Performance of Candida ID, a New Chromogenic Medium for Presumptive Identification of Candida Species, in Comparison to CHROMagar Candida

Candida ID agar allows identification of Candida albicans and differentiation of other Candida species. In comparison with CHROMagar Candida, we evaluated the performance of this medium directly from 596 clinical specimens. In particular, detection of C. albicans after 24 h of incubation was easier on Candida ID (sensitivity, 96.8%) than on CHROMagar (sensitivity, 49.6%)

Evaluation of Candida ID, a New Chromogenic Medium for Fungal Isolation and Preliminary Identification of Some Yeast Species

Candida ID, a new chromogenic medium, allows identification of Candida albicans (blue colonies) and preliminary identification into a group of four species (pink colonies). In comparison with Albicans ID2 and Sabouraud gentamicin chloramphenicol on 446 fungal strains, Candida ID allowed the isolation of more species than Albicans ID 2 (95.5% versus 91.2%)

Identification of Candida glabrata by a 30-Second Trehalase Test

Rapid (30-s) trehalase tests done with material from colonies of 482 yeasts suspended in a drop of trehalose solution on a commercially supplied glucose test strip were positive for 225 (99.1%) of 227 Candida glabrata isolates grown on either of two differential media, Candida ID medium or CandiSelect medium. The test was positive for only 3 (1.2%) and 12 (4.7%) of 255 isolates of other medically important yeast species grown on the same two media, respectively. A rapid maltase test done with a subset of 255 yeast isolates was negative for all but 1 of 64 trehalase-positive C. glabrata isolates, raising the specificity of the rapid testing for C. glabrata to 98.4 to 100%, depending on the isolation medium used. Rapid trehalase and maltase tests done independently in two laboratories with 217 yeast isolates showed sensitivities of 96.0 to 98.0% and specificities of 98.2 to 99.4% for identification of C. glabrata from colonies grown on Candida ID medium. The specificity was much lower because of frequent false-positive trehalose test results when the source of colonies was Sabouraud agar formulated with 4% glucose. We conclude that direct recognition of C. albicans as blue colonies on Candida ID isolation medium coupled with the performance of the 30-s trehalase and maltase tests for C. glabrata among the white colonies on this medium will allow the rapid presumptive identification of the two yeast species most commonly encountered in clinical samples

Alafosfalin as a Selective Agent for Isolation of Salmonella from Clinical Samples

The selectivity of a range of culture media for the detection of Salmonella was assessed using 435 strains of gram-negative bacteria. These media showed limited ability to inhibit non-Salmonella strains found in stool samples. We report the evaluation of alafosfalin as a selective agent for isolation of Salmonella from stool samples. Susceptibility studies with this agent showed that non-typhi Salmonella strains were relatively resistant (mean MIC, 10.2 mg/liter) compared to many coliforms including Escherichia coli (mean MIC, 0.7 mg/liter). A chromogenic medium, ABC medium, was modified to incorporate alafosfalin and was compared with standard ABC medium and Hektoen enteric agar for the isolation of Salmonella from 1,000 stool samples. On direct culture, modified ABC medium showed higher recovery of Salmonella (53.6%) compared with either ABC medium (35.7%) or Hektoen enteric agar (48.2%). We conclude that alafosfalin is a useful selective agent for the isolation of Salmonella from stool samples

Vancomycin treatment is a risk factor for vancomycin-nonsusceptible Staphylococcus capitis sepsis in preterm neonates

International audienceOBJECTIVES: Multidrug-resistant, vancomycin-nonsusceptible Staphylococcus capitis is an emerging cause worldwide of late-onset sepsis (LOS) in preterm neonates. The pathophysiology and risk factors for S.~capitis-related LOS are poorly understood, but we hypothesized that S.~capitis LOS follows translocation from the gut microbiota rather than catheter invasion. The objective of this study was to investigate the risk factors of S.~capitis LOS and gut colonization. METHODS: We conducted a prospective single-centre cohort study of patients hospitalized in a tertiary-care unit (Lyon, France) from June 2011 to January 2012. S.~capitis gut colonization was determined weekly from stool cultures. The determinants of gut colonization and LOS were established by multivariate Cox proportional hazards models. RESULTS: Eighty-three (36.2%) of 229 patients had S.~capitis-positive stool culture, and 28 (12.2%) developed S.~capitis LOS during hospitalization. Independent risk factors for S.~capitis LOS included prior administration of vancomycin independent of a previous LOS episode (hazard ratio 6.44, 95% confidence interval 2.15-19.3, p 0.001) and low birth weight (hazard ratio 0.72 per 100~g increase, 95% confidence interval 0.55-0.95, p 0.02). The prior administration of vancomycin was also an independent risk factor for S.~capitis colonization (hazard ratio 3.45, 95% confidence interval 2.07-5.76, p \textless0.001), particularly in the first week of life and in noncolonized neonates. CONCLUSIONS: Neonates treated with vancomycin are at a higher risk of LOS caused by vancomycin-nonsusceptible S.~capitis. The use of vancomycin in neonates must urgently be optimized to limit the selection of vancomycin-nonsusceptible strains, for which alternative antibiotics are lacking