Patient-centered mobile tuberculosis treatment support tools (TB-TSTs) to improve treatment adherence: A pilot randomized controlled trial exploring feasibility, acceptability and refinement needs

Background

Digital adherence technologies hold promise to improve patient-centered tuberculosis (TB) monitoring, yet few studies have incorporated direct adherence monitoring or assessed patients' experiences with these technologies. We explored acceptability, feasibility, and refinement needs of the TB Treatment Support Tools (TB-TSTs) intervention linking a mobile app, a urine drug metabolite test, and interactive communication with a treatment supporter.

Methods

This pilot study was a parallel-designed single-center randomized controlled trial with exit interviews. Newly diagnosed TB patients were randomized 1:1 using a treatment allocation button in the REDCap software preloaded with a random allocation sequence to usual care or usual care plus the TB-TSTs intervention from a respiratory medicine hospital in the province of Buenos Aires, Argentina and followed for 6-months. Due to the nature of the intervention, blinding to the group allocation could not be achieved for the recruiter or patients. The treatment outcome data extractor was blinded to the group allocation of the participants. Intervention participants used the app to report self-administering medication, potential side effects, submit photos of the urine test, and interact with a treatment supporter. Outcomes were feasibility, acceptability, and treatment outcomes.

Findings

Forty-two patients were enrolled and evenly assigned to each group. Intervention participants submitted 147·2±58 (mean, SD) medication self-administration and 144·5±55 side effect reports out of 180 and 47.5±38·4 photos of the urine test out of 77. Treatment success for usual care was 81% [17/21] and 95% [20/21] for the TB-TSTs intervention. Thirty-three themes were identified within the main categories of motivation, what worked, issues experienced, and recommendations. Participants (n=12) rated it as 'easy to use' (4.57/5), 'would highly recommend to others' (4·43/5) and reported that access to the treatment support was a critical component. Recommendations included adding an alarm, appointment reminders, and off-line functionality.

Interpretation

Findings suggest that the TB-TSTs intervention was feasible and acceptable and further refinement and testing is warranted.

Funding

National Institute of Health K23NR017210.

Mobile Tuberculosis Treatment Support Tools to Increase Treatment Success in Patients with Tuberculosis in Argentina: Protocol for a Randomized Controlled Trial

BACKGROUND

Tuberculosis (TB) is an urgent global health threat and the world's deadliest infectious disease despite being largely curable. A critical challenge is to ensure that patients adhere to the full course of treatment to prevent the continued spread of the disease and development of drug-resistant disease. Mobile health interventions hold promise to provide the required adherence support to improve TB treatment outcomes.

OBJECTIVE

This study aims to evaluate the effectiveness of the TB treatment support tools (TB-TSTs) intervention on treatment outcomes (success and default) and to assess patient and provider perceptions of the facilitators and barriers to TB-TSTs implementation.

METHODS

The TB-TSTs study is an open-label, randomized controlled trial with 2 parallel groups in which 400 adult patients newly diagnosed with TB will be randomly assigned to receive usual care or usual care plus TB-TSTs. Participants will be recruited on a rolling basis from 4 clinical sites in Argentina. The intervention consists of a smartphone progressive web app, a treatment supporter (eg, TB nurse, physician, or social worker), and a direct adherence test strip engineered for home use. Intervention group participants will report treatment progress and interact with a treatment supporter using the app and metabolite urine test strip. The primary outcome will be treatment success. Secondary outcomes will include treatment default rates, self-reported adherence, technology use, and usability. We will assess patients' and providers' perceptions of barriers to implementation and synthesize lessons learned. We hypothesize that the TB-TSTs intervention will be more effective because it allows patients and TB supporters to monitor and address issues in real time and provide tailored support. We will share the results with stakeholders and policy makers.

RESULTS

Enrollment began in November 2020, with a delayed start due to the COVID-19 pandemic, and complete enrollment is expected by approximately July 2022. Data collection and follow-up are expected to be completed 6 months after the last patient is enrolled. Results from the analyses based on the primary end points are expected to be submitted for publication within a year of data collection completion.

