Final Issue: Volume 16 Number 51	Published on: 21 December 2006	Final Issue in PDF PDF format (283 Kb)

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• Hospital-associated transmission of Panton-Valentine Leukocidin (PVL) positive community-associated MRSA in the West Midlands
• New variant of Chlamydia trachomatis reported in Sweden: implications for diagnostic laboratories in the United Kingdom
• Confidential study of deaths following healthcare-associated infection (HCAI) and linkage of surveillance and mortality data – first year update
• Imported chikungunya in the United Kingdom
• Changing face of CDR Weekly
• Advisory Committee on Antimicrobial Resistance and Healthcare Associated Infections (ARHAI) – vacancies for a Chair and 14/15 expert members and one lay member
  
  

Hospital-associated transmission of Panton-Valentine leukocidin (PVL) positive community-associated MRSA in the West Midlands

Eight cases of Panton-Valentine leukocidin (PVL) positive community-associated MRSA (CA-MRSA) have been identified among individuals in a hospital and their close household contacts in the West Midlands. Four individuals developed an infection, two of whom died. Transmission of the CA-MRSA strain appeared to have occurred on two separate wards and went undetected until a fatal case was examined in detail. Although the occurrence of several different clones of CA-MRSA has been reported previously [1], this is the first documented report of nosocomial transmission of PVL-positive CA-MRSA in the United Kingdom (UK).

A previously healthy healthcare worker (HCW) developed an MRSA sepsis, septic shock, pneumonia and died following non-elective surgery in September 2006 (case 1). Screening of patients and staff on ward A where case 1 worked revealed another HCW carrying the same strain (case 2). This HCW had a history of skin abscesses due to MRSA and was a social contact of case 1. Four household contacts of cases 1 and 2 were found to carry the same strain (cases 3 to 6). One of these, case 5, worked as a HCW on a different ward (ward B). Subsequent screening of both patients and staff on ward B revealed another HCW working on ward B carrying the same strain (case 7). This individual had a four month history of recurrent infection of the eye lids. One further case was identified in March 2006 through retrospective analysis of MRSA isolates kept in the laboratory. The patient (case 8) developed a suspected hospital-acquired pneumonia while in ward A and died within 24 hours of the blood culture being taken that grew the organism. Extensive healthcare and community-based contact tracing has not identified further cases.

The most prevalent hospital and healthcare-associated MRSA strains found in UK healthcare settings are epidemic MRSA (EMRSA) 15 and 16, both of which are negative for PVL and usually resistant to ciprofloxacin. The MRSA strain responsible for this outbreak was susceptible to all non-beta-lactam antibiotics tested (including ciprofloxacin), positive for the PVL genes and resembled closely the South West Pacific CA-MRSA clone (multilocus sequence type ST30) [1,2]. Data from the national Staphylococcus Reference Laboratory show this is the fifth most common clone of CA-MRSA seen in England and Wales, with 13 cases of skin and soft tissue infection (SSTI) identified in 2005. This outbreak heralds the first report of nosocomial transmission and known deaths due to this strain in England and Wales.

In recent years CA-MRSA has emerged as an important pathogen among previously healthy young people in community settings worldwide. In addition to causing sporadic disease in the community, outbreaks of CA-MRSA have occurred in individuals in close contact, particularly where skin trauma is likely, for example sporting teams, military recruits and injecting drug users. Many strains of CAMRSA encode PVL, a poreforming cytotoxin associated with necrotic lesions or abscess formation in SSTI [3]. More rarely, infection can lead to cases of serious, life-threatening disease such as necrotising pneumonia, necrotising fasciitis and purpura fulminans which may prove fatal [3].

A recent review [4] identified 12 reports world-wide documenting nosocomial transmission of various clones of CA-MRSA. This change in the epidemiology of MRSA demands increased vigilance among healthcare personnel. To enhance the case ascertainment of PVL-positive CA-MRSA in the healthcare and community setting, we would encourage the submission of samples from patients presenting with SSTIs (particularly boils, furuncles and abscesses, especially where they are recurrent) for microbiological testing. In conjunction with this, we recommend microbiologists test MRSAs for susceptibility to ciprofloxacin as a marker of putative CA-MRSA since the majority of healthcare-associated MRSA are resistant to ciprofloxacin [1]. All ciprofloxacin sensitive MRSAs, accompanied by relevant clinical information, should be referred to the Staphylococcus Reference Laboratory (Centre for Infections, HPA, 61 Colindale Avenue, London, NW9 5EQ) for characterisation including PVL testing to determine if they are CA-MRSA.

