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PAPERS: David H Wyllie, Tim E A Peto, and Derrick Crook MRSA bacteraemia in patients on arrival in hospital: a cohort study in Oxfordshire 1997-2003 BMJ 2005; 331: 992 [Abstract] [Full text]

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Enhanced MRSA bacteraemia surveillance

Judith A Bowley, Martin Kiernan, Karen Allen, Rizwan Khan, Maire O'Donoghue, Moira Taylor, Rachel Sen, Alan Wills, Catherine Quigley   (29 September 2005)

What is the significance of MRSA isolated from blood cultures taken in acute hospital admissions?

Barry Neish, Thomas Gillespie, Kenneth G. Liddell   (5 October 2005)

The significance of MRSA isolated from blood cultures taken in acute hospital admissions

David H Wyllie, Derrick W Crook, Timothy E A Peto   (9 October 2005)

What is the significance of MRSA isolated from blood cultures taken in acute hospital admissions?

Barry Neish, Thomas Gillespie, Kenneth G. Liddell   (14 October 2005)

Contaminant blood cultures

Roman Romero-Ortuno, TW7 6AF   (29 October 2005)

MRSA surveillance in health care establishments

Subhash C. Arya, Subhash C. Arya, Nirmala Agarwal   (2 November 2005)

Improving MRSA bacteraemia rates requires better surveillance and defining the source of infection

Mark Melzer   (15 November 2005)

