Antimicrobial resistance in Pseudomonas aeruginosa bacteraemia, percent of resistance by month
Last updated on Thursday, 12 June 2025 at 10:08am
Summary
- Topic
- P-aeruginosa
- Category
- testing
- API name
p-aeruginosa_testing_bacteraemiaPercentResistantRollingMonth
Rationale
Timely monitoring of susceptibility test results for Pseudomonas aeruginosa (P. aeruginosa) supports the government’s 5-year action plan on confronting antimicrobial resistance (AMR; for example, resistance to antibiotics). Antimicrobials presented in this metric have been selected due to their clinical importance when treating serious P. aeruginosa infections.
Definition
This metric shows the rolling monthly average of the percentage of P. aeruginosa bacteraemia (bacteria found in patient blood specimens), reported by English laboratories, with resistant test results for ciprofloxacin, piperacillin with tazobactam, amikacin, carbapenems or ceftazidime.
Methodology
A national database maintained by UKHSA (the AMR module of SGSS – Second Generation Surveillance System) contains voluntary laboratory data from approximately 98% of hospital microbiology laboratories in England. Data on susceptibility of pathogens was obtained from SGSS for this metric. Patients may have more than one positive culture (type of laboratory test undertaken on blood specimens) result reported to SGSS, so cultures from the same patient for the same pathogen in a 14-day rolling period are deduplicated to only retain one result representing that episode of bacteraemia per patient. If the susceptibility results for the different cultures are different, a worst-case scenario methodology is applied, retaining the most resistant result (“resistant” is retained over “susceptible, increased exposure”, which is retained over “susceptible”) for that infection episode. Susceptibility categories are defined per the European Committee on Antimicrobial Susceptibility Testing.
This metric is calculated by dividing the number of P. aeruginosa bacteraemia episodes with susceptibility test results by the number of P. aeruginosa bacteraemia episodes with resistant test results for ciprofloxacin, piperacillin with tazobactam, amikacin, carbapenems or ceftazidime by month, and averaging the result for each month with over the previous two months, to create a three-month rolling average. Results are multiplied by 100 to be viewed as a percentage.
Carbapenems comprise meropenem or imipenem.
Caveats
Combining patient results into one infection episode is limited by the provision of key identifiers by reporting laboratories, so some episodes may be counted more than once if these identifiers enabling grouping and de-duplication are not provided or are provided incorrectly.
The data reflects microbiology results reported to the UK Health Security Agency's routine laboratory surveillance system antimicrobial testing module (SGSS AMR;). Not all laboratories in England were able to report during the indicator time period, and not all laboratories test the same panels of antimicrobials, which can vary depending on local prescribing practices. As a result, a zero value does not necessarily reflect a lack of resistance but could reflect a lack of testing for that particular antimicrobial, or a lack of reporting in an area. Review of this indicator alongside the comparable testing indicator will facilitate interpretation.
Hospital microbiology laboratories have reported antimicrobial susceptibility test results as ‘susceptible’,’susceptible, increased exposure’ or ‘resistant’. These categories were defined as follows as per the European Committee on Antimicrobial Susceptibility Testing (EUCAST). Breakpoints can change over time, and this has implications for interpretation of resistance trends spanning breakpoint changes; please see ESPAUR 2023/24 report box 2.3 for further information.
For the whole time period, values are presented with only resistant episodes included in the numerator, as per the definition of susceptibility test results used by the European Committee on Antimicrobial Susceptibility Testing (EUCAST), updated in January 2019.
SGSS is a live reporting database, and therefore data is subject to change and may differ from other published outputs.