Acute phase response in the diagnosis of bacterial infections in children

Pilot clinical study of quantitative ultrasound spectroscopy measurements of erythrocyte aggregation within superficial veins

BACKGROUND:

An enhanced inflammatory response is a trigger to the production of blood macromolecules involved in abnormally high levels of erythrocyte aggregation.

OBJECTIVE:

This study aimed at demonstrating for the first time the clinical feasibility of a non-invasive ultrasound-based erythrocyte aggregation quantitative measurement method for potential application in critical care medicine.

METHODS:

Erythrocyte aggregation was evaluated using modeling of the backscatter coefficient with the Structure Factor Size and Attenuation Estimator (SFSAE). SFSAE spectral parameters W (packing factor) and D (mean aggregate diameter) were measured within the antebrachial vein of the forearm and tibial vein of the leg in 50 healthy participants at natural flow and reduced flow controlled by a pressurized bracelet. Blood samples were also collected to measure erythrocyte aggregation ex vivo with an erythroaggregometer (parameter S₁₀).

RESULTS:

W and Din vivo measurements were positively correlated with the ex vivoS₁₀ index for both measurement sites and shear rates (correlations between 0.35–0.81, p < 0.05). Measurement at low shear rate was found to increase the sensitivity and reliability of this non-invasive measurement method.

CONCLUSIONS:

We behold that the SFSAE method presents systemic measures of the erythrocyte aggregation level, since results on upper and lower limbs were highly correlated.

Quantitative Measurement of Erythrocyte Aggregation as a Systemic Inflammatory Marker by Ultrasound Imaging: A Systematic Review

This systematic review is aimed at answering two questions: (i) Is erythrocyte aggregation a useful biomarker in assessing systemic inflammation? (ii) Does quantitative ultrasound imaging provide the non-invasive option to measure erythrocyte aggregation in real time? The search was executed through bibliographic electronic databases CINAHL, EMB Review, EMBASE, MEDLINE, PubMed and the grey literature. The majority of studies correlated elevated erythrocyte aggregation with inflammatory blood markers for several pathologic states. Some studies used "erythrocyte aggregation" as an established marker of systemic inflammation. There were limited but promising articles regarding the use of quantitative ultrasound spectroscopy to monitor erythrocyte aggregation. Similarly, there were limited studies that used other ultrasound techniques to measure systemic inflammation. The quantitative measurement of erythrocyte aggregation has the potential to be a routine clinical marker of inflammation as it can reflect the cumulative inflammatory dynamics in vivo, is relatively simple to measure, is cost-effective and has a rapid turnaround time. Technologies like quantitative ultrasound spectroscopy that can measure erythrocyte aggregation non-invasively and in real time may offer the advantage of continuous monitoring of the inflammation state and, thus, may help in rapid decision making in a critical care setup.

Evidence of Microvascular Changes in the Retina following Kawasaki Disease

It is unclear whether all children with Kawasaki disease (KD) have increased later cardiovascular risk. The retinal microvasculature reflects changes in the microcirculation and is associated with traditional cardiovascular risk factors and events. The aim of this study was to investigate retinal microvascular parameters in two populations of patients with previous KD and control participants. We performed case-control studies of 116 (57 patients and 59 control participants) Australian and 156 (78 patients and 78 control participants) Singaporean individuals, at least two years since their acute illness. Standardised retinal photographs were graded by trained technicians using a semi-automated software, which quantifies the retinal microvasculature (calibre, branching angle, fractal dimensions, and tortuosity). Retinal venules of Singaporean KD patients were 9.67 μm (95% CI 4.87 to 14.51, p < 0.001) larger than control participants following correction for traditional cardiovascular risk factors. An incremental increase in the size of retinal venules in those with coronary artery abnormalities was observed. There was limited evidence that retinal venules were larger in Australian KD patients with coronary artery abnormalities compared to control participants (7.34 μm, 95% CI 1.30 to 15.99, p = 0.10). Differences in retinal microvasculature were particularly evident in Singaporean KD patients. Larger retinal venules may reflect chronic inflammation and endothelial dysfunction, and are associated with coronary artery disease in adults.

C-Reactive Protein As a Marker for Initiating Steroid Treatment in Children With Orbital Cellulitis

PURPOSE

To determine both the benefit of systemic steroids in pediatric patients with orbital cellulitis and to assess the usefulness of C-reactive protein (CRP) levels as a marker for starting steroids.

