Detection of common candidemia pathogens based on PCR combined with MALDI-TOF MS / 中华检验医学杂志

Objective:A high-throughput assay for the detection of five common clinical Candidaemia pathogens was established by combining polymerase chain reaction (PCR) and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS).Method:Establishment of methodology. We selected Candida albicans, Candida parapsilosis, Candida glabrata, Candida krusei, Candida tropicalis to be the target pathogens and the internal transcribed spacer (ITS) region as the target gene. Specific single base extension primers were designed to perform single base extension reaction in the same reaction system. MALDI-TOF MS was used to detect the characteristic peaks of each target pathogen. The sensitivity and specificity of the detection system were verified by using spiked blood samples. Totally 108 blood samples from proven or suspected candidaemia patients were collected from October 2021 to September 2022 in a hospital in Beijing. The results of nucleic acid mass spectrometry were compared with those of clinical blood culture. Results:The established nucleic acid mass spectrometry detection system can simultaneously detect five common clinical Candida species. Each strain can produce specific product peaks and there is no mutual interference between the strains. The detection limit of Candida albicans was 100 CFU/ml. The detection limit of Candida parapsilosis, Candida glabrata, Candida krusei and Candida tropicalis was 10 CFU/ml. For the 108 blood samples, the sensitivity, specificity, positive predictive value and negative predictive value of nucleic acid mass spectrometry were 94.74% (36/38), 97.14% (68/70), 92.31% (36/39) and 98.55% (68/69), respectively. The McNemar χ 2 test showed no significant difference between the two methods ( P>0.05), and the Kappa consistency test showed good consistency between the two methods ( Kappa=0.9, P<0.05). Conclusion:A nucleic acid mass spectrometry detection system suitable for clinical candida detection was successfully constructed, and the method validation results were consistent with the clinical blood culture.

Geotricosis: fungemia en paciente con leucemia linfoblástica aguda / Geotrichosis: fungemia in a patient with acute lymphoblastic leukemia

La fungemia por Geotrichum spp. es poco frecuente y altamente letal. En el Instituto Nacional de Cancerología de Bogotá solo se han reportado dos casos: uno entre el 2001 y el 2007, y el otro entre el 2012 y el 2018. Este tipo de infección es más común en pacientes con algún grado de compromiso del sistema inmunitario, por lo que puede presentarse en pacientes con neoplasias hematológicas malignas. Se presenta el caso de un hombre de 27 años con recaída de leucemia linfoblástica aguda, que ingresó con poliartralgias de cinco días de duración. También cursaba con neutropenia febril, celulitis sin abscesos y bacteriemia por Staphylococcus aureus resistente a la meticilina para lo cual recibió terapia con oxacilina y cefepime. Sin embargo, persistía la neutropenia febril por lo que se sospechó una infección fúngica invasora. Se tomó un nuevo set de hemocultivos y se inició tratamiento antifúngico. En los hemocultivos se identificaron artroconidias y mediante espectrometría de masas por láser de matriz asistida de ionización-desorción se confirmó la presencia de Geotrichum spp. Se ajustó el tratamiento antifúngico con deoxicolato de anfotericina B por 14 días y voriconazol por cuatro semanas. Luego de una estancia prolongada se le dio de alta. Aunque la incidencia de la fungemia por Geotrichum spp. es baja, en pacientes con neoplasias hematológicas malignas debe considerarse en el contexto de una neutropenia febril que es persistente a pesar del tratamiento antimicrobiano de amplio espectro. La identificación de los agentes causantes de fungemias con herramientas de proteómica, como la espectrometría de masas mencionada, permite ajustar el tratamiento dirigido y reducir las complicaciones, la estancia hospitalaria y la mortalidad.

