Survivorship and Patient-Reported Outcomes of an Uncemented Vitamin E-Infused Monoblock Acetabular Cup: A Multicenter Prospective Cohort Study.

BACKGROUND: Addition of vitamin E to polyethylene is theorized to reduce the potential for oxidative wear in acetabular components. This paper presents a multicenter prospective cohort study that reports on outcomes from use of a Vitamin E-infused highly cross-linked polyethylene acetabular cup. METHODS: Patients were recruited across nine medical institutions. Clinical outcome measures recorded were the Harris Hip Score, visual analogue score for pain and satisfaction. Evidence of implant loosening or osteolysis was collected radiologically. Cup survival and reasons for revision in relevant cases were also recorded. Data collection was undertaken preoperatively, at 6-12 weeks, 6 months, 1 year, 2 years, and 5 years. A total of 675 patients were recruited, with 450 cases available at final review. Data regarding cup survival was available to 8 years and 9 months postoperatively. RESULTS: Improvements in both the Harris Hip Score and visual analogue score for pain and satisfaction were recorded at all time points, with these being maintained through the length of follow-up. In total, 89% of cups were implanted within the Lewinnek safe zone. A lucent line was identified in one case, with no evidence of acetabular osteolysis observed throughout the follow-up period. Cup survival was 98.9% at 8 years and 9 months. No revisions for aseptic loosening were observed. CONCLUSIONS: The use of a vitamin E-infused polyethylene acetabular cup demonstrates reassuring patient-reported outcomes, radiological measures, and cup survival at medium to long-term follow-up.

Estimating the effectiveness of isolation and decolonization measures in reducing transmission of methicillin-resistant Staphylococcus aureus in hospital general wards.

Infection control for hospital pathogens such as methicillin-resistant Staphylococcus aureus (MRSA) often takes the form of a package of interventions, including the use of patient isolation and decolonization treatment. Such interventions, though widely used, have generated controversy because of their significant resource implications and the lack of robust evidence with regard to their effectiveness at reducing transmission. The aim of this study was to estimate the effectiveness of isolation and decolonization measures in reducing MRSA transmission in hospital general wards. Prospectively collected MRSA surveillance data from 10 general wards at Guy's and St. Thomas' hospitals, London, United Kingdom, in 2006-2007 were used, comprising 14,035 patient episodes. Data were analyzed with a Markov chain Monte Carlo algorithm to model transmission dynamics. The combined effect of isolation and decolonization was estimated to reduce transmission by 64% (95% confidence interval: 37, 79). Undetected MRSA-positive patients were estimated to be the source of 75% (95% confidence interval: 67, 86) of total transmission events. Isolation measures combined with decolonization treatment were strongly associated with a reduction in MRSA transmission in hospital general wards. These findings provide support for active methods of MRSA control, but further research is needed to determine the relative importance of isolation and decolonization in preventing transmission.

An association between bacterial genotype combined with a high-vancomycin minimum inhibitory concentration and risk of endocarditis in methicillin-resistant Staphylococcus aureus bloodstream infection.

INTRODUCTION: Antimicrobial resistance and bacterial virulence factors may increase the risk of hematogenous complications during methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infection (BSI). This study reports on the impact of increasing vancomycin minimum inhibitory concentrations (V-MICs) and MRSA clone type on risk of hematogenous complications from MRSA BSI during implementation of an effective MRSA control program. METHODS: In sum, spa typing, staphylococcal cassette chromosome mec allotyping, and vancomycin and teicoplanin MICs were performed on 821 consecutive MRSA bloodstream isolates from 1999 to 2009. Prospectively collected data, including focus of infection, were available for 695 clinically significant cases. Logistic and multinomial logistic regression was used to determine the association between clone type, vancomycin MIC (V-MIC), and focus of infection. RESULTS: MRSA BSIs decreased by ∼90% during the 11 years. Typing placed isolates into 3 clonal complex (CC) groups that had different population median V-MICs (CC30, 0.5 µg/mL [n = 349]; CC22, 0.75 µg/mL [n = 272]; non-CC22/30, 1.5 µg/mL [n = 199]). There was a progressive increase in the proportion of isolates with a V-MIC above baseline median in each clonal group and a disproportionate fall in the clone group with lowest median V-MIC (CC30). In contrast, there were no increases in teicoplanin MICs. High V-MIC CC22 isolates (1.5-2 µg/mL) were strongly associated with endocarditis (odds ratio, 12; 95% confidence interval, 3.72-38.9) and with a septic metastasis after catheter-related BSI (odds ratio, 106; 95% confidence interval, 12.6-883) compared with other clone type/V-MIC combinations. CONCLUSIONS: An interaction between clone type and V-MIC can influence the risk of endocarditis associated with MRSA BSI, implying involvement of both therapeutic and host-pathogen factors.