CONCLUSIONS

To our knowledge, this randomized controlled trial will be the first study to evaluate a patient-centered remote treatment support strategy using a mobile tool and a home-based direct drug metabolite test. The results will provide robust scientific evidence on the effectiveness, implementation, and adoption of mobile health tools. The findings have broader implications not only for TB adherence but also more generally for chronic disease management and will improve our understanding of how to support patients facing challenging treatment regimens.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04221789; https://clinicaltrials.gov/ct2/show/NCT04221789.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/28094.

Insights from participant engagement with the tuberculosis treatment support tools intervention: Thematic analysis of interactive messages to guide refinement to better meet end user needs

BACKGROUND

Tuberculosis (TB) is a largely curable disease, yet it remains one of the top ten causes of death globally. In response to known challenges to completing the long course of TB treatment, our study team developed the TB treatment support tools (TB-TSTs). The mobile application (app) is comprised of the following main components: 1) tracks treatment progress, 2) provides disease tailored information, 3) interactive communication between patients and treatment supporters, and 4) is linked with a direct adherence drug metabolite test.

OBJECTIVE

The objective of this study was to analyze the interactive communication between the patients and the treatment supporter during the TB-TSTs pilot testing to identify issues and guide intervention refinement.

METHODS

We used mixed methods to analyze the interactive communication data. The study was conducted at a pulmonary disease specialized hospital in Argentina. Of the 42 study participants enrolled in the pilot study, 21 were randomly assigned to use the TB-TSTs for 6-months during their TB treatment. The treatment supporter was a registered nurse from the regional level of the National TB program. We conducted thematic and content analysis of the messages in their original language, Spanish. We assessed the themes over time and by whom initiated the messages.

RESULTS

There were 2561 individual messages sent between the participants and treatment supporter. We identified 19 main themes: 7 were participant and 12 were treatment supporter initiated. Participant themes included missed report rationale, arranging in-person meeting, intervention support, TB treatment progress, disease/treatment questions, side effects and additional support. Treatment supporter themes included missed report inquiry, arranging in-person meeting, introduction and instructions, check-in's, positive reinforcement, treatment progress inquiry, test-strip issues, intervention orientation, initial side-effect check in, follow-up on side effects and photo quality issues. Messages and themes decreased over time with most occurring within the first 2 months of treatment.

CONCLUSIONS

Although there was a decrease in the number of messages and the theme types over the 6-month study participation, treatment adherence support remained needed throughout. Potential solutions are suggested for the main issues and recommendations are being used to guide refinement.

Converting and expanding a mobile support intervention: Focus group and field-testing findings from individuals in active tuberculosis treatment

BACKGROUND

Non-adherence to tuberculosis (TB) treatment jeopardizes the individual's health and contributes to disease transmission and drug resistance. New patient-centered strategies are needed to improve TB treatment outcomes.

PURPOSE

To convert and expand a texting-based intervention into a mobile optimized application (app), evaluate the feasibility of an added self-administered paper-based drug metabolite test, and identify needs and preferences to inform their iterative design.

METHODS

Qualitative methods using focus groups and field testing with patients in active TB treatment were used to gather initial input on the converted intervention design, content and issues using at home test strips to report medication adherence. Seven participants were recruited from an outpatient clinic within a regional public reference hospital specialized in respiratory diseases in Argentina. Thematic analyses were conducted on the transcripts and session notes.

RESULTS

Participants considered interactive communication, access to answers to frequently asked questions, and tracking of progress in treatment as important. Participants reported having many questions and uncertainties at initiation of treatment and emphasized a need for reliable information, assurance and support from both providers and peers. Other suggestions included streamlining the graphical user interface for easier and shorter data entry times and usability.

CONCLUSIONS

Overall feedback from the participants regarding the intervention was positive, reporting that it was useful and relevant, and they were eager to contribute their ideas for improvement and additional functionality. Valuable feedback to improve functionality and meet the needs of end-users were obtained to inform the generation of new design ideas for refinement and testing in a pilot study.

