Epidemiologic Notes and Reports Group A Beta-Hemolytic Streptococcal Bacteremia -- Colorado, 1989
From January through August 1989, group A beta-hemolytic Streptococcus (GABHS) was isolated from blood cultures obtained from 19 patients who had been admitted to a hospital in metropolitan Denver, Colorado. In comparison, this organism was cultured from blood from eight patients in 1988 and three in 1987 at this hospital (Figure 1). The Colorado Department of Health was notified of this increase, and in August, the department reviewed these patients' medical charts to describe GABHS bacteremia cases and to determine whether they represented community-acquired disease, nosocomial acquisition, or laboratory artifact.
Patients ranged in age from 3 weeks to 96 years (median: 67 years); 12 were male. All but one were residents of Colorado when hospitalized; 16 patients lived in the Denver metropolitan area. Twelve patients were admitted from private residences and four from nursing homes; three were transferred from acute- or extended-care facilities.
For 13 patients, a blood specimen was obtained within 6 hours of arrival at the hospital; 12 patients had presenting manifestations consistent with bacteremia or sepsis (primarily fever, chills, rigors, and a focus of infection). In only three patients was bacteremia first documented greater than 48 hours after hospitalization.
Seven patients had no identified source of bacteremia; four had a possible cutaneous source of infection (cellulitis, impetigo, open sores, or an abscess); seven had pneumonia, and one had both cutaneous and respiratory infections. Two of the seven without identified sources of infection developed GABHS bacteremia following major trauma in motor vehicle crashes. A third patient developed GABHS bacteremia following elective laser hemorrhoidectomy. Two patients developed acute respiratory distress syndrome; two developed acute renal failure; and nine (47%) died after developing GABHS bacteremia.
Eight group A Streptococcus blood culture isolates from this hospital were sent to CDC for typing. Three were M-type 1, T-type 1; three were M-type 3, T-type 3/13; and two were not typable.
Retrospective surveys of this and 17 other metropolitan Denver hospital microbiology laboratories identified 73 cases of GABHS bacteremia between January and August--a rate of seven cases per 100,000 per year in the general population of the Denver metropolitan area.
Active surveillance for GABHS bacteremia was established in September 1989 in metropolitan Denver. Bacterial isolates are sent to CDC for analysis, and ongoing case investigation is examining potential explanations for the increasing incidence of group A streptococcal disease and possible risk factors, such as age, underlying illnesses, socioeconomic status, and race/ethnicity. Reported by: C Voeck, N Armstrong, F Trail, M Wheeler, M Roe, J Todd, MD, RE Hoffman, MD, State Epidemiologist, Colorado Dept of Health. Div of Field Svcs, Epidemiology Program Office; Respiratory Diseases Br, Div of Bacterial Diseases, Center for Infectious Diseases, CDC.
Editorial Note: During the last half century, the incidence of severe infections with group A Streptococcus (including bacteremia, puerperal sepsis, and scarlet fever) and nonsuppurative sequelae (such as rheumatic fever) has decreased markedly in the United States. Potential explanations for this decline may relate to antibiotic therapy, improved living conditions, and decreased virulence of the infecting organism (1). Recently, however, group A streptococcal infections have re-emerged as a public health problem. In 1985 and 1986, clusters of patients with rheumatic fever were reported from several areas (2-6), and since 1987, a severe syndrome associated with group A streptococcal infection (streptococcal toxic-shock-like syndrome) has been recognized (7,8).
The findings in Denver are consistent with a trend toward increasing rates of GABHS bacteremia. While a direct comparison of the GABHS bacteremia incidence rate in Denver for 1989 and for previous years is not possible because of incomplete laboratory records, the 1989 rate is more than double the most recent population-based estimate of three cases per 100,000 persons per year from Charleston County, South Carolina (1985-1987) (CDC, unpublished data). In addition, during 1989, CDC received an increased number of reports of GABHS bacteremia from other areas in the United States and serotyped strains from several Scandinavian countries that have increased rates of GABHS bacteremia. These reports suggest widespread changes in the epidemiology of group A streptococcal disease.
The descriptive epidemiology of GABHS bacteremia in the Denver patients is similar to that in previous reports (9,10). Even though all age groups may be affected, disease occurs primarily in the elderly, including nursing home residents. Underlying medical conditions in affected persons may include chronic debilitating disease, immunosuppressive illness or medication, and intravenous-drug use. In addition, surgery, traumatic injury, or other disruption of the cutaneous barrier may predispose persons to invasive infection. Meningitis, endocarditis, osteomyelitis, septic arthritis, and genitourinary infections can occur in association with bacteremia. Despite appropriate therapy, illness can progress to shock, disseminated intravascular coagulation, and death; reported mortality rates range from 5% to 45% (9).
Streptococcal toxic-shock-like syndrome also has been reported recently from the Rocky Mountain area (7). This condition has been associated with pyrogenic exotoxin-producing group A streptococcal strains. Clinical features include fever, shock, localized erythema, renal failure, severe tissue injury (myositis and fasciitis), and adult respiratory distress syndrome; bacteremia may occur and illness is often fatal (7,8). The clinical manifestations in some of the Denver patients were compatible with this syndrome.
Factors contributing to the apparent recent increase in GABHS bacteremia are unclear. No single serotype, to suggest a common source, was found in the isolates from Denver. Serologic typing of group A streptococcal strains based on antigenic differences in the M-protein suggests that an increase in the proportion of virulent organisms may play a role. M-types 1 and 3, comprising 75% of the Denver isolates, may be more invasive and more likely to cause clusters of infection than most other streptococcal M-types (11). Analysis of serotyping data from isolates submitted to CDC since 1972 shows an increase in the proportion of these two M-types in the 1980s (11).
Efforts to prevent and control invasive group A streptococcal disease should be directed at surveillance to establish the incidence of this problem in different geographic areas; further epidemiologic studies of toxic-shock-like syndrome; and improved understanding of the roles of immune responses, exotoxin, and other virulence factors. Physicians should continue to diagnose and treat mild streptococcal infections to prevent their progression to severe invasive disease.
On July 14, 1989, CDC notified state and territorial health officials of a possible increase in severe group A streptococcal infections and requested that clusters of invasive group A streptococcal infection or illness in previously healthy persons be reported through state health departments to the Respiratory Diseases Branch, Division of Bacterial Diseases, Center for Infectious Diseases, CDC; telephone (404) 639-3021.
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