Circulation of a community healthcare-associated multiply-resistant meticillin-resistant Staphylococcus aureus lineage in South Yorkshire identified by whole genome sequencing.

BACKGROUND: A cluster of seven cases of skin and wound infections caused by a multiply resistant meticillin-resistant Staphylococcus aureus (MRSA) were detected in a small-town community in South Yorkshire. Initial microbiological investigations showed that all isolates belonged to a spa type observed rarely in England (t1476). AIM: To describe the epidemiology of t1476 MRSA in South Yorkshire. METHODS: Retrospective and prospective case ascertainment was promoted through communication with local microbiology laboratories. Public health investigation included a detailed review of clinical notes for a subset of nine cases. Genomic and phylogenetic analysis was undertaken on t1476 MRSA. FINDINGS: Thirty-two cases of t1476 MRSA infection or colonization were identified between December 2014 and February 2018. Cases were older adults (aged 50-98 years). Healthcare exposures for a subset of nine cases indicated frequent contact with a team of district nurses, with all but one case receiving treatment on the same day as another case prior to their own diagnosis. No cases were admitted to hospital at the time of specimen collection. Despite detailed investigations, no carriers were detected among district nursing staff. A long-term carrier/super-shedder was not found. Phylogenetic analysis indicated that t1476 MRSA cases from South Yorkshire were monophyletic and distant from both MRSA of the same lineage from elsewhere in the UK (N = 15) and from publicly available sequences from Tanzania. CONCLUSION: Genomic and epidemiological analyses indicate community-based transmission of a multiply resistant MRSA clone within South Yorkshire introduced around 2012-2013, prior to the detection of a spatial-temporal cluster associated with a distinct risk group. Surveillance data indicate continued circulation.

A quantitative morphological study of the bovine vaginal epithelium during the oestrous cycle.

Samples were collected post mortem from 28 cycling parous cows. At all stages of the oestrous cycle, the cranial vaginal epithelium was thinner (P less than 0.001), had fewer cell layers (P less than 0.001) and proportionally more superficial columnar cells (P less than 0.001) than more caudal regions. At all stages of the cycle there were more intraepithelial lymphocytes caudally than in more cranial regions (P less than 0.001). At oestrus the proportion of superficial columnar cells was maximal, having increased from the late dioestrus proportions of 1, 29 and 40 per cent of all superficial cells to 15, 54 and 83 per cent in caudal, middle and cranial regions, respectively (P less than 0.02). However, the epithelial thickness in all regions of the vagina was greatest at metoestrus (P less than 0.02). At this stage, the number of cell layers was greater than at any other stage (P less than 0.05).

The distribution of mucosal lymphoid nodules in the equine respiratory tract.

Mucosal lymphoid nodules were identified within the equine respiratory tract by an acetic acid fixation technique. Nodules were identified in foetuses from nine months gestational age, and estimates of total and regional nodule populations were made in foetal, neonatal and adult horses. Nodules occurred at specific sites within the tract, which probably relate to areas where inhaled antigens accumulate. The largest populations of nodules occurred in the nasopharynx and larynx, with smaller numbers in the nasal cavity, trachea and bronchi. There was an age-related change in the size of these nodule populations, with an increase in number from late gestation to the neonatal period to early adulthood (up to 5 years of age), followed by a decrease in older adults.

A quantitative morphological examination of bovine vulval skin glands.

In adult cows the volumes of sweat and sebaceous glands per unit skin surface area (ssa) in the vulva were greater (P less than 0.01) than in the neck, lip or eyelids. Within this perineal region skin gland volumes were greater dorsally than ventrally (P less than 0.01). Adult cows had much greater (P less than 0.01) volumes of perineal skin glands per unit ssa than 8 weeks or 6 weeks old heifer calves or steers. There was little or no difference between animal categories in neck skin gland dimensions. Adult morphology of perineal sebaceous glands was present in 15 and 18 months but not 6 and 9 months old heifer calves. The skin glands of the perineal region in cows should be considered as specialised skin glands.

Amount and distribution of vestibular-associated lymphoid tissue in calves and adult cows.

