Anneke Bergmans

Designation of the European Working Group on Legionella infection (EWGLI) amplified fragment length polymorphism types of Legionella pneumophila serogroup 1 and results of intercentre proficiency testing using a standard protocol

Abstract.The utility of amplified fragment length polymorphism (AFLP) analysis as a genotyping method for the epidemiological typing of Legionella pneumophila serogroup 1 has been previously demonstrated. This study (i) reports recommendations for the designation of the European Working Group on Legionella Infections (EWGLI) AFLP types, (ii) describes the EWGLI AFLP types identified for the 130 strains in the EWGLI culture collection, and (iii) reports the results of a newly introduced international programme of proficiency testing. Following preliminary analysis of 20 epidemiologically unrelated isolates, 16 major AFLP types were identified. A coded proficiency panel, comprising 12 additional isolates representing 9 of these 16 AFLP types, was sent to 17 centres in 14 European countries where it was analysed following a previously determined standard protocol. The identity of each coded strain (recorded as AFLP type 001–016 or untypeable) was determined by participants with reference to these 16 AFLP types, either visually or using gel analysis software where available, and reported to the coordinating centre. Nine of the 12 strains, including an epidemiologically related pair and two pairs of unrelated isolates of the same type, were correctly identified to the correct AFLP type by all or all but one of the participants. Seven laboratories correctly identified all 12 isolates, and a further seven laboratories correctly identified 11. Type identification scores ranged from 75% (1 centre), 83% (2 centres), and 92% (7 centres) to 100% (7 centres). The AFLP method as described is robust and rapid and allows the genotypic comparison of isolates of Legionella pneumophila between different testing centres without the need for exchange of the strains studied.

Novel PCR-probe assay for detection of and discrimination between Legionella pneumophila and other Legionella species in clinical samples.

In recent years, several PCR-based methods for detection of Legionella DNA have been described, but all PCR assays commonly lacked the ability to discriminate between Legionella pneumophila and other Legionella species ([1][1]-[3][2], [5][3]). A recent study indicated that Legionella species other

Recent emergence of Staphylococcus aureus clonal complex 398 in human blood cultures.

Background Recently, a clone of MRSA with clonal complex 398 (CC398) has emerged that is related to an extensive reservoir in animals, especially pigs and veal calves. It has been reported previously that methicillin-susceptible variants of CC398 circulate among humans at low frequency, and these have been isolated in a few cases of bloodstream infections (BSI). The purpose of this study was to determine the prevalence of S. aureus CC398 in blood cultures taken from patients in a geographic area with a high density of pigs. Methodology/Principal Findings In total, 612 consecutive episodes of S. aureus BSI diagnosed before and during the emergence of CC398 were included. Three strains (2 MSSA and 1 MRSA) that were isolated from bacteremic patients between 2010–2011 were positive in a CC398 specific PCR. There was a marked increase in prevalence of S. aureus CC398 BSI isolated between 2010–2011 compared to the combined collections that were isolated between 1996–1998 and 2002–2005 (3/157, 1.9% vs. 0/455, 0.0%; p = 0.017). Conclusions/Significance In conclusion, in an area with a relative high density of pigs, S. aureus CC398 was found as a cause of BSI in humans only recently. This indicates that S. aureus CC398 is able to cause invasive infections in humans and that the prevalence is rising. Careful monitoring of the evolution and epidemiology of S. aureus CC398 in animals and humans is therefore important.

Correlation between detection methods of Chlamydia pneumoniae in atherosclerotic and non-atherosclerotic tissues.

Polymerase chain reaction (PCR) and immunohistochemistry (IHC) have been used to detect Chlamydia (C.) pneumoniae in vascular tissues. Discrepancies between the results of these two methods have frequently been reported. However, the correlation between PCR and IHC has not been analyzed yet. This study assesses the correlation between the detection of C. pneumoniae by PCR and IHC in 45 atherosclerotic and 50 non-atherosclerotic tissue specimens. Also, the presence of Mycoplasma (M.) pneumoniae in these 95 specimens was investigated. Correlation was found between the detection of C. pneumoniae by PCR and IHC in the atherosclerotic tissues. Both tests were positive in 10 specimens and negative in 17 specimens (p = 0.003). There was no significant correlation between PCR and IHC in non-atherosclerotic specimens (p = ns). M. pneumoniae was detected, by PCR, in one atherosclerotic specimen.The results show correlation between PCR and IHC in the detection of C. pneumoniae in atherosclerotic tissues, emphasize the association between C. pneumoniae and atherosclerosis, and support the specificity of the association between C. pneumoniae and atherosclerosis.

Characterization of Actinomyces turicensis and Actinomyces radingae strains from human clinical samples

Whole-organism protein electrophoresis was used to compare and group unidentified coryneform bacteria resembling Gardnerella vaginalis and various Actinomyces and Arcanobacterium species. The obtained clusters of strains were further characterized by whole-cell fatty acid analysis and a variety of biochemical tests. Species-specific oligonucleotide probes based on 16S rRNA gene sequences were designed. The results demonstrate that the majority of the isolates belonged to Actinomyces turicensis; the other strains belonged to Actinomyces radingae. The descriptions of both species are emended.

Evaluation of a commercial real-time PCR for the detection of extended spectrum β-lactamase genes.

We investigated the performance of a real-time PCR for the detection of extended spectrum β-lactamase genes in Enterobacteriaceae (Check-MDR ESBL PCR). Results from micro-arrays were considered as the gold standard. An analysis on 489 isolates resulted in a sensitivity of 98.9 % and a specificity of 100 % for the PCR.