Enhanced MRSA bacteraemia surveillance 29 September 2005
Judith A Bowley, Consultant Microbiologist Southport and Ormskirk NHS Trust, Town Lane Kew, Southport, Merseyside. PR8 6PN, Martin Kiernan, Karen Allen, Rizwan Khan, Maire O'Donoghue, Moira Taylor, Rachel Sen, Alan Wills, Catherine Quigley Send response to journal: Re: Enhanced MRSA bacteraemia surveillance	Wyllie et al1 concluded that admission cultures accounted for 24% of total hospital Methicillin Resistant Staphylococcus aureus bacteraemia episodes over a period of seven years to March 2004. Data collected from five district general hospitals and one university hospital within Cheshire and Merseyside and one district general hospital within Greater Manchester would support this view. Enhanced MRSA bacteraemia surveillance data has been collected, using published case definitions2, by this group of hospitals since April 2004. Anonymised data is collected on paper forms and analysed using the FORMIC data capture system. Five hundred and thirty four cases of Staphylococcus aureus bacteraemia were identified between April 2004 and March 2005. There have been 334 cases of Methicillin Sensitive Staphylococcus aureus bacteraemia and 200 cases of MRSA bacteraemia during this 12-month period. Sixty six (33%) of the MRSA bacteraemia cases occurred within 48 hours of arrival in hospital. Of these 66 cases, 16 (24%) were related to a previous hospital admission, 25 (38%) were patients known to have been previously colonised with MRSA and 13 (20%) were admissions from nursing or residential homes. Thirty five (53%) of cases were admitted as medical specialities of which 25 (71%) were over 65 years of age. Empirical antibiotic policies do not usually reflect community acquired MRSA bacteraemia. Our results support the suggestion by Wyllie et al1 that anti-MRSA treatment should be considered for patients with possible staphylococcal sepsis who have previously been hospitalised or known to be colonised with MRSA. In a predominantly district general hospital setting, anti-MRSA treatment should also be considered for possible staphylococcal sepsis in elderly medical admissions and admissions from nursing homes. 1. Wyllie DH, Peto TEA, Crook D. MRSA bacteraemia in patients on arrival in hospital: a cohort study in Oxfordshire 1997-2003. BMJ, doi: 0.1136/bmj.38558.453310.8F (9 September 2005) 2. Health Protection Agency Communicable Diseases Surveillance Centre for the Department of Health. MRSA surveillance system-results. www.dh.gov.uk/PublicationsAndStatistics/Publications/Publica tionsStatistics /PublicationsStatisticsArticle/fs/en? CONTENT_id=4085951&chk=HBt2QD Competing interests: None declared
What is the significance of MRSA isolated from blood cultures taken in acute hospital admissions? 5 October 2005
Barry Neish, Trainee Clinical Scientist Wishaw General Hospital, 50 Netherton Street, Wishaw, ML2 0DP, Thomas Gillespie, Kenneth G. Liddell Send response to journal: Re: What is the significance of MRSA isolated from blood cultures taken in acute hospital admissions?	Wyllie et al1 recommended that patients presenting with admission meticillin resistant Staphylococcus aureus bacteraemia, accounting for 24% of all MRSA bacteraemias, require immediate consideration for vancomycin treatment. All positive blood cultures taken in acute admissions at this hospital over a three-year period were investigated. Microbiology laboratory results, case notes, notes taken by the infection control nurses and reports to Health Protection Scotland of blood borne infections were used to determine if these infections were genuine. Total number of Staphylococcus aureus bacteraemias during the study period was 244, with 65 in acute admissions. The number of MRSA bacteraemias during the study period was 112, with 24 in acute admissions, which accounted for 18.75% of all hospital MRSA bacteraemias. Seventeen patients (81%) had been admitted from a nursing home/other hospital or had recently had an inpatient hospital stay (less than 6 months previously). The contamination rate from all blood cultures for accident and emergency was 49% over the three-year period. A significant proportion (50%) of MRSA from blood cultures, in patients newly admitted to hospital, were not suggestive of generalised infection. The source of the MRSA could be skin colonisation of the patient contaminating the blood cultures, or even the medical or nursing staff taking the blood cultures in the hectic environment of acute admissions. The 49% contamination rate for all blood cultures in accident and emergency further supports these results. These data highlight the fact that the interpretation of blood culture results should be taken in context with the patient’s general condition, subsequent progress and the patient’s MRSA status determined by screening. 1Wyllie DH, Peto TEA, Crook D. MRSA bacteraemia in patients on arrival in hospital: a cohort study in Oxfordshire 1997-2003. BMJ, doi:0.1136/bmj.38558.453310.8F (9 September 2005) Competing interests: None declared
The significance of MRSA isolated from blood cultures taken in acute hospital admissions 9 October 2005