Post-operative wound infection in salvage laryngectomy: does antibiotic prophylaxis have an impact?

Salvage laryngectomy carries a high risk of post-operative infection with reported rates of 40-61%. The purpose of this study was to analyse infections in our own patients and review the potential impact of our current antibiotic prophylaxis (AP). A retrospective analysis of infection in 26 consecutive patients between 2000 and 2010 undergoing salvage total laryngectomy (SL) following recurrent laryngeal cancer after failed radiotherapy or chemo-radiation was undertaken. The antibiotic prophylaxis was intravenous teicoplanin, cefuroxime and metronidazole at induction and for the following 24 h. Infection was defined by Tabet and Johnson's grade 5, categorized as pharyngocutaneous fistula. Fifteen patients (58%) developed a post-operative wound infection, which occurred on average at 12 days after surgery. Univariate analysis demonstrated three risk variables that had a significant correlation with infection: alcohol consumption (p = 0.01), cN stage of tumour (p < 0.01), and pre-operative albumin levels <3.2 g/L (p = 0.012). There was a trend, though not significant, for increased infection in patients with high or low BMIs. The most common organisms isolated from clinical samples from infected patients were methicillin-resistant Staphylococcus aureus MRSA (43%), Pseudomonas aeruginosa (36%), Serratia marcescens, Proteus mirabilis and Enterococcus faecalis (7% each). All these organisms are typical hospital-acquired pathogens. Pseudomonas and Serratia were not covered by the prophylactic regime we used. The current antibiotic regime following SL is inadequate as the rate of infection is high. It would therefore seem logical to trial a separate antibiotic protocol of AP for patients undergoing SL that would include an extended course of antibiotics after the standard prophylaxis. In addition, infection rates may also be reduced by improving the metabolic state of patients pre-operatively by multi-disciplinary action. Steps should also be taken to reduce cross-infection with nosocomial pathogens in these patients. Other aspects of surgical management should be also taken in consideration.

Wear and migration are not influenced by head size in a vitamin E-infused highly cross-linked polyethylene acetabular cup.

BACKGROUND: Aseptic loosening and periprosthetic osteolysis are frequent complications in total hip arthroplasty requiring revision surgery. Highly cross-linked polyethylene (HXLPE) implants have improved wear resistance, permitting larger femoral heads. However, such implants may experience surface cracking, mechanical failure, and oxidative damage. Vitamin E-infused HXLPE (VEPE) implants were therefore developed to reduce oxidation without compromising mechanical strength. We addressed the following questions: (1) Does femoral head size affect the midterm annual polyethylene wear rates of VEPE acetabular cups? (2) Does femoral head size affect the midterm migration rates of VEPE acetabular cups? (3) Are clinical outcomes affected by femoral head size? HYPOTHESIS: Annual wear rate, migration rate, and clinical outcomes of VEPE acetabular cups are independent of femoral head size. PATIENTS AND METHODS: This was a prospective, multicentre, observational study of patients that underwent total hip arthroplasty. Hips were grouped according to the size of femoral head implanted (28 mm, 32 mm, and 36 mm). We determined annual wear rate and migration rate of VEPE acetabular cups using the Einzel-Bild-Röntgen-Analyse software. Clinically, we assessed the Harris Hip Score and visual analog score for pain and satisfaction. RESULTS: We followed 253 patients (267 hips) for a mean of 55.0±20.6 months in the 28 mm, 46.2±21.4 months in the 32 mm, and 43.8±22.6 months in the 36 mm group. The annual wear rate was 0.025 mm per year from 1 year to the last follow-up and remained similar between the groups (p>0.05). Also, mean two-dimensional migration rates did not exceed 0.05 mm from 2 years to the last follow-up and remained similar between the groups (p=0.355). Finally, clinical outcomes also did not differ between the groups (p>0.05). Two patients required revision surgery. DISCUSSION: Femoral head size did not influence midterm annual wear rate, migration rate, and clinical outcomes of VEPE acetabular cups. Furthermore, wear and cup migration rates were below the reported values leading to osteolysis and aseptic loosening. Nevertheless, studies with extended follow-up periods will be necessary to confirm these results in the long term. LEVEL OF EVIDENCE: IV.

