Köhne Martin, Hüsch Ronja, Peh Elisa, Hirnet Juliane, Tönissen Anna, Müsken Mathias, Plötz Madeleine, Kittler Sophie, Sieme Harald
Unit for Reproductive Medicine, Clinic for Horses, University of Veterinary Medicine, Foundation, Bünteweg 15, 30559, Hannover, Germany.
Institute of Food Quality and Food Safety, University of Veterinary Medicine, Bischofsholer Damm 115, 30173, Foundation, Hannover, Germany.
BMC Vet Res. 2025 Oct 3;21(1):568. doi: 10.1186/s12917-025-04989-1.
Bacterial infections of the genital tract are a severe problem in equine reproduction. Biofilms produced by Klebsiella (K.) pneumoniae and Pseudomonas (P.) aeruginosa present further concerns in such cases as they can limit the success of antibiotic treatments. Alternative treatment approaches are urgently needed for treating bacterial equine genital tract infections and thus, reduce antibiotic use. The present study reports on the bactericidal efficacy of both, novel K. pneumoniae- and P. aeruginosa-specific phages, in a biofilm model and in conjunction with antibiotic drugs as tested in vitro.
In total, 15 phages with lytic activity (K. pneumoniae: n = 6; P. aeruginosa: n = 9) were isolated and host ranges were determined. Four phages with a broad host range (K. pneumoniae: n = 3; P. aeruginosa: n = 1) were selected for further characterization, including electron microscopy and whole genome sequencing. Significant bacterial growth reduction was observed in planktonic killing assays at three multiplicities of infection (MOI 1, MOI 10, MOI 100), when the phages vB_KpnS_LmqsRe28-1, vB_KpnS_LmqsRe28-2, vB_KpnM_LmqsRe27-1 or vB_PaeS-LmqsRe25-1 were added. In addition, planktonic killing assays were used to examine the four phages in conjunction with gentamicin, enrofloxacin and trimethoprim-sulfadiazine in vitro. The results indicate synergistic activities between the four phages and the investigated antibiotics. However, bacterial growth was not affected in biofilm models after phage treatment, likely due the absence of depolymerase genes in the sequenced phages.
Phages against the equine genital pathogens K. pneumoniae and P. aeruginosa were evaluated in vitro for potential clinical use. While the bactericidal activity of the isolated phages was demonstrated in liquid culture, none of the tested phages showed significant reduction in in vitro biofilm models. However, due to synergistic activities between phages and antibiotics, further studies on combinatorial approaches are needed to develop strategies for managing difficult infections.
生殖道细菌感染是马繁殖中的一个严重问题。肺炎克雷伯菌和铜绿假单胞菌产生的生物膜在这种情况下更令人担忧，因为它们会限制抗生素治疗的成功率。迫切需要替代治疗方法来治疗马生殖道细菌感染，从而减少抗生素的使用。本研究报告了新型肺炎克雷伯菌特异性噬菌体和铜绿假单胞菌特异性噬菌体在生物膜模型中以及与体外测试的抗生素联合使用时的杀菌效果。
总共分离出15种具有裂解活性的噬菌体（肺炎克雷伯菌：n = 6；铜绿假单胞菌：n = 9），并确定了宿主范围。选择了4种具有广泛宿主范围的噬菌体（肺炎克雷伯菌：n = 3；铜绿假单胞菌：n = 1）进行进一步表征，包括电子显微镜和全基因组测序。当添加噬菌体vB_KpnS_LmqsRe28 - 1、vB_KpnS_LmqsRe28 - 2、vB_KpnM_LmqsRe27 - 1或vB_PaeS - LmqsRe25 - 1时，在三种感染复数（MOI 1、MOI 10、MOI 100）下的浮游菌杀灭试验中观察到细菌生长显著减少。此外，使用浮游菌杀灭试验在体外检测这4种噬菌体与庆大霉素、恩诺沙星和甲氧苄啶 - 磺胺嘧啶的联合使用情况。结果表明这4种噬菌体与所研究的抗生素之间具有协同活性。然而，噬菌体处理后生物膜模型中的细菌生长未受影响，可能是由于测序的噬菌体中不存在解聚酶基因。
对针对马生殖道病原体肺炎克雷伯菌和铜绿假单胞菌的噬菌体进行了体外潜在临床应用评估。虽然在液体培养中证明了分离噬菌体的杀菌活性，但在体外生物膜模型中，没有一种测试噬菌体显示出显著的减少效果。然而，由于噬菌体与抗生素之间的协同活性，需要对联合方法进行进一步研究，以制定管理难治性感染的策略。
