Table of Content

28 August 2018, Volume 13 Issue 4

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论文

The mechanism of Sporothrix globosa melanins protect against antifungal drugs

CUI Yan, LI Shan-shan, HOU Yuan-yuan, SONG Yang, CHEN Rui-li, LI Hong-xia

2018, 13(4):  193-196,212. 

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Objective To investigate the effects of Sporothrix globosa melanins on four antifungal agents (TRB, FCZ, ICZ and AMB). Methods The agar plate coating method was used to compare the susceptibility of wild-type strain (MEL⁺) and albino mutant (MEL^-) to antifungal drugs; the effect of melanin on the antifungal drug was detected by ultraviolet spectrophotometry. The HPLC was used to analyze the mechanism of melanins against fungal drugs. Results Antifungal drugs susceptibility results showed that the MEL^- survival rate was significantly lower than MEL⁺ at concentrations of 4~16 μg/mL for AMB and 0.06-0.25 μg/mL for ICZ; the results of UV spectrophotometry assay showed that melanin could significantly reduce the concentration of AMB (P<0.01); the chromatogram of HPLC showed that, compared with control group, new peak was appeared after the addition of melanin.Conclusion Sporothrix globosa melanins can protect against AMB and ICZ, and reduce AMB concentration through transforming, probably.

The features and mechanisms of Candida tropicalis resistance in vitro induced by different azoles

FAN Xin, HUANG Jing-jing, HOU Xin, XIAO Meng, ZHANG Li, XU Ying-chun

2018, 13(4):  197-200. 

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Objective To compare the features of different azoles in vitro induction of azole resistance in Candida tropicalis, and related resistant mechanisms.Methods A clinical azole-susceptible isolate was consecutively subcultured in liquid medium containing 16 μg/mL of fluconazole, 2 μg/mL of voriconazole or 1 μg/mL of posaconazole, respectively, for 50 generations. Antifungal susceptibility testing was performed by colorimetric broth microdilution method. The azoles target gene, ERG11, of the 50^th generation isolates were amplified and sequenced. In addition, the expression level of ERG11, and efflux pump-encoding gene MDR1, CDR1, as well as cytochrome b-encoding gene CYTb, were determined by real-time quantitative PCR.Results Azole resistance was emerged very fast when under in vitro exposure to fluconazole or voriconazole, whilst the isolates induced by posaconazole remained susceptible. However, the resistance features of isolates induced by fluconazole and voriconazole were different. The MICs of isolates induced by fluconazole were gradually increased, while MICs of isolates induced by voriconazole had a jump rise. By resistant mechanism study, a G/G1390G/A heterozygous mutation being responsible for azole resistance was detected in ERG11 gene of voriconazole-induced isolate. The real-time PCR results showed that, only the expression of CDR1 gene in fluconazole-induced isolates increased significantly.Conclusions Azole resistance amongst C.tropicalis isolates emerged rapidly under in vitro exposure to fluconazole or voriconazole, but the resistant features and mechanisms were different.

Inactivation of Candida albicans CaMIT1 gene with CRISPR/Cas9 approach and the phenotype analysis of its homozygous mutant

XU Hui-hui, JIANG Ling-huo

2018, 13(4):  201-207. 

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Objective To construct mutants for C.albicans CaMIT1 and investigate its functions in C. albicans.Methods We constructed the inactivated mutant for CaMIT1 with the novel approach CRISPR (Clustered Regularly Interspaced Short Palindromic Repeat)/Cas9. Serial dilution assay was used to analyze the function of CaMIT1. Results We successfully constructed the homozygous inactivation mutant for CaMIT1, and phenotypic analysis revealed that the homozygous mutant was sensitive to calcium and lithium ions, sodium dodecyl sulfate, clotrimazole, ketoconazole and anidualafungin, but tolerant to Congo Red. Conclusions CaMIT1 is involved in the integrity of plasma membrane and cell wall as well as the calcium homeostasis.

