Investigation of an outbreak of methicillin-resistant Staphylococcus aureus in patients with skin disease using DNA restriction patterns

OBJECTIVE

To investigate an outbreak of methicillin-resistant Staphylococcus aureus (MRSA) among patients using chromosomal typing of the isolates.

DESIGN

Comparison of epidemiological and clinical data to endonuclease restriction fragmentation analysis (RFA) of the MRSA isolates associated with an outbreak. Total DNA from the MRSA isolates was restricted with HINDIII and HAEIII for typing.

SETTING

Tertiary care academic medical center.

METHODS

An epidemiological investigation of an outbreak of MRSA among patients in private rooms was evaluated by routine infection control methods. The MRSA isolates from blood cultures of 7 patients and the nares of a nurse were collected during the outbreak. MRSA isolates from 23 patients not associated with the outbreak also were collected. The total DNA of the MRSA isolates were restricted with HINDIII and HAEIII and electrophoresed on 0.6% agarose gels.

RESULTS

MRSA from 4 of the 7 bacteremic patients and the nurse on the outbreak unit had the same endonuclease restriction pattern. The patients were linked in that they were compromised by severe psoriasis or skin ulcers, were on the unit during the same period, and had oatmeal baths in a common bathtub. Of 50 staff members screened, the nurse was the only person detected as colonized by the strain. The other 3 patients on the unit as well as the 23 patients in other locations not associated with the outbreak had MRSA isolates with different RFA patterns. The use of the bathtub was discontinued and further transmission of MRSA was stopped.

CONCLUSIONS

A comparison of the relatedness of MRSA by RFA demonstrated the uniqueness of the epidemiologically linked isolates and the utility of the RFA technique in the performance of routine infection control investigations.

Effect of ischemia and reperfusion on lambda of the lumped constant of the [14C]deoxyglucose technique

We measured the parameter lambda, which is the ratio of the distribution spaces of 2-deoxy-D-glucose (DG) and glucose in the brain, in a model of focal cerebral ischemia in the cat. lambda is the parameter in the lumped constant of the [14C]DG technique most susceptible to changes in ischemia. Cats were subjected to occlusion of the middle cerebral artery for a period of 2 h. During the last 60 min of occlusion, [14C]DG was infused in a programmed fashion so as to obtain a stable arterial blood [14C]DG concentration. The brain was funnel-frozen to preserve tissue metabolites and the frozen brain was sampled regionally (4 to 7-mg samples) for local concentrations of glucose, ATP, phosphocreatine (PCr), and lactate. In a separate series of cats, the infusion of [14C]DG was started after 2 h of occlusion and 3 h of recirculation. In both series, lambda declined slightly for increased levels of tissue glucose and increased appreciably as tissue glucose decreased. A similar relationship was observed between lambda and ATP and PCr, although the correlation was not as clear. Since lambda, and hence the lumped constant, increases in ischemia as well as in postischemic tissue, it is important to measure tissue glucose concentration if quantitative values of local cerebral glucose metabolism are desired in this condition.

The aesthetic alliance: nurses and medical facials

This article introduces and explains methods for integrating services of dermatology nurses and cosmetic dermatologists. Basic aesthetic techniques can be incorporated into the dermatology practice; or a specialist, namely a licensed aesthetician, can perform the medical facial.

Amylin secretion from the rat pancreas and its selective loss after streptozotocin treatment

Amylin, a peptide copackaged with insulin in beta-cell granules, was measured in the effluent of the perfused rat pancreases by means of a newly developed specific radioimmunoassay. Its secretion parallels that of insulin in response to 20 mM glucose, 10 mM arginine, or the combination thereof. The relative molar amount of secreted amylin was estimated to be 25-37% that of insulin. Treatment with a borderline diabetogenic dose of streptozotocin reduced amylin response without significantly changing the insulin response. A severely diabetogenic dose of streptozotocin totally abolished amylin release and markedly reduced insulin release. The selective impairment of amylin secretion in streptozotocin-treated rats could represent an early manifestation of beta-cell depletion or injury.

gamma-Aminobutyric acid inhibits the potassium-stimulated release of somatostatin from rat spinal cord slices

