3.1.1 Escherichia coli bacteraemia

The number of Escherichia coli bacteraemias has been generally increasing since 2009 but decreased between 2021 and 2022 from 1478 to 1327 (Figure 3.1).

Between 2021 and 2022, the overall proportion of E. coli bacteraemias resistant to selected antibiotics increased from 16.7% to 17.2%.

Resistance to co-amoxiclav and third-generation cephalosporins remained stable (53.7% and 10.4% respectively). The proportion of isolates resistant to piperacillin/tazobactam (17.5% to 19%), gentamicin (8.3% to 10.9%) and ciprofloxacin (14.5% to 16%) increased slightly.

In 2022 one reported E. coli isolate was non-susceptible to carbapenems. This is a decrease from the three non-susceptible isolates detected in 2021. (Figure 3.2).

The proportion of E. coli bacteraemias showing multi-drug resistance decreased slightly between 2019 and 2021 (6% to 5.8%) before increasing in 2022 (6.5%). Within the combination of antibiotic classes, the highest proportion of non-susceptibility in 2022 was among third-generation cephalosporins, quinolones and aminglycosides (4.5%). This is a slight increase in comparison to 2021 during which 3.4% of E. coli were non-susceptible to third-generation cephalosporins, quinolones and aminoglycosides. The lowest proportion non-susceptible in 2022 was observed for third-generation cephalosporins, aminoglycosides and piperacillin/tazobactam (2.3%), although slightly increasing from 2021 (1.8%) (Figure 3.3).

3.1.2 Klebsiella pneumoniae bacteraemia

The number of Klebsiella pneumoniae bacteraemias has generally been increasing since 2009 but decreased slightly between 2021 and 2022 from 204 cases to 198 (Figure 3.4).

The overall proportion of K. pneumoniae bacteraemias non-susceptible to selected antibiotics decreased from 15.2% in 2021 to 14.8% in 2022. Specifically, resistance has decreased from 2021 to 2022 for: ciprofloxacin (16.3% to 13.8%), gentamicin (8.9% to 6.6%) and 3rd generation cephalosporin (14.5% to 12.3%).

Resistance to piperacillin/tazobactam increased from 25.2% in 2021 to 30.6% in 2022. Resistance to co-amoxiclav increased from 25.9% to 26.6% during the same time period. The number of isolates non-susceptible to carbapenems decreased between 2021 and 2022 from two non-susceptible isolates detected in 2021 to one detected in 2022 (Figure 3.5).

The proportion of K. pneumoniae bacteraemias showing multi-drug resistance remained stable within the named antibiotic combinations from 2021 to 2022 (8.7%). Within the named combinations of antibiotic classes, the highest proportion non-susceptible during 2021 to 2022 was observed among third-generation cephalosporins, quinolones and piperacillin/tazobactam. K. pneumoniae resistance to this combination decreased slightly from 6.0% in 2021 to 5.6% in 2022. The lowest proportion non-susceptible among the antibiotic class combinations was observed for aminglycosides, quinolones and piperacillin/tazobactam which decreased between 2021 to 2022 (4.5% to 3.1%) (Figure 3.6).

3.1.3 Klebsiella oxytoca bacteraemia

The number of Klebsiella oxytoca bacteraemias decreased sharply between 2021 and 2022, reducing from 106 isolates to 57 isolates. The number reported in 2022 is the lowest since 2013 when the same number were reported (Figure 3.7).

The overall proportion of K. oxytoca bacteraemias non-susceptible to selected antibiotics increased between 2021 (4.5%) and 2022 (8.3%).

K. oxytoca resistance to co-amoxiclav more than doubled between 2021 and 2022 (from 10.6% to 23.9%) and was similar to the proportion observed in 2020. Increases in resistance were also observed for ciprofloxacin (1% in 2021 to 5.4% in 2022) and piperacillin/tazobactam, increasing from 12.3% to 19.6% during the same time period. Within the combination of antibiotic classes, a decrease in resistance between 2021 and 2022 was observed among third-generation cephalosporins (3.8% to 1.8%). The number of K. oxytoca bacteraemias non-susceptible to gentamicin increased from zero to one between 2021 and 2022. There have been no carbapenem resistant K. oxytoca isolates reported to the PHA since 2011.