Normal reproductive tracts were obtained from 11 adult cows, five eight-week-old and five six-week-old heifer calves. Lymphoid nodules and aggregations (loci) were localised in vestibules by immersion in 2 per cent acetic acid. Adults had significantly more loci (P less than 0.001) than eight- or six-week-old calves, there being means of 194.6, 44.2 and 7.4 loci per vestibule, respectively. In all age groups there was a greater concentration (number cm-2) of loci along the median ventral groove than the side walls (P less than 0.001), and in the caudal third of the vestibule than in the middle or cranial thirds (P less than 0.001). The concentrations of loci were the same in adults and eight-week-old calves but significantly lower in six-week-old calves (P less than 0.01).

The histological features of the immune system of the equine respiratory tract.

The distribution of mucosa-associated lymphoid tissue along the equine respiratory tract was surveyed in light microscopical sections. Intra-epithelial lymphocytes and similar cells scattered in the lamina propria were identified in all sites from the nasal vestibule to bronchioles of 2 to 4 mm diameter. Isolated lymphoid patches, occasionally with nodules, were common in bronchioles, but the density of this bronchiole-associated lymphoid tissue (BRALT) varied between individual horses. Bronchus-associated lymphoid tissue (BALT) was infrequently encountered. In the upper respiratory tract, nodules dispersed within the nasal cavity, nasopharynx and near the auditory tube merit the collective term, nasal-associated lymphoid tissue (NALT). Laryngeal- and tracheal-associated lymphoid tissue (LTALT) was also identified, but this was limited to the epiglottis, arytenoid and rostral trachea. At all sites, the discrete lymphoid masses comprise primary or secondary nodules, a parafollicular and a dome area. The airway lining above was frequently modified into a lympho-epithelium and also showed varied patterns of infolding which might enhance antigen trapping.

Mast cell leukaemia: evidence for bone marrow origin of the pathological clone.

A 57-year-old female patient, admitted for an acute abdominal syndrome, was found to have an extensive proliferation of mast cells both in the peripheral blood and the bone marrow. Cytochemical studies confirmed the mast cell characteristics of the pathological cell population, while the immunophenotype strongly suggested a bone marrow origin of this malignancy. The course of the disease was not affected by antiproliferative treatment and the patient, after progressive general deterioration, died of intractable haemorrhage. On both clinical and haematological criteria it seems possible to distinguish this rare case of primary mast leukaemia from the more common form of tissue mastocytosis with secondary leukaemia.

Erythroid colony formation in primary thrombocythaemia: evidence of hypersensitivity to erythropoietin.

In a group of 14 patients with primary thrombocythaemia (PT) the study of erythropoietic colony formation in vitro showed the development of so-called 'endogenous' colonies, namely colonies with no added erythropoietin (Ep), in all but one case. In the presence of added Ep the colony formation increased slightly in the PT group, but the rise in the control group was so pronounced that any statistical difference between the two groups disappeared. No 'endogenous' colonies were observed in cases of secondary thrombocytosis. This finding reinforces the view that PT is a myeloproliferative disorder and establishes that some erythroid progenitors show the same high sensitivity to Ep as that found in polycythaemia vera; it is of interest that, in the patients studied, there was no apparent involvement of erythropoiesis.

Peripheral blood lymphocyte subpopulations in polycythaemia and thrombocythaemia.

Lymphocyte subpopulations from peripheral blood of normal subjects and patients with primary proliferative polycythaemia (PPP), idiopathic erythrocytosis (IE) and essential thrombocythaemia (ET) were separated using antihuman immunoglobulin antiserum for B lymphocytes and the following monoclonal antibodies: OKT3, directed against the general T-lymphocyte subpopulation, OKT4 and OKT8, detecting respectively T-helper and T-suppressor lymphocyte subpopulations, OKM1 reacting mainly with monocytes. A decrease in the number of OKT3+ cells was observed both in PPP and IE, with a particular fall of the OKT8+ (suppressor) cells, so that the T4/T8 ratio was significantly increased (P less than 0.03 in PPP and P less than 0.0005 in IE). The ratio remained normal in samples from ET. OKM1+ cells were significantly increased in PPP (P less than 0.04), but not in IE, while in ET there was a rise in a few cases only. The present data point out some definite changes in the circulating lymphomonocytic cell subsets, which may be of interest in the study of this group of myeloproliferative disorders.

