MRSA in Austria--an overview.

The aim of this study was to provide an overview of predominant and sporadic methicillin-resistant Staphylococcus aureus (MRSA) strains in large regions of Austria, and to compare the results with those from other European countries. In total, 1439 MRSA isolates, collected routinely between January 1996 and June 2006 from five Austrian federal provinces, were investigated. The isolates were confirmed as MRSA using mecA/femA multiplex PCR assays. Genes encoding Panton-Valentine leukocidin (PVL), which are characteristic of community-acquired MRSA, were also detected by PCR. Subtyping was performed using SmaI macrorestriction digestion of genomic DNA, followed by pulsed-field gel electrophoresis (PFGE) and cluster analysis. Isolates that could not be assigned to clusters were further analysed by spa typing and/or multilocus sequence typing. The predominant clones detected in Austria were ST228 (southern German epidemic clone), ST5 (Rhine-Hessen MRSA), the ST8 Austrian clone and CC8/ST8. Whereas the frequencies of lineages corresponding to ST247, ST45 and ST22 remained comparably low, an increase in the frequency of lineages corresponding to ST5 and to ST228 was recorded. Overall, 20 different MRSA types and 321 subtypes were recognised according to PFGE analysis. The prevalence of different strains varied considerably in the different Austrian regions. When compared to other European countries, the situation in Austria was most similar to that found in Germany.

PVL-positive MRSA in Austria.

The objective of this study was to present, for the first time, an overview of the existing Panton-Valentine leukocidin (PVL)-positive methicillin-resistant Staphylococcus aureus (MRSA) strains in Austria and to compare the situation with that found in other countries. Between 2001 and 2006 we analysed 1150 MRSA isolates - from infections as well as from colonisation - for the presence of PVL genes. The most common multilocus sequence types of the 94 PVL-positive MRSA strains were ST8, ST152, ST30, ST80, and ST5; the ST22, and ST777 sequences were also detected. During 2005 and 2006, 3.7-7.7% of the isolates were PVL-positive. The age distribution of the patients revealed that nosocomial MRSA mainly occurs in elderly people, whereas PVL-positive MRSA mainly appears in younger people. We observed a relatively high prevalence of PVL-positive isolates. Several MRSA clones containing the PVL genes are spreading throughout Austria, including two strains not yet widespread in Western Europe.

Prospective study of the performance of vibrational spectroscopies for rapid identification of bacterial and fungal pathogens recovered from blood cultures.

Rapid identification of microbial pathogens reduces infection-related morbidity and mortality of hospitalized patients. Raman spectra and Fourier transform infrared (IR) spectra constitute highly specific spectroscopic fingerprints of microorganisms by which they can be identified. Little biomass is required, so that spectra of microcolonies can be obtained. A prospective clinical study was carried out in which the causative pathogens of bloodstream infections in hospitalized patients were identified. Reference libraries of Raman and IR spectra of bacterial and yeast pathogens highly prevalent in bloodstream infections were created. They were used to develop identification models based on linear discriminant analysis and artificial neural networks. These models were tested by carrying out vibrational spectroscopic identification in parallel with routine diagnostic phenotypic identification. Whereas routine identification has a typical turnaround time of 1 to 2 days, Raman and IR spectra of microcolonies were collected 6 to 8 h after microbial growth was detected by an automated blood culture system. One hundred fifteen samples were analyzed by Raman spectroscopy, of which 109 contained bacteria and 6 contained yeasts. One hundred twenty-one samples were analyzed by IR spectroscopy. Of these, 114 yielded bacteria and 7 were positive for yeasts. High identification accuracy was achieved in both the Raman (92.2%, 106 of 115) and IR (98.3%, 119 of 121) studies. Vibrational spectroscopic techniques enable simple, rapid, and accurate microbial identification. These advantages can be easily transferred to other applications in diagnostic microbiology, e.g., to accelerate identification of fastidious microorganisms.

HLA-C locus antigens seen by one-dimensional isoelectric focusing: definition of the so far known HLA-C specificities and of two subtypes.

A panel of homozygous typing cells was employed for biochemical definition of all known HLA-C locus antigens from Cw1 through Cw11. Each HLA-C antigen yielded, after precipitation with one of the monoclonal antibodies W6/32, 4E, or HC10, a specific banding pattern on one-dimensional isoelectric focusing gels. In addition, two biochemical subtypes of Cw1 and Cw7 could be identified. These biochemical HLA-C "splits" were characterized not only by different isoelectric points but also by strong linkage disequilibriums with certain HLA-B antigens.

Biochemical HLA typing: a population study in 112 Caucasians.

In order to define frequencies and associations of biochemically defined HLA-A and -B specificities and their variants and subtypes in a Caucasian population, biochemical HLA typing was performed in a panel of 112 Austrians. Already known rare variants of HLA-A2, A3, A30, Aw33 and B39 and the more frequent subtypes of HLA-B27, B35, B44 and, in addition, a so far unknown variant of HLA-B18 were present in the panel. Family segregation analyses of the biochemically defined HLA class I variants revealed that they could be found only in certain rare haplotypes, most of them in high linkage disequilibrium. The basic variant of HLA-A30, for example, obviously occurred only in the HLA-A30, B49, Cw7 haplotype, similar to the Aw33 acidic variant, which was exclusively found in the Aw33, Bw58, Cw3 haplotype. None of the biochemical variants was found in frequent common haplotypes.

HLA-C "blank" alleles express class I gene products. Biochemical analysis of four different HLA-C "blank" polypeptides.

Monoclonal antibodies (mAbs) W6/32, HC10, and 4E were used to precipitate class I antigens from 21 selected individuals with at least one HLA-C "blank" allele. In 19 of these individuals, characteristic HLA-C banding patterns which could be precipitated by all three HLA class I mAbs were observed on one-dimensional isoelectric focusing gels--obviously the gene products of HLA-C "blank". At least four allelic HLA-C "blank" gene products with different isoelectric points could be discerned. All of them segregated with HLA-C "blank" haplotypes in informative families; two of them were associated with HLA-B51, one with HLA-B38, and one with HLA-B18. Reactivity of the HLA-C "blank" heavy chains with mAb W6/32 indicates that they are able to associate with beta-2 microglobulin, and hence are most probably expressed at the cell surface.