Clinical evaluation of a direct fluorescent monoclonal antibody test for detection of Pseudomonas aeruginosa in blood cultures

Aptamer-based biosensors for Pseudomonas aeruginosa detection

Pseudomonas aeruginosa possesses innate antibiotic resistance mechanisms, and carbapenem-resistant Pseudomonas aeruginosa has been considered the number one priority in the 2017 WHO list of antimicrobial-resistant crucial hazards. Early detection of Pseudomonas aeruginosa can circumvent treatment challenges. Various techniques have been developed for the detection of P. aeruginosa detection. Biosensors have recently attracted unprecedented attention in the field of point-of-care diagnostics due to their easy operation, rapid, low cost, high sensitivity, and selectivity. Biosensors can convert the specific interaction between bioreceptors (antibodies, aptamers) and pathogens into optical, electrical, and other signal outputs. Aptamers are novel and promising alternatives to antibodies as biorecognition elements mainly synthesized by systematic evolution of ligands by exponential enrichment and have predictable secondary structures. They have comparable affinity and specificity for binding to their target to antibody recognition. Since 2015, there have been about 2000 journal articles published in the field of aptamer biosensors, of which 30 articles were on the detection of P. aeruginosa. Here, we have focused on outlining the recent progress in the field of aptamer-based biosensors for P. aeruginosa detection based on optical, electrochemical, and piezoelectric signal transduction methods.

Detection methods for Pseudomonas aeruginosa: history and future perspective

The current review summarized and analyzed the development of detection techniques forPseudomonas aeruginosaover the past 50 years.

DNA capturing machinery through spore-displayed proteins

AIMS

The purpose of this study was to develop a general method for the facile development of a new DNA biosensor which utilizes streptavidin-displayed spores as a molecular machinery.

METHODS AND RESULTS

Fluorescence spectroscopy was used as a monitoring tool for the streptavidin displayed on the surface of Bacillus thuringiensis spores and as a diagnosis method for DNA detection. As a proof-of-concept, four pathogenic bacteria including Pseudomonas aeruginosa, Acinetobacter baumannii, Escherichia coli and Klebsiella pneumonia were used for the detection of pathogenic species. In addition, a set of mutant variants of Wilson's disease were also used for the detection of single nucleotide polymorphism (SNP) in this system.

CONCLUSIONS

This strategy, utilizing streptavidin-displayed spores, is capable of capturing DNA targets for the detection of pathogenic bacteria and for mutation analysis in Wilson's disease.

SIGNIFICANCE AND IMPACT OF THE STUDY

This approach could be useful as a simple platform for developing sensitive spore-based biosensors for any desired DNA targets in diagnostic applications.

Monoclonal antibody S60-4-14 reveals diagnostic potential in the identification of Pseudomonas aeruginosa in lung tissues of cystic fibrosis patients

The lipopolysaccharide (LPS) of Pseudomonas aeruginosa has been identified to contain an inner-core structure expressing a Pseudomonas-specific epitope. This target structure is characterized by a highly phosphorylated and 7-O-carbamoyl-l-glycero-alpha-d-manno-heptopyranose (CmHep) and was found to be present in all human-pathogenic Pseudomonas species of the Palleroni (RNA)-classification I scheme. We raised and selected the monoclonal antibody S60-4-14 (mAb S60-4-14, subtype IgG1) from mice immunized with heat-killed Pseudomonas bacteria. The epitope of this mAb was found to reside in the inner-core structure of P. aeruginosa and, hence, successfully evaluated for the immunohistochemical detection of P. aeruginosa in formalin- or HOPE-fixed (Hepes-glutamic acid buffer-mediated organic solvent protection effect) and paraffin-embedded human lung tissue slices. Lung specimens, mainly from explanted lungs of cystic fibrosis (CF) patients, as well as P. aeruginosa isolates from patients suffering from CF and patients with extrapulmonar Pseudomonas infections were investigated by PCR, immunohistochemistry, and Western blot analysis with mAb S60-4-14. The results revealed an unequivocal coincidence of PCR and immunohistochemistry. Together with the Western blot results mAb S60-4-14 displays a potential diagnostic tool for the specific identification of P. aeruginosa in infected lungs of CF.

DNA microarray-based detection of nosocomial pathogenic Pseudomonas aeruginosa and Acinetobacter baumannii

Infection by nosocomial pathogenic bacteria is increasingly becoming a major threat to the patients in the hospital. We have developed a diagnostic DNA microarray for the detection of two important nosocomial pathogens, Pseudomonas aeruginosa and Acinetobacter baumannii. The diagnostic DNA microarray contains the species-specific probes of 15mer oligonucleotides designed based on the sequences of 23S ribosomal DNA. The performance of DNA microarray in diagnosing P. aeruginosa and A. baumannii was evaluated using reference bacteria as well as clinical specimens such as blood, stool, pus, sputum, urine and cerebrospinal fluid. Using this DNA microarray, A. baumannii could be successfully detected in 11 out of 13 clinical specimens, thus giving the sensitivity of 84.6% with the specificity of 100% and the positive predictive value of 100%. P. aeruginosa could also be detected in 25 out of 26 clinical specimens, showing the sensitivity of 96.2%, the specificity of 100%, and the positive predictive value of 100%. These results suggest that two nosocomial pathogens, P. aeruginosa and A. baumannii, can be efficiently diagnosed by using the DNA microarray developed in this study.

Real-time identification of Pseudomonas aeruginosa direct from clinical samples using a rapid extraction method and polymerase chain reaction (PCR)

Pseudomonas aeruginosa has emerged as one of the most problematic Gram-negative nosocomial pathogens. Bacteremia caused by P. aeruginosa is clinically indistinguishable from other Gram-negative infections although the mortality rate is higher. This microorganism is also inherently resistant to common antibiotics. Standard bacterial identification and susceptibility testing is normally a 48-hour process and difficulty sometimes exists in rapidly and accurately identifying antimicrobial resistance. The Polymerase Chain Reaction (PCR) is a rapid and simple process for the amplification of target DNA sequences. However, many sample preparation methods are unsuitable for the clinical laboratory because they are not cost effective, take too long to perform, or do not provide a good template for PCR. Our goal was to provide same-day results to facilitate rapid diagnosis. In this report, we have utilized our rapid DNA extraction method to generate bacterial DNA direct from clinical samples for PCR. The lower detection level for P. aeruginosa was estimated to be 10 CFU/ml. In addition, we wanted to compare the results of a new rapid-cycle DNA thermocycler that uses continuous fluorescence monitoring with the results of standard thermocycling. We tested 40 clinical isolates of P. aeruginosa and 18 non-P. aeruginosa isolates received in a blinded fashion. Coded data revealed that there was 100% correlation in both the rapid-cycle DNA thermocycling and standard thermocycling when compared to standard clinical laboratory results. In addition, total results turn-around time was less than 1 hour. Specific identification of P. aeruginosa was determined using intragenic primer sets for bacterial 16S rRNA and Pseudomonas outer-membrane lipoprotein gene sequences. The total cost of our extraction method and PCR was $2.22 per sample. The accuracy and rapidness of this DNA-extraction method, with its PCR-based identification system, make it an ideal candidate for use in the clinical laboratory.