Air dispersal of multi-drug-resistant organisms including meticillin-resistant Staphylococcus aureus, carbapenem-resistant Acinetobacter baumannii and carbapenemase-producing Enterobacterales in general wards: surveillance culture of air grilles.

BACKGROUND: The environmental surveillance of air grilles in clinical areas has not been systematically analysed. METHODS: Samples were collected from frequently touched items (N = 529), air supply (N = 295) and exhaust (N = 184) grilles in six medical and 11 surgical wards for the cultures of multi-drug-resistant organisms (MDROs): meticillin-resistant Staphylococcus aureus (MRSA), carbapenem-resistant Acinetobacter baumannii (CRAB) and carbapenemase-producing Enterobacterales (CPE), and isolates were selected for whole-genome sequencing (WGS). The contamination rates were correlated with the colonization pressures of the respective MDROs. RESULTS: From 3rd October to 21st November 2023, 9.8% (99/1008) of the samples tested positive, with MRSA (24.2%, 24/99), CRAB (59.6%, 59/99) and CPE (2.0%, 2/99), being the only detected MDROs. The contamination rate in air exhaust grilles (26.6%, 49/184) was significantly higher than in air supply grilles (5.8%, 17/295; P<0.001). The contamination rate of air exhaust grilles with any MDRO in acute medical wards (73.7%, 14/19) was significantly higher than in surgical wards (12.5%, 4/32; P<0.001). However, there was no difference in the contamination rate of air exhaust grilles between those located inside and outside the cohort cubicles for MDROs (27.1%, 13/48 vs 28.8%, 30/104; P=0.823). Nevertheless, the weekly CRAB colonization pressure showed a significant correlation with the overall environmental contamination rate (r = 0.878; 95% confidence interval (CI): 0.136-0.986; P=0.004), as well as with the contamination rate in air supply grilles (r = 0.960; 95% CI: 0.375-0.999; P<0.001) and air exhaust grilles (r = 0.850; 95% CI: 0.401-0.980; P=0.008). WGS demonstrated clonal relatedness of isolates collected from patients and air exhaust grilles. CONCLUSIONS: Air grilles may serve as MDRO reservoirs. Cohort nursing in open cubicles may not completely prevent MDRO transmission through air dispersal, prompting the consideration of future hospital design.

Air dispersal of meticillin-resistant Staphylococcus aureus in residential care homes for the elderly: implications for transmission during the COVID-19 pandemic.

BACKGROUND: Meticillin-resistant Staphylococcus aureus (MRSA) infections are rampant in hospitals and residential care homes for the elderly (RCHEs). AIM: To analyse the prevalence of MRSA colonization among residents and staff, and degree of environmental contamination and air dispersal of MRSA in RCHEs. METHODS: Epidemiological and genetic analysis by whole-genome sequencing (WGS) in 12 RCHEs in Hong Kong. FINDINGS: During the COVID-19 pandemic (from September to October 2021), 48.7% (380/781) of RCHE residents were found to harbour MRSA at any body site, and 8.5% (8/213) of staff were nasal MRSA carriers. Among 239 environmental samples, MRSA was found in 39.0% (16/41) of randomly selected resident rooms and 31.3% (62/198) of common areas. The common areas accessible by residents had significantly higher MRSA contamination rates than those that were not accessible by residents (37.2%, 46/121 vs. 22.1%, 17/177, P=0.028). Of 124 air samples, nine (7.3%) were MRSA-positive from four RCHEs. Air dispersal of MRSA was significantly associated with operating indoor fans in RCHEs (100%, 4/4 vs. 0%, 0/8, P=0.002). WGS of MRSA isolates collected from residents, staff and environmental and air samples showed that ST 1047 (CC1) lineage 1 constituted 43.1% (66/153) of all MRSA isolates. A distinctive predominant genetic lineage of MRSA in each RCHE was observed, suggestive of intra-RCHE transmission rather than clonal acquisition from the catchment hospital. CONCLUSION: MRSA control in RCHEs is no less important than in hospitals. Air dispersal of MRSA may be an important mechanism of dissemination in RCHEs with operating indoor fans.

Retinoic acid induces down-regulation of Wnt-3a, apoptosis and diversion of tail bud cells to a neural fate in the mouse embryo.

The tail bud comprises the caudal extremity of the vertebrate embryo, containing a pool of pluripotent mesenchymal stem cells that gives rise to almost all the tissues of the sacro-caudal region. Treatment of pregnant mice with 100 mg/kg all-trans retinoic acid at 9.5 days post coitum induces severe truncation of the body axis, providing a model system for studying the mechanisms underlying development of caudal agenesis. In the present study, we find that retinoic acid treatment causes extensive apoptosis of tail bud cells 24 h after treatment. Once the apoptotic cells have been removed, the remaining mesenchymal cells differentiate into an extensive network of ectopic tubules, radially arranged around the notochord. These tubules express Pax-3 and Pax-6 in a regionally-restricted pattern that closely resembles expression in the definitive neural tube. Neurofilament-positive neurons subsequently grow out from the ectopic tubules. Thus, the tail bud cells remaining after retinoic acid-induced apoptosis appear to adopt a neural fate. Wnt-3a, a gene that has been shown to be essential for tail bud formation, is specifically down-regulated in the tail bud of retinoic acid-treated embryos, as early as 2 h after retinoic acid treatment and Wnt-3a transcripts become undetectable by 10 h. In contrast, Wnt-5a and RAR-gamma are still detectable in the tail bud at that time. Extensive cell death also occurs in the tail bud of embryos homozygous for the vestigial tail mutation, in which there is a marked reduction in Wnt-3a expression. These embryos go on to develop multiple neural tubes in their truncated caudal region. These results suggest that retinoic acid induces down-regulation of Wnt-3a which may play an important role in the pathogenesis of axial truncation, involving induction of widespread apoptosis, followed by an alteration of tail bud cell fate to form multiple ectopic neural tubes.