3.1.4 Pseudomonas species bacteraemia

The number of reported Pseudomonas species bacteraemias decreased from 111 in 2021 to 98 in 2022 (Figure 3.9).

The overall proportion of Pseudomonas species bacteraemias non-susceptible to selected antibiotics has increased from 2021 to 2022 (13.3% to 21.9%). Within the named antibiotic combinations, an increase in resistance amongst Pseudomonas isolates was noted for all key antibiotics during the 2021 to 2022 period. Resistance to 3rd generation cephalosporins increased from 16.4% to 26.9% during 2021 and 2022 along with resistance to ciprofloxacin (16.4% to 26%). The proportion of Pseudomonas species resistant to gentamicin increased from 1.9% to 3.6% between 2021 and 2022, while resistance to piperacillin/tazobactam increased from 18.2% to 32.3%.

The proportion of Pseudomonas species resistant to carbapenems increased from 13.6% to 18.8% between 2021 and 2022 (Figure 3.10).

3.1.5 Staphylococcus aureus bacteraemia

The number of Staphylococcus aureus bacteraemias reported to the PHA has been steadily increasing since 2014. Reported isolates decreased from 506 in 2021 to 393 in 2022 (Figure 3.11).

The proportion of S. aureus isolates non-susceptible to methicillin (MRSA) has steadily decreased from 2009 and remained low at 8.6% in 2021. A slight increase was however observed in 2022 (11.7%). S. aureus isolates non-susceptible to glycopeptides (eg. vancomycin or teicoplanin) decreased from one reported isolate in 2021 to zero in 2022.

3.1.6 Enterococcus species bacteraemia

The number of Enterococcus species bacteraemias has been generally increasing since 2009 although a decrease was observed between 2021 and 2022, from 312 reported isolates to 230 (Figure 3.13). The proportion of Enterococcus species bacteraemias non-susceptible to glycopeptides also decreased from 21.2% in 2021 to 17.5% in 2022 (Figure 3.14).

Amongst the two key Enterococcus species, resistance to teicoplanin and vancomycin decreased for both Enterococcus faecium and Enterococcus faecalis between 2021 and 2022.

No resistance to linezolid was detected among Enterococcus faecalis isolates during 2018 to 2022, however linezolid resistance amongst Enterococcus faecium isolates increased slightly from 0.68% to 0.85% between 2021 and 2022. Resistance to teicoplanin and vancomycin slightly decreased amongst Enterococcus faecalis isolates during 2021 and 2022 (2.78% to 2.04% and 2.8% to 2.04% respectively). A similar trend was observed with Enterococcus faecium resistance to teicoplanin reducing from 37.5% to 27.7% and resistance to vancomycin also decreasing from 37.5% to 27.5% during 2021 and 2022.

(Figure 3.15).

3.1.7 Streptococcus pneumoniae bacteraemia

The number of Streptococcus pneumoniae bacteraemias reported to PHA almost doubled between 2021 and 2022 (from 46 to 90 isolates) (Figure 3.16).

The proportion of S. pneumoniae non-susceptible to macrolides increased from 5% in 2021 to 10.3% in 2022 while the proportion non-susceptible to penicillin decreased over the same time period (from 19.6% in 2021 to 13% in 2022) (Figure 3.17).

3.1.8 Acinetobacter species bacteraemia

The number of Acinetobacter species bacteraemias reported to PHA slightly increased from 24 cases in 2021 to 28 in 2022 (Figure 3.18). There have been no Acinetobacter species isolates non-susceptible to colistin reported since 2017 (Figure 3.19).

There have been no reports of colistin resistance amongst K. oxytoca, E. coli, S. aureus, K. pneumoniae , S. pneumoniae and Enterococcus species bacteraemias between 2009 and 2022.

3.1.9 Carbapenamase-Producing Enterobacterales

The number of carbapenamase-producing Enterobacterales (CPE) voluntarily reported to the PHA increased from 5 isolates in 2021 to 18 isolates in 2022. The number reported in 2022 is similar to that observed in 2014 and 2015 (Figure 3.20).

