Preventing infections caused by carbapenemase-producing bacteria in the intensive care unit - Think about the sink.

OBJECTIVE: Outbreaks caused by carbapenemase-producing bacteria (CPB) are challenging to manage in critical care settings and can be protracted due to inadvertent and ubiquitous ecological niches within the built unit environment, such as handwashing sinks. We discuss evidence from a narrative review on transmission pathways and interventions for critical care practitioners. METHODS: A literature review was undertaken using Pubmed, CINAHL and Embase and included outbreaks of CPB, and equivalent bacteria in critical care units, between 1998 and May 2020. Intervention studies targeting elements of sinks that were employed in response to outbreaks in critical care units were included (n = 30). FINDINGS: We found control measures included sink removal, use of physical barriers or design modification to protect patients from sinks, engineering controls to mitigate bacterial dispersal and administrative controls. A multi-disciplinary approach involving practitioners from critical care, infection prevention and control, engineering and other staff, should be involved in ongoing measures and in outbreak control activities. Ascertaining the optimal method to end CPB outbreaks in critical care is challenging due to the lack of prospective studies available. However, the literature suggests that sinks can and do serve as reservoirs of CPB near critically ill patients, and should be considered hazardous, especially when sub-optimally designed or used.

Assessing the impact of handwashing soaps on the population dynamics of carbapenemase-producing and non-carbapenemase-producing Enterobacterales.

Carbapenemase-producing bacteria have persistent environmental reservoirs in handwashing sinks. This study assessed the impact of handwashing soaps on the population dynamics of carbapenemase-producing Enterobacterales (CPE) and non-CPE. A number of isolates were grown in minimal media with or without two hand soaps marketed for use in health care. Soap A led to increased growth of all isolates except for Escherichia coli. Soap B did not lead to increased growth. The main difference between the formulations was that Soap B contained DMDM hydantoin, a preservative agent and sensitizer. These results show that environmental persistence of CPE may be sustained by common handwashing practices with soap, but further research is required.

'Off the rails': hospital bed rail design, contamination, and the evaluation of their microbial ecology.

Microbial contamination of the near-patient environment is an acknowledged reservoir for nosocomial pathogens. The hospital bed and specifically bed rails have been shown to be frequently and heavily contaminated in observational and interventional studies. Whereas the complexity of bed rail design has evolved over the years, the microbial contamination of these surfaces has been incompletely evaluated. In many published studies, key design variables are not described, compromising the extrapolation of results to other settings. This report reviews the evolving structure of hospital beds and bed rails, the possible impact of different design elements on microbial contamination and their role in pathogen transmission. Our findings support the need for clearly defined standardized assessment protocols to accurately assess bed rail and similar patient zone surface levels of contamination, as part of environmental hygiene investigations.

The Triangular Sign, a Useful Diagnostic Marker for Biliary Atresia: A Case Series of Three Irish Infants

Background The triangular cord (TC) sign is the appearance of a triangular shaped echogenic density visualised immediately cranial to the portal vein bifurcation on ultrasonographic examination. Several studies have reported that this ultrasonographic sign is a reliable and helpful marker in identifying Biliary Atresia (BA). Aims To report the identification of the TC sign in three infants with BA in the Rotunda Hospital, Dublin. Methods A retrospective chart review was performed to evaluate the clinical presentation and imaging of the three patients with positive TC sign and BA. Discussion Timely, accurate diagnosis of BA is essential to minimise morbidity and optimise patient outcome. The TC is a valuable ultrasonographic sign to aid early diagnosis of BA.

Minimizing microbial contamination risk simultaneously from multiple hospital washbasins by automated cleaning and disinfection of U-bends with electrochemically activated solutions.

