Value of lipocalin 2 as a potential biomarker for bacterial meningitis

OBJECTIVES

Central nervous system (CNS) infections are common causes of morbidity and mortality worldwide. We aimed to discover protein biomarkers that could rapidly and accurately identify the likely cause of the infections, essential for clinical management and improving outcome.

METHODS

We applied liquid chromatography tandem mass spectrometry on 45 cerebrospinal fluid (CSF) samples from a cohort of adults with and without CNS infections to discover potential diagnostic biomarkers. We then validated the diagnostic performance of a selected biomarker candidate in an independent cohort of 364 consecutively treated adults with CNS infections admitted to a referral hospital in Vietnam.

RESULTS

In the discovery cohort, we identified lipocalin 2 (LCN2) as a potential biomarker of bacterial meningitis (BM) other than tuberculous meningitis. The analysis of the validation cohort showed that LCN2 could discriminate BM from other CNS infections (including tuberculous meningitis, cryptococcal meningitis and virus/antibody-mediated encephalitis), with sensitivity of 0.88 (95% confident interval (CI), 0.77-0.94), specificity of 0.91 (95% CI, 0.88-0.94) and diagnostic odds ratio of 73.8 (95% CI, 31.8-171.4). LCN2 outperformed other CSF markers (leukocytes, glucose, protein and lactate) commonly used in routine care worldwide. The combination of LCN2, CSF leukocytes, glucose, protein and lactate resulted in the highest diagnostic performance for BM (area under the receiver operating characteristics curve, 0.96; 95% CI, 0.93-0.99). Data are available via ProteomeXchange with identifier PXD020510.

CONCLUSIONS

LCN2 is a sensitive and specific biomarker for discriminating BM from a broad spectrum of other CNS infections. A prospective study is needed to assess the diagnostic utility of LCN2 in the diagnosis and management of CNS infections.

Triple artemisinin-based combination therapies versus artemisinin-based combination therapies for uncomplicated Plasmodium falciparum malaria: a multicentre, open-label, randomised clinical trial

BACKGROUND

Artemisinin and partner-drug resistance in Plasmodium falciparum are major threats to malaria control and elimination. Triple artemisinin-based combination therapies (TACTs), which combine existing co-formulated ACTs with a second partner drug that is slowly eliminated, might provide effective treatment and delay emergence of antimalarial drug resistance.

METHODS

In this multicentre, open-label, randomised trial, we recruited patients with uncomplicated P falciparum malaria at 18 hospitals and health clinics in eight countries. Eligible patients were aged 2-65 years, with acute, uncomplicated P falciparum malaria alone or mixed with non-falciparum species, and a temperature of 37·5°C or higher, or a history of fever in the past 24 h. Patients were randomly assigned (1:1) to one of two treatments using block randomisation, depending on their location: in Thailand, Cambodia, Vietnam, and Myanmar patients were assigned to either dihydroartemisinin-piperaquine or dihydroartemisinin-piperaquine plus mefloquine; at three sites in Cambodia they were assigned to either artesunate-mefloquine or dihydroartemisinin-piperaquine plus mefloquine; and in Laos, Myanmar, Bangladesh, India, and the Democratic Republic of the Congo they were assigned to either artemether-lumefantrine or artemether-lumefantrine plus amodiaquine. All drugs were administered orally and doses varied by drug combination and site. Patients were followed-up weekly for 42 days. The primary endpoint was efficacy, defined by 42-day PCR-corrected adequate clinical and parasitological response. Primary analysis was by intention to treat. A detailed assessment of safety and tolerability of the study drugs was done in all patients randomly assigned to treatment. This study is registered at ClinicalTrials.gov, NCT02453308, and is complete.