Evaluation of a social protection policy on tuberculosis treatment outcomes: A prospective cohort study

BACKGROUND

Tuberculosis (TB) still represents a major public health problem in Latin America, with low success and high default rates. Poor adherence represents a major threat for TB control and promotes emergence of drug-resistant TB. Expanding social protection programs could have a substantial effect on the global burden of TB; however, there is little evidence to evaluate the outcomes of socioeconomic support interventions. This study evaluated the effect of a conditional cash transfer (CCT) policy on treatment success and default rates in a prospective cohort of socioeconomically disadvantaged patients.

METHODS AND FINDINGS

Data were collected on adult patients with first diagnosis of pulmonary TB starting treatment in public healthcare facilities (HCFs) from 16 health departments with high TB burden in Buenos Aires who were followed until treatment completion or abandonment. The main exposure of interest was the registration to receive the CCT. Other covariates, such as sociodemographic and clinical variables and HCFs' characteristics usually associated with treatment adherence and outcomes, were also considered in the analysis. We used hierarchical models, propensity score (PS) matching, and inverse probability weighting (IPW) to estimate treatment effects, adjusting for individual and health system confounders. Of 941 patients with known CCT status, 377 registered for the program showed significantly higher success rates (82% versus 69%) and lower default rates (11% versus 20%). After controlling for individual and system characteristics and modality of treatment, odds ratio (OR) for success was 2.9 (95% CI 2, 4.3, P < 0.001) and default was 0.36 (95% CI 0.23, 0.57, P < 0.001). As this is an observational study evaluating an intervention not randomly assigned, there might be some unmeasured residual confounding. Although it is possible that a small number of patients was not registered into the program because they were deemed not eligible, the majority of patients fulfilled the requirements and were not registered because of different reasons. Since the information on the CCT was collected at the end of the study, we do not know the exact timing for when each patient was registered for the program.

CONCLUSIONS

The CCT appears to be a valuable health policy intervention to improve TB treatment outcomes. Incorporating these interventions as established policies may have a considerable effect on the control of TB in similar high-burden areas.

What Do Patients and Experts Want in a Smartphone-Based Application to Support Tuberculosis Treatment Completion?

A mobile application to support individuals receiving treatment for active tuberculosis (TB) by self-administration is being developed with TB experts and patients in active TB treatment using agile development methods to meet the needs of endusers.

From microvasculature to fibroblasts: Contribution of anti-endothelial cell antibodies in systemic sclerosis

Systemic sclerosis (SSc) is an autoimmune disease characterized by skin and internal organ fibrosis, caused by microvascular dysfunction. In recent years, the hypothesis that anti-endothelial cell antibodies (AECA) play a key role in microvascular damage seems to be increasingly convincing. In fact, AECA can induce antibody-dependent cellular apoptosis and stimulate the microvasculature to release pro-inflammatory and pro-fibrotic cytokines. Human-microvascular-endothelial-cells (MVECs) were stimulated with SSc sera (with and without AECA) and with sera from healthy donors. The conditioned MVEC culture media were then added to fibroblast cultures obtained from control skin (CTR), non-affected skin of SSc patients (NA), and affected skin of the same sclerodermic (SSc) patients, respectively. AECA contributed to the MVEC increased release of endothelin-1 (ET-1) in the culture medium and to MVEC apoptosis. Fibroblast (CTR, NA, and SSc) proliferation was increased after treatment with AECA-positive conditioned media, compared to AECA-negative and control conditioned media. Furthermore, both AECA-positive (in major contribution) and AECA-negative conditioned media were responsible for alpha-smooth-muscle-actin (αSMA) over-expression in all fibroblast cultures, compared to control conditioned media. Fibroblast type I collagen synthesis was upregulated by both SSc conditioned media (with and without AECA). Finally, the synthesis of fibroblast transforming-growth-factor-beta (TGF-β) was statistically higher in AECA-positive conditioned media, compared to AECA-negative and control conditioned media. These findings support the concept that AECA may mediate the crosstalk between endothelial damage and dermal-fibroblast activation in SSc.

