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Antimicrobial Resistance (AMR) Surveillance on Blood 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:

  • Six WHO priority organisms, namely Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Salmonella species (spp.), Acinetobacter spp. and Streptococcus pneumoniae were reported.
  • Location of onset was classified as community-onset (CO) (organism isolated from blood specimen collected in non-inpatient services or within 48 hours after hospital admission) or hospital-onset (HO) (organism isolated from blood specimen collected more than 48 hours after hospital admission). As Salmonella spp. and Streptococcus pneumoniae rarely cause hospital-associated infections, related antimicrobial susceptibility test (AST) results were interpreted as “community (undifferentiated) onset”.
  • 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 “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[1] (NS%) derived from less than 70% of total isolates were not reported (or remarked to remind readers to interpret the findings with caution).
  • Positive cultures for the same organism within 14 days from the same patient would be regarded as a single episode even if the first was of CO while the second or the rest were of HO (“Day-14” rule).

Where appropriate, AST results for broad-spectrum antimicrobials identified by experts in HA (“Big Guns”) were examined because of their importance in treating resistant infections. For Salmonella spp. and Streptococcus pneumoniae, since infections caused by these organisms are usually treated by first-line antimicrobials, NS% of respective first-line antimicrobials were reported.

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 blood culture

The Number of patients with blood culture remained similar in 2020 and 2021 at about 140,000. Amongst patients with blood culture collected each year, over 50% were aged 65 years or above. The percentage of patients with positive blood culture remained stable from 2016 to 2021 (around 10-11%).

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

The overall distribution of the six WHO priority organisms cultured from blood was similar from 2016 to 2021, with the three commonest organisms in 2020 being Escherichia coli, Klebsiella pneumoniae and Staphylococcus aureus (isolated from 39.5%, 13.3% and 11.6% of patients with positive blood culture respectively). The number of patients with Salmonella spp. isolated from blood reduced from about 300 in 2020 to 200 in 2021. The case count for Streptococcus pneumoniae (<50 cases) and Acinetobacter spp. (about 200 cases) remained low and stable. Regarding the location of onset, Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Salmonella spp. and Streptococcus pneumoniae were predominantly CO, while Acinetobacter spp. was predominantly HO.

In general, continual downward trends on non-susceptibility on some antimicrobials for the WHO priority organisms were observed in 2021. However, newly seen upward trend of NS% on carbapenems for Escherichia coli and Klebsiella pneumoniae were observed, which warrants further monitoring.  Below summarises the overall pattern of non-susceptibility on antimicrobials as of end-2021.

Antimicrobial susceptibility test results for WHO priority organisms


Escherichia coli

In 2021, continuous downward trends were observed for piperacillin/ tazobactam (CO: 7.2%→4.2%; HO: 14.1%→10.3%), ceftazidime (HO: 23.2%→18.4%), cefepime (CO: 23.6%→15.4%; HO: 33.1%→19.8%) and gentamicin (CO: 28.9%→23.5% & HO: 35.3%→29.2%) when compared with baseline in 2016. For community-onset Escherichia coli bacteraemia, although an increasing trend was still seen for amoxicillin/ clavulanate (27.1%→27.3%), cefotaxime (27.8%→28.9%), cefuroxime (30.1%→31.4%), a mild reduction was also observed. At the same time, the NS% for ertapenem (CO: 0.1%→0.2%) and imipenem (HO: 0.2%→1.6%) showed an increasing trend for the first time since the beginning of surveillance (2016-2021).


Klebsiella pneumoniae

A decreasing trend for cefepime (CO: 8.4%→5.6%), gentamicin (HO: 14.6%→11.9%) and piperacillin/ tazobactam (HO: 21.5%→14.9%) were observed in 16-21. The NS% for gentamicin (CO: 5.5%→4.6%) and cefepime (HO: 20.3%→16.4%) showed a decreasing trend for the first time since the beginning of surveillance (16-21). Although an increasing trend was still seen for amoxicillin/ clavulanate (CO: 13.9%→15.9%) and meropenem (HO: 1.2%→4.3%), a mild reduction of NS% in 2021 was also observed. On the other hand, NS% for ertapenem (HO: 2.9%→4.9%) and imipenem (HO: 1.3%→6.7%) showed an increasing trend, of which a rising trend for ertapenem was firstly seen since the beginning of surveillance (2016-2021).


Staphylococcus aureus

No significant change in trend was observed for Staphylococcus aureus isolated from blood. NS% for oxacillin[2] remains at 40% for CO isolates and 60% for HO isolates from 2016 to 2021.


Salmonella species

Although an increasing trend continued for ampicillin non-susceptibility (62.4%→66%), but a mild reduction was observed in 2021. On the other hand, the NS% of ceftriaxone (6.2%→6.4%) increased in 2021 in contrast to the decreasing trend observed from 2016-2020.


Acinetobacter species

Increasing trends were observed in 2016-2020 for amikacin (HO: 21.5%→29.9%), ampicillin/ sulbactam (HO: 52.5%→59.1%), gentamicin (HO: 27.9%→36.5%), imipenem (HO: 60.2%→62.6%) and meropenem (HO: 59%→67.9%) remained in 2016-2021.Nevertheless, the NS% in 2021 of these drugs were lower than that of 2020.


Streptococcus pneumoniae

Continuous upward trends were observed for cefotaxime (0.9%→5.3%) and penicillin (0.7%→14.3% for 16-20, 0% in the year 2021) for 16-21. However, such trends should be interpreted with caution due to the small sample size.


Recommendations

The NS% on selected drug-bug combinations started to decrease in 2021 when compared to the 2020 (such as Acinetobacter spp., Amoxicillin/ clavulanate for community-onset Escherichia coli and Klebsiella pneumoniae bacteraemia). Antibiotic Stewardship Programme (ASP) in public hospitals should be continued and promoted, aiming to optimize the use of antibiotics by providing evidence-based antibiotic prescription guidance for common infections. (Objective 6 of the Hong Kong Strategy and Action Plan on AMR 2023-2027), Meanwhile, attention should be paid to emerging drug-bug combinations that showed increasing resistance against especially, the “Big Guns” such as:

  • Escherichia coli – ertapenem (community-onset bacteraemia) & imipenem (hospital-onset bacteraemia)
  • Klebsiella pneumoniae – ertapenem (hospital-onset bacteraemia)


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

[2]  Sensitivity testing results of penicillinase stable penicillins (oxacillin, cloxacillin and methicillin) and cefoxitin towards Staphylococcus aureus were collectively grouped as “oxacillin” following the recommendation of CLSI.