Prokaryotic expression of Cryptococcus neoformans laccase

DENG Dong-ling, KONG Qing-tao, ZHANG Yuan-yuan, YUAN Hong-shan, LIU Hui, SANG Hong

2018, 13(4):  208-212. 

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Objective To construct a prokaryotic expression vector of Cryptococcus neoformans laccase containing His-tag and to express and identify it.Methods The coding sequence of LAC1 gene was amplified by PCR and correctly inserted into pET-28a (+) vector to obtain the recombinant plasmid. The recombinant plasmid was transformed into E.coli DH5α competent cells for PCR identification and gene sequencing. The correct recombinant plasmid was transformed into E. coli BL21 (DE3) competent cells. Induction expression was carried out under different conditions, and the target protein was detected and identified by SDS-PAGE electrophoresis and MALDI-TOF mass spectrometry. Inclusion body protein was denatured by urea and identified by SDS-PAGE electrophoresis and MALDI-TOF mass spectrometry.Results The prokaryotic expression vector of Cryptococcus neoformans laccase containing His-tag was constructed and confirmed by PCR, and the result of sequencing was consistent with the target sequence. The SDS-PAGE showed that the target protein with molecular mass(MR) about 68 000 was successfully induced to express in E. coli BL21(DE3). And identification by MALDI-TOF mass spectrometry demonstrated that the target protein is insoluble in this expression system and may exist in the form of inclusion body. Conclusion The prokaryotic expression vector of Cryptococcus neoformans laccase containing His-tag was successfully constructed. This laid the foundation for further purification and analysis of the crystal structure of Cryptococcus neoformans laccase.

Risk factors of invasive pulmonary aspergillosis in patients with Hepatitis B virus-related acute-on-chronic liver failure

LI Ming, WU Zhen-ping, CHENG Xiao-yu, YU Ting-ting, LI Xiao-peng, ZHANG Lun-li, ZHANG Wen-feng

2018, 13(4):  213-216,228. 

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Objective To investigate the incidence, risk factors and prognosis of invasive pulmonary aspergillosis (IPA) in patients with Hepatitis B virus-related acute-on-chronic liver failure (HBV-ACLF). Methods The clinical data of 283 patients with Hepatitis B virus-related acute-on-chronic liver failure (HBV-ACLF) who were hospitalized in our department from January 2015 to January 2017 were recorded. All patients were divided into IPA group and control group according to the status of invasive pulmonary aspergillosis during hospitalization. Results Among the 283 patients with hepatitis B virus-related acute-on-chronic liver failure, 39 cases of definite or probable pulmonary aspergillosis were diagnosed during hospitalization, the incidence was 13.78% (39/283). There were statistically differences (P<0.05) between pulmonary aspergillosis group and control group in type 2 diabetes mellitus, pulmonary underlying diseases, admission baseline TBiL level, MELD score, usage of glucocorticoid, usage of broad-spectrum potent antibiotic, femoral vein catheterization, hospital floor comparison. Logistic regression analysis showed that the risk factors of pulmonary aspergillosis in patients with HBV-ACLF were type 2 diabetes mellitus (OR=8.981,P=0.002), pulmonary basal disease (OR=8.525,P=0.000), usage of glucocorticoid (OR=8.856, P=0.000), usage of broad-spectrum potent antibiotics (OR=9.823,P=0.000). Thirty-one patients with HBV-ACLF and secondary IPA died, the mortality rate was 79.48% (31/39). Conclusion The hospitalized hepatitis B virus related acute-on-chronic liver failure patients were predisposed to invasive pulmonary aspergillosis. Type 2 diabetes mellitus, pulmonary underlying diseases, usage of corticosteroids or broad spectrum antibiotics might be risk factors for pulmonary aspergillosis. Once HBV-ACLF patients complicated with IPA, they might have a poorer prognosis.

Literature review of skin and soft tissue infections caused by Candida spp.

CHEN Ping, ZHOU Ya-bin, LI Dong-ming

2018, 13(4):  217-222. 

