Biomedical subjects

T T Hien

Publications and source records attributed to T T Hien.

At least 19 recordsLinked to original sources

PubMed2006

A simple and rapid liquid chromatographic assay for evaluation of potentially counterfeit Tamiflu.

A simple and rapid liquid chromatographic assay for the evaluation of potentially counterfeit oseltamivir (Tamiflu has been developed and assessed. The assay uses approximately 1mg Tamiflu powder when used for authentication and content estimate. The procedure was validated using 50 replicates analysed during five independent series with a total R.S.D. of 11.2%. The assay can also be used to monitor the exact content of oseltamivir in Tamiflu capsules. One Tamiflu capsule was transferred to a 250mL volumetric flask and 150mL water was added. The flask was placed in an ultrasonic bath at 40 degrees C for 20min to dissolve the capsule. The solution was allowed to cool to room temperature before the flask was filled up to the mark (250mL). A small aliquot was centrifuged and then directly injected into the LC-system for quantification. Oseltamivir was analysed by liquid chromatography with UV detection on a Hypersil Gold column (150mmx4.6mm) using a mobile phase containing methanol-phosphate buffer (pH 2.5; 0.1M) (50:50, v/v) at a flow rate of 1.0mL/min. The assay was implemented for the analysis of Tamiflu purchased over the Internet and at local pharmacies in Thailand and Vietnam.

Acetamides↗

PubMed2006

Evolution and adaptation of H5N1 influenza virus in avian and human hosts in Indonesia and Vietnam.

Highly pathogenic avian influenza virus H5N1 is endemic in poultry in East and Southeast Asia with disease outbreaks recently spreading to parts of central Asia, Europe and Africa. Continued interspecies transmission to humans has been reported in Vietnam, Thailand, Cambodia, Indonesia and China, causing pandemic concern. Here, we genetically characterize 82 H5N1 viruses isolated from poultry throughout Indonesia and Vietnam and 11 human isolates from southern Vietnam together with sequence data available in public databases to address questions relevant to virus introduction, endemicity and evolution. Phylogenetic analysis shows that all viruses from Indonesia form a distinct sublineage of H5N1 genotype Z viruses suggesting this outbreak likely originated from a single introduction that spread throughout the country during the past two years. Continued virus activities in Indonesia were attributed to transmission via poultry movement within the country rather than through repeated introductions by bird migration. Within Indonesia and Vietnam, H5N1 viruses have evolved over time into geographically distinct groups within each country. Molecular analysis of the H5N1 genotype Z genome shows that only the M2 and PB1-F2 genes were under positive selection, suggesting that these genes might be involved in adaptation of this virus to new hosts following interspecies transmission. At the amino acid level 12 residues were under positive selection in those genotype Z viruses, in the HA and PB1-F2 proteins. Some of these residues were more frequently observed in human isolates than in avian isolates and are related to viral antigenicity and receptor binding. Our study provides insight into the ongoing evolution of H5N1 influenza viruses that are transmitting in diverse avian species and at the interface between avian and human hosts.

Animals↗

PubMed2004

Fake antimalarials in Southeast Asia are a major impediment to malaria control: multinational cross-sectional survey on the prevalence of fake antimalarials.

OBJECTIVE: To assess the prevalence of counterfeit antimalarial drugs in Southeast (SE) Asia. DESIGN: Cross-sectional survey. SETTING: Pharmacies and shops selling antimalarial drugs in Myanmar (Burma), Lao PDR, Vietnam, Cambodia and Thailand. MAIN OUTCOME MEASURES: Proportion of artemisinin derivatives or mefloquine containing drugs of substandard quality. RESULTS: Of the 188 tablet packs purchased which were labelled as 'artesunate' 53% did not contain any artesunate. All counterfeit artesunate tablets were labelled as manufactured by 'Guilin Pharma', and refinements of the fake blisterpacks made them often hard to distinguish from their genuine counterparts. No other artemisinin derivatives were found to be counterfeited. Of the 44 mefloquine samples, 9% contained <10% of the expected amount of active ingredient. CONCLUSIONS: An alarmingly high proportion of antimalarial drugs bought in pharmacies and shops in mainland SE Asia are counterfeit, and the problem has increased significantly compared with our previous survey in 1999-2000. This is a serious threat to public health in the region.

Antimalarials↗

PubMed2004

Comparative pharmacokinetics of intramuscular artesunate and artemether in patients with severe falciparum malaria.