Evidence supports the idea that somatostatin (SO) is a neurotransmitter or neuromodulator of primary afferent neurons involved in nociception. Since gamma-aminobutyric acid (GABA), norepinephrine, and morphine alter nociception at the level of the spinal cord, we examined whether these agents could alter the potassium-stimulated release of somatostatin from rat spinal cord slices. Male Sprague-Dawley rats were decapitated and a 2 cm segment of the lumbar spinal cord removed and chopped into 0.5 x 0.5 mm pieces and perfused at 37 degrees C in individual perfusion chambers with a modified Krebs-bicarbonate buffer at a flow rate of 0.5 ml/min. Perfusates were collected at 2 min intervals and assayed for SO using radioimmunoassay. Exposure of spinal cord tissue to 50 mM KCl resulted in a 3-fold increase in release of SO from a basal level of approximately 0.2 to 0.6 pg/mg tissue/min. This evoked release was calcium dependent. Pre-exposure of tissue to GABA at 10(-4) and 10(-5) M significantly inhibited the potassium-stimulated release of SO, but did not alter basal release. The GABA receptor antagonist, bicuculline methiodide, at 10(-5) but not 10(-6) M attenuated the GABA-induced inhibition of somatostatin release. Bicuculline methiodide alone did not significantly alter either basal or stimulated release. Neither baclofen (10(-5) M, 5 x 10(-5) M), norepinephrine (10(-5) M), nor morphine (10(-5) M) had any significant effect on basal or stimulated release of SO from spinal cord tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Duodenal ulcer in sickle cell anemia

A 14-year-old black male with sickle cell anemia developed a duodenal ulcer that masqueraded as sickle cell-related abdominal pain crisis on multiple occasions. Malingering and poor therapeutic compliance aggravated the ulcer in this patient, who ultimately succumbed to a catastrophic bleed. Duodenal ulcer appears to be an infrequent but difficult to treat lesion in sickle cell disease. An in-depth review on the occurrence of duodenal ulcer in sickle cell anemia is presented. The etiological mechanisms of peptic ulcer disease in this population and the potential benefits of transfusion therapy are discussed.

Neural defects in Jarcho-Levin syndrome

Neuropathologic examination of two autopsied patients with Jarcho-Levin syndrome showed no pathologic changes in the brain, spinal cord, or nerve roots of one and diastematomyelia of the thoracolumbar spinal cord in the other. The abnormalities of the spinal cord in one of our patients and in another patient described in the literature establish neural defects as a component of the Jarcho-Levin syndrome.

Cervical esophageal duplication cyst: MR imaging

Magnetic resonance (MR) imaging was performed in the evaluation of a cervical esophageal duplication cyst in a 9-month-old infant. The value of MR in the assessment of the origin of this cystic lesion as well as the nature of its contents is discussed.

Sonographic renal parameters as related to age

Four hundred and fifty-four kidneys were evaluated by real time ultrasound for appearance of renal cortical echogenecity, medullary pyramids and central sinus echoes. These renal parameters were correlated with age in 227 patients ranging in age from 0-15 years. The renal parenchymal echogenicity was observed to change not abruptly at a certain age but gradually over a period of years.

Secretory patterns of glucoregulatory hormones in prehepatic circulation of dogs

The temporal organization of patterns of secretion of insulin, glucagon, and somatostatin was studied in basal conditions in normal or pancreatectomized dogs fitted with an indwelling hepatic portal catheter. Portal and peripheral blood samples were collected at a 7.5- or 15-min frequency, which covered the medium range of the ultradian period. The raw data were studied using spectral analyses employing fast Fourier transformation (FFT) techniques. The results indicate that in normal dogs: 1) endogenous physiological periodicities, statistically significant at a level of alpha = 0.05 (i.e., 95% confidence interval), were found to exist for the three pancreatic hormones in portal blood between 0.54 and 1.78 h/cycle and in peripheral blood between 0.59 and 1.84 h/cycle; 2) the portal levels of the hormones are significantly higher than peripheral ones; and, 3) whereas pancreatic hormones oscillated, glucose was found to maintain a steady level. In pancreatectomized dogs, no regular rhythm was detected. Thus, whereas endogenous periodicities exist for the secretion of pancreatic hormones in the normal dog, in the pancreatectomized dog the extrapancreatic glucagon and somatostatin are secreted in nonperiodic, randomly occurring pulses.

Hylambatin, a structurally unique tachykinin: effects on insulin and glucagon secretion

Hylambatin is the first example of a tachykinin which possesses a methionyl methionine residue at the C-terminus, rather than the C-terminal tripeptide -Gly-Leu-Met-NH2 which hitherto has been a characteristic feature of all members of the tachykinin family. The effect of hylambatin on the secretion of glucoregulatory hormones was examined in the rat. Hylambatin, injected intravenously in graded doses 10 and 30 min before blood collection, significantly increased both plasma glucose and plasma insulin, whereas the secretion of glucagon was not affected. This profile of action is different from that of kassinin or substance P. Should hylambatin, like other neuropeptides, be present in mammalian tissue, it may have a role in the regulation of carbohydrate metabolism.

