This experiment aimed to investigate the elimination profile of phenoxymethylpenicillin（penicillin V potassium）soluble powder in eggs. Ten healthy laying hens meeting the required egg production criteria. They were administered the drug orally via drinking water at the maximum recommended clinical dose of 20 mg/kg B.W./d for 5 consecutive days. Freshly prepared medicated water was provided daily and ensured to be fully consumed by the flock.Eggs were collected daily at fixed time points from the start of administration until 14 days after the last dose，with detailed records maintained. Quantitative analysis was performed using an internal standard method. After sample pretreatment，penicillin V residues in eggs were determined by LC?MS/MS. The method demonstrated good linearity within the concentration range of 5－200 ng/mL，with a limit of detection of 5 μg/kg. Recoveries ranged from 96% to 101.4%，with RSD≤3.5%. Penicillin V residues were rapidly eliminated from eggs，falling below the detection limit by the first day post?treatment. Based on the maximum residue limit（MRL）regulations for penicillin V，a withdrawal period of zero days is recommended for phenoxymethylpenicillin soluble powder in laying hens.

In July 2025，a suspected case of Burkholderia pseudomallei infection was reported at a municipal hospital in a certain city of Hunan Province. To determine the cause，analyze potential risk factors and inform timely control measures，an emergency field epidemiological investigation was conducted using site inspections，household interviews，and laboratory testing. Investigation results showed that contact animals exhibited normal clinical health and tested negative in the mallein test，ruling out the risk of Burkholderia pseudomallei infection. Metagenomic sequencing identified that Burkholderia multivorans as the predominant pathogen in patient samples.