Qualitative evaluation of a text messaging intervention to support patients with active tuberculosis: implementation considerations

BACKGROUND

Tuberculosis (TB) remains a major global public health problem and mobile health (mHealth) interventions have been identified as a modality to improve TB outcomes. TextTB, an interactive text-based intervention to promote adherence with TB medication, was pilot-tested in Argentina with results supporting the implementation of trials at a larger scale.

OBJECTIVE

The objective of this research was to understand issues encountered during pilot-testing in order to inform future implementation in a larger-scale trial.

METHODS

A descriptive, observational qualitative design guided by a sociotechnical framework was used. The setting was a clinic within a public pulmonary-specialized hospital in Argentina. Data were collected through workflow observation over 115 days, text messages (n=2286), review of the study log, and stakeholder input. Emerging issues were categorized as organizational, human, technical, or sociotechnical considerations.

RESULTS

Issues related to the intervention included workflow issues (eg, human, training, security), technical challenges (eg, data errors, platform shortcomings), and message delivery issues (eg, unintentional sending of multiple messages, auto-confirmation problems). System/contextual issues included variable mobile network coverage, electrical and Internet outages, and medication shortages.

CONCLUSIONS

Intervention challenges were largely manageable during pilot-testing, but need to be addressed systematically before proceeding with a larger-scale trial. Potential solutions are outlined. Findings may help others considering implementing an mHealth intervention to anticipate and mitigate certain challenges. Although some of the issues may be context dependent, other issues such as electrical/Internet outages and limited resources are not unique issues to our setting. Release of new software versions did not result in solutions for certain issues, as specific features used were removed. Therefore, other software options will need to be considered before expanding into a larger-scale endeavor. Improved automation of some features will be necessary, however, a goal will be to retain the intervention capability to be interactive, user friendly, and patient focused. Continued collaboration with stakeholders will be required to conduct further research and to understand how such an mHealth intervention can be effectively integrated into larger health systems.

[Trends of tuberculosis in the Fifth Health Region, Buenos Aires Province, years 2000-2011]

The aim of this study was to describe the trends in tuberculosis (TB) in the Fifth Health Region (RSV) in the Buenos Aires Province. A trend study allowed the evaluation of the average variation of change in the incidence rate (IR) using simple linear regression expressed as a mean annual variation (VAP). The number of reported TB cases and IR per 100 000 population of all TB cases, pulmonary TB (PTB) and bacteriologically confirmed PTB from January 1, 2000 to December 31, 2011, were analyzed by age groups: 0-14; 15-29 and over 64 years of age. The decline in IR was less than 5% for all forms of TB and lower for bacteriologically confirmed PTB cases. The highest rate of PTB and IR was concentrated in the age group of 15-29 years with stable or slightly increasing trend of IR in bacteriologically confirmed PTB. There were similar trends for bacteriologically confirmed PTB in children. The fastest decline in PTB IR occurred in 0-14 age group, while for cases over 64 years of age the decline was sustained over time. TB continues to be a health risk in RSV, with cases in younger age groups. Therefore, it remains necessary to strengthen TB control activities in this region.

MHEALTH INTERVENTION DEVELOPMENT TO SUPPORT PATIENTS WITH ACTIVE TUBERCULOSIS

BACKGROUND

Mobile Health (mHealth) based interventions have been increasingly used to improve a broad range of health outcomes. However, few researchers have reported on the process or the application of theory to guide the development of mHealth based interventions, or specifically for tuberculosis (TB) treatment management.

AIMS

To describe the steps, process, and considerations in developing a text messaging-based intervention to promote treatment adherence and provide support to patients with active TB.

METHODS

Traditional qualitative techniques, including semi-structured interviews, field notes, content analysis, iterative coding, and thematic analysis, were used to design and document the intervention development with a multidisciplinary team of researchers, clinicians, administrators, and patients who were in active TB treatment. The Information-Motivation-Behavioral Skills (IMB) model was used to guide the coding scheme for content analysis of patient-directed TB educational material and intervention development.