In 2022, the most commonly reported mechanism of carbapenem resistance was Imipenemase producers (IMP) with 5 reported episodes, followed by OXA-48 (4 episodes), Klebsiella pneumoniae carbapenemase (KPC) and Verona integron-encoded Metallo-β-lactamase (VIM) with 3 episodes each. There was one reported New Delhi Metallo-β-lactamase (NDM) in 2022. In 2021, NDM and OXA-48 were the most commonly reported resistance mechanisms (2 episodes each), with one report of KPC. There were no reports of IMP in 2021.

The most commonly reported CPE organisms during 2022 were Enterobacter cloacae and Escherichia coli (5 episodes each), compared with Klebsiella spp. (3 episodes) in 2021 (Figure 3.21).

3.1.10 Antibiotic resistance in Neisseria gonorrhoeae

Gonorrhoea has been identified as at risk of becoming an untreatable disease due to the emergence of resistance to successive standard treatments [5]. This has necessitated changes to recommended antibiotic prescribing. In the UK, current recommended treatment guidelines include the extended spectrum cephalosporin (ESC), ceftriaxone, along with routine test of cure [6]. Azithromycin is no longer recommended as co-treatment. Third-generation cephalosporins are the last remaining effective antibiotics but reports of treatment failures and increasing minimum inhibitory concentrations (MIC) levels have raised concerns that they will no longer be a suitable treatment option [7].PHA submit N. gonorrhoeae antimicrobial susceptibility information directly to the WHO GLASS (Global Antimicrobial Resistance and Use Surveillance System) programme [8].

During 2022, 1,606 Neisseria gonorrhoeae diagnoses were made in Genitourinary Medicine (GUM) clinics in Northern Ireland. This is an almost three-fold increase in Neisseria gonorrhoeae diagnoses in comparison to 2021, when 652 diagnoses were made. In 2022, 293 patients’ samples were cultured and tested for antibiotic susceptibility against azithromycin, ceftriaxone and/or ciprofloxacin. No isolates were resistant to ceftriaxone, 33.4% were resistant to ciprofloxacin and 12.5% to azithromycin.

3.2.1 Rates of antibiotic consumption by healthcare setting

The total consumption of all antibiotics increased from 25.87 DDD per 1000 inhabitants per day in 2021 to 30.42 DDD per 1000 inhabitants per day in 2022.

While primary care has remained the highest prescriber of antibiotics, the proportion of total consumption accounted for by this sector continued to decline from 81.3% in 2014 to 77% in 2021. A slight increase was observed in 2022 with 79.6% of total prescribing accounting for primary care. The proportion of total antibiotic consumption accounted for by dental settings remained relatively low from 2014 (4.6%) before an increase to 7.2% in 2020. From 2021 onwards, antibiotic prescribing in dental care has continued to steadily decrease to 6.6% of total prescribing in 2021 and a further decrease to 5.2% in 2022. Out-of-hours consumption remained relatively stable in 2020 and 2021 ( 0.7% and 0.8% of total prescribing) before slightly increasing to 1% in 2022.

The proportion of total antibiotic consumption accounted for by secondary care decreased slightly from 15.6% in 2021 to 14.2% in 2022 (Figure 3.22).

Antibiotic consumption in primary care increased between 2021 and 2022 from 19.92 to 24.23 DDDs per 1000 inhabitants per day. The secondary care antibiotic consumption rate also increased slightly during the same time period (4.04 to 4.31 DDDs per 1000 inhabitants per day). Dental prescribing rates decreased from 1.71 DDDs per 1000 inhabitants per day in 2021 to 1.58 in 2022. Out of hours prescribing rates have continued to increase from 2020 (0.16 DDDs per 1000 inhabitants per day), almost doubling to 0.31 DDDs per 1000 inhabitants per day in 2022.

Rates of antibiotic consumption in Secondary care

There has been a general increase in the rate of secondary care antibiotic consumption expressed as DDD per 1000 admissions between 2021 and 2022, with the rate increasing from 11296 DDDs per 1000 admissions in 2021 to 11963 DDDs per 1000 admissions in 2022. (Figure 3.23).

The secondary care antibiotic consumption rate per 1000 occupied bed days decreased between 2021-2022 from 1718 to 1671 DDD per 1000 occupied bed days. (Figure 3.24).