David H Wyllie, Clinical Lecturer in Microbiology Nuffield Department of Clinical Laboratory Sciences, University of Oxford OX3 9DU, Derrick W Crook, Timothy E A Peto Send response to journal: Re: The significance of MRSA isolated from blood cultures taken in acute hospital admissions	We note the experience of Neish et al, in whose centre half cases of admission MRSA blood culture isolation were considered not suggestive of generalised infection. We have described the relationship between inflammatory marker concentrations and bacteraemia in a consecutive series of 21,495 acute medical emergency admissions between 1999 and 2001 1 2. Among the 5,964 cases who had blood cultures taken, the contamination rate was 9.2%, and there were 530 cases of significant bacteraemia 1. Included were 58 cases of methicillin sensitive S. aureus and 19 of methicillin resistant S. aureus (MRSA), cases which form a subset of the patients in our recent publication 3. The distribution of neutrophil, lymphocyte counts and C-reactive protein concentrations on arrival in the 19 cases of admission MRSA bacteraemia is shown below. [Lymphocytes] X 109/L 0-0.5 0.5-1.0 1.0-1.5 1.5-2.0 Total CRP, mg/L Not done 1 1 2 0 4 <8-49 1 0 0 0 1 50-99 0 1 1 1 3 100-149 0 1 0 0 1 150-199 1 2 0 1 4 200-249 0 1 0 0 1 249-284 1 1 0 0 2 >=285 2 0 1 0 3 Total 6 7 4 2 19 [Lymphocytes] X 109/L 0-0.5 0.5-1.0 1.0-1.5 1.5-2.0 Total [Neutrophils] X 109/L 1.0-4.9 2 0 0 0 2 5.0-9.9 1 2 1 1 5 10.0-14.9 2 1 0 1 4 15.0-19.9 0 0 1 0 1 >=20.0 1 4 2 0 7 Total 6 7 4 2 19 We interpret these data, together with our published analyses 1 2, as evidence of systemic inflammation compatible with bacteraemia in almost all the cases; we doubt that substantial numbers of the cases of admission MRSA blood stream isolation we have reported3 are due to contamination. We are not aware of prospective studies examining how best to ascribe MRSA blood culture isolates to contamination. In view of studies describing frequent occult deep foci of infection in cases of community-acquired S. aureus bacteraemia4, substantial associated mortality5, and difficulties with clinical assessment of bacteraemia in the elderly 6, withholding treatment given blood stream MRSA isolation is a step we take with great caution. We might consider MRSA blood culture isolates contaminants in cases who, after inpatient observation, showed no clinical illness, persistent absence of biochemical and haematological evidence of inflammation, and had repeated negative follow-up blood cultures in the absence of antibiotic therapy. 1. Wyllie DH, Bowler IC, Peto TE. Relation between lymphopenia and bacteraemia in UK adults with medical emergencies. J Clin Pathol 2004;57(9):950-5. 2. Wyllie DH, Bowler IC, Peto TE. Bacteraemia prediction in emergency medical admissions: role of C reactive protein. J Clin Pathol 2005;58(4):352-6. 3. Wyllie DH, Peto TE, Crook D. MRSA bacteraemia in patients on arrival in hospital: a cohort study in Oxfordshire 1997-2003. Bmj 2005. 4. Jensen AG. Importance of focus identification in the treatment of Staphylococcus aureus bacteraemia. J Hosp Infect 2002;52(1):29-36. 5. McClelland RS, Fowler VG, Jr., Sanders LL, Gottlieb G, Kong LK, Sexton DJ, et al. Staphylococcus aureus bacteremia among elderly vs younger adult patients: comparison of clinical features and mortality. Arch Intern Med 1999;159(11):1244-7. 6. Chassagne P, Perol MB, Doucet J, Trivalle C, Menard JF, Manchon ND, et al. Is presentation of bacteremia in the elderly the same as in younger patients? Am J Med 1996;100(1):65-70. Competing interests: None declared
What is the significance of MRSA isolated from blood cultures taken in acute hospital admissions? 14 October 2005
Barry Neish, Trainee Clinical Scientist Wishaw General Hospital, 50 Netherton Street, Wishaw, ML2 0DP, Thomas Gillespie, Kenneth G. Liddell Send response to journal: Re: What is the significance of MRSA isolated from blood cultures taken in acute hospital admissions?	We note the response of Wyllie et al and wish to make certain clarifications. Firstly, it should be noted that the contamination rate quoted (of 49%) was of the total positive blood cultures. The contamination rate of all blood cultures sent from acute admissions was 5.8% over the three-year study period. This figure is in agreement with those of Wyllie et al. Secondly, since this was a purely retrospective study, the question of whether vancomycin should or should not have been given when meticillin resistant Staphylococcus aureus bacteraemia was suspected, is academic. We do recommend that vancomycin treatment may be stopped early should the available evidence point to colonisation rather than infection. Competing interests: None declared
Contaminant blood cultures 29 October 2005
Roman Romero-Ortuno, SHO in Care of the Elderly West Middlesex University Hospital, TW7 6AF Send response to journal: Re: Contaminant blood cultures	Dear Editor The definition of "case of MRSA bacteriaemia” as "isolation of MRSA from blood cultures" lacks accuracy. On-the-ground experience as a junior doctor on the medical wards teaches that, in many cases, the isolation of MRSA in blood cultures has no clinical correlation. The usual advice from hospital microbiologists following such an event is that, should the patient be well and his inflammatory markers down, the result is likely to be a "contamination" and no treatment is needed but observation. The scenario is not infrequent and implies that the hospital concerned will have to report (and perhaps be accountable for) an MRSA bacteriaemia that in fact never occurred in the first place. The detection of MRSA bacteriaemia by means of blood cultures is bound to yield false positive results. Standards published by the American Society of Microbiology indicate that the rate of contaminant blood cultures should not exceed 3%, but there is evidence that the contamination rate in many university hospitals exceeds 6% [1]. The economic consequences of contaminant blood cultures have been well established [2], but in the current days of the NHS, the political and mediatic consequences of too many "MRSA bacteriaemiae" could prove dramatic for many trusts. It is of utmost importance that blood culture contamination be minimised, especially so when it comes to "superbugs". The use of blood cultures is often suboptimal. In many NHS Trusts, there are not clear guidelines with regards to the correct indications and technique of blood culture-taking. Although aseptic technique is critical to obtain reliable results, it is infrequently taught and audited. Notably, nurses, medical students and house staff, who are most likely to order and/or obtain blood cultures, lack key blood cuture-related knowledge [1]. Skin cleaning is often incomplete, and many attendants still palpate with non-sterile gloves the venipuncture site before needle insertion. “The cleanest man shall be not the one who cleans the most, but the one who dirties the least” (Traditional Spanish proverb) References: [1] Parada JP, Schwartz DN, Schiff GD, Weiss KB. Effects of type and level of training on variation in physician knowledge in the use and acquisition of blood cultures: a cross sectional survey. BMC Infect Dis. 2005 Sep 15;5:71. [2] Bates DW, Goldman L, Lee TH: Contaminant blood cultures and resource utilization: the true consequences of false-positive results. JAMA 1991, 265:365-69. Competing interests: None declared
