Pleural fluid nucleic acid testing enhances pneumococcal surveillance in children.

BACKGROUND AND OBJECTIVE: National surveillance of invasive pneumococcal disease (IPD) includes serotyping Streptococcus pneumoniae (SP) isolates from sterile site cultures. PCR is more sensitive and can identify more SP serotypes (STs) in culture-negative samples. The aim of this study was to determine whether enhanced surveillance of childhood empyema, using PCR, provides additional serotype information compared with conventional surveillance. METHODS: Pleural fluid (PF) from children with empyema were cultured and tested by PCR to identify SP, targeting the autolysin gene (lytA). Multiplex PCR-based reverse line blot assay was used to identify SP STs. Corresponding IPD surveillance and serotype data were obtained from the National Notifiable Diseases Surveillance System (NNDSS). RESULTS: Eighty-nine children with empyema, aged ≤16 years, were recruited between April 2008 and March 2009, inclusive. SP was isolated from 5/84 (5.9%) PF cultures and by PCR in 43/79 (54.4%) PF samples. Serotypes were unidentifiable in 15 samples. The frequency of six serotypes (or serotype pairs) identified in 28 samples, including one with two serotypes, were: ST1, n = 4/29 (13.8%); ST3, n = 9/29 (31.0%); ST19A, n = 12/29 (41.4%); ST7F/7A, n = 1/29 (3.4%); ST9V/9A, n = 1/29 (3.4%); ST22F/22A, n = 2/29 (6.9%). Over the same period, 361 IPD patients, aged 16 years or less, were notified to NNDSS. Among 331 serotypeable NNDSS isolates (71.5% from blood), the frequencies of ST1 and 3 were significantly lower than in PF samples: ST1, n = 8/331 (2.4%; P < 0.05); ST3, n = 13/331 (3.9%; P < 0.0001). CONCLUSIONS: The use of PCR to identify and serotype SP in culture-negative specimens provides additive information.

Bacterial causes of empyema in children, Australia, 2007-2009.

An increase in the incidence of empyema worldwide could be related to invasive pneumococcal disease caused by emergent nonvaccine replacement serotypes. To determine bacterial pathogens and pneumococcal serotypes that cause empyema in children in Australia, we conducted a 2-year study of 174 children with empyema. Blood and pleural fluid samples were cultured, and pleural fluid was tested by PCR. Thirty-two (21.0%) of 152 blood and 53 (33.1%) of 160 pleural fluid cultures were positive for bacteria; Streptococcus pneumoniae was the most common organism identified. PCR identified S. pneumoniae in 74 (51.7%) and other bacteria in 19 (13.1%) of 145 pleural fluid specimens. Of 53 samples in which S. pneumoniae serotypes were identified, 2 (3.8%) had vaccine-related and 51 (96.2%) had nonvaccine serotypes; 19A (n = 20; 36.4%), 3 (n = 18; 32.7%), and 1 (n = 8; 14.5%) were the most common. High proportions of nonvaccine serotypes suggest the need to broaden vaccine coverage.

Preliminary evaluation of a new technique of minimally invasive surfactant therapy.

OBJECTIVE: To investigate a method of minimally invasive surfactant therapy (MIST) to be used in spontaneously breathing preterm infants on continuous positive airway pressure (CPAP), evaluating the feasibility of the technique and the therapeutic benefit after MIST. DESIGN: Non-randomised feasibility study. SETTING: Tertiary neonatal intensive care unit. PATIENTS AND INTERVENTIONS: Study subjects were preterm infants with respiratory distress supported with CPAP, with early enrolment of 25-28-week infants (n=11) at any CPAP pressure and fractional inspired O(2) concentration (FiO(2)), and enrolment of 29-34-week infants (n=14) at CPAP pressure ≥7 cm H(2)O and FiO(2) ≥0.35. Without premedication, a 16 gauge vascular catheter was inserted through the vocal cords under direct vision. Porcine surfactant (~100 mg/kg) was then instilled, followed by reinstitution of CPAP. MEASUREMENTS AND RESULTS: Respiratory indices were documented for 4 h following MIST, and neonatal outcomes ascertained. In all cases, surfactant was successfully administered and CPAP re-established. Coughing (32%) and bradycardia (44%) were transiently noted, and 44% received positive pressure inflations. There was a clear surfactant effect, with lower FiO(2) after MIST (pre-MIST: 0.39±0.092 (mean±SD); 4 h: 0.26±0.093; p<0.01), and a modest reduction in CPAP pressure. Adverse outcomes were few: intubation within 72 h (n=3), pneumothorax (n=1), chronic lung disease (n=3) and death (n=1), all in the 25-28-week group. Outcome was otherwise favourable in both gestation groups, with a trend towards reduction in intubation in the first 72 h in the 25-28-week infants compared with historical controls. CONCLUSIONS: Surfactant can be effectively delivered via a vascular catheter, and this method of MIST deserves further investigation.

