A.P.R. Wilson

Antibiotic use and impact on outcome from bacteraemic critical illness: the BActeraemia Study in Intensive Care (BASIC)

BACKGROUNDnThe lack of prospective, randomized, controlled trial data to guide optimal antibiotic use in bacteraemic critically ill patients has led to a wide variety of strategies and major issues with drug resistance. We therefore prospectively investigated the epidemiology of bacteraemia and fungaemia in intensive care units (ICUs); and the impact of timing, type and appropriateness of antibiotic intervention.nnnMETHODSnWe conducted a multinational, multicentre, prospective observational study in 132 ICUs from 26 countries with no interventions.nnnRESULTSn1702 patients [European (69.6%), Australasian (12.2%), South American (8.3%) and Asian (9.9%)] developed 1942 bacteraemic episodes over the study period. Mortality rates were similar for those receiving empirical (40.5%), semi-targeted (37.6%) or fully targeted (33.3%) antibiotic therapy (P=0.40), and in those initially receiving broad- (39.3%) or restricted-spectrum (39.1%) therapy (P=0.94). First-line therapy was effective in terms of the antibiogram (where available) in 70.4% of cases. This in vitro susceptibility ranged from 76.3% for broad-spectrum antibiotics to 46.3% for restricted-spectrum antibiotics (P<0.0001). However, no antibiotic policy-associated variable, including in vitro susceptibility (odds ratio 0.89, 95% confidence interval 0.61-1.30), was a statistically significant predictor of mortality.nnnCONCLUSIONSnWe could not show an impact of antibiotics on mortality in critically ill patients, despite in vitro activity and early commencement. Randomized, multicentre trials are urgently needed to establish the appropriate duration, timing and combinations of antibiotics that will both optimally treat infection and minimize development of resistance and other complications.

Quantitative microbiology in the management of burn patients. II. Relationship between bacterial counts obtained by burn wound biopsy culture and surface alginate swab culture, with clinical outcome following burn surgery and change of dressings

The use of quantitative bacteriology in the burns unit has been thought to be efficient in predicting sepsis or graft loss. To examine the relationship between clinical outcome and bacterial densities on and in the burn wound, 69 biopsy/surface swab pairs were collected from 47 patients on 64 occasions, either immediately prior to excision and grafting, or at routine change of dressings. The mean per cent TBSA burn was 16 (range 1-65). There was a significant correlation between log total bacterial count by biopsy with total white cell count and age (P = 0.028), and a significant negative correlation between total bacterial count by swab with per cent TBSA (P = 0.006). There was no significant difference in bacterial counts between patients judged to be a clinical success or clinical failure (72 h follow-up), either after undergoing excision and grafting, or change of dressings, and no difference in counts between patients with perioperative bacteraemia and those without. With burns > 15 per cent TBSA, a relationship between bacterial counts and subsequent sepsis or graft loss still was not demonstrated. It is suggested that quantitative bacteriology by burn wound biopsy or surface swab does not aid the prediction of sepsis or graft loss.

Hand hygiene after touching a patient's surroundings: the opportunities most commonly missed

BACKGROUNDnHealthcare workers generally underestimate the role of environmental surfaces in the transmission of infection, and compliance with hand hygiene following contact with the environment is generally lower than following direct patient contact. To reduce the risk of onward transmission, healthcare workers must identify the need to wash hands with specific tasks or events.nnnAIMnTo observe the movement of staff in critical care and general wards and determine the routes most commonly travelled and the surfaces most frequently touched with and without appropriate hand hygiene.nnnMETHODSnFifty-eight 90xa0min sessions of unobtrusive observation were made in open bays and isolation rooms. Link analysis was used to record staff movement from one location to another as well as the frequency of motion. Hand-hygiene audits were conducted using the World Health Organization five moments for hand hygiene observational tool.nnnFINDINGSnIn critical care, the majority of movement occurred within the bed space. The bedside computer and equipment trolley were the surfaces most commonly touched, often immediately after patient contact. In the general ward, movement between bed spaces was more common and observed hand hygiene ranged from 25% to 33%. Regardless of ward type, observed hand-hygiene compliance when touching the patient immediately on entering an isolation room was less than 30%.nnnCONCLUSIONSnHealthcare workers must be made aware that bacterial spread can occur even during activities of perceived low risk. Education and intervention programmes should focus on the potential contamination of ward computers, case notes and door handles.

