Incidence and determinants of Pseudomonas aeruginosa infection among persons with HIV: association with hospital exposure.

BACKGROUND: Little information exists on risk factors for Pseudomonas aeruginosa infection in persons with HIV. We assessed the incidence and factors associated with P aeruginosa among persons with HIV enrolled in a large observational cohort study in Los Angeles. METHODS: Data were analyzed from 4825 persons aged > or =13 years with HIV infection enrolled from 4 outpatient facilities from 1990 to 1998. The association between P aeruginosa infection and demographic, risk behavior, and clinical factors was assessed. RESULTS: P aeruginosa was diagnosed in 72 (1.5%) patients representing a crude incidence rate of 0.74 per 100 person-years. The most frequent site of infection was pulmonary (47%). In multivariate analysis, prior hospitalization (adjusted rate ratio = 7.9, 95% CI, 3.8-16.2), and both dapsone (adjusted rate ratio = 4.0, 95% CI, 2.2-7.4) and trimethoprim-sulfamethoxazole (adjusted rate ratio = 2.5, 95% CI, 1.2-5.3) use were independently associated with higher rates of infection. Increasing days of inpatient stay (P <.01) and decreasing CD4(+) counts (P <.01) were strongly associated with P aeruginosa. Azithromycin use decreased the risk of infection by nearly 70%. CONCLUSION: Although the overall observed incidence of P aeruginosa was low, hospital exposure, declining CD4(+) levels, and the use of dapsone or trimethoprim-sulfamethoxazole increased the risk of P aeruginosa disease, and azithromycin use was protective in this population. These findings may assist in the early recognition and diagnosis of persons likely to be at increased risk of P aeruginosa infection.

Seasonality and factors associated with cryptosporidiosis among individuals with HIV infection.

The seasonality and factors associated with Cryptosporidium infection were assessed in a cohort of HIV-infected patients in Los Angeles County to better define the epidemiology of cryptosporidiosis among individuals with HIV. Data were analysed from a cohort of 4247 patients > or = 13 years of age with HIV infection enrolled from four outpatient facilities in Los Angeles, 1990-6. Cryptosporidiosis was diagnosed in 120 (2.8%) patients. Among the 1296 individuals with complete follow-up until death, cryptosporidiosis occurred in 69 (5.3%). The seasonal rate of cryptosporidiosis showed a modest bimodal trend with the highest rates occurring in March-May and September-October. There was no difference in the rate of cryptosporidiosis for the periods of heaviest rainfall (December-March) and low rainfall (April-November). Infection rates were higher among males (1.59 per 100 person-years) than females (0.92) and lower in blacks (0.98) than other racial/ethnic groups (1.80). A significant trend of decreasing cryptosporidiosis was observed with increasing age, with the highest rate (2.34) in the 13-34 year age group. A strong association between cryptosporidiosis and CD4+ count was noted. These data suggest that cryptosporidiosis among HIV-infected individuals in Los Angeles County exhibits a modest spring and fall seasonality. This pattern of occurrence of cryptosporidiosis appears temporally unrelated to local rainfall patterns. Our findings suggest that HIV-infected men, individuals in younger age groups and those with CD4+ lymphocyte counts < 100 x 10(6)/l are at increased risk of cryptosporidiosis. Blacks with HIV infection appear less likely than other racial/ethnic groups to be diagnosed with Cryptosporidium infection. These results may provide insight into possible routes of transmission and sources of cryptosporidiosis infection in individuals with HIV.

Incidence and factors associated with extrapulmonary cryptococcosis among persons with HIV infection in Los Angeles County.

