparable to consensus results, minimizing false positive results; and because it is a random access instrument, it may be preferable over batch methods.

O:13a,13b, a new pathogenic serotype of Yersinia enterocolitica

Forty strains of a new Yersinia enterocolitica serotype isolated in the United States from nonhuman primates and humans were characterized as serotype O:13a,13b. Most of the human strains were isolated from a large multistate outbreak of milkborne enteritis. A common antigenic factor between this new serotype and four previously described Y. enterocolitica (O:7,13; O:18; O:44; and O:44,45) led to recharacterization of the latter as serotypes O:7,13a,13b; O:18,13b; O:44,13a; and O:44,13a,45.

Comparison of the suitability of three common bacterial media for susceptibility testing of trimethoprim-sulfamethoxazole

The in vitro inhibitory activity of trimethoprim-sulfamethoxazole is inversely related to the amount of thymine and thymidine in the test medium; manufacturers must adequately control their media to avoid spurious antimicrobial susceptibility results. No differences were observed when commercial Mueller-Hinton broth and agar were compared with a semisynthetic broth medium by the use of microdilution and disk diffusion techniques.

New latex agglutination test for rapid determination of rubella immune status

A prototype rubella latex agglutination card assay (Hynson, Westcott and Dunning, Baltimore, Md.) was compared with a standard hemagglutination inhibition test for the detection of rubella antibodies in 500 sera. The sensitivity and specificity of the latex agglutination assay were 100% and 94%, respectively. This assay did not require pretreatment of serum, and the entire assay could be performed in 10 min.

Comparison of several test systems used for determination of rubella immune status

Hemagglutination inhibition (HAI) is currently the most widely used technique for the determination of rubella immune status. However, two new methods, enzyme-linked immunosorbent assay (ELISA) and indirect immunofluorescence (FIAX), have also been adapted for this purpose. In comparing a commercially available ELISA system (BIO-BEAD, Litton Bionetics) with an HAI system (RUBA-tect, Abbott Laboratories), some ELISA-positive sera were found to be rubella antibody negative by the HAI system. To determine which of these results more accurately reflected the immune status of the patient, 74 RUBA-tect-negative sera were retested by ELISA BIO-BEAD, FIAX (International Diagnostic Technology) and by modified HAI, employing fresh erythrocytes (using Flow Laboratories reagents). Eleven RUBA-tect-negative sera (15%) were positive by ELISA, FIAX, and modified HAI. Two sera were positive only by ELISA and FIAX, two sera were positive by ELISA and HAI, four sera were positive by ELISA only, and one serum was positive by FIAX only. Neutralization assays were subsequently performed on sera positive by only one or two of the procedures to determine the presence of protective rubella antibodies in these sera; all but three of the sera were positive for neutralizing antibody. Commercial ELISA and FIAX systems appear to be more sensitive indicators of rubella immune status than are commercial HAI kits which use stabilized erythrocytes. Neither ELISA nor FIAX require extraction of serum; moreover, the ELISA BIO-BEAD test assay can be performed without an expensive instrument for reading.

Purulent pericarditis complicating systemic infection with Candida tropicalis

A patient with a purulent pericarditis due to Candida tropicalis is described. A 77-year-old woman undergoing chemotherapy for Hodgkin's disease was admitted to the hospital with a history of several febrile episodes. She was thought to be septic and was begun on broad-spectrum antibiotics, despite treatment, however, the patient expired. Among the multiple premortem blood, urine, and cerebrospinal fluid cultures, one blood culture yielded C. tropicalis 2 days postmortem. Autopsy revealed purulent pericarditis accompanied by endocarditis and myocarditis due to culture-proven C. tropicalis. This is the first reported case of purulent pericarditis complicating systemic infection with this organism and is indicative of the fulminant course of fungal pericarditis.

Rapid isolation of Yersinia spp. from feces

Direct plating or cold enrichment or both have been used to isolate Yersinia spp. from feces. Freeze-shock double enrichment and KOH treatment have been recommended for recovery of Yersinia enterocolitica from surface waters and food, respectively. These techniques were evaluated as alternatives for rapid recovery of Yersinia spp. from feces. Stool samples were homogenized in buffered saline and autoclaved. Escherichia coli. Klebsiella pneumoniae, and Pseudomonas aeruginosa were each added to the suspension at a final concentration of 1.5 x 10(6) colony-forming units per ml. Yersinia cells were then added to a final concentration of 1.5 x 10(3), 1.5 x 10(4), 1.5 x 10(5), or 1.5 x 10(6) colony-forming units per ml. A total of 21 strains of Y. enterocolitica, 2 of Yersinia kristensenii, and 1 each of Yersinia intermedia and Yersinia fredriksenii were tested. For freeze-shock double enrichment, seeded stool samples were frozen overnight (-70 degrees C), transferred successively to m-tetrathionate broth (6 h. 37 degrees C) and selenite broth (2 h 37 degrees C), and plated on MacConkey, salmonella-shigella, and cellobiose-arginine-lysine agars for quantitation. For KOH treatment, seeded stool samples were mixed with 0.5% KOH at a ratio of 1:2 for 2 min and plated as described above. E. coli, K. pneumoniae, and P. aeruginosa were virtually eliminated after either method was used. All Yersinia strains were recovered after KOH treatment even at the lowest initial concentration (1.5 x 10(3) colony-forming units per ml). However, after freeze-shock double enrichment, not all strains were retrievable, and those isolates which were recovered were grown only from samples containing the highest number of Yersinia strains (1.5 x 10(6) colony-forming units per ml). KOH treatment of stool samples seems to be a viable substitute for more protracted methods of recovering Yersinia spp.