FINDINGS

Between Aug 7, 2015, and Feb 8, 2018, 1100 patients were given either dihydroartemisinin-piperaquine (183 [17%]), dihydroartemisinin-piperaquine plus mefloquine (269 [24%]), artesunate-mefloquine (73 [7%]), artemether-lumefantrine (289 [26%]), or artemether-lumefantrine plus amodiaquine (286 [26%]). The median age was 23 years (IQR 13 to 34) and 854 (78%) of 1100 patients were male. In Cambodia, Thailand, and Vietnam the 42-day PCR-corrected efficacy after dihydroartemisinin-piperaquine plus mefloquine was 98% (149 of 152; 95% CI 94 to 100) and after dihydroartemisinin-piperaquine was 48% (67 of 141; 95% CI 39 to 56; risk difference 51%, 95% CI 42 to 59; p<0·0001). Efficacy of dihydroartemisinin-piperaquine plus mefloquine in the three sites in Myanmar was 91% (42 of 46; 95% CI 79 to 98) versus 100% (42 of 42; 95% CI 92 to 100) after dihydroartemisinin-piperaquine (risk difference 9%, 95% CI 1 to 17; p=0·12). The 42-day PCR corrected efficacy of dihydroartemisinin-piperaquine plus mefloquine (96% [68 of 71; 95% CI 88 to 99]) was non-inferior to that of artesunate-mefloquine (95% [69 of 73; 95% CI 87 to 99]) in three sites in Cambodia (risk difference 1%; 95% CI -6 to 8; p=1·00). The overall 42-day PCR-corrected efficacy of artemether-lumefantrine plus amodiaquine (98% [281 of 286; 95% CI 97 to 99]) was similar to that of artemether-lumefantrine (97% [279 of 289; 95% CI 94 to 98]; risk difference 2%, 95% CI -1 to 4; p=0·30). Both TACTs were well tolerated, although early vomiting (within 1 h) was more frequent after dihydroartemisinin-piperaquine plus mefloquine (30 [3·8%] of 794) than after dihydroartemisinin-piperaquine (eight [1·5%] of 543; p=0·012). Vomiting after artemether-lumefantrine plus amodiaquine (22 [1·3%] of 1703) and artemether-lumefantrine (11 [0·6%] of 1721) was infrequent. Adding amodiaquine to artemether-lumefantrine extended the electrocardiogram corrected QT interval (mean increase at 52 h compared with baseline of 8·8 ms [SD 18·6] vs 0·9 ms [16·1]; p<0·01) but adding mefloquine to dihydroartemisinin-piperaquine did not (mean increase of 22·1 ms [SD 19·2] for dihydroartemisinin-piperaquine vs 20·8 ms [SD 17·8] for dihydroartemisinin-piperaquine plus mefloquine; p=0·50).

INTERPRETATION

Dihydroartemisinin-piperaquine plus mefloquine and artemether-lumefantrine plus amodiaquine TACTs are efficacious, well tolerated, and safe treatments of uncomplicated P falciparum malaria, including in areas with artemisinin and ACT partner-drug resistance.

FUNDING

UK Department for International Development, Wellcome Trust, Bill & Melinda Gates Foundation, UK Medical Research Council, and US National Institutes of Health.

Determinants of dihydroartemisinin-piperaquine treatment failure in Plasmodium falciparum malaria in Cambodia, Thailand, and Vietnam: a prospective clinical, pharmacological, and genetic study

BACKGROUND

The emergence and spread of resistance in Plasmodium falciparum malaria to artemisinin combination therapies in the Greater Mekong subregion poses a major threat to malaria control and elimination. The current study is part of a multi-country, open-label, randomised clinical trial (TRACII, 2015-18) evaluating the efficacy, safety, and tolerability of triple artemisinin combination therapies. A very high rate of treatment failure after treatment with dihydroartemisinin-piperaquine was observed in Thailand, Cambodia, and Vietnam. The immediate public health importance of our findings prompted us to report the efficacy data on dihydroartemisinin-piperaquine and its determinants ahead of the results of the overall trial, which will be published later this year.

METHODS

Patients aged between 2 and 65 years presenting with uncomplicated P falciparum or mixed species malaria at seven sites in Thailand, Cambodia, and Vietnam were randomly assigned to receive dihydroartemisinin-piperaquine with or without mefloquine, as part of the TRACII trial. The primary outcome was the PCR-corrected efficacy at day 42. Next-generation sequencing was used to assess the prevalence of molecular markers associated with artemisinin resistance (kelch13 mutations, in particular Cys580Tyr) and piperaquine resistance (plasmepsin-2 and plasmepsin-3 amplifications and crt mutations). This study is registered with ClinicalTrials.gov, number NCT02453308.

FINDINGS

Between Sept 28, 2015, and Jan 18, 2018, 539 patients with acute P falciparum malaria were screened for eligibility, 292 were enrolled, and 140 received dihydroartemisinin-piperaquine. The overall Kaplan-Meier estimate of PCR-corrected efficacy of dihydroartemisinin-piperaquine at day 42 was 50·0% (95% CI 41·1-58·3). PCR-corrected efficacies for individual sites were 12·7% (2·2-33·0) in northeastern Thailand, 38·2% (15·9-60·5) in western Cambodia, 73·4% (57·0-84·3) in Ratanakiri (northeastern Cambodia), and 47·1% (33·5-59·6) in Binh Phuoc (southwestern Vietnam). Treatment failure was associated independently with plasmepsin2/3 amplification status and four mutations in the crt gene (Thr93Ser, His97Tyr, Phe145Ile, and Ile218Phe). Compared with the results of our previous TRACI trial in 2011-13, the prevalence of molecular markers of artemisinin resistance (kelch13 Cys580Tyr mutations) and piperaquine resistance (plasmepsin2/3 amplifications and crt mutations) has increased substantially in the Greater Mekong subregion in the past decade.

INTERPRETATION

Dihydroartemisinin-piperaquine is not treating malaria effectively across the eastern Greater Mekong subregion. A highly drug-resistant P falciparum co-lineage is evolving, acquiring new resistance mechanisms, and spreading. Accelerated elimination of P falciparum malaria in this region is needed urgently, to prevent further spread and avoid a potential global health emergency.

