Sasithorn Likitnukul

Evaluation of sensitivity and specificity of rapid influenza diagnostic tests for novel swine-origin influenza A (H1N1) virus.

To the Editors: This letter presents the usefulness of the rapid influenza diagnostic tests (RIDTs) to screen patients with suspected novel swine-origin influenza A (H1N1) virus (S-OIVH1N1) during the outbreak in Bangkok, Thailand. On May 12, 2009 the first 2 laboratoryconfirmed cases of S-OIVH1N1 infection were reported from Thailand. Within a month outbreaks occurred in the community and schools. The standard for diagnosis is viral isolation or real time reverse transcriptasepolymerase chain reaction (RT-PCR), however the laboratory capacity is limited. Rapid influenza diagnostic tests (RIDTs) have been used to screen patients with suspected influenza, and they offer the advantage of providing a timely result that might impact patient care. The performance of current RIDTs in diagnosing S-OIVH1N1 is unknown. Therefore, we conducted a study to evaluate the sensitivity and specificity of RIDTs against RT-PCR for novel H1N1 in the background of seasonal influenza in a private health care setting. From June 11 to July 28, 2009, 3096 patients presented with influenza-like illness at the outpatient clinic of Bangkok Christian Hospital and were tested with RIDTs. Only 841 (27%) of the patients had a nasal swab specimen tested with both RIDTs and confirmatory RT-PCR assay. The Quick Vue Influenza A B test (Quidel Corporation, CA, USA) (N 477) or SD bioline influenza antigen test (Standard Diagnostics, Inc., Gyeonggi-do, Korea) (N 364) was performed at the hospital laboratory. The RT-PCR assay was performed at the virology unit, Department of Pathology, Ramathibodi Hospital of Mahidol University. We calculated the sensitivity, specificity, accuracy, positive and negative predictive values, as well as 95% confidence intervals calculated using binomial exact methods, for each RIDT compared with confirmatory influenza testing by RTPCR assay. All of the calculations were performed by using VassarStats (http://faculty. vassar.edu/lowry/clin1.htm). The median age was 13 years (range, 6 months to 97 years); 16.2%, 19.4%, 37.4%, and 27% were younger than 5 years, 6–10 years, 11–20 years, and 20 years. There were 459 (55%) males. Of 3096 nasal swabs tested by RIDTs, 1027 were positive for influenza A (33.2%), and 19 were positive for influenza B (0.61%). Among 841 patients, RIDTs were positive for 376 out of 429 of S-OIVH1N1 confirmed cases, and 118 out of 140 seasonal influenza A. RIDTs were positive for 85 out of 272 patients who had negative RT-PCR tests for both S-OIVH1N1 or seasonal influenza A. The sensitivity and specificity of the RIDTs were 87.6% or 50.7%, respectively. The test parameters are presented in Table 1. Previous studies have described low sensitivity in the range of 17.8% to 51% and high specificity in the range of 93.6 to 99% for detecting S-OIVH1N1 compared with RT-PCR assay. Unlike previous reports, our data show high sensitivity and moderately accuracy for detecting S-OIVH1N1 in the background of seasonal influenza virus activity. The high sensitivity of the test might be explained by the study population, of whom the majority were children who had more viral shedding, and also by the high quality of specimen collection. The low specificity and low positive predictive value of the RIDTs compared with RT-PCR for S-OIVH1N1 may be due to cocirculation of seasonal influenza in the community. Since false negative results can occur, if clinical suspicion of influenza is high in a patient who tests negative by RIDTs, empiric antiviral therapy should be administered based on severity of illness, underlying medical condition, and risk for complications. In conclusion, our findings demonstrate the results of RIDTs, which are highly sensitive and moderately accurate for detecting S-OIVH1N1 in the background of seasonal influenza virus activity. The RIDTs are simple to perform with results available within 30 minutes. The results of RIDTs have clinical and public health implications and have been used to promptly detect S-OIVH1N1 and seasonal influenza virus infections. They allow early appropriate use of antiviral therapy and implementation of outbreak-control interventions, and also obviate further unnecessary diagnostic tests.

The immunogenicity and safety of pneumococcal conjugate vaccine in human immunodeficiency virus-infected Thai children.

