Traditional and molecular techniques for the study of emerging bacterial diseases: one laboratory's perspective

Validation of quantitative loop-mediated isothermal amplification assay using a fluorescent distance-based paper device for detection of Escherichia coli in urine

Uropathogenic Escherichia coli (UPEC) causes up to 90% of urinary tract infections (UTI) which is more prevalent among females than males. In urine, patients with symptomatic UTI usually have a high concentration of bacterial infection, ≥ 105 colony-forming units (CFU) per mL, in which the culture method is regularly the gold standard diagnosis. In this study, a simple and inexpensive distance-based paper device (dPAD) combined with the fluorescent closed tube LAMP assay was validated for simultaneously screening and semi-quantifying the infection level of E. coli in 440 urine samples of patients with UTI. The dPAD could measure the LAMP amplicons and semi-quantify the levels of E. coli infection in heavy (≥ 104 CFU/mL), light (≤ 103 CFU/mL) and no infection. The sensitivity and specificity had reliable performances, achieving as high as 100 and 92.7%, respectively. The one step LAMP assay could be performed within 3 h, which was 7.5 times faster than the culture method. To empower early UTI diagnosis and fast treatment, this inexpensive dPAD tool combined with the fluorescent closed tube LAMP assay is simple, reliably fast and practically portable for point-of-care settings, particularly in resource-limited areas, which can be set up in all levels of healthcare facilities.

The Underrated Gut Microbiota Helminths, Bacteriophages, Fungi, and Archaea

The microbiota inhabits the gastrointestinal tract, providing essential capacities to the host. The microbiota is a crucial factor in intestinal health and regulates intestinal physiology. However, microbiota disturbances, named dysbiosis, can disrupt intestinal homeostasis, leading to the development of diseases. Classically, the microbiota has been referred to as bacteria, though other organisms form this complex group, including viruses, archaea, and eukaryotes such as fungi and protozoa. This review aims to clarify the role of helminths, bacteriophages, fungi, and archaea in intestinal homeostasis and diseases, their interaction with bacteria, and their use as therapeutic targets in intestinal maladies.

Phages and Nanotechnology: New Insights against Multidrug-Resistant Bacteria

Bacterial infections are a major threat to the human healthcare system worldwide, as antibiotics are becoming less effective due to the emergence of multidrug-resistant strains. Therefore, there is a need to explore nontraditional antimicrobial alternatives to support rapid interventions and combat the spread of pathogenic bacteria. New nonantibiotic approaches are being developed, many of them at the interface of physics, nanotechnology, and microbiology. While physical factors (e.g., pressure, temperature, and ultraviolet light) are typically used in the sterilization process, nanoparticles and phages (bacterial viruses) are also applied to combat pathogenic bacteria. Particularly, phage-based therapies are rising due to the unparalleled specificity and high bactericidal activity of phages. Despite the success of phages mostly as compassionate use in clinical cases, some drawbacks need to be addressed, mainly related to their stability, bioavailability, and systemic administration. Combining phages with nanoparticles can improve their performance in vivo. Thus, the combination of nanotechnology and phages might provide tools for the rapid and accurate detection of bacteria in biological samples (diagnosis and typing), and the development of antimicrobials that combine the selectivity of phages with the efficacy of targeted therapy, such as photothermal ablation or photodynamic therapies. In this review, we aim to provide an overview of how phage-based nanotechnology represents a step forward in the fight against multidrug-resistant bacteria.

Genomic Characterization of Antimicrobial-Resistant Salmonella enterica in Duck, Chicken, and Pig Farms and Retail Markets in Eastern China

Antimicrobial-resistant Salmonella enterica poses a significant public health concern worldwide. However, the dissemination of Salmonella enterica among food animals in eastern China has not been fully addressed. Here, we demonstrated the antimicrobial resistance (AMR) patterns and the whole-genome characterization of 105 S. enterica isolates from 1,480 fecal samples and anal swabs collected from 22 different farms (chickens, ducks, and pigs) and two live animal markets located in Zhejiang and Fujian Provinces in eastern China in 2019. The prevalence of isolates in duck farms (19.17%, 23/120) was statistically significantly higher (P < 0.001) than that in chicken farms (6.61%, 37/523) and pig farms (3.50%, 7/200). Among these isolates, 75.26% (79/105) were multidrug resistant, with the highest rates of resistance to tetracycline (76.20%) and ampicillin (67.62%) and the lowest resistance rate to meropenem (0.00%). The serotypes were consistent with sequence types and were closely related to the sampling animal species and sites. S. enterica serotype Kentucky (20.95%, 22/105) was the most frequent serotype and harbored more AMR patterns and genes than others. Furthermore, IncFII(S) and IncHI2 were the most prevalent replicons. A total of 44 acquired AMR genes were found. Among those genes, aac(6')-Iaa, blaTEM-1B, floR, dfrA14, fosA7, mph(A), qnrS1, sul1, tet(A), and ARR-3 were the dominant AMR genes mediating the AMR toward aminoglycosides, β-lactams, phenicol, trimethoprim, fosfomycin, macrolide, quinolone, sulfonamides, tetracycline, and rifampin, respectively. The consistency of acquired AMR genes with AMR phenotypes for ampicillin, ceftiofur, ceftazidime, meropenem, sulfamethoxazole-trimethoprim, and tetracycline was >90%. Together, our study highlights the application of whole-genome sequencing to assess veterinary public health threats. IMPORTANCE Public health is a significant concern in China, and the foodborne pathogen Salmonella, which is spread via the animal-borne food chain, plays an important role in the overall disease burden in China annually. The development of advanced sequencing technologies has introduced a new way of understanding emerging pathogens. However, the routine surveillance application of this method in China remains in its infancy. Here, we applied a pool of all isolates from the prevalence data in Zhejiang and Fujian for whole-genome sequencing and combined these data with the cutting-edge bioinformatic analysis pipeline for one-step determination of the complete genetic makeup for all 105 genomes. The illustrated method could provide a cost-effective approach, without labor-intensive laboratory characterization, for predicting serotypes, genotypes, plasmid types, antimicrobial resistance genes, and virulence genes, and thus would provide essential knowledge for emerging pathogens. Our findings and perspectives are essential for delivering updated knowledge on foodborne pathogens in an understudied region in China.

Recent Progress and Challenges on the Microfluidic Assay of Pathogenic Bacteria Using Biosensor Technology

Microfluidic technology is one of the new technologies that has been able to take advantage of the specific properties of micro and nanoliters, and by reducing the costs and duration of tests, it has been widely used in research and treatment in biology and medicine. Different materials are often processed into miniaturized chips containing channels and chambers within the microscale range. This review (containing 117 references) demonstrates the significance and application of nanofluidic biosensing of various pathogenic bacteria. The microfluidic application devices integrated with bioreceptors and advanced nanomaterials, including hyperbranched nano-polymers, carbon-based nanomaterials, hydrogels, and noble metal, was also investigated. In the present review, microfluid methods for the sensitive and selective recognition of photogenic bacteria in various biological matrices are surveyed. Further, the advantages and limitations of recognition methods on the performance and efficiency of microfluidic-based biosensing of photogenic bacteria are critically investigated. Finally, the future perspectives, research opportunities, potential, and prospects on the diagnosis of disease related to pathogenic bacteria based on microfluidic analysis of photogenic bacteria are provided.

