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Volume 15, Number 10—October 2009

Volume 15, Number 10—October 2009   PDF Version [PDF - 7.03 MB - 171 pages]

Research

  • A Model-based Assessment of Oseltamivir Prophylaxis Strategies to Prevent Influenza in Nursing Homes PDF Version [PDF - 672 KB - 9 pages]
    C. van den Dool et al.
        View Abstract

    Prophylaxis with neuraminidase inhibitors is important for controlling seasonal influenza outbreaks in long-term care settings. We used a stochastic individual-based model that simulates influenza virus transmission in a long-term care nursing home department to study the protection offered to patients by different strategies of prophylaxis with oseltamivir and determined the effect of emerging resistance. Without resistance, postexposure and continuous prophylaxis reduced the patient infection attack rate from 0.19 to 0.13 (relative risk [RR] 0.67) and 0.05 (RR 0.23), respectively. Postexposure prophylaxis prevented more infections per dose (118 and 323 daily doses needed to prevent 1 infection, respectively) and required fewer doses per season than continuous prophylaxis. If resistance to oseltamivir was increased, both prophylaxis strategies became less efficacious and efficient, but postexposure prophylaxis posed a lower selection pressure for resistant virus strains. Extension of prophylaxis to healthcare workers offered little additional protection to patients.

  • Nontuberculous Mycobacteria Infections and Anti–Tumor Necrosis Factor-α Therapy PDF Version [PDF - 425 KB - 6 pages]
    K. L. Winthrop et al.
        View Abstract

    Patients receiving anti–tumor necrosis factor-α (anti–TNF-α) therapy are at increased risk for tuberculosis and other granulomatous diseases, but little is known about illness caused by nontuberculous mycobacteria (NTM) in this setting. We reviewed the US Food and Drug Administration MedWatch database for reports of NTM disease in patients receiving anti–TNF-α therapy. Of 239 reports collected, 105 (44%) met NTM disease criteria. Median age was 62 years; the majority of patients (66, 65%) were female, and most (73, 70%) had rheumatoid arthritis. NTM infections were associated with infliximab (n = 73), etanercept (n = 25), and adalimumab (n = 7); most patients were taking prednisone (n = 68, 65%) or methotrexate (n = 58, 55%) concurrently. Mycobacteria avium (n = 52, 50%) was most commonly implicated, and 9 patients (9%) had died at the time their infections were reported. A high rate of extrapulmonary manifestations (n = 46, 44%) was also reported.

  • Nontuberculous Mycobacteria–associated Lung Disease in Hospitalized Persons, United States, 1998–2005 PDF Version [PDF - 690 KB - 8 pages]
    M. E. Billinger et al.
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    The prevalence and trends of pulmonary nontuberculous mycobacteria (NTM)–associated hospitalizations in the United States were estimated using national hospital discharge data. Records were extracted for all persons with a pulmonary NTM International Classification of Diseases code (031.0) hospitalized in the 11 states with continuous data available from 1998 through 2005. Prevalence was calculated using US census data. Pulmonary NTM hospitalizations (031.0) increased significantly with age among both sexes: relative prevalence for persons 70–79 years of age compared with those 40–49 years of age was 15/100,000 for women (9.4 vs. 0.6) and 9/100,000 for men (7.6 vs. 0.83). Annual prevalence increased significantly among men and women in Florida (3.2%/year and 6.5%/year, respectively) and among women in New York (4.6%/year) with no significant changes in California. The prevalence of pulmonary NTM–associated hospitalizations is increasing in selected geographic areas of the United States.

  • Mycobacterium tuberculosis Genotype and Case Notification Rates, Rural Vietnam, 2003–2006 PDF Version [PDF - 742 KB - 8 pages]
    T. N. Buu et al.
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    Tuberculosis case notification rates (CNRs) for young adults in Vietnam are increasing. To determine whether this finding could reflect emergence of Mycobacterium tuberculosis Beijing genotype, we studied all new sputum smear–positive pulmonary tuberculosis patients registered for treatment in 3 rural districts in Vietnam during 2003–2006. Beijing strain infections were more frequent in younger patients (15–24 years of age, 53%) than in older patients (31%; p<0.001). The increase in CNRs for youngest patients was larger for disease caused by the Beijing genotype than by other genotypes, but the difference was not significant. For patients 15–24 years of age, 85% of fluctuations in CNRs between years was caused by fluctuations in Beijing genotype infections compared with 53% and 23% in the groups 25–64 and >65 years of age, respectively (p<0.001). These findings suggest that young adults may be responsible for introducing Beijing strains into rural Vietnam.

  • Lack of Airborne Transmission during Outbreak of Pandemic (H1N1) 2009 among Tour Group Members, China, June 2009 PDF Version [PDF - 471 KB - 3 pages]
    K. Han et al.
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    During June 2–8, 2009, an outbreak of influenza A pandemic (H1N1) 2009 occurred among 31 members of a tour group in China. To identify the mode of transmission and risk factors, we conducted a retrospective cohort investigation. The index case-patient was a female tourist from the United States. Secondary cases developed in 9 (30%) tour group members who had talked with the index case-patient and in 1 airline passenger (not a tour group member) who had sat within 2 rows of her. None of the 14 tour group members who had not talked with the index case-patient became ill. This outbreak was apparently caused by droplet transmission during coughing or talking. That airborne transmission was not a factor is supported by lack of secondary cases among fellow bus and air travelers. Our findings highlight the need to prevent transmission by droplets and fomites during a pandemic.

