Chinese Journal of Mycology

Evaluation of the MALDI-TOF MS in-house database in identification of clinical filamentous fungi isolates

LI Ying, HUANG Jingjing, LIU Wenjing, WANG Peichang, XU Yingchun

2021, 16(6): 361-366.

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Objective To evaluate the MALDI-TOF MS in-house database in identification of clinical filamentous fungi isolates. Methods Forty-one filamentous fungi isolates genetically confirmed by molecular sequencing method were used as the representative strains to construct the MALDI-TOF MS in-house database. The mass spectra profiles of the representative strains from young stage and mature stage colonies were created respectively according to the standard extraction procedure into the in-house database. The MALDI-TOF MS in-house database was challenged subsequently to identify other 236 clinical filamentous fungi isolates. Results The MALDI-TOF MS in-house database included 82 mass spectra profiles of 41 representative strains from 10 genera and 25 species. The species level identification rate of the 236 evaluated isolates could be increased from 29.2% (69/236) with the Bruker commercial library to 67.5% (159/236) with the MALDI-TOF MS in-house database; the highest species level identification rate was 76.3% (180/236) after combining the Bruker commercial library with the in-house database. There was no advantage of the MALDI-TOF MS in-house database in identification of common Aspergillus isolates than the morphological method. While for the cryptic species of Aspergillus and non-Aspergillus filemantous fungi, the species level identification rate was 61.8% (34/55) by the MALDI-TOF MS in-house database which significantly superior than the morphological method rate of 16.4% (9/55). Conclusions The in-house database could improve the performance of MALDI-TOF MS in identification of filamentous fungi isolates, especially for the less encountered species which were difficult to be identified with the conventional morphological method.

The value of quantitative PCR detection combined with G test and GM test in the early diagnosis of invasive fungal infections

SHANG Yuanyuan, LI Kexin, MA Chunmei, LI Shasha, HU Rongying, YANG Wenjun

2021, 16(6): 367-372.

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Objective To explore the value of RT-PCR (RTFQ-PCR) detection combined with G test and GM test in the early diagnosis of invasive fungal infection. Method From April 2014 to October 2015, 60 cases at high risk of IFI from several departments including ICU of our hospital were enrolled. Fungal culture of blood, phlegm and alveolar lavage tissue samples, plasma (1,3) -β-D-glucan assay (G test), galactomannan antigen assay (GM test) and fluorescence quantitative RTFQ-PCR were performed. The ROC curve analysis was conducted to evaluate the diagnostic value of fluorescence quantitative RTFQ-PCR for IFI. Results G test positive rates of IFI, clinical diagnostic, suspected and excluded groups were 100%, 70.37%, 75.00% and 54.55% respectively; GM detection positive rates were 66.67%, 70.37%, 62.50% and 45.45% respectively; The positive rates of RTFQ-PCR were 100%, 81.48%, 87.50% and 22.73%, respectively. Results of G test: sensitivity was 81.58%, specificity 59.09%, positive predictive value 77.50%, negative predictive value 65.00%, and coincidence was 73.33%. The sensitivity, specificity, positive predictive value and negative predictive value of GM test were 76.32%, 68.18%, 80.56%, 62.50% and 73.33%, respectively. The sensitivity, specificity, positive predictive value, negative predictive value and conformity of RTFQ-PCR were 84.21%, 77.27%, 86.49%, 73.91% and 73.91% respectively. The sensitivity, specificity, positive predictive value and negative predictive value of RTFQ-PCR+G+GM combined detection were 55.26%, 95.45%, 95.45%, 55.26% and 70.00% respectively. Conclusion G test, GM test and RTFQ-PCR test showed high clinical application value in IFI diagnosis (all P < 0.05), but G test and GM test had high false positive rates in IFI diagnosis, so RTFQ-PCR test was recommended in single detection, and RTFQ-PCR+G+GM combined detection could significantly improve the accuracy of IFI clinical diagnosis.

Analysis of functional differentiation between Cyp51A and Cyp51B of Aspergillus fumigatus

FANG Lingxu, LIANG Hai, WANG Pengyuan, LU Zhongyi, CHEN Fangyan, HAN Li

2021, 16(6): 373-378.