Biofilm Detection by a Fiber-Tip Ball Resonator Optical Fiber Sensor

Bacterial biofilms are one of the most important challenges that modern medicine faces due to the difficulties of diagnosis, antibiotic resistance, and protective mechanisms against aggressive environments. For these reasons, methods that ensure the inexpensive and rapid or real-time detection of biofilm formation on medical devices are needed. This study examines the possibilities of using optical- and fiber-based biosensors to detect and analyze early bacterial biofilms. In this study, the biofilm-forming model organism Pseudomonas aeruginosa was inoculated on the surface of the optical sensor and allowed to attach for 2 h. The biosensors were made by a fiber-tip ball resonator, fabricated through a CO2 laser splicer on a single-mode fiber, forming a weak reflective spectrum. An optical backscatter reflectometer was used to measure the refractive index detected by the sensors during different growth periods. The early biofilm concentration was determined by crystal violet (CV) binding assay; however, such a concentration was lower than the detection limit of this assay. This work presents a new approach of biofilm sensing in the early attachment stage with a low limit of detection up to 10−4 RIU (refractive index units) or 35 ± 20 × 103 CFU/mL (colony formed units).

Microfluidic devices for studying bacterial taxis, drug testing and biofilm formation

Some bacteria have coevolved to establish symbiotic or pathogenic relationships with plants, animals or humans. With human association, the bacteria can cause a variety of diseases. Thus, understanding bacterial phenotypes at the single-cell level is essential to develop beneficial applications. Traditional microbiological techniques have provided great knowledge about these organisms; however, they have also shown limitations, such as difficulties in culturing some bacteria, the heterogeneity of bacterial populations or difficulties in recreating some physical or biological conditions. Microfluidics is an emerging technique that complements current biological assays. Since microfluidics works with micrometric volumes, it allows fine-tuning control of the test conditions. Moreover, it allows the recruitment of three-dimensional (3D) conditions, in which several processes can be integrated and gradients can be generated, thus imitating physiological 3D environments. Here, we review some key microfluidic-based studies describing the effects of different microenvironmental conditions on bacterial response, biofilm formation and antimicrobial resistance. For this aim, we present different studies classified into six groups according to the design of the microfluidic device: (i) linear channels, (ii) mixing channels, (iii) multiple floors, (iv) porous devices, (v) topographic devices and (vi) droplet microfluidics. Hence, we highlight the potential and possibilities of using microfluidic-based technology to study bacterial phenotypes in comparison with traditional methodologies.

Biosensors and Point-of-Care Devices for Bacterial Detection: Rapid Diagnostics Informing Antibiotic Therapy

With an exponential rise in antimicrobial resistance and stagnant antibiotic development pipeline, there is, more than ever, a crucial need to optimize current infection therapy approaches. One of the most important stages in this process requires rapid and effective identification of pathogenic bacteria responsible for diseases. Current gold standard techniques of bacterial detection include culture methods, polymerase chain reactions, and immunoassays. However, their use is fraught with downsides with high turnaround time and low accuracy being the most prominent. This imposes great limitations on their eventual application as point-of-care devices. Over time, innovative detection techniques have been proposed and developed to curb these drawbacks. In this review, a systematic summary of a range of biosensing platforms is provided with a strong focus on technologies conferring high detection sensitivity and specificity. A thorough analysis is performed and the benefits and drawbacks of each type of biosensor are highlighted, the factors influencing their potential as point-of-care devices are discussed, and the authors' insights for their translation from proof-of-concept systems into commercial medical devices are provided.

Highly efficient enrichment and identification of pathogens using a herringbone microfluidic chip and by MALDI-TOF mass spectrometry

Bacterial infections cause considerable morbidity and expensive healthcare costs. The prescription of broad-spectrum antimicrobial drugs results in failure of treatment or overtreatment and exacerbates the spread of multidrug-resistant pathogens. There is an emergent demand for rapid and accurate methods to identify pathogens and conduct personalized therapy. Here, we develop a herringbone microfluidic chip integrated with vancomycin modified magnetic beads (herringbone-VMB microchip) to enrich pathogens. The enriched pathogens are identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. The herringbone-VMB microchip applies passive mixing of bacterial samples by generating microvortices, which significantly enhances the interaction between bacteria and vancomycin modified magnetic beads and leads to more efficient enrichment compared to in-tube extraction. Four common pathogens in urinary tract infections are utilized to validate the method, and the capture efficiency of the bacteria from urine is up to 90%. The whole procedure takes 1.5 hours from enrichment to identification. This method shows potential in shortening the turnaround time in the clinical diagnosis of bacterial infections.

Finding a Balance in the Vaginal Microbiome: How Do We Treat and Prevent the Occurrence of Bacterial Vaginosis?

Bacterial vaginosis (BV) has been reported in one-third of women worldwide at different life stages, due to the complex balance in the ecology of the vaginal microbiota. It is a common cause of abnormal vaginal discharge and is associated with other health issues. Since the first description of anaerobic microbes associated with BV like Gardnerella vaginalis in the 1950s, researchers have stepped up the game by incorporating advanced molecular tools to monitor and evaluate the extent of dysbiosis within the vaginal microbiome, particularly on how specific microbial population changes compared to a healthy state. Moreover, treatment failure and BV recurrence rate remain high despite the standard antibiotic treatment. Consequently, researchers have been probing into alternative or adjunct treatments, including probiotics or even vaginal microbiota transplants, to ensure successful treatment outcomes and reduce the colonization by pathogenic microbes of the female reproductive tract. The current review summarizes the latest findings in probiotics use for BV and explores the potential of vaginal microbiota transplants in restoring vaginal health.

Metagenomic analysis of individually analyzed ticks from Eastern Europe demonstrates regional and sex-dependent differences in the microbiota of Ixodes ricinus

Understanding the microbial ecology of disease vectors may be useful for development of novel strategies aimed at preventing transmission of vector-borne pathogens. Although Ixodes ricinus is one of the most important tick vectors, the microbiota of this tick has been examined for only limited parts of the globe. To date, the microbiota of I. ricinus ticks collected from Eastern Europe has not been defined. The objective of this study was to compare microbiota of I. ricinus ticks within (males vs. females) and between collection sites that represented three administrative regions of Ukraine, Dnipropetrovs'k (D), Kharkiv (K), and Poltava (P). A total of 89 questing I. ricinus adults were collected from region D (number of ticks, n = 29; 14 males and 15 females), region K (n = 30; 15 males and 15 females) and region P (n = 30; 15 males and 15 females). Each tick was subjected to metagenomic analysis by targeting the V6 region of 16S rRNA gene through the Illumina 4000 Hiseq sequencing. The alpha diversity analysis demonstrated that, regardless of tick sex, patterns of bacterial diversity in ticks from regions K and P were similar, whereas the microbiota of region D ticks was quite distinct. A number of inter-regional differences were detected by most beta diversity metrics for both males and females. The inter-regional variations were also supported by the principal coordinate analysis based on the unweighted UniFrac metrics with three region-specific clusters of female ticks and one distinct cluster of region D males. Lastly, numerous region- and sex-specific differences were also identified in the relative abundance of various bacterial taxa. Collectively, the present findings demonstrate that the microbiota of the I. ricinus tick can exhibit a high degree of variation between tick sexes and geographical regions.

