[Epidemic of respiratory tract infections by Mycoplasma pneumoniae in an institute for mentally disabled, investigated with polymerase chain reaction of a throat swab specimen]. / Epidemie van luchtweginfecties door Mycoplasma pneumoniae in een instelling voor verstandelijk gehandicapten onderzocht met polymerasekettingreactie op keeluitstrijk.

OBJECTIVE: To determine the spread of respiratory infection with Mycoplasma pneumoniae in an institute for mentally disabled persons. DESIGN: Descriptive. METHODS: In the period from mid-April to mid-September in a certain year the transmission of M. pneumoniae in the facility was evaluated using questionnaires and laboratory investigations. The laboratory investigations consisted of an M. pneumoniae specific polymerase chain reaction (PCR) on throat swab specimens and detection of antibodies in serum. RESULTS: 21 Residents and 26 staff members from 2/36 units were involved in the initial investigation. 17 Persons had complaints of a (recent) respiratory infection (cough, malaise and fever). In 9 cases an M. pneumoniae infection was confirmed, in 5 cases by PCR and in 4 cases by serology. Two PCR positive persons had only complaints of coughing. During the investigation period 2 more persons were diagnosed with a respiratory infection due to M. pneumoniae. No new cases were found by investigation of contacts outside the facility. CONCLUSION: M. pneumoniae can cause an outbreak of M. pneumoniae respiratory infection in an institute for mentally disabled persons. Rapid detection of this pathogen is possible by PCR and is important for proper antibiotic therapy and epidemic-control measures.

Small intestinal myoelectric activity in healthy neonatal piglets: effects of hyperosmolal formula.

We evaluated 17 healthy neonatal piglets to determine the effects of an increased hyperosmolal formula (HOF; 874 +/- 30 mOsmol/kg, n = 9) and commercial pig milk formula (CF; 482 +/- 35 mOsmol/kg, n = 8) on small intestinal myoelectric activity (SIMEA). Four bipolar electrodes were surgically implanted along the small intestine to evaluate myoelectrical parameters and patterns of SIMEA during fasting and postprandial periods. Durations of myoelectric phase activity and migrating motility complex periodicity were unaffected by both formulas. Differences in SIMEA were not significant when CF and HOF were compared. Following a single meal of increased HOF, piglets demonstrated a significant postprandial increase of phase 2 myoelectric activity in the duodenum through ileum (p less than 0.05) and time-dependent decrease of phase 3 activity in the duodenum (p less than 0.05) and jejunum through terminal ileum (p less than 0.01). Diminished phase 3 activity in the terminal ileum persisted throughout the 4-h postprandial period (p less than 0.01) and was related to fewer phase 3 episodes in this region (p less than 0.05). This pattern of myoelectric activity has been associated with decreased intestinal propulsion and clearing of intraluminal contents. We conclude that a single meal of HOF does not result in significant intestinal motor dysfunction in healthy neonatal piglets. It remains to be determined whether postprandial reductions of phase 3 myoelectric activity that follow a hyperosmolal meal serve as a precursor to neonatal necrotizing enterocolitis when additional risk factors exist.

Hyperosmolal formula in neonatal piglets: effects on gastrointestinal hormone concentrations, enteric bacterial titers, and small intestinal histology.

Ingestion of hyperosmolal formula (HOF) by neonatal piglets has been shown to cause significant time-dependent reduction in phase 3 myoelectric activity, which persists in the terminal ileum. To determine whether a single hyperosmolal meal leads to elevated concentrations of gastrointestinal (GI) hormones that inhibit intestinal motility and/or promote bacterial proliferation and disruption of intestinal mucosa, we studied 20 healthy neonatal piglets following feeding with an increased HOF (872 +/- 32 mOsmol/kg, n = 10) and commercial pig milk formula (481 +/- 41 mOsmol/kg, n = 10). Gastrin, secretin, cholecystokinin, and motilin concentrations were determined by radioimmunoassay during fasting and postprandial periods (15, 30, 45, 120, 180, and 240 min). Gastrin concentrations were significantly increased at 15 and 30 min following a hyperosmolal meal (p less than 0.01), but there were no statistical differences in GI hormone concentrations between groups. These transient elevations of gastrin concentrations are associated with significant postprandial reductions in phase 3 small intestinal myoelectric activity (SIMEA) that we have observed. Aerobic bacterial titers were not significantly different between proximal and distal small intestinal segments or between experimental groups, and anaerobic bacteria were seldom recovered. Thus, SIMEA was not sufficiently altered to produce significant bacterial proliferation. Small intestinal histology, assessed by light microscopy, showed normal proximal and distal small intestinal mucosa in 8 of 10 piglets from each group. Therefore, orogastric instillation of a single hyperosmolal feed does not result in intestinal mucosal damage. Further studies are warranted to determine the effects of hyperosmolal feeds when additional risk factors exist in the neonate.

Influence of repeated upper airway obstruction on the arousal and cardiopulmonary response to upper airway obstruction in lambs.

Experiments were done on five lambs to determine if repeated obstruction of the upper airway influences the arousal and cardiopulmonary response to upper airway obstruction. Each lamb was anesthetized and instrumented for recordings of electrocorticogram, electrooculogram, nuchal and diaphragm electromyograms, and measurements of arterial blood pressure and arterial hemoglobin oxygen saturation. A tracheostomy was done and a fenestrated tracheostomy tube placed in the trachea. The animals were studied after a 3-day recovery period. During a study, a 5F balloon-tipped catheter was inserted into the tracheostomy tube so that air flow could be obstructed by inflating the balloon. The balloon was inflated each time the animal went to sleep for approximately 100 consecutive epochs (17 to 30 h) and the time to arousal and the arterial hemoglobin oxygen saturation at arousal were recorded. Upper airway obstruction was terminated by deflating the balloon once the animal aroused from sleep. Arousal occurred from both sleep states during upper airway obstruction but was delayed in active sleep compared to quiet sleep. The time to arousal and the decrease in arterial hemoglobin oxygen saturation were significantly increased with repeated upper airway obstruction only during active sleep. Inasmuch as it is possible that alterations in the arousal response to respiratory stimuli play a role in sudden infant death, studies to investigate the mechanisms of the state-specific changes in the arousal response to upper airway obstruction are warranted.

