New identification characteristics of methicillin-resistant Staphylococcus aureus on chromogenic culture media.

Methicillin-Resistant Staphylococcus aureus (MRSA) is one of the most common and important causes of nosocomial infections. Rapid detection of this pathogen is important for conducting good and swift infection control. This prospective study evaluates two chromogenic media for the detection of MRSA. New colony characteristics were noticed during this evaluation: (i) a yellow/golden colouration on a pipette after streaking the colonies of the chromogenic culture could eventually be used as a supplementary identification test to identify the MRSA strains, and (ii) some MRSA strains do not metabolise the chromogens and therefore are not coloured on chromogenic agars. However, they have a typical yellow/golden colony aspect usually observed amongst S. aureus.

Zygomycosis in the immunocompromised patient: a case report.

Zygomycosis is a highly aggressive infection observed in immunocompromised patients, such as those with haematological malignancies. The sites most frequently involved are the sinuses and the lungs. New diagnostic tools and new antifungal treatments are essential in order to diagnose early and treat efficiently infections due to moulds. We report a case of sinusitis due to Absidia corymbifera occurring during chemotherapy-induced bone marrow aplasia in a patient with acute leukaemia. The sinusitis was successfully treated with AmBisome, and surgical debridement.

Comparison of different methods of isolation of DNA of commonly encountered Candida species and its quantitation by using a real-time PCR-based assay.

Molecular diagnosis based on genomic amplification methods such as real-time PCR assay has been reported as an alternative to conventional culture for early detection of invasive candidiasis. However, a major limitation of the molecular method is the difficulty associated with breaking fungal cell walls since the DNA extraction step still requires more than half of a working day. It has been suggested that PCR detection of free template DNA in serum is preferred over the use of whole blood for the diagnosis of systemic candidiasis. In this study, two conventional procedures (the first [the HLGT method] consists of boiling sera in an alkaline guanidine-phenol-Tris reagent, and the second [the PKPC method] uses proteinase K digestion, followed by organic extraction) and three commercially available kits for DNA isolation were evaluated for sensitivity, purity, cost, and use of template for most clinically important Candida species in a TaqMan-based PCR assay. To optimize these procedures, we evaluated the effect of adding 0.5% bovine serum albumin to DNA extracts and found that it decreased the effects of inhibitors. The QIAamp DNA blood kit did significantly shorten the duration of the DNA isolation but was among the most expensive procedures. Furthermore, the QIAamp DNA blood kit proved to be as sensitive as the HLGT DNA isolation method for PCR amplification from 52 serum samples from hematology or oncology patients with clinically proven or suspected systemic Candida infections. All PCR-positive samples showed approximately the same Candida species load by both procedures (100% correspondence), whereas one discordant result was obtained between PCR and blood culture.