The first-dose pharmacokinetic properties of intramuscular (i.m.) artesunate (ARTS; 2.4 mg/kg immediately [stat], followed by 1.2 mg/kg i.m. daily) and artemether (ARM; 3.2 mg/kg i.m. stat, followed by 1.6 mg/kg i.m. daily) were compared in Vietnamese adults with severe falciparum malaria. A total of 19 patients were studied; 9 received ARTS, and 10 received ARM. ARTS was absorbed very rapidly; concentrations in plasma peaked between 1,362 and 8,388 nmol/liter (median, 5,710 nmol/liter) within 20 min of injection and then declined with a median (range) half-life (t(1/2)) of 30 (3 to 67) min. ARTS was hydrolyzed rapidly and completely to the biologically active metabolite dihydroartemisinin (DHA). Peak DHA concentrations in plasma ranged between 1,718 and 7,080 nmol/liter (median, 3,060 nmol/liter) and declined with a t(1/2) of 52 (26 to 69) min. In contrast, ARM was slowly and erratically absorbed. The absorption profile appeared biphasic. Maximum ARM concentrations in plasma ranged between 67 nmol/liter (a value close to the 50% inhibitory concentration for some Plasmodium falciparum isolates) and 1,631 nmol/liter (median, 574 nmol/liter) and occurred at a median (range) of 10 (1.5 to 24) h. There was relatively little conversion to DHA. After i.m. injection in cases of severe malaria, absorption of the water-soluble ARTS is rapid and extensive, whereas the oil-based ARM is slowly and erratically absorbed, with relatively little conversion to the more active DHA. On the basis of this pharmacological study, parenteral ARTS is preferable to ARM as an initial antimalarial therapy, particularly in the most seriously ill patients. These findings should be formally assessed by a randomized clinical trial.

Adolescent↗

PubMed2004

The role of the polymerase chain reaction in the diagnosis of bacterial meningitis in Vietnam.

Bacterial meningitis remains an important cause of morbidity and mortality in Vietnam. Diagnosis is hampered by the ready availability of antibiotics in the community, leading to late presentation, masked clinical signs, and poor organism detection during the microscopical examination and culture of cerebrospinal fluid (CSF). In order to improve organism detection at the Hospital for Tropical Diseases in Ho Chi Minh City, a diagnostic PCR-based protocol was developed. This protocol was followed in the investigation of CSF samples from 36 patients with clinical signs of bacterial meningitis. Each sample was first tested in a semi-nested PCR using primers for the 16sRNA gene common to all bacteria. The products of this reaction were then amplified using a 16sru8 primer and primers specific for Neisseria meningitidis, Haemophilus influenzae or Streptococcus spp. The samples found positive for Streptococcus were further investigated in a nested PCR using primers specific for the pneumolysin gene of S. pneumoniae. The sensitivity of detection was increased from 36% with culture to 44% with PCR. Although the sample size was small, the results indicate that PCR would be a feasible and useful adjunct in the diagnosis of bacterial meningitis, particularly in areas where community antibiotic use is common.

Antigens, Bacterial↗

PubMed2003

Neuropathological assessment of artemether-treated severe malaria.

In animals, high doses of intramuscular artemether and artemotil have been shown to cause an unusual pattern of selective damage to certain brainstem nuclei, especially those implicated in hearing and balance. We aimed to investigate whether a similar pattern arises in human adults. We examined the brainstems of adults who died after treatment with high dose artemether or quinine for severe falciparum malaria for evidence of a pattern of selective neuronal damage. Neuropathological findings were similar in recipients of quinine (n=15) and artemether (n=6; total artemether doses received 4-44 mg/kg). No evidence was recorded for artemether-induced neurotoxic effects.

Adult↗

PubMed2002

Malaria in injection drug abusers in Vietnam.

A prospective case-control study was conducted in a referral hospital in Ho Chi Minh City, Vietnam, to compare the clinical and laboratory features and outcome of severe falciparum malaria in injection drug abusers (IDAs) with those of patients who had acquired malaria by mosquito bite. From 1991 to 1996, 70 IDAs were admitted to the hospital, of whom at least 32 had acquired malaria by needle sharing. Although IDAs were more likely than control patients with severe malaria to be malnourished and to have coincident hepatitis B, hepatitis C, and human immunodeficiency virus infections, the overall rates of mortality, complications, and recovery were similar in the 2 groups. The route of malaria acquisition did not affect the outcome of severe malaria. The management of severe malaria in IDAs is similar to that for other patients.