RESULTS

The development steps included: a) establishing intervention components, including justifications, considerations, timing and frequency of components; b) developing educational messages, including cultural adaption, text or short message service (SMS) formatting, and prioritizing message delivery order; and c) determining implementation protocol. A set of 16 IMB-based messages were developed for the educational component. Final intervention development was achieved in 3 months.

CONCLUSION

A collaborative approach and application of a theory to guide the intervention design and development is supported. Although a collaborative approach was more time consuming, it resulted in a more responsive, culturally appropriate, and comprehensive intervention. Considerations for developing a text messaging based intervention are provided and may serve as a guide for similar interventions. Further empirical evidence is needed for applying the IMB model for adherence-promotion in TB efforts.

Intracellular accumulation of cell cycle regulatory proteins and nucleolin re-localization are associated with pre-lethal ultrastructural lesions in circulating T lymphocytes: the HIV-induced cell cycle dysregulation revisited

The HIV-induced demise of CD4-T cells is thought to be a result of the execution of genetically programmed cell death that occurs in lymphoid tissue, where many resident T cells are chronically hyperactivated. Since HIV-induced alterations of cell cycle control has been often indicated as prominent mechanism of immune hyper activation and cause of apoptotic death, the signal pathway involved in cell cycle dysregulation of T lymphocytes from HIV infected patients was extensively studied. Here, we also demonstrate that circulating T lymphocytes leave lymphoid tissues with diffused regressive lesions (vacuolization, blebbing, nuclear evanescence and organelle swelling). Equally diffused are biochemical anomalies that accompany the overall disarrangement of cell structure, particularly the fragmentation and diffusion into the cytoplasm of C23/nucleolin, the intracellular accumulation of short lived regulatory proteins and the decrease in expression of membrane proteins. All this is something more than a cell cycle-related remodelling of cell morphology and biochemical mechanisms, and rather recalls a necrotic/oncotic cell damage. Since these changes are associated with adaptive mechanisms to hypoxia, we give evidence for alteration of cell cycle control developing in conditions of scarce energy supply.

Seroprevalence study on the diffusion of the West Nile virus among blood donors, healthcare workers, jockeys, grooms and fowlers, veterinary surgeons and hunters in Messina (Italy)

INTRODUCTION

West Nile virus (WNV) is a mosquito-transmitted flavivirus widely distributed in Africa, Middle East, Asia, Southern Europe and in 1999 was first identified in the United States as a cause of disease in New York City. It mainly circulates among birds, but can infect many species of mammals. Epidemics can occur in rural as well as urban areas.

METHODS

1,280 sera were collected during 2006 from 80 stable workers, as jockey and grooms, 100 fowlers, 500 blood donors, 600 healthcare workers, 100 veterinary surgeons and 100 hunters in the Messina province to evaluate the prevalence of the WNV infection, by ELISA test, in relation to risk exposure or not.

RESULTS

None of the 1280 subjects examined has shown positive for antibodies anti WN virus.

CONCLUSION

Among the strategies of control and surveillance, finally, in our opinion, are and will be indispensable the programs of continuous antibody survey in all the risk categories and in the general population in order to succeed to preview which effects could have the presence of infections from WNV, also imported from other zones where the virus is constantly present, in future and which it could be the impact of geographic factors on the epidemic spread of the disease.

