Archive for August 17, 2008

Predicting Antimicrobial Resistance in Invasive Pneumococcal Infections

Clinical Infectious Diseases  1 May 2005  V.40  N.9  p.1288–1297

Otto G. Vanderkooi,1,2 Donald E. Low,1,2 Karen Green,2 Jeff E. Powis,1,2 and Allison McGeer,1,2 for the Toronto Invasive Bacterial Disease Networka

1Department of Laboratory Medicine and Pathobiology, University of Toronto, 2Shared Department of Microbiology, Toronto Medical Laboratories and Mount Sinai Hospital, Toronto, Canada

Background.  The prevalence of multiantimicrobial resistance among Streptococcus pneumoniae continues to increase worldwide. In patients presenting with infection possibly due to pneumococci, recognition of risk factors that would identify those likely to have an antibiotic-resistant isolate might assist clinicians in choosing the most appropriate empirical therapy.

Methods.  A prospective cohort study of invasive pneumococcal infection was conducted in Toronto, Canada. Risk factors for antimicrobial resistance were evaluated by means of univariate and multivariate modeling.

Results.  A total of 3339 patients with invasive pneumococcal infection were identified between 1995 and 2002. Multivariate modeling revealed that risk factors for infection with penicillin-resistant as opposed to penicillin-susceptible pneumococci were year of infection (odds ratio [OR], 1.28; P< .001), absence of chronic organ system disease (OR, 1.72; P=.03), and previous use of penicillin (OR, 2.47; P=.006), trimethoprim-sulfamethoxazole (TMP-SMX; OR, 5.97; P<.001), and azithromycin (OR, 2.78; P=.05). Infection with TMP-SMX–resistant pneumococci was associated with absence of chronic organ system disease (OR, 1.64; P=.001) and with previous use of penicillin (OR, 1.71; P=.03), TMP-SMX (OR, 4.73; P<.001), and azithromycin (OR, 3.49; P=.001). Infection with macrolide-resistant isolates was associated with previous use of penicillin (OR, 1.77; P=.03), TMP-SMX (OR, 2.07; P=.04), clarithromycin (OR, 3.93; P<.001), and azithromycin (OR, 9.93; P<.001). Infection with fluoroquinolone-resistant pneumococci was associated with previous use of fluoroquinolones (OR, 12.1; P<.001), current residence in a nursing home (OR, 12.9; P<.001), and nosocomial acquisition of pneumococcal infection (OR, 9.94; P=.003).

Conclusions.  Knowledge of antimicrobial use during the 3 months before infection is crucial for determining appropriate therapy for a patient presenting to the hospital with an illness for which S. pneumoniae is a possible cause. Nosocomial acquisition and nursing home acquisition are significant risk factors for infection with fluoroquinolone-resistant pneumococci.



August 17, 2008 at 8:24 pm Leave a comment

Asthma as a Risk Factor for Invasive Pneumococcal Disease

N Engl J of Medicine  May 19, 2005  V.352  N.20  p.2082-2090

Thomas R. Talbot, M.D., M.P.H., Tina V. Hartert, M.D., M.P.H., Ed Mitchel, M.S., Natasha B. Halasa, M.D., M.P.H., Patrick G. Arbogast, Ph.D., Katherine A. Poehling, M.D., M.P.H., William Schaffner, M.D., Allen S. Craig, M.D., and Marie R. Griffin, M.D., M.P.H.


Background The risk of invasive pneumococcal disease among persons with asthma is unknown.

Methods We conducted a nested case–control study to examine the association between asthma and invasive pneumococcal disease. The study population included persons 2 to 49 years of age who were enrolled in Tennessee’s Medicaid program (TennCare) for more than one year during the study period (1995 through 2002) and who resided in counties participating in a prospective laboratory-based program of surveillance for invasive pneumococcal disease. For each subject with invasive pneumococcal disease, 10 age-matched controls without invasive pneumococcal disease were randomly selected from the same population. TennCare files were queried to identify the presence of coexisting conditions that confer a high risk of pneumococcal disease. For the purpose of our study, asthma was defined by documentation of one or more inpatient or emergency-department diagnoses of asthma, two outpatient diagnoses, or the use of asthma-related medications. High-risk asthma was defined as asthma requiring admission to a hospital or a visit to an emergency department, the use of rescue therapy or long-term use of oral corticosteroids, or the dispensing of three or more prescriptions for -agonists within the year before enrollment in the study.

