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P Alcabes

Publications and source records attributed to P Alcabes.

At least 19 recordsLinked to original sources
PubMed2003

Prevalence of agr specificity groups among Staphylococcus aureus strains colonizing children and their guardians.

PCR-based assays were used to evaluate agr locus nucleotide polymorphism for the identification of agr autoinducer receptor specificity groups within a population of Staphylococcus aureus isolates colonizing children and their guardians. All isolates could be assigned to one of three major agr groups that had similar prevalences, regardless of whether isolates were implicated in transmission of S. aureus within families. Among healthy carriers, agr groups I to III appear to be equally fit, which may reflect selection for the coexistence of S. aureus strains in a population.

Adult↗
PubMed2001

Increased incidence of multidrug-resistant tuberculosis in diabetic patients on the Bellevue Chest Service, 1987 to 1997.

STUDY OBJECTIVES: To investigate the characteristics of tuberculosis infection in diabetic patients at Bellevue Hospital. DESIGN: We conducted a case-control study retrospectively reviewing the records of patients at Bellevue Hospital Center from 1987 to 1997 with a discharge diagnosis of tuberculosis and diabetes mellitus. SETTING: Bellevue Hospital Center is a 1,200-bed, inner-city municipal hospital located in the Lower East Side of New York City. PATIENTS: Fifty-three identified patients had verified tuberculosis infection and diabetes; of these, 50 charts were available for review. One hundred five control cases were selected from nondiabetic patients with a discharge diagnosis of tuberculosis during the same time period. MEASUREMENTS AND RESULTS: Thirty-six percent (18 cases) of the patients with diabetes and tuberculosis had multidrug-resistant tuberculosis (MDR-TB) compared to only 10% (10 cases) in the control group (p < 0.01) Controlling for homelessness, HIV status, and directly observed therapy, the relative risk of MDR-TB was calculated to be 8.6 (confidence interval, 3.1 to 23.6) in the diabetic group compared to the control group. CONCLUSIONS: There was a significant association between diabetes and MDR-TB. Diabetes continues to be a risk factor for tuberculosis and was associated with MDR-TB in our patients.

Adult↗
PubMed2000

Prevalence of methicillin-resistant and methicillin-susceptible Staphylococcus aureus in the community.

Recent reports indicate that community-acquired methicillin-resistant Staphylococcus aureus (MRSA) infections are increasing and may now involve persons without risk factors predisposing for acquisition. To estimate the extent of community MRSA in New York City, the prevalence of S. aureus and MRSA nasal colonization in a well-patient population of 500 children and guardians was determined. The prevalence of S. aureus nasal carriage was 35% for children and 28% for guardians. One person with predisposing risk factors was colonized with an MRSA, which was identified as the predominant clone found in New York City hospitals. A high degree of methicillin-susceptible S. aureus strain diversity was noted, with no apparent selection for specific clonal types. Thus, MRSA colonization is not ubiquitous in persons without predisposing risk outside of the health care environment. Bacterial competition and a lack of strong selection may limit the community spread of MRSA and can account for its sporadic distribution.

Adolescent↗
PubMed2000

The contribution of recently acquired Mycobacterium tuberculosis infection to the New York City tuberculosis epidemic, 1989-1993.

Current theory in the molecular epidemiology of tuberculosis holds that tuberculosis cases harboring Mycobacterium tuberculosis strains with a common deoxyribonucleic acid (DNA) fingerprint are the result of recent M. tuberculosis transmission. Here we propose a mathematical approach independent of DNA fingerprinting to estimating the percentage of recent transmissions responsible for current tuberculosis incidence. The "short-term reproductive number" of tuberculosis is defined as the average number of tuberculosis cases developing within 1 year of infection. Multiplying the short-term reproductive number by the number of tuberculosis cases in each year and dividing by the subsequent year's tuberculosis case burden equals the proportion of tuberculosis cases in the subsequent year that are due to recent transmission. We carried out separate calculations for human immunodeficiency virus (HIV)-negative and HIV-positive tuberculosis cases. We applied the model to pulmonary (infectious) tuberculosis cases diagnosed in New York City during 1989-1993, using tuberculosis and AIDS surveillance data. Model-based estimates of the proportion of tuberculosis due to recent transmission were lower than estimates based on DNA fingerprints. Reconciliation of these divergent estimates may require the re-estimation of model parameters from data collected de novo, additional model development, and further advances in DNA fingerprinting methods.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Cost-effectiveness of directly observed chemoprophylaxis of tuberculosis among drug users at high risk for tuberculosis.

