Simultaneous Detection of Key Bacterial Pathogens Related to Pneumonia and Meningitis Using Multiplex PCR Coupled With Mass Spectrometry

Multiplex detection of bacterial pathogens by PCR/SERS assay

Bacterial infections are a leading cause of death globally. The detection of DNA sequences correlated to the causative pathogen has become a vital tool in medical diagnostics. In practice, PCR-based assays for the simultaneous detection of multiple pathogens currently rely on probe-based quantitative strategies that require expensive equipment but have limited sensitivity or multiplexing capabilities. Hence, novel approaches to address the limitations of the current gold standard methods are still in high demand. In this study, we propose a simple multiplex PCR/SERS assay for the simultaneous detection of four bacterial pathogens, namely P. aeruginosa, S. aureus, S. epidermidis, and M. smegmatis. Wherein, specific primers for amplifying each target gDNA were applied, followed by applying SERS nanotags functionalized with complementary DNA probes and Raman reporters for specific identification of the target bacterial pathogens. The PCR/SERS assay showed high specificity and sensitivity for genotyping bacterial pathogen gDNA, whereby as few as 100 copies of the target gDNA could be detected. With high sensitivity and the convenience of standard PCR amplification, the proposed assay shows great potential for the sensitive detection of multiple pathogen infections to aid clinical decision-making.

Fast detection of bacterial gut pathogens on miniaturized devices: an overview

INTRODUCTION

Gut microbes pose challenges like colon inflammation, deadly diarrhea, antimicrobial resistance dissemination, and chronic disease onset. Development of early, rapid and specific diagnosis tools is essential for improving infection control. Point-of-care testing (POCT) systems offer rapid, sensitive, low-cost and sample-to-answer methods for microbe detection from various clinical and environmental samples, bringing the advantages of portability, automation, and simple operation.

AREAS COVERED

Rapid detection of gut microbes can be done using a wide array of techniques including biosensors, immunological assays, electrochemical impedance spectroscopy, mass spectrometry and molecular biology. Inclusion of Internet of Things, machine learning, and smartphone-based point-of-care applications is an important aspect of POCT. In this review, the authors discuss various fast diagnostic platforms for gut pathogens and their main challenges.

EXPERT OPINION

Developing effective assays for microbe detection can be complex. Assay design must consider factors like target selection, real-time and multiplex detection, sample type, reagent stability and storage, primer/probe design, and optimizing reaction conditions for accuracy and sensitivity. Mitigating these challenges requires interdisciplinary collaboration among scientists, clinicians, engineers, and industry partners. Future efforts are essential to enhance sensitivity, specificity, and versatility of POCT systems for gut microbe detection and quantification, advancing infectious disease diagnostics and management.

Evaluation of nucleotide MALDI-TOF-MS for the identification of Mycobacterium species

Background

The accurate identification of the Mycobacterium tuberculosis complex (MTBC) and different nontuberculous mycobacteria (NTM) species is crucial for the timely diagnosis of NTM infections and for reducing poor prognoses. Nucleotide matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) has been extensively used for microbial identification with high accuracy and throughput. However, its efficacy for Mycobacterium species identification has been less studied. The objective of this study was to evaluate the performance of nucleotide MALDI-TOF-MS for Mycobacterium species identification.

Methods

A total of 933 clinical Mycobacterium isolates were preliminarily identified as NTM by the MPB64 test. These isolates were identified by nucleotide MALDI-TOF-MS and Sanger sequencing. The performance of nucleotide MALDI-TOF MS for identifying various Mycobacterium species was analyzed based on Sanger sequencing as the gold standard.

Results

The total correct detection rate of all 933 clinical Mycobacterium isolates using nucleotide MALDI-TOF-MS was 91.64% (855/933), and mixed infections were detected in 18.65% (174/933) of the samples. The correct detection rates for Mycobacterium intracellulare, Mycobacterium abscessus, Mycobacterium kansasii, Mycobacterium avium, MTBC, Mycobacterium gordonae, and Mycobacterium massiliense were 99.32% (585/589), 100% (86/86), 98.46% (64/65), 94.59% (35/37), 100.00% (34/34), 95.65% (22/23), and 100% (19/19), respectively. For the identification of the MTBC, M. intracellulare, M. abscessus, M. kansasii, M. avium, M. gordonae, and M. massiliense, nucleotide MALDI-TOF-MS and Sanger sequencing results were in good agreement (k > 0.7).