Fungemia caused by Geotrichum spp. is rare and highly lethal. The Instituto Nacional de Cancerología in Bogotá reported just two cases: one in the period 2001-2007 and the other in 2012-2018. This type of infection is more common in any kind of immunocompromised patients, so it can occur in those with hematological malignancies. Here we present the case of a 27-year-old man, diagnosed with acute lymphoblastic leukemia in relapse and admitted with polyarthralgia for five days, febrile neutropenia, non- abscessed cellulitis, and bacteremia due to methicillin-sensitive Staphylococcus aureus. The patient received therapy with oxacillin and cefepime, but the febrile neutropenia persisted. A new set of blood cultures was taken, and antifungal treatment was started because of the suspicion of invasive fungal infection. Arthroconidia were identified in blood cultures and Geotrichum spp. was confirmed using matrix-assisted laser desorption-ionization mass spectrometry. The antifungal treatment was adjusted with amphotericin B deoxycholate for 14 days and voriconazole for four weeks, and after a prolonged stay, the patient was discharged. Although the incidence of fungemia caused by Geotrichum spp. is low, it must be considered in patients with hematological malignancies and persistent febrile neutropenia despite the broadspectrum antimicrobial treatment. The confirmation of fungemia causing agents, with proteomic tools such as the mentioned mass spectrometry, allows treatment adjustment and decreases complications, hospital stay, and mortality.

Fusariosis en pacientes con cáncer: serie de 13 casos y revisión de la literatura / Fusariosis in cancer patients: 13 case series report and literature review

La fusariosis es una micosis oportunista producida por Fusarium spp. Su presentación clínica depende del estado inmunológico del huésped, especialmente, el de aquellos con enfermedades hematooncológicas, cuyas manifestaciones varían desde formas localizadas hasta infección fúngica invasora. El cultivo de piel o de sangre permite orientar el tratamiento antifúngico combinado con anfotericina B y voriconazol. Se presentan 13 casos de pacientes con cáncer en un periodo de once años que desarrollaron fusariosis diseminada; asimismo, se hizo con una revisión extensa de la literatura. En esta serie de casos, la mortalidad fue del 61,5 % (8/13), a pesar del uso del antifúngico. De los 13 pacientes, 11 tenían neoplasia hematológica y 2 neoplasia sólida. El factor de riesgo más importante fue la neutropenia profunda. El compromiso de la piel y los hemocultivos positivos facilitaron la prescripción del tratamiento combinado en la mayoría de los casos. La neutropenia febril persistente asociada a lesiones cutáneas, la onicomicosis, los nódulos o las masas pulmonares permitieron sospechar una infección fúngica invasora por Fusarium spp. El objetivo de la presentación de esta serie de casos es recordar el diagnóstico de fusariosis a la comunidad médica en contacto con pacientes oncológicos, con neutropenia febril profunda y persistentes.

The fusariosis is an opportunistic mycosis caused by Fusarium spp. Its clinical presentation depends on the immunological status of the host, especially in patients with hemato-oncological diseases, whose manifestations vary from localized to invasive fungal infections. Skin or blood culture helps to guide combined antifungal treatment with amphotericin B and voriconazole. Here, we present 13 cases in a period of eleven years of patients with cancer who developed disseminated fusariosis and their outcomes, together with a review of the related literature. In this series of cases, mortality was 61.5 % (8/13), despite the use of the antifungal. Out of the 13 cases, 11 had hematological neoplasia and 2 solid neoplasia. The most determinant risk factor was profound neutropenia. Skin involvement and positive blood cultures in most cases allowed combined treatment prescription. Persistent febrile neutropenia associated with skin lesions, onychomycosis, nodules, or lung masses lead to suspicion of Fusarium spp. fungal invasive infection. The aim of this series of cases is to remind healthcare professionals that oncological patients with deep and persistent febrile neutropenia can develop fusariosis.

A peculiar case of onychomycosis caused by Cladosporium halotolerans

ABSTRACT A 49-year-old patient with changes in the nails of the hallux for 10 years was diagnosed with onychomycosis. The identity of the causative agent was confirmed as Cladosporium halotolerans from the Cladosporium sphaerospermum species complex using molecular techniques. MALDI-TOF identified the agent as C. sphaerospermum complex species. Overall, species such as onychomycosis agents should attract special attention to avoid mistakes in the identification process while considering a probable contaminant as responsible for the disease. These species deserve attention since there are rare descriptions of them as causes of onychomycosis. It is important to recognize them as causes of disease and not just as a probable contaminant.

