Jong-Min Chen

High Prevalence of Antimicrobial Resistance in Rapidly Growing Mycobacteria in Taiwan

ABSTRACT An increasing number of clinical isolations of rapidly growing mycobacteria (RGM) at the National Taiwan University Hospital were noted from 1992 to 2001. Broth microdilution MICs of 15 antimicrobial agents were determined for 200 clinical isolates of RGM, including the Mycobacterium fortuitum group (69 isolates), M. chelonae (39 isolates), and M. abscessus (92 isolates). Our results showed that the resistance rates of these isolates to the currently available agents were remarkably high. Amikacin was active against nearly all RGM isolates. Clarithromycin was usually active against M. abscessus (79% susceptibility) and the M. fortuitum group (65% susceptibility). The majority of M. fortuitum group isolates were susceptible to ciprofloxacin (62%) and imipenem (61%). The susceptibilities to other conventional anti-RGM agents of these isolates were poor but differed markedly by species. The newer fluoroquinolones (levofloxacin, moxifloxacin, and gatifloxacin) and meropenem showed better in vitro activities against the M. fortuitum group isolates than against the other two species of RGM. Linezolid had fairly good activity against these RGM isolates, particularly against M. chelonae isolates (82% susceptible). Telithromycin had poor activity against these RGM isolates (the MICs at which 50% of the isolates tested are inhibited [MIC50s] were 32 to 64 μg/ml, and the MIC90s were >64 μg/ml).

Meningitis caused by human herpesvirus-6.

Since the discovery of human herpesvirus-6 (HHV-6) the illnesses associated with it have increased steadily. Two infants with meningitis are reported: both suffered a mild meningitis and serological studies confirmed an acute HHV-6 infection. This report supports a role of HHV-6 in nervous system disease.

Risk factors of hepatitis during Anti-tuberculous treatment and implications of hepatitis virus load

OBJECTIVES Hepatitis during anti-tuberculous treatment (HATT) has been an obstacle in managing patients with tuberculosis (TB). We evaluate the risk factors of HATT and the clinical implications of serum viral loads in those with concomitant hepatitis B or C viruses (HBV/HCV) infection. METHODS We did a prospective study on patients with pulmonary tuberculosis in a medical center. HATT was defined as an increase in serum transaminase level of >3 times the upper limit of normal (ULN) with symptoms, or an increase in serum transaminase level of >5 times ULN without symptoms. RESULTS 360 TB patients were studied. The prevalence of concomitant HBV and HCV infection was 11.7% and 6.7%, respectively. HATT developed in 68 (18.9%). Cox regression analysis revealed that severe chronic kidney disease without hemodialysis, N-acetyltransferase (NAT2) slow acetylator, high initial HBV/HCV viral load, and women in those without HBV/HCV infection were significant predictors of drug-induced HATT, whereas severe chronic kidney disease without hemodialysis and men with high initial HBV/HCV viral load were significantly associated virus-induced HATT. CONCLUSION HBV/HCV viral load interacts with gender and, together with severe chronic kidney disease without hemodialysis and NAT2 slow acetylator, were predictors of HATT. TB patients with these characteristics need close follow-up.

Evaluation of the Bruker Biotyper Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry System for Identification of Blood Isolates of Vibrio Species

ABSTRACT Among 56 blood isolates of Vibrio species identified by sequencing analysis of 16S rRNA and rpoB genes, the Bruker Biotyper matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) system correctly identified all isolates of Vibrio vulnificus (n = 20), V. parahaemolyticus (n = 2), and V. fluvialis (n = 1) but none of the isolates of serogroup non-O1/O139 (non-serogroup O1, non-O139) V. cholerae (n = 33) to the species level. All of these serogroup non-O1/O139 V. cholerae isolates were correctly identified using the newly created MALDI-TOF MS database.

