Infectious diseases caused by bacterial pathogens are a worldwide burden. Serious bacterial infection-related complications, such as sepsis, affect over a million people every year with mortality ...rates ranging from 30% to 50%. Crucial clinical microbiology laboratory responsibilities associated with patient management and treatment include isolating and identifying the causative bacterium and performing antibiotic susceptibility tests (ASTs), which are labor-intensive, complex, imprecise, and slow (taking days, depending on the growth rate of the pathogen). Considering the life-threatening condition of a septic patient and the increasing prevalence of antibiotic-resistant bacteria in hospitals, rapid and automated diagnostic tools are needed. This review summarizes the existing commercial AST methods and discusses some of the promising emerging AST tools that will empower humans to win the evolutionary war between microbial genes and human wits.
In January 2014, severe haze episodes which sweep across Chinese cities have attracted public concern and interest at home and abroad. In addition to the physicochemical properties of air pollutants, ...bacteria are thought to be responsible for the spread of respiratory diseases and various allergies. We attempted the bacterial characterization of submicron particles (PM0.18–0.32, PM0.32–0.56, and PM0.56–1) under severe haze episodes using high-throughput sequencing and real-time quantitative PCR detecting system based on 21 samples collected from January to March 2014 at Ji'nan, China. The high bacterial concentration in PM0.32–0.56 (7314cells m−3), PM0.18–0.32 (7212cells m−3), and PM0.56–1 (6982cells m−3) showed significant negative correlations with SO2, NO2, and O3. Under sufficient sequencing depth, 37 phyla, 71 classes, 137 orders, 236 families, and 378 genera were classified, and the bacterial community structure varied significantly in different size fractions. For example, Holophagaceae (Acidobacteria) in PM0.32–0.56 showed 6-fold higher abundance than that in PM0.18–0.32. Moreover, functional categories and bacterial species (Lactococcus piscium, Pseudomonas fragi, Streptococcus agalactiae, and Pseudomonas cichorii) that may potentially be responsible for infections and allergies were also discovered. Source track analysis showed that the ambient bacteria mainly originated from soils, leaf surfaces, and feces. Our results highlighted the importance of airborne microbial communities by understanding the concentration, structure, ecological and health effects, especially those in submicron particles during haze episodes.
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•High bacterial concentration and diverse bacterial community in submicron particles during haze episodes were observed.•The bacterial community varied significantly via different size fractions.•Source track analysis showed that the ambient bacteria mainly originated from soils, leaf surfaces, and feces.
As a new type of environmental pollutant, microplastics (MPs) can adsorb residual organochlorine pesticides (OCPs) in the soil and pose a severe threat to the soil ecosystems. To understand the ...interaction between soil MPs and OCPs, the sorption of two kinds of OCPs, including hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs), on polyethylene (PE) microplastics in soil suspension was studied through sorption kinetics and isotherm models. The effects of solution/soil ratio and MPs diameter on sorption were examined. The kinetic experiment results show that the sorption equilibrium was 12 h， and the sorption process of OCPs on MPs can be well described by a pseudo-second-order model. The Freundlich model (R2 = 0.942–0.997) provides a better fit to the sorption isotherm data than the Langmuir model (R2 = 0.062–0.634), indicating that the sorption process takes place on the nonuniform surface of MPs. The MPs had a good sorption effect on OCPs when the solution/soil ratio was from 75:1 to 100:1. As the diameter of MPs increases, the sorption capacity decreases. These results provide support for further research on microplastic pollution in soil.
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•Sorption behaviors of OCPs on microplastics in soil suspension were studied.•The sorption amount of OCPs on MPs was detected directly by ultrasound extraction.•Sorption kinetics were best described by pseudo-second-order model.•The sorption isotherms of OCPs on PE are highly linear and conforms to Freundlich model.
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•The decay of airborne bacteria and fungi were observed in a constant temperature and humidity test chamber.•Microbial community in polluted PM2.5 had faster decay rates, more ...bacterial diversity and less fungal community.•The health risks of airborne microbe descend to a healthy level after 20 days without the input of peripheral environment.•Stable community structure and the volatile ones were related to the various metabolic survival strategies during different time.