OBJECTIVE: To determine the incidence and factors associated with extrapulmonary cryptococcosis among a cohort of persons with HIV in Los Angeles County. DESIGN: Records-based cohort study. METHODS: Data were analysed from a cohort of 3836 persons aged > or = 13 years with HIV infection enrolled from four outpatient facilities in Los Angeles from 1990 to 1995. The potential association between cryptococcosis and demographic risk behavior and clinical factors was assessed. Possible seasonal clustering was evaluated and an estimate of survival following cryptococcosis was calculated. Multivariate analysis was performed using a Cox proportional hazards approach. RESULTS: Cryptococcosis was identified in 112 patients (2.9%) representing a crude incidence rate of 1.7 cases per 100 person-years experience. The rate of cryptococcosis was higher among men than women (1.9 and 0.6, respectively; P < 0.01) and in Hispanics than in whites (2.3 and 1.2, respectively, P < 0.01). A significant trend of decreasing cryptococcosis was observed with increasing age (P < 0.01). Cryptococcosis increased with declining CD4+ lymphocyte count, with risk being greatest at CD4+ cell counts below 100 x 10(6)/l (P < 0.001). In bivariate analysis persons with a history of antifungal medication had a marginally lower rate of cryptococcosis, but this difference was not statistically significant. The rate of cryptococcosis was significantly higher in fall and winter months [rate ratio (RR), 1.45; 95% confidence interval (CI), 1.0-2.3; P = 0.05]. After controlling for other variables, cryptococcosis was more common in men than women (adjusted RR, 3.2; 95% CI, 1.0-10.4) and in Hispanics than whites (adjusted RR, 1.6; 95% CI, 0.9-2.7). Both CD4+ count and age continued to be strongly associated with the occurrence of cryptococcosis. After controlling for other factors a substantial protective effect was observed for antifungal therapy (adjusted RR, 0.48; 95% CI, 0.29-0.79). CONCLUSION: Our data suggest that HIV-infected men, Hispanics, persons aged under 45 years and those with CD4+ counts under 100 x 10(6)/l have an increased risk of extrapulmonary cryptococcosis. A fall-winter seasonality in the occurrence of cryptococcosis may exist. Significant primary protection against cryptococcal disease is afforded by antifungal therapy. These results may provide insight into possible routes of transmission and sources of cryptococcal infection and help guide both primary prophylaxis and early recognition and diagnosis in persons likely to be at increased risk.

Emerging patterns of HIV transmission: the value of alternative surveillance methods.

OBJECTIVE: To assess the current patterns of HIV transmission in Los Angeles County and determine if AIDS surveillance data accurately reflect these patterns. DESIGN: Records-based cohort study. METHODS: The demographic and HIV risk characteristics of persons considered to be recently infected with HIV (CD4+ count > 700 x 10(6)/l) were determined and compared with the characteristics of persons meeting the Centers for Disease Control and Prevention (CDC) 1993 AIDS case definition. Data were obtained for patients with HIV infection enrolled from four HIV outpatient clinics and analyzed between August 1991 and July 1993. RESULTS: The patient cohort included 1857 persons with HIV infection; 1096 (59.1%) met the CDC 1993 AIDS case definition and 134 (7.2%) had a CD4+ lymphocyte count > 700 x 10(6)/l. The median CD4+ count for the group presumed to be recently infected was 809 x 10(6)/l. Persons considered recently infected with HIV were more likely than those meeting the AIDS case definition to be female (26.1 and 14.5%, respectively; P < 0.001), black (28.4 and 18.2%, respectively; P = 0.001), or male homosexual injecting drug users (IDU; 6.7 and 3.4%, respectively; P = 0.05). After controlling for confounding variables by logistic regression, persons recently infected were more likely to be female [adjusted odds ratio (OR), 3.4; 95% confidence interval (CI), 1.8-6.5; P < 0.001], black (adjusted OR, 1.6; 95% CI, 1.1-2.5; P = 0.02) or male homosexual IDU (adjusted OR, 2.4; 95% CI, 1.1-5.2; P = 0.02) than persons with AIDS. CONCLUSIONS: Our results suggest that the HIV epidemic in Los Angeles County is currently advancing into different subpopulations and indicate that the current patterns of HIV transmission in the County are not fully reflected in standard AIDS surveillance activities. However, our data must be interpreted cautiously because of potential selection and misclassification biases. These findings illustrate the benefits of alternative surveillance mechanisms in detecting important changes in HIV transmission and defining groups at risk, especially in jurisdictions without HIV reporting.