Analytical methods for assessing changes induced by gamma exposure in an animal model

SUMMARY OBJECTIVE: Ionizing radiation can cause radio-induced changes in the cellular metabolome due to the breakdown of DNA bonds. Our goal was to find the early tissue response to radiation exposure supported by distinct analytical methods. METHODS: Histological analyses were performed on the organs extracted from rats to search for microscopic changes. The histological slides stained with hematoxyline-eosin (HE) were analyzed in magnification (40x). Subsequently, the tissues were subjected to mass spectrometry that allowed molecular analysis and DESI-MSI that generated the molecular image of lipids, assessing changes in intensities, especially in the brain. RESULTS: The histological analysis found nonspecific inflammatory changes; no areas of fibrosis, necrosis, or apoptosis were identified, suggesting non-morphological tissue alterations. However, the DESI-MSI images of brain lipids allowed the observation of many radio-induced changes in the lipid's intensities. CONCLUSIONS: No early radio induced histological or mass weight changes in the radiation exposed rats could be observed at 5 Gy. However, early changes in the molecular level were observed in the DESI-MSI images of the brain lipids. The DESI-MSI method proved to be efficient and relevant, allowing a regional molecular analysis of the tissues, expanding a new field of study that is still in its infancy: radiometabolomics.

RESUMO OBJETIVO: Radiação ionizante pode causar alterações no metaboloma celular devido à quebra de ligações no DNA. O objetivo deste trabalho foi evidenciar a resposta aguda tecidual induzida pela exposição da radiação ionizante. MÉTODOS: Análises histológicas foram realizadas nos órgãos extraídos de ratos para análise de alterações microscópicas. As lâminas histológicas coradas com hematoxilina eosina (HE) foram analisadas em aumento (40x). Posteriormente, os tecidos foram submetidos a espectrometria de massa, que permitiu análise molecular e o Desi-MSI que gerou imagem molecular de lipídios, identificando alterações na intensidade, principalmente no cérebro. RESULTADOS: As análises histológicas encontraram alterações inflamatórias inespecíficas, nem áreas de fibrose, necrose ou apoptose, sugerindo ausência de alterações morfológicas. As imagens de lipídios cerebrais obtidas por Desi-MSI permitiram observar as inúmeras alterações na intensidade nas seções teciduais do encéfalo. CONCLUSÕES: Alterações agudas radioinduzidas de massa do órgão e histológicas nos órgãos dos ratos expostos não puderam ser observadas a 5 Gy. Entretanto, mudanças em nível molecular foram observadas nas imagens de Desi-MSI dos lipídios cerebrais. O método Desi-MSI mostrou-se eficiente e relevante, permitindo a análise molecular regi-onal dos tecidos no SNC, expandindo um novo campo de estudo que ainda está em sua infância: a radiometaboloma.

The development and verification of "Chinese Pathogenic Mycobacteria Mass Spectrometry Database" / 中华检验医学杂志

Objective@#To establish the domestic matrix assisted laser desorption/ionisation time of flight mass spectrometry database for identification of clinical mycobacteria and evaluate its accuracy with foreign counterpart. @*Methods@#The establishment of "Chinese Pathogenic Mycobacteria Mass Spectrometry Database" : nineteen American type culture collection strains from 19 species and 183 "standardized" isolates from 42 species were selected and extracted by modified ultrasonic extraction method for spectral acquisition and database establishment based on microTyper MS. Each extract was dropped onto 12 spots and tested twice to generate 24 spectrum, then at least 20 qualified spectrum according to the standard were selected. Subsequently they were composed into one main spectra (MSP) by setting peak number maximum, peak frequency minimum and mass tolerance. Verification of database: Totally 305 mycobacteria from different regions were used for comparison of accuracy and spectral features between microTyper MS based on domestic database and imported MALDI TOF MS base on Mycobacteria Library 3.0 database. @*Results@#The database composed of 202 stains from 42 species was constructed, with an average of 4.8 in each species. The top ten were M. Kansasii(16), M. intracellulare(16), M. gordonae(16), M. fortuitum(16), M. avium(16), M. abscessus(16), M. tuberculosis(15), M. marseillense(11), M. arupense(10), M. yongongens(8). A total of 305 isolates were confirmed belonging to 22 species by sequencing. The accuracy based on this database was 99.67% (304/305), which was better than the Mycobacteria Library 3.0 database (χ2=4.06, P<0.05). @*Conclusion@#The construction of the "Chinese Pathogenic Mycobacteria Mass Spectrometry Database" meets the requirement of routine clinical application and was more accurate than its counterpart in terms of domestic comment strains.(Chin J Lab Med, 2018, 41: 519-526)