  • Medscape CME Activity
    Community-Associated Methicillin-Resistant Staphylococcus aureus, Iowa, USA PDF Version [PDF - 660 KB - 8 pages]
    P. Van De Griend et al.
    View Summary

    The proportion of invasive methicillin-resistant Staphylococcus aureus infections caused by USA300 increased in 2006.

        View Abstract

    We performed antimicrobial drug susceptibility testing and molecular typing on invasive methicillin-resistant Staphylococcus aureus (MRSA) isolates (n = 1,666) submitted to the University of Iowa Hygienic Laboratory during 1999–2006 as part of a statewide surveillance system. All USA300 and USA400 isolates were resistant to <3 non–β-lactam antimicrobial drug classes. The proportion of MRSA isolates from invasive infections that were either USA300 or USA400 increased significantly from 1999–2005 through 2006 (p<0.0001). During 2006, the incidence of invasive community-associated (CA)–MRSA infections was highest in the summer (p = 0.0004). Age <69 years was associated with an increased risk for invasive CA-MRSA infection (odds ratio [OR] 5.1, 95% confidence interval [CI] 2.06–12.64), and hospital exposure was associated with decreased risk (OR 0.07, 95% CI 0.01–0.51).

  • Healthcare Worker Occupation and Immune Response to Pneumocystis jirovecii PDF Version [PDF - 516 KB - 8 pages]
    R. Tipirneni et al.
        View Abstract

    The reservoir and mode of transmission of Pneumocystis jirovecii remain uncertain. We conducted a cross-sectional study of 126 San Francisco General Hospital staff in clinical (n = 103) and nonclinical (n = 23) occupations to assess whether occupational exposure was associated with immune responses to P. jirovecii. We examined antibody levels by ELISA for 3 overlapping fragments that span the P. jirovecii major surface glycoprotein (Msg): MsgA, MsgB, and MsgC1. Clinical occupation participants had higher geometric mean antibody levels to MsgC1 than did nonclinical occupation participants (21.1 vs. 8.2, p = 0.004); clinical occupation was an independent predictor of higher MsgC1 antibody levels (parameter estimate = 0.89, 95% confidence interval 0.29–1.48, p = 0.003). In contrast, occupation was not significantly associated with antibody responses to either MsgA or MsgB. Healthcare workers may have occupational exposure to P. jirovecii. Humans may be a reservoir for P. jirovecii and may transmit it from person to person.

  • Nosocomial Outbreak of Novel Arenavirus Infection, Southern Africa PDF Version [PDF - 607 KB - 5 pages]
    J. T. Paweska et al.
        View Abstract

    A nosocomial outbreak of disease involving 5 patients, 4 of whom died, occurred in South Africa during September–October 2008. The first patient had been transferred from Zambia to South Africa for medical management. Three cases involved secondary spread of infection from the first patient, and 1 was a tertiary infection. A novel arenavirus was identified. The source of the first patient’s infection remains undetermined.

  • Review of an Influenza Surveillance System, Beijing, People’s Republic of China PDF Version [PDF - 548 KB - 7 pages]
    P. Yang et al.
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    In 2007, a surveillance system for influenza-like illness (ILI) and virologic data was established in Beijing, China. The system tracked ILI and laboratory-confirmed influenza in 153 general hospitals from September 1, 2007, through April 30, 2008. To analyze the ILI surveillance data (weekly ILI rates and counts) and the effectiveness of the system, we used the US Centers for Disease Control and Prevention Early Aberration Reporting System. The data indicated that the highest rate of influenza isolation and the highest ILI count occurred in the first week of 2008. The system enabled us to detect the onset and peak of an epidemic.

  • Discriminatory Ability of Hypervariable Variable Number Tandem Repeat Loci in Population-based Analysis of Mycobacterium tuberculosis Strains, London, UK PDF Version [PDF - 537 KB - 8 pages]
    P. Velji et al.
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    To address conflicting results about the stability of variable number tandem repeat (VNTR) loci and their value in prospective molecular epidemiology of Mycobacterium tuberculosis, we conducted a large prospective population-based analysis of all M. tuberculosis strains in a metropolitan setting. Optimal and reproducible conditions for reliable PCR and fragment analysis, comprising enzymes, denaturing conditions, and capillary temperature, were identified for a panel of hypervariable loci, including 3232, 2163a, 1982, and 4052. A total of 2,261 individual M. tuberculosis isolates and 265 sets of serial isolates were analyzed by using a standardized 15-loci VNTR panel, then an optimized hypervariable loci panel. The discriminative ability of loci varied substantially; locus VNTR 3232 varied the most, with 19 allelic variants and Hunter-Gaston index value of 0.909 unNN. Hypervariable loci should be included in standardized panels because they can provide consistent comparable results at multiple settings, provided the proposed conditions are adhered to.

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