Research and analysis

Carbapenemase-producing Gram-negative organisms in England since October 2020: quarterly update, Q4 2024

Updated 31 March 2025

Applies to England

Main messages

Main messages from this report are that:

• between October 2020 and December 2024, there were 20,544 acquired carbapenemase-producing organism (CPO) episodes reported to UKHSA – the majority were identified in screening samples, accounting for 71.7% of notifications, with 910 (4.4%) reported from sterile site specimens

• the quarterly rate of reported CPO episodes in quarter 4 (Q4) 2024 (3.3 per 100,000 population) decreased from Q3 2024 (3.7 per 100,000 population), which was the highest since mandatory reporting began in Q4 2020 – this was largely due to a decrease in reports of CPO from screening specimens in London, the North East, and the North West in this period (a decrease of 13.4%, 41.6%, and 24.8%, respectively)

• reporting of CPO specimens from sterile site increased from 82 in Q3 2024 to 89 in Q4 2024, with the latest 2 quarters seeing the highest numbers of positive sterile site specimens reported since mandatory surveillance began

• the highest rate of CPO continues to be in London and the North West (26.2 and 22.7 per 100,000 population, respectively) – this report now provides ICB breakdown, with NHS North West London ICB having the highest rate (40.2 per 100,000 population) and NHS Gloucestershire ICB having the lowest (0.8 per 100,000 population)

• the most reported acquired carbapenemase in the last year (Q1 2024 to Q4 2024) was NDM (35.9%), followed by OXA-48-like (34.4%) and KPC (19.6%); however, this varied by region – in London, the East Midlands and the South East, NDM was the most reported mechanism, OXA-48-like was the most reported mechanism in the East of England and the West Midlands, whereas KPC dominated reports in the North West

• no changes occurred in CPO distribution across demographic groups (age and sex, ethnic group and index of multiple deprivation (IMD) decile) since the last report

Background

Since 1 October 2020, all diagnostic laboratories in England have a duty to notify the following via UKHSA’s Second Generation Surveillance System (SGSS) (1):

• acquired carbapenemase-producing Gram-negative bacteria identified in human samples
• the results of any antimicrobial susceptibility test and carbapenem resistance mechanism in any of the causative agents listed in Schedule 2 of the Health Protection (Notifications) Regulations 2010

This requirement was launched in conjunction with the national Framework of actions to contain carbapenemase-producing Enterobacterales (CPE), which sets out a range of measures that, if implemented well, can help health and social care providers minimise the impact of carbapenemase-producing organisms (CPOs).

The analyses below are based on data relating to notifications of confirmed acquired CPOs between 1 October 2020 and 31 December 2024 in England. The data was extracted on 14 February 2025 from both UKHSA’s voluntary surveillance database, SGSS, and the Antimicrobial Resistance and Healthcare-Associated Infections (AMRHAI) Reference Unit database.

Both annual and quarterly rates of acquired CPOs were calculated using mid-year resident population estimates for the respective year and geography. Geographical analyses were based on the patient’s residential postcode; where this information was unknown, the postcode of the reporting laboratory was used. Cases in England were further assigned to one of 9 local areas and one of 42 integrated care boards (ICBs), formed from the administrative local authority boundaries and Office for National Statistics ICB boundaries. The annual rates of acquired CPOs by geographical region included in this report differ slightly from those calculated in some previous reports due to a methodological adjustment following the identification of an inconsistency in previous reports’ methodology. Previous reports will be corrected accordingly.

Samples are split into 3 specimen types: sterile site specimens (for example blood or cerebrospinal fluid), screening site specimens (for example faeces or lower gastrointestinal tract) or ‘other’ specimen type (for example urine or lower genital tract). In order to count patients per year with a CPO, and as patients may have more than one positive specimen taken, specimens taken from the same patient that yielded growth of the same bacterial species, had the same carbapenemase gene and were from the same specimen type within a 52-week period from the initial positive specimen were regarded as comprising the same episode and were de-duplicated. CPO isolates referred to the AMRHAI Reference Unit and local laboratory isolates were combined for this de-duplication process, with resistance mechanism results from the AMRHAI Reference Unit retained preferentially where patient specimen overlap occurred (please note, not all specimens in this report are confirmed by the AMRHAI Reference Unit). This method differs slightly from the weekly causative agent notification data, where data is not de-duplicated incorporating specimen type. In addition, the data presented in the weekly notification reports is utilising SGSS reports only.