Despite substantial research to profile the microbial characteristics in the atmosphere, the changing metabolism underpinning microbial successional dynamics remains ambiguous. Herein, we applied qPCR, high-throughput sequencing of the genes encoding 16S and ITS rRNA to render the bacterial/fungal dynamics of ambient PM2.5 filters maintained at constant conditions of temperature (20 ± 2 °C) and humidity (50 ± 5%). The incubation experiments which lasted for 50 days aim to simulate a metabolic process of microbe in two types PM2.5 (polluted and non-polluted). The results show that microbial community species in polluted PM2.5 had faster decay rates, more bacterial diversity and less fungal community compared to the non-polluted ones. For bacteria, the proportion of anaerobic species is higher than aerobic ones, and their performance of contain mobile elements, form-biofilms, and pathogenic risks declined rapidly as times went by. Whereas for fungi, saprotroph species occupied about 70% of the population, resulting in a specified peak of abundance due to the adequacy nutrients supplied by the apoptosis cells. Combining the classified microbial species, we found stable community structure and the volatile ones related to the various metabolic survival strategies during different time. Without the input of peripheral environment, the health risks of airborne microbe descend to a healthy level after 20 days, implying their biologic effectiveness was about 20 days no matter the air is polluted or not. This study provided new insights into the different metabolic survival of airborne microorganisms in ideal and stable conditions.
Rapid identification of clinical pathogens is the initial and essential step for antimicrobial therapy. Herein, we successfully developed a microfluidic device which combines high-throughput ...continuous-flow PCR and DNA hybridization for the detection of various bacterial pathogens. Universal primers were designed based on the conserved regions of bacterial 16S ribosomal DNA (16S rDNA), and specific probes were designed from a variable region of 16S rDNA within the amplicon sequences. In the chip operation, after the continuous flow PCR was achieved in the first microfluidic chip, the product was directly introduced into a hybridization chip integrated with microarray containing the immobilized DNA probes. The target-probe hybridization was completed within 1h at 55°C, and fluorescence signals were obtained as the readout. The presented device is simple, versatile and with less sample consumption compared with traditional instruments. It can perform high-throughput bacteria detections continuously in a single assay, which makes it a promising platform for clinical bacteria identifications.
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•An integrated microfluidic device was successfully developed, which is capable of continuous-flow high-throughput PCR and stationary DNA hybridization.•The mixture of five clinically significant bacterial species was used as PCR templates, and universal primers targeting the conserved region of bacterial 16S rDNA were used in the system.•The presented device showed potential application in point-of-care diagnostics.
Detecting atmospheric bioaerosols in a quantitative way is highly desirable for public health and safety. This work demonstrates that surface-enhanced Raman spectroscopy (SERS) is a simple and rapid ...analytical technique for the detection of atmospheric bioaerosols, on a Klarite substrate. For both simulated and ambient bioaerosols, this detection assay results in an increase in the enhancement factor of the Raman signal. We report a strong SERS signal generated by bioaerosols containing living
Escherichia coli
deposited on Klarite. Furthermore, we demonstrate that SERS mapping can be used to estimate the percentage of airborne, living
Escherichia coli
. Moreover, Klarite provides differently distinct SERS spectra at different bacterial growth phases, indicating its potential to identify changes occurring in the bacterial envelope. Finally, we applied SERS for the rapid detection of
Escherichia coli
in ambient bioaerosols without using time-consuming and laborious culture processes. Our results represent rapid, culture-free and label-free detection of airborne bacteria in the real-world environment.
We present a SERS-based Klarite interface for the rapid and culture-free detection and quantification of atmospheric bioaerosols in the real-world environment.
Exposure to indoor air pollution from solid fuel combustion is associated with lung diseases and cancer. This study investigated the cytotoxicity and molecular mechanisms of biomass ...combustion-derived particles in human pulmonary alveolar epithelial cells (HPAEpiC) using a platform that combines air-liquid interface (ALI) and dynamic culture (DC) systems.
HPAEpiC were cultured on the surface of polycarbonate (PC) membranes on the ALI-DC platform. The cells were sprayed with an aerosolized solution of biomass combustion soluble constituents (BCSCs) and simultaneously nourished with culture medium flowing beneath the permeable PC membranes. The ALI-DC method was compared with the traditional submerged culture approach. BCSC particle morphology and dosages deposited on the chip were determined for particle characterization. Flow cytometry, scanning electron microscopy, and transmission electron microscopy were used to investigate the apoptosis rate of HPAEpiC and changes in the cell ultrastructure induced by BCSCs. Additionally, the underlying apoptotic pathway was examined by determining the protein expression levels by western blotting.