Adolescent↗

PubMed2002

Assessment of the factors associated with flavivirus seroprevalence in a population in Southern Vietnam.

Dengue and Japanese encephalitis flaviviruses cause severe disease and are hyperendemic in southern Vietnam. This study assesses associations between sociodemographic factors and flavivirus seroprevalence in this region. Sera were collected from 308 community and hospital-based subjects between April 1996 and August 1997 and tested with an indirect ELISA. The factors associated with seroprevalence were assessed using multivariate logistic regression. In this first report of adjusted prevalence odds ratios (POR) for flavivirus infection in Vietnam, seropositivity was associated with increasing age in children (multiple regression coefficients for a child compared to an adult = -4.975 and for age in children = 0.354) and residence in the city compared to surrounding rural districts. The association with age indicates that subjects were most likely to have acquired infection in early childhood. This is key to the design of Vietnamese health education and immunization programmes.

Adolescent↗

PubMed2001

Complete genome sequence of a multiple drug resistant Salmonella enterica serovar Typhi CT18.

Salmonella enterica serovar Typhi (S. typhi) is the aetiological agent of typhoid fever, a serious invasive bacterial disease of humans with an annual global burden of approximately 16 million cases, leading to 600,000 fatalities. Many S. enterica serovars actively invade the mucosal surface of the intestine but are normally contained in healthy individuals by the local immune defence mechanisms. However, S. typhi has evolved the ability to spread to the deeper tissues of humans, including liver, spleen and bone marrow. Here we have sequenced the 4,809,037-base pair (bp) genome of a S. typhi (CT18) that is resistant to multiple drugs, revealing the presence of hundreds of insertions and deletions compared with the Escherichia coli genome, ranging in size from single genes to large islands. Notably, the genome sequence identifies over two hundred pseudogenes, several corresponding to genes that are known to contribute to virulence in Salmonella typhimurium. This genetic degradation may contribute to the human-restricted host range for S. typhi. CT18 harbours a 218,150-bp multiple-drug-resistance incH1 plasmid (pHCM1), and a 106,516-bp cryptic plasmid (pHCM2), which shows recent common ancestry with a virulence plasmid of Yersinia pestis.

Chromosome Mapping↗

PubMed2001

Typhoid fever and genetic polymorphisms at the natural resistance-associated macrophage protein 1.

Control of Salmonella enterica serovar Typhimurium (S. typhimurium) infection in the mouse model of typhoid fever is critically dependent on the natural resistance-associated macrophage protein 1 (Nramp1). In this study, we examined the role of genetic polymorphisms in the human homologue, NRAMP1, in resistance to typhoid fever in southern Vietnam. Patients with blood-culture-confirmed typhoid fever and healthy control subjects were genotyped for 6 polymorphic markers within and near NRAMP1 on chromosome 2q35. Four single base-pair polymorphisms (274 C/T, 469+14 G/C, 1465-85 G/A, and D543N), a (GT)(n) repeat in the promoter region of NRAMP1 and D2S1471, and a microsatellite marker approximately 130-kb downstream of NRAMP1 were examined. The allelic and genotypic frequencies for each polymorphism were compared in case patients and control subjects. No allelic association was identified between the NRAMP1 alleles and typhoid fever susceptibility. In addition, neither homozygotes nor heterozygotes for any NRAMP1 variants were at increased risk of typhoid fever.

Alleles↗

PubMed2001

Cellular stress and injury responses in the brains of adult Vietnamese patients with fatal Plasmodium falciparum malaria.

Immunohistochemical techniques have been used to investigate specific patterns of potentially reversible cellular injury, DNA damage, and apoptosis in the brainstems of Vietnamese patients who died of severe Plasmodium falciparum malaria. The degree and pattern of neuronal and glial stress responses were compared between patients with cerebral and non-cerebral malaria (CM), and appropriate non-malaria infected controls. The following markers were examined: (i) heat shock protein 70 (HSP70), for reversible injury; (ii) heme oxygenase-1, for oxidative stress; (iii & iv) two DNA-repair proteins, poly(ADP) ribose polymerase (PARP) and DNA-dependent protein kinase catalytic subunit; (v) poly(ADP) ribose, an end-product of PARP activity; and (vi) caspase-3-active, for apoptosis. Stress responses were found in a range of cell types as reflected by the widespread expression of HSP70. Oxidative stress predominated in the vicinity of vessels and haemorrhages. Some degree of DNA damage was found in the majority of malaria patients, but the distribution and frequency of the damage was much less than that observed in controls with irreversible neuronal injury. Similarly, caspase-3-active expression, as a measure of apoptosis, was no higher in the majority of malaria patients than the negative control cases, although 40% of CM cases expressed caspase-3-active in a small number of neurones of the pontine nuclei or within swollen axons of the pontocerebellar and corticospinal tracts. In conclusion, cells within the brainstem of all patients who died from severe malaria showed staining patterns indicative of considerable stress response and reversible neuronal injury. There was no evidence for a specific pattern of widespread irreversible cell damage in those patients with cerebral malaria.