The IMD is a way of summarising the level of deprivation within an area, based on a set of factors that includes their levels of income, employment, education and local levels of crime. Episodes were linked to IMD using patient postcode (and laboratory postcode where patient postcode was unavailable) and the IMD decile score was identified by the lower super-output area the patient resided in.

The Office for Health Improvements and Disparities developed a method for assigning ethnic group based on hospital admissions data. As different ethnicities may be recorded in different treatment episodes, the method selected a single ethnic group from a patient’s HES records. Episodes were linked to an ethnic group using the patient’s NHS number.

The following report summarises trends and geographical distribution of carbapenemase mechanisms identified in Gram-negative bacteria isolated from human samples. Bacterial species, mechanism, sample type, age, sex, IMD and ethnic group of patients are also described. For the purposes of this report, quarters are calendar quarters; as such, January to March is referred to as ‘Q1’, April to June is ‘Q2’, July to September is ‘Q3’ and October to December is ‘Q4’.

Please note that scientific names are not italicised in this report to ensure our content is inclusive for all users and in compliance with web accessibility legislation and associated guidelines.

Microbiology services

For reference services, including species identification and confirmation of susceptibility testing results, laboratories should contact UKHSA’s Antimicrobial Resistance and Healthcare Associated Infections (AMRHAI) Reference Unit in Colindale, London.

Table 1 summarises the carbapenemase gene families that are targeted using the PCR applied to referred Enterobacterales, Pseudomonas spp. and Acinetobacter spp. that are suspected to harbour an acquired carbapenemase gene. UKHSA strongly recommends that all diagnostic laboratories seek at least the 4 carbapenemase families in bold in the table (the ‘big 4’) using either PCR or immunochromatographic methods.

Where an ‘exceptional’ carbapenemase and genus combination result (cells without a ¥ symbol in Table 1) has been identified, or where an unusual organism has been identified with an acquired carbapenemase (that is, any bacterial genera other than a member of the Enterobacterales, Pseudomonas spp. or Acinetobacter spp.), isolates should be sent to the AMRHAI Reference Unit for confirmation.

Table 1. Distribution among bacterial pathogens of carbapenemase genes covered by AMRHAI Reference Unit’s molecular assay (based on AMRHAI data) [note 1]

Carbapenemase family	Associated with common ‘host’ organism Enterobacterales	Associated common ‘host’ organism Pseudomonas spp.	Associated with common ‘host’ organism Acinetobacter spp.
KPC	¥	<10D	<10D
OXA-48-like	¥	<50E	0
NDM	¥	¥	¥
VIM	¥	¥	<10D
IMP	¥	¥	¥
IMI/NMC-A	¥B	0	0
GES	¥	¥	<10D
FRI	<10 D	0	0
SME	¥ C	0	0
DIM	0	<50E	0
GIM	<10D	<10D	0
SIM	0	<10D	0
SPM	0	<10D	0
OXA-23-like	<50E	0	¥
OXA-40-like	0	0	¥
OXA-51-likeA	0	0	¥
OXA-58-like	0	0	¥

Note 1. Table 1 uses the following symbols:

¥ = combinations of mechanism and genus are not considered exceptional.

A = intrinsic to A. baumannii and only expressed when associated with an insertion element.

B = almost exclusively reported in Enterobacter spp. with less than a handful of reports in other genera.

C = reported only in Serratia marcescens.

D = fewer than 10 in total ever confirmed by AMRHAI Reference Unit.

E = fewer than 50 in total ever confirmed by AMRHAI Reference Unit

Recent developments

Unusual acquired CPOs referred to the AMRHAI Reference Unit in Q4 2024 included 2 OXA-23-positive Proteus mirabilis, referred from the East Midlands (from bone) and the West Midlands (from a urine culture). One DIM metallo-carbapenemase positive Pseudomonas putida from a rectal swab was referred from the South East and one GES carbapenemase positive Pseudomonas aeruginosa from a rectal swab was referred from the South West. As OXA-23, DIM and GES genes are not detected using diagnostic assays that target the ‘big 4 or 5’ carbapenemase families (‘big 5’ includes IMP), laboratories are reminded to refer isolates that meet AMRHAI referral criteria (2) to the Reference Unit for screening for rarer carbapenemase genes.