Efficacy of two hydrogen peroxide vapour aerial decontamination systems for enhanced disinfection of meticillin-resistant Staphylococcus aureus, Klebsiella pneumoniae and Clostridium difficile in single isolation rooms

BACKGROUNDnHydrogen peroxide vapour (HPV) disinfection systems are being used to reduce patients exposure to hospital pathogens in the environment. HPV whole-room aerial disinfection systems may vary in terms of operating concentration and mode of delivery.nnnAIMnTo assess the efficacy of two HPV systems (HPS1 and HPS2) for whole-room aerial disinfection of single isolation rooms (SIRs).nnnMETHODSnTen SIRs were selected for manual terminal disinfection after patient discharge. Test coupons seeded with biological indicator (BI) organisms [∼10(6) colony-forming units (cfu) of meticillin-resistant Staphylococcus aureus (MRSA) or Klebsiella pneumoniae, or ∼10(5)cfu Clostridium difficile 027 spores] prepared in a soil challenge were placed at five locations per room. For each cycle, 22 high-frequency-touch surfaces in SIRs were sampled with contact plates (∼25cm(2)) before and after HPV decontamination, and BIs were assayed for the persistence of pathogens.nnnFINDINGSnApproximately 95% of 214 sites were contaminated with bacteria after manual terminal disinfection, with high numbers present on the SIR floor (238.0-352.5cfu), bed control panel (24.0-33.5cfu), and nurse call button (21.5-7.0cfu). Enhanced disinfection using HPV reduced surface contamination to low levels: HPS1 [0.25cfu, interquartile range (IQR) 0-1.13] and HPS2 (0.5cfu, IQR 0-2.0). Both systems demonstrated similar turnaround times (∼2-2.5h), and no differences were observed in the efficacy of the two systems against BIs (C.xa0difficile ∼5.1log10 reduction; MRSA/K.xa0pneumoniae ∼6.3log10 reduction). Despite different operating concentrations of hydrogen peroxide, MRSA persisted on 27% of coupons after HPV decontamination.nnnCONCLUSIONnEnhanced disinfection with HPV reduces surface contamination left by manual terminal cleaning, minimizing the risks of cross-contamination. The starting concentration and mode of delivery of hydrogen peroxide may not improve the efficacy of decontamination in practice, and therefore the choice of HPV system may be based upon other considerations such as cost, convenience and logistics.

Recommendations for surveillance priorities for healthcare-associated infections and criteria for their conduct

Surveillance and feedback of results to clinical teams is central to performance improvement in managing healthcare-acquired infections. A major role of the Advisory Committee on Antimicrobial Resistance and Healthcare-Associated Infections (ARHAI) is to advise on surveillance priorities. A sub-committee was set up to systematically review existing UK surveillance schemes. The following three systems were examined in detail: mandatory reporting of methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia and Clostridium difficile infection to the HPA; surveillance of surgical site infection undertaken by the HPA; and surgical site infection surveillance undertaken at University College London Hospital. Recommendations included the extension of mandatory reporting to include bacteraemia due to Escherichia coli and methicillin-susceptible S. aureus (MSSA), post-discharge surveillance of surgical site infection, the need for validation of surveillance systems and mandatory reporting of Caesarean section wound infections. Mandatory reporting of bacteraemia due to E. coli and MSSA were introduced during 2011 and further extension of surveillance is likely.

A feasibility service evaluation of screening and treatment of group A streptococcal pharyngitis in community pharmacies

Objectives The UK 5 year antimicrobial resistance strategy recognizes the role of point-of-care diagnostics to identify where antimicrobials are required, as well as to assess the appropriateness of the diagnosis and treatment. A sore throat test-and-treat service was introduced in 35 community pharmacies across two localities in England during 2014–15. Methods Trained pharmacy staff assessed patients presenting with a sore throat using the Centor scoring system and patients meeting three or all four of the criteria were offered a throat swab test for Streptococcus pyogenes, Lancefield group A streptococci. Patients with a positive throat swab test were offered antibiotic treatment. Results Following screening by pharmacy staff, 149/367 (40.6%) patients were eligible for throat swab testing. Of these, only 36/149 (24.2%) were positive for group A streptococci. Antibiotics were supplied to 9.8% (nu200a=u200a36/367) of all patients accessing the service. Just under half of patients that were not showing signs of a bacterial infection (60/123, 48.8%) would have gone to their general practitioner if the service had not been available. Conclusions This study has shown that it is feasible to deliver a community-pharmacy-based screening and treatment service using point-of-care testing. This type of service has the potential to support the antimicrobial resistance agenda by reducing unnecessary antibiotic use and inappropriate antibiotic consumption.

Use of gentamicin–collagen sponges in closure of sternal wounds in cardiothoracic surgery to reduce wound infections

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was: Are antibiotic implants like gentamicin-collagen implants useful in preventing sternal wound infections (SWIs)? Altogether, more than 484 papers were found using the reported search; of these, 7 represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. We conclude that most randomized controlled trials (RCTs) have been performed with gentamicin-collagen sponges for sternal closure. Two out of four RCTs showed a significant benefit of the implant in a reduction in superficial and deep SWIs in routine and emergency cardiac surgery. One RCT showed a significant reduction in superficial infections in 2005, a follow-up trial by the same group in 2009 showed a reduction in deep infections as well. Another group has shown a reduction in deep and superficial SWI with gentamicin implant, in an RCT on 800 patients, however have not published details of the complete trial. The third trial on 542 patients showed no benefit of the implant, but was not adequately powered. However, the most recent multicentre RCT conducted on 1052 patients showed no benefit of gentamicin-collagen sponges in elective surgery (coronary artery bypass grafting and/or valve surgery) in high-risk patients with diabetes, obesity or both. Concerns were raised that gentamicin sponges dipped in saline 1-2xa0s prior to application may have lost the gentamicin into the saline, thereby reducing their efficacy and that some surgeons may have been unfamiliar with wound closure with sponges. However, these were robustly refuted by the authors. One RCT showed that gentamicin sponges may cause increased sternal rebleeding if used in double layers. Coagulase-negative staphylococci were predominantly isolated from infected wounds in all the trials except the one from USA, where infections were polymicrobial. Gentamicin resistance among common pathogens causing SWIs can vary from 15 to 80%. Gentamicin-collagen is unlikely to reduce SWIs in high-risk patients and polymicrobial infections.