BACKGROUND: Outbreaks of infection associated with microbial biofilm in hospital hand washbasin U-bends are being reported increasingly. In a previous study, the efficacy of a prototype automated U-bend decontamination method was demonstrated for a single non-hospital pattern washbasin. It used two electrochemically activated solutions (ECA) generated from brine: catholyte with detergent properties and anolyte with disinfectant properties. AIM: To develop and test a large-scale automated ECA treatment system to decontaminate 10 hospital pattern washbasin U-bends simultaneously in a busy hospital clinic. METHODS: A programmable system was developed whereby the washbasin drain outlets, U-bends and proximal wastewater pipework automatically underwent 10-min treatments with catholyte followed by anolyte, three times weekly, over five months. Six untreated washbasins served as controls. Quantitative bacterial counts from U-bends were determined on Columbia blood agar, Reasoner's 2A agar and Pseudomonas aeruginosa selective agar following treatment and 24 h later. FINDINGS: The average bacterial densities in colony-forming units/swab from treated U-bends showed a >3 log reduction compared with controls, and reductions were highly significant (P<0.0001) on all media. There was no significant increase in average bacterial counts from treated U-bends 24 h later on all media (P>0.1). P. aeruginosa was the most prevalent organism recovered throughout the study. Internal examination of untreated U-bends using electron microscopy showed dense biofilm extending to the washbasin drain outlet junction, whereas treated U-bends were free from biofilm. CONCLUSION: Simultaneous automated treatment of multiple hospital washbasin U-bends with ECA consistently minimizes microbial contamination and thus the associated risk of infection.

Elimination of biofilm and microbial contamination reservoirs in hospital washbasin U-bends by automated cleaning and disinfection with electrochemically activated solutions.

BACKGROUND: Washbasin U-bends are reservoirs of microbial contamination in healthcare environments. U-Bends are constantly full of water and harbour microbial biofilm. AIM: To develop an effective automated cleaning and disinfection system for U-bends using two solutions generated by electrochemical activation of brine including the disinfectant anolyte (predominantly hypochlorous acid) and catholyte (predominantly sodium hydroxide) with detergent properties. METHODS: Initially three washbasin U-bends were manually filled with catholyte followed by anolyte for 5min each once weekly for five weeks. A programmable system was then developed with one washbasin that automated this process. This U-bend had three cycles of 5min catholyte followed by 5min anolyte treatment per week for three months. Quantitative bacterial counts from treated and control U-bends were determined on blood agar (CBA), R2A, PAS, and PA agars following automated treatment and on CBA and R2A following manual treatment. FINDINGS: The average bacterial density from untreated U-bends throughout the study was >1×10(5) cfu/swab on all media with Pseudomonas aeruginosa accounting for ∼50% of counts. Manual U-bend electrochemically activated (ECA) solution treatment reduced counts significantly (<100cfu/swab) (P<0.01 for CBA; P<0.005 for R2A). Similarly, counts from the automated ECA-treatment U-bend were significantly reduced with average counts for 35 cycles on CBA, R2A, PAS, and PA of 2.1±4.5 (P<0.0001), 13.1±30.1 (P<0.05), 0.7±2.8 (P<0.001), and 0 (P<0.05) cfu/swab, respectively. P. aeruginosa was eliminated from all treated U-bends. CONCLUSION: Automated ECA treatment of washbasin U-bends consistently minimizes microbial contamination.

Overcoming the problem of residual microbial contamination in dental suction units left by conventional disinfection using novel single component suction handpieces in combination with automated flood disinfection.

OBJECTIVES: Decontaminating dental chair unit (DCU) suction systems in a convenient, safe and effective manner is problematic. This study aimed to identify and quantify the extent of the problems using 25 DCUs, methodically eliminate these problems and develop an efficient approach for reliable, effective, automated disinfection. METHODS: DCU suction system residual contamination by environmental and human-derived bacteria was evaluated by microbiological culture following standard aspiration disinfection with a quaternary ammonium disinfectant or alternatively, a novel flooding approach to disinfection. Disinfection of multicomponent suction handpieces, assembled and disassembled, was also studied. A prototype manual and a novel automated Suction Tube Cleaning System (STCS) were developed and tested, as were novel single component suction handpieces. RESULTS: Standard aspiration disinfection consistently failed to decontaminate DCU suction systems effectively. Semi-confluent bacterial growth (101-500 colony forming units (CFU) per culture plate) was recovered from up to 60% of suction filter housings and from up to 19% of high and 37% of low volume suction hoses. Manual and automated flood disinfection of DCU suction systems reduced this dramatically (ranges for filter cage and high and low volume hoses of 0-22, 0-16 and 0-14CFU/plate, respectively) (P<0.0001). Multicomponent suction handpieces could not be adequately disinfected without prior removal and disassembly. Novel single component handpieces, allowed their effective disinfection in situ using the STCS, which virtually eliminated contamination from the entire suction system. CONCLUSION: Flood disinfection of DCU suction systems and single component handpieces radically improves disinfection efficacy and considerably reduces potential cross-infection and cross-contamination risks. CLINICAL SIGNIFICANCE: DCU suction systems become heavily contaminated during use. Conventional disinfection does not adequately control this. Furthermore, multicomponent suction handpieces cannot be adequately disinfected without disassembly, which is costly in time, staff and resources. The automated STCS DCU suction disinfection system used with single component handpieces provides an effective solution.