Tuberculosis transmission of predominant genotypes of Mycobacterium tuberculosis in northern suburbs of Buenos Aires city region

In 2003, the incidence of tuberculosis in Argentina showed an increase compared to 2002. The severe national crisis at the end of the 90s has probably strongly contributed to this situation. The goal of this work was to estimate the extent of the spread of the most predominant Mycobacterium tuberculosis strains and to assess the spread of predominant M. tuberculosis clusters as determined by spoligotyping and IS6110 RFLP. The study involved 590 pulmonary, smear-positive TB cases receiving medical attention at health centers and hospitals in Northern Buenos Aires (NBA) suburbs, from October 2001 to December 2002. From a total of 208 clinical isolates belonging to 6 major clusters, 63 (30.2%) isolates had identical spoligotyping and IS6110 RFLP pattern. Only 22.2% were shown to have epidemiological connections with another member of their respective cluster. In these major clusters, 30.2% of the 208 TB cases studied by both molecular techniques and contact tracing could be convincingly attributable to a recently acquired infection. This knowledge may be useful to assess the clonal distribution of predominant M. tuberculosis clusters in Argentina, which may make an impact on TB control strategies.

[Anti- tuberculosis treatment evaluation in northern districts of Buenos Aires suburbs]

The aim of this study was to analyze the epidemiologic impact produced by Direct Observed Treatment Strategy (DOTS) application regarding to its success in the 51h Sanitary Region during the year 2 003. The cure was evaluated by a cohort study comparing two groups. Group 1: Districts in which DOTS were applied in 65% or more TB patients; group 2: Districts applying DOTS in 64% or less, or without its implementation. The global mortality was analyzed on HIV (-) as well as on HIV (+) patients in both groups. In Municipalities where DOTS strategy was applied in >65% of notified cases, the treatment success was 85.7%; the cure rate of bacteriological confirmed pulmonary disease was 86.2% and non-adherence was proved in 8.8% of cases. When DOTS was applied in equal or less than 64% of the cases, the global cure reached 67.6%; in confirmed pulmonary disease it was 68.1%, and non-adherence was proved in 21.8% of cases. Global mortality due to TB was 5.2%; 22.3% in HIV (+) and 4.1% in HIV (-). While In group 1, the cure rate of co-infected TB/HIV patients was 55.2%, non-adherence was 6.9%, in group 2 these figures were 46.4% and 19.7% respectively. Mortality rate in HIV (+) patients was 31.0% in group 1, and 16.1% in group 2. These results show that DOTS application proved to be an efficient tool to cure most of the patients, reaching the proposed goal of 85%, therefore reducing the risk of illness in the community.

Homocysteine induces DNA damage and alterations in proliferative capacity of T-lymphocytes: a model for immunosenescence?

Homocysteine (Hcy) appears to exert different effects on immune functions possibly contributing to age-related pathological states, including vascular diseases, immune dysfunction, and Alzheimer's disease. However, molecular mechanisms underlying Hcy toxicity need to be better characterized. Since T cells are a suitable model to address the possible role of replicative senescence during the in vivo aging, we investigated the effects of high Hcy concentrations on mitogen-activated lymphocytes, with regard to evaluation of DNA damage and cell cycle alterations. Cultured human peripheral blood lymphocytes were stimulated with mitogenic concanavalin A (5 microg/ml) for 48 h in the presence or absence of Hcy (1 mM). Both flow cytometric analysis and caspase-3 activity assay showed an increased rate of apoptosis in Hcy-treated lymphocyte cultures compared to controls. Further, Hcy exposure caused DNA fragmentation as evaluated by single cell gel electrophoresis showing the occurrence of comets. Cytokinesis-block micronucleus assay, performed after addition of cytochalasin B (5 microg/ml) and incubation up to 72 h, revealed a significantly higher frequency of micronucleated/binucleated cells in Hcy-treated cultures compared to controls (P < 0.001). Hcy also reduced cyclin B expression in comparison to control cultures, while cyclin D levels were not significantly affected. Cell cycle alterations, such as the inability of cells to enter into mitosis, could be related with DNA damage. These findings provided a link between perturbation of lymphocyte proliferation homeostasis and commitment towards apoptosis. Our results suggest the involvement of Hcy in the altered immune function associated with age and disease pathology.

Prevalence of SENV-H and SENV-D virus: epidemiological study in blood donors and dialysis patients

INTRODUCTION

Recently, the identification of the SEN virus as a possible etiological agent of parental transmission hepatitis led to the study of the prevalence of such pathogen agents, particularly SENV-H, in our population. This paper compares the rate prevalence in high-risk subjects, such as dialysis patients, and low-risk subjects, such as blood donors.