METHODS

Prospective, comparative interventional study. Pediatric patients aged 1 to 18 years admitted to a tertiary care children's hospital with a diagnosis of orbital cellulitis from October 2012 to March 2014 were included in the study. All patients were treated with intravenous antibiotics, and patients with subperiosteal abscess who met previously published criteria for surgical decompression underwent combined transorbital drainage and/or endoscopic sinus surgery. CRP was measured daily as a biomarker of inflammation, and when below 4 mg/dl, patients were started on oral prednisone 1 mg/kg per day for 7 days. Patients whose families did not consent to steroid treatment served as the control group. Patients were followed after discharge until symptoms resolved and all medications were discontinued.

RESULTS

Thirty-one children were diagnosed with orbital cellulitis during the study period. Of these 31 children, 24 received oral steroids (77%) and 7 did not (23%). There were 19 males and 5 females in the steroid group with an average age of 8.1 years, and 6 males and 1 female in the nonsteroid group with an average age of 7.1 years (p = 0.618). Thirteen patients (54%) in the steroid group and 2 patients (29%) in the nonsteroid group underwent sinus surgery with or without orbitotomy (p = 0.394). The average CRP at the onset of steroid treatment was 2.8 mg/dl (range: 0.5-4). Patients who received oral steroids were admitted for an average of 3.96 days. In comparison, patients who did not receive steroids were admitted for an average of 7.17 days (p < 0.05). Once CRP was ≤4 mg/dl, patients treated with steroids remained in the hospital for another 1.1 days, while patients who did not receive steroids remained hospitalized for another 4.9 days (p < 0.01). In the steroid group, 2 families reported increased hyperactivity in their children while on steroids. There was 1 case in each group of recurrence of symptoms after discharge from the hospital. Average follow-up time was 2.4 months in the steroid group and 2 months in the nonsteroid group (p = 0.996). At last visit, all patients returned to their baseline ophthalmic examination. There were no cases of vision loss or permanent ocular disability in either group.

CONCLUSIONS

Our results give further evidence of the safety and benefit of systemic steroids in children with orbital cellulitis. Futhermore, this is the first study to suggest a standardized starting point (CRP ≤ 4 mg/dl) and dosing schedule (oral prednisone 1 mg/kg for 7 days) for children with orbital cellulitis. Patients who received systemic steroids after CRP dropped below 4 mg/dl were discharged from the hospital earlier than patients who did not receive systemic steroids.

Recombinant antibody fragments allow repeated measurements of C-reactive protein with a quartz crystal microbalance immunosensor

C-reactive protein (CRP) is a serum marker highly upregulated in inflammation after bacterial infection. Robust, reliable and quick quantification of CRP would be a substitute for erythrocyte sedimentation rate (ESR) with superior diagnostic value. Quartz crystal microbalance (QCM) based sensors coated with specific antibodies and integrated into lab-on-chip systems are in development for rapid point of care quantification. In this study, we isolated three CRP specific single chain (sc)Fv antibody fragments using phage display from an antibody gene library. Their affinities ranged from 2.7 × 10(-8) to 1.0 × 10(-8) M when measured by surface plasmon resonance. ScFv antibody fragment LA13-IIE3 showed best affinity, high long-term stability and remarkable resistance to denaturation. This scFv antibody fragment was coupled to a QCM sensor. CRP quantification in up to 15 samples sequentially measured on the same sensor with intermitting regeneration by buffer was demonstrated.

Early murine immune responses from endotracheal exposures to biotechnology-related Bacillus strains

An immunology-based in vivo screening regime was used to assess the potential pathogenicity of biotechnology-related microbes. Strains of Bacillus cereus (Bc), Bacillus subtilis (Bs), Bacillus thuringiensis (Bt), and Bt commercial products (CPs) were tested. Balb/c mice were endotracheally instilled with purified spores, diluted CP, or vegetative cells (VC) (live or dead). Exposed mice were evaluated for changes in behavioral and physical symptoms, bacterial clearance, pulmonary granulocytes, and pulmonary and circulatory pyrogenic cytokines (interleukins (IL)-1β, IL-6 and tumor necrosis factor (TNF)-α), as well as acute phase biomarkers (fibrinogen and serum amyloid A). Except for some differences in clearance rates, no marked effects were observed in mice exposed to any spore at 10(6) or 10(7) colony forming units (cfu). In contrast, live Bc or Bt VCs (10(5) or 10(6) cfu) produced shock-like symptoms (lethargy, hunched appearance, ruffled fur, and respiratory distress), and 11-200-fold elevations in pyrogenic cytokines at 2-h post-exposure. In the study, 4-h effects included increased lethargy, ocular discharge, and 1.5-4-fold rise in circulatory acute phase markers, but no indications of recovery. Bs VC did not produce any changes in symptoms or biomarkers. After 2 or 4 h of exposure to dead VC, increases of only plasma IL-1? and TNF-α (4.6- and 12.4-fold, respectively) were observed. These findings demonstrate that purified spores produced no marked effects in mice compared to that of metabolically active bacteria. This early screening regime was successful in distinguishing the pathogenicity of the different Bacillus species, and might be useful for assessing the relative hazard potential of other biotechnology-related candidate strains.