Adult↗

PubMed2001

Yersinia pestis pFra shows biovar-specific differences and recent common ancestry with a Salmonella enterica serovar Typhi plasmid.

Population genetic studies suggest that Yersinia pestis, the cause of plague, is a clonal pathogen that has recently emerged from Yersinia pseudotuberculosis. Plasmid acquisition is likely to have been a key element in this evolutionary leap from an enteric to a flea-transmitted systemic pathogen. However, the origin of Y. pestis-specific plasmids remains obscure. We demonstrate specific plasmid rearrangements in different Y. pestis strains which distinguish Y. pestis bv. Orientalis strains from other biovars. We also present evidence for plasmid-associated DNA exchange between Y. pestis and the exclusively human pathogen Salmonella enterica serovar Typhi.

Animals↗

PubMed2001

Serology of typhoid fever in an area of endemicity and its relevance to diagnosis.

Currently, the laboratory diagnosis of typhoid fever is dependent upon either the isolation of Salmonella enterica subsp. enterica serotype Typhi from a clinical sample or the detection of raised titers of agglutinating serum antibodies against the lipopolysaccharide (LPS) (O) or flagellum (H) antigens of serotype Typhi (the Widal test). In this study, the serum antibody responses to the LPS and flagellum antigens of serotype Typhi were investigated with individuals from a region of Vietnam in which typhoid is endemic, and their usefulness for the diagnosis of typhoid fever was evaluated. The antibody responses to both antigens were highly variable among individuals infected with serotype Typhi, and elevated antibody titers were also detected in a high proportion of serum samples from healthy subjects from the community. In-house enzyme-linked immunosorbent assays (ELISAs) for the detection of specific classes of anti-LPS and antiflagellum antibodies were compared with other serologically based tests for the diagnosis of typhoid fever (Widal TO and TH, anti-serotype Typhi immunoglobulin M [IgM] dipstick, and IDeaL TUBEX). At a specificity of > or =0.93, the sensitivities of the different tests were 0.75, 0.55, and 0.52 for the anti-LPS IgM, IgG, and IgA ELISAs, respectively; 0.28 for the antiflagellum IgG ELISA; 0.47 and 0.32 for the Widal TO and TH tests, respectively; and 0.77 for the anti-serotype Typhi IgM dipstick assay. The specificity of the IDeaL TUBEX was below 0.90 (sensitivity, 0.87; specificity, 0.76). The serological assays based on the detection of IgM antibodies against either serotype Typhi LPS (ELISA) or whole bacteria (dipstick) had a significantly higher sensitivity than the Widal TO test when used with a single acute-phase serum sample (P < or = 0.007). These tests could be of use for the diagnosis of typhoid fever in patients who have clinical typhoid fever but are culture negative or in regions where bacterial culturing facilities are not available.

Adolescent↗

PubMed2000

Genes of the class II and class III major histocompatibility complex are associated with typhoid fever in Vietnam.

The influence of genes of the major histocompatibility complex (MHC) class II and class III loci on typhoid fever susceptibility was investigated. Individuals with blood culture-confirmed typhoid fever and control subjects from 2 distinct geographic locations in southern Vietnam were genotyped for HLA-DRB1 and HLA-DQB1 alleles, the gene that encodes tumor necrosis factor (TNF)-alpha (TNFA [-238] and TNFA [-308]), the gene that encodes lymphotoxin-alpha, and alleles of the TNF-alpha microsatellite. HLA-DRB1*0301/6/8, HLA-DQB1*0201-3, and TNFA*2 (-308) were associated with susceptibility to typhoid fever, whereas HLA-DRB1*04, HLA-DQB1*0401/2, and TNFA*1 (-308) were associated with disease resistance. The frequency of all possible haplotypes of the 3 individually associated loci were estimated and were found to be significantly different in typhoid case patients and control subjects (chi2=55.56, 32 df; P=.006). Haplotypes that were either protective (TNFA*1 [-308].DRB1*04) or predisposed individuals to typhoid fever (TNFA*2 [-308].DRB1*0301) were determined. This report identifies a genetic association in humans between typhoid fever and MHC class II and III genes.