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Objective To analyze clinical feature of skin and soft tissue infections caused by Candida spp.Methods Perform discriptive analysis of Candida infection case reports published from 1984-2017 in Pubmed, Wanfang and CNKI Database. Results Thirty-five patients in 32 literatures were analyzed. Every age group was involved worldwide, with more cases in China, roughly the same proportion of males and females. Almost all of the patients had an underlying disease or predisposing factors. Deep skin and soft tissue infections caused by Candida spp. had various clinical manifestations. More than half of cases showed skin ulcers.Facial midline area ulcers were not unusual, which could also simulate the clinical manifestations of many diseases such as folliculitis, cellulitis, necrotizing fasciitis and so on, or presented as subcutaneous abscess, skin patches, ect. All cases were confirmed by fungal culture. Pseudohyphae and (or) spores could be found in histopathological examination.Conclusion Deep skin and soft tissue infections caused by Candida spp. had various clinical features, which mostly manifested as ulcers, and could simulate a variety of diseases, easily leading to misdiagnosis. Pseudohyphae and (or) spores could be found in histopathological examination. Patients with limited lesion or mildly underlying disease had a favourable prognosis, severe underlying disease or the emergence of systematic spread could cause death. The main pathogen was Candida albicans.

Disruption and functional characterization of SIM1 gene in Candida albicans

ZHANG Xiao-long, LU Ren-yi, YAN Lan, JIANG Yuan-ying

2018, 13(4):  223-228. 

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Objective To construct deletion mutants for Candida albicans SIM1 and explore its functions. Methods Using homologous recombination method to construct deletion mutants for Candida albicans SIM1, by measuring the growth curve, hyphae induction, adhesion epithelial cells and conducting other experiments to observe its phenotypes. Results Gene deletion mutants of SIM1 were successfully constructed. Deletion mutants of SIM1 did not significantly affect the growth and reproduction, hyphae and biofilms formation of Candida albicans, but its adhesive ability to Caco-2 cells and KB cells was obviously impaired. Furthermore deletion mutants of SIM1 were more sensitive to some drugs. Conclusions Deletion mutants of SIM1 result in changes in cell wall composition and affect the adhesion of Candida albicans to hosts.

The study of the pathogenic spectrum and epidemiologic features of invasive fungal infection in China during 2008-2017

HE Xiao-yang, REN Qiu-xia, YANG Ying

2018, 13(4):  229-234. 

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Objective To explore the pathogenic spectrum and the epidemiologic features of invasive fungal infection in China during 2008-2017.Methods All the related literature of deep mycosis reported from Jan.2008-Dec. 2017 in CNKI and Wanfang database were searched and analyzed by Excel 2007,retrospectively. Results 94526 cases from 464 articles published in hospitals at all levels in China were obtained, involving more than 20 clinical specimens and more than 27 infected sites. In the past 10 years, the spectrum of the pathogenic fungi in China were generally stable, there were 9 species of the main pathogenic fungi, including Candida, Aspergillus, Penicillium, Cryptococcus and Sporotrichosis. Candida albicans was the most common specie of the pathogen fungi, accounting for 92% of the total number of cases, meanwhile, the proportion of Candida albicans account for 65% of the total Candida, However, the ratio of Candida albicans infection decreased by 12% in 10 years; respiratory tract and lung were the most frequent sites of pathogenic fungal infection; the Yangtze River region and Lingnan region in warm and humid climate were the most often reported area of deep mycosis. Conclusion In the past 10 years, the main pathogenic fungi of invasive fungal infection in China were Candida, of which Candida albicans was the prominent fungal pathogen but with a downward trend, respiratory and lung were the most reported infection sites, the population structure of pathogen fungi in most areas of China were similar, and the Yangtze River region and Lingnan region in warm and humid climate were the main areas of deep mycosis.

Tinea capitis in a newborn caused by Microsporum canis: a case report

GUO Yan-yang, FU meng, MA Cui-ling

2018, 13(4):  239-240. 