Development of a fluorescent distance-based paper device using loop-mediated isothermal amplification to detect Escherichia coli in urine

The highly sensitive and selective determination of Escherichia coli (E. coli) in urine was achieved using a SYBR™ safe loop-mediated isothermal amplification (LAMP) method with a distance-based paper device. New primers set specific to multi-copy the 16s rRNA gene of E. coli were designed and used in this study. The detection sensitivity of these primers was higher than in related work and they could be incorporated with a low-cost paper-based device to quantify E. coli in urine at a concentration lower than 101 CFU mL-1. Regarding standard artificial urine, a linear range of a 10-fold dilution of E. coli concentration (105-100 CFU mL-1) with an R-square value (R2) = 0.9823 was observed directly using a fluorescent migratory distance of the 4 μL reaction mixture in the detection zone under blue light without the need for postreaction staining process. Based on the device, E. coli infection could be significantly categorized into 3 groups; none, light, and heavy levels, which is beneficial for UTI diagnosis. Hence, this paper-based device is suitable for use with the SYBR™ Safe-LAMP assay to semi-quantify E. coli, especially in resource-limited settings due to advantages of low cost, simple fabrication and operation, and no requirement for sophisticated instruments, as well as its disposability and portability.

Microbial Communities of Meat and Meat Products: An Exploratory Analysis of the Product Quality and Safety at Selected Enterprises in South Africa

Consumption of food that is contaminated by microorganisms, chemicals, and toxins may lead to significant morbidity and mortality, which has negative socioeconomic and public health implications. Monitoring and surveillance of microbial diversity along the food value chain is a key component for hazard identification and evaluation of potential pathogen risks from farm to the consumer. The aim of this study was to determine the microbial diversity in meat and meat products from different enterprises and meat types in South Africa. Samples (n = 2017) were analyzed for Yersinia enterocolitica, Salmonella species, Listeria monocytogenes, Campylobacter jejuni, Campylobacter coli, Staphylococcus aureus, Clostridium perfringens, Bacillus cereus, and Clostridium botulinum using culture-based methods. PCR was used for confirmation of selected pathogens. Of the 2017 samples analyzed, microbial ecology was assessed for selected subsamples where next generation sequencing had been conducted, followed by the application of computational methods to reconstruct individual genomes from the respective sample (metagenomics). With the exception of Clostridium botulinum, selective culture-dependent methods revealed that samples were contaminated with at least one of the tested foodborne pathogens. The data from metagenomics analysis revealed the presence of diverse bacteria, viruses, and fungi. The analyses provide evidence of diverse and highly variable microbial communities in products of animal origin, which is important for food safety, food labeling, biosecurity, and shelf life limiting spoilage by microorganisms.

Characterization of Microbial Communities in Ixodes persulcatus (Ixodida: Ixodidae), a Veterinary and Medical Important Tick Species in Northeastern China

The importance of ticks in veterinary and medical science has received much attention. The dominant tick species in northeastern China, Ixodes persulcatus tick can transmit various pathogens to humans and animals and there are some studies on the microbiome composition of this tick. Our study characterized the bacterial communities in I. persulcatus by 16S amplicon pyrosequencing and described the differences of microorganisms in male and female tick and assessed the variation of microorganisms in the development stages in northeastern China. We mainly found the following bacteria genera: Pseudomonas (Pseudomonadales: Pseudomonadaceae), Citrobacter (Enterobacteriales: Enterobacteriaceae), and Rickettsia (Rickettsiales: Rickettsiaceae). Rickettsia is common and harmful pathogen transmitted by ticks. Meanwhile, we found there were differences between male and female tick of microbiomes, and the diversity of microbiome increased from engorged female ticks to eggs, but decreased when the eggs were molting into larvae. Our data showed that male ticks exhibited greater microbial diversity than female I. persulcatus tick and larvae presented with a different bacterial community compared to engorged female tick and hatched eggs. These findings may be useful for further understanding the interaction between I. persulcatus and microbiome biology.

High-Content Screening, a Reliable System for Coxiella burnetii Isolation from Clinical Samples

Q fever, caused by Coxiella burnetii, is a worldwide zoonotic disease that may cause severe forms in humans and requires a specific and prolonged antibiotic treatment. Although current serological and molecular detection tools allow a reliable diagnosis of the disease, culture of C. burnetii strains is mandatory to assess their susceptibility to antibiotics and sequence their genome in order to optimize patient management and epidemiological studies. However, cultivating this fastidious microorganism is difficult and restricted to reference centers, as it requires biosafety level 3 laboratories and relies on cell culture performed by experienced technicians. In addition, the culture yield is low, which results in a small number of isolates being available. In this work, we developed a novel high-content screening (HCS) isolation strategy based on optimized high-throughput cell culture and automated microscopic detection of infected cells with specifically designed algorithms targeting cytopathic effects. This method was more efficient than the shell vial assay, at the level of time dependency, when applied to both frozen specimens (7 isolates recovered by HCS only, sensitivity 91% versus 78% for shell vial) and fresh samples (1 additional isolate using HCS, sensitivity 7% versus 5% for shell vial), for which most strains were recovered more rapidly with the new technique. In addition, detecting positive cultures by an automated microscope reduced the need for expertise and saved 24% of technician working time. Application of HCS to antibiotic susceptibility testing of 12 strains demonstrated that it was as efficient as the standard procedure that combines shell vial culture and quantitative PCR.

Coculture at the crossroads of the new microbiology techniques for the isolation of strict intracellular bacteria

Coculture played a major role in clinical microbiology by elucidating strict intracellular bacteria era. Since some of these bacteria are human pathogens, in-depth studies at the strain level are necessary to better understand their pathologies and treatment. Over the last decades, culture-independent tools have taken over the diagnostic procedure at the expense of coculture. These tools, although proven to be rapid and efficient, cannot overcome the need to culture the bacteria, as strain isolation remains a key factor to understanding its epidemiology, virulence and antibiotic susceptibility testing. Moreover, strain availability allows the development of molecular and serological tools, and remains crucial for taxonomy. This review revisits the current status of culture, its advantages, drawbacks and future needs.