Figure 3.25 shows the top 6 antibiotics prescribed in secondary care. In 2022, the highest rates of antibiotic consumption were for penicillins which increased from 2259 DDDs per 1000 admissions in 2021 to 2542 in 2022.Penicillin/beta lactamase inhibitor combinations have increased from 1843 to 2033 DDD per 1000 admissions. Anti-tuberculosis drugs decreased from 1749 to 1701 DDDs per 1000 admissions during 2021-2022, while the use of tetracyclines and related drugs have increased from 1403 to 1430 DDD per 1000 admissions between 2021 and 2022.

3.2.2 Antibiotic consumption by key agents

During 2022, the most frequently used antibiotics in both primary and secondary care in NI were penicillins (40.5% and 21.3% respectively), followed by tetracyclines and related drugs (27.9% and 12% respectively). This is similar to the trends observed in 2021 when penicillins were also the most frequently consumed antibiotic class in both primary and secondary care (37.2% and 20% respectively) (Figure 3.26).

Note: Oral/rectal preparations for metronidazole (ATC P01AB01) and vancomycin (ATC A07AA09) are included in the anti-clostridium difficile agents and do not appear in the nitroimidazoles or glycopeptides categories respectively.

Note: differing scales on y-axis.

3.2.3 Antibiotic consumption by class and individual antibiotics

Penicillins

Figure 3.27 shows the top six antimicrobial agents used in the penicillins class. Penicillins accounted for 37.8% of total antibiotic consumption in 2022.

Penicillin consumption decreased from 10.53 DDD per 1000 inhabitants per day in 2018 to 8.94 in 2021. The rate of consumption increased to 11.50 DDD per 1000 inhabitants per day in 2022. This is the highest rate observed since 2014. The highest rate among antibiotics within the penicillins class was for amoxicillin, which had steadily decreased between 2018-2021 (7.38 to 5.94 DDD per 1000 inhabitants per day), but increased to 8.06 DDD per 1000 inhabitants per day in 2022.

Cephalosporins

Figure 3.28 displays the top six agents used in the cephalosporins class. The overall rate of cephalosporin consumption remained relatively stable between 2018 and 2021 (0.51 to 0.55 DDD per 1000 inhabitants per day). Total cephalosporin consumption continued to remain relatively stable in 2022 at 0.57 DDD per 1000 inhabitants per day.

The highest rate among antibiotics in the cephalosporins class was for cefalexin, which also remained relatively stable between 2018 and 2022 (0.4 to 0.46 DDD per 1000 inhabitants per day).

Tetracyclines and related drugs

Figure 3.29 shows the top six agents used in the tetracyclines and related drugs class. The proportion of total antibiotic consumption accounted for by tetracyclines and related drugs has remained relatively stable between 2021 and 2022 (26.1 and 25.6%).

Consumption of tetracyclines and related drugs decreased between 2018 and 2021 (from 7.35 to 6.76 DDD per 1000 inhabitants per day) with an increase observed in 2022 (7.80 DDD per 1000 inhabitants per day). This is the highest rate observed since 2014.

Within the tetracyclines and related drugs class, the highest usage rate was for doxycycline, which increased between 2021 and 2022 (from 4.66 to 5.87 DDD per 1000 inhabitants per day).

Note: While demeclocycline and lymecycline are not primarily used for their antimicrobial effects they have been included as they can still be considered drivers of resistance.

Quinolones

Consumption of quinolones steadily decreased from 0.66 DDD per 1000 inhabitants per day in 2018 to 0.46 DDD per 1000 inhabitants per day in 2021, remaining stable in 2022. Within the quinolones class, the highest consumption rate was for ciprofloxacin. Ciprofloxacin consumption also decreased from 2018 (0.54 DDD per 1000 inhabitants per day) to 0.36 DDD per 1000 inhabitants per day in 2021, remaining stable in 2022 (Figure 3.30).

Macrolides

Macrolides accounted for 10.4% of total antibiotic consumption in 2022. Despite the proportion of total antibiotic consumption remaining stable between 2021 and 2022, consumption of macrolides increased from 2.73 DDDs per 1000 inhabitants per day in 2021 to 3.17 DDDs per 1000 inhabitants per day in 2022.