References
1. Health Protection Agency. Community MRSA in England and Wales: definition through strain characterisation. Comm Dis Rep CDR Wkly [serial online] 2005; 15 (11): News. Available at <http://www.hpa.org.uk/cdr/archives/2005/cdr1105.pdf>.

2. Robinson DA, Kearns AM, Holmes A, Morrison D, Edwards G, O'Brien FG, et al. Re-emergence of early pandemic Staphylococcus aureus as a community-acquired meticillin-resistant clone. Lancet 2005; 365 (9466):1256-8.

3. Chief Medical Officer. Interim guidance on diagnosis and management of PVL-associated Staphylococcal infections in the UK. London, DH, 12 April 2006. Available from <http://www.dh.gov.uk/AboutUs/MinistersAndDepartmentLeaders/ChiefMedicalOfficer/Features/ Features Article/fs/en?CONTENT_ID=4133761&chk=oW8s4w>.

4. Otter JA, French GL. Nosocomial transmission of community-associated meticillin-resistant Staphylococcus aureus: an emerging threat. Lancet Infect Dis 2006; 6:753-5.

 

New variant of Chlamydia trachomatis reported in Sweden: implications for diagnostic laboratories in the United Kingdom

A new variant Chlamydia trachomatis strain has been isolated in Sweden [1,2]. Certain commercial diagnostic platforms generate false negative results when screening specimens from patients who are infected with the new variant strain. The Chlamydia trachomatis cryptic plasmid (a nonchromosomal genetic element with unknown function found in all C. trachomatis strains) is high copy number and as such, is a popular target for commercial diagnostic platforms. This new strain has a 377bp deletion in a portion of the plasmid that is the target area for the C. trachomatis NAAT tests manufactured by Abbott and Roche. Consequently these Platforms, which remain unaffected by this deletion, are the Aptima Combo 2 (AC2: Genprobe), RealArt CT Kit (Artus), and the Strand Displacement Assay (SDA) (Probetec, Becton Dickinson), as they target rRNA, the omp gene and a different region of the cryptic plasmid, respectively. In Sweden, the majority of laboratories were using a Roche platform whereas information obtained from the National External Quality Assessment Scheme (NEQAS) programme showed 39% of laboratories reporting to the scheme in the United Kingdom (UK) are currently using the Roche/Abbott platforms for the detection of C. trachomatis. The length of time that this new variant has been circulating undiagnosed in the Swedish community is, as yet undetermined, although recent decreases in C. trachomatis infections have been observed and consequently concerns are that the strain is widely distributed throughout the country. There is currently no evidence that the new C. trachomatis variant is present within the UK. Indeed a recent large-scale study: the C. trachomatis NAAT evaluation programme screened 2375 urine specimens (of which 595 were positive and 131 were discordant), collected from patients attending at one of three geographically diverse sites in the UK, using four commercial platforms in a direct head-to-head comparison. Of the discordant specimens, only three urine specimens where found to be reproducibly negative on the Roche Cobas platform and positive on both the SDA and AC2 platforms. Differences in specimen status could also, however, be explained by differences in analytic sensitivity for the three platforms rather than a missing target region.

Current Recommendations to Diagnostic Laboratories in England and Wales

• Laboratories performing testing on two platforms, including either the Roche or Abbott tests, should consider using the Roche or Abbott tests for confirmation rather than primary testing;
• Laboratories who are using Roche or Abbott platforms as their only method of C. trachomatis detection should carry on using this approach but be vigilant for obvious decreases in the number of positives cases;
• All laboratories should look for new alerts containing updated information.

The Sexually Transmitted Bacteria Reference Laboratory (STBRL) is happy to assist with any local problems or discuss potential discrepant results that may be due to the variant strain: email stbrl@hpa.org.uk

Future studies

STBRL, in collaboration with the European Surveillance of Sexually Transmitted Infections (ESSTI, www.essti.org) collaborative group, is currently investigating this new variant strain. The following strategies will be employed to determine the whether the new variant is present within the UK/Europe and if it is, ascertain its prevalence.

• Investigation of the presence of this variant in samples from different geographical locations across Europe.
• Perform trend analyses to identify unexpected decreases in the number of positive cases of C. trachomatis.

All findings will be made available as soon as possible.

 

References
1 Ripa T, Nilsson P. A variant of Chlamydia trachomatis with deletion in cryptic plasmid: implications for use of PCR diagnostic tests. Eurosurveillance 2006; 11(11), Available at <http://www.eurosurveillance.org/ew/2006/061109.asp#2>.

2. Soderblom T, Blaxhult, Fredlund H, Hermann B. Impact of a genetic variant of Chlamydia trachomatis on national detection rates in Sweden. Eurosurveillance 2006; 11(12) Available at <http://www.eurosurveillance.org/ew/2006/061207.asp#>.

