Evaluation of a reformulated CHROMagar Candida

CHROMagar Candida is a differential culture medium for the isolation and presumptive identification of clinically important yeasts. Recently the medium was reformulated by Becton Dickinson. This study was designed to evaluate the performance of the new formula of CHROMagar against the original CHROMagar Candida for recovery, growth, and colony color with stock cultures and with direct plating of clinical specimens. A total of 90 stock yeast isolates representing nine yeast species, including Candida dubliniensis, as well as 522 clinical specimens were included in this study. No major differences were noted in growth rate or colony size between the two media for most of the species. However, all 10 Candida albicans isolates evaluated consistently gave a lighter shade of green on the new CHROMagar formulation. In contrast, all 26 C. dubliniensis isolates gave the same typical dark green color on both media. A total of 173 of the 522 clinical specimens were positive for yeast, with eight yeast species recovered. The recovery rates for each species were equivalent on both media, with no consistent species-associated differences in colony size or color. Although both media were comparable in performance, the lighter green colonies of C. albicans isolates on the new CHROMagar made it easier to differentiate between C. albicans and C. dubliniensis isolates. In conclusion, the newly formulated Becton Dickinson CHROMagar Candida medium is as equally suited as a differential medium for the presumptive identification of yeast species and for the detection of multiple yeast species in clinical specimens as the original CHROMagar Candida medium.     

Identification of Proteus penneri sp. nov., formerly known as Proteus vulgaris indole negative or as Proteus vulgaris biogroup 1.

The name Proteus penneri sp. nov. is proposed for a group of organisms previously called Proteus vulgaris indole negative or P. vulgaris biogroup 1. All of these strains were salicin negative, esculin negative, and chloramphenicol resistant (zone size, less than 14 mm). DNA relatedness studies indicated that when DNA from P. penneri strain 1808-73 was labeled and tested against unlabeled DNA from 13 other P penneri strains, a highly related group was formed (88 to 99% relatedness at 60 degrees C and 67 to 99% relatedness at 75 degrees C). Strain 1808-73 (ATCC 33519) is proposed as the type strain of P. penneri. In this study, two distinct groups of indole-positive P. vulgaris strains were also apparent. The first group (defined as P. vulgaris biogroup 2) was indole positive, salicin positive, and esculin positive, and the second group (defined as P. vulgaris biogroup 3) was indole positive, salicin negative, and esculin negative. The current type strain of P. vulgaris (ATCC 13315) belongs to biogroup 3. The DNA from P. penneri strains was not highly related to labeled DNA from the type strain of P. vulgaris (14 to 30% relatedness at 75 degrees C) or from P. vulgaris strain PR 1 (ATCC 29905), which belongs to biogroup 2 (27 to 33% relatedness at 75 degrees C). Strains of biogroup 2 were sensitive to chloramphenicol (zone size, greater than 19mm), and 10 of these strains formed a highly related group by DNA hybridization when DNA from PR 1 was labeled (64 to 100% relatedness at 60 degrees C and 70 to 100% relatedness at 75 degrees C), but they were not highly relatedness to the type strain of P. vulgaris (51 to 68% relatedness at 60 degrees C and 14 to 44% relatedness at 75 degrees C). Further DNA relatedness studies are needed on strains of biogroup 3 before a definitive taxonomic proposal can be made for these two indole-positive biogroups.     

Hormonal modulation of glomerular function

Glomeruli contain receptors for many hormones. Binding of angiotensin II (ANG II) or antidiuretic hormone (ADH) to glomerular mesangial cells elicits a contractile response. Other hormones induce synthesis of cyclic nucleotides (cAMP, cGMP). Glomeruli also synthesize several prostaglandins, renin, and ANG II. Micropuncture studies in Munich-Wistar rats have examined the effects of vasoactive drugs and hormones on the filtration process. Several vasodilators increase renal plasma flow in the dog and rat, but GFR remains relatively unchanged due to an offsetting fall in the ultrafiltration coefficient (Kf). Vasoconstrictor substances such as ANG II and norepinephrine cause declines in renal plasma flow and Kf, but GFR remains constant due to an increase in the transcapillary hydraulic pressure gradient. Antidiuretic peptides and parathyroid hormone also reduce Kf. Glomerular mesangial cells may regulate Kf by contracting and reducing glomerular capillary surface area. ANG II and ADH directly stimulate mesangial cell contraction in vitro. Other hormones appear to cause contraction by inducing local ANG II synthesis. These hormonal pathways are implicated in the pathogenesis of altered glomerular function in diverse forms of renal injury.     

