17 resultados para antiretroviral
Resumo:
An important factor in determining a patient's adherence to antiretroviral therapy is the patient's commitment to follow the regimen. This suggests that therapy should be initiated when the patient is willing to commit to the regimen. Starting when the patient is ready may be more important than the laboratory values suggested by various guidelines. In order to increase understanding of patient readiness for antiretroviral therapy HIV infected patients were surveyed to determine the factors that influenced their decision to initiate antiretroviral therapy and to continue to adhere to therapy once started. A sample of 83 HIV infected patients who were currently on antiretroviral regimens completed a 25-item investigator-developed questionnaire. The questionnaire sought information on the length of time from learning of HIV positive status and readiness to initiate therapy. The questionnaire also addressed demographic, psychological and social factors thought to be associated with readiness for adhering to therapy. (Abstract shortened by UMI.)^
Resumo:
The scale-up of antiretrovirals (ARVs) to treat HIV/AIDS in Africa has been rapid over the last five years. Botswana was the first African nation to roll out a comprehensive ARV program, where ARVs are available to all citizens who qualify. Excellent adherence to these ARVs is necessary to maintain HIV suppression and on-going health of all individuals taking them. Children rely almost entirely on their caregivers for the administration of these medications, and very little research has been done to examine the factors which affect both adherence and disclosure to the child of their HIV status. ^ Methods. This cross-sectional study used multiple methods to examine adherence, disclosure, and stigma across various dimensions of the child and caregiver's lives, including 30 caregiver questionnaires, interviewer-administered 3-day adherence recalls, pharmacy pill counts, and chart reviews. Fifty in-depth interviews were conducted with caregivers, male caregivers, teenagers, and health care providers. ^ Results. Perceived family stigma was found to be a predictor of excellent adherence. After controlling for age, children who live with their mothers were significantly less likely to know their HIV status than children living with any other relative (OR=0.403, p=0.014). Children who have a grandmother living in the household or taking care of them each day are significantly more likely to have optimal adherence than children who don't have grandmother involvement in their daily lives. ^ Discussion. Visible illness plays an intermediary role between adherence and perceived family stigma: Caregivers know that ARVs suppress physical manifestations of HIV, and in an effort to avoid unnecessary disclosure of the child's status to family members, therefore have children with excellent adherence. Grandmothers play a vital role in supporting the care and treatment of children in Botswana. ^
Resumo:
Highly active antiretroviral therapy (HAART) has taken HIV-infection from a rapidly terminal illness to one that is a slowly progressive, chronic illness. HIV-infected children can now live long, normal lives. Today, four classes of antiretroviral medications are widely used and several antiretrovirals are available in each class, but resistance and cross-resistance to these medications can occur very quickly if the patient does not adhere to strict medication dosing guidelines. One method to improve pediatric adherence to antiretrovirals is to focus on identified determinants of adherence at clinical visits, but very few studies have been conducted to identify determinants of adherence to antiretrovirals and the best methods to measure adherence in the pediatric population. This research synthesis found adherence factors related to children can be divided into child-identified factors and caregiver-identified factors. Child identified factors include medication-related, demographic-related, cognitive-related, psychosocial-related, and biological marker-related barriers to adherence. Caregiver identified factors include medication-related, cognitive-related, relationship-related, and psychosocial-related barriers to adherence. More randomized clinical trials are needed to identify determinants to adherence, identify methods to best measure adherence, and to identify the best interventions to improve adherence in HIV-infected children and adolescents. ^
Resumo:
