# Distribution and Antimicrobial Resistance Patterns of Aerobic Bacterial Isolates from Clinically Ill Pet Guinea Pigs (Cavia porcellus) in Hong Kong

## TL;DR

This study found high antimicrobial resistance in bacteria from sick pet guinea pigs in Hong Kong, highlighting the need for careful antibiotic use in exotic pets.

## Contribution

The study provides the first detailed analysis of antimicrobial resistance patterns in clinically ill pet guinea pigs in Hong Kong.

## Key findings

- Over half of the samples from ill guinea pigs showed bacterial growth, with 27.6% being multidrug-resistant.
- High resistance was observed for penicillin, gentamicin, doxycycline, and azithromycin, while ceftazidime and chloramphenicol showed high susceptibility.
- Most bacterial isolates were Gram-positive, with common species including Streptococcus, Staphylococcus, and Corynebacterium.

## Abstract

Antimicrobial resistance (AMR) is an escalating global health concern, where bacteria evolve to withstand antibiotics that once effectively treated infections. This study investigated bacterial infections and AMR in pet guinea pigs in Hong Kong. We reviewed 234 medical records of ill guinea pigs from 2019 to 2023 to identify the most common bacterial infections and assess their resistance to antibiotics. Over half of the samples showed bacterial growth, with many strains resistant to commonly used antibiotics. Alarmingly, more than a quarter were multidrug-resistant, complicating treatment options. Some antibiotics traditionally considered safe for guinea pigs may also be less effective due to rising resistance levels. These findings underscore the need for responsible antibiotic use in exotic pets and suggest that pet guinea pigs may contribute to the broader spread of resistant bacteria. This information can guide veterinarians in selecting more effective treatments and increase awareness of AMR in companion animals.

With the increase in keeping exotic companion mammals as pets, concerns about antimicrobial resistance (AMR) and its impact on animal and human health are growing. Guinea pigs, a popular pet in Hong Kong and globally, have limited studies regarding antimicrobial culture and sensitivity results. We reviewed bacteriologic and antimicrobial sensitivity results from clinically ill pet guinea pigs from 2019 to 2023 using data from the City University Veterinary Diagnostic Laboratory. Of the 234 clinical samples from 22 veterinary clinics in Hong Kong, 134 (57.3%) showed positive bacterial growth, of which 23 (17.2%) showed mixed bacterial growth. In total, 156 bacterial isolates were identified. Gram-positive bacteria (n = 104, 66.7%) were most commonly recovered, representing 25 bacterial species, most commonly Streptococcus spp., Staphylococcus spp., and Corynebacterium spp. The majority of positive samples were from the integument (43.6%) and urinary tract (33.8%). A total of 85.9% of all isolates were resistant to at least one antimicrobial agent, with over 40% of isolates exhibiting resistance to three or more antimicrobial agents, and 27.6% were multidrug resistant (resistant to at least one agent in three or more antimicrobial classes). High resistance rates were observed for penicillin (45.6%), gentamicin (43.7%), doxycycline (42.1%), and azithromycin (36.3%). In contrast, isolates were highly susceptible to ceftazidime (84.1%), chloramphenicol (82.6%), ciprofloxacin (72.7%), and marbofloxacin (72.2%). These findings highlight the high frequency of AMR in this population of clinically ill pet guinea pigs in Hong Kong and the need for informed and judicious antimicrobial use.