biostudies-literatureUnknown17(11)de Villiers de la Noue H<i>Acinetobacter baumannii</i> is a critical public health threat, particularly with the rise in multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains that limit treatment options. Phage therapy, which uses bacteriophages to target bacteria, offers a promising alternative. We isolated an XDR strain (Ab125) from a burn wound infection and screened 34 phages, identifying vB_AbaM_3098 as the only effective candidate. However, resistance rapidly emerged, producing a derivative strain (Ab139). Interestingly, Ab139, though resistant to vB_AbaM_3098, became susceptible to six previously inactive phages. While various potential determinants were identified through comparative genomics and proteomics, the mechanism causing phage resistance to vB_AbaM_3098 and simultaneous susceptibViruses1441https://www.ebi.ac.uk/biostudies/studies/S-EPMC12656882biostudies-literatureRational Design of a Potent Two-Phage Cocktail Against a Contemporary &lt;i&gt;Acinetobacter baumannii&lt;/i&gt; Strain Recovered from a Burned Patient at the Lausanne University Hospital.PMC12656882de Villiers de la Noue HVuattoux XResch GGolliard GfalseRational Design of a Potent Two-Phage Cocktail Against a Contemporary &lt;i&gt;Acinetobacter baumannii&lt;/i&gt; Strain Recovered from a Burned Patient at the Lausanne University Hospital.<i>Acinetobacter baumannii</i> is a critical public health threat, particularly with the rise in multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains that limit treatment options. Phage therapy, which uses bacteriophages to target bacteria, offers a promising alternative. We isolated an XDR strain (Ab125) from a burn wound infection and screened 34 phages, identifying vB_AbaM_3098 as the only effective candidate. However, resistance rapidly emerged, producing a derivative strain (Ab139). Interestingly, Ab139, though resistant to vB_AbaM_3098, became susceptible to six previously inactive phages. While various potential determinants were identified through comparative genomics and proteomics, the mechanism causing phage resistance to vB_AbaM_3098 and simultaneous susceptib2025-01-01T00:00:00Z2025 Oct2026-07-05T03:16:37.366Z2026-07-05T03:08:18.152ZS-EPMC126568824130546410.3390/v17111441