Context: Despite tremendous strides in HIV treatment over the past decade, resistance remains a major problem. A growing number of patients develop resistance and require new therapies to suppress viral replication. ^ Objective: To assess the safety of multiple administrations of the anti-CD4 receptor (anti-CD4) monoclonal antibody ibalizumab given as intravenous (IV) infusions, in three dosage regimens, in subjects infected with human immunodeficiency virus (HIV-1). ^ Design: Phase 1, multi-center, open-label, randomized clinical trial comparing the safety, pharmacokinetics and antiviral activity of three dosages of ibalizumab. ^ Setting: Six clinical trial sites in the United States. ^ Participants: A total of twenty-two HIV-positive patients on no anti-retroviral therapy or a stable failing regimen. ^ Intervention: Randomized to one of two treatment groups in Arms A and B followed by non-randomized enrollment in Arm C. Patients randomized to Arm A received 10 mg/kg of ibalizumab every 7 days, for a total of 10 doses; patients randomized to Arm B received a total of six doses of ibalizumab; a single loading dose of 10 mg/kg on Day 1 followed by five maintenance doses of 6 mg/kg every 14 days, starting at Week 1. Patients assigned to Arm C received 25 mg/kg of ibalizumab every 14 days for a total of 5 doses. All patients were followed for safety for an additional 7 to 8 weeks. ^ Main Outcome Measures: Clinical and laboratory assessments of safety and tolerability of multiple administrations of ibalizumab in HIV-infected patients. Secondary measures of efficacy include HIV-1 RNA (viral load) measurements. ^ Results: 21 patients were treatment-experienced and 1 was naïve to HIV therapy. Six patients were failing despite therapy and 15 were on no current HIV treatment. Mean baseline viral load (4.78 log 10; range 3.7-5.9) and CD4+ cell counts (332/μL; range 89-494) were similar across cohorts. Mean peak decreases in viral load from baseline of 0.99 log10(1.11 log10, and 0.96 log 10 occurred by Wk 2 in Cohorts A, B and C, respectively. Viral loads decreased by >1.0 log10 in 64%; 4 patients viral loads were suppressed to < 400 copies/mL. Viral loads returned towards baseline by Week 9 with reduced susceptibility to ibalizumab. CD4+ cell counts rose transiently and returned toward baseline. Maximum median elevations above BL in CD4+ cell counts for Cohorts A, B and C were +257, +198 and +103 cells/μL, respectively and occurred within 3 Wks in 16 of 22 subjects. The half-life of ibalizumab was 3-3.5 days and elimination was characteristic of capacity-limited kinetics. Administration of ibalizumab was well tolerated. Four serious adverse events were reported during the study. None of these events were related to study drug. Headache, nausea and cough were the most frequently reported treatment emergent adverse events and there were no laboratory abnormalities related to study drug. ^ Conclusions: Ibalizumab administered either weekly or bi-weekly was safe, well tolerated, and demonstrated antiviral activity. Further studies with ibalizumab in combination with standard antiretroviral treatments are warranted.^
Resumo:
Safer sex practices, such as consistent condom use, are essential to reduce HIV transmission. Determining causes and/or co-variants related to the likelihood of participating in high-risk sexual behaviors may allow the content of interventions and treatments to minimize HIV transmission to be tailored more effectively. The goal of this study was to examine whether a relationship exists between consistent condom use among African American HIV-positive crack cocaine users and both (1) the use of antiretroviral therapy, and (2) adherence to antiretroviral therapy regimens. The study population consisted of 390 participants. They were at least 18 years old, African American, HIV-positive, and had used crack cocaine within a month prior to an interview conducted sometime between April, 2004, and September, 2007. Bivariate associations were examined using contingency tables and χ2-statistics. The Mantel-Haenszel method was used to control for confounding. This study found neither a significant relationship between use of antiretroviral therapy and consistent condom use (Odds ratio (OR) = 1.38; 95% Confidence interval (95%CI) = 0.86–2.22), nor an association between antiretroviral therapy adherence and consistent condom use (OR = 1.02, 95%CI = 0.60–1.75). The exception was more consistent condom use when sex was traded for money or drugs in those on antiretroviral therapy, compared to those not on such therapy (OR = 2.28, 95%CI = 1.08–4.85). Further studies examining condom use and HIV treatment adherence are recommended. ^
Resumo:
