Investigation and control of an outbreak of Achromobacter xylosoxidans bacteremia.

OBJECTIVE: To define the extent of an outbreak of Achromobacter xylosoxidans bacteremia, determine the source of the outbreak, and implement control measures. DESIGN: An outbreak investigation, including environmental and infection control assessment, and evaluation of hypotheses using the binomial distribution and case control studies. SETTING: A 50-bed medical surgical unit in a hospital in Illinois during the period January 1-July 15, 2006. INTERVENTIONS: Discontinuation of use of opioid delivery via patient-controlled analgesia (PCA) until the source of the outbreak was identified and implementation of new protocols to ensure more rigorous observation of PCA pump cartridge manipulations. RESULTS: Calculations based on the binomial distribution indicated the probability that all 9 patients with A. xylosoxidans bacteremia were PCA pump users by chance alone was <.001. A subsequent case control study identified PCA pump use for administration of morphine as a risk factor for A. xylosoxidans bacteremia (odds ratio, undefined; P < .001). Having a PCA pump cartridge with morphine started by nurse C was significantly associated with becoming a case-patient (odds ratio, 46; 95% confidence interval, 4.0-525.0; P < .001). CONCLUSIONS: We hypothesize that actions related to diversion of morphine by nurse C were the likely cause of the outbreak. An aggressive pain control program involving the use of opioid medication warrants an equally aggressive policy to prevent diversion of medication by staff.

National outbreak of Acanthamoeba keratitis associated with use of a contact lens solution, United States.

An outbreak of Acanthamoeba keratitis, a rare, potentially blinding, corneal infection, was detected in the United States in 2007; cases had been increasing since 2004. A case-control study was conducted to investigate the outbreak. We interviewed 105 case-patients from 30 states and 184 controls matched geographically and by contact lens use. Available contact lenses, cases, solutions, and corneal specimens from case-patients were cultured and tested by molecular methods. In multivariate analyses, case-patients had significantly greater odds of having used Advanced Medical Optics Complete Moisture Plus (AMOCMP) solution (odds ratio 16.9, 95% confidence interval 4.8-59.5). AMOCMP manufacturing lot information was available for 22 case-patients, but none of the lots were identical. Three unopened bottles of AMOCMP tested negative for Acanthamoeba spp. Our findings suggest that the solution was not intrinsically contaminated and that its anti-Acanthamoeba efficacy was likely insufficient. Premarket standardized testing of contact lens solutions for activity against Acanthamoeba spp. is warranted.

Spectrum of infection and risk factors for human monkeypox, United States, 2003.

For the 2003 monkeypox virus (MPXV) outbreak in the United States, interhuman transmission was not documented and all case-patients were near or handled MPXV-infected prairie dogs. We initiated a case-control study to evaluate risk factors for animal-to-human MPXV transmission. Participants completed a questionnaire requesting exposure, clinical, and demographic information. Serum samples were obtained for analysis of immunoglobulin G (IgG) and IgM to orthopoxvirus. When data were adjusted for smallpox vaccination, case-patients were more likely than controls to have had daily exposure to a sick animal (odds ratio [OR] 4.0, 95% confidence interval [CI] 1.2-13.4), cleaned cages and bedding of a sick animal (OR 5.3, 95% CI 1.4-20.7), or touched a sick animal (OR 4.0, 95% CI 1.2-13.4). These findings demonstrate that human MPXV infection is associated with handling of MPXV-infected animals and suggest that exposure to excretions and secretions of infected animals can result in infection.

Two outbreaks of occupationally acquired histoplasmosis: more than workers at risk.

OBJECTIVE: The objective of this study was to determine the etiology and risk factors for acute histoplasmosis in two outbreaks in Illinois among laborers at a landfill in 2001 and at a bridge reconstruction site in 2003. DESIGN: We performed environmental investigations during both outbreaks and also performed an analytic cohort study among bridge workers. PARTICIPANTS: Workers at the landfill during May 2001 and those at the bridge site during August 2003 participated in the study. At the landfill, workers moved topsoil from an area that previously housed a barn; at the bridge, workers observed bat guano on bridge beams. EVALUATIONS/MEASUREMENTS: We defined a case by positive immunodiffusion serology, a > or = 4-fold titer rise in complement fixation between acute and convalescent sera, or positive urinary Histoplasma capsulatum (HC) antigen. Relative risks (RR) for disease among bridge workers were calculated using bivariate analysis. RESULTS: Eight of 11 landfill workers (73%) and 6 of 12 bridge workers (50%) were laboratory-confirmed histoplasmosis cases. Three bridge workers had positive urinary HC antigen. At the bridge, seeing or having contact with bats [RR = 7.0; 95% confidence interval (CI), 1.1-43.0], jack-hammering (RR = 4.0; 95% CI, 1.2-13.3), and waste disposal (RR = 4.0; 95% CI, 1.2-13.3) were the most significant job-related risk factors for acquiring histoplasmosis. CONCLUSIONS: Workers performing activities that aerosolized topsoil and dust were at increased risk for acquiring histoplasmosis. Relevance to professional and clinical practice: Employees should wear personal protective equipment and use dust-suppression techniques when working in areas potentially contaminated with bird or bat droppings. Urinary HC antigen testing was important in rapidly identifying disease in the 2003 outbreak.

Interruption and discontinuation of highly active antiretroviral therapy in the multicenter AIDS cohort study.

OBJECTIVE: Identify the determinants and consequences of interrupting and discontinuing highly active antiretroviral therapy (HAART) among a population-based cohort of HIV-infected men. METHODS: Longitudinal analyses were applied to 2916 person-visit pairs (589 men) of continuous HAART use, 243 person-visit pairs (154 men) during which HAART was interrupted, and 151 person-visit pairs (130 men) in which HAART was discontinued by the second visit. HIV RNA increase was defined as > or =1 log10 copies/mL across the visit pairs. RESULT: : Younger age, black race, geographic location, higher HIV RNA level, depression, shorter time on HAART, lower medication adherence, and not taking a lamivudine-containing regimen predicted interrupting HAART use. Younger age, higher HIV RNA level, depression, and taking an abacavir- or lopinavir-containing regimen predicted discontinuing HAART. Among men with < or =1000 HIV RNA copies/mL, approximately 5% of those who interrupted HAART for < or =7 days and those who continued HAART had an HIV RNA increase. Men with longer interruptions and HAART discontinuers had significantly higher rates of HIV RNA increases (35.7% and 70.5%, respectively). Discontinuation and long interruptions resulted in lower CD4 cell counts. CONCLUSIONS: Host characteristics play a role in short interruptions, whereas longer interruptions may be clinically indicated. These longer stoppages had further virologic and immunologic consequences, however.