Antimicrobial-resistant pathogens in animals and man: prescribing, practices and policies.

This meeting focused on infections in humans and animals due to methicillin-resistant Staphylococcus aureus (MRSA), extended-spectrum beta-lactamase (ESBL)-producing bacteria and Clostridium difficile, and their corresponding treatments. MRSA is predominantly a human pathogen, and molecular typing has revealed that certain clones have spread widely both between humans and from humans to animals. ESBL-producing bacteria, particularly those that express the CTX-M beta-lactamases, have been disseminated worldwide. Whilst such strains are usually isolated from humans, some animal isolates also produce CTX-M enzymes. In humans, one clone of CTX-M-producing Escherichia coli, sequence type (ST)131, has been particularly successful. C. difficile, often ribotype 027, commonly colonizes the hospital environment and causes serious infections in humans. In animals, ribotype 078 is more often found, and is an important cause of diarrhoea in piglets. There is a concern that the numbers of MRSA or other antimicrobial-resistant bacteria might increase further when human isolates become established in animals, as this can amplify the numbers of such bacteria by dissemination within animal groups with subsequent spread back to humans. Certain antimicrobials have been implicated in the selection of MRSA, ESBL-producing bacteria and predisposition to infection by C. difficile. Guidelines for treatment and prevention of infections by MRSA, ESBL-producing bacteria and C. difficile were discussed and evidence-based policies were recommended for both humans and animals.

Survival of nosocomial bacteria and spores on surfaces and inactivation by hydrogen peroxide vapor.

With inocula of 6 to 7 log(10) CFU, most vegetative bacteria and spores tested survived on surfaces for more than 5 weeks, but all were inactivated within 90 min of exposure to hydrogen peroxide vapor in a 100-m(3) test room even in the presence of 0.3% bovine serum albumin to simulate biological soiling.

Clinical application of real-time PCR to screening critically ill and emergency-care surgical patients for methicillin-resistant Staphylococcus aureus: a quantitative analytical study.

The clinical utility of real-time PCR screening assays for methicillin (methicillin)-resistant Staphylococcus aureus (MRSA) colonization is constrained by the predictive values of their results: as MRSA prevalence falls, the assay's positive predictive value (PPV) drops, and a rising proportion of positive PCR assays will not be confirmed by culture. We provide a quantitative analysis of universal PCR screening of critical care and emergency surgical patients using the BD GeneOhm MRSA PCR system, involving 3,294 assays over six months. A total of 248 PCR assays (7.7%) were positive; however, 88 failed to be confirmed by culture, giving a PPV of 65%. Multivariate analysis was performed to compare PCR-positive culture-positive (P+C+) and PCR-positive culture-negative (P+C-) assays. P+C- results were positively associated with a history of methicillin-sensitive Staphylococcus aureus infection or colonization (odds ratio [OR], 3.15; 95% confidence interval [CI], 1.32 to 7.54) and high PCR thresholds of signal intensity, indicative of a low concentration of target DNA (OR, 1.19 per cycle; 95% CI, 1.11 to 1.26). P+C- results were negatively associated with a history of MRSA infection or colonization (OR, 0.19; 95% CI, 0.09 to 0.42) and male sex (OR, 0.40; 95% CI, 0.20 to 0.81). P+C+ patients were significantly more likely to have subsequent positive MRSA culture assays and microbiological evidence of clinical MRSA infection. The risk of subsequent MRSA infection in P+C- patients was not significantly different from that in case-matched PCR-negative controls. We conclude that, given the low PPV and poor correlation between a PCR-positive assay and the clinical outcome, it would be prudent to await culture confirmation before altering infection control measures on the basis of a positive PCR result.

