Research and analysis

HPR volume 12 issue 10: news (16 March)

Updated 21 December 2018

Mandatory HCAI reports quarterly trends: October to December 2017

PHE’s latest quarterly epidemiological commentary on trends in reports of MRSA, MSSA and Gram-negative bacteraemia, and C. difficile infections (CDI), mandatorily reported by NHS acute Trusts in England up to October to December 2017, has been published on GOV.UK [1].

The report includes tabular and graphical presentation of data for the October to December 2017 quarter (updating the previous report published in December 2017). The main facts are listed below.

MRSA bacteraemia

There was a steep decline of 85% in the incidence rate (per 100,000 population) of all reported cases between April to June 2007 and January to March 2014 (from 10.2 to 1.5). This is followed by a 16% decrease in incidence rates from 1.5 to 1.3 cases per 100,000 population between January to March 2014 and October to December 2017.

The PIR process for all MRSA bacteraemia cases began in April 2013. Between April 2013 and March 2014, the incidence rate of trust-assigned cases remained stable at 1.2 cases per 100,000 bed days while the incidence rate of CCG-assigned cases decreased by 22% from 1.0 to 0.7 cases per 100,000 population.

Following the introduction of third-party assignment category in April 2014, counts and incidence rates of CCG-assigned cases decreased slightly from 91 to 75 cases and from 0.7 to 0.5 (per 100,000 population) respectively between April to June 2014 and October to December 2017. This decrease is mostly due to the introduction of the third-party assignment category, as several cases which would be classified as CCG-assigned are now classified as third-party assigned.

Over the same period (April to June 2014 to October to December 2017), counts and incidence rate (per 100,000 bed days) of trust-assigned cases have remained relatively stable at an incidence rate of 0.8 to 73-71 cases. Similarly within the same period, the counts and incidence rate (per 100,000 population) of third-party assigned cases increased from 17 to 34 cases and 0.1 to 0.2 respectively.

MSSA bacteraemia

Since the mandatory reporting of MSSA bacteraemia began in January 2011 there has been a general trend of increasing counts and incidence rates. All reported cases of MSSA bacteraemia increased by 34% from 2,199 to 2,941 between January to March 2011 and October to December 2017. This was accompanied by a 26% increase in incidence rate (per 100,000 population) from 16.8 to 21.2.

These increases are driven by community-onset cases. Over the same period (January 2011 to December 2017), counts and incidence rates of community-onset cases increased by 46% and 37% respectively (from 1,464 and 2,134 cases, and 11.2 and 15.4 cases per 100,000 population), while both counts and incidence rates of hospital-onset case increased by only 10% (from 735 and 807 cases, and 8.4 and 9.2 cases per 100,000 bed days).

When comparing the most recent quarter with the same period last year (October to December 2016 and October to December 2017), the incidence rate of hospital-onset MSSA bacteraemia increased by 5% from 8.8 to 9.2 cases per 100,000 bed days compared to the 1% increase in incidence rates of community-onset cases from 15.2 to 15.4 cases per 100,000 population over the same period.

Escherichia coli bacteraemia

Seasonal peaks are seen in all reported cases of E. coli bacteraemia between July and September each year. Beginning from April to June 2013, each quarter of each year has been higher than the same quarter in the preceding year, implying an increase over the overall time period. The seasonal peaks in all reported cases are due to the seasonality of community-onset cases.

Between July to September 2011 and October to December 2017, all reported cases of E. coli bacteraemia increased by 24% from 8,275 to 10,255 cases. Over the same period, incidence rates also increased by 19% from 61.8 to 73.8 cases per 100,000 population. Similarly over the same period, community-onset cases increased by 33% from 6,279 to 8,345 cases. Incidence rate (per 100,000 population) also increased by 28% from 46.9 to 60.1.

Unlike community-onset cases, hospital-onset cases decreased slightly from 1,996 to 1,910 cases corresponding to an 4% decrease in the associated incidence rate from 23.7 to 22.8 per 100,000 bed days between July to September 2011 and October to December 2017.

A similar trend is observed when comparing the most recent quarter and the same quarter from the previous year (October to December 2016 to October to December 2017). There was a 1% increase in both counts and incidence rate of all reported cases from 10,140 to 10,255 cases and from 73.0 to 73.8 cases per 100,000 population respectively. Also, both counts and incidence rate of community-onset cases increased by 2% from 8,214 to 8,345 cases, and from 59.1 to 60.1 cases per 100,000 population, respectively. Over the same period, both counts and incidence rate of hospital-onset cases decreased by 1% from 1,926 to 1,910 cases, and from 21.9 to 21.7 cases per 100,000 bed days, respectively.

Klebsiella spp. bacteraemia

Between the start of mandatory surveillance of Klebsiella spp. bacteraemia (April 2017) and October to December 2017, a total of 7,338 cases of Klebsiella spp. bacteraemia have been reported at an incidence rate of 17.7 cases per 100,000 population – 16.7, 18.7 and 17.7 cases per 100,000 population in 2017 to 2018 Q1, Q2 and Q3 respectively. During this time, 29% (n=2,142) were hospital-onset cases with an incidence rate of 7.5, 8.9 and 8.3 cases per 100,000 bed days in 2017 to 2018 Q1, Q2 and Q3 respectively. The remaining 71% (n=5,196) were community-onset cases, an incidence rate of 12.5 cases per 100,000 population – 12.0, 13.2 and 12.4 cases per 100,000 population in 2017 to 2018 Q1, Q2 and Q3 respectively.