MATERIAL AND METHODS

The study was carried out on SEN virus DNA extracted from serum of dialysis patients and blood donors, and the presence of viral genomes was performed by the nested PCR method.

RESULTS

The results showed a higher prevalence in male blood donors, supporting the hypothesis of an epidemiological role for sexual and also parental transmission, as is clearly demonstrated by the high prevalence in dialysis patients. The result reduced the importance of the possible etiological role of the SEN virus due to the high percentage of positivity in healthy population, and it induces one to consider poorly significant the pathogenicity of such viral agents.

CONCLUSION

For this instance, the authors, in agreement with the phylogenically related TT virus, described SEN viruses as absolutely not pathogens and considered them as "simple guests."

Aeromonas hydrophila exotoxin induces cytoplasmic vacuolation and cell death in VERO cells

Many organisms are able to cause cell vacuolation, but it is unclear if this can be considered a step of apoptosis or necrosis, or a distinct form of cell death. In this study VERO cells were used to evaluate the relationship between vacuolation and cell death pattern caused by exotoxins produced by environmental strains of A. hydrophila. Cell damage has been evaluated morphologically as well as biochemically. Cytotoxic and vacuolating titres were strictly correlated and the vacuolation has to be considered an early indicator of cytotoxicity that causes cell apoptosis or necrosis in relation to the dose. Signs of apoptosis (chromatin condensation and blebbing) were observed at low concentration and TGase activity, referable to apoptosis induction, confirms morphological observations. In fact, putrescine incorporation was related both to cytotoxin concentration and time of incubation. Moreover, the observed doubling cells with necrotic features permit us to suppose that cell sensitivity and death pattern could change during the different phases of cellular cycle.

First description of Mycobacterium tuberculosis Beijing genotype in Argentina

During a population-based study to genotype isolates of Mycobacterium tuberculosis from Buenos Aires Northern suburbs, we found isolates with molecular patterns related to those of the Beijing genotype. Five out of 590 (0.85%) patients had isolates with spoligopattern identical to that of the Beijing family. Since two of these isolates showed identical IS6110RFLP pattern, we found only four different patterns containing 11 to 19 bands. The isolates were obtained from young people (including a 7 years-old child) who were born in Argentina, and were living in a small area of our region. However, conventional contact tracing did not prove epidemiological linkage among them. These isolates were fully drug-susceptible to the first-line drugs. The comparison of the IS6110RFLP patterns from our isolates against a set of 19 reference Beijing patterns from the RIVM (The Netherlands) confirmed that the strains belonged to the Beijing lineage. These findings might be partially explained by the important migration phenomena occurred during the last decade. Further surveillance studies would help in the following of Beijing family strain dissemination in our community.

[Effects of "host factor" bile on adaptability and virulence of Vibrios, foodborne potential pathogenic agents]

In order to improve the knowledge of host/pathogenic agent interaction and to obtain a more careful estimation of risk related to ingestion of food contaminated by Vibrio spp., the effects of bile extracts have been studied. The growth of one V. fluvialis, two V. alginolyticus, and three V. parahaemolyticus strains, isolated from mollusks and crustaceans, has been determined to evaluate their adaptability to intestinal environment. Moreover, the expression of virulence factors responsible for the colonization, as bacterial "swarming mobility", biofilm production, adherence on epithelial cells and hydrophobicity, has been evaluated. Using a bile concentration of 1.5%, all examined strains showed a constant inhibitory effect, quite moderate in the first growth phases. Bile increased the "swarming mobility" and biofilm production; also the adherence was favored, but only after adaptation and during the early logarithmic phase. The decreased hydrophobicity could explain the reduction of adherence during the stationary phase. Studying the phenotypic expression of virulence factors in "minor vibrios" in the presence of bile, it was possible to extend the knowledge about their pathogenetic mechanisms owing to the ingestion of contaminated food. That permits a more careful estimation of risk related to the contamination, considering the high frequency of isolation of these species in some seafood.