The challenge of MALDI-TOF MS technique in clinical microbiological diagnosis and application / 中华检验医学杂志

MALDI-TOF MS is a revolutionary and innovative technologyin clinical microbiological diagnosis. Due to its advantages of speed, specificity and ease of operation, MALDI-TOF MS has been rapidly accepted and approved by clinical laboratory. However, many challenges appeared when applied in clinical application. For example, sample preparation needs to be further optimized. Identification techniques have limitations. The quality improvement of database and the diversity of microbial species are still under discussion.The application of antimicrobial susceptibility testing is still controversial.The way ofrare identification resultstransmitting into clinical treatment is still being explored. But the application of MALDI-TOF MS in clinical microbiological diagnosis still needs to be improved.(Chin J Lab Med, 2018, 41: 559-562)

Method selection for pretreatment in direct identification of pathogen in positive blood culture by MALDI-TOF MS / 中华检验医学杂志

Bloodstream infection is one of the leading causes of death worldwide. Rapid determination of the primary pathogen is crucial for diagnosis and antibiotic therapy of bacteremia. The application of Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) was a major breakthrough in microbiology. This technology is simple, rapid, economical and accurate, which has been introduced into the microbiology laboratory formicroorganism identificationwidely. Recently, MALDI-TOF MS was combined with extraction methods for direct pathogens identificationfrom positive blood cultures. The methods of pathogensextraction from positive blood cultures are crucial for the accuracy of identification. And developing a standard extraction protocolhas become a hot spot of research in recent years. (Chin J Lab Med, 2018, 41: 563-566)

Rapid detection of rmpA2-carrying hypervirulent Klebsiella pneumoniae by MALDI-TOF MS / 中华检验医学杂志

Objective@#To evaluate the ability of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) in identifying the rmpA2-carrying hypervirulentKlebsiella pneumoniae.@*Methods@#A total of 57nonduplicateKlebsiella pneumoniae isolates were collected from the Second Affiliated Hospital of Zhejiang University and Henan Provincial People′s Hospital. Virulence gene rmpA2 and capsule K serotype-specific genes were detected by PCR, multilocus sequence typing (MLST) was performed for molecular typing, and string test was conducted to identify the hypermucoviscous phenotype. The ClinProTools software was used for peak analysis. Four standard algorithms, including support vector machine (SVM), genetic algorithm (GA), supervised neural network (SNN), and quick classifier (QC), were tested for their power to differentiate between rmpA2-positive and rmpA2-negative strains.@*Results@#Among the 57 Klebsiella pneumoniae isolates, 28 isolates belonged to sequence type (ST) 11 and carried the virulence gene rmpA2, of which 5 isolates were positive for string test; while the other 29 isolates were not detected rmpA2, and MLST divided them into five STs including ST11 (n=23), ST15 (n=3), ST1 (n=1), ST76 (n=1), and ST473 (n=1). The results of four standard algorithms were similar, while the sensitivity and specificity of SVM was the highest at 93.23% and 100% respectively. Analysis results of ClinProTools software suggested that the specific peaks for differentiating the rmpA2-positive and rmpA2-negative strains were 7 168.9 and 7 280.76, however, the peak intensity of themwere variant.@*Conclusion@#The sensitivity and specificity ofMALDI-TOF MS for rapid identification of rmpA2-carrying hypervirulentKlebsiella pneumoniae werehigher than 90% and there was a difference on the peak intensity of two specific peaks, which needs further study.(Chin J Lab Med, 2018, 41: 571-675)