Mean corpuscular volume, which is an inexpensive and widely available measure to assess, increases in HIV infected individuals receiving zidovudine and stavudine raising the hypothesis that it could be used as a surrogate for adherence.^ The aim of this study was to examine the association between mean corpuscular volume and adherence to antiretroviral therapy among HIV infected children and adolescents aged 0–19 years in Uganda as well as the extent to which changes in mean corpuscular volume predict adherence as determined by virologic suppression.^ The investigator retrospectively reviewed and analyzed secondary data of 158 HIV infected children and adolescents aged 0–19 years who initiated antiretroviral therapy under an observational cohort at the Baylor College of Medicine Children's Foundation - Uganda. Viral suppression was used as the gold standard for monitoring adherence and defined as viral load of < 400 copies/ml at 24 and 48 weeks. ^ Patients were at least 48 weeks on therapy, age 0.2–18.4 years, 54.4% female, 82.3% on zidovudine based regimen, 92% WHO stage III at initiation of therapy, median pre therapy MCV 80.6 fl (70.3–98.3 fl), median CD4% 10.2% (0.3%–28.0%), and mean pre therapy viral load 407,712.9 ± 270,413.9 copies/ml. For both 24 and 48 weeks of antiretroviral therapy, patients with viral suppression had a greater mean percentage change in mean corpuscular volume (15.1% ± 8.4 vs. 11.1% ± 7.8 and 2.3% ± 13.2 vs. -2.7% ± 10.5 respectively). The mean percentage change in mean corpuscular volume was greater in the first 24 weeks of therapy for patients with and without viral suppression (15.1% ± 8.4 vs. 2.3% ± 13.2 and 11.1% ± 7.8 vs. -2.7% ± 10.5 respectively). In the multivariate logistic regression model, percentage change in mean corpuscular volume ≥ 20% was significantly associated with viral suppression (adjusted OR 4.0; CI 1.2–13.3; p value 0.02). The ability of percentage changes in MCV to correctly identify children and adolescents with viral suppression was higher at a cut off of ≥ 20% (90.7%; sensitivity, 31.7%) than at ≥ 9% (82.9%; sensitivity, 78.9%). Negative predictive value was lower at ≥ 20% change (25%; specificity, 84.8%) than at ≥ 9% change (33.3%; specificity, 39.4%).^ Mean corpuscular volume is a useful marker of adherence among children and adolescents with viral suppression. ^
Resumo:
Objective. Predictors of non-adherence to antiretroviral medications in a population of low-income, multiethnic, HIV-positive smokers were investigated. ^ Methods. A secondary analysis was conducted using baseline data collected from 326 patients currently prescribed antiretrovirals enrolled in a randomized clinical trial assessing smoking outcomes. Variables evaluated included demographics, stress, depression, nicotine dependence, illicit drug use and alcohol use. ^ Results. The average age of participants was 45.9 years (SD=7.6). The majority of participants were male (72.1%), Black (76.7%), reported sexual contact as the method of HIV exposure (heterosexual (43%) and MSM (27%)) and were antiretroviral adherent (60.4%). Results from unadjusted analyses indicated depression (OR=1.02; 95% CI=1.00-1.04), illicit drug use (OR=2.39; 95% CI=1.51-3.79) and alcohol consumption (OR=2.86; 95% CI=1.79-4.57) were associated with non-adherence. Multivariate analyses indicated nicotine dependence (OR=1.13; 95% CI=1.02-1.25), illicit drug use (OR=2.10; 95% CI=1.27-3.49) and alcohol use (OR=2.50; 95% CI=1.52-4.12) were associated with nonadherence. ^ Conclusions. Illicit drug use, alcohol use and nicotine dependence are formidable barriers to antiretroviral adherence in this population. Future research is needed to assess how to address these variables in the context of improving antiretroviral adherence for individuals living with HIV/AIDS.^
Resumo:
The aims of the study were to determine the prevalence of and factors that affect non-adherence to first line antiretroviral (ARV) medications among HIV infected children and adolescents in Botswana. The study used secondary data from Botswana-Baylor Children's Clinical Center of Excellence for the period of June 2008 to February 10th, 2010. The study design was cross-sectional and case-comparison between non-adherent and adherent participants was used to examine the effects of socio-demographic and medication factors on non-adherence to ARV medications. A case was defined as non-adherent child with adherence level < 95% based on pill count and measurement of liquid formulations. The comparison group consisted of children with adherence levels ≥95%.