Gülbudak Harun, Öztürk Candan, Kuyugöz Sibel, Tezcan Ülger Seda
Mersin University Faculty of Medicine, Department of Medical Microbiology, Mersin, Turkey.
Mersin University Faculty of Medicine, Department of Infectious Diseases and Clinical Microbiology, Mersin, Turkey.
Mikrobiyol Bul. 2021 Jan;55(1):41-52. doi: 10.5578/mb.20140.
Pneumocystis jirovecii is an atypical fungus that causes Pneumocystis pneumonia (PCP) in HIV/AIDS and immunocompromised patients. Antibiotics containing sulfa and sulfone groups are widely used in PCP prophylaxis and treatment. Especially, long-term use of trimethoprim sulfamethoxazole (TMP-SMX) is known to cause certain point mutations associated with drug resistance in the P.jirovecii dihydropteroate synthase (DHPS) gene. In addition, DHPS and mitochondrial large subunit (mtLSU) rRNA genotype characterization provides important data on the epidemiology of P.jirovecii. In this study, it was aimed to investigate the DHPS and mtLSU rRNA gene polymorphisms of P.jirovecii strains isolated from immunocompromised patients in Mersin University Hospital. In this study, 16 P.jirovecii positive samples, which isolated from 96 patients samples, between August 2016 and February 2018, were included. P.jirovecii mtLSU rRNA genotypes were determined by sequence analysis according to polymorphisms at the 85th and 248th nucleotide positions. Nested PCR and RFLP method was applied for mutation analysis of DHPS locus, 165th and 171st nucleotide positions. In the DHPS mutation analysis, 12/16 (75%) wild type (W165/W171) and 4/16 (25%) mutant type (M165/W171) were detected. Two mutant types belonged to HIV/AIDS positive patients with PCP and had a history of prophylaxis; the other 2 mutant types belonged to patients with colonization. In the study, a history of prophylaxis in 3 (19%) of the 16 patients were recorded, and mutant type was detected in these 2 of 3 patients. According to mtLSU-rRNA analysis, 3 different genotypes were obtained from 16 P.jirovecii isolates. In our region, genotype 2 (43.75%; n= 7) was the most common genotype, genotype 1 (37.5%; n= 6) was the second common and genotype 3 (18.75%; n= 3) was the least one. Genotype 4 was not detected in our region. When DHPS and mtLSU-rRNA were evaluated as multilocus, five different genotypes were observed. As a result, these findings provided important data on P.jirovecii epidemiology in our region and potential drug-resistant strains showed a risk of transmission in immunosuppressive patients. Multicenter studies involving more P.jirovecii isolates are needed to better define the epidemiology of P.jirovecii in our region and in our country.
耶氏肺孢子菌是一种非典型真菌，可在艾滋病毒/艾滋病患者和免疫功能低下患者中引起肺孢子菌肺炎（PCP）。含磺胺和砜基团的抗生素广泛用于PCP的预防和治疗。特别是，长期使用复方磺胺甲恶唑（TMP-SMX）已知会导致耶氏肺孢子菌二氢蝶酸合酶（DHPS）基因中与耐药性相关的某些点突变。此外，DHPS和线粒体大亚基（mtLSU）rRNA基因型特征为耶氏肺孢子菌的流行病学提供了重要数据。在本研究中，旨在调查梅尔辛大学医院免疫功能低下患者分离出的耶氏肺孢子菌菌株的DHPS和mtLSU rRNA基因多态性。在本研究中，纳入了2016年8月至2018年2月期间从96份患者样本中分离出的16份耶氏肺孢子菌阳性样本。根据第85和248个核苷酸位置的多态性，通过序列分析确定耶氏肺孢子菌mtLSU rRNA基因型。采用巢式PCR和RFLP方法对DHPS基因座第165和171个核苷酸位置进行突变分析。在DHPS突变分析中，检测到12/16（75%）野生型（W165/W171）和4/16（25%）突变型（M165/W171）。两种突变型属于患有PCP且有预防史的艾滋病毒/艾滋病阳性患者；另外两种突变型属于定植患者。在该研究中，16名患者中有3名（19%）有预防史，在这3名患者中的2名检测到突变型。根据mtLSU-rRNA分析，从16株耶氏肺孢子菌分离物中获得了3种不同基因型。在我们地区，基因型2（43.75%；n = 7）是最常见的基因型，基因型1（37.5%；n = 6）是第二常见的，基因型3（18.75%；n = 3）是最不常见的。在我们地区未检测到基因型4。当将DHPS和mtLSU-rRNA作为多位点进行评估时，观察到五种不同基因型。结果，这些发现为我们地区耶氏肺孢子菌的流行病学提供了重要数据，潜在的耐药菌株在免疫抑制患者中显示出传播风险。需要开展涉及更多耶氏肺孢子菌分离物的多中心研究，以更好地确定我们地区和我国耶氏肺孢子菌的流行病学情况。