The most common dual carbapenemase combination observed amongst Reference Unit referrals was NDM + OXA-48-like. However, in Q4 2024 the following combinations were also identified: one each of IMP + KPC (in Enterobacter cloacae complex), IMP + NDM (in Citrobacter freundii), KPC + NDM (in Klebsiella pneumoniae) and KPC + OXA-48-like (in Enterobacter cloacae complex). Isolates with these combinations are currently rare amongst AMRHAI submissions and should be referred for confirmation (free-of-charge for NHS laboratories) and inclusion in the AMRHAI strain collection.

Locally-confirmed unusual combinations of organism and mechanism should also be referred to the AMRHAI Reference Unit for confirmation. Follow up of these unusual combinations has identified some have been due to mixed cultures or reporting errors.

Specimen type

Between October 2020 and December 2024, there were 20,544 acquired CPO episodes reported. The majority were identified in screening samples, accounting for 71.7% of notifications, with 910 (4.4%) reported from sterile site specimens (Table 2).

Table 2. Number and percentage of acquired CPO episodes by specimen type (England): October 2020 to December 2024

Specimen type	All reports number	All reports percentage [note 3]	AMRHAI reports number	AMRHAI reports percentage [note 4]
Sterile site samples	910	4.4	292	10.1
Screening samples	14,729	71.7	1,370	47.6
Other samples [note 2]	4,905	23.9	1,217	42.3
All samples	20,544	100.0	2,879	100.0

Note 2. Samples that did not fall into either ‘sterile site’ or ‘screening’ samples, for example, urine and lower genital tract specimens.
Note 3. The percentages presented in this table are column percentages, with the breakdown of specimen types shown for all reports and AMRHAI reports separately.
Note 4. The AMRHAI Reference Unit actively encourages submission of sterile site isolates for carbapenemase confirmation; the distribution of specimen type will reflect this.

Quarterly trends

For Q1 to Q4 2024, the overall annual rate of CPO episodes in England was 13.0 per 100,000 population. The quarterly rate of CPO episodes has decreased from the highest rate (3.7 CPO episodes per 100,000 in Q3 2024) since mandatory reporting began in Q4 2020, with a rate of 3.3 episodes per 100,000 in Q4 2024 (Figure 1). This decrease was predominantly due to a 15.8% decrease in positive screening samples between Q3 2024 and Q4 2024 (n= 1,549 to 1,304). The decrease in the number of positive screening samples was localised to the North East, the North West and London (a decrease of 41.6%, 24.8%, and 13.4%, respectively) (see accompanying data tables, Data Appendix 1). However, the number of sterile site infections increased by 8.5% in Q4 2024 compared with Q3 2024 (n= 82 episodes in Q3 2024 to 89 in Q4 2024) (Figure 1), with the number of reported sterile site infections more than doubling from Q4 2020 to Q4 2024 (see accompanying data tables).

Changes to screening policies, outbreaks, and/or an improvement in national reporting of CPO episodes can have a substantial impact on overall CPO trends; it is therefore important to note that an increase in reported episodes may be due in part to changes in screening policies change and national reporting improvements over time. There appears to be seasonality in the number of positive reported screening samples, with peaks in Q3 over the last 3 years and subsequent drops in Q1. However caution should be taken when interpreting seasonal trends, especially for ‘other’ and sterile site specimens as there are only 16 quarters of notification data (including over the COVID-19 period), and local outbreaks may influence sampling and incidence.

Figure 1. Quarterly rate of acquired CPO episodes by specimen type and quarter (England): October 2020 to December 2024

Epidemiology of CPO episodes over the last year (Q1 2024 to Q4 2024)

The data summaries in the rest of this report consider all sample types grouped together and only for the past rolling year (January 2024 to December 2024), using both annual and quarterly rates.

Geographical distribution

The annual rate of acquired CPO episodes varied by region (Office for National Statistics [ONS] regions) (Figure 2a), with the highest overall rate between January 2024 and December 2024 reported in London (26.2 episodes per 100,000 population), followed by the North West region (22.7 episodes per 100,000 population). The lowest annual incidence across the last year was reported in the South West region (2.6 episodes per 100,000 population).