Alleles↗

PubMed2000

Blood-brain barrier function in cerebral malaria and CNS infections in Vietnam.

BACKGROUND: The intraerythrocytic parasite Plasmodium falciparum induces the life-threatening neurologic syndrome of cerebral malaria (CM) from within cerebral blood vessels, without entering the brain parenchyma. OBJECTIVES: 1) To assess the use of CSF as an indicator of specific pathologic processes occurring in the brain during CM; 2) to compare this with other neurologic and infectious diseases to understand the distinct pathogenic features of CM; 3) to test the hypothesis that CM involves a specific functional breakdown of the blood-brain barrier (BBB). METHODS: 1) Radial immunodiffusion assays to detect albumin and IgG in matched plasma and CSF samples as indicators of BBB integrity and intrathecal IgG production; and 2) ELISA for soluble intracellular adhesion molecule-1 and sE-selectin, the cytokines tumor necrosis factor-alpha and transforming growth factor-beta1, and the matrix metalloproteinase MMP-9, to detect cellular activation and inflammatory responses within the brain. RESULTS: Albumin and IgG indices implied only minimal degree of BBB breakdown in a few cases of CM, with most remaining within the normal range. In contrast, cryptococcal, tubercular, and acute bacterial meningitis produced detectable changes in the composition of the CSF and evidence of BBB breakdown. CONCLUSIONS: CM appears to involve only subtle functional changes in BBB integrity with minimal intraparenchymal inflammatory responses compared with other neurologic infections. This focuses attention on local events within and around the cerebral microvasculature in CM, rather than indicating widespread parenchymal disease.

Adolescent↗

PubMed2000

Effects of dopamine and epinephrine infusions on renal hemodynamics in severe malaria and severe sepsis.

OBJECTIVE: To describe and compare the effects of dopamine and epinephrine in various doses on renal hemodynamics and oxygen transport in patients with severe malaria and severe sepsis. DESIGN: Prospective, controlled, crossover trial. SETTING: The intensive care unit of an infectious diseases hospital in Viet Nam. PATIENTS: Fourteen patients with severe falciparum malaria and five with severe sepsis. INTERVENTIONS: In an open, crossover design, we observed the effects on renal and systemic hemodynamics and oxygen transport of separate stepped infusions of epinephrine and dopamine. We measured renal blood flow (RBF) and cardiac output by the thermodilution method using fluoroscopically guided catheters. Creatinine clearance at each time point was calculated from the renal plasma flow and the renal arteriovenous difference in plasma creatinine. MEASUREMENTS AND MAIN RESULTS: Dopamine at a "renal" dose (2.5 microg/kg/min) was associated with a mean (95% confidence interval) fractional increase in the absolute renal blood flow index (RBFI) of 37% (13% to 61%) and in RBF as a fraction of cardiac output (RBF/CO) of 35% (10% to 59%; p = .007 and p = .014, respectively). The consequent 39% (14% to 64%) increase in renal oxygen supply (p = .002) was accompanied by a 32% (20% to 44%) decrease in the renal oxygen extraction ratio (p = .0003), leading to no net change in renal oxygen consumption. At higher doses (10 microg/kg/min), both RBF and RBF/CO were not significantly different from baseline values and decreased further as the dose was reduced again. There was no obvious explanation for this hysteresis. There was no change in renal oxygen consumption throughout the study. Because lactic acidosis developed, epinephrine was only given to eight of the 19 patients, and the full stepped epinephrine infusion was given to four patients. Epinephrine infusion was associated, both in absolute terms and when compared with dopamine, with a significant increase in renal vascular resistance (p = .0008 and .0005, respectively), a decrease in RBF/CO (p = .002 and .03), and a compensatory increase in the renal oxygen extraction ratio (p = .005 and .0001). RBFI and renal oxygen consumption remained constant throughout the epinephrine infusion profile. Neither epinephrine nor dopamine significantly affected creatinine clearance or urine output. Twelve patients (63%) were in established renal failure (plasma creatinine, >3 mg/dL) at the time of the study, although the presence or absence of renal failure did not significantly influence the effects of the study drugs. However, overall, the presence of renal failure was associated with a lower mean renal oxygen consumption, a lower mean renal oxygen consumption as a fraction of systemic oxygen consumption, and a higher mean renal vascular resistance. CONCLUSION: Although dopamine increased and epinephrine decreased fractional renal blood flow, there was no evidence that either drug produced either a beneficial or a deleterious effect on renal oxygen metabolism or function at any of the doses investigated.