Application of MALDI-TOF MS in identification of clinical Aspergillus / 中华检验医学杂志

Objective@#To discuss the application of matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) in the identification of Aspergillus and evaluate its performance.@*Methods@#the clinical isolates of Aspergillus collected from May 2017 to March 2018 in PLA General Hospital were identified by VITEK MS V3.0 and the results were analyzed. The ITS sequencing resultswere used as the gold standard.@*Results@#It identified 9 Aspergillus species (including 12 Aspergillus species in total) through the V3.0 database, accounting for 86.24% of the total clinical isolates. The identification rate by VITEK MS was 91.49% with 16.51% was not identified. The coincidence rate of genus was 93.62%, of which only two Aspergillus versicolor were identified to the level of the genus. According to the confidence level analysis, 88.30% of the strains obtained more than 99% of the identification rate. 13.83% of the strains did not have the identification results for the first time, with the error rate of 3.19%. After secondary extractions, the percentage of unidentified strain was reduced to 6.38%, and the identification error rate was reduced to 2.13%. Combined with traditional identification and VITEK MS identification, the correct rate of strains identification was 98.94% on genus level, and was 93.62% on species level. The influence of other fungi on Aspergillus identification was 0%.@*Conclusion@#As a powerful supplement to the traditional identification method, MALDI-TOF MS showed a lot of convenience when applied in the identification of Aspergillus, which improves the identification accuracy and the identification ability for fungi in laboratory.(Chin J Lab Med, 2018, 41: 577-582)

Homology analysis of Carbapenems-resistant klebsiella pneumoniae by MALDI-TOF MS / 中华检验医学杂志

Objective@#To evaluate the ability of matrix-assisted laser desorption/ionization-time of flight mass spectrometry(MALDI-TOF MS) in the homology analysis of Carbapenems-resistant klebsiella pneumonia.@*Methods@#Twenty-one non-duplicated strains of Carbapenems-resistant klebsiella pneumoniae were isolated from Shandong Provincial Hospital affiliated to Shandong University during April 2011 and October 2013 in this study. Twenty isolates were from neonatal unit and one from cardiac surgery. The homology analysis of Carbapenems-resistant klebsiella pneumoniae was performed with pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST) and MALDI-TOF MS respectively.@*Results@#The result of PFGE was consistent with MLST. The twenty-one CRKPN strains were divided into three groups by MALDI-TOF MS according to their relationship, 18 of them belonged to II group, and the homology was higher than 75%. From the analysis of protein mass spectra of 18 strains, the protein peaks were roughly the same. Thus, it was concluded that their relationship was close, and the results were basically consistent with the results of PFGE and MLST. The H13 strain with low homology (<60%) was different from the above strains, especially in the molecular weight 4365, 5381 and 6289.The PFGE analysis showed that the homology between H13 and other strains was 61%, and the MLST classification result was ST54.@*Conclusions@#MALDI-TOF MS can be used to identify CRKPN accurately and analyze its homology analysis more conveniently than other methods in clinical laboratory. MALDI-TOF MS has the potential to be used as an easy and rapid epidemiology typing tool for nosocomial infection investigation caused by drug-resistant bacteria.(Chin J Lab Med, 2018, 41: 589-595)

Detection of 16S rRNA gene and biological characteristics of Mycobacterium abscessus / 中华皮肤科杂志

