Improving screening in paediatrics

Birmingham Children’s Hospital NHS Foundation Trust has introduced a new way of detecting MRSA among its most critically ill young patients as part of its ongoing infection prevention and control programme. The Trust has already made significant progress in tackling healthcare-acquired infection, but is striving to improve its record through enhanced surveillance of patients admitted to the intensive care unit (ICU) and other key areas where patients are deemed to be vulnerable. The Healthcare Commission’s Hygiene Code Inspection Report on Birmingham Children’s Hospital NHS Foundation Trust, published in October 2008, observed that rates of MRSA infections have been below the national average for children’s Trusts for “most of the last seven years (and all of the last two), while the infection rate has decreased particularly significantly since 2006.” However, the Trust is taking its infection control and prevention strategy further by expanding its screening programme beyond the requirements outlined by the Government and by implementing more stringent, rapid testing. Despite having comparatively low levels of MRSA, the Trust was concerned that approximately half of MRSA cases were going undetected until the child had actually developed symptoms and fallen ill with the infection. It therefore took the decision to use a polymerase chain reaction (PCR) test, on “high risk” patients, to speed up results and the time taken to respond with appropriate interventions. The project, which initially focused on screening of admissions to the ICU, allows doctors to identify if a patient has MRSA within just one hour by using the GeneXpert test from Cepheid. Traditional culture-based testing, where the bacteria is grown in a petri dish in a microbiology lab, previously took up to three days to verify. Each result obtained using the molecular diagnostic test has been verified as accurate by a further culture test and the hospital has already identified cases of MRSA that they would not normally have picked up on. So far it has proven to be 100% accurate. Dr Jim Gray, consultant microbiologist at Birmingham Children’s Hospital commented: “It is a generally accepted belief in the medical profession that children are not really carriers of the MRSA bacterium. However, we are increasingly finding that this is not the case. “Obtaining an accurate and rapid result for MRSA is absolutely key at the emergency admission point in hospitals. For example, if a patient is critically ill and needs to be admitted to the ICU without delay, clinicians simply cannot afford to wait two to three days for a culture result to see whether the patient has MRSA. By then the patient will certainly have undergone several medical procedures that carry a risk of introducing MRSA into sites of the body where it can cause serious harm, such as the lungs and the bloodstream. Also, if the child is carrying the infection, by the time the results of MRSA cultures arrive back from the lab it may have spread to other children on the unit. “It made sense to start the screening with ICU patients as they are the most susceptible to contracting the MRSA infection due to the bacteria most commonly gaining access to the body through open wounds, injections, catheters and IV sites. It is vital to prevent MRSA from entering the ICU as it is extremely serious and potentially fatal for children who are already critically ill.” One of the advantages of the type of molecular testing being used is the fact that specimens do not have to be processed in batches, which are normally only performed once a day. Testing can be performed in a variety of locations by non-laboratory personnel, which opens up the possibility of providing screening on a 24/7 basis by staff who do not have expert diagnostic skills. It can be performed in non-standard locations in satellite laboratories, emergency department laboratories, or even in the patient admissions area. “In shared room settings, any delays in identifying carriers can cause anxiety for other patients and their carers who have been in close proximity to carriers,” said Dr David Persing, executive vice president and chief medical and technology officer of Cepheid: “They may witness patients who have tested positive being moved into isolation or may find they are moved themselves – in which case, you are presented with the problem of what to tell them. It also creates bed management challenges – faster turnaround times for results enable hospitals to make better decisions at the outset, thus avoiding the ‘bed shuffle’ two or three days after admission.”