SETTING: A methadone treatment program with on-site medical care in the Bronx, New York. OBJECTIVE: To define whether costs associated with directly observed preventive therapy (DOPT) of tuberculosis are justified by cases and costs of tuberculosis prevented among persons at high risk for active disease. DESIGN: Detailed data were collected on drug users in treatment regarding human immunodeficiency virus (HIV) and tuberculosis infection and disease, and costs of screening, chemoprophylaxis, direct observation and treatment of active disease. The cost-effectiveness of providing DOPT to this population was modeled. RESULTS: We assessed the impact of providing DOPT to 151 eligible persons. Assuming 65% isoniazid effectiveness, and incorporating costs of screening, observed chemoprophylaxis and clinical monitoring, a net savings in tuberculosis-related hospital costs of $285,284 ($563 per person screened) was associated with DOPT ($10,274 per case prevented). Direct observation of chemoprophylaxis proved cost-effective if associated with even a 10% increment in overall isoniazid effectiveness compared with self-administered chemoprophylaxis. DOPT costs per tuberculosis case averted remained below the in-patient costs of a single case of drug-sensitive disease across a range of parameter values. CONCLUSIONS: Providing DOPT is a highly cost-effective intervention for drug users in treatment. Commitment of additional resources required for DOPT should be given priority in this and other populations at high risk for tuberculosis.

Antibiotic Prophylaxis↗
PubMed1997

Long-term perspective on the prevalent-cohort biases in studies of human immunodeficiency virus progression.

Because considerable information about progression of human immunodeficiency virus (HIV) infection has been provided by studies of cohorts of individuals with prevalent HIV infection, this study was designed to investigate bias due to onset confounding (differential time-since-infection distributions) and differential length-biased sampling in epidemiologic analyses of data from such cohorts. Subjects were participants in the Italian Seroconverters Study, a seroincident cohort of more than 1,200 adults seen at ambulatory care clinics in Italy, with observed HIV seroconversion in 1980-1988. Acquired immunodeficiency syndrome (AIDS) diagnoses, based on the 1987 Centers for Disease Control case definition, and mortality were ascertained through Italian national registries through 1994. To estimate bias in prevalent cohorts, a series of pseudoseroprevalent (PSP) cohorts were drawn by sampling, from among the total seroincident cohort, prevalent AIDS-free subjects in each calendar year. The relative AIDS risk associated with a given covariate was calculated in each PSP cohort and compared with the relative AIDS risk for that covariate in the seroincident cohort. Relative risks were estimated by both the ratio of AIDS incidence densities and the relative AIDS hazards from proportional hazards regression. Differential length bias was not evident, as assessed in the following way: Among 338 individuals with seroconversion dates in 1983-1986, the relative risk of AIDS for subjects born before 1951 compared with those born more recently was 1.67 (95% confidence interval (CI) 1.30-2.14). Although differential length-biased sampling was expected to bias this relative risk toward 1.0, the observed relative risk for earlier birth ranged from 1.79 to 2.86 in 1987-1992 PSP cohorts. Onset bias was observed: Among 644 subjects with seroconversion in 1980-1988, the AIDS relative risk for 1980-1985 seroconverters compared with 1986-1988 seroconverters was 1.09 (95% CI 0.76-1.55). Onset bias was seen in 1988-1990 PSP cohorts (relative risks for early seroconversion = 1.47, 1.46, and 1.34, respectively); in 1991-1992, relative risks were close to the expected value of 1.09, and CIs on relative risks from all PSP cohorts after 1989 included 1.0. Confounding attributable to differential length-biased sampling in prevalent cohorts does not necessarily bias estimates of the impact of covariates on rate of progression to AIDS. Bias can arise when a covariate suspected of affecting AIDS risk is closely linked to date of acquisition of HIV infection. However, onset bias appears to wane as subjects' dates of infection become more remote.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Low serum thiol levels predict shorter times-to-death among HIV-infected injecting drug users.