A follow-up study of combined vaccination with plasma-derived and recombinant hepatitis B vaccines in infants

This study was aimed to evaluate the efficacy and immunogenicity of combined hepatitis B vaccination with plasma-derived vaccine (PDV) and recombinant vaccine (RV). A total of 329 infants was recruited, including 224 high-risk infants born to hepatitis B e antigen-positive mothers and 105 low-risk infants born to hepatitis B e antigen-negative mothers. The high-risk infants received four doses of hepatitis B vaccine at 0, 1, 2 and 12 months of age with five different schedules. Group A1 and A2 infants were vaccinated with PDV as the first dose and RV (SB vaccine for group A1, MSD vaccine for group A2) as the remaining three doses. Group B1 and group B2 infants were vaccinated with PDV as the first two doses and RV (SB vaccine for group B1, MSD vaccine for group B2) as the remaining two doses. Group C infants received four doses of PDV. Low-risk infants were vaccinated with PDV at birth, and RV at 1 and 6 months of age (group D1, using SB vaccine; group D2, using MSD vaccine). At completion of vaccination schedules, 20 of 224 high-risk infants (9%) were positive for hepatitis B surface antigen. The overall protective efficacy was 90%. Hepatitis B surface antibody (anti-HBs)-positive rate ranged between 94 and 100% among the remaining infants. The protective efficacy and immunogenicity were similar among groups except that the mean level of anti-HBs in group C, D1 and D2 infants tended to be lower than that of the other four groups. To ensure an optimal immune response, four doses of vaccine are recommended in high-risk infants when two types of vaccine are to be used in combination.

Comparison of real-time polymerase chain reaction and serological tests for the confirmation of Mycoplasma pneumoniae infection in children with clinical diagnosis of atypical pneumonia.

BACKGROUND Mycoplasma pneumoniae is a common pathogen of respiratory tract infection in children, and its correct and rapid diagnosis is a clinical challenge. Real-time polymerase chain reaction (RT-PCR) has been used frequently for the detection of this pathogen. MATERIALS AND METHODS Medical records from all children with a clinical diagnosis of mycoplasma pneumonia and whose respiratory samples were tested for M. pneumoniae (using RT-PCR) during 2011 were reviewed retrospectively. We compared the sensitivity and specificity of serological assays versus those of RT-PCR for diagnosis of M. pneumoniae infections. We also reviewed retrospectively clinical characteristics, and laboratory and imaging findings of children with laboratory evidence of M. pneumoniae infection. RESULTS In 2011, 290 children were diagnosed to have mycoplasma pneumonia clinically and had their respiratory samples tested for M. pneumoniae by RT-PCR. Fifty-four children (19%) had a positive result. Meanwhile, 63% (182/290) of these children also underwent serological tests, out of whom 44 (24%) were found to be positive for immunoglobulin M (IgM). Using PCR as a gold standard, M. pneumoniae IgM assay was found to show a sensitivity of 62.2% and a specificity of 85.5%. Positive and negative predictive values of IgM were 52.3% and 89.9%, respectively. In M. pneumoniae IgM-positive children, a negative PCR result was associated with more coinfection by other pathogens and longer duration of prehospitalization fever. Bacterial loads of M. pneumoniae were not correlated with clinical outcomes. CONCLUSION The majority of clinically diagnosed mycoplasma pneumonia was unconfirmed. Mycoplasma pneumoniae IgM has poor sensitivity and a positive predictive value. Interpretation of Mycoplasma pneumoniae IgM should be done with caution.

Chronological Changes in Genetic Variance and Heritability of Anthropometric Characteristics Among Chinese Twin Infants

In order to examine the chronologic changes in genetic variance and heritability of anthropometric characteristics of Chinese infants in Taiwan, a total of 521 pairs of same-sexed twin neonates given birth in four major general teaching hospitals in Taipei City were studied. Based on the placental pattern and 12 red blood cell antigens, 428 MZ and 93 DZ twin pairs were identified and followed up to the age of one year. There was no significant genetic variance for all anthropometric characteristics adjusted for sex and gestational week before the age of six months. After adjusting for sex and gestational week, a significant genetic variance was observed at the age of six months, with heritability values of 0.51 (weight), 0.63 (head circumference), 0.77 (chest circumference), and 0.53 (arm circumference), as well as at one year, although with considerably lower heritability values. This implies that growth is dynamically determined by both genetic and environmental factors during infancy.