At the ICB level, NHS North West London ICB had the highest rate of reports (40.2 episodes per 100,000) followed by NHS Greater Manchester ICB (33.5 episodes per 100,000 population) and NHS Staffordshire and Stoke-on-Trent ICB (31.5 episodes per 100,000 population) (Figure 2b). The lowest annual incidence across the last year was reported in the NHS Gloucestershire ICB (0.8 episodes per 100,000 population). Regional and ICB variation can be due to differences in incidence, as well as variation in screening policies, outbreaks and reporting to national surveillance.

Figure 2a. UKHSA regional distribution of acquired CPO annual incidence rates per 100,000 population (England): January 2024 to December 2024 [note 5]

Contains OS data © Crown copyright and database right 2024

Figure 2b. Integrated Care Board (ICB) regional distribution of acquired CPO annual incidence rates per 100,000 population (England): January 2024 to December 2024 [note 5]

Contains OS data © Crown copyright and database right 2024

Note 5. The region geography is based on the patient’s residential postcode (if unknown, the laboratory location was used) and linked to the ONS data for regions (Figure 2a) and ONS data for ICBs (Figure 2b).

The number and quarterly rate of reported acquired CPO episodes for each ONS region by calendar quarter are shown in Table 3. The quarterly rate of reported CPO episodes in ONS regions decreased between Q3 2024 and Q4 2024 in most regions. The largest decrease in rates from Q3 2024 to Q4 2024 were seen in the North East (6.8 to 4.4 per 100,000 population) and the North West (6.9 to 5.3 per 100,000 population). In Yorkshire and the Humber, the South West and the East of England rates increased between Q3 2024 and Q4 2024 (1.9 to 2.5 per 100,000, 0.6 and 0.9 per 100,000, and 1.2 to 1.4 per 100,000 respectively).

Table 3. Number of acquired CPO episodes and quarterly rate per 100,000 population for all specimen types by ONS region (England): January 2024 to December 2024

ONS region	Q1 2024 number	Q1 2024 rate	Q2 2024 number	Q2 2024 rate	Q3 2024 number	Q3 2024 rate	Q4 2024 number	Q4 2024 rate
London	472	5.3	668	7.5	628	7.1	557	6.3
North West	365	4.9	419	5.6	521	6.9	398	5.3
West Midlands	203	3.4	272	4.5	352	5.9	303	5.0
North East	77	2.9	190	7.1	182	6.8	119	4.4
Yorkshire and The Humber	125	2.3	90	1.6	104	1.9	137	2.5
South East	109	1.2	116	1.3	153	1.7	152	1.7
East of England	73	1.1	76	1.1	79	1.2	92	1.4
East Midlands	64	1.3	84	1.7	60	1.2	50	1.2
South West	30	0.5	34	0.6	33	0.6	51	0.9

Geographical differences in carbapenemase family distribution

Between January 2024 and December 2024, the most common carbapenemase families reported across all regions were NDM (35.9%), OXA-48-like (34.4%), and KPC (19.6%), although the distribution of carbapenemase families identified varied regionally (Figure 3). The diversity of carbapenemases reported in regions may be impacted by individual outbreaks, especially in regions with small numbers of cases or in trends over time for less commonly identified mechanisms.

In London, which had the highest annual incidence rate, the most reported carbapenemase families were NDM (47.3%) and OXA-48-like (37.6%). In contrast, KPC (41.1%) was the dominant carbapenemase family in the North West. KPC was not as common in the other regions, accounting for fewer than a third of episodes in each region; in London, KPC accounted for only 3.8% of episodes.

IMP was most reported carbapenemase family in the North East (22.2%), Yorkshire and the Humber (14.3%), and South West (10.1%); other regions ranged between 2.8% and 6.4%.

