Clinical relevance of Scedosporium spp. and Exophiala dermatitidis in patients with cystic fibrosis: A nationwide study.

An increased prevalence of various filamentous fungi in sputum samples of patients with cystic fibrosis (CF) has been reported. The clinical significance, however, is mostly unclear. The aim of this study was to investigate the clinical relevance of Scedosporium spp. and Exophiala dermatitidis from sputum samples of patients with CF in the Netherlands. In this cross-sectional study, all CF patients of the Dutch national CF registry who were treated at five of the seven recognized CF centers during a 3-year period were included. We linked clinical data of the national CF registry with the national Dutch filamentous fungal database. We investigated the association between clinical characteristics and a positive sputum sample for Scedosporium spp. and E. dermatitidis, using logistic regression. Positive cultures for fungi were obtained from 3787 sputum samples from 699 of the 1312 patients with CF. Scedosporium spp. was associated with severe genotype, CF-related diabetes, several microorganisms, and inhaled antibiotics. E. dermatitidis was associated with older age, female sex, and Aspergillus spp. CF patients with and without Scedosporium spp. or E. dermatitidis seemed comparable in body mass index and lung function. This study suggests that Scedosporium spp. and E. dermatitidis are probably no major pathogens in CF patients in the Netherlands. Greater understanding of epidemiologic trends, risk factors, and pathogenicity of filamentous fungi in the respiratory tracts of patients with CF is needed.

Pyomelanin Secretion in Madurella mycetomatis Interferes with Spectrophotometric Endpoint Reading Using the Sensititre YeastOne alamarBlue Assay but Not with Visual Endpoint Reading.

The use of the Sensititre YeastOne YO10 alamarBlue assay for the in vitro susceptibility testing of Madurella mycetomatis was evaluated in M. mycetomatis isolates with and without pyomelanin secretion. Pyomelanin secretion did not influence visual endpoint reading; however, it caused a shift in peak absorbance from 570 nm to 620 nm when read spectrophotometrically. Therefore, when choosing the method for endpoint reading, the presence of pyomelanin should be considered.

Unexpected mechanisms of resistance in Dutch Pseudomonas aeruginosa isolates collected during 14 years of surveillance.

Pseudomonas aeruginosa is one of the most important causes of infection in intensive care units (ICUs). It is intrinsically resistant to many antimicrobials and easily acquires additional resistance genes via horizontal gene transfer of mobile genetic elements. In this study, 1528 P. aeruginosa isolates obtained from a Dutch national surveillance programme between the years 1998-2011 were analysed for the presence of extended-spectrum ß-lactamase (ESBL) genes (blaCTX-M, blaSHV, blaTEM, blaBEL, blaPER, blaVEB and blaOXA-10) and metallo-ß-lactamase (MBL) genes (blaIMP, blaVIM and blaNDM). Of the ceftazidime-resistant isolates, 6.2% tested phenotypically positive for ESBL. Moreover, a Verona integron-encoded MBL (VIM) gene was found in 3.1% of isolates that were phenotypically resistant to imipenem and/or meropenem. Multilocus sequence typing (MLST) of ESBL-positive isolates indicated ST1216, ST111 and ST622, with all blaVIM-positive isolates belonging to the ST111 clone. Although the prevalence of ESBL and MBL phenotypes in this Dutch national surveillance collection of >1500 ICU P. aeruginosa isolates was very low, all VIM-producing isolates belonged to the high risk-associated, international, clonal complex CC111, and most ESBL-producing isolates belonged to clonal complexes known for their successful spread, e.g. CC111 and CC235. These data indicate that high-risk clones of P. aeruginosa were present in the Netherlands between 1998-2011 and probably spread unnoticed throughout Dutch hospitals.

Molecular characterization and phylogeny of Shiga toxin-producing Escherichia coli isolates obtained from two Dutch regions using whole genome sequencing.

Shiga toxin-producing Escherichia coli (STEC) is one of the major causes of human gastrointestinal disease and has been implicated in sporadic cases and outbreaks of diarrhoea, haemorrhagic colitis and haemolytic uremic syndrome worldwide. In this study, we determined the molecular characteristics and phylogenetic relationship of STEC isolates, and their genetic diversity was compared to that of other E. coli populations. Whole genome sequencing was performed on 132 clinical STEC isolates obtained from the faeces of 129 Dutch patients with gastrointestinal complaints. STEC isolates of this study belonged to 44 different sequence types (STs), 42 serogenotypes and 14 stx subtype combinations. Antibiotic resistance genes were more frequently present in stx1-positive isolates compared to stx2 and stx1 + stx2-positive isolates. The iha, mchB, mchC, mchF, subA, ireA, senB, saa and sigA genes were significantly more frequently present in eae-negative than in eae-positive STEC isolates. Presence of virulence genes encoding type III secretion proteins and adhesins was associated with isolates obtained from patients with bloody diarrhoea. Core genome phylogenetic analysis showed that isolates clustered according to their ST or serogenotypes irrespective of stx subtypes. Isolates obtained from patients with bloody diarrhoea were from diverse phylogenetic backgrounds. Some STEC isolates shared common ancestors with non-STEC isolates. Whole genome sequencing is a powerful tool for clinical microbiology, allowing high-resolution molecular typing, population structure analysis and detailed molecular characterization of strains. STEC isolates of a substantial genetic diversity and of distinct phylogenetic groups were observed in this study.

Thirteen years of antibiotic susceptibility surveillance of Pseudomonas aeruginosa from intensive care units and urology services in the Netherlands.

The purpose of this study was the evaluation of trends in the antimicrobial resistance of Pseudomonas aeruginosa from intensive care unit (ICU) patients and urology patients in the Netherlands. From 1998 to 2010, 1,927 consecutive P. aeruginosa isolates from ICU (n = 1,393) and urology service patients (n = 534) of 14 university and referral hospitals all over the Netherlands were collected and their susceptibility to relevant antibiotics was determined according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines. Over time, a significant upward trend in the resistance of P. aeruginosa strains collected from ICUs to piperacillin (1.2 % to 10.6 %, p = 0.0175), piperacillin-tazobactam (1.2 % to 12.1 %, p = 0.0008), ceftazidime (1.2 % to 7.8 %, p = 0.0064), cefepime (4.8 % to 6.4 %, p = 0.0166), imipenem (6 % to 19.1 %, p < 0.0001), meropenem (8.3 % to 17 %, p = 0.0022) and ciprofloxacin (13.1 % to 31.2 %, p = 0.0024) was observed, as was the prevalence of multi-resistance (1.2 % to 8.5 %, p = 0.0002). For P. aeruginosa isolates from the urology services, the resistance to imipenem increased (4.1 % to 7.8 %, p = 0.0006) and to ciprofloxacin it decreased (22.4 % to 18.8 %, p = 0.025). Like in other countries, in the Netherlands, an increase in multi-resistant Gram-negatives is observed, suggesting the presence and dissemination of several mechanisms of resistance. Our findings emphasise the importance of local surveillance for the setting up of local antibiotic guidelines and to support optimal empiric therapy. With the observed increase in multi-resistance, the direct testing of alternative antibiotics like polymyxins and fosfomycin is essential. Our data also illustrate the importance of adequate outbreak control measures.