QJM Advance Access originally published online on September 19, 2008
QJM 2008 101(11):889-898; doi:10.1093/qjmed/hcn114
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Development, impact and outcomes of the Hull Bacteraemia Service
From the 1Department of Infection and Tropical Medicine, 2Department of Medical Microbiology and 3Department of Pharmacy, Hull and East Yorkshire Hospitals NHS Trust, Hull, UK
Address correspondence to Dr Gavin Barlow, Department of Infection and Tropical Medicine, Castle Hill Hospital, Hull and East Yorkshire Hospitals NHS trust, Cottingham, East Yorkshire HU16 5JQ, UK. email: gavin.barlow{at}hey.nhs.uk
Received 3 July 2008 and in revised form 19 August 2008
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Summary |
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Background: Bacteraemia is a significant cause of mortality and healthcare expenditure. Evidence suggests that consultation by an infection specialist may improve outcomes.
Aim: To review the characteristics and outcomes of patients seen by a newly implemented bacteraemia service.
Methods: Retrospective review of data collected at time of consultation. Economic analyses and benchmarking of outcomes were also performed.
Results: One hundred and fifty-one patients were seen by the service over an 18-month period. Staphylococcus aureus was the most common isolate and central venous lines the most common source. Antibiotics were changed and additional investigations suggested in 62% and 61% of patients, respectively. The 30-day mortality was 19%. Implementation and delivery of the service over the 18-month study period cost £22 663 (£15 109 per year). The cost per change in antibiotic prescription was £244. The cost per ‘near-miss’ detected was £1193. Overall mortality was no higher and possibly lower than in published studies.
Conclusion: We believe that this model of care may be suitable for the management of patients with bacteraemia. A study assessing the cost-effectiveness of this approach is required.
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Introduction |
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Bacteraemia is a major cause of health care expenditure and is associated with higher mortality than non-bacteraemic infections.1–5 There has been increasing concern regarding hospital-acquired bacteraemia, resulting in improvement initiatives to reduce incidence. When bacteraemia does occur, the prompt and appropriate management of patients is likely to be vital in optimizing outcomes. Certain processes, in particular, source control (e.g. drainage of an abscess) and appropriate antibiotics have been associated with improved outcomes.6–11 Ensuring that such processes are systematically achieved is difficult as patients with bacteraemia are usually cared for by a broad range of specialists. Some studies have found associations between achievement of processes or outcomes and consultation by an infection specialist (microbiologist or infectious diseases physician).12–18
Currently in the United Kingdom, most advice regarding the management of patients with bacteraemia is provided by microbiologists, usually by phone to general wards with microbiology wards rounds in key areas, such as the intensive care unit and haematology/oncology wards. It is unusual for a high proportion of patients with bacteraemia to receive a detailed bedside review, including the retaking of the history/examination, by an infection specialist. In response to root-cause analyses, we developed a dedicated bacteraemia service. The objective of this article is to describe the development, implementation and impact of the service, including the characteristics of the patients seen, health outcomes and resource use.
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Methods |
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Development and implementation
Root-cause analyses of cases perceived to be suboptimally managed revealed common themes: breakdown in communication between laboratory and ward; ignorance regarding the importance of bacteraemia; suboptimal antibiotic therapy; and failure to investigate potential sources of bacteraemia. All of our hospitals infection specialists (four microbiologists and three infectious diseases physicians) met to discuss how to improve these processes. It was decided that a dedicated service should be developed to provide a bedside consultation by an infection specialist for all patients with bacteraemia. Because of human resource limitations, it was decided that the service would be limited to all wards on one site and key wards on the second site of our two-site 1500 bed teaching hospital trust during a pilot period with the aspiration of subsequently expanding the service to all wards on both hospital sites. Patients with Gram-negative bacteraemia and a contemporaneous identical urine isolate were not reviewed routinely, although patients with polymicrobial or Gram-positive bacteraemia, or bacteraemia due to unusual or resistant Gram-negative bacteria, secondary to a urinary source were seen. Patients thought to have contaminated cultures were also not seen, but patients with risk factors (e.g. prosthetic heart valve) for significant coagulase-negative staphylococcal bacteraemia were reviewed.