The distribution of carbapenemase families varied in each quarter in some ONS regions (see accompanying data tables, Data Table Appendix 2). For example, the most reported carbapenemase family in Yorkshire and the Humber and the South West was OXA-48-like in Q1 2024 (30.4% (n=38) and 43.3% (n= 13), respectively), but switched to NDM in Q4 2024, (35.0% (n=48) and 39.2% (n= 20), respectively). Between Q1 2024 and Q4 2024 in Yorkshire and the Humber, the number of IMP reports more than doubled from 13 to 28 (10.4% to 20.4%). A similar increase in IMP occurred in the West Midlands in the past 4 quarters (1.0% (n= 2) in Q1 2024 to 6.9% (n= 21) in Q4 2024). There was an increase in the East Midlands in reports of KPC, from 1.6% (n=1) in Q1 2024 to 20.0% (n=10) in Q4 2024 (see accompanying data tables, Data Table Appendix 2). NDM remains the most common (66.0% (n=36) in Q4 2024) carbapenemase family in the region.

Figure 3. Geographical distribution of acquired CPO episodes by carbapenemase family (England): January 2024 to December 2024 [note 6]

Note 6. Other carbapenemase families included DIM, GES, IMI, and OXA-23 (in Enterobacterales).

Distribution of species and carbapenemase family

In 2024, the most frequently isolated Gram-negative bacterial species with an acquired carbapenemase were Escherichia coli (34.1%), Klebsiella pneumoniae (32.2%) and Enterobacter spp. (18.4%) (Table 4).

The carbapenemase family most frequently identified in E. coli and K. pneumoniae isolates was OXA-48-like (47.1% and 33.3%, respectively), followed by NDM (40.2% and 30.4%, respectively) and KPC (8.8% and 29.9%, respectively). In Enterobacter spp. isolates, the most common carbapenemase family was NDM (36.9%), followed by KPC (21.7%) and OXA-48-like (19.5%).

Aside from the ‘big 5’ carbapenemase families (KPC, OXA-48-like, NDM, VIM and IMP), the AMRHAI Reference Unit also screens for rarer carbapenemase families, and it is recommended that all isolates suspected to produce an acquired carbapenemase but that test negative for the ‘big 4 or 5’ carbapenemase families (depending on the testing capabilities of the local laboratory) are referred to the AMRHAI Reference Unit for further testing. Between October 2020 and December 2024, DIM, GES, GIM, IMI, OXA-23 (in Enterobacterales) and SME carbapenemases were identified in small numbers of isolates and represented less than 2.9% of all reports.

Table 4. Acquired CPO episodes by species and carbapenemase family (England): January 2024 to December 2024

Species	IMP no. (%)	KPC no. (%)	NDM no. (%)	OXA-48-like no. (%)	VIM no. (%)	Other [note 6] no. (%)	Total no.	% of Total
Escherichia coli	79 (3.1)	223 (8.8)	1,018 (40.2)	1,193 (47.1)	18 (0.7)	1 (0.0)	2,532	34.1
Klebsiella pneumoniae	102 (4.3)	716 (29.9)	729 (30.4)	797 (33.3)	50 (2.1)	1 (0.0)	2,395	32.2
Enterobacter spp.	250 (18.3)	296 (21.7)	504 (36.9)	267 (19.5)	39 (2.9)	11 (0.8)	1,367	18.4
Citrobacter spp.	49 (14.5)	61 (18.0)	94 (27.8)	115 (34.0)	19 (5.6)	0 (0.0)	338	4.5
Klebsiella oxytoca	10 (4.5)	109 (49.5)	21 (9.5)	70 (31.8)	10 (4.5)	0 (0.0)	220	3.0
Other Enterobacterales [note 8]	5 (3.0)	19 (11.4)	112 (67.1)	30 (18.0)	1 (0.6)	0 (0.0)	167	2.2
Pseudomonas aeruginosa [note 7]	13 (8.7)	2 (1.3)	75 (50.0)	6 (4.0)	45 (30.0)	9 (6.0)	150	2.0
Other Klebsiella spp.	5 (4.8)	24 (22.9)	21 (20.0)	51 (48.6)	4 (3.8)	0 (0.0)	105	1.4
Acinetobacter spp. [note 7]	2 (2.5)	0 (0.0)	74 (91.4)	3 (3.7)	2 (2.5)	0 (0.0)	81	1.1
Serratia spp.	2 (7.1)	5 (17.9)	11 (39.3)	10 (35.7)	0 (0.0)	0 (0.0)	28	0.4
Other Pseudomonas spp. [note 7]	0 (0.0)	0 (0.0)	1 (6.3)	0 (0.0)	14 (87.5)	1 (6.3)	16	0.2
Other Escherichia spp.	1 (6.7)	3 (20.0)	5 (33.3)	4 (26.7)	2 (13.3)	0 (0.0)	15	0.2
Morganella spp.	0 (0.0)	1 (8.3)	2 (16.7)	9 (75.0)	0 (0.0)	0 (0.0)	12	0.2
Other Gram-negative bacteria [note 9]	0 (0.0)	0 (0.0)	3 (42.9)	2 (28.6)	2 (28.6)	0 (0.0)	7	0.1
Total	518 (7.0)	1,459 (19.6)	2,670 (35.9)	2,557 (34.4)	206 (2.8)	23 (0.3)	7,433	100.0

