Ahirwar Lalit Kishore, Sheba Esther, Jakati Saumya, Jayasudha Rajagopalaboopathi, Padakandla Shalem Raj, Bagga Bhupesh, Sharma Savitri
Jhaveri Microbiology Centre, Brien Holden Eye Research Centre, L. V. Prasad Eye Institute, Kallam Anji Reddy Campus, L. V. Prasad Marg, Banjara Hills, Hyderabad-500034, India.
Ophthalmic Pathology Laboratory, Kallam Anji Reddy Campus, L. V. Prasad Marg, Banjara Hills, Hyderabad-500034, India.
Med Mycol. 2022 Apr 26. doi: 10.1093/mmy/myac024.
This study reports the clinico-microbiological features of Macrophomina phaseolina keratitis. Clinically diagnosed as microbial keratitis, six patients underwent microbiological evaluation. Fungal culture isolates from cornea were subjected to DNA sequencing of the ITS region, phylogenetic analysis and reconfirmation by polymerase chain reaction (PCR). Minimum inhibitory concentrations (MICs) of six antifungal drugs were determined by microbroth dilution method against the six isolates. All patients were treated with antifungals. Failed medical therapy necessitated therapeutic penetrating keratoplasty (TPK). Corneal buttons were processed for histopathology. In all patients, the corneal scraping showed septate hyaline fungal filaments. The BLAST analysis for ITS sequences of all six fungal isolates suggested M. phaseolina, however, when limited to sequences from type material, they matched M. pseudophaseolina. Phylogenetic analysis could not differentiate between these two species and clustered in a single clade. PCR assay of specific gene sequence [MpCal (calmodulin)] reconfirmed all isolates as M. phaseolina. The MICs of voriconazole and posaconazole were lowest (0.03 to 2 and 0.1 to 2µg/mL respectively) and all isolates were susceptible to natamycin. Except for case 1, which healed with a scar on treatment, all other cases worsened, despite medical treatment, necessitating TPK. Histopathology of 3 out of 4 buttons showed the presence of fungal filaments. While direct microscopic examination of corneal scrapings is helpful in diagnosis, identification of M. phaseolina in culture is challenging. Although MICs of commonly used antifungals are low response to medical therapy is not encouraging; patients may require TPK for resolution of infection in M. phaseolina keratitis.
本研究报告了菜豆壳球孢菌角膜炎的临床微生物学特征。6例临床诊断为微生物性角膜炎的患者接受了微生物学评估。对角膜真菌培养分离株进行ITS区域的DNA测序、系统发育分析，并通过聚合酶链反应（PCR）进行重新确认。采用微量肉汤稀释法测定6种抗真菌药物对6株分离株的最低抑菌浓度（MIC）。所有患者均接受抗真菌治疗。药物治疗失败后需要进行治疗性穿透性角膜移植术（TPK）。对角膜植片进行组织病理学检查。所有患者的角膜刮片均显示有分隔的透明真菌丝。对所有6株真菌分离株的ITS序列进行BLAST分析提示为菜豆壳球孢菌，然而，当仅限于模式标本的序列时，它们与拟菜豆壳球孢菌匹配。系统发育分析无法区分这两个物种，它们聚集在一个单系分支中。对特定基因序列[MpCal（钙调蛋白）]的PCR检测再次确认所有分离株均为菜豆壳球孢菌。伏立康唑和泊沙康唑的MIC最低（分别为0.03至2和0.1至2μg/mL），所有分离株对那他霉素敏感。除病例1在治疗后留有瘢痕愈合外，其他所有病例尽管接受了药物治疗仍病情恶化，需要进行TPK。4个植片中3个的组织病理学检查显示有真菌丝。虽然角膜刮片的直接显微镜检查有助于诊断，但在培养中鉴定菜豆壳球孢菌具有挑战性。尽管常用抗真菌药物的MIC较低，但对药物治疗的反应并不理想；菜豆壳球孢菌角膜炎患者可能需要进行TPK才能解决感染问题。