A review of methods for the detection of pathogenic microorganisms

The testing and rapid detection of pathogenic organisms is a crucial protocol in the prevention and identification of crises related to health, safety and wellbeing. Pathogen detection has become one of the most challenging aspects in the food and water industries, because of the rapid spread of waterborne and foodborne diseases in the community and at significant costs. With the prospect of inevitable population growth, and an influx of tourism to certain water bodies testing will become a requirement to control and prevent possible outbreaks of potentially fatal illnesses. The legislation is already particularly rigorous in the food industry, where failure to detect pathogenic materials represents a catastrophic event, particularly for the elderly, very young or immune-compromised population types. In spite of the need and requirement for rapid analytical testing, conventional and standard bacterial detection assays may take up to seven days to yield a result. Given the advent of new technologies, biosensors, chemical knowledge and miniaturisation of instrumentation this timescale is not acceptable. This review presents an opportunity to fill a knowledge gap for an extremely important research area; discussing the main techniques, biology, chemistry, miniaturisation, sensing and the emerging state-of-the-art research and developments for detection of pathogens in food, water, blood and faecal samples.

Novel neural network application for bacterial colony classification

BACKGROUND

Bacterial colony morphology is the first step of classifying the bacterial species before sending them to subsequent identification process with devices, such as VITEK 2 automated system and mass spectrometry microbial identification system. It is essential as a pre-screening process because it can greatly reduce the scope of possible bacterial species and will make the subsequent identification more specific and increase work efficiency in clinical bacteriology. But this work needs adequate clinical laboratory expertise of bacterial colony morphology, which is especially difficult for beginners to handle properly. This study presents automatic programs for bacterial colony classification task, by applying the deep convolutional neural networks (CNN), which has a widespread use of digital imaging data analysis in hospitals. The most common 18 bacterial colony classes from Peking University First Hospital were used to train this framework, and other images out of these training dataset were utilized to test the performance of this classifier.

RESULTS

The feasibility of this framework was verified by the comparison between predicted result and standard bacterial category. The classification accuracy of all 18 bacteria can reach 73%, and the accuracy and specificity of each kind of bacteria can reach as high as 90%.

CONCLUSIONS

The supervised neural networks we use can have more promising classification characteristics for bacterial colony pre-screening process, and the unsupervised network should have more advantages in revealing novel characteristics from pictures, which can provide some practical indications to our clinical staffs.

Detecting Biothreat Agents: From Current Diagnostics to Developing Sensor Technologies

Although a fundamental understanding of the pathogenicity of most biothreat agents has been elucidated and available treatments have increased substantially over the past decades, they still represent a significant public health threat in this age of (bio)terrorism, indiscriminate warfare, pollution, climate change, unchecked population growth, and globalization. The key step to almost all prevention, protection, prophylaxis, post-exposure treatment, and mitigation of any bioagent is early detection. Here, we review available methods for detecting bioagents including pathogenic bacteria and viruses along with their toxins. An introduction placing this subject in the historical context of previous naturally occurring outbreaks and efforts to weaponize selected agents is first provided along with definitions and relevant considerations. An overview of the detection technologies that find use in this endeavor along with how they provide data or transduce signal within a sensing configuration follows. Current "gold" standards for biothreat detection/diagnostics along with a listing of relevant FDA approved in vitro diagnostic devices is then discussed to provide an overview of the current state of the art. Given the 2014 outbreak of Ebola virus in Western Africa and the recent 2016 spread of Zika virus in the Americas, discussion of what constitutes a public health emergency and how new in vitro diagnostic devices are authorized for emergency use in the U.S. are also included. The majority of the Review is then subdivided around the sensing of bacterial, viral, and toxin biothreats with each including an overview of the major agents in that class, a detailed cross-section of different sensing methods in development based on assay format or analytical technique, and some discussion of related microfluidic lab-on-a-chip/point-of-care devices. Finally, an outlook is given on how this field will develop from the perspective of the biosensing technology itself and the new emerging threats they may face.

Tick Microbiome Characterization by Next-Generation 16S rRNA Amplicon Sequencing

In recent decades, vector-borne diseases have re-emerged and expanded at alarming rates, causing considerable morbidity and mortality worldwide. Effective and widely available vaccines are lacking for a majority of these diseases, necessitating the development of novel disease mitigation strategies. To this end, a promising avenue of disease control involves targeting the vector microbiome, the community of microbes inhabiting the vector. The vector microbiome plays a pivotal role in pathogen dynamics, and manipulations of the microbiome have led to reduced vector abundance or pathogen transmission for a handful of vector-borne diseases. However, translating these findings into disease control applications requires a thorough understanding of vector microbial ecology, historically limited by insufficient technology in this field. The advent of next-generation sequencing approaches has enabled rapid, highly parallel sequencing of diverse microbial communities. Targeting the highly-conserved 16S rRNA gene has facilitated characterizations of microbes present within vectors under varying ecological and experimental conditions. This technique involves amplification of the 16S rRNA gene, sample barcoding via PCR, loading samples onto a flow cell for sequencing, and bioinformatics approaches to match sequence data with phylogenetic information. Species or genus-level identification for a high number of replicates can typically be achieved through this approach, thus circumventing challenges of low detection, resolution, and output from traditional culturing, microscopy, or histological staining techniques. Therefore, this method is well-suited for characterizing vector microbes under diverse conditions but cannot currently provide information on microbial function, location within the vector, or response to antibiotic treatment. Overall, 16S next-generation sequencing is a powerful technique for better understanding the identity and role of vector microbes in disease dynamics.

Surface-Enhanced Raman Scattering (SERS) in Microbiology: Illumination and Enhancement of the Microbial World

The microbial world forms a huge family of organisms that exhibit the greatest phylogenetic diversity on Earth and thus colonize virtually our entire planet. Due to this diversity and subsequent complex interactions, the vast majority of microorganisms are involved in innumerable natural bioprocesses and contribute an absolutely vital role toward the maintenance of life on Earth, whilst a small minority cause various infectious diseases. The ever-increasing demand for environmental monitoring, sustainable ecosystems, food security, and improved healthcare systems drives the continuous search for inexpensive but reproducible, automated and portable techniques for detection of microbial isolates and understanding their interactions for clinical, environmental, and industrial applications and benefits. Surface-enhanced Raman scattering (SERS) is attracting significant attention for the accurate identification, discrimination and characterization and functional assessment of microbial cells at the single cell level. In this review, we briefly discuss the technological advances in Raman and Fourier transform infrared (FT-IR) instrumentation and their application for the analysis of clinically and industrially relevant microorganisms, biofilms, and biological warfare agents. In addition, we summarize the current trends and future prospects of integrating Raman/SERS-isotopic labeling and cell sorting technologies in parallel, to link genotype-to-phenotype in order to define community function of unculturable microbial cells in mixed microbial communities which possess admirable traits such as detoxification of pollutants and recycling of essential metals.