OBJECTIVES: To investigate whether serum thiol levels are altered by HIV disease, and whether low serum thiols predict time to death among HIV-infected injecting drug users (IDU). DESIGN: A cross-sectional study of serum thiol levels among 13 HIV-seronegative IDU, 116 HIV-seropositive IDU, and 17 HIV-seropositive IDU with a history of AIDS, and a cohort study of the 133 HIV-infected IDU who took part in the cross-sectional study. METHODS: Subjects were recruited from a methadone-maintenance treatment program during 1990-1991. Total serum thiols were determined spectrophotometrically at enrolment; low serum thiols were defined as those with an absorbance at 412 nm < or = 0.46. Deaths through 31 December 1993 were determined from the National Death Index (NDI). Twenty-six HIV-seropositive subjects died during follow up; death certificates, which were obtained for 23 subjects, indicated AIDS or HIV infection for 20. Product-limit estimation was used to calculate survival. Multivariate analyses employed Cox proportional-hazards regression. RESULTS: Analysis of cross-sectional data showed that serum thiols did not differ significantly among HIV-free subjects, HIV-infected subjects, and HIV-infected subjects with a history of AIDS. Cohort analysis, adjusted for age, revealed that persons with those with high serum thiols (relative hazard = 2.83; 95% confidence interval (CI), 1.15, 6.97); a significant interaction between low serum thiols and a history of AIDS was associated with a relative hazard of 5.65 (95% CI, 1.22-2.61). CONCLUSIONS: Among HIV-infected persons, low serum thiols, especially in concert with a history of AIDS, predict mortality risk. These findings support the hypothesis that oxidative stress is critical to the pathogenesis of HIV infection.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Geographic diversity in tuberculosis trends and directly observed therapy, New York City, 1991 to 1994.

The New York City tuberculosis (TB) case rate declined from 1991 to 1994 following more than a decade of increases. The present study investigated TB trends in New York City neighborhoods and their association with neighborhood-specific rates of application of directly observed therapy (DOT). Using Poisson regression models, TB trends in each of New York City's 30 health districts were classified as increasing, decreasing, or stable, as indicated respectively by significant positive, negative, or nonsignificant regression coefficient. Case counts increased in four health districts, decreased in 10, and were stable in 16. Decreasing TB was associated with a higher rate of application of DOT. TB cases among foreign-born persons increased in 12 health districts and were stable in 18, whereas cases among persons born in the United States decreased in 19 and were stable in 11 districts. Among the foreign-born, increasing TB was not associated with a lesser rate of application of DOT. These data provide some support for the role of DOT in containing TB, but also suggest that the application of DOT among foreign-born residents is less effective than among United States-born residents. This may be due to a greater proportion of TB cases among the foreign-born being due to reactivation of TB rather than new infection.

Antitubercular Agents↗
PubMed1996

Use of a quantitative cytomegalovirus (CMV) antigenemia test in evaluating HIV+ patients with and without CMV disease.

Cytomegalovirus (CMV) infection remains a life-threatening infection in patients with HIV disease. A rapid, quantitative diagnostic technique is needed to adi in the diagnosis of CMV disease. This study was undertaken to evaluate the CMV antigenemia test in patients with HIV disease who are at risk for CMV disease. The study included 22 patients who underwent ophthalmologic exams or selected diagnostic techniques in whom CMV cultures and CMV antigenemia tests were performed. All of 11 patients with CMV disease had positive CMV antigenemia assays [range, 48-1,000 positive cells/2 x 10(5) peripheral blood leukocytes (PBL)], and 10 were also CMV viremic. There was no clinical evidence of CMV disease in 11 patients, including seven in whom the CMV antigenemia assay was negative and who remained without evidence of CMV disease after a median follow-up of 159 days. Four patients had low antigenemia levels. Of these four, two subsequently developed CMV retinitis. In conclusion, a positive CMV antigenemia result with > or = 48 positive cells/2 x 10(5) PBL correlated with concurrent CMV disease. The CMV antigenemia test appears to be a valuable tool for the rapid diagnosis of CMV disease in HIV-infected individuals.

AIDS-Related Opportunistic Infections↗
PubMed1996

Effect of stavudine on human immunodeficiency virus type 1 virus load as measured by quantitative mononuclear cell culture, plasma RNA, and immune complex-dissociated antigenemia.