FUNDING

UK Department for International Development, Wellcome Trust, Bill & Melinda Gates Foundation, Medical Research Council, and National Institutes of Health.

Non-Typhoidal Salmonella Colonization in Chickens and Humans in the Mekong Delta of Vietnam

Salmonellosis is a public health concern in both the developed and developing countries. Although the majority of human non‐typhoidal Salmonella enterica (NTS) cases are the result of foodborne infections or person‐to‐person transmission, NTS infections may also be acquired by environmental and occupational exposure to animals. While a considerable number of studies have investigated the presence of NTS in farm animals and meat/carcasses, very few studies have investigated the risk of NTS colonization in humans as a result of direct animal exposure. We investigated asymptomatic NTS colonization in 204 backyard chicken farms, 204 farmers and 306 matched individuals not exposed to chicken farming, in southern Vietnam. Pooled chicken faeces, collected using boot or handheld swabs on backyard chicken farms, and rectal swabs from human participants were tested. NTS colonization prevalence was 45.6%, 4.4% and 2.6% for chicken farms, farmers and unexposed individuals, respectively. Our study observed a higher prevalence of NTS colonization among chicken farmers (4.4%) compared with age‐, sex‐ and location‐ matched rural and urban individuals not exposed to chickens (2.9% and 2.0%). A total of 164 chicken NTS strains and 17 human NTS strains were isolated, and 28 serovars were identified. Salmonella Weltevreden was the predominant serovar in both chickens and humans. NTS isolates showed resistance (20–40%) against tetracycline, chloramphenicol, sulfamethoxazole‐trimethoprim and ampicillin. Our study reflects the epidemiology of NTS colonization in chickens and humans in the Mekong delta of Vietnam and emphasizes the need of larger, preferably longitudinal studies to study the transmission dynamics of NTS between and within animal and human host populations.

Highly Pathogenic Avian Influenza Virus A/H5N1 Infection in Vaccinated Meat Duck Flocks in the Mekong Delta of Vietnam

We investigated episodes of suspected highly pathogenic avian influenza (HPAI)-like illness among 12 meat duck flocks in two districts in Tien Giang province (Mekong Delta, Vietnam) in November 2013. In total, duck samples from 8 of 12 farms tested positive for HPAI virus subtype A/haemagglutinin 5 and neuraminidase 1 (H5N1) by real-time RT-PCR. Sequencing results confirmed clade of 2.3.2.1.c as the cause of the outbreaks. Most (7/8) laboratory-confirmed positive flocks had been vaccinated with inactivated HPAI H5N1 clade 2.3.4 vaccines <6 days prior to onset of clinical signs. A review of vaccination data in relation to estimated production in the area suggested that vaccination efforts were biased towards larger flocks and that vaccination coverage was low [21.2% ducks vaccinated with two shots (range by district 7.4-34.9%)]. The low-coverage data, the experimental evidence of lack of cross-protection conferred by the currently used vaccines based on clade 2.3.4 together with the short lifespan of meat duck flocks (60-70 days), suggest that vaccination is not likely to be effective as a tool for control of H5N1 infection in meat duck flocks in the area.

A Randomized Comparison of Chloroquine Versus Dihydroartemisinin-Piperaquine for the Treatment of Plasmodium vivax Infection in Vietnam

A total of 128 Vietnamese patients with symptomatic Plasmodium vivax mono-infections were enrolled in a prospective, open-label, randomized trial to receive either chloroquine or dihydroartemisinin–piperaquine (DHA-PPQ). The proportions of patients with adequate clinical and parasitological responses were 47% in the chloroquine arm (31 of 65 patients) and 66% in the DHA-PPQ arm (42 of 63 patients) in the Kaplan–Meier intention-to-treat analysis (absolute difference 19%, 95% confidence interval = 0–37%), thus establishing non-inferiority of DHA-PPQ. Fever clearance time (median 24 versus 12 hours, P = 0.02), parasite clearance time (median 36 versus 18 hours, P < 0.001), and parasite clearance half-life (mean 3.98 versus 1.80 hours, P < 0.001) were all significantly shorter in the DHA-PPQ arm. All cases of recurrent parasitemia in the chloroquine arm occurred from day 33 onward, with corresponding whole blood chloroquine concentration lower than 100 ng/mL in all patients. Chloroquine thus remains efficacious for the treatment of P. vivax malaria in southern Vietnam, but DHA-PPQ provides more rapid symptomatic and parasitological recovery.

