Antonio G. Pacheco

Multilocus Variable-Number Tandem Repeat Analysis Distinguishes Outbreak and Sporadic Escherichia coli O157:H7 Isolates

ABSTRACT Escherichia coli O157:H7 is a major cause of food-borne illness in the United States. Outbreak detection involves traditional epidemiological methods and routine molecular subtyping by pulsed-field gel electrophoresis (PFGE). PFGE is labor-intensive, and the results are difficult to analyze and not easily transferable between laboratories. Multilocus variable-number tandem repeat (VNTR) analysis (MLVA) is a fast, portable method that analyzes multiple VNTR loci, which are areas of the bacterial genome that evolve quickly. Eighty isolates, including 21 isolates from five epidemiologically well-characterized outbreaks from Pennsylvania and Minnesota, were analyzed by PFGE and MLVA. Strains in PFGE clusters were defined as strains that differed by less than or equal to one band by using XbaI and the confirmatory enzyme SpeI. MLVA was performed by comparing the number of tandem repeats at seven loci. From 6 to 30 alleles were found at the seven loci, resulting in 64 MLVA types among the 80 isolates. MLVA correctly identified the isolates from all five outbreaks if only a single-locus variant was allowed. MLVA differentiated strains with unique PFGE types. Additionally, MLVA discriminated strains within PFGE-defined clusters that were not known to be part of an outbreak. In addition to being a simple and validated method for E. coli O157:H7 outbreak detection, MLVA appears to have a sensitivity equal to that of PFGE and a specificity superior to that of PFGE.

Changing Mortality Profile among HIV-Infected Patients in Rio de Janeiro, Brazil: Shifting from AIDS to Non-AIDS Related Conditions in the HAART Era

Introduction We describe temporal trends in the mortality rates and factors associated with AIDS and non-AIDS related mortality at the Evandro Chagas Clinical Research Institute (IPEC), Oswaldo Cruz Foundation (FIOCRUZ). Methods Adult patients enrolling from 1986 through 2009 with a minimum follow up of 60 days were included. Vital status was exhaustively checked using patients’ medical charts, through active contact with individuals and family members and by linkage with the Rio de Janeiro Mortality database using a previously validated algorithm. The CoDe protocol was used to establish the cause of death. Extended Cox proportional hazards models were used for multivariate modeling. Results A total of 3530 individuals met the inclusion criteria, out of which 868 (24.6%) deceased; median follow up per patient was 3.9 years (interquartile range 1.7–9.2 years). The dramatic decrease in the overall mortality rates was driven by AIDS-related causes that decreased from 9.19 deaths/100PYs n 1986–1991 to 1.35/100PYs in 2007–2009. Non-AIDS related mortality rates remained stable overtime, at around 1 death/100PYs. Immunodeficiency significantly increased the hazard of both AIDS-related and non-AIDS-related causes of death, while HAART use was strongly associated with a lower hazard of death from either cause. Conclusions Our results confirm the remarkable decrease in AIDS-related mortality as the HIV epidemic evolved and alerts to the conditions not traditionally related to HIV/AIDS which are now becoming more frequent, needing careful monitoring.

Effect of improved tuberculosis screening and isoniazid preventive therapy on incidence of tuberculosis and death in patients with HIV in clinics in Rio de Janeiro, Brazil: a stepped wedge, cluster-randomised trial

BACKGROUND Preventive therapy for tuberculosis in patients with HIV is effective, but it has not been widely implemented in moderate or high-burden settings. We assessed the effect of widespread use of isoniazid preventive therapy on rates of tuberculosis and death in people with HIV in Brazil. METHODS We did a stepped wedge, cluster-randomised trial with patients actively enrolled in 29 HIV clinics in Rio de Janeiro. Clinic staff were trained in tuberculosis screening, use of tuberculin skin tests, and use of isoniazid preventive therapy. Clinics were randomly allocated a date to begin the intervention period, with two clinics beginning the intervention every 2 months starting from Sept 1, 2005. The primary outcome was tuberculosis incidence alone or combined with death in the control versus intervention periods until Aug 31, 2009. This trial is registered at ClinicalTrials.gov, number NCT00107887. RESULTS Of 17,413 patients in the cohort, 12,816 were eligible for the intervention. Overall, there were 475 tuberculosis cases and 838 deaths. The intervention increased the rate of patients receiving skin tests from 19 per 100 person-years to 59 per 100 person-years, and from 36 per 100 person-years to 144 per 100 person-years for those eligible for isoniazid preventive therapy. In the control period, 221 cases of tuberculosis were diagnosed (1.31 per 100 person-years) compared with 254 (1.10 per 100 person-years) in the intervention period (unadjusted hazard ratio [HR] 0.87; 95% CI 0.69-1.10). Rates of tuberculosis incidence or death were 3.64 and 3.04 per 100 person-years, respectively (0.76; 95% CI 0.66-0.87). When adjusted for age, sex, entry CD4 count, and use of antiretroviral therapy, the HR for tuberculosis was 0.73 (95% CI 0.54-0.99) and for tuberculosis or death was 0.69 (0.57-0.83). INTERPRETATION Operational training aimed at increasing tuberculosis screening, provision of tuberculin skin tests, and use of isoniazid preventive therapy in Brazilian HIV clinics significantly reduced incident tuberculosis and death. Thus, scale-up of preventive therapy for HIV-infected patients in settings of moderate tuberculosis incidence is achievable and should be widely implemented in Brazil and elsewhere. FUNDING Bill & Melinda Gates Foundation and the National Institutes of Health.