The management of infections in children in general practice in Sweden: a repeated 1-week diagnosis-prescribing study in 5 counties in 2000 and 2002

A diagnosis-prescribing study was performed in 5 Swedish counties during 1 week in November in 2000 and repeated in 2002. The aim of the present study was to analyse data for children 0-15y of age who consulted a general practitioner with symptoms of an infection. During the 2 weeks studied, 4049 children were consulted. Respiratory tract infections (RTI) were the predominant diagnoses, above all among the youngest children, while the proportion of urinary tract infections and skin infections increased with increasing age. Between the y 2000 and 2002, the proportion of children allocated the diagnosis streptococcal tonsillitis and pneumonia decreased (p<0.01 and p<0.001, respectively) while the proportion of common cold increased (p<0.001). Antibiotic prescribing decreased from 55% to 48% (p<0.001) for respiratory infections between the years studied. The only significant changes in type of antibiotics prescribed were the increase of isoxazolylpenicillins (p<0.001) used for skin infection and the decrease of macrolides (p=0.001). A diagnostic test was used in more than half of the consultations. Of children allocated a RTI diagnosis, 36% were prescribed antibiotics when a C-reactive protein test was performed compared to 58% in those not tested. Further studies are needed in general practice to determine the optimal use of near-patient tests in children with RTI.

Automatic 3-dimensional visualization of peripheral blood slides: a new approach for the detection of infection/inflammation at the point of care

CONTEXT

The identification and quantitation of the intensity of the acute-phase response at the point of care might be of clinical relevance.

OBJECTIVE

To report the possibility of automatic screening of unstained peripheral blood slides by using a 3-dimensional image analysis system.

DESIGN

Peripheral venous blood was obtained from children with acute inflammation/infection and examined by an automatic 3-dimensional image analyzer to detect the number of white blood cells as well as to reveal the degree of erythrocyte aggregation, a marker of the humoral phase response.

RESULTS

We included 66 children with acute bacterial infections and 59 with nonbacterial inflammation/infection; mean ages of the 2 groups were 4.3 +/- 3.9 years and 4.2 +/- 3.7 years, respectively (P = .91). The percentages of correct classifications based on discriminant analysis in predicting between bacterial and nonbacterial inflammation/infection were 61.3% by using the white blood cell count, 64.5% by using the percentage of granulocytes, 61.6% by using the degree of erythrocyte aggregation, and 59.2% by using the number of leukocytes counted on the unstained slides. The results of the receiver-operated characteristic curve analysis yielded an area under the curve of 0.714 (P < .001) for the number of granulocytes, 0.699 (P < .001) for the white blood cell count, 0.685 (P < .001) for the number of leukocytes on the slides, and 0.685 (P = .001) for the degree of erythrocyte aggregation. The correlation between the number of leukocytes by the electronic cell analyzer and the number of cells counted on the slides was highly significant (r = 0.85, P < .001).

CONCLUSIONS

It is feasible to use an automatic 3-dimensional image analyzer to reveal the different intensities of the acute-phase response between a group of children with an acute bacterial infection and another with nonbacterial inflammation/infection. These findings might be relevant for potential application at the point of care.

Evaluation of a rapid bedside test for the quantitative determination of C-reactive protein

Regardless of its origin, any condition associated with inflammation is accompanied by an increase in serum C-reactive protein levels. This study compared the results of a rapid test for the bedside assay of C-reactive protein (QuikRead CRP, Orion Corporation, Orion Diagnostica, Espoo, Finland) with those of a standard laboratory assay in samples taken from 231 children aged less than 14years (126 males; median age 4.7years) attending the Emergency Department of Milan University's Institute of Pediatrics because of acute respiratory infection. The two methods showed similar median C-reactive protein levels (standard laboratory assay: 34.7mg/L, range 4–199mg/L; QuikRead CRP: 33.3mg/L, range <8–196mg/L; p=0.779) and a similar distribution of children with C-reactive protein levels of <20mg/L, 20–70mg/L and >70mg/L. This study shows for the first time that the rapid QuikRead CRP test can be performed at the bedside or in an outpatient clinic and, in less than 5min, gives the same quantitative results as those obtained using a more complex routine laboratory method.