The antiviral effect of stavudine (2', 3'-didehydro-3'-deoxythymidine) against human immunodeficiency virus (HIV) type 1 was measured in 15 HIV-infected patients at baseline and at weeks 4, 10, 22, 34, and 52 of therapy. Patients received 0.1, 0.5, 1.0, or 2.0 mg/kg/day of stavudine. At all time points examined during the 52 weeks of therapy, the median virus titers in peripheral blood mononuclear cells were decreased 1-2 logs, and median immune complex-dissociated antigen levels were reduced 37%-67% compared with baseline values. Plasma RNA content measured by polymerase chain reaction was reduced approximately 0.5 log from baseline median values at both time points examined (weeks 10 and 52). These data demonstrate that stavudine has a substantial and durable antiviral effect.

Antigen-Antibody Complex↗
PubMed1995

Injection drug use and human immunodeficiency virus infection.

In this paper we discuss the epidemiology and natural history of human immunodeficiency virus (HIV) infection in users of injection drugs. Use of injection drugs plays a central role in the HIV infection/AIDS epidemic in the United States, Europe, and many parts of the developing world. The significance of this role has been underappreciated until quite recently because of a number of factors. One factor has been systematic, albeit inadvertent, underreporting of cases of HIV disease and AIDS in drug injectors as a consequence of the initially narrow surveillance case definition for AIDS. A measure of this phenomenon has been the disproportionately larger increment of new cases in this population with each successive revision of the Centers for Disease Control and Prevention's surveillance case definition for AIDS. Other reasons for the underappreciation of the magnitude and consequences of HIV infection and AIDS in injection drug users include the lack of necessary diagnostic facilities in the institutions where drug users are often treated, high mortality rates among HIV-infected drug users for whom a diagnosis of AIDS has not yet been made, the severe marginalization of this population and its lack of advocates, and the localization of the initial epidemic in this population to certain geographic areas.

HIV Infections↗
PubMed1994

Childhood tuberculosis in the Bronx, New York.

The resurgence of tuberculosis (TB) in New York City in the period 1978-92 has been closely linked to the AIDS epidemic but the increase of active TB in areas of urban poverty also implies increased community exposure. We have examined the ecological relation between community rates of AIDS and residential crowding and cases of active TB in Bronx children under age 5. Residential crowding was defined as the percent of households with more than 1 person per room. All childhood TB cases reported between 1986 and 1992 for the Bronx (n = 75) were included. Cumulative AIDS mortality rates for adult females through 1990 represented community HIV burden. All data were coded by the 64 health areas of the borough. We examined trends in these data and used Poisson regression to model the effect of HIV burden and residential crowding on TB risk. For the Bronx as a whole the two variables of TB and residential crowding showed a clear temporal correspondence for the period 1970-90. Residential crowding was associated with poverty and greater dependence on public assistance, large household size, Hispanic ethnicity, and a higher proportion of young children. The overall TB case rate increased with the proportion of crowded households, with a rise from 1.47 to over 8 cases per 10,000 children as the proportion of crowded households increased. At both the lowest and highest levels of AIDS mortality in these areas, the childhood TB risk increased as crowding increased. Children living in areas of the Bronx in which over 12 percent of homes are severely overcrowded were 5.6-fold more likely to develop active TB, even after holding constant the presumed HIV burden in each local community. While HIV infection, the newest risk factor for TB, appears to play a critical role in the resurgent epidemic, our findings show that the earliest known TB risk factors, poverty and household crowding, are still potent forces.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Maturity of human immunodeficiency virus infection and incubation period of acquired immunodeficiency syndrome in injecting drug users.

