Research and analysis

HPR volume 10 issue 44: news (16 December)

Updated 16 December 2016

1. Surgical site infection surveillance in NHS hospitals: annual report in summary

PHE has published the latest results from its surveillance of surgical site infections (SSI) programme, summarising data collected by 218 NHS hospitals and nine independent NHS Treatment centres in England between April 2011 and March 2016 [1]. The report presents the cumulative incidence of SSI for 17 categories of surgical procedures based on infections detected during the patient’s post-operative stay (“inpatient SSIs”) combined with infections detected on re-admission after initial hospital discharge (“readmission SSIs”).

NHS Trusts in England performing orthopaedic surgery in one of the four mandatory surveillance categories (hip prosthesis, knee prosthesis, reduction of long bone fracture and repair of neck of femur) are required to undertake SSI surveillance in at least one of these surgical categories in one hospital for a minimum of one quarter per financial year. NHS Trusts also have the option of participating in any of the additional 13 surgical categories included in the national surveillance scheme covering gastro-intestinal, cardiothoracic, neurosurgery, gynaecology, vascular and other general surgery procedures.

Surveillance of SSIs is undertaken by hospitals in England using standard definitions for infections that affect the superficial incisional site, the deeper layers or those involving the joint or organ-space [2]. Patients are systematically, prospectively followed up to identify infections occurring within 30 days of surgery, or within one year if a prosthetic implant is used.

The new report describes: frequency of hospital participation in the surveillance in 2015/16; data quality indicators; trends in the SSI incidence; risk factors for SSI; and microbial aetiology.

A supplement providing data on orthopaedic SSI incidence by NHS Trust (which will also be available in due course from PHE’s Fingertips website and NHS Choices) is also available from the PHE website [3].

1.1 Key findings

Key findings are:

• in 2015/16, data on 136,872 procedures and 1,632 surgical site infections (SSIs) detected during inpatient stay or on readmission following the initial operation were collected by 198 NHS hospitals and seven independent sector NHS treatment centres across 17 surgical categories
• mandatory orthopaedic data comprised 103,838 procedures and 670 inpatient/readmission SSIs in 2015/16 collected by 138 NHS Trusts and an additional seven NHS treatment centres
• for the mandatory orthopaedic surveillance, nine NHS trusts were identified as high outliers in 2015/16. Eight NHS trusts and one NHS treatment centre were identified as low outliers. All 18 providers have been contacted and asked to investigate possible reasons
• the cumulative SSI incidence (data from April 2011 to March 2016) varied by surgical category depending on the inherent wound contamination, ranging from 9.8% for large bowel surgery to <1% for hip and knee prosthesis
• a significant decrease in the SSI incidence occurred for repair of neck of femur from 1.7% in 2008/9 to 1.0% in 2015/16
• the SSI incidence remained low for hip and knee prosthesis (<1%) with decreasing trends observed for hip prosthesis in the last three successive years
• trends in SSIs for the other categories (from 2008/9 to 2015/16) identified a significant increase for spinal surgery from 1.4% in 2008/9 to 1.8% in 2015/16
• a significantly decreasing trend occurred in bile duct/liver/pancreatic surgery from 9.6% in 2008/9 to 5.2% in 2015/16. In gastric and large bowel surgery decreasing trends were identified in recent years (3.1% and 8.5% respectively in 2015/16)
• Enterobacteriaceae continued to increase, accounting for 28% of SSIs in 2015/16, the highest to date. Staphylococcus aureus accounted for 13% of inpatient SSIs in 2015/16 whilst the methicillin-resistant form (MRSA) accounted for 4%, both decreasing since 2006/7. Small, steady decreases in methicillin-susceptible S. aureus (MSSA) were observed since 2013/14, reaching 9% of SSIs in 2015/16
• S. aureus predominated in orthopaedic and spinal surgery accounting for ≥35% of SSI cases. Coagulase-negative staphylococci and Enterobacteriaceae predominated in coronary artery bypass graft and large bowel surgery SSIs respectively
• in primary total hip prosthesis, the proportion of SSIs due to S. aureus was highest in the uncemented (46%) compared to the cemented (37%) and hybrid fixation (31%) groups
• data completion for age, patient sex and duration of operation was high in 2015/16 (≥95% of submitted records) in the majority of surgical categories. Data completion for ASA score (standardised pre-operative health classification) and BMI continued to vary between surgical categories. BMI data completion of ≥50% was achieved in nine surgical categories in 2015/16 compared to six in 2014/15.