Control of bacterial contamination of washbasin taps and output water using Ecasol: a one-year study.

BACKGROUND: Contaminated washbasin taps and output water are an important source of bacteria that may cause nosocomial infection. A five-week pretreatment study of hot and cold water from 15 washbasin taps at Dublin Dental Hospital showed consistently heavy contamination by aerobic heterotrophic bacteria: mean bacterial counts of 482.5 [standard deviation (SD) 293] colony-forming units (cfu)/mL and 5022 (SD 4322) cfu/mL, respectively. AIM: To minimize microbial contamination of washbasin taps and output water in the long term using the electrochemically generated, pH-neutral disinfectant, Ecasol. METHODS: Initially, the 15,000-L water tank providing cold and hot water to washbasins, calorifiers and the distribution network were drained and sediment was removed. The system was shock-dosed with Ecasol 100 ppm to eradicate gross contamination and biofilms. Thereafter, tank water was automatically maintained at Ecasol 2.5 ppm prior to distribution. The microbiological quality of water from five sentinel washbasin taps was monitored weekly for 54 weeks using R2A agar. FINDINGS: The mean counts for hot, cold, mains and tank water during the 54-week study period were 1 (SD 4) cfu/mL, 2 (SD 4) cfu/mL, 205 (SD 160) cfu/mL and 0 cfu/mL, respectively. Swab samples of 33/40 taps, each tested on three separate occasions, yielded no growth on R2A agar, while five samples yielded <20 cfu/swab and two samples yielded >200 cfu/swab. No detrimental effects due to Ecasol were observed in the water network. CONCLUSION: Ecasol consistently minimized bacterial contamination of washbasin taps and output water in a dental hospital setting.

Surgical complications of segmental Le Fort I osteotomy.

Segmental maxillary osteotomy is a useful adjunct in orthognathic surgery for the correction of vertical and transverse maxillary deformities, but we know of few published reports that document complications. We evaluated the complication rates associated with segmental maxillary surgery in our unit by retrospective review of medical records, radiographs, and study models of 85 consecutive patients (mean age 23.3 years, range 14-51; male:female ratio 1:2) treated from 1995 to 2009. Types of deformity were anterior open bite (n=30, 35%), transverse maxillary deficiency (n=24, 28%), anterior open bite with transverse maxillary deficiency (n=28, 33%), and anterior vertical maxillary excess (n=3, 4%). There were 70 tripartite (82%), 13 bipartite (15%), and two quadripartite (2%) maxillas. Twenty-one patients (25%) had bone grafts. Fixation was done using titanium miniplates in 80 patients (94%), and titanium miniplates and resorbable plates in five (6%). The overall complication rate was 27%. Three patients (4%) had devitalisation of teeth, three (4%) developed minor periodontal defects, and one had tooth loss. Eight patients (9%) had plates removed, and two patients developed persistent postoperative palatal fistula. There was no segmental loss of bone or teeth. Our results show that complications in this cohort were relatively low, and that segmental maxillary surgery is safe as an adjunct in carefully selected cases.

Lack of cytotoxicity by Trustwater Ecasol™ used to maintain good quality dental unit waterline output water in keratinocyte monolayer and reconstituted human oral epithelial tissue models.

