Research and analysis

HPR volume 8 issue 32: news and travel health

Updated 23 December 2014

1. S. aureus bacteraemia (voluntary reporting) annual report

Recent trends in Staphylococcus aureus (S. aureus) bacteraemia incidence in England, Wales and Northern Ireland, and trends in antibiotic resistance, are described in the latest annual report on voluntarily reported laboratory data for 2013, published in the infection reports section of this issue of HPR [1].

In 2013, there were 9,533 voluntary reports of S. aureus bacteraemia, comprising 8,521 from England, 649 from Wales and 358 from Northern Ireland. This represents a 4.6% increase from the 9,117 episodes reported in 2012.

This increase is predominantly due to the 5.6% increase observed in meticillin susceptible S. aureus (MSSA), from 6,977 in 2012 to 7,368 in 2013, which is the first annual increase observed in MSSA since 2007.

In comparison, 1,001 meticillin resistant S. aureus (MRSA) bacteraemia episodes were reported in 2013, which represents a small decrease (2.1%) from the 1,022 reports in 2012. The number of MRSA bacteraemias has declined year-on-year since 2004, however the rate of decline has slowed considerably since 2011.

These trends are supported by data from the mandatory reporting system.

In both males and females, the highest rates of MRSA bacteraemia (9.7 and 3.8 per 100,000 population, respectively) were seen in those aged 65 years and over. Rates of MRSA bacteraemia were significantly higher in males than females only in the 45 to 64 years and the over 64 years age groups (p<0.001).

MSSA bacteraemia rates were significantly higher among males than females in all age groups, with the highest rate being in males over 65 (48.4 per 100,000 population), as is the case with MRSA. However, there was also a high rate of MSSA bacteraemia in the under-1-year of age group (41.3 per 100,000 population); the highest MSSA rate among females was in this age group (31.6 per 100,000 population).

The majority of MRSA tested in 2013 were resistant to ciprofloxacin (81.7%) and erythromycin (63.6%), continuing the pattern of the past 5 years, and indeed since the mid-1990s. While the prevalence of resistance, among MSSA-causing bacteraemias, to commonly used antimicrobials for S. aureus infections has remained low over the last 5 years, there have been significant increases in fusidic acid and rifampicin resistance. However, the majority of MSSA remained susceptible to a broad range of antibiotics in 2013, including ciprofloxacin and erythromycin.

1.1 Reference

1. “Voluntary reporting of Staphylococcus aureus bacteraemia in England, Wales and Northern Ireland, 2013”, HPR 8(32): bacteraemia, 15 August 2014.

2. International outbreak of Salmonella Enteritidis affecting England, France and Austria

Public Health England (PHE) is investigating an outbreak of Salmonella Enteritidis PT14b in England that is possibly linked to outbreaks in France and Austria. Numbers of cases increased in June and July and this increase has been characterised by a series of local and regional outbreaks, primarily linked to restaurants and take aways serving Chinese food or similar cuisine [1]. Cases are currently defined as a resident of England infected with S. Enteritidis PT14b with the multi locus variable number tandem repeat analysis (MLVA) profile 2-12-9 -7-4-3-2-8-9 or 2-11-9-7-4-3-2-8-9 (the outbreak strain).

Since 1 June 2014, localised outbreaks have occurred in Hampshire, London and Cheshire and Merseyside in addition to a largely hospital based outbreak in Birmingham. All cases linked to these outbreaks conform to the national case definition. Further cases fit the case definition but are not linked to known outbreaks. MLVA on further isolates is pending and investigations to establish links between cases are underway. Over 200 people have been affected to date.

Whole genome sequencing shows some heterogeneity within the outbreak strain but indicates that all isolates are closely related irrespective of geographical location in England. All isolates examined so far are fully sensitive to antimicrobials.

S. Enteritidis PT14b has been isolated from food and environmental samples taken in Birmingham, Hampshire and Cheshire and Merseyside. The MLVA profile of the food and environmental isolates originating from Cheshire and Merseyside is the outbreak strain.

Although no similar increase in cases or outbreaks of S. Enteritidis PT14b has been seen in Scotland or Wales, concurrent breaks of S. Enteritidis of the same or similar strains are under investigation in France and Austria.

French authorities are investigating 6 outbreaks of S. Enteritidis affecting 49 people to date. Isolates from cases and food samples largely conform to the outbreak strain. However, the use of phage typing is not uniform across Europe and is not used in France. Further work is being conducted by GBRU to confirm whether the French cases are PT14b. The outbreak under investigation in Austria conforms to the outbreak strain.

