Rapid identification and characterization of Penicillium marneffei using multiplex ligation-dependent probe amplification (MLPA) in paraffin-embedded tissue samples

Serum Sphingolipids Aiding the Diagnosis of Adult HIV-Negative Patients with Talaromyces marneffei Infection

Increasing attention has been directed to Talaromyces marneffei (T. marneffei) infection in HIV-negative patients due to its high mortality rate. However, nonspecific symptoms and biological characteristics similar to those of other common pathogenic fungi complicate the rapid and accurate diagnosis of T. marneffei infection. Sphingolipids (SPLs) are bioactive lipids involved in the regulation of various physiological and pathological processes and have been identified as serum biomarkers for several diseases. This study employed a sphingolipidomic approach established in our previous work to explore the use of serum SPLs in the diagnosis of HIV-negative patients with T. marneffei infection. Additional clinical cohorts of patients infected with other microorganisms were also recruited. We found that sphinganine (Sa) (d16:0) exhibited obvious depletion after infection; moreover, its level in patients with T. marneffei infection was significantly lower than that in patients infected with other microorganisms. Therefore, Sa (d16:0) was considered a specific diagnostic biomarker for T. marneffei infection, and 302.71 nM was selected as the optimal cutoff value with a diagnostic sensitivity of 87.5% and specificity of 100%. These results suggested that determination of serum Sa (d16:0) levels can be used as a new alternative tool for the rapid diagnosis of T. marneffei infection in HIV-negative patients.

Recurrent Talaromyces marneffei Infection Presenting with Intestinal Obstruction in a Patient with Systemic Lupus Erythematosus

Talaromyces marneffei is an important opportunistic pathogen mainly afflicting the HIV-infected patients, in rare instance, it could cause infection in non-HIV-infected individuals. We report a 51-year-old Chinese woman who, with histories of SLE for 14 years and disseminated talaromycosis for 4 years, occurred partial intestinal obstruction that was demonstrated to be caused by Talaromyces marneffei infection. The randomly amplified polymorphic DNA results of paraffin-embedded tissues from both the present episode and the previous infection suggested that the present infection was a recurrent. The patient was performed excision of involved intestine and treated with oral itraconazole at a daily dose of 400 mg for 3 months, leading to an excellent response. However, she died with unknown reason more than a year later. We also reviewed the literature on Talaromyces marneffei infection associated with SLE as well as intestinal talaromycosis alone.

Rapid and robust identification of clinical isolates of Talaromyces marneffei based on MALDI-TOF mass spectrometry or dimorphism in Galleria mellonella

Talaromyces marneffei is a thermally dimorphic fungal pathogen that causes serious infections particularly in patients with human immunodeficiency virus (HIV). Although the mould form typically produces a characteristic red-diffusing pigment, and conidia from penicillate heads, several nonpathogenic Talaromyces/Penicillium species are morphologically and phenotypically similar. While those other species do not exhibit thermal dimorphism, conversion of T. marneffei to the distinctive fission yeast form in vitro is arduous and frequently incomplete. Here we show that T. marneffei can be rapidly and unambiguously discriminated from related nonpathogenic Talaromyces/Penicillium spp., either by matrix-assisted laser desorption ionisation time-of-flight (MALDI-TOF) mass spectrometry or conversion to fission yeast after introduction into Galleria mellonella. Conversion of T. marneffei conidia to the fission yeast form in G. mellonella larvae occurred as early as 24 h post inoculation at 37oC. Identification by MALDI-TOF was possible after supplementation of the commercial Bruker database with in-house mass spectral profiles created from either the yeast or mycelial phase of T. marneffei. In addition, we show that in-house generated mass spectral profiles could be successfully used to identify T. marneffei with a recently published on-line MALDI-TOF database, circumventing the need to create extensive in-house additional databases for rarely encountered fungal pathogens.