Rapid changes in hepatic glucose output after a pulse of growth hormone in dogs

In response to a single intravenous injection of bovine growth hormone (GH, 100 micrograms/kg) the non-steady-state turnover of glucose, as well as portal levels of insulin (IRI), glucagon (IRG), somatostatin (SRIF), and glucose were determined in normal conscious dogs. Using the two-compartment model validated to calculate rapid turnover changes and tracer infusion methods, the rate of hepatic output of glucose [Ra(t)] was found to be increased, reaching a maximum of 224 mg/min, 7.4 times the basal rate, 4 min after injection of GH. Ra(t) returned to its basal level 35 min later in a damped oscillatory manner. Hormone determinations were carried out in portal venous blood drawn every 2 min for 2 h from an indwelling catheter. IRG peaked 2 min after GH injection and levels of IRI, SRIF, and glucose peaked between 4 and 8 min. Hormone concentrations returned to normal, i.e., were oscillating around base-line levels, about 30 min after GH. These experiments demonstrate for the first time in vivo that a pulse of GH causes transient changes of glucose turnover and measurable alterations of the hormonal homeostasis in the splanchnic area.

Dermorphin: an opioid peptide from amphibian skin which affects endocrine pancreatic function

We examined the effect of intravenous injection of the amphibian skin opioid heptapeptide dermorphin on plasma glucose, insulin, glucagon and somatostatin in the rat. Dermorphin in doses ranging from 0.1 to 10 micrograms per animal did not affect plasma insulin or somatostatin-like immunoreactivity (SLI). In contrast, the opiate peptide significantly stimulated plasma glucagon and decreased plasma glucose, both 10 and 30 min following injection. The results suggest an effect of dermorphin on the endocrine pancreas. Since dermorphin has been shown to be present in rat and porcine tissues, it may have a role in the regulation of glucose metabolism.

Extraction of somatostatin from human plasma on octadecylsilyl silica

Human plasma contains substances that interfere with the radioimmunoassay (RIA) of somatostatin-like immunoreactivity (SLI). A method has been developed for rapid, reproducible extraction of somatostatin from human plasma on octadecylsilylsilica (ODS). Hydrophobic binding of somatostatin to ODS permitted extraction of the peptide from untreated human plasma, elution of less tightly bound substances with dilute acid, and then elution of somatostatin by 80:20 acetonitrile:0.1% trifluoroacetic acid. The lyophilized extract was reconstituted to a volume of 0.5 ml prior to quantification by RIA. This 6-fold concentration resulted in an effective lower limit of detection of 7.5 pg/ml of plasma. The interassay coefficient of variation for the combined extraction and RIA was 20% (n = 10) at a mean plasma level of 15 pg/ml. Basal concentrations of somatostatin in human plasma ranged from 8 to 20 pg/ml (n = 35, mean - 13.3 +/- 0.4). Basal somatostatin levels (mean = 14.0 +/- 0.4 pg/ml) for nonobese (BMI less than 30, n = 10) were not different from values (mean = 13.3 +/- 0.7 pg/ml) observed for the obese group (BMI greater than 35, n = 17) nor from the values (n = 8, x = 15.4 +/- 1.2 pg/ml) obtained for subjects with non-insulin dependent diabetes mellitus.

Kassinin: stimulation of insulin and glucagon secretion in the rat

The effect of the newly discovered tachykinin dodecapeptide kassinin on endocrine pancreatic function was examined in the rat and compared to that of substance P, a neuropeptide which is structurally closely related to kassinin. Kassinin, injected iv in graded doses 10, 20, and 30 min before blood collection, significantly increased both plasma insulin and plasma glucagon in a dose-related fashion. The largest dose examined (10 micrograms) increased plasma insulin by 275% and plasma glucagon by 77%. In contrast, iv injections of equimolar doses of substance P did not affect either hormone. However, both kassinin and substance P increased plasma glucose levels in a dose-dependent fashion. Kassinin appears to have biological actions on the endocrine pancreas which clearly can be distinguished from those of substance P. Should kassinin be present in mammalian tissue and show a distribution similar to that of other neuropeptides, it may play a role in the physiological regulation of carbohydrate metabolism.

Role of H2-receptors in gastrogenic hyperglycemia and hyperinsulinemia in dogs

Recent studies have demonstrated that an acidified liver meal stimulates insulin release and raises plasma glucose levels. To examine the mechanism of these changes, a liver extract test meal at either pH 7 or at pH 2 was instilled into the stomach of dogs with a bisected pylorus and a gastric fistula during the infusion of either cimetidine, a specific H2-receptor antagonist, or a saline control. In response to the meal at pH 2 insulin, glucagon and glucose levels rose significantly and were not significantly changed by the infusion of cimetidine. In response to the liver meal at pH 7 a late rise in plasma glucagon levels was observed while plasma insulin and glucose did not change significantly; however, during the infusion of cimetidine a significant rise in plasma insulin and glucose levels occurred. The present data suggest that H2-receptors participate in an inhibitory mechanism with respect to the insulin and glucose response during the gastric phase of a neutral meal, but they do not seem to be involved in the rise in insulin and glucose observed in response to an acidified gastric meal.