High levels of antimicrobial resistance among escherichia coli isolates from livestock farms and synanthropic rats and shrews in the Mekong Delta of Vietnam

In Mekong Delta farms (Vietnam), antimicrobials are extensively used, but limited data are available on levels of antimicrobial resistance (AMR) among Escherichia coli isolates. We performed a structured survey of AMR in E. coli isolates (n = 434) from 90 pig, chicken, and duck farms. The results were compared with AMR among E. coli isolates (n = 234) from 66 small wild animals (rats and shrews) trapped on farms and in forests and rice fields. The isolates were susceptibility tested against eight antimicrobials. E. coli isolates from farmed animals were resistant to a median of 4 (interquartile range [IQR], 3 to 6) antimicrobials versus 1 (IQR, 1 to 2) among wild mammal isolates (P < 0.001). The prevalences of AMR among farmed species isolates (versus wild animals) were as follows: tetracycline, 84.7% (versus 25.6%); ampicillin, 78.9% (versus 85.9%); trimethoprim-sulfamethoxazole, 52.1% (versus 18.8%); chloramphenicol, 39.9% (versus 22.5%); amoxicillin-clavulanic acid, 36.6% (versus 34.5%); and ciprofloxacin, 24.9% (versus 7.3%). The prevalence of multidrug resistance (MDR) (resistance against three or more antimicrobial classes) among pig isolates was 86.7% compared to 66.9 to 72.7% among poultry isolates. After adjusting for host species, MDR was ∼8 times greater among isolates from wild mammals trapped on farms than among those trapped in forests/rice fields (P < 0.001). Isolates were assigned to unique profiles representing their combinations of susceptibility results. Multivariable analysis of variance indicated that AMR profiles from wild mammals trapped on farms and those from domestic animals were more alike (R(2) range, 0.14 to 0.30) than E. coli isolates from domestic animals and mammals trapped in the wild (R(2) range, 0.25 to 0.45). The results strongly suggest that AMR on farms is a key driver of environmental AMR in the Mekong Delta.

Recent avian influenza virus A/H5N1 evolution in vaccinated and unvaccinated poultry from farms in Southern Vietnam, January-March 2010

We report 15 new avian influenza virus A/H5N1 haemagglutinin (HA) sequences sampled from visibly sick domestic poultry in southern Vietnam, between 1 January 2010 and 6 March 2010. These HA sequences form a new sub-clade of the clade 1 H5N1 viruses that have been circulating in Vietnam since 2003/2004. The viruses are characterized by a change from isoleucine to valine at position 514 (I514V) and are 1.8% divergent at the nucleotide level from HA sequences sampled in Vietnam in 2007. Five new amino acid changes were observed at previously identified antigenic sites, and three were located within structural elements of the receptor-binding domain. One new mutation removed a potential N-linked glycosylation site, and a methionine insertion was observed in one virus at the polybasic cleavage site. Five of these viruses were sampled from farms where poultry were vaccinated against H5N1, but there was no association between observed amino acid changes and flock vaccination status. Despite the current lack of evidence for antigenic drift or immune escape in Vietnamese H5N1 viruses, continued surveillance remains a high priority.

Brain tumours in Ho Chi Minh City

A series of 65 intracranial tumours operated on, and followed by, the same surgical team during 7 years is presented as a retrospective analysis (1987-1994). Among these patients, only 38 had a diagnosis based upon computed tomography (CT) scan because it was not until 1991 that the first CT scanner was set up in Ho Chi Minh City. Many patients were drowsy or comatose prior to operation due to lack of specialists' intervention or tardy diagnosis and evacuation from remote provincial hospitals. All operations were satisfactory despite the lack of many essential instruments. The histological diagnosis followed the classification proposed by Zulch KJ.(1) Intratumoural calcification has in no case been seen on X-rays or on histological specimens. Operative mortality rate was nil. Although not all the patients with malignant tumours could be followed up, the data available concerning their survival time and the quality of life seems similar to that observed in other reports.

Expression of immune responsive genes in cell lines from two different Anopheline species

Malaria infection results in increased expression of immune responsive genes, including those encoding antimicrobial peptides such as Gambicin (Gam1) and Cecropin A (Cec1). Understanding how these genes are regulated will provide insights how the mosquito immune system is activated by Plasmodium. We previously have shown that Cec1 was primarily regulated by the Imd-Relish (REL2) pathway in the Anopheles gambiae Sua1B cell line. We show here that expression of Defensin A (Def1) and Gam1 was reduced after RNA interference against components of the Imd-REL2 pathway in An. gambiae cell lines. Interestingly, promoter reporters of these antimicrobial peptides were expressed at very low level in the cell line MSQ43 from Anopheles stephensi. Surprisingly, over-expression of either NF-kappaB transcription factor REL1 or REL2 alone is sufficient to induce the expression of Cec1, Gam1 and Def1. These results suggest that expression of these antimicrobial peptides (AMP) in vivo may be regulated by both the Toll and Imd pathways. We also show here for the first time that Tep4, a gene encoding a thioester containing protein, is regulated by REL2. Taken together, these results suggest that there are significant overlaps of genes regulated by the Toll-Rel1 and Imd-Rel2 pathways. Further, the different expression patterns in two different Anopheline cell lines provide a platform to identify other key positive and negative regulators of the antimicrobial peptide genes.