The Inoculation Method Could Impact the Outcome of Microbiological Experiments

For the past 150 years, bacteria have been investigated primarily in liquid batch cultures. Contrary to most expectations, these cultures are not homogeneous mixtures of single-cell bacteria, because free-floating bacterial aggregates eventually develop in most liquid batch cultures. These aggregates share characteristics with biofilms, such as increased antibiotic tolerance. We investigated how aggregates develop and what influences this development in liquid batch cultures of Pseudomonas aeruginosa We focused on how the method of inoculation affected aggregation by assessing aggregate frequency and size using confocal laser scanning microscopy. Several traditional methods of initiating an overnight bacterial culture, i.e., inoculation directly from frozen cultures, inoculation using agar-grown cells, or inoculation using cells grown in liquid cultures, were investigated. We discovered a direct link between the inoculation method and the size and frequency of biofilm aggregates in liquid batch cultures, with inoculation directly from a plate resulting in the most numerous and largest aggregates. These large aggregates had an overall impact on the cultures' subsequent tolerance toward tobramycin, indicating that the inoculation method has a profound impact on antibiotic tolerance. We also observed a mechanism whereby preformed aggregates recruited single cells from the surrounding culture in a "snowball effect," building up aggregated biomass in the culture. This recruitment was found to rely heavily on the exopolysaccharide Psl. Additionally, we found that both Escherichia coli and Staphylococcus aureus produced aggregates in liquid batch cultures. Our results stress the importance of inoculation consistency throughout experiments and the substantial impact aggregate development in liquid batch cultures may have on the outcomes of microbiological experiments.IMPORTANCE Pure liquid cultures are fundamental to the field of microbiological research. These cultures are normally thought of as homogeneous mixtures of single-cell bacteria; the present study shows that this is not always true. Bacteria may aggregate in these liquid cultures. The aggregation can be induced by the method chosen for inoculation. The presence of aggregates can significantly change the outcomes of experiments by altering the phenotype of the cultures. The study found a mechanism whereby preformed aggregates are able to recruit surrounding single cells in a form of snowball effect, creating more and larger aggregates in the cultures. Once formed, these aggregates are hard to remove. Aggregates in liquid cultures may be an immense unseen challenge for microbiologists.

Microbial communities associated with the co-metabolism of free cyanide and thiocyanate under alkaline conditions

This study focused on the identification of free cyanide (CDO) and thiocyanate (TDO) degrading microbial communities using a culture-dependent and independent approach. Culturable microbial species were isolated from the CDOs (n = 13) and TDOs (n = 18). The CDOs were largely dominated by Bacillus sp. while the TDOs were dominated by Bacillus sp., Klebsiella oxytoca, Providencia sp. and Pseudomonas sp. However, 16S rRNA amplicon gene-sequencing revealed the complexity and diversity of the microbial communities in contrast to the organisms that were detected using culture-dependent technique. Overall, the organisms were mainly dominated by Myroides odoratimimus and Proteus sp. at 37.82 and 30.5% for CDOs, and 35.26 and 17.58% for TDOs, respectively. The co-culturing of the CDOs and TDOs resulted in biochemical changes of key metabolic enzymes, and this resulted in the complete degradation of CN- and SCN- simultaneously; a phenomenon which has not been witnessed, especially under alkaline conditions. Current ongoing studies are focused on the application of these organisms for the biodegradation of CN- and SCN- in a continuous system, under changing operational parameters, to assess their effectiveness in the biodegradation of CN- and SCN-.

Using typing techniques in a specific outbreak: the ethical reflection of public health professionals

Typing techniques are laboratory methods used in outbreak management to investigate the degree to which microbes found within an outbreak are related. Knowledge about relational patterns between microbes benefits outbreak management, but inevitably also tells us something about the relational patterns of the people hosting them. Since the technique is often used without explicit consent of all individuals involved, this may raise ethical questions. The aim of this study was to unravel the complex ethical deliberation of professionals over the use of such techniques. We organised group discussions (n = 3) with Dutch outbreak managers (n = 23). The topic list was based on previously identified ethical issues and discussions were analysed for recurrent themes. We found that outbreak managers first and foremost reflect on the balance of individual harm with public health benefit. This key question was approached by way of discussing four more specific ethical themes: (1) justification of governmental intervention, (2) responsibility to prevent infections, (3) scientific uncertainty and (4) legal consequences. The themes found in this study, rephrased into accessible questions, represent the shared ethical understanding of professionals and can help to articulate the ethical dimensions of using molecular science in response to infectious disease outbreaks.

Application of Routine Diagnostic Procedure, VITEK 2 Compact, MALDI-TOF MS, and PCR Assays in Identification Procedure of Bacterial Strain with Ambiguous Phenotype

In diagnostic microbiology as well as in microbiological research, the identification of a microorganism is a crucial and decisive stage. A broad choice of methods is available, based on both phenotypic and molecular properties of microbes. The aim of this study was to compare the application of phenotypic and molecular tools in bacterial identification on the example of Gram-negative intestine rod with an ambiguous phenotype. Different methods of identification procedure, which based on various properties of bacteria, were applied, e.g., microscopic observation of single-bacterial cells, macroscopic observation of bacterial colonies morphology, the automated system of microorganism identification (biochemical tests), the mass spectrometry method (analysis of bacterial proteome), and genetic analysis with PCR reactions. The obtained results revealed discrepancies in the identification of the tested bacterial strain with an atypical phenotype: mucous morphology of colonies, not characteristic for either E. coli and Citrobacter spp., mass spectrometry analysis of proteome initially assigned the tested strain to Citrobacter genus (C. freundii) and biochemical profiles pointed to Escherichia coli. A decisive method in the current study was genetic analysis with PCR reactions which identified conserved genetic sequences highly specific to E. coli species in the genome of the tested strain.

Emerging bacterial pathogens: the past and beyond

Since the 1950s, medical communities have been facing with emerging and reemerging infectious diseases, and emerging pathogens are now considered to be a major microbiologic public health threat. In this review, we focus on bacterial emerging diseases and explore factors involved in their emergence as well as future challenges. We identified 26 major emerging and reemerging infectious diseases of bacterial origin; most of them originated either from an animal and are considered to be zoonoses or from water sources. Major contributing factors in the emergence of these bacterial infections are: (1) development of new diagnostic tools, such as improvements in culture methods, development of molecular techniques and implementation of mass spectrometry in microbiology; (2) increase in human exposure to bacterial pathogens as a result of sociodemographic and environmental changes; and (3) emergence of more virulent bacterial strains and opportunistic infections, especially affecting immunocompromised populations. A precise definition of their implications in human disease is challenging and requires the comprehensive integration of microbiological, clinical and epidemiologic aspects as well as the use of experimental models. It is now urgent to allocate financial resources to gather international data to provide a better understanding of the clinical relevance of these waterborne and zoonotic emerging diseases.