Adult↗

PubMed2000

The pathophysiologic and prognostic significance of acidosis in severe adult malaria.

OBJECTIVE: To investigate the pathophysiology and prognostic significance of acidosis in severe adult malaria. DESIGN: Cohort study. SETTING: The intensive care unit of an infectious diseases hospital in southern Vietnam. PATIENTS: Three hundred forty-six consecutive adult patients with severe falciparum malaria. INTERVENTIONS: Measurements of baseline venous lactate and pyruvate concentrations and an extensive range of clinical and laboratory variables were made, and patients were followed up carefully until death or discharge from the hospital. Admission arterial blood pH and gas tensions were recorded in 296 patients, and hepatic venous sampling was done in 12 patients. MEASUREMENTS AND MAIN RESULTS: Overall, 198 (67%) patients were acidotic (standard base deficit [SBD], >3.3 mmol/L [n = 196], or arterial Pco2, >45 torr [6 kPa] [n = 3]). Hyperlactatemia (plasma lactate, >4 mmol/L) occurred in 120 (35%) of the 346 patients and was associated significantly with acidosis (p < .0001). The hepatosplanchnic lactate extraction ratio was negatively correlated with mixed venous plasma lactate (r2 = .50; p = .006). Hyperlactatemia, metabolic acidosis (SBD, >3.3), and acidemia (pH <7.35) were strongly positively associated with a fatal outcome (relative risks [95% confidence interval], 4.3 [range, 1.8-10.6], 5.0 [range, 3.0-8.1], and 2.7 [range, 1.8-4.1], respectively). The SBD was the single best clinical or laboratory predictor of fatal outcome. The overall median lactate/pyruvate ratio was raised at 30.6 (range, 20.6-62.3; normal range, <15), suggesting hypoxia and anaerobic glycolysis, and was significantly higher in fatal cases (p < .0001). In an additive multivariate model, the two main independent contributors to metabolic acidosis were plasma creatinine, as a measure of renal dysfunction, and venous plasma lactate, together accounting for 63% of the variance in SBD. In univariate analyses, they contributed 29% and 38%, respectively. CONCLUSIONS: These results confirm the importance of acidosis in the pathophysiology of severe adult malaria and suggest a multifactorial origin involving tissue hypoxia, liver dysfunction, and impaired renal handling of bicarbonate.

Acidosis↗

PubMed2000

Nasal carriage in Vietnamese children of Streptococcus pneumoniae resistant to multiple antimicrobial agents.

Resistance to antimicrobial agents in Streptococcus pneumoniae is increasing rapidly in many Asian countries. There is little recent information concerning resistance levels in Vietnam. A prospective study of pneumococcal carriage in 911 urban and rural Vietnamese children, of whom 44% were nasal carriers, was performed. Carriage was more common in children <5 years old than in those >/=5 years old (192 of 389 [49.4%] versus 212 of 522 [40.6%]; P, 0.01). A total of 136 of 399 isolates (34%) had intermediate susceptibility to penicillin (MIC, 0.1 to 1 mg/liter), and 76 of 399 isolates (19%) showed resistance (MIC, >1.0 mg/liter). A total of 54 of 399 isolates (13%) had intermediate susceptibility to ceftriaxone, and 3 of 399 isolates (1%) were resistant. Penicillin resistance was 21.7 (95% confidence interval, 7.0 to 67.6) times more common in urban than in rural children (35 versus 2%; P, <0.001). More than 40% of isolates from urban children were also resistant to erythromycin, trimethoprim-sulfamethoxazole, chloramphenicol, and tetracycline. Penicillin resistance was independently associated with an urban location when the age of the child was controlled for. Multidrug resistance (resistance to three or more antimicrobial agent groups) was present in 32% of isolates overall but in 39% of isolates with intermediate susceptibility to penicillin and 86% of isolates with penicillin resistance. The predominant serotypes of the S. pneumoniae isolates were 19, 23, 14, 6, and 18. Almost half of the penicillin-resistant isolates serotyped were serotype 23, and these isolates were often multidrug resistant. This study suggests that resistance to penicillin and other antimicrobial agents is common in carriage isolates of S. pneumoniae from children in Vietnam.

Adolescent↗