Fifteen-minute consultation: A structured approach to the child with palpable cervical lymph nodes

Palpable cervical lymph nodes are common in children and are a frequent reason for presentation to both primary and secondary care. Enlarged lymph nodes are most commonly the result of self-limiting infection, and in children, are rarely the first indicator of a malignant process. This article presents an evidenced-based approach to evaluating these patients.

Controversial aspects of imaging in child abuse: a second roundtable discussion from the ESPR child abuse taskforce

This second roundtable discussion was convened at the 56th European Society of Paediatric Radiology (ESPR) 2022 Annual Meeting in Marseille, France, to discuss controversial aspects of imaging in child abuse. The following topics were discussed: Fracture dating-the published literature is broadly similar with respect to the identification of the radiographic stages of bony healing. The non-expert/general radiologist is encouraged to use broad descriptors of fracture healing (acute, healing or old) within their reports, rather than attempting to date fractures. The more experienced/expert radiologist, who may provide a timeframe/range to assist the courts, should be aware that any published timeframes are not absolute and that recent research indicates that the rate of healing may differ according to the bone affected and the age of the patient. Whole spine imaging in suspected abusive head trauma-this is recommended to enable a complete assessment of the neuraxis when abusive head trauma is suspected or diagnosed, particularly in the presence of intracranial and cervical subdural haemorrhage and cervical ligamentous injury. Cranial imaging in suspected physical abuse-both computed tomography (CT) and magnetic resonance imaging (MRI) remain complimentary depending on the clinical context in which they are used with CT remaining first-line in the assessment of children with (suspected abusive) head trauma prior to an early MRI. MRI is superior in its assessment of parenchymal injury and may be employed as first-line in age appropriate asymptomatic siblings of a child with suspected physical abuse.

Benign enlargement of the subarachnoid spaces and subdural collections-when to evaluate for abuse

In infants without a history of trauma, subdural haemorrhages should raise the concern for an abusive head injury, particularly when they are associated with bridging vein clotting/rupture or with septations. However, non-haemorrhagic, fluid-appearing subdural collections (also called hygromas) may also be the result of abuse. Subdural collections have also been uncommonly observed in patients with benign enlargement of the subarachnoid spaces (BESS) and a few large-scale studies accurately investigate the incidence and the significance. Currently, there is a wide variation of practices in children with BESS and subdural collections. Due to the social risks associated with abuse evaluation and the perceived risk of radiation exposure, there might be a reluctance to fully evaluate these children in some centres. The diagnosis of physical abuse cannot be substantiated nor safely excluded in infants with BESS and subdural collection(s), without investigation for concomitant traumatic findings. The exact prevalence of occult injuries and abuse in these infants is unknown. In macrocephalic infants with subdural collections and imaging features of BESS, thorough investigations for abuse are warranted and paediatricians should consider performing full skeletal surveys even when fundoscopy, social work consult, and detailed clinical evaluation are unremarkable.

Professional practice and awareness of child abuse among radiologists and radiologic technologists: results from Saudi Arabia

BACKGROUND

The knowledge, awareness and professionalism of health care providers in the field of child protection are crucial in identifying and reporting suspected child abuse. Radiologic technologists and radiologists play a vital role in the diagnosis of suspected physical child abuse.

OBJECTIVE

To assess current practice, knowledge and awareness of child abuse among radiologic technologists and radiologists in Saudi Arabia.

MATERIALS AND METHODS

We distributed an internet-based questionnaire to radiologic technologists and radiologists working in Saudi Arabia via national radiology societies and social media channels over a 6-week period (27 October to 8 December 2021). Survey questions covered knowledge regarding child abuse, professional practice in radiology departments in Saudi Arabia in cases of suspected physical abuse (SPA), and knowledge of the national legislation and reporting and acting procedures in child abuse.