Objective To identify a clinical isolate of Mycobacterium abscessus.Methods A pus sample was collected from a patient with suspected nontuberculous mycobacterial infection who visited the Affiliated Hospital of Weifang Medical University on December 18,2017,and was subjected to bacterial culture,Gram staining and acid-fast staining.Drug sensitivity test was conducted by the proportion method.The genome DNA of the strain was extracted and amplified by PCR with the universal primer of 16S rRNA.The PCR products were sequenced after collection and purification,and were compared with the known sequence of Mycobacterium abscessus in GenBank database.The isolate was identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS).Results The clinical isolate was identified as Mycobacterium abscessus both by MALDI-TOF MS and 16S rRNA gene sequencing.The drug sensitivity test showed that the strain was sensitive to amikacin,moxifloxacin,levofloxacin,but was resistant to streptomycin,isoniazid,rifampicin,ethambutol,ofloxacin,kanamycin,capreomycin,aminosalicylic acid,protionamide and rifabutin.The patient was diagnosed with subcutaneous soft tissue infection in the left knee joint.According to the results of drug sensitivity test,the patient was treated with amikacin and levofloxacin,and her condition was improved after treatment.Conclusion The 16S rRNA gene detection and MALDI-TOF MS both can be applied in the identification of Mycobacterium abscessus.

Evaluation of matrix-assisted laser desorption ionization-time-of-flight mass spectrometry to differentiate Candida / 中华检验医学杂志

Objective To evaluate the efficiency of matrix assisted laser analytical ionization time of flight mass spectrometry(MALDI-TOF-MS)for identification of Candida species which caused vulvovaginal candidiasis(VVC).Methods Candida strains from VVC were first identified by PCR amplification of the ITS regions and transposable intron of DNA and sequencing analysis.MALDI-TOF-MS wasfurther performed to identify the strainsconfirmedby molecular methods, and at the same time the MALDI-TOF-MS identification database of C.albicans complex was set up.Results In total, 324 Candida strains were identifiedby molecular methods from VVC samples,which encompassed20 different yeast species, including C.albicans,C.africana,C.dubliniesis, C.glabrata, C.bracarensis, C.nivariensis, C.guilliermondii, C.lusitaniae,C.krusei,C.kefyr,C.parapsilosis,C.metapsilosis,C.tropicalis,Kodamaea ohmeri,C. fabianii, Rhodotorula mucilaginosa, Saccharomyces cerevisiae, and Trichosporon asahii.314of all 324 Candida strains were correctly identified by MALDI-TOF-MS.3 C.albicans,1 C.africana,1 C.glabrata, 2 C.metapsilosis,1 C.guilliermondii and 1 Saccharomyces cerevisiae were incorrectly identified, while 1 Torulaspora pretoriensiscannot identified.The accuracy ofidentification was 96.91 %(314/324).97.95%(191/195)of Candida strains, including 153(98.08%)C.albicans, 37(97.37%)C.africanaand 1 (100%)C.dubliniesis, can be correctly identifiedby the newbuiltC.albicans complex database. Conclusion MALDI-TOF-MS is proved to be a rapid and reliable method for identification of Candida strains from VVC,which also has advantages of identification of Candida complex.(Chin J Lab Med,2018, 41:296-299)

Identification of Chromobacterium violaceum by MALDI-TOF mass spectrometry in blood culture

Report of Chromobacterium violaceum isolation from blood culture. Identification by MALDI-TOF mass spectrometry. Relevant report due to the site affected, infection severity, and importance of correct and rapid identification for a successful treatment and lower risk of morbidity and mortality. (AU)

Evaluation of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry system ;Clin-TOF-Ⅱ MS in identification of gram-negative bacteria / 中华检验医学杂志