^ A total of 842 participants met the eligibility criteria for determination of the prevalence of non-adherence and 338 participants (169 cases and 169 individuals) were used in the analysis to estimate the effects of factors on non-adherence. ^ Univariate and multivariable logistic regression were used to estimate the association between non-adherence (outcome) and socio-demographic and medication factors (exposures). The prevalence of non-adherence for participants on first line ARV medications was 20.0% (169/842).^ Increase in age (OR (95% CI): 1.10 (1.04–1.17) p = 0.001) was associated with nonadherence, while increase in number of caregivers (OR (95% CI): 0.72 (0.56–0.93) p = 0.01) and increase in number of monthly visits (OR (95% CI): 0.92 (0.86–0.99) p = 0.02), were associated with good adherence in both the unadjusted and the adjusted models. For the categorical variables, having more than two caregivers (OR (95% CI): 0.66 (0.28–0.84), p = 0.002) was associated with good adherence even in the adjusted model. ^ Conclusion. The prevalence of non-adherence to antiretroviral medicines among the study population was estimated to be 20.0%. In previous studies, adherence levels of ≥ 95% have been associated with better clinical outcomes and suppression of virus to prevent development of resistance. Older age, fewer numbers of caregivers and fewer monthly visits were associated with non-adherence. Strategies to improve and sustain adherence especially among older children are needed. The role of caregivers and social support should be investigated further.^
Resumo:
Background. Consistent adherence to antiretroviral treatment is necessary for a treatment success. Improving and maintaining adherence rate >95% are challenging for health care professionals. This pilot randomized controlled study aimed to evaluate the impact of the interactive intervention on adherence to GPO-VIR, to describe the feasibility of the interactive intervention in Thailand, and to illustrate the adherence self-efficacy concept among HIV treatment-naïve patients in Thailand who were starting antiretroviral treatment. ^ Methods. The study took place at three HIV clinics located in Phayao, Thailand. Twenty-three patients were randomly assigned into the experimental (n=11) and the control groups (n=12). Each participant in the experimental group and a significant person to the patient received 5 educational sessions with a nurse at the clinics and at their homes. They also received 3 follow-up evaluations during the 6-month period of the study. The participants in the control group received the standard of care provided by HIV clinical personnel plus three follow-up evaluations at the clinic. ^ Results. Seventeen patients (7 in the experimental and 10 in the control group) completed the study. The 4-day recall on the Thai ACTG Adherence Scale demonstrated adherence rate >95% for most participants from both groups. After the first measurement, no experimental group patients reporting missing ART, while one control group participant continuously skipped ART. Participants from both groups had significantly increased CD4 cell counts after the study (F(1, 15) = 29.30, p = .000), but no differences were found between two groups (F(1, 15) = .001, p = .98). Examination of the intervention showed limitations and possibilities to implement it in Thailand. Qualitative data demonstrated self-efficacy expectations, resignation and acceptance as related concepts to improve adherence outcomes. ^ Conclusions. This interactive intervention, after appropriate modifications, is feasible to apply for Thai HIV-treatment naïve patients. Because of limitations the study could not demonstrate whether the interactive intervention improved adherence to ART among HIV-treatment naïve in Thailand. A longitudinal study in a larger sample would be required to test the impact of the intervention. ^ Keyword: antiretroviral treatment, adherence, treatment-naïve, Thailand, randomized controlled study ^
Resumo:
The purpose of this research was two-fold; to investigate the effect of institutionalization on death and CD4 decline in a cohort of 325 HIV-infected Romanian children, and to investigate the effect of disclosure of the child's own HIV status in this cohort. All children were treated with Kaletra-based highly active antiretroviral therapy, and were followed from November, 2001 through October, 2004. The mean age of the children included in the cohort is 13. The study found that children in biological families were more likely to experience disease progression through either death or CD4 decline than children in institutions (p=0.04). The family home-style institution may prove to be a replicable model for the safe and appropriate care of HIV-infected orphaned and abandoned children and teens. The study also found that children who do not know their own HIV infection status were more likely to experience disease progression through either death or CD4 decline than children who know their HIV diagnosis (p=0.03). This evidence suggests that, in the context of highly active anti retroviral therapy, knowledge of one's own HIV infection status is associated with delayed HIV disease progression. ^
