Antimicrobial Resistance (AMR) Surveillance on Urine Culture Specimen in Public Hospitals and Clinics - Hospital Authority AMR Data (2020)

Release date: 13 January 2022

Methodology

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

• Two WHO priority organisms, namely Escherichia coli and Klebsiella pneumoniae, were reported.
• Location of onset were classified as community-onset (CO) (organisms isolated from urine specimens collected in non-inpatient services, or within 48 hours after hospital admission) or hospital-onset (HO) (organisms isolated from urine specimen collected more than 48 hours after hospital admission).
• 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.
• AST result being “Intermediate” or “Resistant” was considered as “Non-susceptible”, while AST results derived from less than 10 isolates per calendar year were excluded from analysis.
• Only midstream urine specimens were included for analysis, and positive urine culture was defined as specimen with pure growth of organism reaching bacterial count which was equal to or greater than 10⁵ colony-forming units per millilitre (cfu/ml).
• To avoid misleading or interference by selection bias, percentages of non-susceptibility derived from less than 70% of total isolates were not reported (or remarked to remind readers to interpret with caution).

Where appropriate, AST results in relation to broad-spectrum antimicrobials identified by experts in HA (Big Guns) were examined because of their importance on treating resistant infections.

Since the Action Plan was published in 2017, the situation of 2016 has been chosen as the baseline for comparison.  Fisher’s exact test or chi-square test  was used to compare non-susceptibility percentages^[1] between year 2019 and 2020, whereas One-way Cochran-Armitage test was used to look for trend from year 2016 to 2020. P-value of less than 0.05 was considered as statistically significant.

Results

The total number of urine culture collected increased from around 290,000 in 2016 to around 313,000 in 2019 and then decreased to 293,000 in 2020.  Proportion of patients with urine culture collected from those aged 15-64 decreased gradually (51.1% to 49.3%) while from those aged 65 or above increased gradually (46.8% to 49.3%) from 2016 to 2020.  The percentage of patients with positive urine culture remained stable over the past years at around 15%.

The overall distribution of the two WHO priority organisms cultured from urine were similar during 2016 to 2020.  The commonest organism isolated from urine in 2020 was Escherichia coli, followed by “other spp.” and Klebsiella pneumoniae (isolated from 61.2%, 40.3% and 8.6% of patients with positive urine culture respectively).  Regarding location of onset, Escherichia coli and Klebsiella pneumonia were predominantly CO (86.0% and 83.2% respectively in 2020).

In general, non-susceptibility on majority of selected antimicrobials for the WHO priority organisms remained stable or showing decreasing trends which were statistically significant during year 2016 to 2020.  However, increasing trends of non-susceptibility percentage were also observed among several pathogen-antimicrobial combinations that may warrant further monitoring.

Escherichia coli

In general, non-susceptibility percentages were lower among E. coli isolates of CO than those of HO. The non-susceptibility percentages to amoxicillin/clavulanate and nitrofurantoin among Escherichia coli isolates of CO were at around 18% and 2%, while those of HO were at around 28% and 2% respectively in 2020.  Comparing between year 2019 and 2020, E. coli isolates of CO showed reduction in non-susceptibility percentage towards amoxicillin/clavulanate (20.7%→18.3%), co-trimoxazole (37.1%→34.8%) and nitrofurantoin (2.1%→1.8%), while there was an increase towards levofloxacin (40.3%→44.4%), which were all statistically significant.  No statistically significant changes in non-susceptibility percentage was observed among HO isolates.  Statistically significant decreasing trends in non-susceptibility percentages from year 2016 to 2020 were also observed towards amoxicillin/clavulanate (CO: 19.6%→18.3%), cefuroxime (oral) (CO: 50.7%→41.1%; HO: 61.0%→50.9%), co-trimoxazole (CO: 39.2%→34.8%; HO: 45.4%→43.9%) and nitrofurantoin (CO: 2.9%→1.8%; HO: 4.3%→1.7%).  On the contrary, statistically significant increasing trend from year 2016 to 2020 towards levofloxacin (CO: 34.8%→44.4%; HO: 42.6%→45.8%) was observed.

Klebsiella pneumoniae

Non-susceptibility percentages were generally lower among CO isolates than those of HO.  The non-susceptibility percentages to amoxicillin/clavulanate and nitrofurantoin among Klebsiella pneumoniae isolates of CO were at around 16% and 38%, while those of HO were at around 32% and 37% respectively in 2020.  Comparing between year 2019 and 2020, Klebsiella pneumonia isolates of CO showed reduction in non-susceptibility percentage towards amoxicillin/clavulanate (17.9%→15.9%) and cefuroxime (IV) (20.7%→18.0%), while there was an increase towards levofloxacin (16.0%→18.1%), which were all statistically significant.  No statistically significant changes in non-susceptibility was observed among HO isolates.  Trend analysis revealed statistically significant increasing trends from year 2016 to 2020 towards ceftazidime (HO: 20.9%→23.0%) and levofloxacin (CO: 11.1%→18.1%; HO: 18.4%→25.8%), while statistically significant decreasing trends were observed for cefuroxime (oral) (CO: 46.6%→36.1%), co-trimoxazole (HO: 37.0%→32.1%) and nitrofurantoin (CO: 49.9%→38.1%; HO: 54.2%→37.4%).

Trends in non-susceptibility percentages from year 2016 to 2020 with statistical significance mentioned above were summarised in the tables below.

Recommendations

In view of statistically significant increasing trend of non-susceptibility for Escherichia coli and Klebsiella pneumoniae towards levofloxacin (both CO and HO isolates) and Klebsiella pneumoniae towards ceftazidime (HO isolates only), further monitoring would be warranted.  We have alerted working partners of HA about increasing trend of non-susceptibility of the aforesaid antimicrobial-organism combinations for their further investigation and management as appropriate.

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Acknowledgement

We would like to acknowledge stakeholders from HA such as Information Technology & Health Informatics Division, Quality and Safety Division, Strategy and Planning Division, and various Working Groups for provision of input to facilitate compilation of findings for year 2020.

^[1]  Non-susceptibility percentage means the proportion of isolates tested for susceptibility of a particular antimicrobial, and with test result being non-susceptible.

^[2]  The following section illustrates some important drug-bug combinations.  Please refer to the powerpoint for full results. Data related to levofloxacin should be interpreted with caution because CLSI guidelines for sensitivity testing involving levofloxacin interpretive criteria for Enterobacteriaceae (except Salmonella spp.) has been updated in 2019.  For laboratories that chose to apply the new criteria for reporting in 2019, some E. coli and K. pneumoniae isolates previously categorised as susceptible to levofloxacin would be categorised as non-susceptible using the updated zone size requirement under the 2019 criteria.