Conclusion

In conclusion, nucleotide MALDI-TOF-MS is a promising approach for identifying MTBC and the most common clinical NTM species.

A sensitive mass spectrometry-based method to identify common respiratory pathogens in children

Public health threats posed by emerging respiratory infections are a significant concern, particularly in children and infants. Traditional culture-based detection methods are time-consuming and typically require 1-3 days. Herein, we developed and evaluated a 23-plex common respiratory pathogen mass spectrometry assay that enables the simultaneous detection of 18 common respiratory pathogens in children. This assay combines matrix-assisted laser desorption/ionization time of flight mass spectrometry with multiplex reverse transcription-PCR and targets 11 bacterial and 7 viral pathogens (including 10 subtypes), and two internal controls. The detection limit of the common respiratory pathogen mass spectrometry assay was as low as 1 copy/µL, with no cross-reactivity with other organisms. We assessed the clinical performance of the common respiratory pathogen mass spectrometry assay using respiratory samples from 450 children. The total 450 clinical specimens underwent analysis via matrix-assisted laser desorption/ionization time of flight mass spectrometry, and the outcomes were juxtaposed with those derived from real-time reverse-transcriptase PCR conducted concurrently. The concordance between these methods was 96.0%, and the multiple infection identification rate was 7.1%. This innovative approach enables the simultaneous analysis of numerous outcomes from a solitary examination across 192 specimens within a timeframe of approximately 7 hours, with a dramatically reduced sample use and cost. In summary, the common respiratory pathogen mass spectrometry assay is a sensitive, accurate, and cost-effective method for detecting common respiratory pathogens in children and has the potential to revolutionize the diagnosis of respiratory tract infections. IMPORTANCE This study aimed to present and evaluate a novel co-detection method that enables the simultaneous identification of 11 bacterial and 7 viral pathogens in about 7 hours using matrix-assisted laser desorption/ionization time of flight mass spectrometry. Our approach utilizes a combination of multiplex reverse transcription-PCR and matrix-assisted laser desorption/ionization time of flight mass spectrometry, which overcomes the limitations of conventional assays, which include a long assessment time, technical difficulty, and high costs. As a screening method for common respiratory pathogens in children, common respiratory pathogen mass spectrometry assay has the potential to revolutionize the diagnosis of respiratory tract infections by providing an accurate etiological diagnosis. The common respiratory pathogen mass spectrometry assay is expected to be a critical tool for the diagnosis of respiratory infections in children, offering a more efficient, cost-effective, and accurate approach for the detection of common respiratory pathogens.

“Omic” Approaches to Bacteria and Antibiotic Resistance Identification

The quick and accurate identification of microorganisms and the study of resistance to antibiotics is crucial in the economic and industrial fields along with medicine. One of the fastest-growing identification methods is the spectrometric approach consisting in the matrix-assisted laser ionization/desorption using a time-of-flight analyzer (MALDI-TOF MS), which has many advantages over conventional methods for the determination of microorganisms presented. Thanks to the use of a multiomic approach in the MALDI-TOF MS analysis, it is possible to obtain a broad spectrum of data allowing the identification of microorganisms, understanding their interactions and the analysis of antibiotic resistance mechanisms. In addition, the literature data indicate the possibility of a significant reduction in the time of the sample preparation and analysis time, which will enable a faster initiation of the treatment of patients. However, it is still necessary to improve the process of identifying and supplementing the existing databases along with creating new ones. This review summarizes the use of “-omics” approaches in the MALDI TOF MS analysis, including in bacterial identification and antibiotic resistance mechanisms analysis.