Evidence-based prescription of antibiotics in urology: a 5-year review of microbiology.

OBJECTIVE: To analyse the results of positive urine cultures over a 5-year period in a large hospital and urology department (amongst both inpatients and outpatients), assess the prevalence of different organisms and the resistance profiles of a range of antibiotics, and thus provide information on which organisms are likely to cause urosepsis. METHODS: The use of antibiotics should be based on knowledge of which pathogens are present and what resistance patterns are emerging, particularly relevant in surgical disciplines like urology, as antibiotics are now routinely administered peri-operatively, whereby evidence-based prescription is preferable to generic guidelines. We therefore examined almost 25,000 positive urine cultures in our hospital over a 5-year period, and focused on the infections encountered amongst urology patients during this time. RESULTS: A significant proportion of inpatient urinary infection (40%) is caused by Gram-positive bacteria such as Streptococcus faecalis, underlining the need for including Gram-positive cover during urological prophylaxis. The commonest pathogen remains Escherichia coli among both inpatients and outpatients. The ineffectiveness of common antibiotics such as ciprofloxacin and trimethoprim was identified, as was the increase in gentamicin resistance. CONCLUSION: We propose using an aminoglycoside with a penicillin for high-risk cases (e.g. endoscopic stone surgery) while low-risk cases (e.g. flexible cystoscopy with no risk factors) might be managed without such prophylaxis. Pathogenic patterns and resistance rates should be monitored regularly.

Guidelines for UK practice for the diagnosis and management of methicillin-resistant Staphylococcus aureus (MRSA) infections presenting in the community.

These guidelines have been developed by a Working Party convened on behalf of the British Society for Antimicrobial Chemotherapy. Their aim is to provide general practitioners and other community- and hospital-based healthcare professionals with pragmatic advice about when to suspect MRSA infection in the community, when and what cultures should be performed and what should be the management options, including the need for hospitalization.

Validation of the IDI-MRSA system for use on pooled nose, axilla, and groin swabs and single swabs from other screening sites.

A commercial rapid polymerase chain reaction methicillin-resistant Staphylococcus aureus (MRSA) screening method (IDI-MRSA) is validated for the use with nasal swabs transported in liquid Stuart's medium. We investigated the use of IDI-MRSA for screening for MRSA in pooled nose, axilla, and groin swabs and in single swabs from skin puncture sites, wounds, throat, rectum, and groin using swabs transported in Amies medium without charcoal. We performed the IDI-MRSA test on swabs that had been used for routine MRSA broth culture and which were selected to be about 50% MRSA positive. We compared the IDI-MRSA result with the MRSA culture result. With 201 pooled sets, the sensitivity of IDI-MRSA was 85% and the specificity 95%. With 32 single screening swabs, sensitivity was 94% and specificity 80%. The method is not compromised by swab transport in Amies medium if an additional heating step is used. We had a low rate of initial inhibition (1.3%), which may have been due to the extra heating step used to liquefy gel from the Amies medium. Thus, in this study IDI-MRSA gives similar results to culture with pooled or single swabs from multiple screening sites.

The use of prophylactic antibiotics in head and neck oncological surgery.

PURPOSE OF REVIEW: An overview of best evidence-based current practice in the use of prophylactic antibiotics in elective oncological head and neck surgery is presented. RECENT FINDINGS: Patients undergoing head and neck oncological surgery are at great risk of developing complications following surgery. The incidence of wound infection has been reported to be as high as 87%, often with devastating effects. Prophylactic antibiotics have helped to reduce significantly the risk of infection; however, clinicians managing these patients should also have a thorough understanding of the risk factors leading to postoperative infections and should apply the most basic surgical principles at all times, to minimize infection rates. SUMMARY: Prophylactic antibiotics usage in clean-contaminated major oncological head and neck surgery is mandatory to reduce the risk of infection. In clean major oncological head and neck surgery their use is also advisable but there is no evidence that in clean surgery for benign disease it offers any advantage. Short antibiotic regimes of four doses per 24 h are as effective as prolonged courses regardless of the complexity of the procedure. A combination of antibiotic agents covering aerobic, anaerobic and Gram-negative bacteria is superior to single agents. High-risk patients should be also given short regimes, as there is no evidence that prolonged courses are of more benefit in these patients. Methicillin-resistant Staphylococcus aureus infection can have devastating consequences for patients undergoing major head and neck surgery. Protocols of prevention and treatment should be in place in all institutions treating patients with head and neck cancer. Close collaboration between surgical, microbiology and infection-control teams is essential.

