The changing epidemiology of group a Streptococcus infections

Streptococcal emm types in Hawaii: a region with high incidence of acute rheumatic fever

BACKGROUND

The clinical epidemiology of group A streptococcal (GAS) infections in Hawaii seems different from that in the continental United States with frequent skin infections and endemically high rates of acute rheumatic fever (ARF).

METHODS

GAS emm types in Hawaii were determined to identify any possible association between the emm types and specific clinical manifestations. A convenience sample of 1482 Hawaii GAS isolates collected between February 2000 and December 2005 was used. All isolates were characterized by emm sequence typing. The distribution of emm types in Hawaii was compared with the published continental US data for pharyngeal and invasive GAS strains, the CDC database from similar time periods, as well as with emm types present in a candidate GAS vaccine.

RESULTS

Ninety-three distinct emm types were recognized among the 1482 GAS isolates. The most frequently identified emm types in order of decreasing frequency were 12, 1, 28, 4, 22, 77, 81, 58, 65/69, 49, 74, 85, 92, 75, 101 and 2. Of this study sample, 27 of the 50 invasive GAS isolates belonged to uncommon continental US emm types (54% in Hawaii cultures vs. 10% reported from the continental US). Of the 1179 pharyngeal isolates, 509 belonged uncommon continental US emm types (43% in Hawaii cultures vs. 27% reported from the continental US).

CONCLUSIONS

The prevalent emm types in Hawaii differ from those in the continental US. The prevalence of these unusual emm types might limit the effectiveness of any proposed multivalent type-specific GAS vaccine in Hawaii.

Invasive group a streptococcal disease in nursing homes, Minnesota, 1995-2006

Nursing home residents are at high risk for invasive GAS disease; clusters are common.

Nursing home residents are at high risk for invasive group A streptococcal (GAS) disease, and clusters of cases in nursing homes are common.To characterize the epidemiologic features of invasive GAS disease in nursing homes, we conducted active, statewide, population- and laboratory-based surveillance in Minnesota from April 1995 through 2006. Of 1,858 invasive GAS disease cases, 134 (7%) occurred in nursing home residents; 34 of these cases were identified as part of 13 clusters. Recognizing cases of GAS disease in nursing homes posed challenges. Measures to ensure identification of case-patients as residents of specific nursing homes need to be included in standard guidelines for the prevention and control of invasive GAS disease in this setting.

Invasive group a streptococcal disease in nursing homes, Minnesota, 1995-2006

Nursing home residents are at high risk for invasive group A streptococcal (GAS) disease, and clusters of cases in nursing homes are common.To characterize the epidemiologic features of invasive GAS disease in nursing homes, we conducted active, statewide, population- and laboratory-based surveillance in Minnesota from April 1995 through 2006. Of 1,858 invasive GAS disease cases, 134 (7%) occurred in nursing home residents; 34 of these cases were identified as part of 13 clusters. Recognizing cases of GAS disease in nursing homes posed challenges. Measures to ensure identification of case-patients as residents of specific nursing homes need to be included in standard guidelines for the prevention and control of invasive GAS disease in this setting.

The epidemiology of invasive group A streptococcal infection and potential vaccine implications: United States, 2000-2004

BACKGROUND

Invasive group A Streptococcus (GAS) infection causes significant morbidity and mortality in the United States. We report the current epidemiologic characteristics of invasive GAS infections and estimate the potential impact of a multivalent GAS vaccine.

METHODS

From January 2000 through December 2004, we collected data from Centers for Disease Control and Prevention's Active Bacterial Core surveillance (ABCs), a population-based system operating at 10 US sites (2004 population, 29.7 million). We defined a case of invasive GAS disease as isolation of GAS from a normally sterile site or from a wound specimen obtained from a patient with necrotizing fasciitis or streptococcal toxic shock syndrome in a surveillance area resident. All available isolates were emm typed. We used US census data to calculate rates and to make age- and race-adjusted national projections.

RESULTS

We identified 5400 cases of invasive GAS infection (3.5 cases per 100,000 persons), with 735 deaths (case-fatality rate, 13.7%). Case-fatality rates for streptococcal toxic shock syndrome and necrotizing fasciitis were 36% and 24%, respectively. Incidences were highest among elderly persons (9.4 cases per 100,000 persons), infants (5.3 cases per 100,000 persons), and black persons (4.7 cases per 100,000 persons) and were stable over time. We estimate that 8950-11,500 cases of invasive GAS infection occur in the United States annually, resulting in 1050-1850 deaths. The emm types in a proposed 26-valent vaccine accounted for 79% of all cases and deaths. Independent factors associated with death include increasing age; having streptococcal toxic shock syndrome, meningitis, necrotizing fasciitis, pneumonia, or bacteremia; and having emm types 1, 3, or 12.