Kassinin and substance P stimulate somatostatin release in the rat

1. The effect of the tachykinin dodecapeptide kassinin, which has been extracted from the skin of several African frogs, on somatostatin release was examined in the rat and compared with that of the neuropeptide substance P. 2. Equimolar doses of the two peptides were injected intravenously and the animal killed at specified intervals after injection. Somatostatin was measured by a specific radioimmunoassay. 3. Kassinin and substance P had no effect when given in low doses (0 . 1 and 1 . 0 microgram). However, when administered in a dose of 10 . 0 microgram, both peptides significantly increased plasma somatostatin, by 31 and 22% respectively. 4. These findings suggest that kassinin and substance P have common endocrine actions. The effect of somatostatin release may be specific for tachykinins, since other neuropeptides such as the enkephalins have no effect.

Effect of gastric inhibitory polypeptide on plasma levels of chylomicron triglycerides in dogs

To determine whether gastric inhibitory polypeptide (GIP) promotes the clearance of chylomicron triglycerides (TG) from the circulation in dogs, chyle collected from donor dogs via a thoracic duct fistula was infused at a rate of 2 ml/min i.v. into normal recipient dogs during an infusion of either porcine GIP (1 microgram/kg per h) or saline as a control. In the GIP-infused dogs the rise in plasma TG was significantly below that of the control animals [mean peak of 36 +/- 4 mg/dl vs. 82 +/- 18 mg/dl (P less than 0.05)]. It is concluded that GIP exerts an effect upon the removal of chylomicron TG from the blood. The results suggest that GIP may play a physiologic role in the disposition of ingested fat.

Evidence for the hormonal status of somatostatin in man

To determine the hormonal status of somatostatin in man, plasma levels of approximately 1600-dalton somatostatin-like immunoreactivity (SLI) were measured before and after a mixed meal. Plasma was subjected to gel filtration and the fractions coeluting with somatostatin were concentrated ninefold before radioimmunoassay. In this system the recovery of synthetic somatostatin added to plasma averaged 71 +/- 4.6% (mean +/- SE, N = 5). Synthetic somatostatin infused into normal volunteers gave a dose-related increase in the measured SLI value. Fasting SLI in 13 normal volunteers was 8.0 +/- 0.7 pg/ml (mean +/- SE) and rose to 18.6 +/- 1.5 pg/ml and 20.3 +/- 2.0 pg/ml at 60 and 120 min, respectively, after the meal (P less than 0.001). In seven type I diabetics, the fasting level was 11.5 +/- 1.6 pg/ml and the 60- and 120-min postprandial levels were 21.4 +/- 2.5 and 22.3 +/- 2.9 pg/ml, respectively. The meal-induced rise in approximately 1600 M.W. SLI approximated that produced by infusing somatostatin at 2 microgram/h, a rate that significantly suppressed glucagon levels. These results are therefore consistent with a hormonal role for somatostatin in man.

Origin of peripheral venous hypersomatostatinemia in alloxan-diabetic dogs

Basal and postprandial somatostatin-like immunoreactivity (SLI) is elevated in the peripheral venous plasma of chronic alloxan-diabetic dogs. To determine if this hypersomatostatinemia was the consequence of increased somatostatin release from the pancreas, stomach, or both, plasma SLI was measured in the pancreaticoduodenal, antral, and fundic veins and in the inferior vena cava in response to stimulation by a gastric liver test meal, followed by an intragastric HCl load. Basal and postprandial inferior vena caval plasma SLI levels were significantly higher than the control level (P less than 0.05-0.001), confirming earlier findings. Basal pancreatic venous SLI was 780 +/- 45 pg/ml in the diabetic dogs and 493 +/- 65 pg/ml in the controls (P less than 0.02). In response to the liver meal at pH 7, the incremental pancreatic venous SLI level in the diabetic dogs was 1630 +/- 95 pg/ml, and after HCl it rose to 9479 +/- 384 pg/ml compared to 938 +/- 80 and 4677 +/- 192 pg/ml, respectively, in the controls (P less than 0.02 and P less than 0.005). However, antral and fundic venous SLI levels in the diabetic dogs did not differ from the controls in either basal or stimulated states. The present data demonstrate that the pancreas and not the stomach is the probable source of the peripheral hypersomatostatinemia of alloxan-diabetic dogs.