巴西复发性和非复发性犬外耳炎的微生物谱及抗菌药物敏感性

文献信息

中文摘要

背景与目的： 犬外耳炎是一种常见的炎症性疾病，其中细菌和酵母菌的增殖可能使治疗复杂化并导致复发。在巴西，比较复发性和非复发性病例、同时表征微生物分离株及其抗菌药物敏感性的信息有限。本研究比较了复发性和非复发性外耳炎的临床、耳镜和细胞学表现，鉴定了细菌和酵母菌分离株，评估了它们对选定氟喹诺酮类和抗真菌药物的体外敏感性，并研究了临床和微生物学变量与复发之间的关联。
材料与方法： 在巴西一家兽医医院就诊的57只患有外耳炎的犬接受了耳镜和细胞学检查。对耳分泌物进行培养，并使用基质辅助激光解吸/电离飞行时间质谱法鉴定分离株。通过纸片扩散法评估抗菌药物敏感性。比较了复发性和非复发性病例的临床和细胞学表现，并使用Fisher精确检验和对数线性Poisson回归评估了与疾病状态的关联。
结果： 细胞学显示54/57（94.7%）份样本中有细菌增殖，25/57（43.9%）份样本中有酵母菌增殖。46/57（80.7%）份样本出现微生物生长，共鉴定出40株细菌分离株和16株厚皮马拉色菌分离株。葡萄球菌属是主要的细菌属（21/40；52.5%），假中间葡萄球菌是最常见的菌种（10/40；25.0%）。37.5%的细菌分离株对环丙沙星和恩诺沙星均耐药。在厚皮马拉色菌分离株中，对氟康唑（43.8%）、制霉菌素（31.3%）、两性霉素B（12.5%）和酮康唑（6.3%）出现耐药，而没有分离株对咪康唑耐药。复发与所评估的临床或微生物学变量无显著关联，尽管抗真菌耐药的厚皮马拉色菌显示出与复发性疾病关联的非显著趋势。细胞学细菌增殖与更高的预期频率关联最强（RR = 18.0，p < 0.001）。
结论： 假中间葡萄球菌和厚皮马拉色菌是从犬外耳炎中最常回收的微生物。细菌分离株中大量的氟喹诺酮类耐药支持进行培养和药敏试验，而非经验性治疗。厚皮马拉色菌分离株中可变的抗真菌耐药性，尤其是在复发病例中，值得进一步研究。这些发现为巴西犬外耳炎的抗菌药物监测和管理提供了基线数据。

英文摘要

BACKGROUND AND AIM: Canine otitis externa is a common inflammatory disorder in which bacterial and yeast proliferation may complicate treatment and contribute to recurrence. In Brazil, limited information is available comparing recurrent and non-recurrent cases while simultaneously characterizing microbial isolates and their antimicrobial susceptibility. This study compared clinical, otoscopic, and cytological findings between recurrent and non-recurrent otitis externa, identified bacterial and yeast isolates, evaluated their in vitro susceptibility to selected fluoroquinolones and antifungal agents, and investigated associations between clinical and microbiological variables and recurrence.
MATERIALS AND METHODS: Fifty-seven dogs with otitis externa presented to a veterinary hospital in Brazil were evaluated by otoscopy and cytology. Ear secretions were cultured, and isolates were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Antimicrobial susceptibility was evaluated by disk diffusion. Clinical and cytological findings were compared between recurrent and non-recurrent cases, and associations with disease status were assessed using Fisher's exact test and log-linear Poisson regression.
RESULTS: Cytology demonstrated bacterial proliferation in 54/57 (94.7%) and yeast proliferation in 25/57 (43.9%) samples. Microbial growth occurred in 46/57 (80.7%) samples, yielding 40 identified bacterial isolates and 16 Malassezia pachydermatis isolates. Staphylococcus was the predominant bacterial genus (21/40; 52.5%), and Staphylococcus pseudintermedius was the most frequent species (10/40; 25.0%). Resistance to both ciprofloxacin and enrofloxacin occurred in 37.5% of bacterial isolates. Among M. pachydermatis isolates, resistance occurred to fluconazole (43.8%), nystatin (31.3%), amphotericin B (12.5%), and ketoconazole (6.3%), whereas no isolate was resistant to miconazole. Recurrence was not significantly associated with the evaluated clinical or microbiological variables, although antifungal-resistant M. pachydermatis showed a nonsignificant trend toward association with recurrent disease. Cytological bacterial proliferation showed the strongest association with higher expected frequencies (RR = 18.0, p < 0.001).
CONCLUSION: S. pseudintermedius and M. pachydermatis were the most common microorganisms recovered from canine otitis externa. The substantial fluoroquinolone resistance among bacterial isolates supports culture and susceptibility testing rather than empirical therapy. Variable antifungal resistance among M. pachydermatis isolates, particularly in recurrent cases, warrants further investigation. These findings provide baseline data for antimicrobial surveillance and stewardship in canine otitis externa in Brazil.