Fatal Suppurative Bronchopneumonia Associated With Multidrug‐Resistant Klebsiella pneumoniae in a Pet Rat ( Rattus norvegicus ): A Case Report

Respiratory diseases are common in companion rodents, but empirical treatment without microbiological diagnosis remains widespread, contributing to treatment failures and the selection of resistant strains. This study reports a case of fatal suppurative bronchopneumonia associated with a multidrug‐resistant (MDR) Klebsiella pneumoniae isolate in a pet rat ( Rattus norvegicus ). Following clinical presentation, serial thoracic radiographs were obtained, and empirical antimicrobial and respiratory therapies were administered. Because of progressive disease, the animal was humanely euthanized. Necropsy revealed multiple pulmonary abscesses, hemorrhage, and emphysema, with histopathology consistent with severe neutrophilic bronchopneumonia. K. pneumoniae was isolated from lung tissue in pure culture. Antimicrobial susceptibility testing according to BrCAST guidelines demonstrated resistance to doxycycline, chloramphenicol, enrofloxacin, marbofloxacin, and norfloxacin; intermediate susceptibility to cefazolin, streptomycin, gentamicin, and trimethoprim–sulfamethoxazole; and susceptibility to amikacin, aztreonam, ceftriaxone, cefotaxime, ceftazidime, and cefepime. This resistance profile provides a plausible explanation for the failure of empirical therapies with doxycycline and fluoroquinolones, although advanced pulmonary abscessation and lack of antemortem testing also influenced the outcome. The absence of molecular characterization and environmental screening limits definitive transmission inferences. Early microbiological investigation is essential to guide effective therapy, support antimicrobial stewardship, and mitigate potential public health risks at the human–animal interface within the One Health framework.