Furthermore, over the same period, 64% (4,686/7,338) of all reported Klebsiella spp. bacteraemia were caused K. pneumoniae (the most frequently reported species) compared to 15% (1,071/7,338) caused by K. oxytoca (the next most frequently reported species).

Pseudomonas aeruginosa bacteraemia

Mandatory surveillance of P. aeruginosa bacteraemia began in April 2017. Since that time (April to June 2017 and October to December 2017), 3,312 cases of P. aeruginosa bacteraemia have been reported at an incidence rate of 8.0 cases per 100,000 population – 7.3, 8.4 and 8.2 cases per 100,000 population in 2017 to 2018 Q1, Q2 and Q3 respectively. During this time, 37% (n=1,217) were hospital-onset cases with incidence rates of 4.3, 4.9 and 4.9 cases per 100,000 bed days in 2017 to 2018 Q1, Q2 and Q3 respectively. The remaining 63% (n=2,095) were community-onset cases, an incidence rate of 5.0 cases per 100,000 population – 4.7, 5.4 and 5.1 cases per 100,000 population in 2017 to 2018 Q1, Q2 and Q3 respectively.

Clostridium difficile infection

Since the initiation of CDI surveillance in April 2007, there has been an overall decrease in counts and associated incidence rate of both all reported and hospital-onset cases of CDI. Seasonal peaks are present in January to March quarters prior to 2014/15 and the July to September quarters between 2014 to 2015 and 2016 to 2017. This is particularly apparent among hospital-onset cases.

The bulk of this decrease occurred between April to June 2007 and January to March 2012 with a 78% decrease in total (all reported) cases of CDI from 16,864 to 3,711 cases and an associated 79% reduction in incidence rate (per 100,000 population) from 131.6 to 27.9. Subsequently between January to March 2012 and October to December 2017, all reported case reduced by 13% from 3,711 to 3,221 cases and incidence rate reduced by 17% from 27.9 and 23.2.

There were similar but greater reductions among hospital-onset CDI cases – 85% reduction in cases from 10,436 to 1,613 cases and 84% reduction in incidence rate (per 100,000 bed days) from 112.5 to 18.2 between April to June 2007 and January to March 2012. This was followed by a further 29% decrease in counts (from 1,613 to 1,148 cases) and 28% decrease in incidence rate (from 18.2 to 13.1) between January to March 2012 and October to December 2017.

This shows that there has been a greater decline among hospital-onset CDI cases compared to all reported CDI cases during the surveillance period.

When the most recent quarter is compared with the same quarter last year (October to December 2016 and October to December 2017) both counts and incidence rate (per 100,000 bed days) of all reported CDI increased by 2% from 3,154 to 3,221 cases and 22.7 to 23.2 respectively, while both counts and incidence rate (per 100,000 bed days) of hospital-onset CDI cases both decreased slightly by 3% from 1,180 to 1,148 cases and 13.4 to 13.1 respectively.

Reference

1. PHE (8 March 2018). Quarterly epidemiological commentary: mandatory MRSA, MSSA, Gram-negative bacteraemia, and C. difficile infection data (up to October to December 2017).

Yellow fever cases in travellers ex-Brazil

NaTHNaC has advised health professionals to consider yellow fever (YF) when assessing unvaccinated individuals returning from YF-risk areas, Brazil in particular, after the UK became the fifth European country to report a case in a traveller returing from Brazil this year [1]. Previously, YF cases ex-Brazil had been diagnosed in the Netherlands, France, Switzerland and Romania.

As well as considering YF in the differential diagnoses for illnesses in unvaccinated individuals returning from YF-risk areas, NaTHNaC recommends that such cases should be discussed with the local microbiology, virology or infectious disease consultant.

Health professionals can contact the Imported Fever Service for advice about unwell returned travellers.

A map showing the current areas where yellow fever vaccine is recommended in Brazil is available from the European Centre for Disease prevention and Control (ECDC).

Reference

1. NaTHNaC (15 March). Yellow fever cases in travellers: update.

Infection reports in this issue: polymicrobial bacteraemia annual report

The overall rate of polymicrobial bacteraemia or fungaemia in England, Wales and Northern Ireland increased 82.0% between 2013 and 2017, from 14.5 to 26.3 per 100,000 population, according to the annual update on voluntarily-reported cases, published in this issue of HPR [1].

In 2017, 10.6% (15,868/167,681) of bloodstream infection episodes were identified as polymicrobial, an increase from 2013 (8.5%; 8,514/109,436). The top 3 organisms identified in polymicrobial infection in 2017 were E. coli (14.9%), coagulase negative staphylococci (13.1%) and coliforms not further speciated (6.4%). Rates of polymicrobial bloodstream infection were highest in over 75s (128.7/100,000) and those aged less than one year (68.5/100,000).

Reference

1. Polymicrobial bacteraemia and fungaemia (EWNI): 2017, HPR 12(10): infection report.