RESULTS

A total of 315 respondents (224 radiologic technologists and 91 radiologists) participated in this study. The median score for knowledge of abuse was higher amongst radiologists (4.8) than radiologic technologists (4.0); P < 0.001. In total, 210 (93.8%) radiologic technologists and 61 (67.0%) radiologists reported that there was no protocol (i.e. skeletal survey) at their hospital for imaging children with SPA. Most radiologic technologists had no training in paediatric radiology (165/224, 73.7%) and most radiologists had received no training in evaluating imaging performed for SPA (73/91, 80.2%). More than half of respondents - 131 (58.5%) radiologic technologists and 44 (48.4%) radiologists - were not familiar with the reporting and acting procedures at their hospitals in cases of child abuse.

CONCLUSION

Although radiologic technologists and radiologists in Saudi Arabia have good knowledge and awareness of child abuse in general, they lack specific knowledge of the reporting and acting procedures at their hospitals in cases of suspected child abuse. National imaging guidelines and training courses are needed to develop appropriate skills in the recognition, imaging and reporting of SPA in infants and young children in Saudi Arabia.

The diagnostic performance of chest computed tomography in the detection of rib fractures in children investigated for suspected physical abuse: a systematic review and meta-analysis

Objectives

To assess the diagnostic performance of chest CT in the detection of rib fractures in children investigated for suspected physical abuse (SPA).

Methods

Medline, Web of Science and Cochrane databases were searched from January 1980 to April 2020. The QUADAS-2 tool was used to assess the quality of the eligible English-only studies following which a formal narrative synthesis was constructed. Studies reporting true-positive, false-positive, true-negative, and false-negative results were included in the meta-analysis. Overall sensitivity and specificity of chest CT for rib fracture detection were calculated, irrespective of fracture location, and were pooled using a univariate random-effects meta-analysis. The diagnostic accuracy of specific locations along the rib arc (anterior, lateral or posterior) was assessed separately.

Results

Of 242 identified studies, 4 met the inclusion criteria. Of these, 2 were included in the meta-analysis. Chest CT identified 142 rib fractures compared to 79 detected by initial skeletal survey chest radiographs in live children with SPA. Post-mortem CT (PMCT) has low sensitivity (34%) but high specificity (99%) in the detection of rib fractures when compared to the autopsy reference standard. PMCT has low sensitivity (45%, 21% and 42%) but high specificity (99%, 97% and 99%) at anterior, lateral and posterior rib locations, respectively.

Conclusions

Chest CT detects more rib fractures than initial skeletal survey chest radiographs in live children with SPA. PMCT has low sensitivity but high specificity for detecting rib fractures in children investigated for SPA.

Key Points

• PMCT has low sensitivity (34%) but high specificity (99%) in the detection of rib fractures; extrapolation to CT in live children is difficult.

• No studies have compared chest CT with the current accepted practice of initial and follow-up skeletal survey chest radiographs in the detection of rib fractures in live children investigated for SPA.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00330-021-07775-3.

Immediate chest radiograph interpretation by radiographers improves patient safety related to nasogastric feeding tube placement in children

BACKGROUND

Despite the publication of a national patient safety alert in 2016, inadvertent feeding through misplaced nasogastric tubes continues to occur, either through failure to review the radiograph, misinterpretation of it, or failure to communicate the results.

OBJECTIVE

The objectives were to determine whether training in a new pathway introduced to avoid these "never events" was followed and whether radiographer comments and prompt communication of results could reduce risk and improve patient safety in relation to nasogastric tube placement in children.

MATERIALS AND METHODS

Following radiographer training in interpretation of nasogastric tube position and use of a commenting proforma and communication pathway, we reviewed all radiographs obtained to check nasogastric tubes performed over a 13-month period in children 0-16 years of age. Then we assessed accuracy of the radiographer comments, adherence to the pathway, and any practice change in children with misplaced nasogastric tubes.

RESULTS

We reviewed 282 nasogastric tube check radiographs. For 262 radiographs (92.9%) the pathway was followed correctly. Of the total 282 radiographs, 240 (85%) were immediately reported using the standardised commenting proforma, and 235 radiographer comments were affirmed by the radiologist (97% accuracy, confidence interval 0.95-0.99). Of the immediately reported radiographs, 213 (88.8%) nasogastric tubes were considered to be safe for use. Four (1.7%) of the immediately reported nasogastric tubes were misplaced in a bronchus, and the report communicated to the clinical team resulted in removal or re-siting of the tubes.