Genetic, epidemiological and biological analysis of interleukin-10 promoter single-nucleotide polymorphisms suggests a definitive role for 819C/T in leprosy susceptibility

Leprosy is a complex infectious disease influenced by genetic and environmental factors. The genetic contributing factors are considered heterogeneous and several genes have been consistently associated with susceptibility like PARK2, tumor necrosis factor (TNF), lymphotoxin-α (LTA) and vitamin-D receptor (VDR). Here, we combined a case–control study (374 patients and 380 controls), with meta-analysis (5 studies; 2702 individuals) and biological study to test the epidemiological and physiological relevance of the interleukin-10 (IL-10) genetic markers in leprosy. We observed that the −819T allele is associated with leprosy susceptibility either in the case–control or in the meta-analysis studies. Haplotypes combining promoter single-nucleotide polymorphisms also implicated a haplotype carrying the −819T allele in leprosy susceptibility (odds ratio (OR)=1.40; P=0.01). Finally, we tested IL-10 production in peripheral blood mononuclear cells stimulated with Mycobacterium leprae antigens and found that −819T carriers produced lower levels of IL-10 when compared with non-carriers. Taken together, these data suggest that low levels of IL-10 during the disease outcome can drive patients to a chronic and unprotective response that culminates with leprosy.

Temporal changes in causes of death among HIV-infected patients in the HAART era in Rio de Janeiro, Brazil

Background:The widespread use of highly active antiretroviral therapy (HAART) has led to marked decreases in death rates in Brazil in HIV-infected individuals. Nonetheless, there are scarce data on specific causes of death. Methods:Death rates from a cohort of HIV-infected patients in Rio de Janeiro, Brazil, were analyzed in 2-year periods, from 1997 to 2006. Poisson models and survival models accounting for competing risks were used to assess association of covariables. A standardized validated algorithm was used to ascertain specific causes of death. Results:Of the 1538 eligible patients, 226 (14.7%) died during the study period, corresponding to a mortality rate of 3.2 per 100 person-years. The median follow-up time was 4.61 years (interquartile range = 5.63 years) and the loss to follow-up rate was 2.4 per 100 person-years. Overall, 98 (43.4%) were classified as non-AIDS-related causes. Although opportunistic infections were the leading causes of death (37.6%), deaths due to AIDS-related causes declined significantly over time (P < 0.01). In the most recent period (2005-2006), the rate of non-AIDS-related causes of deaths was higher than that of AIDS-related causes of death. Conclusions:In the HAART era, there has been a significant change in causes of death among HIV-infected patients in Rio de Janeiro. As access to HAART improves, integration with other public programs will become critically important for the long-term success of HIV/AIDS programs in developing countries.

Metabolic syndrome in HIV-infected individuals: underlying mechanisms and epidemiological aspects

The success of highly active antiretroviral therapy (HAART) has determined a dramatic decline in AIDS- and immunodeficiency-related causes of death in the HIV-infected population. As life-expectancy increases, such individuals have become gradually exposed not only to the effects of aging itself, but also to the influence of environmental risk factors, which are known to act in the general population. These features can lead to obesity, diabetes mellitus and ultimately cardiovascular diseases (CVD). Metabolic complications and abnormal fat distribution were frequently observed after a few years of antiretroviral therapy and, as the array of antiretroviral drugs became broader, long term metabolic alterations are becoming far more common worldwide. Nevertheless, the risk of not being on HAART is overwhelmingly greater than the metabolic adverse events in terms of morbidity and mortality events. HIV/HAART-induced metabolic unbalances overlap in some extent the components of Metabolic Syndrome (MetS) and its high rates in the HIV population place infected individuals in an elevated CVD risk category. MetS can explain at least in part the emergence of CVD as the major morbidity and mortality conditions in the HIV population. In this review we convey information on the underlying aspects of MetS during HIV infection, highlighting some physiopathological and epidemiological features of this comorbidity along with the role played by HIV itself and the synergy action of some antiretroviral drugs. Considerations on MetS management in the HIV population are also depicted.