The service began in June 2005. Patients with bacteraemia are initially managed by a microbiologist as before (mostly phone advice). Details of patients thought to have a significant bacteraemia are communicated to the on-call consultant in infectious diseases. Patients are then seen at the bedside by one of the infectious diseases consultants or specialist registrars. The patient's antimicrobial therapy is reviewed and advice provided regarding further investigations, similar to traditional formal consultations. Immediate essential advice is written in the patient's case notes and verbally to the clinical team. A detailed type-written report is then sent to the patient's ward, consultant and the relevant microbiologist within 24 h of the consultation (Figure 1).
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Definitions
Changes in antibiotic therapy were defined as: (i) increased—dose increased or switched from oral to intravenous (IV) therapy or an agent added; (ii) decreased—dose decreased or switched from IV to oral or more than or equal to one antibiotic stopped; (iii) modified—switched to an antibiotic more appropriate for that infection, but not necessarily increased or decreased in intensity; and (iv) unchanged. Concordant antibiotic therapy was defined as an antibiotic regimen that the isolated organism was sensitive to based on standard laboratory antibiotic sensitivity testing. Discordant therapy was defined as a regimen that the isolated organism was resistant to.
Data collection and analyses
A copy of the report was stored and data subsequently entered into an Excel spreadsheet. Additional data were added using the hospital's computer results system. Accuracy of data entry was then checked. Statistical analyses were performed using SPSS (version 10). Data are presented as means and proportions. Means were compared using the Student's t-test. Proportions were compared using the 
2 or Fisher's exact test. A two-sided P-value of 
0.05 was taken to be statistically significant.
Resource use
At the time of dictating the bacteraemia letter, physicians are asked to document the length of the consultation in minutes. An additional 5 min per consultation was added to allow for dictation of the report. The time to type and send a report was estimated by the three infectious diseases’ secretaries. Salaries were taken at the midpoint of employees’ pay scales. The costs of tests and consumables were provided by one of the hospital's senior accountants. Antibiotic costs were provided by one of the hospitals’ senior pharmacists. The costs of developing and delivering the service were added to antibiotic and investigation costs. The total costs were then linked to measured changes in process. Sensitivity analyses were performed around the costs of antibiotics and the assumed mean length of therapy.
Benchmarking of outcomes
We performed a Pubmed and Medline search using the keywords bacteraemia, outcomes, recrudescence, recurrent and mortality to identify published literature to compare our outcomes against. We also searched relevant websites, such as that of the UK's Health Protection Agency, and references of identified papers. The intention was to prioritize recent UK data over that from developing nations or dissimilar healthcare systems.
Qualitative analyses
The type-written reports were read and reread to identify: (i) suboptimal care prior to consultation; and (ii) processes performed by the bacteraemia service team that could be improved and that may not have been detected by the quantitative analyses. Descriptions of identified suboptimal processes were recorded in detail and in a manner that retained meaning in an Excel spreadsheet. When appropriate, text from the type-written reports was recorded verbatim. Identified processes were then organized into themes and sub-themes under the above headings.
The qualitative data were also used to identify potential ‘near-miss’ events. These were defined as: (i) delay in (>24 h) or failure to remove a central venous (CV) line in Staphylococcus aureus bacteraemia; (ii) delay (>24 h) in commencing antibiotics in confirmed bacteraemia; (iii) under-treatment (<2 weeks course length) of S. aureus bacteraemia; (iv) antibiotic therapy not covering the isolated organism; (v) under-treatment (low dose) of endocarditis or other ‘deep-seated’ infection; (vi) under-treatment (low dose) of candidaemia.
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Results |
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Descriptive statistics
One hundred and fifty-one patients were seen between 1 June 2005 and 1 November 2006. Fifty-five percent of patients (83/151) were seen by a consultant and 45% (68/151) by a specialist registrar. The characteristics of these patients are shown in Table 1. The organisms isolated and the likely sources of infection are shown in Table 2.