Rapid detection and identification of Bacteroides fragilis and Bacteroides melaninogenicus by immunofluorescence

Bacteroides fragilis group and Bacteroides melaninogenicus group fluorescent-antibody kits were evaluated with 188 clinical specimens and 116 fresh aerobic and anaerobic bacterial isolates. Fluorescent-antibody and culture results corresponded in 88% of clinical specimens of the B. fragilis group and 94% of clinical specimens of the B. melaninogenicus group. There was greater than or equal to 90% correlation for both kits with colony smears. Antigen sharing by Bacteroides bivius, Bacteroides disiens, and B. melaninogenicus was demonstrated.

Corynebacterium group JK bacterial infection in a patient with an epicardial pacemaker

Septicemia caused by Corynebacteria group JK bacterium has previously been reported to occur in patients who have predisposing illness, such as neoplasms, ventriculoatrial shunt, or prosthetic valve. This study documents the case of an epicardial abscess caused by a Corynebacterium group JK organism in a 69-year-old woman who had an epicardial pacemaker.

Yersinia enterocolitica in adults with gastrointestinal disturbances: need for cold enrichment

In a survey of hospitalized adults, cold enrichment of feces resulted in an incidence rate of Yersinia enterocolitica equal to that of Salmonella spp. Y. enterocolitica was not recovered by routine procedures.

Arginine deprivation in KB cells. II. Characterization of the DNA synthesized during starvation

DNA synthesis in cells deprived of arginine was examined. Three lines of evidence indicated that tritiated thymidine ([3H]TdR) incorporation in arginine-starved cells was due to replicative rather than repair DNA synthesis. (a) When made in the presence of bromodeoxyuridine, the [3H]TdR-labeled DNA sedimented at hybrid density in isopycnic gradients. (b) As determined by the diphenylamine reaction, there was a 15% increase in the chemical amount of DNA per culture 30 h after arginine deprivation. (c) [3H]TdR incorporation was hydroxyurea-sensitive. Alkaline velocity sedimentation of the total DNA made during starvation revealed the existence of two distinct size classes: most of the DNA sedimented at a position analogous to that of control DNA, but 40% migrated one-third the distance of the bulk. After arginine restoration, these shorter pieces appeared to be chased into DNA of normal length; thus, one lesion in deprived cultures may cause an arrest in completion of DNA stretches to mature size. These findings, together with results of morphological studies of starved cells, suggest that changes induced by arginine deficiency effect the organization of nucleoproteins. These changes are reversible upon arginine restoration.

Arginine deprivation in KB cells. I. Effect on cell cycle progress

When exponentially growing KB cells were deprived of arginine, cell multiplication ceased after 12 h but viability was maintained throughout the experimental period (42-48 h). Although tritiated thymidine ([(3)H]TdR) incorporation into acid-insoluble material declined to 5 percent of the initial rate, the fraction of cells engaged in DNA synthesis, determined by autoradiography, remained constant throughout the starvation period and approximately equal to the synthesizing fraction in exponentially growing controls (40 percent). Continous [(3)H]TdR-labeling indicated that 80 percent of the arginine-starved cells incorporated (3)H at some time during a 48-h deprivation period. Thus, some cells ceased DNA synthesis, whereas some initially nonsynthesizing cells initiated DNA synthesis during starvation. Flow microfluorometric profiles of distribution of cellular DNA contents at the end of the starvation period indicated that essentially no cells had a 4c or G2 complement. If arginine was restored after 30 h of starvation, cultures resumed active, largely asynchronous division after a 16-h lag. Autoradiographs of metaphase figures from cultures continuously labeled with [(3)H]TdR after restoration indicated that all cells in the culture underwent DNA synthesis before dividing. It was concluded that the majority of cells in arginine-starved cultures are arrested in neither a normal G1 nor G2. It is proposed that for an exponential culture, i.e. from most positions in the cell cycle, inhibition of cell growth after arginine with withdrawal centers on the ability of cells to complete replication of their DNA.

Feasibility of screening for penicillinase-producing Neisseria gonorrhoeae from primary culture plates by using a rapid microacidometric test

We have shown that it is possible to screen for penicillinase-producing Neisseria gonorrhoeae directly from primary culture plates. Experiments involving the cocultivation of four genera of beta-lactamase-positive (beta-lac(+)) bacteria and a beta-lactamase-negative (beta-lac(-)) N. gonorrhoeae on modified Thayer-Martin medium indicated that suppressed or inhibited beta-lac(+) bacteria did not give false-positive results when isolated beta-lac(-) colonies of gonococci were tested. Colonies were assayed for beta-lac production by an adaptation of a microacidometric method in which bacteria could be tested before or after the addition of oxidase reagent.

Continued initiation of DNA synthesis in arginine-deprived Chinese hamster ovary cells

When exponentially growing CHO cells were deprived of arginine (Arg), cell multiplication ceased after 12 h, but initiation of DNA synthesis continued: after 48 h of starvation with continuous [3H]thymidine exposure, 85% of the population had incorporated label, as detected autoradiographically. Consideration of the distribution of exponential cells in the various cell cycle phases leads to a calculation that most cells in G1 at the time that Arg was removed, as well as those in S, engaged in some DNA synthesis during starvation. In contrast, isoleucine (Ile)-starved cells did not initiate DNA synthesis, as has been reported by others. Experiments with cells synchronized by mitotic selection confirmed this difference in Arg- and Ile- deprived behavior, but also showed that cells which underwent the mitosis leads to G1 transition during Arg starvation remained arrested in G1 (G0?). The results suggest that Arg-deprived cells continue to maintain some proliferative function(s) while Ile-deprived cells do not.