Chromobacteriosis (Chromobacterium violaceum) in a calf from Brazil - case report

Impact of Prophylactic Antibiotic Use in Ornamental Fish Tanks on Microbial Communities and Pathogen Selection in Carriage Water in Hong Kong Retail Shops

Antibiotics are routinely added to ornamental fish tanks for treating bacterial infection or as a prophylactic measure. However, the overuse or subtherapeutical application of antibiotics could potentially facilitate the selection of antibiotic resistance in bacteria, yet no studies have investigated antibiotic use in the retail ornamental fish sector and its impact on microbial communities. The present study analyzed the concentrations of twenty antibiotics in the carriage water (which also originates from fish tanks in retail shops) collected monthly from ten local ornamental fish shops over a duration of three months. The antibiotic concentrations were correlated with the sequenced microbial community composition, and the risk of resistance selection in bacteria was assessed. Results revealed that the detected concentrations of tetracyclines were the highest among samples, followed by fluoroquinolones and macrolides. The concentrations of oxytetracycline (44.3 to 2,262,064.2 ng L-1) detected across three months demonstrated a high risk for resistance selection at most of the sampled shops. Zoonotic pathogens (species of Rhodococcus, Legionella, and Citrobacter) were positively correlated with the concentrations of oxytetracycline, tetracycline, chlortetracycline, and enrofloxacin. This suggests that antibiotic use in retail shops may increase the likelihood of selecting for zoonotic pathogens. These findings shed light on the potential for ornamental fish retail shops to create a favorable environment for the selection of pathogens with antibiotics, thereby highlighting the urgent need for enhanced antibiotic stewardship within the industry.

Sepsis in cougar (Puma concolor) associated with Chromobacterium violaceum

The genus Chromobacterium is widely distributed in the environment and is composed of Gram-negative, aerobic, or facultative anaerobic bacilli that occur in violet-colored colonies. These bacteria rarely cause infections, but when it occurs, it spreads quickly and has a high mortality. Because diseases are infrequent, the diagnosis is often delayed, and it takes time for suitable treatment to be initiated, leading to increased mortality due to the rapid progression of the disease. After the death of a cougar, serologically positive for feline leukemia virus, at the Center for Medicine and Research on Wild Animals of the Federal University of Mato Grosso, an autopsy was carried out, and fragments of its organs were sent for bacterial culture. Significant lesions were found, mainly in the liver and lungs, and upon bacterial isolation, violet-colored colonies were obtained from all of the referred organs, suggestive of C. violaceum, which was later confirmed by 16S DNA sequencing. The objective of this study was to report a case of death associated primarily with disseminated infection caused by C. violaceum in a FeLV-positive wild cougar in July 2018; no other occurrence in this species has yet been described.