Hypoglycemia associated with bacteremic pneumococcal infections

OBJECTIVES To evaluate the prevalence and associated presentations of hypoglycemia in bacteremic pneumococcal infections, and serotypes of the isolates. METHODS This was a retrospective study of 70 episodes of pneumococcal bacteremia that occurred in 2004 and 2005. RESULTS We found hypoglycemia (plasma glucose<3.05 mmol/l)) in six (8.6%) episodes. The patients were three children (mean age 3 years 1 month; range 1 year 5 months-4 years 5 months) and three adults (mean age 73.3 years; range 63-84 years). One child with asplenia and cyanotic heart disease had primary pneumococcal bacteremia. Of the other two children, one had meningitis and the other pneumonia. All the adults had cancer with previous chemotherapy and multilobar pneumonia, which progressed rapidly to respiratory failure. All patients developed their first hypoglycemic episode within two hours after presentation. The average plasma glucose during hypoglycemia was 1.78+/-0.78 mmol/l (range 0.33-2.94 mmol/l). One child and all of the adults died. Serotypes of isolates were those usually associated with severe pneumococcal infection: 6B and 19F in the children; 3, 14, and 23F in the adults. Only the asplenic child had received pneumococcal vaccine. CONCLUSIONS Hypoglycemia occurred in 8.6% of bacteremic pneumococcal infections and was associated with high mortality and serotypes that cause severe invasive disease. All patients suspected of having septicemia should have their glucose checked to avoid missing hypoglycemia leading to a worsening of their already poor condition.

A simplified schedule to integrate the hepatitis B vaccine into an expanded program of immunization in endemic countries

OBJECTIVE To investigate the safety, immunogenicity, and efficacy of a simplified hepatitis B vaccination schedule. METHODS The second dose of hepatitis B vaccine and the first dose of diphtheria-tetanus-pertussis (DTP) vaccine were given simultaneously at age 6 weeks. The second dose of DTP vaccine was given at age 3.5 months. The third dose of DTP vaccine and the third dose of hepatitis B vaccine were given at age 5.5 months. One hundred three infants (group A) born to mothers without hepatitis B surface antigen (HBsAg) received DTP with whole-cell pertussis vaccine. Fifty-five infants (group B) born to mothers with HBsAg and hepatitis B e antigen received DTP with acellular pertussis vaccine. RESULTS By age 9 months, none of group A and 4 (7%) group B infants were sero-positive for HBsAg. The protective efficacy against the hepatitis B carrier state in these infants at high risk was 92%. Antibody to hepatitis B surface antigen was 10 mlU/ml or greater in 99 (96%) of group A infants and in 50 (91%) of group B infants. Both the acellular and whole-cell DTP vaccines were immunogenic, and the incidences of adverse reactions were within an expected and acceptable range. CONCLUSIONS The simplified vaccination schedule to integrate the hepatitis B vaccine into the Expanded Programme of Immunization was safe, Immunogenic, and effective. This schedule may improve vaccine compliance and be applied to DTP and hepatitis B combination vaccines now under investigation.

Chronological changes in genetic variance and heritability of systolic and diastolic blood pressure among Chinese twin neonates.

In order to examine the chronological changes in genetic variance and heritability of arterial systolic and diastolic blood pressure (SBP and DBP of Chinese infants in Taiwan, a total of 339 same-sexed twin neonates born in four major general teaching hospitals in Taipei City were studied. Based on placentation and 12 red blood cell antigens, 274 monozygotic (MZ) and 65 dizygotic (DZ) twin pairs were identified and followed up to the age of one year. Both SBP and DBP were measured by Doppler blood pressure monitor. Within-pair mean squares of SBP and DBP were consistently smaller in MZ than DZ twins at ages one month and over. The findings remained unchanged after the adjustment for the effects of age, sex, gestational age, placentation and physical state during blood pressure measurement. Falconers heritability indices for adjusted SBP and DBP at ages two months and over ranged from 0.29 to 0.55 and from 0.27 to 0.45, respectively. The study indicates an important genetic influence on blood pressure during infancy.