A bedside assay to detect streptococcus pneumoniae in children with empyema.

BACKGROUND: Empyema is a complication of pneumonia, commonly caused by Streptococcus pneumoniae. AIMS: To validate the utility of an immunochromatographic test for the detection of S. pneumoniae antigen in the pleural fluid of children with empyema. METHODS: Empyema patients had blood and pleural fluid cultured, and polymerase chain reaction (PCR) to detect the S. pneumoniae autolysin gene, lytA, in pleural fluid. Pleural fluid was tested using the Binax NOW S. pneumoniae antigen detection assay and compared with lytA PCR results and/or culture in blood or pleural fluid. RESULTS: S. pneumoniae was detected by PCR in pleural fluid of 68 of 137 (49.6%) patients, by culture in 11 of 135 (8.1%) pleural specimens and 16 of 120 (13.3%) blood specimens. Pleural fluid Binax NOW testing from 130 patients demonstrated a sensitivity of 83.8% and specificity of 93.5% (positive predictive value of 93.4% and negative predictive value of 84.1%). CONCLUSIONS: In pediatric empyema, high predictive values of pleural fluid Binax NOW S. pneumoniae antigen test suggest that this test may help rationalize antibiotic choice in these patients.

Arterial fast bolus flush systems used routinely in neonates and infants cause retrograde embolization of flush solution into the central arterial and cerebral circulation.

PURPOSE: To evaluate the risk of retrograde embolization of flush solution in neonates and infants with routinely used electronic syringe pumps and infusion bag pump flush systems. METHODS: With hospital Ethical Committee approval we studied intubated neonates and infants with a 24-GA radial arterial cannula. Fast flush boluses were delivered from the infusion bag pump flush system by opening the flow regulating device for two seconds at bag pump manometre pressures of 100, 200 and 300 mmHg. In the syringe pump flush system, fast flush bolus volumes of 0.5, 1.0, 1.5 and 2.0 mL were programmed on the electronic syringe pump and released by opening the flow regulating device for two seconds. A 12-MHz ultrasonic probe placed in the jugular fossa was used to detect white bubbles indicating retrograde embolization of flush solution into the ipsilateral subclavian and common carotid artery. RESULTS: Sixteen patients, aged from 1-105 days (median 22 days) were studied. In all patients retrograde embolization into the subclavian artery was detected at syringe pump bolus volumes of 0.5-1.5 mL and at 100-200 mmHg bag pump pressure. In nine of the 16 patients a positive signal was detected in the common carotid artery with 1.5-2.0 mL syringe pump bolus volumes and at 200-300 mmHg bag pump pressure. CONCLUSIONS: In neonates and infants, the standard practice of arterial fast bolus flushing using syringe pump and bag pump flush systems causes retrograde embolization of flush solution into the central arterial and even into the cerebral circulation. The mandatory limitation of fast flush bolus volumes and manometre pressures is urgent in order to reduce retrograde embolization of flush solution and the associated risks in these small patients.

Flush volumes delivered from pressurized bag pump flush systems in neonates and small children.

BACKGROUND: The aim of this study was to measure the volumes of fluid delivered with a fast flush bolus from a flow regulating device. METHODS: In-vitro fast flush bolus volumes, the volumes delivered from a bag pump flush system while opening the flow regulating device for 1, 2 or 5 s, were gravimetrically measured through a 22-G and a 24-G cannula. In-vivo 1- and 2-s fast flush bolus volumes and the volume required to purge the tubing between stopcock and arterial cannula from visible blood after blood sampling were recorded in 12 anaesthetized neonates and infants (mean age 2.17 +/- 1.97 months, range 0.26-5.37 months) with a 24-G radial arterial cannula by continuously weighing the bag pump flush system at manometer pressures of 100, 200 and 300 mmHg. RESULTS: In-vitro fast flush bolus volumes ranged from 0.23 +/- 0.04 ml (1-s, 100 mmHg, 24-G cannula) to 2.95 +/- 0.38 ml (5-s, 300 mmHg, 22-G cannula). Volumes were larger using a 22-G cannula than a 24-G cannula (P < 0.01) and increased with longer flushing periods (P < 0.0001) and higher manometer pressures (P < 0.0001). In-vivo 1- and 2-s fast flush bolus volumes correlated well with driving pressures (infusion pressure minus mean arterial pressure) (r2 = 0.81/0.72). 1-s fast flush bolus volumes delivered (ml) were 0.0025 x mmHg driving pressure and 2-s fast flush bolus volumes delivered (ml) were 0.0043 x mmHg driving pressure. The mean volume delivered to purge blood from the arterial pressure tubing was 0.94 +/- 0.18 ml (range 0.61-1.34 ml). CONCLUSIONS: Fast bolus flushing from pressurized infusion bag systems, using the flow regulating device tested, can be applied during neonatal and paediatric anaesthesia without delivering uncontrolled amounts of fluid.