Targeted screening Although Birmingham Children’s Hospital has highlighted screening as having an important contribution to improving patient safety, the national focus has been on detection in adult populations. The Government has set the agenda for MRSA screening by stipulating that all elective admissions should be screened by March 2009 along with all emergency admissions “as soon as practicably possible”, but there are some exclusions, which includes groups within paediatrics. “Operational guidance was released in July 2008 which, for the first time, gave robust requirements around paediatrics, stating that we should be screening highrisk paediatric admissions, but it was no more specific than that,” Dr Gray commented. “At Birmingham Children’s Hospital, we have always had an interest in MRSA, but the national focus has been very much around bloodstream infections, which are only the tip of the iceberg. To put this into perspective, we typically see around one or two bloodstream infections per year at our hospital, but we probably see around 50 new patients with MRSA at one site or another. “For most of my career, I have kept detailed records of every patient with MRSA. When we looked back over our experience at the children’s hospital, over a period of 10 years, we found that there had been 410 patients with MRSA. Of these, 215 actually presented with infection. The remaining 195 were colonised but not symptomatic when we detected MRSA. This is a relatively small number, representing around 20 infections per year. However, we thought that if we could detect MRSA in patients before they became infected, we could put measures in place to prevent serious outcome.” When the Trust analysed the 215 cases presenting with infections, it found that the majority of cases were admissions to the intensive care, cardiac and surgery units. It therefore decided to target these high-risk patients for screening. Although they only accounted for around 20% of the patient population, this target group represented 80% of all MRSA cases – enabling the Trust to capture the large majority of infections in the most cost effective way. “We haven’t rolled out PCR beyond this targeted group, for the moment at least, because we needed to be sure that it would be cost effective. PCR is being piloted initially in the ICU to establish how common MRSA is in children and how accurate it is for this patient group,” Dr Gray continued.
Accuracy Commenting on the accuracy of the test, Dr Persing added: “The molecular technique is extremely sensitive and a number of users have come to us and said that they have 10% more ‘positives’ with this system. At first they queried the results, but when they re-analysed these cases and performed additional manipulations to enhance the sensitivity of the culture-based techniques, they found that in fact these were indeed positive cases. Molecular testing can apparently identify cases that would normally be missed, by usual surveillance techniques.” Dr Gray confirmed that the hospital had found a very good correlation between PCR and culture results, and concluded that the test had proven “very accurate”. Some of the Trust’s initial findings have now been revised, however, as increased data has been gathered. He observed: “In terms of prevalence of MRSA, when we started using PCR, it appeared that one in every 10 patients were testing positive. Following further testing of a greater number of patients (around 250-300) we now have more comprehensive statistical data and have found, in fact, that there is a prevalence of around 2-3% – reaffirming the belief that MRSA is much more prevalent in adults,” he commented. Dr Gray believes that the surveillance work the hospital is carrying out on MRSA is very important in building a better picture of the levels of MRSA colonisation within children: “We are learning a lot and asking ourselves many questions. For example, because of the nature of their condition, some of our haematology patients may be admitted as often as three or four times per month. Is it necessary and helpful to screen them every time they come back? “Hopefully the answers that we obtain will assist other UK health Trusts in developing a best practice policy regarding MRSA in child patients. As there is very little research being carried out on MRSA in paediatrics, we are learning as we go along.”
Response to screening Dr Gray observed that the screening programme has been well received by both staff and parents: “We have had a long standing interest in controlling MRSA and have historically performed some screening, so staff were generally comfortable with the implementation of the programme. When you start a screening programme, it is very important that staff understand why you are doing it and that tests are carried out within the desired timescale. It is important when setting up a system that everyone understands how it works and why it has been set up in a specific way. Moreover it needs to be monitored for compliance. “Other considerations include the need for a robust system for transmitting results and ensuring they are acted on. At Birmingham Children’s Hospital, once a positive results is obtained, an infection control nurse is notified, who will make sure the patient immediately receives the treatment required. We were concerned about how patients and their families would react to the screening programme, but there has been so much publicity surrounding the issues, that it has caused a lot less anxiety than we thought it would.” While surveys in adult hospitals show that MRSA is key concern for patients, it does not appear to raise the same level of concern in parents of children coming into hospital, he observed: “Not many people phone before their child is admitted and ask about the issue, and we considered whether screening might heighten anxiety around MRSA. However, we did not find this to be the case. We have a leaflet for those who want more information on the screening programme, but parents are not presenting with questions or concerns on the issue,” he commented. He added that as a relatively new children’s facility, the hospital is in a fortunate position of having ample isolation rooms, although the management of this requires a flexible approach. “While you may be isolating the patient, the parents are spending most of the day with the child and mixing with other parents at the hospital. You cannot stop that from happening. Although there is a theoretical risk of cross-infection, it has not proved to be a significant problem as we speak to parents about the risks and ask them to observe hand hygiene protocols. Children are either in hospital for a short time or are very ill, so isolation does not tend to be a problem from a psycho-social perspective. However, it is important to tailor the approach according to the individual.” The Trust now plans to expand the screening programme to include all elective surgical patients who require overnight admission, along with elective and emergency admissions to the liver and renal units, haematology and oncology wards.