Objective To evaluate the performance of domestic matrix-assisted laser desorption/ionization time-of-flight mass spectrometry system Clin-TOF-Ⅱ MS with BioExplorer V2.3 database ( Clin-TOF MS system) on gram-negative bacteria identification.Methods This was a methodological comparison study.A total of 1 025 gram-negative strains of 32 genus, 56 species or species complex were included in this study from 1999 to 2000 and 2014 to 2016 in Peking Union Medical College Hospital.The Bruker Biotyper MS system ( Bruker MS system ) , Bruker Autoflex Speed with Biotyper v 3.1 database were used as control.Identification by both MALDI-TOF MS systems were parallel conducted by direct smear method.The 16S rDNA sequencing based identification was performed when either MALDI-TOF MS system gave“unbelievable result” or results from two systems were not consistent.Results Amongst the isolates studied, 98.05% (1 005/1 025) was correctly identified to species or species complex level by Clin-TOF MS system.Comparatively, 99.22%(1 017/1 025) was correctly identified by Bruker MS system.There were 17 isolates just identified to genus level and 2 isolates were “no identification” by Clin-TOF MS system, meanwhile 1 Pseudomonas monteilii misidentified as P.putida.There were only two 2 isolates identified to genus level and 3 isolates were“no identification” by Bruker MS system.But it misidentified all 3 Aeromonas hydrophila (2 isolates as A.caviae and 1 isolate as A.media).It′s noted that both MS systems identified 1 Chryseobacterium gleum and 1 C. bernardetii to genus level.Conclusion The identification capability of domestic Clin-TOF MS system was good on gram-negative bacteria.

Application of matrix-assisted laser desorption/ionization-time of flight mass spectrometry for the ;identification of Helicobacter pylori / 中华检验医学杂志

Objective To optimize the pre-treatment method before detecting Helicobacter pylori ( H.pylori ) by matrix-assisted laser desorption ionization/time-of-flight mass spectrometry ( MALDI-TOF MS) and evaluate the ability of the Superspectra by MALDI-TOF MS for identifying clinical isolated H.pylori strains.Methods H.pylori were isolated from 469 biopsy samples of gastric mucosa collected from January 2015 to July 2016 in Huadong Hospital affiliated to Fudan University , 16 s rRNA sequencing were then performed to validate the strains.Then 91 isolated H.pylori strains were used for the subsequent MALDI-TOF analysis.The effect of pre-treatment of 50%isopropanol, formic acid and acetonitrile (1∶1), 70%formic acid were compared before H.pylori detecting by MALDI-TOF MS.40 out of 91 clinical H.pylori strains were detected by MALDI-TOF MS and the spectra were randomly assigned to 4 groups including 5, 10, 20, 30 spectra, each group had 3 repeats.Then 4 groups with different amount of spectra were used for creating Superspectra with SARAMIS Premium software , respectively.The remaining 51 H.pylori strains including 306 spectra were used for validating the identification rate of the Superspectra.Results With the use of 70%formic acid, the greater number of ion signals and higher relative intensity of the main peaks were observed than other pre-treatment reagents.The identification rate of Superspectra created by 30 strains group was the highest ( 90.2%).Among the 306 spectra, 46.1% of them achieved highly reliable identification , 22.2% achieved lower degree of reliable identification , and 31.7% of them achieved “no identification”.Conclusions The study optimized the pre-treatment method before H.pylori detecting by MALDI-TOF MS.The Superspectra was created with the good ability to rapidly identify clinical isolated H.pylori strains.

Drug resistance and nosocomial infection analysis of 1521 strains MDR / 中国医师杂志

Objective To investigate the situation of drug resistance and nosocomial infection of multi-drug resistant bacteria (MDR),guidance for clinical rational use of antibiotics.Methods A total of 1521 strains of MDR was isolated from January 2015 to December in Beijing Tongren Hospital,using matrixassisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) identification of bacteria,VITEK-2 Compact and Kirby Bauer (KB) method for drug sensitivity test.Results In 1 521 strains of MDR,Acinetobacter Baumanii were 589 strains (38.7％),nosocomial infection rate were 16.6％;350 strains of Escherichia coli (23.0％),nosocomial infection rate were 9.0％;249 strains of Staphylococcus aureus (16.4％),nosocomial infection rate were 2.7％;171 strains of Klebsiella pneumoniae (11.2％),nosocomial infection rate were 14.3％;150 strains of pseudomonas aeruginosa (9.9％),nosocomial infection rate were 64.7％;12 strains of Enterococcus faecium (0.8％),nosocomial infection rate were 16.7％.MDR Acinetobacter Baumanii,MDR Pseudomonas aeruginosa,extended-spectrumβ-lactamase (ESBL) + Escherichia coli and ESBL + Klebsiella pneumoniae resistance rate to Imipenem were 100％,91.5％,0.6％ and 55.6％.Conclusions MDR pseudomonas aeruginosa (MDR-PAE),MDR acinetobacter baumanii (MDR-AB) and ESBL + Klebsiella pneumoniae were highly resistant,and the nosocomial infection rate were higher.

