Fecal alpha1--antitrypsin in healthy and intestinal-disorder Thai children.

OBJECTIVE: Determine the normal FA1-AT level in random wet stool of Thai children using RID and NPL, and to study the correlation between RID and NPL methods for measurement of FA1-AT. MATERIAL AND METHOD: Random stool samples were collected from healthy children and intestinal-disorders patients. Alpha1-antitrypsin (FA1-AT) in wet stool samples was measured by nephelometry (NPL) and radial-immunodiffusion (RID) methods. RESULTS: Newborn infants had the highest FA1-AT level during the first day of life and declined to the same level as older children on day 3-4. Median and geometric mean of FA1-AT levels by NPL from healthy children aged 1 month-15 years was 1.23 and 1.11 mg/dL respectively. FA1-AT levels by NPL from children with severe intestinal disorders, displaying median and geometric mean at 6.77 and 12.39 mg/dL respectively, were much higher than healthy children. The RID and NPL methods showed a correlation of r = 0.87 (p < 0.01) and R2 = 0.75. CONCLUSION: Random FA1-AT assay in wet stool is a non-invasive and simple test for supporting diagnosis of protein-losing enteropathy.

Prevalence and clinical features of mycoplasma pneumoniae in Thai children.

OBJECTIVE: To determine the prevalence and clinical features of mycoplasma pneumoniae in Thai children with community acquired pneumonia (CAP). MATERIAL AND METHOD: Diagnosis of current infection was based on > or = 4 fold rise in antibody sera or persistently high antibody titers together with the presence of mycoplasma DNA in respiratory secretion. The clinical features were compared between children who tested positive for M pneumoniae, and those whose results were negative. RESULTS: Current infection due to M. pneumoniae was diagnosed in 36 (15%) of 245 children with paired sera. The sensitivity and specificity of polymerase chain reaction (PCR) in diagnosing current infection in the present study were 78% and 98% respectively. The mean age of children with mycoplasma pneumoniae was higher than CAP with unspecified etiology. The presenting manifestations and initial laboratory finding were insufficient to predict mycoplasma pneumoniae precisely, the presence of chest pain and lobar consolidation on chest X-ray, however, were significant findings in children with mycoplasma pneumoniae. CONCLUSION: The present study confirms that M. pneumoniae plays a significant role in CAP in children of all ages. Children with this infection should be identified in order to administer the appropriate antibiotic treatment.

Prevalence and clinical presentations of atypical pathogens infection in community acquired pneumonia in Thailand.

OBJECTIVES: To determine the prevalence of atypical pneumonia and clinical presentations in patients with community acquired pneumonia (CAP). MATERIAL AND METHOD: A prospective multi-centered study was performed in patients aged > or = 2 years with the diagnosis of CAP who were treated at seven governmental hospitals in Bangkok from December 2001 to November 2002. The diagnosis of current infection was based on > or = 4 fold rise in antibody sera or persistently high antibody titers together with the presence of DNA of M. pneumoniae or C. pneumoniae in respiratory secretion or antigen of L. pneumophila in the urine. Clinical presentations were compared between patients with atypical pneumonia and unspecified pneumonia. RESULTS: Of 292 patients, 18.8% had current infection with atypical respiratory pathogens (M. pneumoniae 14.0%, C. pneumoniae 3.4%, L. pneumophila 0.4% and mixed infection 1.0%). Only age at presentation was significantly associated with atypical pneumonia in adults, while absence of dyspnea, lobar consolidation, and age > or = 5 years were significant findings for atypical pneumonia in children. CONCLUSION: The present study confirms the significance of atypical pathogens in adults and children. Moreover lobar consolidation is likely to predict atypical pneumonia in childhood CAP.

Raising rheumatoid factor cutoff helps distinguish rheumatoid arthritis.

The presence of rheumatoid factor (RF) is one of the clinical criteria for the diagnosis of rheumatoid arthritis (RA). The cutoff point of RF assays is usually based on a reference level obtained from normal subjects in the same population as the patients. We evaluated 63 rheumatoid arthritis (RA), 25 other arthritis patients and 110 blood donors. Their rheumatoid factors (RF) ranged from < 9.9 to 2,264, < 9.9 to 262, and < 9.9 to 66 mIU/ml, respectively. The sensitivity at different cutoff points of 15, 20, and 25 mIU/ml was 92.1%, 90.5%, and 88.9%, respectively. The specificity at the same cutoff points was 81.5%, 84.4%, and 85.2%, respectively. Having minimally sacrificed the sensitivity, we recommend using a higher RF cutoff to increase specificity.

Evaluation of in-house optimized semi-nested PCR and EIA for direct detection of mycobacterial DNA in CSF.

A rapid and correct diagnosis of mycobacterial infections is important for effective patient treatment. Semi-nested-PCR with Fl-16 SOL, 16SOR and 16SNSR primers based on the 16S rRNA gene, under optimized conditions, can detect 499 bp amplified products from all tested mycobacteria. The assay could detect as little as 100 fg of mycobacterial DNA except for rapid growing mycobacteria, whose detection limits ranged from 1 ng to 10 pg. The specificities of the capture probes were assessed with 96 mycobacterial strains (22 species) and 33 nonmycobacterial strains (30 species). The specificities of pAll1, pTbc1 and pMar1 were 94%, 93% and 82%, respectively, and that of pAvi1, pInt1, pChe1 and pFor1 were 100%. The pTbc1 and pAvi1 were tested with DNA from 108 CSF samples, and the sensitivity and specificity of the detection method were 56% and 84% compared to culture and patient histories. The assay should be used for rapid detection and concurrent identification of slow growing mycobacteria without parallel conventional culture verification.

Reversed passive hemagglutination test fails to detect HBsAg in a number of HBeAg positive sera.

In endemic areas of hepatitis B virus (HBV) infection, perinatal transmission from asymptomatic HBsAg carrier mothers to infants plays a major role in the transmission of HBV. HBeAg indicates a high level of viral replication and infectivity. Most of the infants born to HBeAg positive mothers become carriers. Prenatal screening of HBsAg would identify infected mothers and thus allow preventive administration of immunoglobulin and immunization to the newborns. Reversed passive hemagglutination assay (RPHA) is commonly used in Thailand for HBsAg screening. However this method has low sensitivity and gives false negative results. Therefore, infants born to HBsAg false negative mothers would not receive proper immunization. This study reveals the rate of false negative results for HBsAg by RPHA in high infectivity sera. Of 985 sera which were HBsAg positive by ELISA, 70 (7.1%) were negative for HBsAg by RPHA. Of these 70 false negative sera, 7 (10%) were HBeAg positive. Our results indicate that RPHA is a less sensitive method for detection of HBsAg than ELISA. RPHA can give false negative results even in sera with high HBV infectivity. Therefore, RPHA should be replaced by EIA for prenatal HBsAg screening or any other screening for HBV infection whenever possible.