CONCLUSION

Nasogastric tube check radiographs in children can be reported accurately by radiographers trained in their interpretation and the results promptly communicated to clinical staff, improving safety in relation to nasogastric tube placement in children.

Shortage of paediatric radiologists acting as an expert witness: position statement from the British Society of Paediatric Radiology (BSPR) National Working Group on Imaging in Suspected Physical Abuse (SPA)

One of the most challenging areas of radiological imaging in children is the diagnosis of physical abuse. There is a dearth of paediatric radiologists willing to act as expert witnesses, particularly in the family courts. There are a number of reasons why radiologists may not be interested or willing to put themselves forward to work as expert witnesses in this field. A group of imaging experts recently formed the "British Society of Paediatric Radiology (BSPR) Working Group on Imaging in Suspected Physical Abuse (SPA)". The group comprises radiologists and neuroradiologists with current or previous experience of providing expert witness reports to the court in cases of SPA. The group met in January 2019 to explore pragmatic solutions to the chronic inefficiencies in both medical and legal practices and the challenges that arise from working in a legal arena with different structures, goals, and assessment criteria. Key issues concerned organisational inefficiencies, variable support from National Health Service Trusts and the Royal College of Radiologists to conduct this work, and the risk/benefit of involvement. This work is important for the patient, parents, and society in general, and highly rewarding for clinical practitioners who are involved, but there are several issues with current practices that discourage active participation. With several members of the group either retired or close to retirement, the shortage of experts is becoming a pressing issue within the UK, which requires an engaged multidisciplinary group to come up with creative solutions. Here, the group provide a consensus opinion highlighting the current barriers and potential facilitators to increasing the number of radiologists willing to provide opinions to the court.

Duration of intravenous antibiotic therapy for children with acute osteomyelitis or septic arthritis: a feasibility study

BACKGROUND

There is little current consensus regarding the route or duration of antibiotic treatment for acute osteomyelitis (OM) and septic arthritis (SA) in children.

OBJECTIVE

To assess the overall feasibility and inform the design of a future randomised controlled trial (RCT) to reduce the duration of intravenous (i.v.) antibiotic use in paediatric OM and SA.

DESIGN

(1) A prospective service evaluation (cohort study) to determine the current disease spectrum and UK clinical practice in paediatric OM/SA; (2) a prospective cohort substudy to assess the use of targeted polymerase chain reaction (PCR) in diagnosing paediatric OM/SA; (3) a qualitative study to explore families' views and experiences of OM/SA; and (4) the development of a core outcome set via a systematic review of literature, Delphi clinician survey and stakeholder consensus meeting.

SETTING

Forty-four UK secondary and tertiary UK centres (service evaluation).

PARTICIPANTS

Children with OM/SA.

INTERVENTIONS

PCR diagnostics were compared with culture as standard of care. Semistructured interviews were used in the qualitative study.

RESULTS

Data were obtained on 313 cases of OM/SA, of which 218 (61.2%) were defined as simple disease and 95 (26.7%) were defined as complex disease. The epidemiology of paediatric OM/SA in this study was consistent with existing European data. Children who met oral switch criteria less than 7 days from starting i.v. antibiotics were less likely to experience treatment failure (9.6%) than children who met oral switch criteria after 7 days of i.v. therapy (16.1% when switch was between 1 and 2 weeks; 18.2% when switch was > 2 weeks). In 24 out of 32 simple cases (75%) and 8 out of 12 complex cases (67%) in which the targeted PCR was used, a pathogen was detected. The qualitative study demonstrated the importance to parents and children of consideration of short- and long-term outcomes meaningful to families themselves. The consensus meeting agreed on the following outcomes: rehospitalisation or recurrence of symptoms while on oral antibiotics, recurrence of infection, disability at follow-up, symptom free at 1 year, limb shortening or deformity, chronic OM or arthritis, amputation or fasciotomy, death, need for paediatric intensive care, and line infection. Oral switch criteria were identified, including resolution of fever for ≥ 48 hours, tolerating oral food and medicines, and pain improvement.