 

Confidential study of deaths following healthcare-associated infection (HCAI) and linkage of surveillance and mortality data – first year update

The joint project by the Health Protection Agency (HPA) and Office for National Statistics (ONS) to further understanding of mortality following MRSA infection, has reported on the progress made in establishing robust methods for both the linkage and investigation of deaths in its first year [1]. The two year project commenced in August 2005 with funding from the Department of Health [2].

The pilot phase of the data linkage study investigated whether infection records held by the HPA could be reliably linked to mortality records held by ONS. The lack of a well completed, unique identifier in infection records meant deterministic record linkage could not be applied and a probabilistic method was developed [3]. The method was developed and trialled using invasive Streptococcus pneumoniae infection records sampled from reports made between 1 July 2003 and 30 June 2004 linked to mortality records from 1 July 2003 to 31 March 2005. These same S. pneumoniae records were submitted to the NHS Central Register (NHSCR) Tracing Service for evaluation of the linkage mechanism by providing information on outcome from an independent source. Reports of invasive S. pneumoniae infections were used in this work because they contain full surname data (which MRSA data do not) which is required to enable matching by the NHSCR. Both methods were shown to be of similar accuracy with respect to identifying individuals who had died following infection.

Following the successful development of a probabilistic method for the linking of infection and mortality records, the method is now being used to link MRSA infection records to mortality records to enable analyses of mortality following invasive MRSA infection and certification of cause of death for these patients.

The pilot phase of the National Confidential Study of Deaths Following Healthcare-Associated Infection is a qualitative clinical review of patients who have died following an MRSA infection, to describe and evaluate the relative importance of key events leading up to death.

Cases for the pilot phase were identified retrospectively from a random sample of death registrations with any mention of MRSA on the death certificate. Nine hospitals were visited by the study investigator and 18 patients reviewed. The data collated comprised a review of medical records, interviews with infection control staff, and consultants responsible for the patients, as well as a questionnaire to gather organisational data on the management of infection control. All data were reviewed by an independent multidisciplinary panel of six clinical experts specifically convened for the study, with the aim of reaching a consensus on the relative contribution of different factors, in particular the MRSA infection, to the patient’s death [4].

The main phase of the Study will use the same methods to review a small sample of patients drawn from the linked data (ie patients with invasive MRSA infection who subsequently die in hospital). Unlike the pilot phase, sampling of cases is carried out independently of whether MRSA was documented on the death certificates.

For further information on the Data Linkage Study or Confidential Study of Deaths following HCAI please contact Nicola Potz (nicola.potz@hpa.org.uk) or David Bridger (david.bridger@hpa.org.uk), respectively, at the Department of Healthcare Associated Infection and Antimicrobial Resistance, Health Protection Agency Centre for Infections, London.

 

References
1. Health Protection Agency, Office for National Statistics. National Confidential Study of Deaths Following Healthcare Associated Infection & HPA/ONS Data Linkage Study. Year 1 report (01/08/05 to 31/07/06). London: Health Protection Agency, 2006.

HPA. New initiative to link surveillance and mortality data. Commun Dis Rep CDR Wkly [serial online] 2005; 15(37):News. Available at <http://www.hpa.org.uk/cdr/archives/2005/cdr3705.pdf>.

Potz N, Powell D, Pebody R, Lamagni T, Bridger D, Duckworth G. Development of a method to link infection and mortality data. Poster presentation. Health Protection Agency Annual Conference; Sept. 2006; Warwick.

Bridger D, Pebody R, Lamagni T, Wilson J, Powell D, Potz N, et al. Methodology for the National Confidential Study of Deaths Following Healthcare Associated Infection. Poster presentation. Health Protection Agency Annual Conference; Sept. 2006; Warwick.

 

Imported chikungunya in the United Kingdom

Between 1 January and 31 October 2006, 106 cases with evidence of chikungunya infection, have been reported by the HPA Special Pathogens Reference Unit (SPRU). Of those, 29 have been laboratory confirmed (PCR and/or virus isolation), 29 are probable cases (clinical symptoms and IgG, IgM positive), 33 are classified as suspected cases (clinical symptoms, relevant travel history and IgG positive), and 15 have had a past exposure (IgG positive with no clinical details or travel history, or IgG positive with history of past exposure).

