CATALYST: challenging antibiotic allergy status.

OBJECTIVES: To develop a transferable process, CATALYST (challenging antibiotic allergystatus), to assess and challenge penicillin allergy status of inpatients within an NHS Foundation Hospital. METHODS: A multidisciplinary team (MDT) steering group reviewed existing literature and protocols enabling penicillin allergy assessment, challenge and de-labelling. Using this, they identified five key steps forming the basis of CATALYST: clinical assessment of the nature of allergy; inclusion/exclusion criteria; consent; direct oral penicillin challenge; and removal of allergy label. A pharmacist-led pilot was conducted to assess the process, during which a continuous PDSA (plan-do-study-act) cycle was observed. This included formally auditing endpoint data such as accuracy of allergy status in medical records post-intervention. RESULTS: CATALYST was successfully developed with key resources produced to support clinicians. It was piloted in 304 patients, with 172 patients excluded and 132 successful allergy challenges. There was one incident of an adverse event (acute kidney injury) in the 132 successful patients, which occurred as a delayed reaction following 22 days of penicillin therapy. Only 64% of permanent records (held by GP) were appropriately updated when audited at the end of the pilot. CONCLUSIONS: CATALYST is a transferable process to facilitate safe assessment, challenge and removal of spurious penicillin allergy labels. Handover between care sectors forms a key element of allergy removal to ensure all records are updated and work is needed to ensure this process is done effectively.

Hip aspiration culture: analysing data from a single operator series investigating periprosthetic joint infection.

Introduction: We undertook this study to know the sensitivity, specificity and post-test probabilities of hip aspiration when diagnosing periprosthetic hip infections. We also examined "dry tap" (injection with saline and aspiration) results and aspiration volumes. Methods: This is a retrospective cohort study of patients aspirated for suspected periprosthetic joint infection between July 2012 and October 2016. All aspirations were carried out by one trained surgical care practitioner (SCP). All aspirations followed an aseptic technique and fluoroscopic guidance. Aspiration was compared to tissue biopsy taken at revision. Aspiration volumes were analysed for comparison. Results: Between January 2012 and September 2016, 461 hip aspirations were performed by our SCP. Of these 125 progressed to revision. We calculated sensitivity 59 % (confidence interval (CI) 35 %-82 %) and specificity 94 % (CI 89 %-98 %). Pre-test probability for our cohort was 0.14. Positive post-test probability was 0.59 and negative post-test probability 0.06. Aspiration volume for infected ( n = 17 ) and non-infected ( n = 108 ) joints was compared and showed no significant difference. Dry taps were experienced five times; in each instance the dry tap agreed with the biopsy result. Conclusions: Our data show that hip aspiration culture is a highly specific investigation for diagnosing infection but that it is not sensitive. Aspiration volume showed no significant difference between infected and non-infected groups. Each time a joint was infiltrated with saline to achieve a result, the result matched tissue sampling.

Antibiotic resistance profiles of deep surgical site infections in hip hemiarthroplasty; comparing low dose single antibiotic versus high dose dual antibiotic impregnated cement.

Objectives: The incidence of fractured neck of femur (FNOF) is increasing yearly. Many of these patients undergo hip hemiarthroplasty. High dose dual-antibiotic cement (HDDAC) has been shown to reduce rates of deep surgical site infection (SSI) when compared to the current standard low dose single-antibiotic cement (LDSAC) in a quasi-randomised controlled trial. Some concerns exist regarding the use of HDDAC and the development of antibiotic resistance. We reviewed cases of infection in LDSAC and HDDAC bone cement with regard to causative organism and resistance profile. Methods: A retrospective analysis was undertaken of all hemiarthroplasties within our trust from April 2008 to December 2014. We identified all patients in this time period who acquired a deep SSI. The infecting organisms and susceptibility patterns were collated for each cement. Results: We identified 1941 hemiarthroplasties. There were 38 deep surgical site infections representing an infection rate of 3.4% in LDSAC patients and 1.2% in HDDAC patients. The majority of infections were polymicrobial. Staphylococcus epidermidis was the most commonly isolated organism. It accounted for a larger proportion of HDDAC than LDSAC infections (p<0.05). Infection with Corynebacterium species and S. aureus, including MRSA, was eradicated completely with the use of HDDAC. There was no significant change in the proportion of Gram negative and Gram positive infections between the two cements. In Gram positive organisms, there was no significant change in resistance to most antibiotics. Although fewer resistant infections overall, there were significant increases in the proportion of resistance to ciprofloxacin and clindamycin with HDDAC. We observed no resistance to daptomycin or linezolid in either cement and levels of resistance remained low to rifampicin and teicoplanin. In Gram negative organisms, no significant change in resistance was observed. Conclusions: We observed a significantly lower infection rate with the use of HDDAC compared to LDSAC. Such was this reduced infection rate that there was a trend to a lower rate of resistance with the use of HDDAC. However, there were increases in the proportion of resistant cases, most notably to clindamycin and ciprofloxacin in Gram positive organisms, possibly reflecting the higher number of S. epidermidis in the HDDAC group. Whilst the differences in our study were not found to be statistically significant, it is reassuring for teams using HDDAC to prevent SSI in hip hemiarthroplasty.

Impact of universal screening on MRSA bacteremias in a single acute NHS organisation (2006-12): interrupted time-series analysis.

BACKGROUND: In November 2004, a national target was set for the English hospital trusts to reduce the Meticillin-Resistant Staphylococcus aureus (MRSA) bacteremia rate by 60% by April 2008 against the number during 2003/04 (baseline year). In our organisation the number of MRSA bacteremias had risen since 2002 and peaked at 75 in 2005/06. A target was set to reduce the number and series of specific and non- specific interventions was introduced including universal MRSA screening. This study analyzes the impact of universal MRSA screening using a quasi-experimental design using routinely gathered data. METHODS: This study used data gathered routinely for clinical governance, quality control, financial management and outbreak monitoring purposes. Interrupted Time Series (ITS) analysis of 15 pre- and 19 post- universal MRSA screening (and decolonisation) quarterly numbers of bacteremias was carried out where Meticillin-Sensitive Staphylococcus aureus (MSSA) numbers served as non-equivalent dependent variable (control). RESULTS: An immediate sharp fall in MRSA bacteremias was observed following the universal MRSA screening (and decolonisation) commenced in Q2, 2007. The number dropped sharply from 23 (Q2, 2007) to 10 (Q3, 2007) for all MRSA bacteremias, and, from 15 (Q2, 2007) to 6 (Q3, 2007) for bacteremias ≥48 hours of hospitalization. The declining trend continued reaching zero in Q2, 2009 and Q4, 2010 for those with ≥48 hours of hospitalization and all bacteremias, respectively. ITS analysis revealed significant impact of universal MRSA screening on all MRSA bacteremias (ß2 -0.554, p 0.000) and those with ≥48 of hospitalization (ß2 -0.577, p 0.001). Impact estimation predicted 17 and 13 bacteremias for all and those with ≥48 hours hospitalization, respectively in the 19th quarter post-intervention, if the intervention did not occur. The number of MRSA isolates from non-blood culture systemic sources as percentage of admissions also dropped significantly from 3.32% in Q2, 2007 to 1.51% in Q3, 2007 (ß2 -0.506, p 0.000) which is still running low at 0.33% at the end of Q1, 2012. On the other hand, there was no statistically significant impact of universal screening on MSSA bacteremias. CONCLUSIONS: We conclude that of all interventions, the universal MRSA screening (and decolonisation) is the most effective intervention associated with significant and sharp drop in MRSA burden.