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Antimicrobial Resistance (AMR) Surveillance on Stool Culture in Public Hospitals and Clinics - Hospital Authority AMR Data (2021)

Release date: 1 February 2023

Method

Surveillance was conducted following the recommendations of the WHO GLASS Manual for Early Implementation (2015) with local adaptation as summarised below:

  • Two WHO priority organisms, namely Salmonella spp. and Shigella spp. were reported.
  • Location of onset would be collectively considered as “Community (undifferentiated)-onset” as a whole instead of adopting the definition by WHO (which defines specimens collected 2 calendar days after hospital admission as hospital-onset) as infections caused by these organisms are mostly community-associated and rarely are hospital-associated.
  • For each surveillance period (one calendar year), only the first result would be reported for each patient per specimen type per organism for the same location of onset.
  • Antimicrobial susceptibility test (AST) result being “Intermediate” or “Resistant” was considered “Non-susceptible”, while AST results derived from less than ten isolates per calendar year were excluded from the analysis.
  • To avoid misleading or interference by selection bias, percentages of non-susceptibility (NS%) derived from less than 70% of total isolates were not reported (or remarked to remind readers to interpret with caution).

Since the first Action Plan on AMR was published in 2017, the situation of 2016 has been chosen as the baseline for comparison. One-way Cochran-Armitage test was used to look for trends from 2016 to 2021. P-value of less than 0.05 was considered statistically significant.


Results

Overview of patients with stool culture

The total number of patients with stool culture collected increased from around 40,000 in 2020 to 44,000 in 2021 (10.0% increase). The percentage of patients with positive stool culture remained stable over the past years at around 10-11%.

Overview of WHO priority organisms isolated from stool (by applying WHO GLASS definition on location of onset)

The overall distribution of the two WHO priority organisms cultured from stool was similar since start of surveillance in 2016. The commonest organism isolated from stool in 2021 was Salmonella spp.

Antimicrobial susceptibility test results for WHO priority organisms


Salmonella spp.

Although an increasing trend was still seen for ampicillin (59.9%→70.4%), the NS% for ampicillin plateaued from 2019 to 2021. A statistically significant increasing trend towards ciprofloxacin (52.1%→56.9%) were observed.


Shigella spp.

Decreasing trends were seen for ampicillin (57.6%→41.7%) and co-trimoxazole (81.8%→58.3%). An increasing trend from year 2019 to 2021 towards ciprofloxacin (64.0%→75.0%) were observed. Yet such trends should be interpreted with caution due to the small sample size (<50 patients were tested annually).


Recommendations

In view of statistically significant increasing trend of non-susceptibility for isolates of Salmonella spp. towards ampicillin and ciprofloxacin and Shigella spp. towards ciprofloxacin, further monitoring would be warranted.


Acknowledgement

We would like to acknowledge stakeholders from HA, such as the Information Technology & Health Informatics Division, Quality and Safety Division, Strategy and Planning Division, and various Working Groups for the provision of input to facilitate the compilation of findings for the year 2021.

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