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Processes of care before and after consultation
Changes in processes of care as a result of the consultation are shown in Table 3. Changes in the antibiotic regimen occurred in 93 patients (62%) (Table 4). Consultations resulted in a reduced proportion of patients being exposed to a broad-spectrum antibiotic (defined as cephalosporins, co-amoxiclav or piperacillin/tazobactam); 41/151 (27%) vs. 24/151 (16%) (
2-test = 5.67, P = 0.01) with exposure to intermediate-spectrum (58/151 [38%] before, 68/151 [45%] after) and narrow-spectrum (81/151 [54%] before, 87/151 [58%] after) antibiotics increasing. Transfer to the infectious diseases unit was organized in 18 cases (12%), with follow-up for a further 26 patients (17%).
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Outcomes
Outcomes are shown in Table 3. Of the patients who had S. aureus bacteraemia, 30-day mortality was 24%, 14% (6/42) in methicillin-sensitive (MSSA) and 37% (12/32) in methicillin-resistant (MRSA) isolates (
2 = 5.32, P = 0.02). Recrudescence at 90 days was also higher in MRSA (14%) than in MSSA (6%) bacteraemia patients, but this difference was not statistically significant (Fisher's exact test, P = 0.3). Recrudescence at 90-days in MRSA (4/16, 25%), however, was statistically higher compared to all other isolates (5/79, 6%, Fisher's exact test P = 0.04).
Resource use
The mean length of consultations was 25 min (range 5–60 min) with a total time of 59 h and 30 min throughout the 18-month study period (39 h 40 min per year). The costs associated with development and delivery of the service are shown in Table 5. The mean daily costs of the antibiotic regimen before and after consultation using the actual costs to the hospital were £10–27 and £14–45 (t-test P = 0.07), respectively, and using British National Formulary (BNF) prices £21–45 and £26–99 (t-test P = 0.06), respectively. Antibiotic costs, cost per change in process and sensitivity analyses are shown in Table 5.
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Benchmarking of outcomes
We identified relatively little data from the United Kingdom. Minton et al. reported a mortality of 27% and 22% (23% overall) before and after an initiative to improve the quality of care for patients with bacteraemia in a similar sized UK teaching hospital.18 This is similar to the mortality reported in a much larger cohort of patients from Denmark (23% vs. 19% in our cohort).19 In S. aureus bacteraemia, a study from Birmingham, UK found an attributable mortality of 16% in MSSA and 33% in MRSA bacteraemia.20 A larger study from Oxford found an overall 30-day mortality of 29%, 27% in MSSA and 34% in MRSA (vs. 24% overall, 14% in MSSA and 37% in MRSA in our cohort).21
Qualitative analyses
Emerging themes and subthemes are shown in Table 6. Strong themes relating to suboptimal care prior to the consultation were: (i) the antibiotic regimen did not cover the isolated organism; (ii) S. aureus bacteraemia being treated with oral antibiotics; (iii) under-treatment of severe/serious infections; and (iv) delay or failure to remove an infected CV line. Strong themes relating to processes performed suboptimally by the bacteraemia service were: (i) lack of advice regarding IV–oral switch and/or length of therapy; (ii) the clarity of the advice provided; and (iii) the rationale for the advice. Two themes, failure to record observations at the time of blood culture and the length of therapy after removal of an infected CV line, were relevant to both the team caring for the patient and the bacteraemia service. Using the ‘near-miss’ definitions (see Methods section), 19 events were identified. Advice provided by the bacteraemia team was deemed to be potentially harmful in seven cases (four seen by consultants): (i) oral ciprofloxacin recommended for a MRSA bacteraemia; (ii) source thought to be ‘contamination’ in patient with dual MSSA/MRSA bacteraemia, fever and a post-operative biliary drain from which MRSA had been isolated; (iii) antibiotics stopped in patient with polymicrobial bacteraemia (Enterococcus spp., Klebsiella spp. and Citrobacter spp.), fever and severe abdominal pain; (iv) two cases of ‘over-dosing’—rifampicin (600 mg/8 h) and teicoplanin (6 mg/kg in severe renal impairment); and (v) two cases of short therapy (one 2 days and another 7 days) in S. aureus bacteraemia; 14 days was taken to be the minimum standard of care in this study. Of the seven patients, one had died by 90 days, but this was unrelated to the error. Of the other patients, patient 3 recrudesced at 48 h and was subsequently shown to have cholecystitis.