A novel molecular microbiologic technique for the rapid diagnosis of microbial invasion of the amniotic cavity and intra-amniotic infection in preterm labor with intact membranes

PROBLEM

The diagnosis of microbial invasion of the amniotic cavity (MIAC) has been traditionally performed using traditional cultivation techniques, which require growth of microorganisms in the laboratory. Shortcomings of culture methods include the time required (days) for identification of microorganisms, and that many microbes involved in the genesis of human diseases are difficult to culture. A novel technique combines broad-range real-time polymerase chain reaction with electrospray ionization time-of-flight mass spectrometry (PCR/ESI-MS) to identify and quantify genomic material from bacteria and viruses.

METHOD OF STUDY

AF samples obtained by transabdominal amniocentesis from 142 women with preterm labor and intact membranes (PTL) were analyzed using cultivation techniques (aerobic, anaerobic, and genital mycoplasmas) as well as PCR/ESI-MS. The prevalence and relative magnitude of intra-amniotic inflammation [AF interleukin 6 (IL-6) concentration ≥ 2.6 ng/mL], acute histologic chorioamnionitis, spontaneous preterm delivery, and perinatal mortality were examined.

RESULTS

(i) The prevalence of MIAC in patients with PTL was 7% using standard cultivation techniques and 12% using PCR/ESI-MS; (ii) seven of ten patients with positive AF culture also had positive PCR/ESI-MS [≥17 genome equivalents per PCR reaction well (GE/well)]; (iii) patients with positive PCR/ESI-MS (≥17 GE/well) and negative AF cultures had significantly higher rates of intra-amniotic inflammation and acute histologic chorioamnionitis, a shorter interval to delivery [median (interquartile range-IQR)], and offspring at higher risk of perinatal mortality, than women with both tests negative [90% (9/10) versus 32% (39/122) OR: 5.6; 95% CI: 1.4-22; (P < 0.001); 70% (7/10) versus 35% (39/112); (P = 0.04); 1 (IQR: <1-2) days versus 25 (IQR: 5-51) days; (P = 0.002), respectively]; (iv) there were no significant differences in these outcomes between patients with positive PCR/ESI-MS (≥17 GE/well) who had negative AF cultures and those with positive AF cultures; and (v) PCR/ESI-MS detected genomic material from viruses in two patients (1.4%).

CONCLUSION

(i) Rapid diagnosis of intra-amniotic infection is possible using PCR/ESI-MS; (ii) the combined use of biomarkers of inflammation and PCR/ESI-MS allows for the identification of specific bacteria and viruses in women with preterm labor and intra-amniotic infection; and (iii) this approach may allow for administration of timely and specific interventions to reduce morbidity attributed to infection-induced preterm birth.

Technical Advances in Veterinary Diagnostic Microbiology

Forming a significant part of biomass on earth, microorganisms are renowned for their abundance and diversity. From submicroscopic infectious particles (viruses), small unicellular cells (bacteria and yeasts) to multinucleate and multicellular organisms (filamentous fungi, protozoa, and helminths), microorganisms have found their way into virtually every environmental niche, and show little restrain in making their presence felt. While a majority of microorganisms are free-living and involved in the degradation of plant debris and other organic materials, others lead a symbiotic, mutually beneficial life within their hosts. In addition, some microorganisms have the capacity to take advantage of temporary weaknesses in animal and human hosts, causing notable morbidity and mortality. Because clinical manifestations in animals and humans resulting from infections with various microorganisms are often nonspecific (e.g., general malaise and fever), it is necessary to apply laboratory diagnostic means to identify the culprit organisms for treatment and prevention purposes.

Comparison of real-time quantitative PCR and culture for the diagnosis of emerging Rickettsioses

Background

Isolation of Rickettsia species from skin biopsies may be replaced by PCR. We evaluated culture sensitivity compared to PCR based on sampling delay and previous antibiotic treatment.

Methodology/Principal Findings

Skin biopsies and ticks from patients with suspected Rickettsia infection were screened for Rickettsia spp. using qPCR, and positive results were amplified and sequenced for the gltA and ompA genes. Immunofluorescence for spotted fever group rickettsial antigens was done for 79 patients. All skin biopsies and only ticks that tested positive using qPCR were cultured in human embryonic lung (HEL) fibroblasts using the centrifugation-shell vial technique. Patients and ticks were classified as definitely having rickettsioses if there was direct evidence of infection with a Rickettsia sp. using culture or molecular assays or in patients if serology was positive. Data on previous antibiotic treatments were obtained for patients with rickettsiosis. Rickettsia spp. infection was diagnosed in 47 out of 145 patients (32%), 41 by PCR and 12 by culture, whereas 3 isolates were obtained from PCR negative biopsies. For 3 of the patients serology was positive although PCR and culture were negative. Rickettsia africae was the most common detected species (n = 25, [17.2%]) and isolated bacterium (n = 5, [3.4%]). The probability of isolating Rickettsia spp. was 12 times higher in untreated patients and 5.4 times higher in patients from our hometown. Rickettsia spp. was amplified in 24 out of 95 ticks (25%) and we isolated 7 R. slovaca and 1 R. raoultii from Dermacentor marginatus.

Conclusions/Significance

We found a positive correlation between the bacteria copies and the isolation success in skin biopsies and ticks. Culture remains critical for strain analysis but is less sensitive than serology and PCR for the diagnosis of a Rickettsia infection.

Diagnosis of Rickettsia infection would benefit by use of the more rapid and sensitive method of quantitative real-time PCR than the time-intensive and less sensitive method of culturing Rickettsia species from skin biopsies. We evaluated culture sensitivity compared to PCR according to sampling delay and previous antibiotic treatment. We found that skin biopsies can be positive even when molecular tests were negative, and a negative result using molecular assays did not exclude the diagnosis of Rickettsia spp. infection. Rickettsia africae was the most common species in skin biopsies and R. slovaca was most common in ticks. We found a positive correlation between the number of bacteria copies and the isolation success in skin biopsies and ticks. The probability of isolating Rickettsia spp. was higher in untreated patients and in patients from our hometown. To increase the sensitivity of culture, skin biopsies should be sampled before treatment early in the course of the disease and should be inoculated as soon as possible.

Dynamics of the Vaginal Ecosystem—Hormonal Influences

The vagina is a dynamic and finely tuned ecosystem in which homeostasis depends on mutually beneficial interactions between a human female and her resident microorganisms, an ecosystem that can be thrown off balance by a wide variety of both intrinsic and extrinsic factors. Although a functional equilibrium provides stability to the ecosystem considered crucial to maintaining vaginal health, “normal flora” is a concept currently being redefined. New methodologies enable molecular analyses of the vaginal microbiota which have widened the definition of “normal” from a single specific microbiological profile to a range of functional microbial equilibria dependent upon pertinent host and microbial factors. One of the strongest influences on the vaginal microbiota is the hormonal changes that define the reproductive phases of a woman's life. The vaginal environment is particularly responsive to estrogen, a hormone that creates distinctive changes in the vaginal microbiota. This review summarizes the components of a healthy vaginal ecosystem during the reproductive years, including the characteristics of a healthy equilibrium and factors that can disturb a functional balance. It also summarizes what is known about the vaginal microbiota in childhood and after menopause. Healthful ecosystems at any stage of a female's reproductive life will be characterized by a microbiota that both maintains physiological function and though changeable, adapts to normal perturbation without succumbing to disease.