Rapid Detection of Antimicrobial Resistance in Mycoplasma genitalium by High-Resolution Melting Analysis with Unlabeled Probes

With looming resistance to fluoroquinolones in Mycoplasma genitalium, public health control strategies require effective antimicrobial resistance (AMR) diagnostic methods for clinical and phenotypic AMR surveillance. We developed a novel AMR detection method, MGparC-AsyHRM, based on the combination of asymmetric high-resolution melting (HRM) technology and unlabeled probes, which simultaneously performs M. genitalium identification and genotypes eight mutations in the parC gene that are responsible for most cases of fluoroquinolone resistance. These enhancements expand the traditional HRM from the conventional detection of single-position mutations to a method capable of detecting short fragments with closely located AMR positions with a high diversity of mutations. Based on the results of clinical sample testing, this method produces an accordance of 98.7% with the Sanger sequencing method. Furthermore, the specificity for detecting S83I, S83N, S83R, and D87Y variants, the most frequently detected mutations in fluoroquinolone resistance, was 100%. This method maintained a stable and accurate performance for genomic copies at rates of ≥20 copies per reaction, demonstrating high sensitivity. Additionally, no specific cross-reactions were observed when testing eight common sexually transmitted infection (STI)-related agents. Notably, this work highlights the significant potential of our method in the field of AMR testing, with the results suggesting that our method can be applied in a range of scenarios and to additional pathogens. In summary, our method enables high throughput, provides excellent specificity and sensitivity, and is cost-effective, suggesting that this method can be used to rapidly monitor the molecular AMR status and complement current AMR surveillance. IMPORTANCE Mycoplasma genitalium was recently added to the antimicrobial-resistant (AMR) threats "watch list" of the U.S. Centers for Disease Control and Prevention because this pathogen has become extremely difficult to treat as a result of increased resistance. M. genitalium is also difficult to culture, and therefore, molecule detection is the only method available for AMR testing. In this work, we developed a novel AMR detection method, MGparC-AsyHRM, based on the combination of asymmetrical HRM technology and unlabeled probes, and it simultaneously performs M. genitalium identification and genotypes eight mutations in the parC gene that are responsible for most cases of fluoroquinolone resistance. The MGparC-AsyHRM method is a high-throughput, low-cost, simple, and culture-free procedure that can enhance public health and management of M. genitalium infections and AMR control, providing a strong complement to phenotypic AMR surveillance to address the spread of fluoroquinolone resistance.

Comprehensive Description of Pathogens and Antibiotic Treatment Guidance in Children With Community-Acquired Pneumonia Using Combined Mass Spectrometry Methods

The objective of this study was to evaluate the value of molecular methods in the management of community-acquired pneumonia (CAP) in children. Previously developed mass spectrometry (MS)-based methods combined with quantitative real-time PCR (combined-MS methods) were used to describe the aetiology and evaluate antibiotic therapy in the enrolled children. Sputum collected from 302 children hospitalized with CAP were analyzed using the combined-MS methods, which can detect 19 viruses and 12 bacteria related to CAP. Based on the results, appropriate antibiotics were determined using national guidelines and compared with the initial empirical therapies. Respiratory pathogens were identified in 84.4% of the patients (255/302). Co-infection was the predominant infection pattern (51.7%, 156/302) and was primarily a bacterial-viral mixed infection (36.8%, 111/302). Compared with that using culture-based methods, the identification rate for bacteria using the combined-MS methods (61.8%, 126/204) increased by 28.5% (p <0.001). Based on the results of the combined-MS methods, the initial antibiotic treatment of 235 patients was not optimal, which mostly required switching to β-lactam/β-lactamase inhibitor combinations or reducing unnecessary macrolide treatments. Moreover, using the combined-MS methods to guide antibiotic therapy showed potential to decrease the length of stay in children with severe CAP. For children with CAP, quantitative molecular testing on sputum can serve as an important complement to traditional culture methods. Early aetiology elucidated using molecular testing can help guide the antibiotic therapy.