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Discussion |
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Ensuring that all patients with bacteraemia are reviewed at the bedside by an infection specialist is one potential model of care for the management of bacteraemia. Our results show that such consultations lead to changes in the antibiotic prescription in nearly two-thirds of patients, and recommendations about further investigations in most patients. Despite a higher pre-consultation level of concordance of the antibiotic regimens compared with that found by Minton et al. (87% vs. 65%),18 62% still required some form of optimization at review; our higher pre-consultation concordance may have been due to an accessible and well recognized trust-wide antibiotic guideline and/or high quality initial microbiology advice. Some patients do not have antibiotic sensitivity data available at the time of consultation, which may explain why 6% of patients were still receiving a regimen that the isolated organism was resistant to after consultation. The service also identified other suboptimal processes of care (see Qualitative analyses results section and Table 6) that could be considered ‘near-miss’ events and may have lead to poorer patient outcomes. These deficiencies were similar to those identified pre-implementation by root-cause analyses (see Methods section) and in other studies.13,15
Because of the potential for differences in case-mix, comparisons of clinical outcomes need to be interpreted with caution. Mortality in this cohort of patients appears to be no worse, however, and possibly better than recently reported UK data. We were unable to link our data to a clinical or patient-based outcome such as mortality or quality of life. Given that there is relatively little high-quality evidence about the link between achievement of processes of care and outcomes in bacteraemia, whether the cost per change in process measure is worthwhile will predominantly depend on the perspective of the provider. Nevertheless, in light of the data presented, positive feedback from consultant colleagues, and the current importance being given to the prevention and management of healthcare associated infections, our hospital is intending to support the service, which has recently expanded to cover all cases of significant bacteraemia on all wards.
The service integrates well with initiatives to prevent and treat healthcare-associated infections, and has contributed to our hospital being on trajectory for key government targets. When alert (restricted) antibiotics (e.g. linezolid) are prescribed, the report is also sent to the hospital's pharmacy. In healthcare-associated bacteraemia, reports are sent to the medical director to inform mandatory root-cause analyses. Similar to previous studies, the results suggest a positive impact on antibiotic stewardship. In contrast to the study by Cunney et al.,13 however, antibiotic costs increased. This is probably because under-treatment (e.g. under-dosing in endocarditis) is commoner than over-treatment in our hospital. Also, some expensive restricted antibiotics, such as linezolid, are only prescribed by infection specialists, which may lead to increased costs. Nathwani et al. found that a similar service was cost-neutral with respect to antibiotic costs.15 Anecdotally, the bedside consultation also facilitates on-the-job training of junior doctors about infection, prevention and management, an area known to be in need of improvement.22
The results also identified areas in which the bacteraemia service needs to improve. Only three-quarters of patients were seen within 2 days of referral from microbiology, the a priori minimum audit standard set at inception. This, in part, may be due to the split site nature of our hospital. Other suboptimal processes (Table 6) have been fed-back and will form audit standards in the future. There was considerable variation (from 2 days to 6 weeks) in the planned length of therapy suggested by both non-experts before consultation and infection specialists at consultation following removal of infected CV lines. This may reflect important clinical factors in different cases and/or the lack of high-quality evidence in this area. As CV lines were the commonest source of bacteraemia, this should be a key target for future research.
Limitations
As with all observational data, there is the potential for bias and confounding. The pilot nature of the service and human resource constraints mean that the data are skewed to certain areas of the hospital, in particular nephrology and other medical sub-specialties. We acknowledge that the lack of a control group hinders the ability to assess clinical outcomes. A number of necessary assumptions were made for the economic analyses. Nevertheless, we believe our data and experience will be useful to other hospitals considering such a service.
In conclusion, bedside consultations in patients with bacteraemia resulted in changes to the antibiotic prescription in over 60% of cases and detected considerable suboptimal processes of care. Policy makers or hospital managers may be unconvinced by descriptive studies, but this or similar models are likely to represent the future of infection practice in the United Kingdom; a move away from the traditional, but under-utilized formal consultation approach to roving teams of infection experts providing unsolicited consultations for all hospitalized patients with infection. As demonstrated, this can integrate well with government policy on hospital-acquired infections, but will require a fundamental shift in the way clinical infection services are organized in the United Kingdom. The cost-effectiveness of this approach should be investigated as part of the research for patient benefit agenda.
Conflict of interest: None declared.
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