An Improved PCR-RFLP Assay for Detection and Genotyping of Asymptomatic Giardia lamblia Infection in a Resource-Poor Setting

Laboratory workers, in resource-poor countries, still consider PCR detection of Giardia lamblia more costly and more time-consuming than the classical parasitological techniques. Based on 2 published primers, an in-house one-round touchdown PCR-RFLP assay was developed. The assay was validated with an internal amplification control included in reactions. Performance of the assay was assessed with DNA samples of various purities, 91 control fecal samples with various parasite load, and 472 samples of unknown results. Two cysts per reaction were enough for PCR detection by the assay with exhibited specificity (Sp) and sensitivity (Se) of 100% and 93%, respectively. Taking a published small subunit rRNA reference PCR test results (6%; 29/472) as a nominated gold standard, G. lamblia was identified in 5.9% (28/472), 5.2%, (25/472), and 3.6% (17/472) by PCR assay, RIDA® Quick Giardia antigen detection test (R-Biopharm, Darmstadt, Germany), and iodine-stained smear microscopy, respectively. The percent agreements (kappa values) of 99.7% (0.745), 98.9% (0.900), and 97.7% (0.981) were exhibited between the assay results and that of the reference PCR, immunoassay, and microscopy, respectively. Restriction digestion of the 28 Giardia-positive samples revealed genotype A pattern in 12 and genotype B profile in 16 samples. The PCR assay with the described format and exhibited performance has a great potential to be adopted in basic clinical laboratories as a detection tool for G. lamblia especially in asymptomatic infections. This potential is increased more in particular situations where identification of the parasite genotype represents a major requirement as in epidemiological studies and infection outbreaks.

FEV1 and FVC pulmonary function reference values among 6-18-year-old children: a multi-centre study in Saudi Arabia

It is important to establish lung function reference values for each population. This study aimed to determine the spirometric reference values for healthy Saudi Arabian children and adolescents and to derive prediction equations for these. A cross-sectional study was conducted among healthy schoolboys and girls aged 6–18 years old, selected randomly from the 6 administrative regions of Saudi Arabia. Data were collected by questionnaire and physical examinations including spirometry. Forced expiratory volume in 1 second [FEV1] and forced vital capacity [FVC] were significantly higher in males than females. Height was the anthropometric variable most strongly correlated with FEV1 [r = 0. 61], more so for males [r = 0.71] than females [r = 0.50]. In males the multivariate linear regression model explained 53.9% of FEV1 and 35.1% of FVC variations. In females it explained 25.3% of FEV1 and 16.5% of FVC variations. All changes in R2 were statistically significant.