Trends in antimicrobial resistance among Enterobacter isolates in an Australian local health district

BACKGROUND: Antimicrobial resistance (AMR) is a universal health issue, causing significant morbidity and mortality. Enterobacter species is a gram-negative bacterial pathogen that has intrinsic and acquired resistance to multiple antibiotic classes. AIM: To determine trends in antibiotic resistance among Enterobacter isolates in community and hospital settings within the Illawarra Shoalhaven region of NSW, Australia. METHODS: We analysed Enterobacter spp. isolates from a hospital-based (N = 2131) and a community-based (N = 1123) laboratory in Illawarra Shoalhaven, between 2007 and 2018. Trimethoprim, gentamicin, tobramycin, amikacin, ciprofloxacin, and meropenem resistance over the 11-y period was determined, and resistance trends and rates between community and hospital settings were compared, using statistical analysis (Pearson's chi-squared tests). FINDINGS: AMR was significantly higher in hospital (14.9%) compared to community (8.9%) isolates. AMR reduced over the 11-y period for all antibiotics except amikacin and meropenem, for which resistance remained low throughout. CONCLUSIONS: Antibiotic resistance in Enterobacter spp. was higher in the hospital setting; however, resistance over time either significantly reduced (for most antibiotics) or remained stable (for some antibiotics) in both groups. The reduction was more pronounced in the hospital setting. This highlights the contribution of hospital-based infection-control measures, including the antimicrobial stewardship program.