Note 6. ‘Other’ carbapenemase families included DIM, GES, IMI, and OXA-23 (in Enterobacterales). Isolates identified as positive for ‘Other’ carbapenemase families should be referred to the AMRHAI Reference Unit for confirmation.

Note 7. KPC and OXA-48-like in Pseudomonas spp. and Acinetobacter spp. are extremely rare, and positive results should be interpreted with caution. Laboratories identifying these unusual combinations should refer such isolates to the AMRHAI Reference Unit.

Note 8. Includes coliform, Cronobacter spp., Hafnia spp., Kluyvera spp., Leclercia adecarboxylata, Lelliottia amnigena, Mixta calida, Pantoea spp., Phytobacter ursingii, Pluralibacter gergoviae, Proteus spp., Providencia spp., Raoultella spp., and Shigella spp.

Note 9. The isolates reported here have not all been confirmed by the AMRHAI Reference Unit and laboratories identifying these unusual combinations should refer such isolates to AMRHAI

Distribution of demographic risk factors

In 2024, the annual rate of reported acquired CPO episodes was highest among the oldest and youngest members of the population. A similar age pattern was noted for both sexes, although overall the annual rate was higher in males compared to females (overall rates of 14.5 and 11.5 episodes per 100,000 population, respectively; Figure 4). This aligns with the age group and sex distribution noted in previously published reports on Gram-negative bacteraemia such as E. coli, Klebsiella spp., P. aeruginosa and Enterobacter spp.

Figure 4 shows the reported acquired CPO annual incidence rates by age group in 2024, with the highest annual rate reported in those 85 years and over (72.4 per 100,000 population) followed by those aged 75 to 84 years (45.1 per 100,000 population). For infants less than one year old, the CPO annual incidence rate was 9.4 per 100,000 population.

Figure 4. Annual rate of acquired CPO episodes per 100,000 population by age and sex [note 10] (England): January 2024 to December 2024

Note 10. Information about patient sex is recorded in 99.5% of cases.

Figure 5 shows the reported acquired CPO annual incidence rates by ethnic group and sex in 2024, with the highest annual rate reported in those of Asian or Asian British ethnicity (21.4 per 100,000 population), followed by those of Black, Black British, Caribbean or African ethnicity (16.7 per 100,000 population). A similar pattern was noted for both sexes, although overall the annual rate was higher in males compared to females (Figure 5).

Figure 5. Annual rate of acquired CPO episodes per 100,000 population by ethnic group [note 11] and sex [note 10] (England): January 2024 to December 2024

Note 10. Information about patient sex is recorded in 99.5% of cases.

Note 11. Information about patient ethnicity is recorded in 89.8% of cases.

The most common carbapenemase families identified in individuals of Asian or Asian British ethnicity were NDM (55.3%, n=641) and OXA-48-like (34.8%, n=403) (Figure 6). KPC was not as commonly identified in patients of Asian or Asian British ethnicity (5.1%, n=59) as it was in those of White ethnicity, where KPC accounted for 25.9% of episodes (n=1,234).

Figure 6. Distribution of acquired carbapenemase families by ethnic group [note 11] and (England): January 2024 to December 2024

Note 6. ‘Other’ carbapenemase families included DIM, GES, IMI, and OXA-23 (in Enterobacterales). Isolates identified as positive for ‘Other’ carbapenemase families should be referred to the AMRHAI Reference Unit for confirmation.

Note 11. Information about patient ethnicity is only recorded in 89.8% of cases.