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One case of tinea capitis by Microsporum canis in a newborn was reported. A 21-day-old female newborn, presented with a 7-day history ofring-shaped erythema, papules, blister, and scales at the top of her head. Fungal microscopic examination revealed mycelium positive. The SDA culture presented white-woolly surface, yellow-brown-base, yellowish-brown-back. And the rice culture shows spindle shaped with slightly curved apex, thick wall and spinous protuberances, with 6-12 divisions. All those indicates the infection of Tinea capitis caused by Microsporum canis. Given by the topical treatment of sertaconazole nitrate cream and terbinafine hydrochloride twice a day for 7 days, her lesions subsided.

A case of Majocchi's granuloma (MG) and onychomycosis caused by Trichophyton rubrum in a renal transplant recipient

HU Xiao-ping, GAO Lu-juan, YOU Li-ping, LI Ruo-yu

2018, 13(4):  241-243. 

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We report a case of Majocchi's granuloma (MG) and onychomycosis caused by Trichophyton rubrum in a renal transplant recipient. The 73-year-old female patient had undergone left renal transplantation six years earlier for uremia and had been immunosuppressed with low daily doses of tacrolimus and azathioprine. While under this treatment, she presented with a one-month history of painful blue-red papules and nodules on an erythematous base on her left leg and both feet. She also had onychomycosis on toenails for ten years, which worsened post transplantation. We performed physical, pathological and mycological examination. The clinical diagnosis concluded that the disease was MG, onychomycosis and tinea pedis caused by Trichophyton rubrum. Further investigation demonstrated that the three strains isolated from the deep and superficial areas were identical. Oral intake of terbinafine tablets (500 mg/d) and topical application of terbinafine cream for 12 wks completely cured the lesions in the skin and nails.

Research on functions of mononuclear cells in fungal infection

DONG Jia-cheng, LIANG Guan-zhao, LIU Wei-da

2018, 13(4):  244-246. 

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Monocytes participate in the inflammatory response and activate at the site of microbial infection. However, the specific antifungal effect of monocytes is still unclear. Monocytes are heterogeneous and present in multiple subsets that play different roles in immune system. This article aims to investigate the functions of different phenotypic mononuclear cells in fungal infections (such as Candida, Cryptococcus and Aspergillus fumigatus) and provides new idea for understanding the mechanism of antifungal immunity, and monitoring fungal diseases.

Research progress in the diagnosis and treatment of Pneumocystis pneumonia

HE Xiao-qing, SHEN Yin-zhong

2018, 13(4):  247-251. 

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Objective To review the progress in the diagnosis and treatment of Pneumocystis pneumoniae (PCP). Methods The progress of PCP diagnosis and treatment was summarized by literature retrieving and analyzing literature. Results The clinical diagnosis of PCP is mainly based on the basic condition of immunodeficiency or immune suppression, and typical clinical and imaging manifestations, and the definite diagnosis depends on etiological examination. In recent years, many studies have shown that PCR and serum (1,3)-beta-D-glucan assay are helpful to the early diagnosis of PCP and to distinguish colonization and infection of Pneumocystis. Compound sulfamethoxazole (SMZco) is the preferred drug for the treatment of PCP, in addition, caspofungin was combined with SMZco to treat PCP in recent years, but its value in PCP treatment remains to be further studied. Conclusion The diagnosis of PCP mainly depends on clinical presentations. SMZco is the first choice for PCP treatment. Exploring the early diagnosis technology of PCP and improving the success rate of critical cases is the focus of future research.

Prevention and treatment for invasive fungal infection in patients with hematological malignancies

ZUO Wei, XIAO Qing

2018, 13(4):  252-256. 

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Invasive fungal infection is one of the common complications in patients with malignant blood tumor, which leads to a high mortality rate. Over the past decade, with the gradual improvement of the diagnosis and treatment, the establishment of primary and secondary prevention, and the application of new antifungal drugs, the incidence of the disease is lower than before, but the mortality is still high. Reasonable and effective prevention and treatment can reduce the mortality of fungal infection in patients with hematological malignancies. This review summarizes the prevention, treatment strategies and existing problems of invasive fungal disease in patients with hematological malignancies.