The detection of bacterial and parasitic gastrointestinal pathogens through culture and microscopy is laborious and time-consuming. We evaluated a molecular screening approach (MSA) for the detection of five major enteric pathogens: Salmonella enterica, Campylobacter jejuni, Giardia lamblia, Shiga toxin-producing Escherichia coli (STEC), and Shigella spp./enteroinvasive E. coli (EIEC), for use in the daily practice of a clinical microbiology laboratory. The MSA consists of prescreening of stool specimens with two real-time multiplex PCR (mPCR) assays, which give results within a single working day, followed by guided culture/microscopy of the positive or mPCR-inhibited samples. In the present 2-year overview, 28,185 stool specimens were included. The MSA was applied to 13,974 stool samples (49.6%), whereas 14,211 samples were tested by conventional methods only (50.4%). The MSA significantly increased the total detection rate compared to that of conventional methods (19.2% versus 6.4%). The detection of all included pathogens, with the exception of S. enterica, significantly improved. MSA detection frequencies were as follows: C. jejuni, 8.1%; G. lamblia, 4.7%; S. enterica, 3.0%; STEC, 1.9%; and Shigella spp./EIEC, 1.4%. The guided culture/microscopy was positive in 76.8%, 58.1%, 88.9%, 16.8%, and 18.1% of mPCR-positive specimens, respectively. Of all mPCRs, only 1.8% was inhibited. Other findings were that detection of mixed infections was increased (0.9% versus 0.02%) and threshold cycle (C T ) values for MSA guided culture/microscopy-positive samples were significantly lower than those for guided culture/microscopy-negative samples. In conclusion, an MSA for detection of gastrointestinal pathogens resulted in markedly improved detection rates and a substantial decrease in time to reporting of (preliminary) results.
We have evaluated the use of a broad-range PCR aimed at the 16S rRNA gene in detecting bacterial meningitis in a clinical setting. To achieve a uniform DNA extraction procedure for both gram-positive and gram-negative organisms, a combination of physical disruption (bead beating) and a silica-guanidiniumthiocyanate procedure was used for nucleic acid preparation. To diminish the risk of contamination as much as possible, we chose to amplify almost the entire 16S rRNA gene. The analytical sensitivity of the assay was approximately 1 ؋ 10 2 to 2 ؋ 10 2 CFU/ml of cerebrospinal fluid (CSF) for both gram-negative and grampositive bacteria. In a prospective study of 227 CSF samples, broad-range PCR proved to be superior to conventional methods in detecting bacterial meningitis when antimicrobial therapy had already started. Overall, our assay showed a sensitivity of 86%, a specificity of 97%, a positive predictive value of 80%, and a negative predictive value of 98% compared to culture. We are currently adapting the standard procedures in our laboratory for detecting bacterial meningitis; broad-range 16S ribosomal DNA PCR detection is indicated when antimicrobial therapy has already started at time of lumbar puncture or when cultures remain negative, although the suspicion of bacterial meningitis remains.
The aim of this study was to develop an easy-to-use culture-free diagnostic method based on next generation sequencing (NGS) of PCR amplification products encompassing whole 16S-23S rRNA region to improve the resolution of bacterial species identification. To determine the resolution of the new method 67 isolates were subjected to four identification methods: Sanger sequencing of the 16S rRNA gene; NGS of the 16S-23S rRNA region using MiSeq (Illumina) sequencer; Microflex MS (Bruker) and VITEK MS (bioMérieux). To evaluate the performance of this new method when applied directly on clinical samples, we conducted a proof of principle study with 60 urine samples from patients suspected of urinary tract infections (UTIs), 23 BacT/ALERT (bioMérieux) positive blood culture bottles and 21 clinical orthopedic samples. The resolution power of NGS of the 16S-23S rRNA region was superior to other tested identification methods. Furthermore, the new method correctly identified pathogens established as the cause of UTIs and blood stream infections with conventional culture. NGS of the 16S-23S rRNA region also showed increased detection of bacterial microorganisms in clinical samples from orthopedic patients. Therefore, we conclude that our method has the potential to increase diagnostic yield for detection of bacterial pathogenic species compared to current methods.
Purpose: This Phase I study was designed to determine the maximum tolerated dose, profile of adverse events, and dose-limiting toxicity of AP5280 in patients with solid tumors. Furthermore, the platinum (Pt) pharmacokinetics after AP5280 administration and preliminary antitumor activity were evaluated. AP5280 is a Pt agent linked to the water-soluble, biocompatible copolymer N-(2-hydroxypropyl)methacrylamide, which potentially increases Pt accumulation in tumors via the enhanced permeability and retention effect. In this way, it is anticipated that a higher activity of therapeutic Pt can be reached. The pharmaceutical product contains approximately 8.5% of Pt by weight and has a molecular weight of approximately 25,000.Experimental Design: Adult patients with solid tumors received AP5280 as a 1-h i.v. infusion every 21 days. Pharmacokinetics of total and unbound Pt were determined during the first treatment course and before the start of each new cycle using noncompartmental pharmacokinetic analysis. Pt-DNA adduct concentrations in WBCs and, if available, in tumor tissue were quantified using a sensitive 32 P postlabeling assay.Results: Twenty-nine patients were treated at eight dose levels (90 -4500 mg Pt/m 2 ). The dose-limiting toxicity was Common Toxicity Criteria grade 3 vomiting and was experienced at 4500 mg Pt/m 2 in two of six patients. The maximum tolerated dose on this schedule was therefore 4500 mg Pt/m 2 , and the recommended dose for a Phase II study is 3300 mg Pt/m 2 . Renal toxicity and myelosuppression, toxicities typically observed with cisplatin and carboplatin, were minimal for AP5280. The area under the curve of total Pt increased with increasing AP5280 dose. Plasma clearance of total Pt was 644 ؎ 266 ml/h, and the terminal half-life was 116 ؎ 46.2 h. After AP5280 administration, Pt-guanineguanine DNA adduct concentrations in WBCs ranged from 70 to 1848 amol/g DNA, concentrations that were substantially lower than concentrations measured after administration of therapeutic doses of cisplatin.Conclusions: AP5280 can be administered safely as a 1-h i.v. infusion at a dose of 3300 mg Pt/m 2 once every 3 weeks and produces prolonged plasma exposure compared with any of the free Pt-containing drugs. However, it remains to be determined whether AP5280 can actually increase Pt delivery to the DNA of tumor cells in man as has been shown in experimental models.
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.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.