Point-of-Care Testing for Clostridium Difficile Infection: A Real-World Feasibility Study of a Rapid Molecular Test in Two Hospital Settings.

INTRODUCTION: In the developed world, Clostridium difficile infection (CDI) is the most important cause of nosocomial infectious diarrhea. In addition to providing epidemiological data and helping to indicate that a local outbreak may be occurring, laboratory tests are used to augment clinical decisions on individual patients. Very rarely do diagnostic tests provide results at the point of decision making; in the intervening period between requesting investigations on a patient with suspected CDI and return of the laboratory result, decisions must be made regarding patient isolation and treatment. METHODS: A 22-month, real-world feasibility study was conducted in patients with clinically significant diarrhea, in a London Hospital between March 2011 and January 2013, in three older persons' wards and two intensive care units (ICUs) to determine acceptability, ease of use, change in turnaround time and clinical utility of a rapid, polymerase chain reaction (PCR)-based point-of-care test (POCT) (Cepheid GeneXpert(®), Sunnyvale, California, USA) for diagnosis of Clostridium difficile. Nurses in the older persons' ward and laboratory technicians in the ICU were trained to perform the test. Residual samples were sent to the centralized laboratory for parallel testing using a two-step algorithm. RESULTS: A total of 335 samples were tested using the POCT with a median turnaround time of 1.85 h compared with 18 h for the centralized laboratory test. Overall agreement with centralized laboratory testing was 98.1%. Discrepant samples were more frequent on elderly wards than ICU. Overall 20/335 (6%) processing errors were encountered and were highest in the first few months of the study. Significantly more processing errors occurred on the older persons' wards 13/102 (12.7%) than on ICU 7/271 (2.6%). Older persons' patients who had POCT were significantly less likely to have a test requested for bacterial stool culture (3.1% vs. 10.9% p = 0.044). This difference was not observed in the ICU patients. No other differences in ancillary test requesting, mortality or length of stay were observed. CONCLUSIONS: The majority of users reported that the POCT was easy to perform and was an acceptable part of their job. POCT using this system is feasible and acceptable to nursing staff and technicians working within these two hospital-based settings.

Identification and control of a gentamicin resistant, meticillin susceptible Staphylococcus aureus outbreak on a neonatal unit.

We describe the identification and control of an outbreak of gentamicin resistant, meticillin susceptible Staphylococcus aureus (GR-MSSA) on a 36-bed neonatal unit (NNU) in London. Control measures included admission and weekly screening for GR-MSSA, cohorting affected babies, environmental and staff screening, hydrogen peroxide vapour (HPV) for terminal disinfection of cohort rooms, and reinforcement of hand hygiene. Seventeen babies were affected by the outbreak strain over ten months; seven were infected and ten were asymptomatic carriers. The outbreak strain was gentamicin resistant and all isolates were indistinguishable by pulsed-field gel electrophoresis. The outbreak strains spread rapidly and were associated with a high rate of bacteraemia (35% of 17 affected patients had bacteraemia vs. 10% of 284 patients with MSSA prior to the outbreak, p=0.007). None of 113 staff members tested were colonised with GR-MSSA. GR-MSSA was recovered from 11.5% of 87 environmental surfaces in cohort rooms, 7.1% of 28 communal surfaces and 4.1% of 74 surfaces after conventional terminal disinfection. None of 64 surfaces sampled after HPV decontamination yielded GR-MSSA. Recovery of GR-MSSA from two high level sites suggested that the organism could have been transmitted via air. Occasional breakdown in hand hygiene compliance and contaminated environmental surfaces probably contributed to transmission.

Evidence that contaminated surfaces contribute to the transmission of hospital pathogens and an overview of strategies to address contaminated surfaces in hospital settings.