Characterization of RNA interference in an Anopheles gambiae cell line

Introduction of double stranded RNA into invertebrate cells often results in posttranscriptional silencing of target genes through a mechanism termed RNA interference (RNAi). Double-stranded RNA is cleaved by an RNAse III-like enzyme, termed dicer, to small interfering RNAs (siRNAs). In Drosophila, these siRNAs are incorporated in the RNA induced silencing complex (RISC) and mediate degradation of target mRNA. The RISC complex contains members of Argonaute (Ago) family of proteins. We show here that RNAi in a hemocyte cell line of Anopheles gambiae, the principal malaria vector in Africa, requires expression of dicer-2, Ago2 and Ago3 proteins. Furthermore, we demonstrate that RNAi in the mosquito does not spread outside of the target region, suggesting that RNA dependent RNA polymerase mediated transitive amplification is absent in the mosquito.

Characterization of three Toll-like genes from mosquito Aedes aegypti

Three Toll-related genes (AeToll1A, AeToll1B and AeToll5) were cloned and characterized from the yellow fever vector mosquito, Aedes aegypti. All three genes exhibited high levels of amino acid sequence similarity with Drosophila melanogaster (Dm)Toll1 and DmTehao (Toll5). AeToll1A and AeToll1B are 1124 and 1076 amino acid residues long, respectively. Both contain a carboxyl extension downstream of the Toll/interleukin-1 receptor (TIR) domain. AeToll5 is 1007 residues long and, like DmTehao, lacks the carboxyl terminal extension. Expression of these three genes was examined throughout development and after immune challenge. Both AeToll1A and AeToll5, like their Drosophila counterparts, activate transcription of drosomycin promoter in both Aedes and Drosophila cell lines. Deletion of the carboxyl extension of AeToll1A did not result in a further elevated level of the antifungal response. The intracellular signalling process appears to be species specific based on two observations. (1) DmToll is completely inactive in an Aedes cell line, suggesting a higher specificity requirement for DmToll in the intracellular signalling process. (2) Only one of three amino acid residues essential for DmToll function is required for AeToll1A function.

The PDZ domain of the SpoIVB serine peptidase facilitates multiple functions

During spore formation in Bacillus subtilis, the SpoIVB protein is a critical component of the sigma(K) regulatory checkpoint. SpoIVB has been shown to be a serine peptidase that is synthesized in the spore chamber and which self-cleaves, releasing active forms. These forms can signal proteolytic processing of the transcription factor sigma(K) in the outer mother cell chamber of the sporulating cell. This forms the basis of the sigma(K) checkpoint and ensures accurate sigma(K)-controlled gene expression. SpoIVB has also been shown to activate a second distinct process, termed the second function, which is essential for the formation of heat-resistant spores. In addition to the serine peptidase domain, SpoIVB contains a PDZ domain. We have altered a number of conserved residues in the PDZ domain by site-directed mutagenesis and assayed the sporulation phenotype and signaling properties of mutant SpoIVB proteins. Our work has revealed that the SpoIVB PDZ domain could be used for up to four distinct processes, (i) targeting of itself for trans proteolysis, (ii) binding to the protease inhibitor BofC, (iii) signaling of pro-sigma(K) processing, and (iv) signaling of the second function of SpoIVB.

First cases of disseminated penicilliosis marneffei infection among patients with acquired immunodeficiency syndrome in Vietnam

To our knowledge, this is the first report of penicilliosis marneffei among patients with acquired immunodeficiency syndrome (AIDS) in Vietnam. The 4 patients we studied were from Ho Chi Minh City and the provinces of Tay Ninh, Dong Nai, and Kon Tum. In 2 patients, the infections were fatal.

Characterization of Bacillus species used for oral bacteriotherapy and bacterioprophylaxis of gastrointestinal disorders

Bacillus subtilis spores are being used for oral bacteriotherapy and bacterioprophylaxis of gastrointestinal disorders in both humans and animals. Since B. subtilis is an aerobic saprophyte, how spores may benefit the gut microbiota is an intriguing question, since other probiotics such as Lactobacillus spp. which colonize the gut are anerobes. As a first step in understanding the potential effects of ingesting spores, we have characterized five commercial products. An extensive biochemical, physiological, and phylogenetic analysis has revealed that four of these products are mislabeled. Moreover, four of these products showed high levels of antibiotic resistance.