A multiplex assay for characterization of antimicrobial resistance in Neisseria gonorrhoeae using multi-PCR coupled with mass spectrometry

BACKGROUND

Complicated mechanisms and variable determinants related to drug resistance pose a major challenge to obtain comprehensive antimicrobial resistance (AMR) profiles of Neisseria gonorrhoeae. Meanwhile, cephalosporin-resistant mosaic penA alleles have been reported worldwide. Therefore, it is urgent to monitor the expansion of cephalosporin-resistant mosaic penA alleles.

OBJECTIVES

To develop a comprehensive high-throughput method to efficiently screen AMR determinants.

METHODS

We developed a method based on multiplex PCR with MALDI-TOF MS, which can simultaneously screen for 24 mutations associated with multiple antimicrobial agents in 19 gonococcal AMR loci (NG-AMR-MS). The performance of the NG-AMR-MS method was assessed by testing 454 N. gonorrhoeae isolates with known MICs of six antibiotics, eight non-gonococcal Neisseria strains, 214 clinical samples and three plasmids with a confirmed mosaic penA allele.

RESULTS

The results show that NG-AMR-MS had a specificity of 100% with a sensitivity as low as 10 copies per reaction (except for PorB A121D/N/G, 100 copies per reaction). For clinical samples with gonococcal load >5 copies/μL, the method can accurately identify 20 AMR mutations. In addition, the method successfully detected specific cephalosporin-resistant strains with the A311V mutation in the penA allele.

CONCLUSIONS

Our high-throughput method can provide comprehensive AMR profiles within a multiplex format. Furthermore, the method can be directly applied to screening for AMR among clinical samples, serving as an effective tool for overall monitoring of N. gonorrhoeae AMR and also provides a powerful means to comprehensively improve the level of monitoring.

Multiplexed detection of bacterial pathogens based on a cocktail of dual-modified phages

Rapid, quantitative, and sensitive assays for the multiplexed detection of bacterial pathogens are urgently needed for public health. Here, we report the generation of dual-modified phage sensors for the simultaneous detection of multiple pathogenic bacteria. The M13KE phage was dual modified to display the targeting peptide on the minor coat protein pIII (∼5 copies) and the streptavidin-binding (StrB) peptide on the major coat protein pVIII (∼2700 copies). The targeting peptide specifically recognizes the target bacteria, and the StrB peptide acts as the efficient signal amplification and transduction unit upon binding with fluorescently tagged streptavidin. The bright fluorescence emitted from individual target bacteria can be clearly distinguished from the background via both the flow cytometry and fluorescence microscopy. Three different dual-modified phages targeting E. coli O157:H7, Salmonella Typhimurium, and Pseudomonas aeruginosa were constructed, and high specificity was verified via a large excess of other non-target bacteria. Using a 40 mL sample volume, the target bacteria detection limit was approximately 10² cells/mL via flow cytometry measurement in the presence of other non-target bacteria. By combining these three dual-modified phages into a cocktail, simultaneous detection and quantification of three target bacterial pathogens was demonstrated with good linearity. The strategy of constructing dual-modified phage represents a promising tool in the detection of bacterial pathogens.

Ficolin-1 gene (FCN1) -144 C/A polymorphism is associated with adverse outcome of severe pneumonia in the under-five Egyptian children: A multicenter study

BACKGROUND

Pneumonia is the foremost cause of child death worldwide. M-ficolin is encoded by the FCN1 gene and represents a novel link between innate and adaptive immunity.

OBJECTIVES

To investigate the FCN1 -144 C/A (rs10117466) polymorphism as a potential marker for pneumonia severity and adverse outcome namely complications or mortality in the under-five Egyptian children.

METHODS

This was a prospective multicenter study that included 620 children hospitalized with World Health Organization-defined severe pneumonia and 620 matched healthy control children. Polymorphism rs10117466 of the FCN1 gene promoter was analyzed by PCR-SSP, while serum M-ficolin levels were assessed by ELISA.