Resumo:
The global social and economic burden of HIV/AIDS is great, with over forty million people reported to be living with HIV/AIDS at the end of 2005; two million of these are children from birth to 15 years of age. Antiretroviral therapy has been shown to improve growth and survival of HIV-infected individuals. The purpose of this study is to describe a cohort of HIV-infected pediatric patients and assess the association between clinical factors, with growth and mortality outcomes. ^ This was a historical cohort study. Medical records of infants and children receiving HIV care at Mulago Pediatric Infectious Disease Clinic (PIDC) in Uganda between July 2003 and March 2006 were analyzed. Height and weight measurements were age and sex standardized to Centers for Disease Control and prevention (CDC) 2000 reference. Descriptive and logistic regression analyses were performed to identify covariates associated with risk of stunting or being underweight, and mortality. Longitudinal regression analysis with a mixed model using autoregressive covariance structure was used to compare change in height and weight before and after initiation of highly active antiretroviral therapy (HAART). ^ The study population was comprised of 1059 patients 0-20 years of age, the majority of whom were aged thirteen years and below (74.6%). Mean height-for-age before initiation of HAART was in the 10th percentile, mean weight-for-age was in the 8th percentile, and the mean weight-for-height was in the 23rd percentile. Initiation of HAART resulted in improvement in both the mean standardized weight-for-age Z score and weight-for-age percentiles (p <0.001). Baseline age, and weight-for-age Z score were associated with stunting (p <0.001). A negative weight-for-age Z score was associated with stunting (OR 4.60, CI 3.04-5.49). Risk of death decreased from 84% in the >2-8 years age category to 21% in the >13 years age category respectively, compared to the 0-2 years of age (p <0.05). ^ This pediatric population gained weight significantly more rapidly than height after starting HAART. A low weight-for-age Z score was associated with poor survival in children. These findings suggest that age, weight, and height measurements be monitored closely at Mulago PIDC. ^
Resumo:
Background. Injecting drug users (IDUs) are at risk of infection with Hepatitis C Virus (HCV) and Human Immunodeficiency Virus (HIV). Independently, each of these viruses is a serious threat to health, with HIV ravaging the body’s immune system, and HCV causing cirrhosis, liver cancer and liver failure. Co-infection with HIV/HCV weakens the response to antiretroviral therapy in HIV patients. IDUs with HIV/HCV co-infection are at a 20 times higher risk of having liver-related morbidity and mortality than IDUs with HIV alone. In Vietnam, studies to ascertain the prevalence of HIV have found high rates, but little is known about their HCV status. ^ Purpose. To measure the prevalence of HCV and HIV infection and identify factors associated with these viruses among IDUs at drug treatment centers in northern Vietnam. ^ Methods. A cross-sectional study was conducted from November 2007 to February 2008 with 455 injecting drug users aged 18 to 39 years, admitted no more than two months earlier to one of four treatment centers in Northern Vietnam (Hatay Province) (response rate=95%). Participants, all of whom had completed detoxification and provided informed consent, completed a risk assessment questionnaire and had their blood drawn to test for the presence of antibody-HCV and antibody-HIV with enzyme immuno assays. Univariate and multivariable logistic regression models were utilized to explore the strength of association using HIV, HCV infections and HIV/HCV co-infection as outcomes and demographic characteristics, drug use and sexual behaviors as factors associated with these outcomes. Unadjusted and adjusted odds ratios and 95% confidence intervals were calculated. ^ Results. Among all IDU study participants, the prevalence of HCV alone was 76.9%, HIV alone was 19.8%. The prevalence of HIV/HCV co-infection was 92.2% of HIV-positive and 23.7% of HCV-positive respondents. No sexual risk behaviors for lifetime, six months or 30 days prior to