Biochemical identification of Aeromonas genospecies isolated from humans

One hundred phenotypic characteristics were determined for 138 clinical and environmental Aeromonas strains. Cluster analysis revealed three major phenons equivalent to the A. hydrophila, A. caviae, and A. sobria groups, each of which contained more than one genospecies and more than one named species. An excellent correlation was found between phenotypic identification and classification based on DNA relatedness. DNA hybridization groups within each of the phenotypic groups were also separable by using a few biochemical characteristics. Key tests were production of acid from or growth on D-sorbitol (which separated DNA hybridization group 3 from groups 1 and 2 within the A. hydrophila phenogroup), growth on citrate (which essentially separated DNA hybridization group 4 from groups 5A and 5B within the A. caviae phenogroup), and growth on DL-lactate (which separated DNA hybridization group 1 from groups 2 and 3 within the A. hydrophila phenogroup as well as group 5A from groups 4 and 5B within the A. caviae phenogroup). All except one strain in the A. sobria phenogroup belonged to DNA hybridization group 8. DNA hybridization groups were not equally distributed among clinical and environmental isolates, suggesting that strains of certain DNA hybridization groups might be less virulent than others.     

Human serum antibody response to the presence of Aeromonas spp. in the intestinal tract.

A bacterial agglutination assay, a toxin-neutralizing assay, and an enzyme-linked immunosorbent assay (ELISA) were used to compare antibodies against intestinal Aeromonas strains in serum samples from healthy carriers (n = 6), from patients with acute (n = 15) or chronic (n = 8) gastroenteritis, from patients with gastroenteritis caused by other enteropathogenic bacteria (n = 3), and from healthy blood donors (n = 50). Evaluation of the bacterial agglutination assay showed that it was not very useful. The sensitivity of the ELISA in patients with acute or chronic aeromonas-associated diarrhea was 30% (7 of 23 patients were positive), whereas the specificity was 74% (13 of 50 healthy donors were positive). Positive results in the ELISA correlated with immunoglobulin M and immunoglobulin G responses to lipopolysaccharides of homologous Aeromonas strains, as determined by gel immunoradioassay and Western immunoblot analysis. The sera showed cross-reactions with heterologous Aeromonas strains and with Escherichia coli strains. The toxin-neutralizing assay was positive in 5 of 11 patients who had developed acute severe diarrhea associated with cytotoxin-producing Aeromonas strains (46% sensitivity), whereas only 3 of 50 healthy donors had low serum titers of cytotoxin-neutralizing antibodies (94% specificity). All five patients were over 60 years of age. Cytotoxin-neutralizing activity was not observed in the sera of other groups of patients with aeromonads in their feces. We concluded that the three different serologic assays were not consonant with one another and that only the toxin-neutralizing assay distinguished patients with acute diarrhea from other groups of patients.     

A psychiatric study of 247 liver transplantation candidates

This study prospectively evaluated 247 consecutive liver transplantation candidates for the presence of psychiatric disorders. While one-half did not meet DSM-III criteria for a psychiatric diagnosis, 18.6% had delirium, 19.8% had an adjustment disorder, 9% had alcohol abuse or dependence, 4.5% had major depression, and 2% had other drug abuse or dependence. Delirious subjects were significantly more likely to have a lower serum albumin, lower Mini-Mental State exam scores, higher Trailmaking Test scores (both A and B), and more dysrhythmia on electroencephalogram (EEG). In addition, while both delirious and nondelirious subjects were judged to have high levels of overall stress, those with delirium had significantly poorer adaptive functioning and lower occupational, family, and social scale ratings. Thus, while all liver transplant candidates are under substantial psychosocial stress and require psychosocial support, those identified as being delirious require particular attention because of their numerous cognitive, medical, and psychosocial problems.     