RESULTS

The FCN1 A/A genotype and A allele at the -144 position were more frequently observed in patients compared to the control children (43.4% vs 27.6%; odds ratio [OR]: 1.62; [95% confidence interval {CI}: 1.18-2.2]; for the A/A genotype) and (60.8% vs 52.5%; OR: 1.4; [95% CI: 1.19-1.65]; for the A allele); P < .01. The FCN1 -144 A/A homozygous patients had significantly higher serum M-ficolin concentrations (mean: 1844 ± 396 ng/mL) compared with those carrying the C/C or C/A genotype (mean: 857 ± 278 and 1073 ± 323 ng/mL, respectively; P = .002). FCN1 -144 A/A genotype was an independent risk factor for adverse outcomes in children with severe pneumonia (adjusted OR = 4.85, [95% CI: 2.96-10.25]; P = .01).

CONCLUSION

The FCN1 A/A genotype at the -144 position was associated with high M-ficolin serum levels and possibly contributes to enhanced inflammatory response resulting in the adverse outcome of pneumonia in the under-five Egyptian children.

Simultaneous detection of eleven sexually transmitted agents using multiplexed PCR coupled with MALDI-TOF analysis

Purpose

Sexually transmitted infections (STIs), representing a major global health problem, are caused by different microbes, including bacteria, viruses, and protozoa. Unfortunately, infections of different sexually transmitted pathogens often present similar clinical symptoms, so it is almost impossible to distinguish them clinically. Therefore, the aim of the current study was to develop a sensitive, multitarget, and high-throughput method that can detect various agents responsible for STIs.

Methods

We developed and tested a 23-plex PCR coupled with matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) assay (sexually transmitted infection-mass spectrometry, STI-MS) that simultaneously targets 11 different agents, including 8 most common clinical pathogens related to STIs (HSV-1, HSV-2, Neisseria gonorrhoeae, Chlamydia trachomatis, Treponema pallidum, Trichomonas vaginalis, Mycoplasma genitalium, and Haemophilus ducreyi) and 3 controversial microorganisms as pathogens (Mycoplasma hominis, Ureaplasma urealyticum, and Ureaplasma parvum).

Results

The results showed that the STI-MS approach can accurately detect the expected agents, without cross-reaction with other organisms. The limit of detection of each STI-MS assay was ranged from 1.739 to 10.009 copies/reaction, using probit analyses. The verification rate for each target organism of the STI-MS ranged from a minimum of 89.3% to a maximum of 100%, using conventional assays and ultrasensitive digital PCR to confirm the STI-MS-positive results. To further evaluate the clinical performance of this assay, 241 clinical specimens (124 urethral/cervical swabs and 117 urine) were tested in parallel using the STI-MS assay and monoplex real-time PCR for each agent. The overall validation parameters of STI-MS were extremely high including sensitivity (from 85.7% to 100%), specificity (from 92.3% to 100%), PPV (from 50% to 100%), and NPV (from 99.1% to 100%) for each target.

Conclusion

STI-MS is a useful high-throughput screening tool for detecting mixed infections of STIs and has great potential for application in large-scale epidemiological programs for specific microorganisms of STI.

Multicolor and Ultrasensitive Enzyme-Linked Immunosorbent Assay Based on the Fluorescence Hybrid Chain Reaction for Simultaneous Detection of Pathogens

Various pathogens may coexist in one sample; however, detection methods that rely on traditional selective culture media or immune agents designed specifically for a certain target are unsuitable for multiple targets. It is important to develop a simultaneous and sensitive detection method for multiple pathogens. Here, a multicolor and ultrasensitive enzyme-linked immunosorbent assay (ELISA) platform based on the fluorescence hybridization chain reaction (HCR) was developed. In the assay, multicolor fluorescence concatemers formed as signal amplifiers and signal reporters in the presence of target pathogens. When HCR occurred, Escherichia coli O157:H7, Salmonella serotype Choleraesuis, and Listeria monocytogenes were detected simultaneously with three different fluorescences. Additionally, the limits of detection for E. coli O157:H7, Salmonella Choleraesuis, and L. monocytogenes were 3.4 × 10¹, 6.4 × 10⁰, and 7.0 × 10¹ CFU/mL, respectively. The assay achieved ultrasensitive, specific, and simultaneous detection of three pathogens and can be applied to the detection of pathogens in milk samples. Therefore, this multicolor and ultrasensitive ELISA platform has great potential in the application of simultaneous detection of pathogens.