Sonographic detection of neonatal umbilical-artery thrombosis: clinical correlation.

Eighty-one neonates were prospectively studied by sonography of the abdomen to determine the frequency, risk factors, clinical symptoms, complications, and natural history of aortic thrombosis seen in conjunction with the use of umbilical-artery catheters. Twenty-six percent of neonates developed sonographically detectable thrombosis. Twenty-nine percent of the neonates with thrombosis were asymptomatic, and an additional 24% had hematuria (diagnosed by dipstick) as their only clinical finding. Significant risk factors associated with aortic thrombosis were calcium in the umbilical-artery-catheter infusate, placement of the catheter for any length of time above the renal arteries, and low birth weight. Physical examination did not reliably predict aortic thrombosis, and asymptomatic thrombosis was more frequent than previously recognized.

Postprandial gastrointestinal blood flow and oxygen consumption: effects of hypoxemia in neonatal piglets.

The effects of feeding on gastrointestinal (GI) perfusion and oxygen transport in hypoxemic neonates is unknown. We evaluated these effects in unanesthetized, spontaneously breathing newborn piglets by comparing three experimental groups: nine hypoxemic piglets (mean PaO2 26 torr) which were fed with formula, six hypoxemic piglets (mean PaO2 27 torr) which were not fed, and four normoxemic piglets (mean PaO2 79 torr) which were fed and served as controls. The control-fed group exhibited an increase in stomach and small intestinal mucosal-submucosal blood flow within 30 min following feeding which was significantly greater than that observed in the hypoxemic fed piglets. GI O2 delivery and O2 uptake rose significantly (p less than 0.05) following a meal secondary to increases in total GI blood flow. Oxygen extraction was unchanged postprandially in the control group. In the hypoxemic nonfed piglets, total and regional GI blood flow was unaltered during hypoxemia. Reductions in arterial O2 content led to significant decreases in GI O2 delivery. Gastrointestinal oxygen uptake remained stable with a compensatory increase in GI O2 extraction. In the hypoxemic-fed piglets, hypoxia significantly decreased stomach blood flow and led to unchanged blood flow in the remainder of the GI tract. Significant reductions in arterial O2 content and GI O2 delivery were observed, accompanied by significant increases in O2 extraction. Hypoxemic fed animals did not exhibit the expected increase in O2 uptake to meet postprandial metabolic demands. When the hypoxemic insult was terminated, fed piglets demonstrated significant total and regional GI hyperemia leading to increased GI O2 uptake when compared with hypoxemic nonfed piglets.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of non-nutritive and nutritive suck on gastric emptying in premature infants.

Ten healthy preterm infants were studied to determine if non-nutritive and nutritive suck significantly altered gastric emptying patterns when compared with gavage feeding alone. We used a 10% dextrose meal with phenol red marker and a double sampling technique to determine gastric emptying at 10-min intervals over a 30-min test period. A crossover study design compared the effects of the three feeding methods in each infant. The gastric residual volumes expressed in milliliters per kilogram did not differ significantly when comparisons were made among groups at 10, 20, and 30 min following the test meal. Non-nutritive suck and nutritive suck and swallow of a liquid dextrose meal do not significantly improve gastric emptying in healthy preterm infants. The beneficial effects of non-nutritive and nutritive sucking on the nutritional status of preterm infants, demonstrated by others, are not related to improved gastric evacuation of feeds. Alternative explanations for these beneficial effects require further investigation.

Effects of hypoxemia on gastrointestinal blood flow and gastric emptying in the newborn piglet.

The effects of severe hypoxemia on gastrointestinal (GI) blood flow and gastric emptying were studied in nine 2- to 4-day-old piglets which were mechanically ventilated while receiving nitrous oxide anesthesia. Each animal was studied during a control period of oxygenation (PaO2 91 +/- 8 torr), 35 min of hypoxemia (PaO2 29 +/- 1 torr), and a recovery period (PaO2 90 +/- 5 torr) (mean +/- SEM). During each study period, the animal received a 10% dextrose test meal with phenol red marker (22 ml/kg), gastric residual volumes were determined at 10-min intervals over 30-min study periods using a dye dilution double sampling technique, and GI blood flow (radionuclide-labeled microspheres), O2 delivery, O2 extraction, and O2 consumption were measured at the end of the 30-min period. Hypoxemia resulted in decreased blood flow to the following GI organs: stomach, jejunal and ileal mucosa-submucosa, and colon decreased 62, 31, and 35%, respectively (p less than 0.05). Jejunal and ileal muscularis blood flow remained unchanged. Oxygen delivery and consumption by GI tract decreased 79 and 58%, respectively; whereas oxygen extraction of GI tract increased 115%. Values returned toward baseline levels during the recovery period. The hypoxemic gastric emptying pattern showed significantly greater gastric residuals at 20 min compared to the 10-min value (p less than 0.05). This pattern was different than that observed during control and recovery periods. We conclude that severe hypoxemia results in decreased GI blood flow, tissue oxygenation, and an altered gastric emptying pattern. These observations may have clinical significance for feeding infants following an hypoxemic episode.