1.2 References

1. PHE (12 December 2016). Surveillance of surgical site infections in NHS Hospitals in England 2015/16. See: Surgical site infections surveillance: NHS hospitals in England.

2. PHE (June 2013). Protocol for the surveillance of surgical site infection (version 6).

3. PHE (12 December 2016). Surgical site infections surveillance: NHS Trust tables 2015/2016. See: Surgical site infections surveillance: NHS hospitals in England.

2. Mandatory HCAI reports quarterly trends: July to September 2016

PHE’s latest quarterly epidemiological commentary on trends in reports of Staphylococcus aureus (MRSA and MSSA) and Escherichia coli bacteraemia, and of Clostridium difficile infections, mandatorily reported by NHS acute Trusts in England up to end-September 2016, has been published on the GOV.UK website [1].

The report includes tabular and graphical presentation of data for the July-September quarter and updates the previous report published in September 2016. Some key facts are listed below.

2.1 MRSA bacteraemia

There has been a general decreasing trend of reported MRSA bacteraemia since enhanced surveillance began in April 2007. Between April-June 2007 and July-September 2016, counts and rates of all reported cases decreased by 86% (1,306 to 182 cases) and 87% (10.2 to 1.3 cases per 100,000 population) respectively. In the most recent quarters between July-September 2015 and July-September 2016 the rate of all reported MRSA bacteraemia reduced from 1.5 to 1.3 cases per 100,000 population (from 202 to 182 cases). Over the same period (July-September 2015 and July-September 2016) rates of trust-assigned MRSA bacteraemia increased from 0.8 to 0.9 cases per 100,000 bed-days. Rates of CCG-assigned cases levelled at 0.5 cases per 100,000 population and rates of third-party assigned cases levelled at 0.5 before reducing to 0.3 cases per 100,000 population in July-September 2016 (table 1b). The rate of all reported MRSA bacteraemia was higher among males (2.0 cases per 100,000 population) compared to females (0.9 cases per 100,000 population) over this time period (July-September 2015 to July-September 2016).

2.2 MSSA bacteraemia

Between January-March 2011 and July-September 2016 there has been an overall increase in the counts and rates of all reported MSSA bacteraemia by 27% (2,199 to 2,803 reports) and 20% (from 16.9 to 20.3 cases per 100,000 population) respectively. However, over the same period, the number of trust-apportioned cases has remained fairly stable (from 735 to 728 cases), while the associated trust-apportioned rate has increased by 3% from 8.4 to 8.6 cases per 100,000 bed-days. These increases were also observed when comparing the most recent quarters. Between July-September 2016 and the same quarter in the previous financial year (July-September 2015), there was a 7% increase in both counts and rates of all reported MSSA bacteraemia (2,673-2,803 cases; 19.0-20.3 cases per 100,000 population respectively). Similarly a 4% increase in both counts and rates of trust-apportioned cases (701-728 cases; 8.3-8.6 cases per 100,000 bed-days respectively). Over the same period (July-September 2015 to July-September 2016), the rate of all MSSA bacteraemia reported in England was higher among males (25.5 cases per 100,000 population) compared to females (14.1 cases per 100,000 population).