admission were significantly associated with HCV or HIV infection among these IDUs. Only duration of injection drug use was independently associated with HCV and HIV infection, respectively. Longer duration was associated with higher prevalence. Nevertheless, while HCV infection among IDUs who reported being in their first year of injecting drugs were lower than longer time injectors, their rates were still substantial, 67.5%. ^ Compared with either HCV mono-infection or HIV/HCV non-infection, HIV/HCV co-infection was associated with the length of drug injection history but was not associated with sexual behaviors. Higher education was associated with a lower prevalence of HIV/HCV co-infection. When compared with HIV/HCV non-infection, current marriage was associated with a lower prevalence of HIV/HCV co-infection. ^ Conclusions. HCV was prevalent among IDUs from 18 to 39 years old at four drug treatment centers in northern Vietnam. Co-infection with HCV was predominant among HIV-positive IDUs. HCV and HIV co-infection were closely associated with the length of injection drug history. Further research regarding HCV/HIV co-infection should include non-injecting drug users to assess the magnitude of sexual risk behaviors on HIV and HCV infection. (At these treatment centers non-IDUs constituted 10-20% of the population.) High prevalence of HCV prevalence among IDUs, especially among HIV-infected IDUs, suggests that drug treatment centers serving IDUs should include not only HIV prevention education but they should also include the prevention of viral hepatitis. In addition, IDUs who are HIV-positive need to be tested for HCV to receive the best course of therapy and achieve the best response to HIV treatment. These data also suggest that because many IDUs get infected with HCV in the first year of their injection drug career, and because they also engaged in high risk sexual behaviors, outreach programs should focus on harm reduction, safer drug use and sexual practices to prevent infection among drug users who have not yet begun injecting drugs and to prevent further spread of HCV, HIV and co-infection. ^
Resumo:
Mother to child transmission of human immunodeficiency virus (HIV) has decreased dramatically in the United States since the mid-1990s. Without antiretroviral therapy the risk of perinatal infection is as high as 25%; with treatment the risk drops to <1-2%. However, state surveillance data show a recent rise in the percentage of babies being born with HIV in Texas. No studies of perinatal HIV transmission in Texas have focused on the individual cases and identified what social/institutional barriers stood in the way of the index woman, her support system and her health providers in negotiating access to prenatal care and HIV treatment.^ The Texas Department of State Health Services identifies the babies born in Texas with HIV infection. This two year study will use mixed methods to identify barriers to the diagnosis and treatment of maternal HIV. In-depth interviews and chart reviews will be used to conduct the study. The abstracted medical record will give us demographic data and details of the timing of testing and treatment; interviews will provide information as to the individual and environmental factors that may have delayed testing and treatment. Little research has been done to assess the factors contributing to late prenatal HIV diagnosis and care in Texas and the interventions identified by mothers of affected babies that might overcome these obstacles.^ Conclusions from this study will guide the development of interventions to better educate the public, reduce structural barriers common to the underserved, and/or educate health care professionals. The study will also serve as a model for other states to undertake evaluation of their cases of perinatal infection. ^
Resumo:
HIV-1 infected children display a highly variable rate of progression to AIDS. Data about reasons underlying the variable progression to AIDS among vertically-infected children is sparse, and the few studies that have examined this important question have almost exclusively been done in the developed world. This is despite the fact that Sub-Saharan Africa is home to over 90% of all HIV infected children around the world.