Haemopoietic patterns of acute leukaemia in remission: CFU-E and CFU-GM colony formation.

Colony formation in vitro from bone marrow haemopoietic progenitors was studied in a group of patients with acute myeloblastic leukaemia and acute lymphoblastic leukaemia at presentation of the disease and, in a few cases, during complete remission. Both granulocytic-macrophagic (CFU-GM) and erythropoietic (CFU-E) colonies were studied. A sharp contrast was observed between CFU-GM and CFU-E formation at presentation of the disease: while the former was markedly depressed, with considerable increase of the cluster colony ratio, CFU-E production was not significantly affected, with only a reduced sensitivity to low-dose erythropoietin. CFU-GM formation returned to normal in the early stages of complete remission, but showed a progressive decline in the course of time; the process of cell differentiation was not significantly impaired, although minor changes were observed. It appears that the leukaemic process has much greater impact altogether on CFU-GM than on CFU-E colony formation, the latter being only marginally affected, even in the presence of a high proportion of blast cells.

Erythroid colony formation in primary proliferative polycythaemia, idiopathic erythrocytosis and secondary polycythaemia: sensitivity to erythropoietic stimulating factors.

This is a study of in vitro production of erythropoietic colonies from peripheral blood and bone marrow of normal subjects and patients with different polycythaemic conditions. Proliferative stimuli included: 1. Fetal calf serum (FCS) only. 2. FCS plus a source of erythropoietic-stimulating activity (ESA). 3. FCS + ESA + erythropoietin (Ep). It was found that normal subjects and patients with secondary polycythaemia (SP) exhibited full colony growth only in the presence of both ESA and Ep, while patients with primary proliferative polycythaemia (PPP) showed colony production with FCS alone, further enhanced in the presence of ESA and Ep. A group of patients with idiopathic erythrocytosis (IE), namely with an increase of red cell mass not accompanied by other signs of myeloproliferative disorder, and without underlying cause, showed a heterogeneous response to ESA which in some patients was significantly greater than in normal subjects or in SP patients. It appears therefore that sensitivity of erythropoietic colony formation to Ep and ESA may be helpful in differentiating among various forms of polycythaemia; this study also establishes the heterogenicity of the IE group.

Potentiation of melphalan activity against a murine tumour by nitroimidazole compounds.

The activity against murine anaplastic MT tumours of the chemotherapeutic agent melphalan, either alone or in combination with one of 6 nitroimidazole compounds, was assayed using an in vivo-in vitro tumour excision assay. The melphalan alone proved cytotoxic to the tumour, whereas relatively little cytotoxicity was produced by any of the nitroimidazoles alone. When the nitroimidazole were given in combination with melphalan, dose-modifying potentiation of its cytotoxicity was observed. Maximum potentiation occurred when the nitroimidazoles were given 0--30 min before the melphalan, although some potentiation was still evident when they were given up to 2 h before or after. There was no threshold in nitroimidazole dose required to produce this potentiation, the degree of potentiation increasing with dose, albeit at a diminishing rate, to give maximum dose-modification factors of about 3. The 6 nitroimidazole compounds in order of increasing effectiveness as potentiators of melphalan activity were: METRO, Ro 05-9963, MISO, RSU 1047, Ro 03-8800 and Ro 03-8799. This order corresponds to the increasing electron affinity of these compounds. The most effective compound here, Ro 03-8799, was about twice as effective as the most widely used nitroimidazole in such studies, MISO.

Potentiation in vivo of melphalan activity by nitroimidazole compounds.

Many nitroimidazole compounds have been shown to potentiate the activity of melphalan against the murine anaplastic MT tumor. The degree of potentiation achieved by these compounds probably depends on their octanol-water partition coefficient and electron affinity: for the greater the partition coefficient of electron affinity, the greater the potentiation. The mechanism of this potentiation remains uncertain. However, it is not due to either nitroimidazole-induced hypothermia, or to the elimination of the recovery from melphalan-induced potentially lethal damage (PLD).