Detection of Talaromyces marneffei from Fresh Tissue of an Inhalational Murine Pulmonary Model Using Nested PCR

Penicilliosis marneffei, often consecutive to the aspiration of Talaromyces marneffei (Penicillium marneffei), continues to be one of the significant causes of morbidity and mortality in immunocompromised patients in endemic regions such as Southeast Asia. Improving the accuracy of diagnosing this disease would aid in reducing the mortality of associated infections. In this study, we developed a stable and reproducible murine pulmonary model that mimics human penicilliosis marneffei using a nebulizer to deliver Talaromyces marneffei (SUMS0152) conidia to the lungs of BALB/c nude mice housed in exposure chamber. Using this model, we further revealed that nested PCR was sensitive and specific for detecting Talaromyces marneffei in bronchoalveolar lavage fluid and fresh tissues. This inhalation model may provide a more representative analysis tool for studying the development of penicilliosis marneffei, in addition to revealing that nested PCR has a predictive value in reflecting pulmonary infection.

Evaluation of two molecular techniques for rapid detection of the main dermatophytic agents of tinea capitis

BACKGROUND

Tinea capitis is very common in Western China, with the most widespread aetiological agent being Trichophyton violaceum, while Microsporum canis is prevalent in the remainder of China. Conventional diagnostics and internal transcribed spacer (ITS) sequencing analyses have proven relatively limited due to the close phylogenetic relationship of anthropophilic dermatophytes. Therefore, alternative molecular tools with sufficient specificity, reproducibility and sensitivity are necessary.

OBJECTIVES

To evaluate two molecular techniques [multiplex ligation-dependent probe amplification (MLPA) and rolling circle amplification (RCA)] for rapid detection of the aetiological agents of tinea capitis, T. violaceum and M. canis.

METHODS

Probes of RCA and MLPA were designed with target sequences in the rDNA ITS gene region. Strains tested consist of 31 T. violaceum, 22 M. canis and 24 reference strains of species that are taxonomically close to the target species.

RESULTS

The specificity and reproducibility of RCA and MLPA in detection of T. violaceum and M. canis were both 100% in both species. Sensitivity testing showed that RCA was positive at concentrations down to 1·68 × 10(6) copies of DNA in the TvioRCA probe, and 2·7 × 10(8) copies of DNA in McRCA. MLPA yielded positive results at concentrations of DNA down to 1·68 × 10(1) copies in the TvioMLPA probe and 2·7 × 10(2) in McMLPA.

CONCLUSIONS

The two techniques were sufficiently specific and sensitive for discriminating the target DNA of T. violaceum and M. canis from that of closely related dermatophytes. RCA and MLPA are advantageous in their reliability and ease of operation compared with standard polymerase chain reaction and conventional methods.

Evaluation of the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry Bruker Biotyper for identification of Penicillium marneffei, Paecilomyces species, Fusarium solani, Rhizopus species, and Pseudallescheria boydii

We evaluated the performance of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), the MALDI Bruker Biotyper system (microflex LT; Bruker Daltonik GmbH, Bremen, Germany), on the identification of 50 isolates of clinically encountered molds, including Penicillium marneffei (n = 28), Paecilomyces species (n = 12), Fusarium solani (n = 6), Rhizopus species (n = 3), and Pseudallescheria boydii (n = 1). The isolates were identified to species levels by sequence analysis of the internal transcribed spacer (ITS) regions using primers ITS1 and ITS4. None of the 28 genetically well characterized isolates of P. marneffei were identified as P. marneffei by MALDI-TOF MS, because P. marneffei was not present in either Bruker general library (DB 5627) or Bruker filamentous fungi library V1.0. However, the rate of accurate identification as P. marneffei (score value ≥ 2.000) was 85.7% based on newly created database from one P. marneffei strain (NTUH-3370) by MALDI Biotyper system. Sequencing analysis of these 22 non-P. marneffei isolates of molds revealed seven Paecilomyces variotii, six F. solani, four Paecilomyces lilacinus, and one each of Paecilomyces sinensis, Rhizopus arrhizus, R. oryzae, R. microspores, and P. boydii. Although all the seven P. variotii isolates, four of the six F. solani, two of the four P. lilacinus, and two of the three isolates of Rhizopus species, and the P. boydii isolate had concordant identification results between MALDI-TOF MS and sequencing analysis, the score values of these isolates were all of <1.700. This study indicated that the MALDI Bruker Biotyper is ineffective for identifying P. marneffei and other unusual molds because of the current database limitations. Therefore, it is necessary to continuously update the MALDI-TOF MS databases.