^ The main objective of this study was to examine predictors of HIV-1 slow progression among vertically infected children in Botswana, using a case control design. Cases (slow progressors) and controls (rapid progressors) were drawn from medical records of HIV-1 infected children being followed up for routine care and treatment at the BBCCCOE between February 2003 and February 2011. Univariate and Multivariate Logistic Regression Analyses were performed to identify independent predictors of slow disease progression and control for confounding respectively. ^ The study population comprised of 152 cases and 201 controls with ages ranging from 6 months to 16 years at baseline. Low baseline HIV-1 RNA viral load was the strongest independent predictor of slow progression (adjusted OR = 5.52, 95% CI = 2.75-11.07; P <0.001). Other independent predictors of slow disease progression identified were: lack of history of PMTCT with single dose Nevirapine plus Zidovudine (adjusted OR = 4.45, 95% CI = 1.45-13.69; P = 0.009) and maternal vital status (alive) (adjusted OR = 2.46, 95% CI = 1.51-4.01; P < 0.00 ).^ The results of this study may help clinicians and policy-makers in resource-limited settings to identify, at baseline, which children are at highest risk of rapid progression to AIDS and thus prioritize them for immediate intervention with HAART and other measures that would mitigate disease progression. At the same time HAART may be delayed among children who are at lower risk of disease progression. This would enable the highly affected, yet impoverished, Sub-Saharan African countries to use their scarce resources more efficiently which may in turn ensure that their National Antiretroviral Therapy Programs become more sustainable. Delaying HAART among the low-risk children would also lower the occurrence of adverse drug reactions associated with antiretroviral drugs exposure.^ Keywords. Slow Progressors, Rapid Progressors, HIV-1, Predictors, Children, Vertical Transmission, Sub-Saharan Africa^
Resumo:
Staphylococcus aureus is a common microorganism in humans, typically colonizing the nasopharynx, skin and other mucosal surfaces. It is among the most frequent causes of clinically-significant bacterial infections accounting for increased morbidity and mortality among individuals with HIV/AIDS. Evidence of higher colonization rates among high-risk HIV populations have been observed however, prevalence estimates have varied. Additionally, behavioral, biological, and/or environmental factors that may account for these high colonization rates are not understood. Previous literature on clinic-based surveys were subject to considerable biases. Additionally, representative samples of high-risk HIV populations were difficult to obtain due in part to an underrepresentation of individuals who may not regularly obtain health care. ^ The main objective of this project is to determine the prevalence of methicillin-sensitive S. aureus (MSSA) and methicillin-resistant (MRSA) nasal colonization in two populations: 1) men who have sex with men (MSM) and 2) injection drug users (IDU). Both of these populations are included in the third round of the National HIV Behavioral Surveillance System (NHBS) in Houston, Texas. ^ In the NHBS-MSM3 study, logistic regression was used to report odds ratios and 95% confidence intervals (CI). For the NHBS-IDU3 study, to account for the lack of independence between samples, the method of generalized estimating equations was utilized to report adjusted odds ratios and 95% CI. The NHBS-MSM3 study enrolled 202 participants with a MSSA colonization rate of 26.7% and MRSA rate of 3%. In the NHBS-IDU3 study, 18.4% were nasally colonized with MSSA and 5.7% were nasally colonized with MRSA. Among the NHBS-MSM3 population, high-risk sexual practices were associated with colonization. For the NHBS-IDU3 population, age, marital status, employment status, and the presence of scabs, were associated with colonization status when controlling for size of recruitment network. In multivariate GEE analyses, the use of antiretroviral medications and age remained significantly associated with S. aureus nasal colonization when controlling for size of recruitment network and gender. In both studies, a significantly higher than expected S. aureus and MRSA colonization rate was observed as compared to colonization rates described for the general population. However, these estimates were moderate in comparison to reported clinic-based MSM and IDU S. aureus colonization findings. This study validates substantial prevalence differences and biases that may exist with data collected from clinic-based MSM and IDU. The prevalence of MSSA and MRSA nasal colonization did not differ significantly with respect to HIV status among NHBS-MSM3/NHBS-IDU3 participants. Continued examination on the effects of S. aureus colonization and infection should be examined longitudinally to confirm additional community-based determinants in populations that are disproportionately affected.^