UNLABELLED: We previously showed that residual treatment of dental chair unit (DCU) supply water using the electrochemically-activated solution Trustwater Ecasol™ (2.5 ppm) provided an effective long-term solution to the problem of dental unit waterline (DUWL) biofilm resulting in DUWL output water quality consistently superior to potable water. OBJECTIVES: To investigate the cytoxicity of Ecasol using cultured keratinocyte monolayers and reconstituted human oral epithelial (RHE) tissue and to extend the study of Ecasol's effectiveness in maintaining the microbiological quality of DUWL output water. METHODS: TR146 human keratinocyte monolayers and RHE tissues were exposed to Ecasol (2.5-100 ppm) for 1h periods after removal of growth medium and washing with phosphate-buffered saline (PBS). Experiments were repeated using Ecasol that had been exposed for 30 min to 1-2mg/mL bovine serum albumin (BSA), equivalent to protein concentrations in saliva. To quantitatively determine cytotoxic effects on monolayers following Ecasol exposure, the Alamar Blue proliferation assay (assesses cell viability) and the Trypan Blue exclusion assay (assesses plasma membrane integrity), were used. Cytotoxicity effects on RHE tissues were assessed by the Alamar Blue assay and by histopathology. RESULTS: Ecasol at >5.0 ppm resulted in significant (P<0.001) cytotoxicity to keratinocyte monolayers following a 1h exposure. These effects, however, were completely negated by BSA pretreatment of Ecasol. No cytotoxicity was observed in the more complex RHE tissue at any of the Ecasol concentrations tested. In a 60-week study of 10 DCUs, tested weekly, the average density of aerobic heterotrophic bacteria in Ecasol-treated (2.5 ppm) DCU supply water was <1cfu/mL and in DUWL output water was 6.5cfu/mL. CONCLUSIONS: Ecasol present as a residual disinfectant in DUWL output water is very unlikely to have adverse effects on human oral tissues at levels effective in maintaining DUWL output water quality at better than potable standard water quality.

Synchronous oral carcinomas: independent or common clonal origin?

Second primary tumors in patients with head and neck cancer have a detrimental impact on long-term survival; at least 15% of patients develop additional tumors. Originally, it was hypothesized that multiple tumors developed independently after widespread epithelial exposure to carcinogens (the field cancerization theory), but recent molecular studies now support the alternative theory of a common clonal origin. If multiple tumors originate from the same clone, early genetic alterations in these cells should be common to all of the tumors. We have compared the pattern of allelic imbalance in paired tumors from five male patients with two synchronous oral squamous cell carcinomas and in peripheral dysplasia using microsatellite markers on chromosomes 3p, 9p, and 17p. Discordance, usually through loss of alternate alleles at the same microsatellite loci, was detected in two patients. The remaining three patients had identical alterations in their tumors. The changes identified occurred early in tumorigenesis, because, with only one exception, these were also present in the associated dysplasia. Thus, we provide evidence that synchronous oral squamous cell carcinomas are of independent origin in some patients but may be of common clonal origin in others.

Butyrate oxidation is impaired in the colonic mucosa of sufferers of quiescent ulcerative colitis.

The short chain fatty acids, acetate, propionate, and butyrate are produced by colonic bacterial fermentation of non-starch polysaccharides. Butyrate is the major fuel source for the colonic epithelium and there is evidence to suggest that its oxidation is impaired in ulcerative colitis. Triplicate biopsy specimens were taken at colonoscopy from five regions of the large bowel in 15 sufferers of ulcerative colitis. These patients all had mild or quiescent colitis as assessed by clinical condition, mucosal endoscopic and histological appearance. The rate of oxidation of glucose, glutamine, and butyrate through to carbon dioxide was compared with that in biopsy specimens from 28 patients who had no mucosal abnormality. Butyrate (272 (199-368)) was the preferred fuel source for the colitic mucosa followed by glutamine (33 (24-62)) then glucose (7.2 (5.3-15)) pmol/micrograms/hour; medians and 95% confidence intervals, p < 0.01. There was no regional difference in the rate of utilisation of these metabolites. In the group with colitis the rate of butyrate oxidation to carbon dioxide was significantly impaired compared with that in normal mucosa decreasing from 472 (351-637) pmol/micrograms/hour to 272 (199-368) pmol/micrograms/hour; median and 95% confidence intervals, p = 0.016. The rate of glucose and glutamine utilisation were not significantly different between normal and colitic mucosa. These data confirm that in quiescent ulcerative colitis there is an impairment of butyrate oxidation.