Coastal bathymetry in central Dronning Maud Land controls ice shelf stability.

Knowledge of the bathymetry of Antarctica's margins is crucial for models and interpretations of ice-ocean interactions and their influence on ongoing and future sea level change, but remains patchy where ice shelves and multi-year sea ice block measurements. Here, we present a bathymetric model for the central Dronning Maud Land margin, based on a constrained inversion of airborne gravity data. It shows the cavities beneath the region's two ice shelves to be much deeper than in existing bathymetric compilations, but to be shielded from Warm Deep Water ingress and basal melting by the presence of shallow bathymetric sills along the continental shelf. Over areas of multi-year sea ice, the model returns bathymetric estimates of similar accuracy to gravity interpolation-based methods over open water. Airborne gravity thus presents an opportunity to bathymetrically map hundreds of thousands of square kilometres of the most inaccessible margins of Antarctica at resolutions adequate for regional and global oceanographic and glaciological modelling and interpretation.

A prospective study of Clostridium difficile infection and colonization in pediatric oncology patients.

BACKGROUND: Patients with cancer often receive broad spectrum antibiotics in addition to antineoplastic chemotherapy. Both treatments predispose adult oncology patients to infection and colonization with Clostridium difficile, but the role of this pathogen in pediatric oncology patients is poorly defined. METHODS: A prospective study of 149 fecal samples from symptomatic pediatric oncology patients and 58 samples from asymptomatic patients was performed. Each sample was analyzed for the presence of C. difficile and its toxins A and B. RESULTS: In 8.7% of the symptomatic samples and 19% of the asymptomatic samples toxigenic C. difficile was found. No association was found between either the use of antibiotics and/or the administration of chemotherapy and the presence of toxigenic C. difficile. Younger children were more likely to be infected or colonized with C. difficile, and there was no evidence of nosocomial transmission of C. difficile within the study population. CONCLUSIONS: As toxigenic C. difficile may form part of the normal flora in young children, this study indicates that in the absence of a defined outbreak, C. difficile does not appear to be an important pathogen in pediatric oncology patients.

Outbreak of extended spectrum beta lactamase producing Klebsiella pneumoniae in a neonatal unit.

An outbreak of extended spectrum beta lactamase producing Klebsiella pneumoniae (ESBLKp) in a neonatal unit was controlled using simple measures. Normally, the control of such infections can be time consuming and expensive. Seven cases of septicaemia resulted in two deaths. ESBLKp isolates were subtyped by pulsed field gel electrophoresis, and four of the five isolates typed were identical. Control of the outbreak was achieved by altered empiric antibiotic treatment for late onset sepsis and prevention of cross infection by strict attention to hand washing. Widespread colonisation of babies in the unit was presumed, so initial surveillance cultures were not performed. No further episodes of sepsis occurred.

Epidemiology of Cryptosporidium parvum in symptomatic paediatric oncology patients.

BACKGROUND: Although Cryptosporidium parvum is known to cause significant morbidity in immunocompromised individuals, including adults with cancer, the epidemiology of this pathogen in paediatric oncology patients is not known. OBJECTIVE: We prospectively investigated the incidence of symptomatic C. parvum infection in children receiving treatment for malignancy. METHODOLOGY: Over a 9 month period, all oncology inpatients with diarrhoea had stool analysis for C. parvum oocysts. The incidence of cryptosporidiosis was also recorded in non-oncology patients who had a stool analysed for C. parvum during the 6 years of the study period. RESULTS: None of the 149 stool samples from 60 oncology patients analysed contained C. parvum oocysts. Thirteen per cent of 173 samples from non-oncology patients were positive for C. parvum oocysts. CONCLUSIONS: In contrast to studies of adult oncology patients, paediatric oncology patients in our institution appear at low risk of cryptosporidiosis.

Listeriosis--a review of eighty-four cases.

OBJECTIVE: To review the epidemiology, risk factors for acquisition, clinical features and outcomes of Listeria monocytogenes infection in Sydney. DESIGN: A retrospective study over the period 1983-1992 at four university teaching hospitals in Sydney. Cases were identified from microbiology laboratory records of the isolation of L. monocytogenes from sterile sites. RESULTS: Eighty-four cases were reviewed, with 72 patients (86%) having a predisposing underlying condition, including 13 perinatal patients (15%). Septicaemia (56%) and central nervous system disease (41%) were the major clinical presentations. Nineteen patients (23%) had hospital-associated infection. A mortality of 21% (18 patients) was directly attributable to L. monocytogenes infection, with another 10% (nine patients) dying of their underlying disease during admission. The 84 cases represented 80% of all L. monocytogenes cases occurring in Sydney during the study period. CONCLUSIONS: Listeriosis is predominantly a disease of the elderly or of immunosuppressed individuals, pregnant women and neonates. The presentation and outcome in these groups are similar to those reported in other Western countries. A significant feature of this study was the number of cases occurring in already hospitalised patients, suggesting that L. monocytogenes may be an important hospital-associated pathogen in immunocompromised patients.

Disseminated invasive infection due to Metarrhizium anisopliae in an immunocompromised child.

The first reported human case of possible disseminated infection with the insect pathogen Metarrhizium anisopliae var. anisopliae, a fungus which has been used commercially for biocontrol of insects, is described. The patient, a 9-year-old boy, had a 5-year history of pre-B-cell acute lymphoblastic leukemia and had been on chemotherapy throughout this period. After 10 days of profound neutropenia, lesions consistent with ecthyma gangrenosum appeared on his arms and legs. M. anisopliae was grown from specimens from three separate sites, collected at different times over a period of 1 month: a skin biopsy, a swab from the base of a lesion, and the core of another skin lesion which spontaneously discharged. The initial skin biopsy also showed histological evidence of epidermal necrosis and dermal invasion with fungal hyphae. A computed-tomography (CT) scan of the chest demonstrated a lesion in the superior segment of the lower lobe of the left lung. A CT scan of the brain revealed a lesion in the left temporoparietal region of the brain, consistent with an abscess. Despite antifungal treatment including liposomal amphotericin and 5-flucytosine, the patient eventually died. The initial portal of entry is unknown, but hematogenous dissemination to the skin appears likely because of the multiple ecthymic lesions, and the appearances of the brain lesion on the CT scan are consistent with a hematogenous fungal abscess.

Hepatocyte growth factor/scatter factor is present in most pleural effusion fluids from cancer patients.

Pleural effusion samples were obtained from 55 patients with malignant disease, including patients with primary lung cancers and those with a variety of other tumours metastatic to the pleura. The effusions were assayed for the presence of hepatocyte growth factor/scatter factor (HGF/SF), by both ELISA and bioassay. The presence of malignant cells in the effusions was also assessed. Detectable amounts of the factor, as judged by both criteria, were found in over 90% of all the effusions, including those from patients with a wide variety of carcinomas and also lymphomas. A wide range of HGF/SF levels were found for all tumour classes, some effusions containing high levels above 4 ng ml-1. It is concluded that tumours within the pleura and adjacent lung tissue are usually exposed to biologically significant levels of HGF/SF.