Characterization of Clostridium species utilizing liquid chromatography/mass spectrometry of intact proteins

A method for biomarker candidate discovery and strain level pathogen characterization using liquid chromatography/mass spectrometry (LC/MS) with electrospray ionization is described. This method was applied to two pathogenic Clostridium species: C. difficile and C. perfringens. Seven marker proteins per species (fourteen total) were successfully implemented to speciate unknowns during a blind study and could enhance serological and genetic approaches by serving as new targets for detection. Two sets of C. perfringens isolates that were 100% similar by pulsed-field gel electrophoresis (PFGE) were distinguished using LC/MS, demonstrating the high specificity of this approach. The use of LC/MS is less labor intensive than PFGE, affords greater specificity than real-time PCR, and requires no primers or antibodies.

Advances in the microbiological diagnosis of sepsis

Accurate diagnostic tests are essential for the correct identification of etiologic agents causing sepsis. Conventional microbiology cultures are time consuming and may even yield negative results in many cases of septic shock. In this manner, molecular-based technologies are emerging as promising tests for use into routine clinical laboratories. In this review, we discuss current available molecular methods for bacteremia diagnosis in adult and pediatric patients with suspected or confirmed sepsis. Results of studies using polymerase chain reaction, real-time polymerase chain reaction, and complementary DNA/oligonucleotide microarrays are described and discussed into the current scenario. These new methodologies are able to detect even small amounts of bacterial DNA directly from blood specimens and show increased sensitivity and specificity for detecting many infectious agents associated with sepsis. Despite some limitations presented by nucleic acid-based techniques, these genotypic tests can be useful along with traditional microbiology diagnostics.

Liquid chromatography/mass spectrometry characterization of Escherichia coli and Shigella species

Liquid chromatography/quadrupole time of flight mass spectrometry (LC/QTOF MS) utilizing electrospray ionization was employed to monitor protein expression in Escherichia coli and Shigella organisms. Comparison with MALDI/TOF-MS revealed more proteins, particularly above 15 kDa. A combination of automated charge state deconvolution, spectral mirroring, and spectral subtraction was used to reveal subtle differences in the LC/MS data. Reproducible intact protein biomarker candidates were discovered based on their unique mass, retention time, and relative intensity. These marker candidates were implemented to differentiate closely related strain types, (e.g., two distinct isolates of E. coli O157:H7) and to correctly identify unknown pathogens. This LC/MS approach is less labor-intensive than pulsed-field gel electrophoresis, affords greater specificity than real-time PCR, and requires no primers or antibodies. Additionally, this approach would be beneficial during outbreaks of foodborne disease or bioterrorism investigations by complementing methods typically used in diagnostic microbiology laboratories.

Validation of 16S rDNA sequencing in microdissected bowel biopsies from Crohn's disease patients to assess bacterial flora diversity

The bowel flora is implicated in Crohn's disease (CD) pathogenesis but its precise role is still unclear. Several non-mutually exclusive hypotheses have been proposed: an unidentified persistent pathogen; excessive bacterial translocation; an immune system abnormality in response to normal bacteria; or a breakdown in the balance between protective and harmful bacteria. These hypotheses can be tested by identifying bacteria in specific microscopic bowel structures or lesions. The present paper describes a novel technique to assess bacterial flora diversity in bowel biopsies, by combining laser capture microdissection with broad-range 16S rDNA sequencing. Fifty-four samples comprising histologically normal and pathological mucosa, MALT, ulcers, submucosal lymphangiectasias, epithelioid granulomas, and lymph nodes were microdissected out of 30 bowel biopsies from five CD patients. Bacterial 16S rDNA was successfully amplified by PCR in all samples, and PCR products from 15 samples were selected for cloning and sequence analysis. A total of 729 bacterial DNA sequences were analysed, which could be attributed to six different phyla (Proteobacteria, Firmicutes, Bacteroidetes, Actinobacteria, Fusobacteria, and Planctomycetes). DNA from typical bowel bacteria (Enterobacteriaceae, Clostridiales, Bacteroidetes, Fusobacteria) was detected in all microdissected areas. It was thus convincingly demonstrated that 16S rDNA sequencing can be combined with microdissection to study the bowel flora. However, no specific persistent pathogen causal for CD was identified. The results suggest that Enterobacteriaceae may initiate or colonize ulcers in CD. Translocation of bacteria through established mucosal lesions or as a result of increased permeability may be involved in the evolution towards chronic inflammation and in the establishment of persistent lesions. Further study is needed to confirm these preliminary findings.

Use of shell-vial cell culture assay for isolation of bacteria from clinical specimens: 13 years of experience

The shell-vial culture assay is performed routinely in our laboratory. Recently we revisited our experience of using the shell-vial culture assay for the isolation of microorganisms from various clinical samples. Over a 13-year period, we have isolated 580 bacterial strains (5%) from 11,083 clinical samples tested. Over the same period, 285 isolates of rickettsiae, bartonellae, or Coxiella burnetii were cultured from a total of 7,102 samples tested. These isolates include 55 Rickettsia sp. isolates, 95 Coxiella burnetii isolates, and 135 Bartonella sp. isolates. Based on our experience with the growth of fastidious microorganisms, we have used a centrifugation shell-vial technique called JNSP, for "je ne sais pas" ("I don't know [what I am growing]") for the isolation of other microorganisms. A total of 173 isolates were cultured from the 3,861 clinical samples tested using the JNSP method. Of these, 40 isolates had not been grown before on usual axenic medium. These include 2 Staphylococcus aureus isolates, 7 isolates of Streptococcus sp. and related genera, 6 Mycobacterium sp. isolates, 1 Nocardia asteroides isolate, 1 Actinomyces sp. isolate, 1 Brucella melitensis isolate, 2 Francisella tularensis isolates, 1 Mycoplasma pneumoniae isolate, and 1 Legionella pneumophila isolate. Using this protocol, we have also cultured intracellular bacteria such as Chlamydia trachomatis and we have performed the first culture and establishment of Trophyrema whipplei. Applied in our laboratory, the shell-vial culture generally exhibits a low rate of success. However, in some cases, this technique allowed microbial diagnosis when classical agar procedure and PCR were negative.

Chlamydia pneumoniae infection in HIV-positive patients: prevalence and relationship with lipid profile

OBJECTIVES

The aims of this study were to evaluate the prevalence and impact of Chlamydia pneumoniae infection in HIV-positive patients and to establish the relationship between C. pneumoniae infection and lipid profile.

METHODS

Detection of C. pneumoniae was by polymerase chain reaction (PCR) on Peripheral Blood Mononuclear Cells (PBMCs) collected from 97 HIV-positive patients. Samples were collected after overnight fast in EDTA-treated tubes. On the same day, patients were also tested for routine chemistry, HIV viral load, CD3, CD8 and CD4 cell counts and lipid profile [cholesterol, high-density lipoproteins (HDLs), low-density lipoproteins (LDLs) and triglycerides].