CONCLUSIONS

GAS remains an important cause of severe disease in the United States. The introduction of a vaccine could significantly reduce morbidity and mortality due to these infections.

Emerging gram-positive bacterial infections

Over the last several decades, a number of previously known or newly described species of gram-positive bacteria have emerged as important human pathogens, particularly in industrialized countries. These microbes have demonstrated an impressive ability to produce an array of striking infectious diseases never before seen or only infrequently encountered in the past. Despite aggressive therapeutic intervention, many of these conditions portend significant morbidity and mortality. Diseases caused by members of the Staphylococcus and Streptococcus genera have figured prominently in this regard, with Staphylococcus aureus, S. epidermidis, Streptococcus pyogenes, and other beta-hemolytic streptococci being regarded as the most important species. This review focuses on the clinical and microbiologic aspects of key emerging infections caused by this group of microorganisms.

Epidemiology of invasive group a streptococcus disease in the United States, 1995-1999

Severe invasive group A streptococcal (GAS) disease is believed to have reemerged during the past 10-20 years. We conducted active, laboratory, population-based surveillance in 5 US states (total population, 13,214,992). From 1 July 1995 through 31 December 1999, we identified 2002 episodes of invasive GAS (3.5 cases per 100,000 persons). Rates varied by age (higher among those <2 or >/=65 years old), surveillance area, and race (higher among black individuals) but did not increase during the study period. The 5 most common emm types (1, 28, 12, 3, and 11) accounted for 49.2% of isolates; newly characterized emm types accounted for 8.9% of isolates. Older age; presence of streptococcal toxic shock syndrome, meningitis, or pneumonia; and infection with emm1 or emm3 were all independent predictors of death. We estimate that 9600-9700 cases of invasive GAS disease occur in the United States each year, resulting in 1100-1300 deaths.

Invasive group A streptococcal infection and nonsteroidal antiinflammatory drug use among children with primary varicella

OBJECTIONS

To test the hypothesis that nonsteroidal antiinflammatory drug use increases the risk of necrotizing soft tissue infections and, secondarily, all invasive group A streptococcal (GAS) infections in children with primary varicella infection.

METHODS

We conducted a prospective, multicenter case-control study among children <19 years old. Cases were children hospitalized with primary varicella complicated by invasive GAS infection or necrotizing soft tissue infection identified by a network of 45 pediatric infectious disease specialists located throughout the United States. Controls were children with uncomplicated primary varicella residing in the same communities as the cases. Data on medical history, clinical features of the varicella infection, signs and symptoms of infectious complications, and medication use were collected by structured telephone interviews. Univariate and multivariate matched odds ratios were calculated using conditional logistic regression.

RESULTS

Between June 1996 and September 1998, 52 cases of invasive GAS infection, including 21 with necrotizing soft tissue infection, and 172 controls with uncomplicated primary varicella were enrolled. Risk of invasive GAS infection was increased among children who were nonwhite (multivariate odds ratio [OR] 3.8, 95% confidence interval [CI]: 1.4-11), living in low-income households (OR 5.1, 95% CI: 1.7-15), exposed to varicella at home (OR 6.4, 95% CI: 2.6-16), or had a persistent high fever (OR 9.6, 95% CI: 2.8-33). Antipyretic regimen was associated with several measures of varicella illness severity among the controls. The risk of necrotizing soft tissue infection was not associated with the use of ibuprofen before the development of signs or symptoms of this complication (OR 1.3, 95% CI: 0.33-5.3). Risk of any invasive GAS infection was increased among children who had received ibuprofen (OR 3.9, 95% CI: 1.3-12), but not acetaminophen (OR 1.2, 95% CI: 0.50-3.0). However, there was no evidence of increasing risk with increasing duration of ibuprofen use. Subgroup analyses revealed that the risk of invasive GAS infection was increased only among children who had received both acetaminophen and ibuprofen.

CONCLUSIONS

These data do not support the hypothesis that nonsteroidal antiinflammatory drugs, or ibuprofen in particular, increase the risk of necrotizing GAS infections. A statistically significant association was observed between nonnecrotizing invasive GAS infection and ibuprofen use; however, because of potential confounding, the meaning of this unexpected result is unclear. Nonetheless, these data suggest that parents use ibuprofen or ibuprofen together with acetaminophen to treat high fever and severe illness, which seems to identify children at high risk for invasive GAS infection.

Survival following group A streptococcal septicaemia in a centenarian

We report a case of a centenarian who survived group A streptococcal septicaemia without complications. We would be interested to hear if this patient is the oldest survivor of group A streptococcal septicaemia in the U.K.