BACKGROUND HIV-infected children have high risk of invasive pneumococcal disease (IPD) despite receiving highly active antiretroviral therapy (HAART). This study aimed to determine the immunogenicity and safety of a 7-valent pneumococcal conjugate vaccine (PCV-7) in Thai HIV-infected children compared to HIV-exposed uninfected children. METHODS A prospective study was conducted among children 2 months to 9 years. The number of PCV-7 doses depended upon age and HIV status; 2-6 months of age: 3 doses; 7-23 months of age: 2 doses; HIV-infected child ≥24 months: 2 doses and HIV-exposed child ≥24 months: 1 dose. Serotype-specific pneumococcal IgG antibody concentrations were measured at baseline and 28 days after complete vaccination. The primary end point was the proportion of children who achieved serotype-specific IgG antibody concentration at a cut off level ≥0.35 μg/mL. Secondary end points were a 4-fold increase in serotype-specific IgG antibody, rates of adverse events and predictors for seroconversion among HIV-infected children. RESULTS Fifty-nine HIV-infected and 30 HIV-exposed children were enrolled. The median (IQR) age was 97 (67-111) and 61 months (51-73), respectively (p<0.001). Among HIV-infected children, current and nadir CD4 counts were 1,079 cell/mm(3) and 461 cell/mm(3), respectively. The proportion of children who achieved pneumococcal IgG ≥0.35 μg/mL was in the range of 85-98% in HIV-infected and 83-100% in HIV-exposed children depending on serotype. The lowest response was to serotype 6B in both groups. The 4-fold increase in serotype-specific IgG concentrations was similar between HIV-infected and HIV-exposed groups, except for serotype 9V (p=0.027). HIV-infected children who had a history of AIDS had a lower antibody response to serotype 23F (p=0.025). Seven (12%) HIV-infected children had a grade 3 local reaction. CONCLUSION PCV-7 is highly immunogenic and safe among HIV-infected children treated with HAART. The use of the pneumococcal conjugate vaccine among HIV-infected children is encouraged in order to prevent IPD.

Appendicitis-like syndrome owing to mesenteric adenitis caused by Salmonella typhi

Abstract We report a 14-year-old girl who presented with signs of appendicitis and had her appendix removed. She subsequently proved to have mesenteric adenitis owing to Salmonella typhi which responded to treatment with ceftriaxone.

Measles-Associated Appendicitis: Two Case Reports and Literature Review

We report 2 cases of appendicitis associated with measles. Four previously reported cases are reviewed. In all 6 patients typical measles rash appeared after removal of the appendix, which showed Warthin-Finkelday giant cells.We report 2 cases of appendicitis associated with measles. Four previously reported cases are reviewed. In all 6 patients typical measles rash appeared after removal of the appendix, which showed Warthin?Finkelday giant cells.

Endocarditis caused by drug-resistant Streptococcus pneumoniae in a child.

We report a case of infective endocarditis caused by drug-resistant Streptococcus pneumoniae. Cefazolin or cefotaxime therapy induced a partial response. Treatment with vancomycin was successful. This microorganism may be more significant in endocarditis in areas with a high prevalence of drug-resistant Streptococcus pneumoniae.

Immunogenicity and safety of a pediatric dose virosomal hepatitis A vaccine in Thai HIV-infected children

The immunogenicity and safety of a pediatric dose of a virosomal hepatitis A vaccine (Epaxal®) was evaluated in a group of 45 Thai children with human immunodeficiency virus (HIV) infection, age 2-16 years. Vaccines were administered at 0 and 6 months. Anti-HAV antibody titers were measured at baseline (before injection) 1 and 7 months after primary vaccination. The prevalence of HAV protective antibody in 45 Thai HIV-infected children was 13.6%. The seroprotection rate was 71% at 1 month and 100% at 7 months. The booster dose increased geometric mean concentration (GMC) from 106.5 mIU/ml to 3486.1 mIU/ml. Higher CD4 lymphocyte counts at enrollment was a predictive factor for HAV antibody response. Both doses of Epaxal® were well tolerated. These preliminary data suggest that a pediatric dose of Epaxal® is an effective hepatitis A vaccine for HIV-infected children and should be considered for implementation on a larger scale in the pediatric HIV population.

Post-operative meningitis caused by drug-resistant Streptococcus pneumoniae: two case reports.

We report 2 patients with post-operative meningitis caused by drug-resistant Streptococcus pneumoniae (DRSP), following correction of frontoethmoidal encephalomeningocele in 1 patient and adenotonsillectomy in the other. Both patients responded well to vancomycin plus cefotaxime. DRSP may be colonized in the upper respiratory tract and causes serious infections after surgical operation.

Prevalence of Chlamydia pneumoniae infection in Thai children with community-acquired pneumonia.

The prevalence of Chlamydia pneumoniae infection in children with community-acquired pneumonia was investigated at Chulalongkorn Hospital, Bangkok from 1999 through 2001. Serologic evidence of acute C. pneumoniae infection was found in 149 of 333 (44.7%) children, of whom 132 of 149 (88%) were <5 years of age. The findings provide further evidence that C. pneumoniae infection is common in very young children.