Cytochalasin B modulation of Caco-2 tight junction barrier: role of myosin light chain kinase

The intracellular mechanisms that mediate cytochalasin-induced increase in intestinal epithelial tight junction (TJ) permeability are unclear. In this study, we examined the involvement of myosin light chain kinase (MLCK) in this process, using the filter-grown Caco-2 intestinal epithelial monolayers. Cytochalasin B (Cyto B) (5 microg/ml) produced an increase in Caco-2 MLCK activity, which correlated with the increase in Caco-2 TJ permeability. The inhibition of Cyto B-induced MLCK activation prevented the increase in Caco-2 TJ permeability. Additionally, myosin-Mg(2+)-ATPase inhibitor and metabolic inhibitors (which inhibit MLCK induced actin-myosin contraction) also prevented the Cyto B-induced increase in Caco-2 TJ permeability. Cyto B caused a late-phase (15-30 min) aggregation of actin fragments into large actin clumps, which was also inhibited by MLCK inhibitors. Cyto B produced a morphological disturbance of the ZO-1 TJ proteins, visually correlating with the functional increase in Caco-2 TJ permeability. The MLCK and myosin-Mg(2+)-ATPase inhibitors prevented both the functional increase in TJ permeability and disruption of ZO-1 proteins. These findings suggested that Cyto B-induced increase in Caco-2 TJ permeability is regulated by MLCK activation.

BofC negatively regulates SpoIVB-mediated signalling in the Bacillus subtilis sigmaK-checkpoint

The BofC protein acts negatively on intercompartmental signalling of pro-sigma(K) processing in the sigma(K)-checkpoint of Bacillus subtilis. Signalling is brought about by the SpoIVB protein, which is synthesized in the forespore and initiates proteolytic processing of pro-sigmaK to its mature and active form in the opposed mother cell chamber of the developing cell. We have shown here that BofC, like SpoIVB, is secreted across the inner forespore membrane and, from the analysis of a bofC deletion and insertion mutant, is likely to interact with SpoIVB. In the absence of BofC, the amount of SpoIVB found in sporulating cells is substantially reduced, although SpoIVB is still able to activate proteolysis of pro-sigma(K). Conversely, in the absence of SpoIVB, the levels of BofC accumulate suggesting that the fate of each molecule is dependent upon their mutual interaction. Our results suggest that BofC could maintain SpoIVB in a stable but inactive form. Supporting this, we have shown that overproduction of BofC inhibits SpoIVB autoproteolysis and leads to a delay in proteolytic cleavage of pro-sigma(K). Based on our work here, we have proposed a model for BofC's functional role in intercompartmental signalling.

Proteolysis of SpolVB is a critical determinant in signalling of Pro-sigmaK processing in Bacillus subtilis

SpoIVB is essential for intercompartmental signalling in the sigma(K)-checkpoint of Bacillus subtilis. SpoIVB is synthesized in the spore chamber and is the signal which activates proteolytic processing of pro-sigma(K) to its mature and active form sigma(K). We show here that SpoIVB is a serine peptidase of the SA clan. Expression of SpoIVB in Escherichia coli has shown that SpoIVB is able to self-cleave into at least three discrete products, and in vitro studies have shown cleavage in trans. Autoproteolysis of SpoIVB is tightly linked to the initiation of the two developmental functions of this protein, signalling of pro-sigma(K) processing and a yet, uncharacterized, second function which is essential for the formation of heat-resistant spores. In B. subtilis, SpoIVB is synthesized as a zymogen and is subject to two levels of proteolysis. First, autoproteolysis generating intermediate products, at least one of which is proposed to be the active form, followed by processing by one or more enzymes to smaller species. This could provide a mechanism for switching off the active SpoIVB intermediate(s) and suggests a similarity to other proteolytic cascades such as those found in blood coagulation.

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.

Molecular methods for the epidemiological typing of Salmonella enterica serotype Typhi from Hong Kong and Vietnam

A total of 217 and 73 strains of Salmonella enterica serotype Typhi isolated from 1985 to 1997 in Hong Kong and in 2 months of 1989 and 1990 in Vietnam, respectively, were studied. These isolates were typed by plasmid profile analysis, plasmid fingerprinting, ribotyping with PstI, and total DNA fingerprinting with NarI. There appeared to be no major outbreak of typhoid fever in Hong Kong during the study period since there was considerable heterogeneity among the isolates. Isolates from Hong Kong were different from those from Vietnam. Thirty-seven percent of Vietnamese isolates belonged to two predominant clones, with the rest being heterogeneous in nature. Total DNA fingerprinting supplemented with ribotyping could be a reliable and rapid method for epidemiological typing of S. enterica serotype Typhi.

Melioidosis in Southern Vietnam: clinical surveillance and environmental sampling

From 1992-1998, Burkholderia pseudomallei was isolated from only 9 (0.25%) of 3653 cultures of blood from febrile patients admitted to the Centre for Tropical Diseases in Ho Chi Minh City, an infectious disease referral center for southern Vietnam. Soil was sampled from 407 sites in 147 rice fields along the 5 major roads radiating from Ho Chi Minh City. B. pseudomallei was isolated from 73 sites (18%) in 39 rice fields (27%), but only 15 (21%) of the 71 isolates from 9 (6%) of 147 fields were the virulent l-arabinose (ara)-negative biotype. All except 1 of the fields with the ara-negative biotype were close to the homes of the patients with melioidosis. The low incidence of melioidosis in the provinces around Ho Chi Minh City may be explained by the restricted distribution of ara-negative B. pseudomallei in the soil in this area.