Within the macrolide class the highest usage was for clarithromycin, for which consumption slightly increased between 2021 and 2022 (1.5 DDD per 1000 inhabitants per day in 2021 and 1.94 DDD per 1000 inhabitants per day in 2022). Despite this increase clarithromycin consumption has remained below 2019 levels (2.18 DDD per 1000 inhabitants per day) (Figure 3.31).

Carbapenems

The rate of carbapenem consumption remained low and relatively stable from 2018 to 2022 (0.06 DDD per 1000 inhabitants per day in 2018 to 0.05 DDD per 1000 inhabitants per day in 2022). The highest consumption rate within the carbapenem class was for meropenem, which has remained stable since 2019 at 0.04 DDD per 1000 inhabitants per day (Figure 3.32).

Penicillin/beta lactamase inhibitor combinations

Consumption of penicillin/beta lactamase inhibitor combinations has increased between 2018 and 2022. During the 2018-2021 period the consumption rate increased from 1.83 to 1.97 DDD per 1000 inhabitants per day. The rate increased further in 2022 to 2.28 DDD per 1000 inhabitants per day.

The highest consumption rate within the class was for co-amoxiclav which followed a similar trend to the penicillin/beta lactamase inhibitor combinations class overall, increasing from 1.64 in 2018 to 2.09 DDD per 1000 inhabitants per day in 2022.

The use of piperacillin/tazobactam has remained relatively stable during 2018-2022 with rates remaining below 0.20 DDD per 1000 inhabitants per day (Figure 3.33).

Glycopeptides and daptomycin

Glycopeptides and daptomycin consumption remained relatively stable between 2018 and 2022 at 0.18 and 0.20 DDD per 1000 inhabitants per day respectively. The highest consumption rate within the class was for teicoplanin, which followed a similar trend to glycopeptide and daptomycin consumption overall. Teicoplanin use has remained stable between 2018-2022, increasing very slightly from 0.14 in 2018 to 0.16 DDD per 1000 inhabitants per day in 2022 (Figure 3.34).

Anti-folate agents

Anti-folate agents accounted for 8.6% of total antibiotic consumption in 2022 which is a decrease from the 9.4% in 2021. The consumption rate of anti-folate agents had been steadily declining between 2018 and 2021 but increased slightly from 2.43 DDD per 1000 inhabitants per day in 2021 to 2.61 DDD per 1000 inhabitants per day in 2022.

The highest consumption rate within the class during 2021 and 2022 was for nitrofurantoin. Nitrofurantoin use slightly decreased between 2018 to 2020 from 1.13 to 1.04 DDDs per 1000 inhabitants per day, prior to increasing to 1.18 in 2022. Prior to 2021, the highest consumption rate within the anti-folate agent class was for trimethoprim (Figure 3.35).

3.2.4 Antibiotic consumption of key agents by healthcare setting

Trimethoprim

Trimethoprim use in primary and secondary care combined continued to decrease from 1.31 DDD per 1000 inhabitants per day in 2018 to 0.99 DDD per 1000 inhabitants per day in 2022.

Consumption of trimethoprim was stable between 2018 to 2019 (1.2 DDD per 1000 inhabitants per day in primary care and 0.1 DDD per 1000 inhabitants per day in secondary care) prior to a slight decrease across both sectors in 2020 (1.01 DDD per 1000 inhabitants per day and 0.07 DDD per 1000 inhabitants per day respectively). In primary care, trimethoprim use decreased further in 2021 to 0.93 DDD per 1000 inhabitants per day, while secondary care use remained unchanged (0.07 DDD per 1000 inhabitants per day). In 2022, trimethoprim consumption remained relatively stable in both primary (0.92 DDD per 1000 inhabitants) and secondary care (0.07 DDD per 1000 inhabitants) (Figure 3.36).

Nitrofurantoin

Consumption of nitrofurantoin in primary and secondary care combined increased between 2021 and 2022 (1.10 to 1.18 DDD per 1000 inhabitants per day) and was the highest rate observed since 2016 (1.23 DDD per 1000 inhabitants per day).