Detection of 12 Common Food-Borne Bacterial Pathogens by TaqMan Real-Time PCR Using a Single Set of Reaction Conditions

Food safety has become an important public health issue worldwide. However, conventional methods for detection of food-borne pathogens are complicated, and labor-intensive. Moreover, the sensitivity is often low, and it is difficult to achieve high-throughput detection. This study developed a TaqMan real-time polymerase chain reaction (PCR) assay for the simultaneous detection and quantification of 12 common pathogens in a single reaction, including Escherichia coli O157:H7, Listeria monocytogenes/ivanovii, Salmonella enterica, Vibrio parahaemolyticus, β-streptococcus hemolyticus, Yersinia enterocolitica, Enterococcus faecalis, Shigella spp., Proteus mirabilis, Vibrio fluvialis, Staphylococcus aureus, and Campylobacter jejuni in food and drinking water. Based on published sequence data, specific primers, and fluorescently-labeled hybridization probes were designed targeting based on the virulence genes of the 12 pathogens, and these primers and probes were optimized to achieve consistent reaction conditions. The assay was evaluated using 106 pure bacterial culture strains. There was no cross-reaction among the different pathogens. The analytical sensitivity was 1 copy/μL for E. coli O157:H7, L. monocytogenes/ivanovii, β-streptococcus hemolyticus, Shigella spp., P. mirabilis, and V. fluvialis, 10 copies/μL for S. enterica, V. parahaemolyticus, Y. enterocolitica, E. faecalis, S. aureus, and C. jejuni, respectively. The limit of detection (LOD) was 296, 500, 177, 56, 960, 830, 625, 520, 573, 161, 875, and 495 CFU/mL for E. coli O157:H7, L. monocytogenes/ivanovii, S. enterica, V. parahaemolyticus, β-streptococcus hemolyticus, Y. enterocolitica, E. faecalis, Shigella spp., P. mirabilis, V. fluvialis, S. aureus, and C. jejuni, respectively. The limit of detection for the assay in meat samples was 10³ CFU/g for V. parahaemolyticus and 10⁴ CFU/g for other 11 strains. Together, these results indicate that the optimized TaqMan real-time PCR assay will be useful for routine detection of pathogenic bacteria due to its rapid analysis, low cost, high-throughput, high specificity, and sensitivity.

Magnetism-Resolved Separation and Fluorescence Quantification for Near-Simultaneous Detection of Multiple Pathogens

In the modern era of molecular evidence-based medicine and advanced biomedical technologies, the rapid, sensitive and specific assay of multiple pathogens is critical to, but largely absent from, clinical practice. Therefore, to improve the current ordinary separation and collection method, we report herein a strategy of magnetism-resolved separation and fluorescence quantification for near-simultaneous detection of multiple pathogens, followed by the direct antimicrobial susceptibility testing (AST). To accomplish this strategy, we utilized aptamer-modified fluorescent-magnetic multifunctional nanoprobes (apt-FMNPs). FMNPs with intriguing different magnetic responses and excellent fluorescence quality were first self-assembled based on metal coordination interaction using (3-mercaptopropyl) trimethoxysilane, magnetic γ-Fe₂O₃, and fluorescent quantum dots as matrix components. Then, aptamers, which specific to target pathogens of Escherichia coli O157:H7 ( E. coli) and Salmonella typhimurium ( S. typ), were conjugated with FMNPs to yield apt-FMNPs nanoprobes for multiple pathogens assay. Based on the discrepant magnetic response of pathogen@nanoprobes complex under the identical external magnetic field, the model bacteria were fished out by magnetic adsorption at different time points and subjected to fluorescence quantification with good linear ranges and detection limits within 1h. Multiple pathogens spiked in real samples were also effectively detected by the apt-FMNPs and sequentially fished out for AST assay, which showed similar results to that for pure pathogens. The apt-FMNPs-based strategy of near-simultaneous detection of multiple pathogens shows promise for the potential application in the diagnosis and treatment of pathogen-related infectious diseases.