MRSA surveillance in health care establishments 2 November 2005
Subhash C. Arya, Clinical Microbiologist Sant Parmanand Hospital, 18 Alipore Road, Delhi- 110054, Subhash C. Arya, Nirmala Agarwal Send response to journal: Re: MRSA surveillance in health care establishments	To the Editor: __ Wyllie et al (1) point to hurdles in selection of drugs for any suspected MRSA patients reporting in hospitals. Without any prejudice towards the efficacy or cost of aminoglycosides, Linezolid and glycopeptides (1), clindamycin, a lincosamide, might well be the ideal recipe. Clindamycin addressed during 2004 at least two MRSA episodes in a surgical intensive care unit in a 140-bedded tertiary care hospital in the Indian Capital metropolis.[2] Low-cost clindamycin should better be considered at the primary therapeutic intervention against any possible MRSA episodes when the facilities for bacterial cultures were not available in any health care establishment. Last but not least, the patient’s MRSA might well turn out to be susceptible to the lincosamide. Clindamycin would appear to have the potential on emerging as the Achilles Heal, prophylactic or therapeutic, in innumerable countries where culture facilities for a rapid MRSA label were not likely for a considerable period. ARYA, Subhash C. AGARWAL, Nirmala, FRCOG Sant Parmanand Hospital, 18 Alipore Road, Delhi- 110054, India Email subhashji@hotmail.com References: 1.Wyllie DH, Peto TEA, Crook D. MRSA bacteraemia in patients on arrival in hospital: a cohort study in Oxfordshire 1997-2003. BMJ, doi; 10.1136/bmj.453310.8F [published 9September 2005] 2. Arya SC, Kapoor S, Agarwal N, Bhasin R, George S. Comments on use of a disk diffusion method with cefoxitin (30µG) to detect of methicillin- resistant Staphylococcus aureus. Eur J Clin Microbiol Infect Dis 2004; 23: 867-868 Competing interests: None declared
Improving MRSA bacteraemia rates requires better surveillance and defining the source of infection 15 November 2005
Mark Melzer, Consultant Microbiologist Department of Microbiology, King George Hospital, Barley Lane, Goodmayes, Essex IG3 8YB Send response to journal: Re: Improving MRSA bacteraemia rates requires better surveillance and defining the source of infection	I read with interest the recent articles concerning MRSA bacteraemia (1-3). Since June 2003, at King George Hospital, Barking Havering and Redbridge trust, we have prospectively collected enhanced surveillance data on patients with MRSA bacteraemia. We document whether infection is hospital or community acquired, speciality and ward at time of bacteraemia, infection sites, presence of shock, delays in administrating appropriate antibiotics and clinical outcomes. 36/136 (26%) of MRSA blood stream isolates were community-acquired and the majority 32/36 (89%) had antibiograms typical of EMRSA-15 and EMRSA-16, probably acquired through previous hospital contact. Many of these isolates were skin contaminants, 17/36 (47%), and 16 of these patients survived without specific MRSA treatment. 4/36 (11%) had community-acquired bacteraemia secondary to infected central intravascular catheters; none of these patients were shocked at presentation and they survived despite delays in initiating teicoplanin. While I agree that community-acquired MRSA bacteraemia should be removed from mandatory surveillance (it fails to reflect the effectiveness of hospital infection control policies) I do not believe that empirical glycopeptide treatment is routinely required for community- acquired sepsis. In hospital-acquired cases, although it is important to record the wards where MRSA bacteraemia occurs, it is essential to define sites of infection causing bacteraemia, most commonly intravascular catheters or surgical wounds (4). This informs infection control teams and the Director of Infection Prevention and Control how best to reduce MRSA bacteraemia rates. At King George Hospital, 15/100 (15%) of our hospital-acquired MRSA bacteraemias occurred on medical wards and were caused by infected venflon site infections. Although the majority of these patients recovered, 12/15 (80%), many suffered painful infections that prolonged their hospital stay. As suggested in ‘Winning Ways’ (5), we are piloting a system whereby all peripheral venflons are automatically removed after 3 days. Whether, together with selective screening, isolation, cohorting and topical decolonisation of patients, we can achieve an arbitrary government target of a ‘50% reduction in MRSA bacteraemia by 2008’ remains to be seen. References: (1) Wyllie DH, Peto TEA, Crook D. MRSA bacteraemia in patients on arrival in hospital: a cohort study in Oxfordshire 1997-2003. BMJ 2005; 331:992-5 (2) Duckworth G, Charlett A. Improving surveillance of MRSA bacteraemia. BMJ 2005; 331:976-7 (3) Spiegelhalter DJ. Problems in assessing rates of infection with methicillin resistant Staphylococcus aureus. BMJ 2005; 331:1013-5 (4) Melzer M, Eykyn SJ, Gransden WR, Chinn S. Is MRSA more virulent than MSSA? A comparative cohort study of British patients with nosocomial infection and bacteraemia. Clin Infect Dis 2003; 37(11):1453-60 (5) Winning ways: working together to reduce healthcare associated infection in England, Department of Health, 2003. Competing interests: None declared