AbstractCitrobacter koseriis an emerging Gram-negative bacterial pathogen, which causes urinary tract infections. We isolated and characterized a novel S16-like myovirus CKP1 (vB_CkoM_CkP1), infectingC. koseri. CkP1 has a host range covering the wholeC. koserispecies,i.e., all strains that were tested, but does not infect other species. Its linear 168,463-bp genome contains 291 coding sequences, sharing sequence similarity with theSalmonellaphage S16. Based on surface plasmon resonance and recombinant green florescence protein fusions, the tail fiber (gp267) was shown to decorateC. kosericells, binding with a nanomolar affinity, without the need of accessory proteins. Both phage and the tail fiber specifically bind to bacterial cells by the lipopolysaccharide polymer. We further demonstrate that CkP1 is highly stable towards different environmental conditions of pH and temperatures and is able to controlC. kosericells in urine samples. Altogether, CkP1 features optimal in vitro characteristics to be used both as a control and detection agent towards drug-resistantC. koseriinfections.Key points•CkP1 infects all C. koseri strains tested•CkP1 recognizes C. koseri lipopolysaccharide through its long tail fiber•Both phage CkP1 and its tail fiber can be used to treat or detect C. koseri pathogensSupplementary InformationThe online version contains supplementary material available at 10.1007/s00253-023-12547-8.