LIMITATIONS

Data were collected in a 6-month period, which might not have been representative, and follow-up data for long-term complications are limited.

CONCLUSIONS

A future RCT would need to recruit from all tertiary and most secondary UK hospitals. Clinicians have implemented early oral switch for selected patients with simple disease without formal clinical trial evidence of safety. However, the current criteria by which decisions to make the oral switch are made are not clearly established or evidence based.

FUTURE WORK

A RCT in simple OM and SA comparing shorter- or longer-course i.v. therapy is feasible in children randomised after oral switch criteria are met after 7 days of i.v. therapy, excluding children meeting oral switch criteria in the first week of i.v. therapy. This study design meets clinician preferences and addresses parental concerns not to randomise prior to oral switch criteria being met.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Hand hygiene compliance monitoring in anaesthetics: Feasibility and validity

Background:

Hand hygiene compliance scores in the anaesthetic department of an acute NHS hospital were persistently low.

Aims:

To determine the feasibility and validity of regular accurate measurement of HHC in anaesthetics and understand the context of care delivery, barriers and opportunities to improve compliance.

Methods:

The hand hygiene compliance of one anaesthetist was observed and noted by a senior infection control practitioner (ICP). This was compared to the World Health Organization five moments of hand hygiene and the organisation hand hygiene tool.

Findings:

In one sequence of 55 min, there were approximately 58 hand hygiene opportunities. The hand hygiene compliance rate was 16%. The frequency and speed of actions in certain periods of care delivery made compliance measurement difficult and potentially unreliable. During several activities, taking time to apply alcohol gel or wash hands would have put the patients at significant risk.

Discussion:

We concluded that hand hygiene compliance monitoring by direct observation was invalid and unreliable in this specialty. It is important that hand hygiene compliance is optimal in anaesthetics particularly before patient contact. Interventions which reduce environmental and patient contamination, such as cleaning the patient and environment, could ensure anaesthetists encounter fewer micro-organisms in this specialty.

Motivation and job satisfaction of cleaning staff in the NHS: a pilot study

Fourteen NHS hospital ward cleaning staff were interviewed about their background, job satisfaction and motivation as part of the evaluation of a new cleaning system. Four (28%) staff had attended university, five (35%) had no qualifications and the remainder had a range of educational attainments. Nine (64%) did the job to earn money, three (22%) because they liked it and two (14%) because there were no other opportunities. Repetitive tasks were undertaken routinely with tight control of method and order of working. The work was tiring and ad hoc requests increased the burden. Although all staff knew what was expected of them in their job, nine (62%) reported they “knew themselves” if they had done a good job as feedback was frequently absent or belated. Opportunities including access to the internet were limited and long hours doing extra work reduced free time. This pilot study highlights the potential of these healthcare cleaning professionals to contribute and develop given the opportunities.

Severe invasive Panton-Valentine Leucocidin positive Staphylococcus aureus infections in children in London, UK

OBJECTIVE

To describe the features of invasive Panton-Valentine Leucocidin positive Staphylococcus aureus (PVL-SA) in children at a London teaching hospital, from 2004 to 2008.

METHODS

Retrospective case note review.

RESULTS

Eleven previously healthy children, 7 male, median age 9 years (range 7 months-13 years), had invasive infections due to unrelated community-acquired meticillin-sensitive PVL-SA. Possible risk factors were identified in 10 cases. Eight patients had complicated musculoskeletal infections, 2 had pneumonia, and 1 had a massive retropharyngeal abscess. At admission neutropenia was present in 2 patients, deep vein thrombosis in 3, and initial blood cultures were positive in 8. Patients with musculoskeletal involvement had a median of 3 (range 1-6) sites of infection, and required median 5 (range 1-11) operative procedures. Eight patients were admitted to PICU, 7 had septic shock. Median duration of hospital stay was 51 (range 14-255) days. One child died and 5 have long-term morbidity.