Cytomegalovirus infection of the nasopharynx.

This report describes a case of cytomegalovirus (CMV) infection of the nasopharynx. A 47 year old man presented with a nasopharyngeal mass of one month's duration. The patient had a history of pneumonia one month previously. Sinus computed tomography incidentally picked up a nasopharyngeal mass. The initial biopsy showed lymphoid hyperplasia. Repeated nasopharyngoscopy showed a prominent central nasopharyngeal mass without ulceration. Histology of the nasopharyngeal biopsy revealed several enlarged epithelial cells with characteristic CMV cytopathic changes. An immunohistochemical study, using a monoclonal IgG antibody against a CMV antigen, confirmed CMV infection. The patient's nasopharyngeal mass decreased in size gradually on follow up. To the best of our knowledge, this is the first reported case of CMV infection of the nasopharynx in the English literature. This disease entity should be considered in those patients presenting with nasopharyngeal mass, biopsy negative for malignancy, and no underlying immunosuppression or immunodeficiency.

Polycythaemia in coal miners with chronic lung disease.

The polycythaemic response to hypoxia was studied in 30 ex-coal miners, comprising 14 patients with complicated pneumoconiosis and 16 with chronic non-specific lung disease. A close correlation was found between arterial oxygen saturation and haemoglobin, packed-cell volume, and the red cell mass.

Hodgkin's disease and leukemia.

Four cases of acute leukemia occurring in patients with Hodgkin's disease are described. The literature on the association of these two diseases is reviewed. Acute myeloid or undifferentiated leukemias appear to be, at least in part, a complication affecting long-term survivors of Hodgkin's disease. Reed Sternberg cell leukemia is an unusual form of Hodgkin's disease and may be associated with a poor prognosis. The cytology and cytochemistry of Reed Sternberg cells are briefly discussed.

Depiction of pelvic fractures using 3D volumetric holography: comparison of plain X-ray and CT.

OBJECTIVE: The goal of this study was to demonstrate the feasibility and test the diagnostic performance of a new technology, 3D volumetric holography, for imaging pelvic fractures. The management of pelvic fractures may be complex, and advanced imaging studies such as CT are frequently indicated. Multiplanar CT reformations and 3D renderings provide clinically useful and complementary display of the directly acquired CT data. With the recent availability of volumetric multiple exposure holograms, produced from serial image data, it is now possible to produce true 3D images of the pelvis. In the hologram, one may view the CT data in 3D or as individual planar slices constituting the whole 3D pelvis. The diagnostic performance of the volumetric multiple exposure holograms was tested against routine radiography, CT, and 3D volumetric CT reconstructions. MATERIALS AND METHODS: Routine radiography and CT were performed in 15 patients with suspected pelvic fractures. Volumetric multiple exposure holograms and 3D volumetric CT reconstructions were created from the CT data. Axial and multiplanar reformation CT images were used as the standard for fracture, diastasis, and intraarticular fragment detection. RESULTS: Radiograms detected 39 of 50 of the fractures and diastases and no intraarticular fragments. The 3D CT reconstructions and the holograms viewed as 3D objects alone missed two small fractures of the anterior column and one hip with intraarticular bone fragments. When the volumetric multiple exposure holograms were viewed as a 3D object and as individual planar slices constituting the whole, their results were the same as the standard. CONCLUSION: Volumetric multiple exposure holograms were as sensitive and specific as axial CT and multiplanar reformations in detecting fracture pathology. By containing and making available, from one image, both planar and 3D information, volumetric multiple exposure holograms detected subtle anatomical features that were hidden by overlapping structures in the radiographs and the 3D CT images.

Spiral CT during arterial portography: technique and applications.

Spiral computed tomography during arterial portography (CTAP) combines rapid scanning with selective imaging during the portal phase of enhancement of the liver, resulting in an effective method for evaluation of liver neoplasms prior to partial hepatic resection. Compared with dynamic incremental CTAP, spiral CTAP results in improved quality of three-dimensional and multiplanar reconstructions, facilitating presurgical planning. Accurate volumetric analysis of the tumor can be performed, and subsegmental tumor localization is facilitated by the high levels of hepatic and portal venous enhancement. Additional advantages of spiral CTAP include small reconstruction intervals for improved lesion detection. However, the specificity of spiral CTAP is low because both benign and malignant tumors appear as hypoattenuating perfusion defects. In addition, both focal and geographic nontumorous perfusion defects may be seen more frequently with spiral CTAP than with dynamic CTAP. Knowledge of common diagnostic pitfalls is necessary for accurate interpretation of spiral CTAP images.