The current assessment suggests that a common source is responsible for these outbreaks taking account of the evidence that:

• there are concurrent outbreaks of the same or very similar strains of S. Enteritidis with a wide geographical distribution within the UK and in 2 EU member states
• background isolates of S. Enteritidis PT14b, acquired both abroad and within England, are very different to the outbreak strain indicating a different source of infection.

A PHE outbreak control team has been formed and further investigations of the England cases are underway.

3. Updated guidance on gonorrhoea testing

PHE has published revised guidance – for commissioners of health services and service providers, and for laboratories – on good practice in gonorrhoea testing [1]. The new guidance takes account of the increasing availability of molecular “dual tests” for chlamydia and gonorrhoea (nucleic acid amplification tests, NAATs). This availability has led to the deployment of dual tests for samples collected for chlamydia screening by the National Chlamydia Screening Programme (NCSP), such that these samples are also being tested for gonorrhoea.

The NCSP – a programme of community-based opportunistic screening available to all sexually-active 15 to 24 year olds in England – is aimed at detection of the most commonly diagnosed bacterial sexually transmitted infection (chlamydia is 10 times more prevalent than gonorrhoea). Not only is gonorrhoea infection much rarer but incidence is more concentrated, both geographically and in particular risk groups, including men who have sex with men and black Caribbeans.

In low prevalence settings, the majority of initial positive gonorrhoea test results are likely to be false positives, suggesting that unselected screening would be of limited public health benefit. PHE has issued the new guidance to mitigate the potential harm associated with use of these tests in low prevalence settings.

A 2013 survey of local authority commissioners of sexual health services in England [2] found widespread use of dual tests for chlamydia and gonorrhoea on samples collected for chlamydia screening by the NCSP, suggesting that opportunistic screening for gonorrhoea has been occurring alongside chlamydia screening in many parts of the country where the prevalence of gonorrhoea is likely to be low. The new guidance highlights that there is no evidence to support widespread unselected screening for gonorrhoea in the UK.

Associated with the testing guidance are 2 supplementary documents: a gonorrhoea testing service specification template for commissioners, and a tool which supports decisions on gonorrhoea testing by estimating positive predictive values (PPVs) by clinical setting in each local authority in England [3].

3.1 References

1. PHE (August 2014). Guidance for the detection of gonorrhoea in England: including guidance on the use of dual nucleic acid amplification tests (NAATs) for chlamydia and gonorrhoea, PHE website.
2. Field N, Kennedy I, Folkard K, Ison C, Duffell S and Hughes G: results from a national survey of local authority commissioners (in press).
3. All documents are available from the PHE “Guidance for the detection of gonorrhoea in England ” website page: https://www.gov.uk/government/publications/guidance-for-the-detection-of-gonorrhoea-in-england.

4. EVD in west Africa: PHE guidance documents for health professionals

The following guidance documents for UK health professionals relating to the Ebola virus disease (EVD) outbreak in west Africa were added to the PHE website during the past week. All can be accessed via the Health Protection Collection “Ebola virus disease: clinical management and guidance” landing page [1]:

• updated guidance, produced by the Advisory Committee on Dangerous Pathogens, on the management of viral haemorrhagic fevers (VHF) [2]. This includes information on the risk assessment of patients, infection control and prevention, laboratory testing, and public health actions. Associated with this guidance is an updated risk assessment algorithm [2] that should be used in conjunction with the guidance document;
• guidance for doctors (from PHE Microbiology Services) seeking advice on testing samples from patients with possible VHFs [3];
• guidance for clinical staff undertaking direct patient care in acute trusts to assist them in identifying and managing patients who require assessment for EVD [4];
• environmental cleaning guidance for potential Ebola contamination (excluding healthcare settings) [5];
• guidance for educational, childcare and young persons’ settings where there may be children or students returning or visiting from Ebola-affected countries [6].

PHE’s National Travel Health Network and Centre updated its advice for health professionals on 12 August 2014 [7].

4.1 References

1. “Ebola virus disease: clinical management and guidance”, as at 18 August 2014.
2. Viral haemorrhagic fever: ACDP algorithm and guidance on management of patients (updated 13 August 2014).
3. Viral Haemorrhagic Fever Sample Testing Advice (15 August 2014).
4. Ebola virus disease: identifying and managing patients for assessment in acute trusts (15 August 2014).
5. Ebola: environmental cleaning guidance for potential contamination (excluding healthcare settings) (13 August 2014).
6. Ebola: advice and risk assessment for educational, childcare and young persons’ settings (13 August 2014).
7. National Travel Health Network and Centre Clinical Update (8 August 2014), http://nathnac.org/pro/clinical_updates/ebola_westafrica_120814.htm.