Results A total of 635 persons with invasive pneumococcal disease and 6350 controls were identified, of whom 114 (18.0 percent) and 516 (8.1 percent), respectively, had asthma. Persons with asthma had an increased risk of invasive pneumococcal disease (adjusted odds ratio, 2.4; 95 percent confidence interval, 1.9 to 3.1) as compared with controls. Among those without coexisting conditions, the annual incidence of invasive pneumococcal disease was 4.2 episodes per 10,000 persons with high-risk asthma and 2.3 episodes per 10,000 persons with low-risk asthma, as compared with 1.2 episodes per 10,000 persons without asthma.

Conclusions Asthma is an independent risk factor for invasive pneumococcal disease. The risk among persons with asthma was at least double that among controls.


August 17, 2008 at 8:00 pm Leave a comment

Effect of Introduction of the Pneumococcal Conjugate Vaccine on Drug-Resistant Streptococcus pneumoniae

N Engl J of Medicine  April 6, 2006  V.354  N.14  p.1455-1463

Moe H. Kyaw, Ph.D., M.P.H., Ruth Lynfield, M.D., William Schaffner, M.D., Allen S. Craig, M.D., James Hadler, M.D., M.P.H., Arthur Reingold, M.D., Ann R. Thomas, M.D., M.P.H., Lee H. Harrison, M.D., Nancy M. Bennett, M.D., Monica M. Farley, M.D., Richard R. Facklam, Ph.D., James H. Jorgensen, Ph.D., John Besser, M.S., Elizabeth R. Zell, M.Stat., Anne Schuchat, M.D., Cynthia G. Whitney, M.D., M.P.H., for Active Bacterial Core Surveillance of the Emerging Infections Program Network


Background Five of seven serotypes in the pneumococcal conjugate vaccine, introduced for infants in the United States in 2000, are responsible for most penicillin-resistant infections. We examined the effect of this vaccine on invasive disease caused by resistant strains.

Methods We used laboratory-based data from Active Bacterial Core surveillance to measure disease caused by antibiotic-nonsusceptible pneumococci from 1996 through 2004. Cases of invasive disease, defined as disease caused by pneumococci isolated from a normally sterile site, were identified in eight surveillance areas. Isolates underwent serotyping and susceptibility testing.

Results Rates of invasive disease caused by penicillin-nonsusceptible strains and strains not susceptible to multiple antibiotics peaked in 1999 and decreased by 2004, from 6.3 to 2.7 cases per 100,000 (a decline of 57 percent; 95 percent confidence interval, 55 to 58 percent) and from 4.1 to 1.7 cases per 100,000 (a decline of 59 percent; 95 percent confidence interval, 58 to 60 percent), respectively. Among children under two years of age, disease caused by penicillin-nonsusceptible strains decreased from 70.3 to 13.1 cases per 100,000 (a decline of 81 percent; 95 percent confidence interval, 80 to 82 percent). Among persons 65 years of age or older, disease caused by penicillin-nonsusceptible strains decreased from 16.4 to 8.4 cases per 100,000 (a decline of 49 percent). Rates of resistant disease caused by vaccine serotypes fell 87 percent. An increase was seen in disease caused by serotype 19A, a serotype not included in the vaccine (from 2.0 to 8.3 per 100,000 among children under two years of age).

Conclusions The rate of antibiotic-resistant invasive pneumococcal infections decreased in young children and older persons after the introduction of the conjugate vaccine. There was an increase in infections caused by serotypes not included in the vaccine.



August 17, 2008 at 7:57 pm Leave a comment


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