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Objective The functional differentiation of Aspergillus fumigatus Cyp51A and Cyp51B was characterized in this study. Method The phylogenetic tree of Cyp51A and Cyp51B was constructed by IQ-tree. The Aspergillus fumigatus Δcyp51A and Δcyp51B mutants were constructed by homologous recombination technology, respectively. The high temperature tolerance and voriconazole susceptibility of both Δcyp51A and Δcyp51B mutants were determined. Moreover, the virulence of Δcyp51A and Δcyp51B mutants was investigated in the Galleria mellonella infection model. Result Phylogenetic analysis revealed that the Cyp51Bs formed a cluster that was separated from Cyp51As. The Δcyp51B mutant showed reduced tolerance to 50 °C when compared to the Δcyp51A and wild-type strain. The Δcyp51A mutant manifested significantly reduced tolerance to voriconazole when compared to that in Δcyp51B mutant. Additionally, there was no statistically significant difference among the Δcyp51A mutant, Δcyp51B mutant, and the wild-type strain. Conclusion The Cyp51A held different functional roles in high temperature tolerance and azole susceptibility of A. fumigatus when compared with Cyp51B.

Diagnostic value of serum cryptococcal capsular polysaccharide antigen detection and interventional procedures in pulmonary cryptococcosis

YUAN Cheng, DING Ming

2021, 16(6): 379-383.

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Objective To evaluate the diagnostic value of pulmonary cryptococcosis (PC) for serum cryptococcal capsule polysaccharide antigen (CrAg) detection, ultrasound-guided transbronchial lung biopsy (EBUS-TBLB) and CT-guided percutaneous lung biopsy, and to analyze the affecting factors. Methods From January 2015 to December 2020, 41 patients diagnosed pathologically with PC in Southeast University Zhongda Hospital were analyzed retrospectively;serum CrAg detection was performed in all patients. Results Among the 41 patients, 32 patients underwent EBUS-TBLB and 16 were confirmed PC, the sensitivity was 50%(16/32), 23 patients underwent CT-guided percutaneous lung biopsy and 22 were diagnosed, with the sensitivity 95.7%(22/23), while 3 were comfirmed by surgery; 29 cases were positive for CrAg detection in the 41patients (sensitivity of 70.7%), while the sensitivity could be increased to 96.9% combined with EBUS-TBLB; Imaging features had no significant effect in the diagnosis of PC for EBUS-TBLB. Patients had wider lesions of the lung and had immune suppression, whose sensitivity of serum CrAg detection in PC was higher. Conclusions CT guided percutaneous lung biopsy has more advantages in the diagnosis of PC; combined with EBUS-TBLB and serum CrAg detection can significantly improve the sensitivity , and serum CrAg detection has a good sensitivity when the range of lung lesions were wide and patients were in immunosuppression.

Analysis of microflora distribution, drug susceptibility and risk factors of fungal infection in patients with urolithiasis

YE Junbing, YE Lihong, HE Jiansong, LI Wangjian, LI Feng, WAN Junyan

2021, 16(6): 384-387,402.

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Objective The characteristics of the distribution of pathogen, drug susceptibility and risk factors of fungal infection in urolithiasis patients were analyzed to provide evidence for actively prevention and rational drug use. Methods From January 2017 to December 2019, 480 patients with urologic calculus and suspected infection diagnosed in the urology department of our hospital were selected. According to the results of urine culture, 59 patients with fungal infection were included in the observation group, 421 patients with non-fungal infection were included in the control group, SPSS 22.0 software was used for statistical analysis of the characteristics of the distribution of pathogenic fungi, drug susceptibility and risk factors of patients with fungal infection. Results ①Fungal distribution: among the 59 cases of fungal infection, the candida tropicalis infections was the most common, accounting for 20 cases (33.9%). ②Drug sensitivity characteristics: The resistance rates of fungi to amphotericin B, 5-fluorocytosine, voriconazole, fluconazole and itraconazole were 0, 1.7%, 16.9%, 22.0% and 23.7%, respectively. ③Risk factors: Multivariate Logistic regression analysis showed that diabetes, hypoalbuminemia and abnormal renal function were independent risk factors for fungal infection (P<0.05). Conclusions The most common pathogenic fungus in urolithiasis patients in our hospital was candida tropicalis. Doctors should take measures to prevent fungal infection according to the risk factors and use antibiotics rationally.

Allele specific PCR for rapid detection of common gene mutations associated with the resistance of Aspergillus fumigatus

DENG Yuchen, FANG Wenjie, DENG Shuwen, CHEN Xianzhen, ZHANG Yaru, FENG Zhenyi, LING Liyan, PAN Weihua, LIAO Wanqing

2021, 16(6): 388-391.

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Objective To establish an allele specific PCR detection system for common resistance mutation genes L98H/TR34 of Aspergillus fumigatus and determine its resistance to azoles quickly and accurately. Methods Allele specific PCR method was used to simultaneously detect azole-resistant mutation genes L98H/TR34, and specificity and sensitivity of the system was evaluated. Results The real time PCR dissolution curves of all resistance gene positive Aspergillus fumigatus showed double peaks, but no mutation sites were detected in non-resistant Aspergillus fumigatus. Conclusion Allele-specific PCR can quickly detect common resistance mutant genes L98H/TR34 of Aspergillus fumigatus, with high specificity and sensitivity, simple operation and low price.