This study was aimed at estimating the maturity of the human immunodeficiency virus (HIV) epidemic in cohorts of injecting drug users with existing HIV infection at the time of first observation, and using this information to estimate the incubation period of acquired immunodeficiency syndrome (AIDS) in this population group. The method imputed the "missing" time from seroconversion to first observation for seroprevalent subjects in a combined cohort including injecting drug users from New York (n = 246) and Baltimore (n = 621). Imputation relied on a probability model predicting time since seroconversion on the basis of two markers of maturity of HIV infection: percent of CD4+ lymphocytes and platelet count. The model was developed from data observed in a combined cohort of subjects from New York (n = 24) and Baltimore (n = 112) who had incident HIV infections. The estimates of median time since seroconversion for the Baltimore and Bronx seroprevalent subcohorts were 28 and 39 months, respectively. The total time from seroconversion to AIDS was then estimated for the incident plus completed-prevalent cohorts using a modified version of the nonparametric product-limit method. The results showed that approximately 95% (95% confidence interval: 90 to 98%) of drug users remained AIDS-free 2 years after seroconversion; 83% (74-91%), 4 years after seroconversion; and 72% (61-82%), 6 years after seroconversion. Median time to AIDS was 10.2 years, with an estimated 95% confidence interval of 7.9 to 12.3 years. Consistency of these results with those derived from large cohorts of homosexual men indicate that the HIV incubation distributions for drug users and homosexual men are similar.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Laboratory markers and the risk of developing HIV-1 disease among injecting drug users.

OBJECTIVE: To characterize the progression to HIV-1 disease among injecting drug users (IDU) according to laboratory markers. DESIGN: Prospective study of cohort of HIV-1-seroprevalent IDU, with case-comparison component. METHODS: Different laboratory markers were examined as predictors of progression to HIV-1-associated diseases including AIDS in a cohort of 318 HIV-1-infected IDU. The cohort was enrolled from a methadone treatment program in the Bronx, New York, USA. The independent utility of non-CD4 cell markers was evaluated after adjustment for the association of low CD4 lymphocyte count with AIDS risk. Clinical events in the natural history of HIV-1 were related to changes in levels of two variables related to duration of infection, CD4 lymphocyte count and serum beta 2-microglobulin (beta 2M) concentration. RESULTS: On univariate analysis, AIDS incidence measured from baseline increased with declining CD4 lymphocyte number and percentage, increasing serum beta 2M level, low platelet count, low leukocyte count and p24 antigenemia. Among HIV-1-related outcomes prior to any AIDS diagnosis, the relative risk of pyogenic bacterial infections conferred by these markers was similar to the relative risk of AIDS. For all HIV-1 outcomes, the elevated risk encountered at CD4 lymphocyte number < or = 200 x 10(6)/l was entirely due to the high risk at < or = 150 x 10(6)/l. On multivariate analysis, control for CD4 lymphocyte count eliminated the association of any other marker with increased AIDS hazard. HIV-1-related outcomes tended to occur in this order: multiple constitutional symptoms, oral candidiasis, pyogenic bacterial infections and AIDS. CONCLUSIONS: In HIV-1-infected IDU, several laboratory markers may predict AIDS when analyzed individually. These are not, however, independently related to increased AIDS risk after adjustment for low CD4 lymphocyte count. A CD4 count < or = 150 x 10(6)/l is more strongly related to immediate risk of adverse outcome than a count of 200 x 10(6)/l. A progressive series of clinical events is associated with markers of duration of HIV-1 infection, prior to and including AIDS diagnosis.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Correlates of the rate of decline of CD4+ lymphocytes among injection drug users infected with the human immunodeficiency virus.

Changes in the level of CD4-bearing T-lymphocytes in injection drug users infected with the human immunodeficiency virus were evaluated in a sample of 318 subjects enrolled from a methadone program in the Bronx, New York, from 1985 through 1989. Follow-up continued through 1990. The percentage of CD4+ T-lymphocytes (CD4%) was used to maximize the stability of measurements. The rate of decline of the CD4% was determined using a random-effects assumption, and predictors of rate of decline were evaluated using an autoregressive model. The rate of CD4% decline was approximately 1.2 CD4% lost per 6 months, with a higher rate in recent seroconverters (2.2 CD4% lost). The most important predictors of decline of the CD4% in autoregressive models were current pyogenic bacterial infection (CD4% reduced by 2.75, 95% confidence interval (CI) 0.42-5.08), current report of a second constitutional symptom (CD4% reduced by 2.16, 95% CI 0.03-4.29), and history of bacterial infection (CD4% reduced by 1.49, 95% CI 0.09-2.89; proportion of prior CD4% lost increased by 0.14, 95% CI 0.01-0.27). Oral thrush was not related to an accelerated rate of CD4% decline.

Acquired Immunodeficiency Syndrome↗