Bartonella clarridgeiae, a newly recognized zoonotic pathogen causing inoculation papules, fever, and lymphadenopathy (cat scratch disease).

Shortly after adopting a 6-week-old cat, a veterinarian was bitten on the left index finger. Within 3 weeks, he developed headache, fever, and left axillary lymphadenopathy. Initial blood cultures from the cat and veterinarian were sterile. Repeat cultures from the cat grew Bartonella-like organisms with lophotrichous flagella. Sera from the veterinarian were not reactive against Bartonella henselae, B. quintana, or B. elizabethae antigens but were seroreactive (reciprocal titer, 1,024) against the feline isolate. Sequential serum samples from the cat were reactive against antigens of B. henselae (titer, 1,024), B. quintana (titer, 128), and the feline isolate (titer, 2,048). Phenotypic and genotypic characterization of this and six additional feline isolates, including microscopic evaluation, biochemical analysis, 16S rRNA gene sequencing, DNA-DNA hybridization, and PCR-restriction fragment length polymorphism of the 16S gene, 16S-23S intergenic spacer region, and citrate synthase gene identified the isolates as B. clarridgeiae. This is the first report of cat scratch disease associated with B. clarridgeiae.     

Enterobacter asburiae sp. nov., a new species found in clinical specimens, and reassignment of Erwinia dissolvens and Erwinia nimipressuralis to the genus Enterobacter as Enterobacter dissolvens comb. nov. and Enterobacter nimipressuralis comb. nov.

Enterobacter asburiae sp. nov. is a new species that was formerly referred to as Enteric Group 17 and that consists of 71 strains, 70 of which were isolated from humans. Enterobacter asburiae sp. nov. strains gave positive reactions in tests for methyl red, citrate utilization (Simmons and Christensen's), urea hydrolysis, L-ornithine decarboxylase, growth in KCN, acid and gas production from D-glucose, and acid production from L-arabinose, cellobiose, glycerol (negative in 1 to 2 days, positive in 3 to 7 days), lactose, D-mannitol, alpha-methyl-D-glucoside, salicin, D-sorbitol, sucrose, trehalose, and D-xylose. They gave negative reactions in the Voges-Proskauer test and in tests for indole, H2S production, phenylalanine, L-lysine decarboxylase, motility, gelatin, utilization of malonate, lipase, DNase, tyrosine clearing, acid production from adonitol, D-arabitol, dulcitol, erythritol, i(myo)-inositol, melibiose, and L-rhamnose. They gave variable reactions in tests for L-arginine dihydrolase (25% positive after 2 days) and acid production from raffinose (69% positive after 2 days). Thirty-four Enterobacter asburiae sp. nov. strains were tested for DNA relatedness by the hydroxyapatite method with 32PO4-labeled DNA from the designated type strain (1497-78, ATCC 35953). The strains were 69 to 100% related in 60 degrees C reactions and 63 to 100% related in 75 degrees C reactions. Divergence within related sequences was 0 to 2.5%. Relatedness of Enterobacter asburiae sp. nov. to 84 strains of members of the Enterobacteriaceae was 5 to 63%, with closest relatedness to strains of Enterobacter cloacae, Erwinia dissolvens, Enterobacter taylorae, Enterobacter agglomerans, Erwinia nimipressuralis, and Enterobacter gergoviae. All strains tested were susceptible to gentamicin and sulfdiazine, and most were susceptible to chloramphenicol, colistin, kanamycin, nalidixic acid, carbenicillin and streptomycin. All strains were resistant to ampicillan, cephalothin, and penicillin, and most were resistant or moderately resistant to tetracycline. Enterobacter asburiae sp. nov strains were isolated from a variety of human sources, most prevalent of which were urine (16 strains), respiratory sources (15 strains), stools (12 strains), wounds (11 strains), and blood (7 strains). The clinical significance of Enterobacter aburiae is not known. As a result of this and previous studies, proposals are made to transfer Erwinia dissolvens and Erwinia nimipressuralis to the genus Enterobacter as Enterobacter dissolvens comb. nov. and Enterobacter nimipressuralis comb. nov., respectively.     