CONCLUSIONS

The clinical features of invasive PVL-SA in this series were similar to those reported from USA and Europe. Musculoskeletal infection was the most common manifestation, frequently progressing to multiple sites and severe sepsis. Most cases had risk factors and clinical features which might have allowed earlier diagnosis, and possibly improved outcome.

Cadherins and cancer: how does cadherin dysfunction promote tumor progression?

It has long been recognized that the cell-cell adhesion receptor, E-cadherin, is an important determinant of tumor progression, serving as a suppressor of invasion and metastasis in many contexts. Yet how the loss of E-cadherin function promotes tumor progression is poorly understood. In this review, we focus on three potential underlying mechanisms: the capacity of E-cadherin to regulate beta-catenin signaling in the canonical Wnt pathway; its potential to inhibit mitogenic signaling through growth factor receptors and the possible links between cadherins and the molecular determinants of epithelial polarity. Each of these potential mechanisms provides insights into the complexity that is likely responsible for the tumor-suppressive action of E-cadherin.

Impact of rapid molecular screening for meticillin-resistant Staphylococcus aureus in surgical wards

Background

This study aimed to establish the feasibility and cost-effectiveness of rapid molecular screening for hospital-acquired meticillin-resistant Staphylococcus aureus (MRSA) in surgical patients within a teaching hospital.

Methods

In 2006, nasal swabs were obtained before surgery from all patients undergoing elective and emergency procedures, and screened for MRSA using a rapid molecular technique. MRSA-positive patients were started on suppression therapy of mupirocin nasal ointment (2 per cent) and undiluted chlorhexidine gluconate bodywash.

Results

A total of 18 810 samples were processed, of which 850 (4·5 per cent) were MRSA positive. In comparison to the annual mean for the preceding 6 years, MRSA bacteraemia fell by 38·5 per cent (P &lt; 0·001), and MRSA wound isolates fell by 12·7 per cent (P = 0·031). The reduction in MRSA bacteraemia and wound infection was equivalent to a saving of 3·78 beds per year (£276 220), compared with the annual mean for the preceding 6 years. The cost of screening was £302 500, making a net loss of £26 280. Compared with 2005, however, there was a net saving of £545 486.

Conclusion

Rapid MRSA screening of all surgical admissions resulted in a significant reduction in staphylococcal bacteraemia during the screening period, although a causal link cannot be established.

Marketing hand hygiene in hospitals--a case study

Hand hygiene of healthcare workers is frequently poor despite the efforts of infection control teams to promote hand decontamination as the most important method to prevent transmission of hospital-acquired infections. In this case study, we describe how principles of societal marketing were applied to improve hand hygiene. Pre-marketing analysis of strengths, weaknesses, opportunities and threats to implementation; attention to product, price, promotion and placement; and post-marketing 'customer' surveys were the essential components of the marketing strategy and its implementation. Placement of an alcohol-based gel decontaminant (Spirigel) at the bedside of every patient was widely welcomed in the hospital, and has played a major role in improving hand hygiene of healthcare workers. In the twelve months following the implementation, the decontaminant was used at least 440,000 times. The cost of purchasing the decontaminant was approximately 5000 pounds sterling. Following the introduction of Spirigel, there was a consistent reduction in the proportion of hospital-acquired methicillin-resistant Staphylococcus aureus (MRSA) in each of the quarters of 2000-2001 compared with 1999-2000. In the period 1999-2000, nearly 50% of the MRSA were hospital acquired compared with 39% in 2000-2001. Similarly, the average incidence of Clostridium difficile associated diarrhoea (CDAD) decreased in each of the quarters in 2000-2001 following the introduction of Spirigel. During this period, there was an average incidence of 9.5 cases of CDAD/1000 admissions compared with 11.5 cases of CDAD/1000 admissions in 1999-2000. This represents a 17.4% reduction in the incidence of CDAD. However, this reduction was not statistically significant (P=0.2). Our case study demonstrates that principles of societal marketing methods can be used effectively to promote and sustain hand hygiene in hospitals. Improvement in hand hygiene will lead to considerable reduction in hospital-acquired infections.