Nitrofurantoin use displayed a similar pattern across the sectors, with a decrease noted from 2018 (1.03 DDD per 1000 inhabitants per day in primary care and 0.09 in secondary care) to 2020 (0.96 and 0.08 DDD per 1000 inhabitants per day respectively). In 2021, a slight increase in nitrofurantoin use was noted in both sectors, to 1.01 DDD per 1000 inhabitants per day in primary care and 0.10 DDD per 1000 inhabitants per day in secondary care. Nitrofurantion use in primary care increased slightly further in 2022 (1.08 DDD per 1000 inhabitants per day) but remained stable in secondary care (Figure 3.36).

Aminoglycosides

Aminoglycosides were used predominantly in the secondary care sector. Consumption of aminoglycosides in secondary care was stable between 2017-2019 at 0.17 DDD per 1000 inhabitants per day, before decreasing slightly to 0.14 in 2020 and holding stable in 2021. Aminoglycoside use in 2022 decreased slightly to 0.13 DDD per 1000 inhabitants per day (Figure 3.36).

Glycopeptides and daptomycin

Glycopeptides and daptomycin were also used predominantly in the secondary care sector. Glycopeptides and daptomycin use in secondary care was generally stable between 2018 and 2021 at 0.18 DDD per 1000 inhabitants per day. A slight decrease was noted in the consumption of glycopeptides and daptomycin in secondary care during 2022 (0.20 DDD per 1000 inhabitants per day) (Figure 3.36).

Colistin

Colistin use in primary and secondary care combined slightly increased between 2014 and 2020 (0.10 to 0.14 DDD per 1000 inhabitants per day) and remained stable during 2021 and 2022.

Rates of colistin consumption in primary care increased from 0.10 in 2018 to 0.13 DDD per 1000 inhabitants per day in 2020, followed by a slight decrease in 2021 (to 0.12 DDD per 1000 inhabitants per day) before increasing again in 2022 (0.13 DDD per 1000 inhabitants per day). Colistin use within secondary care remained unchanged between 2018 and 2020 (0.02 DDD per 1000 inhabitants per day), followed by a slight decrease to 0.01 DDD per 1000 inhabitants per day in 2021, remaining stable in 2022 (Figure 3.36).

Note: differing scales on y-axis. DDDs in primary care for aminoglycosides and glycopeptides/daptomycin are not truly zero.

3.2.5 Antibiotic consumption by WHO AWaRe Category

The World Health Organization (WHO) classifies antibiotics into three stewardship groups known as the AWaRe categories; Access, Watch and Reserve. Antibiotics in the Access group include antibiotics that can be used for a range of common susceptible pathogens and have a lower potential for resistance. The Watch group contains those with an increased potential for resistance and should be used in a restricted manner and includes most high priority agents. The Reserve group contains antibiotics which are to be treated as ‘last resort’ when other treatments have failed or there are no alternatives available. Adapted WHO AWaRe categories are used in NI with several national and trust level antibiotic consumption targets based on these which will stand for the remainder of the current target period (2019-2024).

The highest proportion of total antibiotic consumption during each year covered by this report was from antibiotics within the Access category, which increased across the period 2018-2022 (65.49% to 69.14%).

The proportion of total consumption accounted for by antibiotics from the Watch group has decreased during the same time period from 33.57% in 2018 to 29.36% in 2022. Consumption of antibiotics from the Reserve category has increased between 2018 and 2020 (0.82% to 1.01%) before a slight decrease in 2022(0.88%). Antibiotics not assigned to any of the AWaRe categories- denoted here as ‘unknown’- accounted for less than 0.63% of total consumption in each year between 2018 and 2022 (Figure 3.37).

Note: the chart above does not include antibiotics used for the treatment of tuberculosis. Please see appendix 2 for details of antibiotics used for the treatment of tuberculosis

3.4.1 Future work

Planned future work will include:

• Contributing to the development of the new UK National Action Plan for antimicrobial resistance and the development of a local implementation plan for NI.

• Continued provision of prescribing trend information to primary and secondary care prescribers.

• Further refinement of secondary care data capture and reporting processes to allow more timely and comprehensive information to help focus and reduce antibiotic use in secondary care services.