Application of MALDI-TOF mass spectrometry in bacterial typing / 中华检验医学杂志

As a rapid, accurate and high throughput bacterial identification technique, matrix-assisted laser desorption ionization time of flight mass spectrometry(MALDI-TOF MS)has been gradually applied to clinical microbiological laboratories.However, the application of MALDI-TOF MS is far beyond the identification of bacteria.It also has broad application prospect in bacterial typing.The MALDI-TOF MS based typing method is simple, rapid, low-cost and high throughput, which can play an important role in nosocomial infections surveillance.

Correlation between prostacyclin synthase gene rs5602 polymorphism and ischemia stroke in Chinese Han population / 国际脑血管病杂志

Objective To investigate the correlation between prostacyclin synthase (prostaglandin I2 synthase, PGIS) gene rs5602 single nucleotide polymorphism and ischemia stroke in Chinese Han population. Methods The patients with ischemia stroke and healthy controls in Chinese Han population were enroled. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF MS) was used to detect the rs5602 polymorphism. Results A total of 297 patients with ischemic stroke (male 177 and female 120) and 291 healthy controls (male 165, female 126) over the same period were enroled. The frequencies of TT genotype (31. 1% vs. 43. 6% ; χ2 = 5. 773, P = 0. 016) and T alele (56. 8% vs. 65. 8% ; χ2 = 5. 793, P = 0. 016) in the male patients with ischemic stroke were significantly lower than those in the male healthy controls. Multivariate logistic regression analysis showed that the rs5602 TT genotype was a protective factor for ischemic stroke in male (odds ratio 0. 260, 95% confidence interval 0. 118-0. 570; P = 0. 001). Conclusions PGIS gene rs5602 polymorphism is associated with ischemic stroke in male in Chinese Han population.

Identification of m/z characteristics of Staphylococcus aureus in agr and sigB regulatory system using MALDI-TOF-MS / 中华检验医学杂志

Objective The expression of agr and sigB regulation system in Staphylococcus aureus with different infection types were assessed by analyzing the characteristics of m /z value generated by MALDI-TOF-MS.Methods A total of 50 isolates with specific genotypes were collected from Tianjin First Center Hospital during Jun 2013 to Feb 2014 for retrospective study .The pattern profiles of these isolates were obtained by MALDI-TOF-MS with RUO model, and the m/z value was also analysed to evaluate the expression the agr and sigB regulation system .The phylogenetic tree based on mass spectrum peak feature was constructed using SARAMIS software .Results A total of 50 strains of Staphylococcus aureus were divided into two groups: acute infection and chronic persistent and recurrent infection .The expression of delta toxin in acute infection and in chronic infection was 99.2 ±4.1 and 60.5 ±10.1 ( t =16.83, P<0.05), respectively.The regulation of stress proteins of sigB system was enhanced in chronic persistent and recurrent infections , and the expression intensities of SAS 030, SAS049 and SA0772 were 27.1 ±14.7, 54.8 ±21.5 and 51.6 ±19.2, respectively; while in acute infections , those were 4.9 ±1.9, 12.4 ±2.8 and 15.7 ±6.9, respectively.The t values between the two groups were -6.88 (P<0.05),-8.98 (P<0.05) and -1.87 (P<0.05), respecitively.The expression of phenol-soluble modulins (PSMs) was inconsistent , and the relative strength of PSMα3 was 100%in the colony variants small strains .Conclusions Different types of the Staphylococcus aureus infections could be evaluated through the assessment of the agr and sigB regulation system .The m/z value obtained by MALDI-TOF mass spectrometry is a marker for the expression of agr and sigB regulation system .The application of this technology needs further development .