RESULTS

The overall prevalence of C. pneumoniae was 39%. The prevalence of C. pneumoniae was inversely related to the CD4 lymphocyte count (P=0.03). In the naive group, C. pneumoniae-positive patients had both significantly higher HIV load (71 021+/-15 327 vs. 14 753+/-14 924 HIV-1 RNA copies/mL; P=0.03) and lower CD4 cell count (348.0+/-165.4 vs. 541.7+/-294.8; P=0.04) than C. pneumoniae-negative patients. Moreover, treatment-naive patients with C. pneumoniae infection had significantly higher mean levels of cholesterol (185.3+/-56.2 vs. 124.8+/-45.9 mg/dL; P=0.01), triglycerides (117.2+/-74.7 vs. 68+/-27.6 mg/dL; P=0.04) and LDL (122.4+/-60.1 vs. 55.6+/-58 mg/dL; P=0.05) than C. pneumoniae-negative patients.

CONCLUSIONS

These data indicate that, in HIV-positive subjects, C. pneumoniae infection is relatively frequent and is associated with both low CD4 cell count and high HIV load. Furthermore, C. pneumoniae appears to be associated with hyperlipidaemia and might therefore represent a further risk factor for cardiovascolar disease in HIV-positive patients.

Microorganisms resistant to free-living amoebae

Free-living amoebae feed on bacteria, fungi, and algae. However, some microorganisms have evolved to become resistant to these protists. These amoeba-resistant microorganisms include established pathogens, such as Cryptococcus neoformans, Legionella spp., Chlamydophila pneumoniae, Mycobacterium avium, Listeria monocytogenes, Pseudomonas aeruginosa, and Francisella tularensis, and emerging pathogens, such as Bosea spp., Simkania negevensis, Parachlamydia acanthamoebae, and Legionella-like amoebal pathogens. Some of these amoeba-resistant bacteria (ARB) are lytic for their amoebal host, while others are considered endosymbionts, since a stable host-parasite ratio is maintained. Free-living amoebae represent an important reservoir of ARB and may, while encysted, protect the internalized bacteria from chlorine and other biocides. Free-living amoebae may act as a Trojan horse, bringing hidden ARB within the human "Troy," and may produce vesicles filled with ARB, increasing their transmission potential. Free-living amoebae may also play a role in the selection of virulence traits and in adaptation to survival in macrophages. Thus, intra-amoebal growth was found to enhance virulence, and similar mechanisms seem to be implicated in the survival of ARB in response to both amoebae and macrophages. Moreover, free-living amoebae represent a useful tool for the culture of some intracellular bacteria and new bacterial species that might be potential emerging pathogens.

What does the future hold for clinical microbiology?

Emerging infectious diseases (including community-, hospital- and bioterrorism-acquired infections), emerging resistance to antimicrobial agents and increased social demand are increasing the volume and altering the nature of the activities required from clinical microbiology laboratories.

Centralization, an increase in automation and advances in bioinformatics allow clinical microbiology laboratories to keep up with these ever-increasing demands.

Technologies and techniques that are progressing at the moment include rapid molecular detection, identification and genotyping of bacteria; antimicrobial-resistance determination; rapid immunological detection of pathogens; easy-to-use electron microscopy; and data digitalization and the secure online exchange of information.

The future evolution of clinical microbiology might include the spread of 'at-doctor' tests and bedside tests at the same time as specialized diagnoses are centralized in reference laboratories that are connected on national and international scales. Centralization should allow the development of P3/P4 laboratories, molecular-biology platforms, including mass spectrometry, and serology platforms, including antigenic microarrays for serodiagnosis.

Sampling strategies might evolve towards pathology-based sampling kits in accordance with the development of multiplex platforms. In addition, data reporting could be based solely on digitalized figures and could include data interpretation and the addition of electronic links to up-to-date literature, which can be exchanged in a timely manner through the Internet.

Large clinical microbiology laboratories could engage in the regular reporting of epidemiological trends for pathogens, pathogen subtypes and antimicrobial resistance.

These anticipated changes will require the advanced training of technicians in bioinformatics, and the creation of posts for maintenance workers and engineers for the continuous implementation of new techniques. Clinical microbiologists will have an increased role in communicating with infectious-disease practitioners in the interpretation and delivery of results, with consultants in diagnosis and antimicrobial treatment, and in strategic laboratory management.

In the past decade, clinical microbiology laboratories have undergone important changes with the introduction of molecular biology techniques and laboratory automation. In the future, there will be a need for more rapid diagnoses, increased standardization of testing and greater adaptability to cope with new threats from infectious microorganisms, such as agents of bioterrorism and emerging pathogens. The combination of the new tools that are now being developed in research laboratories, the general reorganization of clinical laboratories and improved communication between physicians and clinical microbiologists should lead to profound changes in the way that clinical microbiologists work.

The traveller and emerging infections: sentinel, courier, transmitter

The movement of populations shapes the patterns and distribution of infectious diseases globally. The consequences of travel are seen in the traveller and in places and populations visited and may persist long after travel. The traveller can be seen as an interactive biological unit who picks up, processes, carries and drops off microbial genetic material. A traveller can introduce potential pathogens in the absence of signs or symptoms of illness. Travellers can serve as a sentinel population; study of them can provide insights into the presence and level of risk of transmission of infections in other geographical regions. Travellers can also be seen as couriers who inadvertently ferry pathogens and microbial genetic material to regions where researchers can carry out detailed analyses that can help to map the location and movement of strains, genotypes and resistance patterns. The laboratory plays a key role in the identification and characterization of pathogens, which can inform management of individual patients and the public health response. The connectedness and mobility in the world today facilitate the emergence of infectious diseases in humans and also in animals and plants. Many traditional barriers have been breached by travel, roads and technology. Population size and density favour spread of many infections. The rapid generation time of microbes and their capacity to adapt to changes in the physico-chemical and immunological environment will pose continuing challenges.

Bordetella pertussis PCR: simultaneous targeting of signature sequences

The absence of analytical controls for polymerase chain reaction (PCR)-based diagnostic tests for Bordetella pertussis limits their clinical utility. In this study, multiplex PCR simultaneously targeted two specific Bordetella pertussis sequences, the chromosomal repeated insertion sequence IS481 (IS) and the pertussis toxin promoter region (PT). A multi-target hybridization-EIA (Hyb-EIA) method in a 96-well microtiter-plate format was used to detect amplicons. Forty-seven (15%) of the 318 nasopharygeal specimens tested positive for at least one DNA target of B. pertussis by PCR, including the 10 known positive samples by culture and/or direct fluorescent antibody (DFA). Forty-six of the 47 PCR positive samples were considered positive for B. pertussis using the consensus interpretation criteria. Simultaneous detection of multiple chromosomal regions may identify false-positive and -negative results due to analytical variations or potential sequence polymorphism, and uncover a wider range of pathogenic strains.