Basic fibroblast growth factor stimulates repair of wounded hepatocyte monolayer: modulatory role of protein kinase A and extracellular matrix

The two important repair mechanisms after hepatocyte injury are proliferation and migration of the nearby healthy hepatocytes. Although previous studies have shown that basic fibroblast growth factor (bFGF) levels are markedly elevated after liver injury, the role of bFGF in the repair of the wounded hepatocytes is not well understood. The aim of this study was to delineate the role of bFGF in the repair of the wounded hepatocyte monolayers. Specifically, we examined the role of bFGF in cellular proliferation and migration of hepatocytes with an in vitro wound model. Standardized excisional wounds were created in clone 9 rat hepatocyte monolayers by a razor blade, and the extent of epithelial proliferation and migration was measured. After wound formation, bFGF (30 ng/mL) significantly stimulated proliferation of hepatocytes at the wound margin. bFGF also stimulated the migration of hepatocytes at the wound front. bFGF stimulation of hepatocyte migration correlated with increased formation of actin stress fibers and bFGF-receptor protein level. The bFGF stimulation of hepatocyte migration was abolished by various protein kinase A activating agents including 3-isobutyl-1-methylxanthine, 8-bromoadenosine-3', 5'-cyclic monophosphate, forskolin, and cholera toxin. In addition, protein kinase A activating agents almost completely prevented bFGF-induced actin stress fiber formation in the cells at the wound front. Varying the basement membrane composition of the extracellular matrix had a selective enhancing effect on the basal rates of hepatocyte migration (collagen IV > or = laminin > collagen I > fibronectin > control (plastic)). bFGF treatment resulted in a similar additive increase in hepatocyte migration across all coated surfaces studied. We conclude that bFGF promotes hepatocyte wound repair by stimulating both proliferation and migration of the hepatocyte at the margin of the wound.

Value of a single-tube widal test in diagnosis of typhoid fever in Vietnam

The diagnostic value of an acute-phase single-tube Widal test for suspected typhoid fever was evaluated with 2,000 Vietnamese patients admitted to an infectious disease referral hospital between 1993 and 1998. Test patients had suspected typhoid fever and a blood culture positive for Salmonella typhi (n= 1,400) or Salmonella paratyphi A (n = 45). Control patients had a febrile illness for which another cause was confirmed (malaria [n = 103], dengue [n = 76], or bacteremia due to another microorganism [n = 156] or tetanus (n = 265). An O-agglutinin titer of >/=100 was found in 18% of the febrile controls and 7% of the tetanus patients. Corresponding values for H agglutinins were 8 and 1%, respectively. The O-agglutinin titer was >/=100 in 83% of the blood culture-positive typhoid fever cases, and the H-agglutinin titer was >/=100 in 67%. The disease prevalence in investigated patients in this hospital was 30.8% (95% confidence interval, 26.8 to 35.1%); at this prevalence, an elevated level of H agglutinins gave better positive predictive values for typhoid fever than did O agglutinins. With a cutoff titer of >/=200 for O agglutinin or >/=100 for H agglutinin, the Widal test would diagnose correctly 74% of the blood culture-positive cases of typhoid fever. However, 14% of the positive results would be false-positive, and 10% of the negative results would be false-negative. The Widal test can be helpful in the laboratory diagnosis of typhoid fever in Vietnam if interpreted with care.

Willingness to donate organs and tissues in Vietnam

CONTEXT

Few studies on public attitudes toward organ and tissue donation have been carried out in Asia.

OBJECTIVE

To determine demographic influences on attitudes toward organ and tissue donation in Vietnam.

DESIGN

Face-to-face interviews.

SETTING

Tan Binh District, Ho Chi Minh City, Vietnam.

PARTICIPANTS

Random sample of adults (N = 785).

MAIN OUTCOME MEASURES

Awareness of donation and transplantation, acceptance of organ and tissue donation.

RESULTS

75% of respondents stated they had heard of organ or tissue donation, but only 55% were aware of organ and tissue transplantation taking place in Vietnam. Forty-eight percent of Buddhists and 27.5% of Christians had either no knowledge or incorrect knowledge about their religion's official position toward donation and transplantation. Sixty-four percent stated they would give consent for the donation of their decreased relative's tissues and organs, 66% would themselves become posthumous donors, and 21% to 22% would donate multiple organs and tissues. A significant association was found between respondents' acceptance of organ and tissue donation and their educational level, sex, occupation, and awareness of transplantation. Most respondents stated that their willingness to donate depended on whether other family members agreed. Many noted the importance of preventing commerce in organ and tissue transplantation but were in favor of providing healthcare for the donor's family or monetary incentives as a reward for donating.

CONCLUSION

Nearly two thirds of urban Vietnamese surveyed were willing to donate organs or tissues after death. Their willingness was related to awareness of transplantation, sex, education level, and occupation.

