Outbreak of Arcanobacterium haemolyticum in chronic wounds in The Netherlands.

INTRODUCTION: Aging and comorbidities such as diabetes and vascular problems contribute to the increasing occurrence of chronic wounds. From the beginning of 2016, a marked increase in Arcanobacterium haemolyticum (ARH) in chronic wound cultures was noted among patients visiting a wound expertise centre in The Netherlands. AIM: To report the outbreak investigation of ARH cultured from chronic wounds and describe the implemented infection prevention measures. METHODS: In total, 50 ARH isolates were sent to a reference laboratory for molecular typing. Samples for bacterial culture and ARH polymerase chain reaction were taken from care workers, the environment and items used for wound care. Infection prevention measures were implemented in a bundled approach, involving education, better aseptic wound care conditions and hygienic precautions. Before and after the implementation of infection prevention measures, two screening rounds of ARH testing were performed among all patients receiving home care. RESULTS: ARH isolates from wound care patients were found to be identical by core genome multi-locus sequence typing. No definite outbreak source could be determined by culture. However, three pairs of forceps, used by two nurses on multiple patients, were found to be ARH positive by polymerase chain reaction. In the two screening rounds before and after the implementation of infection prevention measures, the proportion of ARH-positive patients decreased significantly from 20% (20/99) to 3% (3/104). Subsequently, no new cases occurred. CONCLUSION: This first ARH outbreak was likely caused by re-using contaminated instruments. Through the implementation of improved infection prevention measures and re-education of all employees involved, the outbreak was controlled. With the current trend of care transition, infection control must be a major concern.

Evaluation of three enzyme immunoassays and a loop-mediated isothermal amplification test for the laboratory diagnosis of Clostridium difficile infection.

The laboratory diagnosis of Clostridium difficile infection (CDI) consists of the detection of toxigenic Clostridium difficile, and/or its toxins A or B in stool preferably in a two-step algorithm. In a prospective study, we compared the performance of three toxin enzyme immunoassays (EIAs)-ImmunoCard Toxins A & B, Premier Toxins A & B and C. diff Quik Chek Complete, which combines a toxins test and a glutamate dehydrogenase (GDH) antigen EIA in one device -and the loop-mediated isothermal amplification assay Illumigene C. difficile. In total 986 stool samples were analyzed. Compared with toxigenic culture as the gold standard, sensitivities, specificities, PPV and NPV values of the toxin EIAs were 41.1-54.8 %, 98.9-100 %, 75.0-100 % and 95.5-96.5 % respectively, of the Illumigene assay 93.3 %, 99.7 %, 95.8 % and 99.5 %. Illumigene assays performed significantly better for non-014/020 PCR-ribotypes than for C. difficile isolates belonging to 014/020. Discrepant analysis of three culture-negative, but Illumigene-positive samples, revealed the presence of toxin genes using real-time PCRs. In addition to the GDH EIA (NPV of 99.8 %), the performance of Illumigene allows this test to be introduced as a first screening test for CDI- or as a confirmation test for GDH -positive samples, although the initial invalid Illumigene result of 4.4 % is a point of concern.

Comparison of two commercial molecular assays for simultaneous detection of respiratory viruses in clinical samples using two automatic electrophoresis detection systems.

Two molecular assays were compared with real-time RT-PCR and viral culture for simultaneous detection of common viruses from respiratory samples: a multiplex ligation-dependant probe amplification (MLPA) and a dual priming oligonucleotide system (DPO). In addition, the positive detections of MLPA and DPO were identified using two different automatic electrophoresis systems. A panel of 168 culture-positive and negative samples was tested by the molecular assays for the presence of influenza A and B virus, respiratory syncytial virus, human metapneumovirus, rhinovirus, coronaviruses, parainfluenza viruses and adenovirus. One hundred and twenty-nine (77%) samples were positive as detected by at least one method. Sixty-nine (41%) samples were positive by cell culture (excluding human metapneumovirus and coronaviruses), 116 (69%) by RT-PCR, 127 (76%) by MLPA and 100 (60%) by DPO. The MLPA yielded results in one attempt for all samples included while 12 (7.2%) samples had to be repeated by the DPO assay due to inconclusive results. The MLPA assay performed well in combination with either electrophoresis system, while the performance of the DPO assay was influenced by the electrophoresis systems. Both molecular assays are comparable with real-time RT-PCR, more sensitive than viral culture and can detect dual infections easily. Results can be obtained within 1 day.

Parasitological diagnosis combining an internally controlled real-time PCR assay for the detection of four protozoa in stool samples with a testing algorithm for microscopy.

Molecular detection of gastrointestinal protozoa is more sensitive and more specific than microscopy but, to date, has not routinely replaced time-consuming microscopic analysis. Two internally controlled real-time PCR assays for the combined detection of Entamoeba histolytica, Giardia lamblia, Cryptosporidium spp. and Dientamoeba fragilis in single faecal samples were compared with Triple Faeces Test (TFT) microscopy results from 397 patient samples. Additionally, an algorithm for complete parasitological diagnosis was created. Real-time PCR revealed 152 (38.3%) positive cases, 18 of which were double infections: one (0.3%) sample was positive for E. histolytica, 44 (11.1%) samples were positive for G. lamblia, 122 (30.7%) samples were positive for D. fragilis, and three (0.8%) samples were positive for Cryptosporidium. TFT microscopy yielded 96 (24.2%) positive cases, including five double infections: one sample was positive for E. histolytica/Entamoeba dispar, 29 (7.3%) samples were positive for G. lamblia, 69 (17.4%) samples were positive for D. fragilis, and two (0.5%) samples were positive for Cryptosporidium hominis/Cryptosporidium parvum. Retrospective analysis of the clinical patient information of 2887 TFT sets showed that eosinophilia, elevated IgE levels, adoption and travelling to (sub)tropical areas are predisposing factors for infection with non-protozoal gastrointestinal parasites. The proposed diagnostic algorithm includes application of real-time PCR to all samples, with the addition of microscopy on an unpreserved faecal sample in cases of a predisposing factor, or a repeat request for parasitological examination. Application of real-time PCR improved the diagnostic yield by 18%. A single stool sample is sufficient for complete parasitological diagnosis when an algorithm based on clinical information is applied.