Figure 7 shows the acquired CPO annual incidence rates by IMD decile and sex in 2024. The highest annual rate was reported in those in the most deprived decile (19.8 per 100,000 population). The annual rate generally declines as the IMD decile increases, with the lowest annual rate reported in the ninth IMD decile (7.3 per 100,000 population). A similar pattern was noted for both sexes, although overall the annual rate was higher in males compared to females (Figure 7).

Figure 7. Annual rate of acquired CPO episodes per 100,000 population by index of multiple deprivation decile and sex [note 10] (England): January 2024 to December 2024

Note 10. Information about patient sex is only recorded in 99.5% of cases.

Figure 8 shows the acquired CPO incidence annual rates by IMD decile and carbapenemase family in 2024. The 3 carbapenemase families with the highest annual rates across all IMD deciles are OXA-48-like, NDM, and KPC, where the annual rate generally declines with increasing IMD decile (least deprived) (Figure 8).

Figure 8. Annual rate of acquired CPO episodes per 100,000 population by index of multiple deprivation decile and resistance mechanism (England): January 2024 to December 2024

Note 6. ‘Other’ carbapenemase families included DIM, GES, IMI, and OXA-23 (in Enterobacterales). Isolates identified as positive for ‘Other’ carbapenemase families should be referred to the AMRHAI Reference Unit for confirmation.

Quarterly mandatory laboratory return reporting (January 2024 to December 2024)

Reporting of quarterly totals of rectal swabs and faecal specimens taken for CPO screening was added to the mandatory quarterly laboratory returns (QMLR) section of the HCAI DCS in October 2019, and reporting became mandatory in October 2020. In Q4 2024, there were 186,618 screens reported by 101 NHS trusts, representing an overall trust reporting rate of 74.8% (Table 5). As of the writing of this report, 14 (11.6%) trusts had not reported any screens and an additional 3 (2.5%) trusts reported zero screens between Q1 2024 and Q4 2024. The lower report rate for Q4 2024 may be due to late reports as the report rate for Q3 2024 has changed since the previous report (3).

The full list of reporting, including those that did not submit a return, is available in the data tables by individual NHS Acute Trust (Appendix table 3).

Table 5. Quarterly mandatory laboratory returns (QMLR) for the total number of rectal swabs and faecal screening specimens taken for CPO screening by acute Trust type [note 12] (England): January 2024 to December 2024

Trust type [note 12]	Q1 2024 reported screens (%)	Q1 2024 total number screens	Q2 2024 reported screens (%)	Q2 2024 total number screens	Q3 2024 reported screens (%)	Q3 2024 total number screens	Q4 2024 reported screens (%)	Q4 2024 total number screens
Small (n=19)	15 (78.9)	5,961	14 (73.7)	7,268	14 (73.7)	8,240	10 (52.6)	5,494
Medium (n=20)	20 (100.0)	7,184	20 (100.0)	10,127	18 (90.0)	11,957	18 (90.0)	11,360
Large (n=23)	19 (82.6)	20,274	20 (87.0)	20,720	20 (87.0)	21,940	16 (69.6)	21,408
Multi-service (n=7)	7 (100.0)	8,763	7 (100.0)	10,831	6 (85.7)	10,976	6 (85.7)	12,112
Specialist (n=16)	12 (75.0)	6,457	14 (87.5)	8,417	14 (87.5)	13,881	12 (75.0)	11,993
Teaching (n=50)	43 (86.0)	119,473	43 (86.0)	127,185	40 (80.0)	118,358	39 (78.0)	124,251
Total (n=135)	116 (85.9)	168,112	118 (87.4)	184,548	112 (83.0)	185,352	101 (74.8)	186,618

Note 12. Trust type obtained through NHS Digital Estate Return Information Collection (ERIC).

References

1. Department of Health and Social Care. The Health Protection (Notification) (Amendment) (No. 2) Regulations 2020 No. 674 2020
2. UK Health Security Agency. Bacteriology reference department user manual 2023
3. UK Health Security Agency. Carbapenemase-producing Gram-negative organisms in England since October 2020: quarterly update, Q3 2024 2024

Acknowledgements

These reports would not be possible without the weekly contributions from microbiology colleagues in laboratories across England. The support from colleagues within the UK Health Security Agency, and the AMRHAI Reference Unit in particular, is valued in the preparation of the report. Feedback and specific queries about this report are welcome via hcai.amrdepartment@ukhsa.gov.uk