Community-acquired septicaemia in southern Viet Nam: the importance of multidrug-resistant Salmonella typhi

In a prospective study conducted between mid 1993 and 1994, 437 adults and children were admitted with community-acquired septicaemia to an infectious diseases hospital in southern Viet Nam. Gram-negative aerobes accounted for 90% of isolates and were predominantly Salmonella typhi (67%), Sal. para-typhi A (3%), Escherichia coli (10%), and Klebsiella spp. (5%). Other Salmonella spp. (1%), Pseudomonas aeruginosa (1%), Neisseria meningitidis (0.5%) and Haemophilus influenzae (0.2%) were uncommon. Staphylococcus aureus (5.5%) and Streptococcus pneumoniae (2%) were the most common Gram-positive isolates. Patients with enteric fever were younger (median age 16 years, range 1-63) than the other patients (median age 43 years, range 1-88) (P < 0.001) and had a lower mortality rate (0.3% vs. 23%; relative risk 69.5, 95% confidence interval 9.5-507.8; P < 0.0001). Over 70% of the Sal. typhi isolated were multi-drug-resistant, and 4% were resistant to nalidixic acid. Multidrug-resistant Sal. typhi is a major cause of community-acquired septicaemia in Viet Nam.

Quinolone-resistant Salmonella typhi in Viet Nam: molecular basis of resistance and clinical response to treatment

Nalidixic acid-resistant Salmonella typhi (NARST) was first isolated in Viet Nam in 1993. Analysis of the quinolone resistance-determining region of gyrA in 20 NARST isolates by polymerase chain reaction and single-stranded conformational polymorphism yielded two novel patterns: pattern II corresponding to a point mutation at nucleotide 87 Asp-->Gly (n = 17), and pattern III corresponding to a point mutation at nucleotide 83 Ser-->Phe (n = 3). In trials of short-course ofloxacin therapy for uncomplicated typhoid, 117 (78%) of 150 patients were infected with multidrug-resistant S. typhi, 18 (15%) of which were NARST. The median time to fever clearance was 156 hours (range, 30-366 hours) for patients infected with NARST and 84 hours (range, 12-378 hours) for those infected with nalidixic acid-susceptible strains (P < .001). Six (33.3%) of 18 NARST infections required retreatment, whereas 1 (0.8%) of 132 infections due to susceptible strains required retreatment (relative risk = 44; 95% confidence interval = 5.6-345; P < .0001). We recommend that short courses of quinolones not be used in patients infected with NARST.

Design and evaluation of two-phase partition-dissolution method and its use in evaluating artemisinin tablets

A method is described for the assessment of the dissolution behavior of solid dosage forms with a high content of a very water insoluble drug. In this method the dissolved drug is continuously extracted from the aqueous dissolution medium into an organic phase. The reported data on the dissolution of artemisinin show that this method guarantees sink conditions in the aqueous dissolution medium during the total duration of the experiment.

Comparison of ofloxacin and ceftriaxone for short-course treatment of enteric fever

An open, randomized comparison of ofloxacin (200 mg, every 12 h) given orally for 5 days and ceftriaxone (3 g, once daily) given intravenously for 3 days in the treatment of uncomplicated enteric fever was conducted in Ho Chi Minh City, Vietnam. Salmonella paratyphi type A was isolated from six patients. Salmonella typhi was isolated from 41 patients; 63% of these isolates were resistant to multiple antibiotics: ampicillin, chloramphenicol, sulfamethoxazole, trimethoprim, and tetracycline. Of the culture-confirmed cases, treatment with ofloxacin resulted in complete cure of all 22 patients, whereas 18 of 25 patients treated with ceftriaxone were completely cured (P < 0.01). In the ceftriaxone group, there were six acute treatment failures and one relapse. Mean +/- standard deviation fever clearance times were 81 +/- 25 h for ofloxacin and 196 +/- 87 h for ceftriaxone (P < 0.0001). Short-course treatment with oral ofloxacin (5 days) is significantly better than that with ceftriaxone (3 days) and will be of particular benefit in areas where multiresistant strains of S. typhi are encountered.

Comparison of artemisinin suppositories with intravenous artesunate and intravenous quinine in the treatment of cerebral malaria

Seventy-nine comatose cerebral malaria patients given standard supportive treatment were randomized to receive specific antimalarial chemotherapy of intravenous quinine, intravenous artesunate, or artemisinin suppositories. Artesunate and artemisinin reduced peripheral asexual parasitaemia significantly more rapidly than quinine (90% clearance time 16 h, 18.9 h and 34.5 h respectively), but did not significantly reduce the duration of coma or mortality. The rapid lowering of peripheral parasitaemia may not ameliorate complications already present. These results demonstrate that artemisinin suppositories are as effective as artesunate and quinine given intravenously, and have economic and practical advantages for the treatment of severe malaria in areas remote from major medical centres. However, large numbers of patients will need to be studied if differences in mortality between the 3 treatment groups are to be demonstrated.