Scanning electron microscope images demonstrated that the sample processing and delivering approach of the ALI-DC platform were suitable for pollutant exposure. Compared with the submerged culture method, a significant decline in cell viability and increase in apoptosis rate was observed after BCSC exposure on the ALI-DC platform, indicating that the ALI-DC platform is a more sensitive system for investigating cytotoxicity of indoor air pollutants in lung cells. The morphology and ultrastructure of the cells were damaged after exposure to BCSCs, and the p53 pathway was activated. The Bcl-2/Bax ratio was reduced, upregulating caspase-9 and caspase-3 expression and subsequently inducing apoptosis of HPAEpiC. The addition of N-acetyl cysteine antioxidant significantly alleviated the cytotoxicity induced by BCSCs.
A novel ALI-DC platform was developed to study the cytotoxicity of air pollutants on lung cells. Using the platform, we demonstrated that BCSCs could damage the mitochondria, produce reactive oxygen species, and activate p53 in HPAEpiC, ultimately inducing apoptosis.
Objectives
Lipoarabinomannan (LAM), an abundant cell wall glycolipid of mycobacteria including
Mycobacterium tuberculosis
(
Mtb
), is a promising TB diagnostic marker. The current commercially ...available urine LAM assays are not sufficiently sensitive, and more novel detection strategies are urgently needed to fill the current diagnostic gap.
Methods
A proteinase K-pretreated Concanavalin A (ConA)-based ELISA assay was developed. Diagnostic performance was assessed by several bacterial strains and clinical urine samples.
Results
The limit of detection (LoD) of the assay against ManLAM was 6 ng/ml. The assay reacted strongly to
Mtb
H37Rv and
M. bovis
BCG, intermediately to
M. smegmatis
mc
2
155, and weakly to four non-mycobacteria pathogens. This method could distinguish TB patients from healthy controls (HCs) and close contacts (CCs) in 71 urine samples treated with proteinase K, which increases urine LAM antibody reactiveness. In TB
+
HIV
+
and TB
+
HIV
−
patients, the sensitivity was 43.8 and 37.5%, respectively, while the specificity was 100.0%. The areas under ROC curves (AUCs) were 0.74 and 0.82, respectively.
Conclusion
This study implies that ConA can be paired with antibodies to detect LAM. Proteinase K treatment could effectively enhance the sensitivity by restoring the reactiveness of antibodies to LAM.
The SARS-CoV-2 infection that caused the COVID-19 pandemic quickly spread worldwide within two months. Rapid diagnosis of the disease and isolation of patients are effective ways to prevent and ...control the spread of COVID-19. Therefore, a sensitive immunofluorescent assay method was developed for rapid detection of special IgM and IgG of COVID-19 in human serum within 10 min. The recombinant nucleocapsid protein of 2019 novel coronavirus was used as capture antigen. Lanthanide, Eu(III) fluorescent microsphere, was used to qualitatively/semiquantitatively determine the solid phase immunochromatographic assay. A total of 28 clinical positive and 77 negative serum or plasma samples were included in the test. Based on the analysis of serum or plasma from COVID-19 patients and healthy people, the sensitivity and specificity of the immunochromatographic assay were calculated as 98.72% and 100% (IgG), and 98.68% and 93.10% (IgM), respectively. The results demonstrated that rapid immunoassay has high sensitivity and specificity and was useful for rapid serodiagnosis of COVID-19.
Nucleic acid detection, widely used in clinical diagnosis, biological analysis, and environmental monitoring, is of great significance for disease diagnosis and basic research. With the outbreak of ...COVID-19, the demand for fast and high-throughput nucleic acid detection from large numbers of samples has increased sharply. Automated nucleic acid detection systems can meet these needs, and also play important roles in disease screening and infectious disease prevention and control. In this review, we introduce and compare the current mainstream nucleic acid automatic detection instruments and equipment, then discuss the future demands of nucleic acid detection.
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