Analysis of related factors of mixed Candida/bacterial bloodstream infections in neonates

XIE Zhaoyun, LI Wenhua, YANG Zhongling

2021, 16(6): 392-396.

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Objective To investigate the related factors of mixed Candida/bacterial bloodstream infections in children. Methods The clinical data of 225 children with Candida bloodstream infection from March 2013 to June 2020 were reviewed. The related factors of mixed Candida/bacterial bloodstream infection were analyzed by univariate and multivariate analysis. Results The incidence of mixed Candida/bacterial bloodstream infection was 29.33%. Univariate analysis showed that gestational age (<37 weeks), birth weight (<2 500 g), age of onset (<7 D), amniotic fluid pollution, intrauterine distress, apagar score (<7 points), type of infection (hospital infection), length of stay in NICU (≥7 days), premature rupture of membranes, hospitalization time (≥14 days), invasive treatment, AP 14 factors such as ache Ⅱ score (≥15 points), the number of antibiotics replaced (≥3 kinds), serum albumin (<30 g/L) were the related factors of neonatal mixed Candida/bacterial bloodstream infection (P<0.05) Multivariate analysis showed that gestational age (<37 weeks), type of infection (nosocomial infection), length of stay in NICU (≥7 days), length of hospital stay (≥14 days), invasive treatment, Apache Ⅱ score (≥15 points) and the number of antibiotics changed (≥3 kinds) were independent risk factors of neonatal mixed Candida/bacterial bloodstream infection (P< 0.05). Conclusion The main measures to reduce the new mixed bloodstream infection are to reduce the hospitalization time, stay in NICU, frequently change antibiotics and invasive diagnosis and treatment, strengthen the prevention and control of nosocomial infection and reduce the occurrence of nosocomial infection, rationally use antibiotics and reduce blind multiple replacement of antibiotics, and pay attention to the treatment of low weight and critical children.

A case of acute myeloid leukemia complicated with muscle mucormycosis after chemotherapy

ZHANG Gailing, JIA Yaqiong, ZHANG Xian

2021, 16(6): 403-406,413.

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A 47-year-old male was admitted to hospital with acute myeloid leukemia (AML). During chemotherapy he had high fever, upper right chest pain, swelling and pain of the right wrist after giving a PICC placement. During 12 days, the swelling area of the right forearm muscle tissue gradually expanded, accompanied by swelling and numbness of the right thumb and index finger. A variety of antibiotics were given successively, but the therapeutic effect failed to improve, and the high fever continued. The blood, muscle tissue and sputum samples were examined using metagenomic next-generation sequencing (mNGS). The mNGS assay revealed the pathogen presence of Rhizomucor pusillus. Once targeted antibiotic therapy with amphotericin B, liposomal amphotericin B(AmBisome), and posaconazole were administered, the infection was controlled.

A case of black dot ringworm in child

TANG Lei, ZHOU Xun, WANG Shumei

2021, 16(6): 407-409.

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A child, 2 years and 6 months old,was presented to the doctor for 10 months due to scalp scaly and black dots. The case was once misdiagnosed as 'seborrheic dermatitis’. Wood lamp examination,dermoscopy,fungal fluorescence microscopy and fungal culture on the scalp scaly and hair were carried out. Molecular biological identification was used to identify fungal species. Ultimately, Trichophyton violaceum infection caused black dot ringworm was diagnosed.The patient was cured by taking terbinafine tablets and topical treatment.

Osteolytic lesion caused by disseminated Talaromyce marneffei infection in a HIV negative patient

HUANG Chunlan, WEI Wenfei, MA Limei

2021, 16(6): 410-413.

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Talaromyce marneffei(T.marneffei)is a dimorphic fungal.There were rare reports of T.marneffei caused osteolytic destruction in non-HIV-infected cases. A patient who came from Guangxi Zhuang Autonomous Region, presented with fever, shoulder pain, weight loss, osteolytie lesion. He was HIV-negative, physical health, and did not merge the underlying disease with immune impairment. Pus of left shoulder joint and blood culture were positive for T.marneffei, His clinical status was improved and discharged after a month of amphotericin B treatment. The patient had 3 readmissions for other reasons within 2 years later. The last admitting diagnosis was septic shock.He died 6 months later due to co-infection of Mycobacterium avium-intracellulare complex (MAC) and T.marneffei probably.

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