Whole-genome sequencing in hierarchy with pulsed-field gel electrophoresis: the utility of this approach to establish possible sources of MRSA cross-transmission.

BACKGROUNDnIn order to study the micro-epidemiology of meticillin-resistant Staphylococcus aureus (MRSA) effectively, the molecular typing method used must be able to distinguish between different MRSA strains. Pulsed-field gel electrophoresis (PFGE) can detect small genetic differences but is limited in its potential to distinguish isolates within a major lineage. Whole-genome sequencing (WGS) provides sufficient resolution to support or exclude links between otherwise indistinguishable isolates, but lacks the practical utility of conventional typing methods.nnnAIMnTo explore the utility of WGS in a hierarchical approach with PFGE to help establish possible sources of MRSA cross-transmission in the intensive care setting.nnnMETHODSnPossible transmission routes from donor to recipient via the hands of staff, the air or environmental surfaces were identified. Focused molecular typing used PFGE to explore these transmission hypotheses. WGS was applied when an acquisition event involved a common PFGE pulsotype.nnnFINDINGSnThirty-eight of the 78 acquisition events could not be explored as clinical isolates were not available. PFGE excluded all potential donors from 26 of the remaining 40 acquisition events, but did identify a probable source in 14 new colonizations. Within the hypotheses tested, PFGE supported links between patients occupying the same bay, the same bed space, adjacent isolation rooms and different wards. When a patient source was not identified, PFGE implicated the ward environment and the hands of staff. However, WGS disproved three of these transmission pathways.nnnCONCLUSIONnWGS can complement conventional typing methods by confirming or refuting possible MRSA transmission hypotheses. Epidemiological data are crucial in this process.

ESBL-producing Gram-negative organisms in the healthcare environment as a source of genetic material for resistance in human infections

BACKGROUNDnThe increasing prevalence of extended-spectrum β-lactamase (ESBL)-producingxa0Enterobacteriaceae in the healthcare setting and in the community despite established infection control guidelines indicates that these microorganisms may possess survival strategies that allow them to persist in the environment.nnnAIMSnTo determine the extent and variation in endemic ESBL-carrying species in different ward environments, and to investigate the potential for cephalosporin resistance to be transferred from environmental isolates to human pathogens.nnnMETHODSnConventional microbiological methods were used to sample 1436 environmental surfaces for ESBL-producing bacteria. Transconjugation assays (broth mating experiments) were performed using environmental ESBL-producing isolates as donors and streptomycin-resistant Escherichia coli (NCTC 50237) as the recipient.nnnFINDINGSnThe prevalence of ESBL-producing bacteria on surfaces in a non-outbreak setting was low (45/1436; 3.1%). The sites most likely to be contaminated were the drains of handwash basins (28/105; 26.7%) and floors (14/160; 8.8%). Fifty-nine ESBL-carrying organisms were isolated. Of these, Klebsiella spp. (33.9%), Enterobacter spp. (20.3%), Pantoea spp. (15.3%) and Citrobacter spp. (13.6%) were the most common isolates. ESBL determinants were transferred successfully from three representative environmental isolates (Pantoea calida, Klebsiella oxytoca, Raoultella ornithinolytica) to the human pathogen E.xa0coli.nnnCONCLUSIONnESBL-producing Gram-negative isolates were recovered from the hospital environment in the absence of any ESBL infection on the wards. The drains of handwash basins should be considered potential long-term reservoirs of multi-drug-resistant bacteria and drug resistance genes. These genes can reside in various genera of hardy environmental organisms and be a potential source of ESBL for more common human pathogens.

Ultraviolet-C decontamination of hand-held tablet devices in the healthcare environment using the Codonics D6000™ disinfection system

Mobile phones and tablet computers may be contaminated with micro-organisms and become a potential reservoir for cross-transmission of pathogens between healthcare workers and patients. There is no generally accepted guidance on how to reduce contamination on mobile devices in healthcare settings. Our aim was to determine the efficacy of the Codonics D6000™ UV-C disinfection device. Daily disinfection reduced contamination on screens and on protective cases (test) significantly, but not all cases (control) could be decontaminated. The median aerobic colony count on the control and the test cases was 52xa0cfu/25xa0cm2 (interquartile range: 33-89) and 22xa0cfu/25xa0cm2 (10.5-41), respectively, before disinfection.