Nail art: a review of current infection control issues

Nail art or nail technology is a form of nail decoration which frequently entails applying extensions to the natural nail and then adding decorative effects. There have been a number of outbreaks of infection which have implicated nail art. These infections are likely to be as a result of difficulties in cleaning and maintaining the nail extensions. Nail art appears to be incompatible with clinical care.

Use of first line bronchoalveolar lavage in the immunosuppressed oncology patient

Immunosuppressed oncology patients who develop pulmonary infiltrates during treatment have a mortality rate of the order of 55-90%. Early diagnosis and treatment is associated with increased survival. At present, diagnosis relies on invasive sampling of the respiratory tract using fibre-optic bronchoscopy. We have looked at a 30-month period, from June 1997 to December 1999, where 25 bronchoscopies were performed on patients from the Lymphoma and BMT units at The Royal Marsden Hospital for the further investigation of pulmonary infiltrates. Nine bronchoscopies (36%) yielded a positive result and seven (28%) led to a change in management. Analysis of the data showed that neither a positive result nor a change in management had any impact on overall survival. After reviewing the background literature on the investigation of pulmonary infiltrates in this group and discussion of the respective merits and limitations, we propose a management flowchart, with high-resolution computed tomography (HRCT) as the test arm in a future randomised trial of these patients.

Rational protocols for testing faeces in the investigation of sporadic hospital-acquired diarrhoea

Many recent studies have demonstrated that routine examination of faeces for conventional enteric pathogens such as salmonella, shigella, campylobacter and parasites in patients who develop sporadic hospital-acquired diarrhoea is unnecessary and wasteful. In this paper the advantages and disadvantages of a restricted testing protocol in patients with hospital-acquired diarrhoea are reviewed. Practical issues for safe implementation of such a protocol are also discussed.

Zero-Stik-Safety Syringe: an automatic safety syringe

Needlestick injury (NSI) is an important although rare cause of the transmission of blood-borne viruses to healthcare staff. Many NSIs are avoidable. The use of universal precautions and careful sharps disposal are key factors in the prevention of injury. The availability of safety devices is increasing as it is recognized that action is necessary to prevent NSI. Devices that are easy to use and require no extra effort on behalf of the healthcare worker are preferred. There is evidence that safety devices decrease the rate of NSI. Zero-Stik Safety Syringe, manufactured by New Medical Technology, automatically retracts the needle once the injection is complete. It is simple to use and requires no formal training.

Know how latex sensitisation

The problem of latex sensitisation in health-care settings is now well documented. Nurses need to be aware of the types of reactions that can occur in those who are sensitised to latex and know the appropriate measures to take to relieve the symptoms, while employers should have a policy on latex sensitisation to ensure the safety and well-being of employees and patients.

Immunochemical and related interactions with dextrans reviewed in terms of improved structural information

Structurally diverse dextrans from Leuconostoc mesenteroides and related bacteria have been used extensively in fundamental immunochemical studies such as induction and characterization of anti-dextran antibodies, as well as in studies of their interaction with pneumococcal antisera, normal bovine serum, concanavalin A, dextran-binding myeloma immunoglobulins and hybridoma antibodies. The inherent lack of specificity of structural data obtained by POSA and general lack of insight into other limitations of these analyses has often led to inaccurate and superficial interpretations. Proper interpretation of past and future studies necessitates pointing out previous inadequacies of dextran structural data and detailing more recently acquired structural information on the dextrans. Unambiguous terminology has been achieved by a new system of linkage symbols that includes the designation of structural positions, such as (1----3; l)- and (1----3; b) as linear-chain and branch-point positions, respectively. Results of immunological studies are reviewed. Improved interpretations and correlations are made on the basis of structural data from MSA and several other techniques which have become available on the dextrans.