Three isothermal amplification techniques for rapid identification of Cladophialophora carrionii, an agent of human chromoblastomycosis

In this study, we developed rapid and sensitive assays for the detection of Cladophialophora carrionii, a common agent of human chromoblastomycosis. The isothermal techniques evaluated were rolling-circle amplification (RCA), multiplex ligation-dependent probe amplification (MLPA), and loop-mediated isothermal amplification (LAMP). The probes for RCA and MLPA were designed with target sequences in the rDNA internal transcribed spacer gene (ITS) region, and LAMP primers were designed using the elongation factor 1α gene (EF1); these probes and primers specifically amplified DNA of isolates of the species. The three techniques were sufficiently specific and sensitive for discriminating target DNA of C. carrionii from that of related Cladophialophora species and other agents of chromoblastomycosis. RCA, MLPA, and LAMP are advantageous in their reliability and ease of operation compared to standard PCR and conventional methods.

BeeDoctor, a versatile MLPA-based diagnostic tool for screening bee viruses

The long-term decline of managed honeybee hives in the world has drawn significant attention to the scientific community and bee-keeping industry. A high pathogen load is believed to play a crucial role in this phenomenon, with the bee viruses being key players. Most of the currently characterized honeybee viruses (around twenty) are positive stranded RNA viruses. Techniques based on RNA signatures are widely used to determine the viral load in honeybee colonies. High throughput screening for viral loads necessitates the development of a multiplex polymerase chain reaction approach in which different viruses can be targeted simultaneously. A new multiparameter assay, called "BeeDoctor", was developed based on multiplex-ligation probe dependent amplification (MLPA) technology. This assay detects 10 honeybee viruses in one reaction. "BeeDoctor" is also able to screen selectively for either the positive strand of the targeted RNA bee viruses or the negative strand, which is indicative for active viral replication. Due to its sensitivity and specificity, the MLPA assay is a useful tool for rapid diagnosis, pathogen characterization, and epidemiology of viruses in honeybee populations. "BeeDoctor" was used for screening 363 samples from apiaries located throughout Flanders; the northern half of Belgium. Using the "BeeDoctor", virus infections were detected in almost eighty percent of the colonies, with deformed wing virus by far the most frequently detected virus and multiple virus infections were found in 26 percent of the colonies.

Molecular identification of Clonorchis sinensis and discrimination with other opisthorchid liver fluke species using multiple Ligation-depended Probe Amplification (MLPA)

BACKGROUND

Infections with the opisthorchid liver flukes Clonorchis sinensis, Opisthorchis viverrini, and O. felineus cause severe health problems globally, particularly in Southeast Asia. Early identification of the infection is essential to provide timely and appropriate chemotherapy to patients.

RESULTS

In this study we evaluate a PCR-based molecular identification method, Multiplex Ligation-dependent Probe Amplification (MLPA), which allows rapid and specific detection of single nucleotide acid differences between Clonorchis sinensis, Opisthorchis viverrini and O. felineus. Three probe pairs were derived from the Internally Transcribed Spacer 1 (ITS1) of three opisthorchid liver flukes using a systematic phylogenetic analysis. Specific loci were detected in all three species, yielding three amplicons with 198,172 and 152 bp, respectively, while no cross reactions were observed. A panel of 66 C. sinensis isolates was screened using MLPA. All species were positively identified, and no inhibition was observed. The detection limit was 10(3) copies of the ITS gene for the three liver flukes, or about 60 pg genomic DNA for Clonorchis sinensis. Amplification products can be detected by electrophoresis on agarose gel or in a capillary sequencer. In addition, genomic DNA of Clonorchis sinensis in fecal samples of infected rats was positively amplified by MLPA.

CONCLUSION

The flexibility and specificity make MLPA a potential tool for specific identification of infections by opisthorchid liver flukes in endemic areas.