• Implementing the Pharmacy First Pilot Service for Uncomplicated Lower Urinary Tract Infections (LUTIs) in community pharmacies.

• Continued engagement in awareness activities during the European Antibiotic Awareness Day (EEAD) and World Antibiotic Awareness Week (WAAW).

5.1.1 Data sources

Testing for bacteria in human specimens and their susceptibility to antibiotics is conducted in the laboratories of five Health and Social Care Trusts in NI. Infections that meet certain criteria, usually the most severe that occur in the blood (bacteraemias), are reported voluntarily to the PHA’s “NILIS” Information System directly from each Trust’s laboratory. The resistance data included in this report includes selected bacteraemias that were reported to the PHA between 2009 - 2021 (presented by calendar year).

Detections of carbapenemase-producing organisms (CPOs) are reported to the PHA as part of a voluntary reporting service. In cases where a microbiology laboratory suspects a CPO, the specimen is submitted to UK Health Security Agency’s (UKHSA) Antimicrobial Resistance and Healthcare Associated Infections (AMRHAI) reference unit for investigation. Most recently, some health and social care trusts have developed the capacity to perform this function locally. For the purposes of this report however, the focus will be on carbapenemase-producing Enterobacterales (CPE) only.

5.1.2 Definitions

The term “antimicrobial” refers to drugs used to treat infections caused by a range of microbes including; bacteria, viruses, fungi and parasites. While this term is used throughout the report, the data presented only reflects antibiotics which are used to treat bacterial infections.

Hospital microbiology laboratories report antimicrobial susceptibility test results as “susceptible”, “intermediate” or “resistant”. For the purpose of this report, antibiotic susceptibility test results reported as “intermediate” or “resistant” were combined and presented as “non-susceptible”. The terms “non-susceptible” and “resistant” are used interchangeably throughout the report when referring to “intermediate” or “resistant” antibiotic susceptibility tests. For analysis of resistance to more than one antibiotic, multi-drug resistance (MDR) was defined as acquired non-susceptibility to at least one agent in three or more antimicrobial classes.

5.2.1 Data sources

Primary care antibiotic consumption data was extracted from the Enhanced Prescribing Database by the Health and Social Care Board. The data includes health and social care prescribing from: general practitioners within general practice and out-of-hours centres; nurse, pharmacy and allied health professionals; and, dentists. The secondary care antibiotic consumption data were extracted by each Trust’s JAC Medicines Management System and aggregated for all five Trusts to give Northern Ireland totals. It was not possible to analyse at the level of inpatient or outpatient. The data for all settings are available from 2014-2022 and are presented by calendar year.

Different to in England, outpatient medications in NI are usually prescribed by general practitioners at the request of secondary care specialists. A significant proportion of outpatient prescribing is therefore counted under primary care in NI as opposed to secondary care in England. There is currently no way of separating these prescriptions from the rest of primary care prescribing in NI. In England, outpatient prescribing accounts for 6.5% of secondary care antimicrobial prescribing [13].

Data from out-of-hours settings was extracted from multiple sources. For pre-packed antibiotics the JAC Medicines Management System and a private pharmaceutical company are responsible for over-labelling of antibiotic packs. All other out-of-hours data is received from the BSO Pharmaceutical Payment System.

5.2.2 Definitions

The classification of antibiotic used is based on the anatomical therapeutic chemical (ATC) classification system, using the WHO defined daily doses (DDD) for each drug and where grouped, this has been done according to Kucer’s “The Use of Antibiotics” (6th edition) [14]. The data for both settings in this report include ATC classification groups J01, A07 and P01, please refer to Appendix 2 for specific inclusions.

5.2.3 Denominator

Mid-year population estimates were obtained from the (NI Statistics and Research Agency) using the June 2023 rebased figures to express DDD’s per 1,000 inhabitants per day. Hospital activity and occupancy statistics were obtained from data published by the Department of Health.

5.2.4 WHO Defined Daily Doses

Antibiotic consumption is measured here using the 2019 WHO Classification of Defined Daily Doses (DDDs). The World Health Organization updates the DDDs on a semi-regular basis and these changes are applied to data retrospectively [15].