Evidence that contaminated surfaces contribute to the transmission of hospital pathogens comes from studies modeling transmission routes, microbiologic studies, observational epidemiologic studies, intervention studies, and outbreak reports. This review presents evidence that contaminated surfaces contribute to transmission and discusses the various strategies currently available to address environmental contamination in hospitals.

The role of surface disinfection in infection prevention.

BACKGROUND: The Rudolf Schuelke Foundation addresses topics related to hygiene, infection prevention and public health. In this context a panel of scientists from various European countries discussed "The Role of Surface Disinfection in Infection Prevention". The most important findings and conclusions of this meeting are summarised in the present consensus paper. AIM: Although the relevance of surface disinfection is increasingly being accepted, there are still a number of issues which remain controversial. In particular, the following topics were addressed: Transferral of microbes from surface to patients as a cause of infection, requirements for surface disinfectants, biocidal resistance and toxicity, future challenges. METHODS AND FINDINGS: After discussion and review of current scientific literature the authors agreed that contaminated surfaces contribute to the transmission of pathogens and may thus pose an infection hazard. Targeted surface disinfection based on a risk profile is seen as an indispensable constituent in a multibarrier approach of universal infection control precautions. Resistance and cross-resistance depend on the disinfectant agent as well as on the microbial species. Prudent implementation of surface disinfection regimens tested to be effective can prevent or minimize adverse effects. CONCLUSIONS: Disinfection must be viewed as a holistic process. There is a need for defining standard principles for cleaning and disinfection, for ensuring compliance with these principles by measures such as written standard operating procedures, adequate training and suitable audit systems. Also, test procedures must be set up in order to demonstrate the efficacy of disinfectants including new application methods such as pre-soaked wipes for surface disinfection.

Refer prior to biopsy of suspected appendicular soft tissue sarcoma.

AIM: Appendicular soft tissue tumours are rare and inappropriate investigation can result in unnecessary loss of limb or life. We reviewed the investigation and referrals of patients to our institution. METHOD: This is a review of prospectively collected data stored in a tumour registry database. We included all patients (126) referred to the service for investigation and management with a primary soft tissue tumour in 2006 and 2007. RESULTS: There was a highly significant association (RR=6.2) between pre referral procedures (PRPs) and suffering a complication (P<0.0001) in comparison to non-biopsied referrals (NBRs). Those referred by general surgeons were more likely (RR=2.6) to have undergone PRP (p<0.0017). The median interval between referral and senior author review was 8 days for the PRP group and 10 days for the NBR group (P=0.2574). CONCLUSION: Biopsy of suspected appendicular soft tissue sarcoma should be performed by a tumour specialist or in prior consultation with, to minimise adverse outcomes. There was minimal delay till review by an orthopaedic tumour specialist at Middlemore Hospital and achieving a tissue diagnosis does not expedite this.

Rapid detection of sequence variation in Clostridium difficile genes using LATE-PCR with multiple mismatch-tolerant hybridization probes.

A novel molecular assay for Clostridium difficile was developed using Linear-After-The-Exponential polymerase chain reaction (LATE-PCR). Single-stranded DNA products generated by LATE-PCR were detected and distinguished by hybridization to fluorescent mismatch-tolerant probes, as the temperature was lowered after amplification in 5(°)C intervals between 65°C and 25°C. Single-tube multiplex reactions for tcdA, tcdB, tcdC, and cdtB (binary toxin) sequences were initially optimized using synthetic targets and were subsequently done using genomic DNA; each target was detected and characterized by hybridization to one or more probes of a different fluorescent color. In the case of tcdC, three probes, each labeled with a Quasar fluorophore, hybridize to different locations with known mutations, including the deletion at nucleotide 117 in ribotype 027 strains and the premature stop codon mutation at nucleotide 184 in ribotype 078 strains, each of which is associated with hypervirulent infections. These and other tcdC mutations were distinguished from the reference sequence, as well as from each other by changes in the fluorescent contour generated from the combined Quasar-labeled probes. Specific variations in tcdA and tcdB were also identified in the multiplex assay, including those that identified strains lacking toxin A production. This single closed-tube assay generates substantially more information about virulent C. difficile than currently available commercial assays and could be further expanded to provide strain typing.