2.3 E. coli bacteraemia

The counts and rates of all reported E. coli bacteraemia has increased steadily since the inception of mandatory surveillance of E. coli bacteraemia in July 2011 (figure 5). There has been an increase of 31% (8,275 to 10,864 cases) and 28% (61.7 to 78.8 cases per 100,000 population) in the counts and rates of all reported E. coli bacteraemia between July-September 2011 and July-September 2016, with seasonal peaks generally reported between July and September each year. This overall increase has also been observed in the most recent quarters. Between July-September 2015 and July-September 2016, there was an 8% increase in both counts (10,087 to 10,864 cases) and rates (73.1 to 78.8 cases per 100,000 population) of all reported cases. Over the same period (July-September 2015 to July-September 2016), the rate of all E. coli bacteraemia reported in England was higher among females (74.0 cases per 100,000 population) compared to males (69.6 cases per 100,000 population).

2.4 C. difficile infection (CDI)

There has been an overall decrease in the counts (78%; 16,864-3,628 cases) and rates (80%; 131.5-26.3 cases per 100,000 population) of all reported C. difficile infections (CDI) between April-June 2007 and July-September 2016 with seasonal peaks between July-September of each year. This decrease was also observed in the counts (88%; 10,436-1,253 cases) and rates (87%; 112.5-14.8 cases per 100,000 bed-days) of trust-apportioned cases over the same period. More recently, when comparing July-September 2015 and July-September 2016, the counts and rates of all reported CDI decreased by 10% (4,011 to 3,628 cases) and 9% (29.1 to 26.3 cases per 100,000 population) respectively. Similarly, the counts and rates of trust-apportioned CDI cases both decreased by 8% (1,356 to 1,253 cases and 16.0 to 14.8 cases per 100,000 bed-days respectively) over the same time period. Between July 2015 and September 2016, the rate of all CDI reported in England was higher among females (28.7 cases per 100,000 population) compared to males (20.8 cases per 100,000 population).

2.5 Reference

1. PHE (8 December 2016). Quarterly Epidemiological Commentary: Mandatory MRSA, MSSA and E. coli bacteraemia, and C. difficile infection data (up to July-September 2016).

3. Annual report for HPV vaccine coverage in 2015/16

A new PHE report on the human papillomavirus (HPV) vaccination programme for adolescent females in England has provided vaccine coverage data for the school year 2015/16 [1].

In March 2014, the JCVI advised changing the routine programme from a three- to two-dose schedule and this was implemented in September 2014. The new report presents vaccine coverage data for the completed two-dose HPV vaccination course for the first time: 85.1% of Year 9 females completed the two-dose course, compared to 86.7% completing a three-dose course in 2013/14.

Coverage for the first (priming) dose was 87.0% in Year 8 females in 2015/16, 2.4% lower than priming dose coverage in 2014/15.

It is noted that, during the 2015/16 academic year, the commitment to deliver on the childhood flu vaccine programme (extended to school years 1 and 2), school leaver booster programme (diphtheria/tetanus/polio vaccine), and the MenACWY routine and catch-up programme may have impacted on the capacity of school immunisation providers to deliver the HPV vaccination programme in some areas.

3.1 Reference

1. PHE (December 2016).HPV vaccination coverage report: 1 September 2015 to 31 August 2016)

4. Infection and vaccine coverage reports in this issue of HPR

The following reports are published in this issue of HPR. The links below are to the relevant webpage collections or publications.

4.1 Infection reports

• Laboratory confirmed pertussis (England, Q3/2016)
• Laboratory confirmed invasive meningococcal disease (England, Q3/2016)
• Uncommon pathogens involved in bacteraemia (EWNI, 2015)
• General outbreaks of foodborne illness in humans (England and Wales, weeks 44 to 47/2016)

4.2 Vaccine coverage reports

• COVER report: Q3/2016
• Preliminary vaccine coverage for the school based meningococcal ACWY (MenACWY) adolescent vaccination programme in England, 1 September 2015 to 31 August 2016.