Of the total, 67 cases reported travel to the Indian Ocean islands (57 to Mauritius , six to the Seychelles , and four to Madagascar ), where a large outbreak was reported earlier in the year [1]. These cases were received at SPRU between 2 March and 31 August 2006, and the outbreak has since declined. Twenty cases (received at SPRU between 30 May and 26 October 2006) reported recent travel to India , where an outbreak began in February 2006 [2]. Over a million suspected cases have been reported in India since the outbreak began, with 1831 cases confirmed. As of 12 December 2006, twelve of the country's 31 states have been affected of which, Karnataka (298 confirmed, 762,026 suspected cases) and Maharashtra (774 confirmed, 268,321 suspected cases) have been most affected. Other states affected have been Andhra Pradesh, Tamil Nadu, Madhya Pradesh, Gujarat, Kerala, Andaman and Nicobar Islands, Government of National Capital Territory of Delhi, Rajasthan, Pondicherry , and Goa [3] . Further to this, an outbreak of suspected chikungunya has also been reported in Sri Lanka [4], although as of 31 October, no cases of chikungunya, related to travel to Sri Lanka , have been received by the SPRU.

Nearly 800,000 United Kingdom residents travelled to India in 2005, a 21% increase compared to 2004 [5]. Although the chikungunya outbreak appears to be in decline [6], travellers to India and Sri Lanka should be aware of the risk of infection, which is transmitted by mosquitoes of the Aedes species (the same mosquito that transmits dengue fever, which is also prevalent in India ). Aedes mosquitoes are active during daylight hours (particularly around dusk and dawn) and prevention relies on bite avoidance. Further information about this can be found on the National Travel Health Network and Centre (NaTHNaC) website at <http://www.nathnac.org/pro/factsheets/iba.htm>.

Further information about chikungunya can be found on the HPA website at <http://www.hpa.org.uk/infections/topics_az/Chikungunya/default.htm>.

 

References
1. HPA. Chikungunya: increase in imported cases. Commun Dis Rep CDR Wkly 2006 [accessed 12 December 2006]; 16 (21): news. Available at <http://www.hpa.org.uk/cdr/archives/2006/cdr2106.pdf>.

2. World Health Organization Epidemic and Pandemic Alert and Response (EPR). [online]. Chikungunya in India, 17 October 2006. [Accessed 12 December 2006]. Available at <http://www.who.int/csr/don/2006_10_17/en/index.html>.

3. National Vector Borne Disease Control Programme. Chikungunya fever situation in the country during 2006 (As on 12.12.2006). [online] [Accessed 12 December 2006]. Government of India Ministry of Health and Family Welfare Available at <http://www.namp.gov.in/Chikun-cases.html>.

4. NaTHNaC. Suspected Chikungunya virus – Sri Lanka . Clinical update: 28 November 2006 [online] [accessed 12 December 2006]. Available at <http://www.nathnac.org/pro/clinical_updates/chik_281106.htm>.

5.Office for National Statistics. The International Passenger Survey, Travelpac dataset 2005 . [online] London: ONS, 2006. Available at <http://www.statistics.gov.uk/statbase/Product.asp?vlnk=14013>.

6.Government of India , Ministry of Health and Family Welfare. Update on Chickungunya. 13 October 2006. Available at <http://www.namp.gov.in/Doc/Chikungunya%20-%20Update.pdf>.

 

Changing face of CDR Weekly

From 5 January 2007 the Communicable Disease Report (CDR) Weekly will be superseded by a new publication, the Health Protection Report (HPR) Weekly, to reflect the full range of the Health Protection Agency’s work. HPR Weekly will retain all the content currently available in CDR Weekly, with the addition of information on chemicals, radiation, and emergency planning. These will each be represented initially by quarterly reports, as well as in news and current events. Publication will be at 10:00 on Friday morning, rather than on Thursday evening. The full content of CDR will remain available online, and be fully linked to from HPR.

 

Advisory Committee on Antimicrobial Resistance and Healthcare Associated Infections (ARHAI) – vacancies for a Chair and 14/15 expert members and one lay member

Expert advice to Government on antimicrobial resistance and healthcare associated infections is currently provided though two different committees: the Specialist Advisory Committee on Antimicrobial Resistance (SACAR) and the Steering Group on Healthcare Associated Infection (SGHCAI).

The Department of Health now plans to establish a new independent body to advise across both areas, providing integrated and more streamlined advice in these two interrelated fields. This new Advisory Non-Departmental Public Body will be known as the Advisory Committee on Antimicrobial Resistance and Healthcare Associated Infections (ARHAI), and has vacancies for a chair and up to 15 expert and one lay member. These are public appointments, not employment, and although no fees are payable, travelling expenses and subsistence allowances will be paid.

Further information is available on the HPA website at <http://www.hpa.org.uk/infections/topics_az/hai/ARHAIadvert.pdf>.