TNF -308G>A Single Nucleotide Polymorphism Is Associated With Leprosy Among Brazilians: A Genetic Epidemiology Assessment, Meta-Analysis, and Functional Study

Leprosy is an infectious disease caused by Mycobacterium leprae. Tumor necrosis factor (TNF) plays a key role in the host response. Some association studies have implicated the single nucleotide polymorphism TNF -308G>A in leprosy susceptibility, but these results are still controversial. We first conducted 4 association studies (2639 individuals) that showed a protective effect of the -308A allele (odds ratio [OR] = 0.77; P = .005). Next, results of a meta-analysis reinforced this association after inclusion of our new data (OR = 0.74; P = .04). Furthermore, a subgroup analysis including only Brazilian studies suggested that the association is specific to this population (OR = 0.63; P = .005). Finally, functional analyses using whole blood cultures showed that patients carrying the -308A allele produced higher TNF levels after lipopolysaccharide (LPS) (6 hours) and M. leprae (3 hours) stimulation. These results reinforce the association between TNF and leprosy and suggest the -308A allele as a marker of disease resistance, especially among Brazilians.

Toll-like Receptor 1 N248S Single-Nucleotide Polymorphism Is Associated With Leprosy Risk and Regulates Immune Activation During Mycobacterial Infection

Conflicting findings about the association between leprosy and TLR1 variants N248S and I602S have been reported. Here, we performed case-control and family based studies, followed by replication in 2 case-control populations from Brazil, involving 3162 individuals. Results indicated an association between TLR1 248S and leprosy in the case-control study (SS genotype odds ratio [OR], 1.81; P = .004) and the family based study (z = 2.02; P = .05). This association was consistently replicated in other populations (combined OR, 1.51; P < .001), corroborating the finding that 248S is a susceptibility factor for leprosy. Additionally, we demonstrated that peripheral blood mononuclear cells (PBMCs) carrying 248S produce a lower tumor necrosis factor/interleukin-10 ratio when stimulated with Mycobacterium leprae but not with lipopolysaccharide or PAM3cysK4. The same effect was observed after infection of PBMCs with the Moreau strain of bacillus Calmette-Guerin but not after infection with other strains. Finally, molecular dynamics simulations indicated that the Toll-like receptor 1 structure containing 248S amino acid is different from the structure containing 248N. Our results suggest that TLR1 248S is associated with an increased risk for leprosy, consistent with its hypoimmune regulatory function.

Long-term protection from isoniazid preventive therapy for tuberculosis in HIV-infected patients in a medium burden tuberculosis setting: the TB/HIV in Rio (THRio) Study

BACKGROUND The duration of protection against tuberculosis provided by isoniazid preventive therapy is not known for human immunodeficiency virus (HIV)-infected individuals living in settings of medium tuberculosis incidence. METHODS We conducted an individual-level analysis of participants in a cluster-randomized, phased-implementation trial of isoniazid preventive therapy. HIV-infected patients who had positive tuberculin skin tests (TSTs) were followed until tuberculosis diagnosis, death, or administrative censoring. Nelson-Aalen cumulative hazard plots were generated and hazards were compared using the log-rank test. Cox proportional hazards models were fitted to investigate factors associated with tuberculosis diagnosis. RESULTS Between 2003 and 2009, 1954 patients with a positive TST were studied. Among these, 1601 (82%) initiated isoniazid. Overall tuberculosis incidence was 1.39 per 100 person-years (PY); 0.53 per 100 PY in those who initiated isoniazid and 6.52 per 100 PY for those who did not (adjusted hazard ratio [aHR], 0.17; 95% confidence interval [CI], .11-.25). Receiving antiretroviral therapy at time of a positive TST was associated with a reduced risk of tuberculosis (aHR, 0.69; 95% CI, .48-1.00). Nelson-Aalen plots of tuberculosis incidence showed a constant risk, with no acceleration in 7 years of follow-up for those initiating isoniazid preventive therapy. CONCLUSIONS Isoniazid preventive therapy significantly reduced tuberculosis risk among HIV-infected patients with a positive TST. In a medium-prevalence setting, 6 months of isoniazid in HIV-infected patients with positive TST reduces tuberculosis risk over 7 years of follow-up, in contrast to results of studies in higher-burden settings in Africa.

Mortality associated with discordant responses to antiretroviral therapy in resource-constrained settings

Objectives:We assessed mortality associated with immunologic and virologic patterns of response at 6 months of highly active antiretroviral therapy (HAART) in HIV-infected individuals from resource-limited countries in Africa and South America. Methods:Patients who initiated HAART between 1996 and 2007, aged 16 years or older, and had at least 1 measurement (HIV-1 RNA plasma viral load or CD4 cell count) at 6 months of therapy (3-9 month window) were included. Therapy response was categorized as complete, discordant (virologic only or immunologic only), and absent. Associations between 6-month response to therapy and all-cause mortality were assessed by Cox proportional hazards regression. Robust standard errors were calculated to account for intrasite correlation. Results:A total of 7160 patients, corresponding to 15,107 person-years, were analyzed. In multivariable analysis adjusted for age at HAART initiation, baseline clinical stage and CD4 cell count, year of HAART initiation, clinic, occurrence of an AIDS-defining condition within the first 6 months of treatment, and discordant and absent responses were associated with increased risk of death. Conclusions:Similar to reports from high-income countries, discordant immunologic and virologic responses were associated with intermediate risk of death compared with complete and no response in this large cohort of HIV-1 patients from resource-limited countries. Our results support a recommendation for wider availability of plasma viral load testing to monitor antiretroviral therapy in these settings.