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Defining the Population-Based Burden of Nosocomial Pneumococcal Bacteremia
Outi Lyytikäinen, MD, PhD;
Peter Klemets, MD;
Petri Ruutu, MD, PhD;
Tarja Kaijalainen, PhD;
Merja Rantala, DVM;
Jukka Ollgren, MSc;
J. Pekka Nuorti, MD, DSc
Arch Intern Med. 2007;167(15):1635-1640.
Background The characteristics, risk factors, and outcome of patients with nosocomial pneumococcal bacteremia (NPB) have not been described in large, population-based studies.
Methods All episodes of invasive pneumococcal infections reported by Finnish clinical microbiology laboratories (positive blood or cerebrospinal fluid culture) from January 1, 1995, through December 31, 2002, were linked to data in national health care registries and vital statistics to obtain information on the patient's preceding hospitalizations, comorbidities, and outcome of illness. Pneumococcal bacteremia was defined as nosocomial if the first positive blood culture was obtained more than 2 days after hospital admission, or if the patient had been hospitalized for more than 2 days within 7 days of the first positive blood culture.
Results Information on hospital admission was available for 4217 of 4357 persons (96.8%) with invasive pneumococcal infections. We identified 387 NPBs (9.7%) among 3973 pneumococcal bacteremias. Patients with NPB were older (median age, 67 years vs 52 years; P < .001) and were more likely to have at least 1 high-risk condition (other than age  65 years), for which 23-valent pneumococcal polysaccharide vaccine is recommended (59.2% vs 34.6%; P < .001), compared with patients who had community-associated pneumococcal bacteremias. The case fatality proportion at 28 days was higher in patients with NPB than in those with community-associated pneumococcal bacteremias (23.8% vs 10.8%; P < .001). Pneumococcal serotypes included in 23-valent polysaccharide vaccine and 7-valent conjugate vaccine caused 71.5% and 46.1% of NPBs, respectively.
Conclusions A substantial proportion of pneumococcal bacteremias are health care associated. The high prevalence of conditions for which pneumococcal polysaccharide vaccine is recommended provides opportunities for strengthening prevention efforts in these patients at high risk of illness and death.
Author Affiliations: Department of Infectious Disease Epidemiology, National Public Health Institute, Helsinki, Finland (Drs Lyytikäinen, Klemets, Ruutu, and Nuorti and Mr Ollgren); Laboratory for Chlamydia and Respiratory Tract Bacteria, National Public Health Institute, Oulu, Finland (Dr Kaijalainen); and Antimicrobial Research Laboratory, National Public Health Institute, Turku, Finland (Dr Rantala). Dr Nuorti is now with the Respiratory Diseases Branch, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia.
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