Effects of the Ebbinghaus figure on grasping are not only due to misjudged size

It is not evident how the small effects of the flankers of the Ebbinghaus figure on peak grip aperture (PGA) should be interpreted. One interpretation is that the flankers influence the estimated size, which in turn influences the grasp. If this interpretation is correct, then only the size-dependent aspects of the grasping movement should depend on the spatial positions of the flankers. An alternative interpretation is that the effect on grip aperture is caused by a change in judgement of the required precision, in which case various aspects of the grasping movement could be influenced by the size and position of the flankers. We presented subjects with a display consisting of a central disk surrounded by four large or small flankers. The array of circular flankers could be rotated by 45°. There were two tasks: to reproduce the perceived size of the central disk, and to grasp the central disk. As in other studies, the reproduced size and the PGA were both influenced by the size of the flankers. The effect on reproduced size settings was independent of the flankers spatial position. Nevertheless, the flankers position did influence the final grip aperture and the grip orientation at PGA and at movement offset. Because the flankers changed more than only the PGA, we conclude that the effect of the flankers on prehension cannot only be because of misjudgement of the size of the central disk.     

Legionella pneumophila serogroup Lansing 3 isolated from a patient with fatal pneumonia, and descriptions of L. pneumophila subsp. pneumophila subsp. nov., L. pneumophila subsp. fraseri subsp. nov., and L. pneumophila subsp. pascullei subsp. nov

Previous DNA relatedness and enzyme electrophoretic mobility studies indicated heterogeneity among strains of Legionella pneumophila serogroups 1, 4, 5, and Lansing 3 (a new, as yet unnumbered serogroup). In this study 60 L. pneumophila strains were studied by DNA hybridization (hydroxyapatite method) to assess their genomic relatedness. These strains were also studied biochemically and serologically to determine whether they formed one or more phenotypic groups. DNA relatedness studies identified three groups. DNA group 1 contained the type strain Philadelphia 1 and strains from serogroups 1 through 14 of L. pneumophila. The average relatedness of DNA group 1 strains was 88% at 60 degrees C with 1.1% divergence in related sequences and 85% at 75 degrees C. DNA group 2 contained strain Los Angeles 1, the reference strain of serogroup 4, and strains of serogroups 1, 4, 5, and Lansing 3, an unnumbered serogroup. Average relatedness of DNA group 2 strains was 84% at 60 degrees C with 0.7% divergence and 87% at 75 degrees C. Reciprocal relatedness of DNA groups 1 and 2 was approximately 67% at 60 degrees C with 6.0% divergence and 48% at 75 degrees C. DNA group 3 strains were in serogroup 5. They were 98% related at 60 degrees C with 0.5% divergence and 97% related at 75 degrees C. Reciprocal relatedness of DNA group 3 and DNA group 1 was approximately 74% at 60 degrees C with 5.3% divergence and 43% at 75 degrees C, and reciprocal relatedness of DNA groups 3 and 2 was 66% at 60 degrees C with 5.7% divergence and 55% at 75 degrees C. The DNA groups could not be separated biochemically or serologically or by cell wall fatty acid and isoprenoid quinone composition. Three subspecies of L. pneumophila are proposed to accommodate the three DNA groups: L. pneumophila subsp. pneumophila subsp. nov. for DNA group 1, L. pneumophila subsp. fraseri subsp. nov. for DNA group 2, and pneumophila subsp. pascullei subsp. nov. for DNA group 3.