A microplate indicator-based method for determining the susceptibility of multidrug-resistant Mycobacterium tuberculosis to antimicrobial agents

SETTING

Reference Laboratory, Buenos Aires Province Tuberculosis Control Program, Dr Cetrangolo Hospital, Argentina.

OBJECTIVE

To obtain a rapid, inexpensive method of determining minimal inhibitory concentrations (MIC) of several drugs acting on multidrug-resistant Mycobacterium tuberculosis (MDR-TB), a colorimetric, microplate-based assay (M-MTT) was developed.

DESIGN

One hundred and one clinical isolates were studied. Drugs were placed in a microtiter plate, and several two fold dilutions were made in situ. Kanamycin, capreomycin, ethionamide, para-aminosalicylic acid and clarithromycin were tested in a range concentration of 8.0-0.25 microg/ml, cycloserine 60.0-1.9 microg/ml, clofazimine 3.0-0.10 microg/ml, levofloxacin 4.0-0.13 microg/ml and rifabutin 1.0-0.13 microg/ml. General indicator 3-(4,5-dimethylthiazol-2-yl)2,5-diphenyltetrazolium bromide (MTT) at 5.0 mg/ml was used for visualising cellular growth and viability. The proportion method with Middlebrook 7H11 was used as the gold standard.

RESULTS

MICs by M-MTT were obtained at on average 8 days and correlated with those obtained using the proportion method. In our conditions, the total cost of MIC determination for nine drugs was 5.00 US dollars.

CONCLUSION

M-MTT could be used as a simple, rapid, low-cost technology to test the susceptibility of MDR-TB strains to several second-line and alternative drugs, with the objective of orienting future treatment regimens.

[Tuberculosis in the V Sanitary Zone of Buenos Aires Province. Analysis of its trends between 1984 and 1996]

Tuberculosis (TB) continues to be a serious health problem in most of the districts in the 5th Sanitary Region of Buenos Aires Province (RSV) which is located in North Buenos Aires City suburbs. The aim of this study was to analyse and compare the evolution of the TB epidemiological situation in ten districts, in a thirteen year period (1984-96) and to analyse possible reasons for differences. The average annual variation (VAP) of morbidity rate was calculated in order to estimate the trends of TB in these communities along time. Reporting to the National and Provincial TB Control Programmes of TB cases is mandatory for physicians and these data were used as a source of information for the number of cases and rates. A statistical analysis was performed. Our results showed that the VAP value for the whole RSV was lower than -5.0%. On this basis several districts were identified as having a TB critical situation. The proportion of smear positive cases among TB patients reported decreased during this period, suggesting that smear microscopy was being poorly used as a diagnostic tool for TB. Furthermore, the cure rates of the patients attained--in average--only 60.0% and several warning indicators (IA)--like TB meningitis cases and mortality due to TB in people younger than thirty years old, as well as TB--HIV/AIDS association--have been observed to grow in several districts. Previous world global experience and those obtained in other provinces in our own country, suggest that the unique possible strategy for modifying this situation, is to set up the directly observed treatment (DOTS), according to World Health Organization/International Union Against Tuberculosis and Lung Diseases (WHO IVATLD) recommendations, in order to achieve the control of TB.

Transvaginal ultrasound diagnosis of twin reversed arterial perfusion syndrome at 9 weeks' gestation

Diagnosis of twin reversed arterial perfusion syndrome was made using transvaginal sonography at 9 weeks' gestation. The morphological evaluation of the abnormal twin revealed a dysmorphic cephalic pole and absence of the upper extremities. There was diffuse subcutaneous edema and no detectable cardiac activity. The other twin had a normal appearance and a size compatible with the gestational age. The fetuses were divided by a thin amniotic membrane with normal amniotic fluid in both sacs. Diagnosis was confirmed by demonstrating fetal growth and lower limb activity in the abnormal twin 10 days later.