Colonial variation in Xanthomonas campestris NRRL B-1459 and characterization of the polysaccharide from a variant strain

Stock cultures of Xanthomonas campestris NRRL B-1459 require special attention to maintenance and propagation to assure consistent production in good yields of the extracellular polysaccharide xanthan. Under customary conditions of propagative maintenance on agar slants, variant colony types develop that are smaller in size than the normal type. The rate of regression of the normal to the variant forms was diminished when the D-glucose content of the stock medium was sufficient to avoid depletion during storage and when transfer to fresh medium was reduced to 14-day intervals. Under conditions for polysaccharide production, the normal large-colony type gives crude culture liquors after 48 h of 7000 centipoise (cp) viscosity; the predominant variant form gives only 4000 cp. On the basis of 2.1% initial D-glucose, biopolymer yields for the normal and variant strains were 62 and 43%, respectively. Polysaccharide produced by the variant (small-colony type) differs adversely in solution properties from that of the parent strain (large-colony type); it differs also in its lower content of pyruvic acid and O-acetyl substituents. The molar ratios of constituent sugars (D-glucose, D-mannose, and D-glucuronic acid), however, were identical in polysaccharides with the normal and variant strains. Exclusion of colonial variants from fermentations is prerequisite to production of xanthan optimum in properties and yield.

An extracellular fungal polysaccharide composed of 2-acetamido-2-deoxy-D-glucuronic acid residues

The black yeast-like fungus NRRL YB-4163, now tentatively identified as Rhinocladiella elatior Mangenot, has been found to produce an extracellular microbial polysaccharide composed mainly of 2-acetamido-2-deoxy-D-glucuronic acid residues. Polysaccharide (PS) YB-4163, when isolated in good yield as the neutral potassium salt, dissolves readily in water to produce extremely viscous solutions, which form stable foams and emulsions. By depolymerizing PS YB-4163 with [14C]methanol-HCl, the polysaccharide can be both identified and quantitated radiochemically by determining the individual [14C]methyl glycosides after their separation by paper chromatography. When the methyl glycosides of PS YB-4163 were reduced with NaB3H4, only the methyl glycosides of 2-acetamido-2-deoxy-D-[6-3H]glucose were found. Analysis of the monosaccharide released from carboxyl-reduced PS YB-4163 by acid hydrolysis or methanolysis also showed 2-acetamido-2-deoxy-D-glucuronic acid to be the main constituent. Previously, the only polysaccharides known to be composed entirely or hexosaminuronic acid have been cellular products from pathogens. Of these, the antigenic polysaccharide (SPSA) from Staphylococcus aureus is composed entirely of 2-amino-2-deoxy-D-glucuronic acid, but its amino groups are substituted equally with acetyl and N-acetylalanyl groups. The specific optical rotation of PS YB-4163, [alpha]20D -75 degrees (c 0.5, water), is similar to that of SPSA (-91 degrees), and suggests beta-D-linkages that must be either (1 leads to 3) or (1 leads to 4).

Extracellular polysaccharide from the black yeast NRRL Y-6272: improved methods for preparing a high-viscosity, pigment-free product

When the extracellular polysaccharide from the black yeast NRRL Y-6272, composed of two parts N-acetyl-D-glucosamine and one part N-acetyl-D-glucosaminuronic acid, is isolated at maximum culture viscosity, adhering black pigment gives the polysaccharide preparations a gray-to-black appearance. Precipitation of the polysaccharide from cell-free culture supernatants with either ethanol of hexadecyltrimethylammonium bromide failed to remove the pigment. Various other methods were therefore tried for obtaining a high-viscosity polysaccharide product free of pigment. By systematically varying ingredients of defined and semidefined media, an improved medium was found that not only gave polysaccharide preparations of increased viscosity, but also increased yield. A key ingredient in this medium is L-asparagine. Also, adding autoclaved bovine serum albumin or egg albumin to this medium at the time of inoculation allowed a pigment-free polysaccharide to be isolated by standard procedures. None of several other proteins of synthetic polyamides tested were as effective as bovine serum albumin or egg albumin. In an alternate approach, pink mutants obtained by irradiation of the parent black strain with ultraviolet light, apparently produce the same extracellular polysaccharide free of any pigment but in lower yields or inferior in quality.